GSM BSNL Training Part2

mUu;u ikB~;Øe /Up gradation course

Reading Material

Handout No-ALTMCUP114 02 Rev 2 28.02.2008

Technology Module

i

About this Handout

This handout provides reading material on the technical topics included in the Syllabus of E3 to E4 Time scale promotion linked training of Officers belonging to Telecom wing of BSNL. The examination at the end of this one-week module will include discussions that take place in the class and general understanding of BSNL executives about the company’s telecom infrastructure. Mode of Examination The examinations will be conducted with break-up of 30% subjective & 70% objective pattern questions in each of the modules. Duration of Examination Examination duration will be 90 minutes Qualifying marks For the successful completion of the training, the executive undergoing the training ought to score a minimum of 50% of the total marks in each of the modules. Failure & Re-appearance The Executives who don’t qualify the examination would be given another chance to undertake/clear the examination in continuation of their training. This supplementary examination would be arranged within 3 days of the declaration of the results at the same venue. For still failing executives, a second / subsequent supplementary examination would be held on the date & place as finalized by ALTTC. However no TA/DA would be admissible to the executives appearing for the same. No repeat of training would be provided for the unsuccessful executives, unless specifically agreed by the CGM ALTTC in consultation with corresponding circle CGM. Reference:

1. Order No. 32-27/04/Trg dated 19th July 2007 of BSNL Corporate office

2. Order No. 32-27/04/Trg dated 12th April 2007 of BSNL Corporate office

Suggestions/Modifications/Improvements may be conveyed to:

DGM (MC), ALTTC, Ghaziabad

ii

CONTENTS

TOPIC Chapter Page

SECTION-I Switching

Digital Switching systems: Concepts 1 1-4

Signaling: CCS7 2 1-6

NGN & BSNL Plans 3 1-7

Intelligent Network 4 1-12

Maintenance issues of battery and power plant 5 1-5

Section-II Transmission

Overview of DWDM 1 1-8

DWDM System Engineering & planning 2 1-6

DWDM Measurements & testing Instruments 3 1-11

Overview of Next generation SDH 4 1-6

SECTION-III Mobile

Overview of Mobile Communication & cellular concepts 1 1-6

GSM Architecture 2 1-5

GPRS/EDGE 3 1-6

GSM Services 4 1-9

Overview of CDMA Technology 5 1-14

SECTION-IV Data Communications

Broadband Wire line & Wireless Access Technologies 1 1-12

TCP/IP/Ethernet, IP Addressing 2 1-10

NIB & Multiplay 3 1-7

MPLS-VPN 4 1-7

Metro Ethernet 5 1-7

SECTION-V Information Technology

BSNL Application Packages 1 1-12

Overview of NOS & RDMS Package 2 1-4

IT Security Policy 3 1-3

iii

Amendment Record

TOPIC Version Date

SECTION-I Switching

Digital Switching systems: Concepts 2 28.02.2008

Signaling: CCS7 2 28.02.2008

NGN & BSNL Plans 2 28.02.2008

Intelligent Network 2 28.02.2008

Maintenance issues of battery and power plant 1 14.12.2007

Section-II Transmission

Overview of DWDM 1 14.12.2007

DWDM System Engineering & planning 1 14.12.2007

DWDM Measurements & testing Instruments 1 14.12.2007

Overview of Next generation SDH 1 14.12.2007

SECTION-III Mobile

Overview of Mobile Communication & cellular concepts 2 28.02.2008

GSM Architecture 2 28.02.2008

GPRS/EDGE 2 28.02.2008

GSM Services 2 28.02.2008

Overview of CDMA Technology 1 14.12.2007

SECTION-IV Data Communications

Broadband Wire line & Wireless Access Technologies 2 28.02.2008

TCP/IP/Ethernet, IP Addressing 2 28.02.2008

NIB & Multiplay 2 28.02.2008

MPLS-VPN 2 28.02.2008

Metro Ethernet 2 28.02.2008

SECTION-V Information Technology

BSNL Application Packages 1 14.12.2007

Overview of NOS & RDMS Package 1 14.12.2007

IT Security Policy 2 28.02.2008

Section-I

Chapter-1

Digital Switching Systems

E3E4 Switching Concepts, Ver2 28.02.2008 1 of 4

1.0 DIGITAL SWITCHING CONCEPTS

Telephony was invented in 1876 and automatic telephone exchanges were developed in 1895. All these exchanges were analog. Now we have only digital exchanges in the network, which work on time switching or time and space switching. The digital exchanges are compatible to provide value added services and Intelligent services Communication can be defined as the transfer of information from one point to another point as per desire of the user under the control of some system. The key aspects of a communication network are :

1) Switching 2) Transmission 3) Call control or signaling 4) End terminals or network elements

2.0 SWITCHING Switching is basically establishing a temporary path or connection between two points or it can also be defined as writing at one point of time and reading at another point of time.

There are two modes of switching employed in our network. 2.1 CIRCUIT SWITCHING

In normal telephone service , basically, a circuit between the calling party and called party is set up and this circuit is kept reserved till the call is completed. Here two speech time sots are involved one of calling subscriber other of called subscriber. It is called circuit switching Circuit switching is based on the principle of sampling theorem.

2.1.1 SAMPLING THEOREM Sampling Theorem States “If a band limited signal is sampled at regular intervals of time and at a rate equal to or more than twice the highest signal frequency in the band, then the sample contains all the information of the original signal. Mathematically , if fh is the highest frequency then sampling frequency Fs needs to be greater than or equal to 2 fh i .e. Fs >=2 fh Let us say our voice signals are band limited to 4 KHZ and let sampling frequency be 8KHZ. .


. . Time period of sampling Ts = 1 secs. 8000 . or Ts = 125 micro second If we have just one channel then this can be sampled every 125 microseconds and the resultant samples will represent the original signal. But if we are to sample N channels one by one at the rate specified by the sampling theorem, then the time available for sampling each channels would be equal to Ts/N microseconds The time available per channel would be Ts=125µs N=32 for 32 chl PCM 125/32=3.9 microseconds per chl Thus in a 30 channel PCM system, time slot is 3.9 microsecond and time period of sampling i.e. interval between 2 consecutive samples of a channels is 125 microsecond. This duration i.e. 125 microsecond is called time Frame. A signal band is limited to max freq of say fm if sampled at the rate of 2fm then this signal can be reconstructed at the receiving end. This theorem was given by Nyquist.

2.2 PACKET SWITCHING The information (speech, data etc) is divided into packets each packet containing piece of information also bears source and destination address. These packets are sent independently through the network with the destination address embedded in them. Each packet may follow different path depending upon the network.

3.0 SWITCHING CONCEPT

To connect any two subscribers, it is necessary to interconnect the time-slots of

the two speech samples which may be on same or different PCM hightways. The

digitalised speech samples are switched in two modes. Viz. Time Switching and

space Switching . This time Division Multiplex Digital Switching System is

popularly known as Digital Switching System

3.1 Digital Time Switch

Principle

A Digital Time Switch consists of two memories, viz., a speech or buffer

memory to store the samples till destination time-slots arrive, and a control

or connection or adddress memory to control the writing and reading of

the samples in the buffer memory and directing them on to the appropriate

time-slots.


Speech memory has as many storage locations as the number of time-slots

in input PCM,e.g.,32 location for 32 channel PCM system.

The writing / reading operations in the speech memory are controlled by

the control Memory It has same number of memory locations as for

speech memory, i.e.,32 locations for 32 channel PCM system. Each

location contains the address of one of the speech memory locations where

the channel sample is either written or read during a time-slot. These

address are written in the control memory of the CC of the exchange

depending upon the connection objective.

A Time –Slot Counter which usually is a synchronous binary counter. is

used to count the time – slots from 0 to 31 as they occur. At the end of

each frame, it gets reset and the counting starts again. It is used to control

the timing for writing/reading of the samples in the speech memory.

Buffer/speech memory

Incoming PCM 01 Outgoing PCM

02

04

TS4 TS6

31

Read address

00

01

06

31

Control

/Connection/Address

Memory

Fig. output Associated Control Switch

3.2 SPACE SWITCH:

A space switch is used to simple change the PCM of a incoming time slot

keeping the time slot number same in the outgoing PCM.

The memory location requirement rapidly go up as a Time Switch is expanded

making it uneconomical. Hence, it becomes necessary to employs both types of

switches, viz.., space switch and time switch, and therefore is known as two

dimensional network. These network can have various combinations of the two

types of switches and are denoted as TS, STS TSST, etc.

4 ( four)

Time slot

counter


4.0 Telecom network structure The telecom network consists of –

Local exchanges (LE) Which has only subscribers connected to it. TAX Exchanges (TAX) Trunk automatic exchanges contains only outgoing and incoming circuits and no subscriber is connected to it. It is used only for routing calls. Tandem exchanges Out going and incoming tandem exchanges are basically exchanges between TAX and local exchanges for better management of traffic. These exchanges do not connect subscribers. Network elements (like telephone, fax, modem etc.)

The telephone network is also referred as PUBLIC SWITCHED TELEPHONE NETWORK (PSTN) .The offered voice service is referred as PLAIN OLD TELEPHONE SERVICE (POTS) The PSTN network is organized in a hierarchical manner with Lev-1/Lev-2 TAX

exchanges and then tandem and Local exchanges. Trunk Automatic Exchange

Lev-I TAX -------In 21 places

Lev-II TAX-------In 301 Places

Types of call

• Local call: Call originated and terminated in the same exchange is called local

call

• Outgoing call: Call originated from local exchange and terminated in other

exchange after picking up outgoing circuit.

• Incoming call: Call received from other exchange and terminated in local

exchange.

• Transit call: Call received from other exchange and terminated in other exchange.

When a new call is set up, it needs to be routed from calling party to the called party

through the switch network. The routing is based on the called party number. Normally in

PSTN the switching is ‘static’ type. In case of link failure alternate paths are available

and routing is done through the alternate paths.

Section-I

Chapter-2

Signaling: CCS7

E3E4 Signaling: CCS7, Ver2 28.02.2008 1 of 6

Signaling in Telecom Networks

Common Channel Signaling System No. 7

A signaling system is called a common channel signaling system when the signaling information related to a group of circuits is transported over a separate common signaling link.

1.0 Basic Concepts CCS No. 7 is a CCS (Common Channel Signaling) system which may be used in an associated and non-associated mode of operation. CCS7 being a common channel signaling system, has following features –

• Based on separation of speech circuit from the signaling link.

• Speech ckt has no signaling function except when a continuity check is done.

• Results in faster call setup

• Efficient utilisation of speech ckts. The overall objective of CCS No. 7 is to provide an internationally standardized general purpose CCS system:

• optimized for operation in digital telecommunications networks in conjunction with stored program controlled exchanges.

• that can meet present and future requirements of information transfer for inter-processor transactions within telecommunications networks for call control, remote control and management and maintenance signaling

• that provides a reliable means of transfer of information in correct sequence and without loss or duplication.

The signaling system is optimized for operation over 64-Kbit/s digital channels. It is also suitable for operation over analog channels and at lower speeds. The system is suitable for use on point-to-point terrestrial and satellite links.

1.1: Functional Blocks in CCS No. 7 The CCS No. 7 consists of the following functional blocks:

• MTP (Message Transfer Part)

• TUP (Telephone User Part)

• ISUP (ISDN User Part)

• SCCP (Signaling Connection Control Part)

• TC (Transaction Capabilities)


Fig.3 Architecture of CCS no7

Level Structure of CCS No. 7 The CCS No. 7 protocol has a layered structure consisting of four levels (fig 4):

• Level 1 defines the physical, electrical and functional characteristics of the signal link.

• Level 2 defines functions relevant to individual signaling links, including error control and link monitoring. This level is responsible for reliable transfer of signaling information between two directly connected signaling points.

• Level 3 defines network functions such as message routing and network management.

• Level 4 defines application and user functions. User parts are defined to control the establishment and release of traffic circuits.

The first three levels together form the Message Transfer Part (MTP). The functions of each of the CCS No. 7 layers are transparent to one another because of well-defined interfaces between them. A mechanism has been provided to deliver CCS messages of up to 272 octets between the MTP and the user part, and within the user part.


Fig .4

Signalling Associations A CCS7 network can have following types of associations between speech and signaling path –

• Associated -Signaling path same as speech path

• Non-associated - Signaling path different from speech path and the signaling path to be used not specifically determined.

• Quasi-associated - Non-associated with a predetermined signaling path.

Fig. 5 – Associated and Quasi-associated mode of signalling 1.2: CCS No. 7 Network Elements The signaling network consists of several network elements: · SEP (Signaling End Point) · STP (Signaling Transfer Point) · STEP (Signaling Transfer and End Point)

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

CCS link

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

CCS link


- - - - - Voice ckt Signalling link

Fig.6 Network Elements An SEP provides high speed, Common Channel Signaling connections for the speech circuits which terminate at its exchange. Signaling messages arriving at an SEP are used to set up the necessary speech circuits to complete a telephone call to the end user. The STP transfers signaling messages that arrive on one signaling link to a second signaling link where the message will then be routed toward the destination. An STP does not contain voice circuits, but it does provide the important function of transferring messages (either to another STP or to an SEP) towards their ultimate destination. The STEP performs both the SEP and STP functions. The STEP can transfer signaling messages that are destined for another exchange, and it can analyze signaling messages used to set up speech circuits in its exchange.

1.3 Signal Unit Composition ITU-T Signaling System No. 7 signals are sent in packets known as signal units. The signal units vary in length according to the type of information transferred. There are three types of signal units:

• MSU (Message Signal Unit): This is used for transferring signaling information supplied by the MTP itself or by the user part or SCCP.

• LSSU (Link Status Signal Unit: This is used for transferring signaling information used to indicate and monitor the status of the signaling link.

• FISU (Fill-In Signal Unit): This is used when there is no signaling traffic to maintain link alignment.


Point Codes Every SP (Signaling Point) and STP (Signaling Transfer Point) when integrated in a network will be allocated its own unique point code. This is used by the MTP routing function to direct outgoing messages towards their destination in the network as indicated by the inclusion of the appropriate point code in the routing label. This point code is known as the DPC (Destination Point Code). The routing label also contains the point code of the SP originating the message known as the OPC (Originating Point Code). The combination of the OPC and the DPC will determine the signaling relation. If two or more signaling links are required then the message handling function performs load sharing over the links. In this case the SLS (Signaling Link Selection) field is used to identify the chosen link.

1.4 User Part The CCS No. 7 functional Level 4, known as the MTP User functions, defines the functions of the signaling system that are particular to users. The ITU-T has defined several user functions of CCS No. 7, important are:

TUP - Telephone User Part ISUP - ISDN User Part SCCP - Signaling Connection Control Part TCAP - Transaction Capabilities Application Part

Telephone User Part The TUP defines the telephone signaling functions necessary for CCS No. 7 to control national and international telephone calls.

ISDN User Part The ISUP defines the signaling functions needed for basic and supplementary services for ISDN voice and non voice applications.

Signaling Connection Control Part The SCCP is used by call control for non-circuit related message transfer. Intelligent network features requiring database access, such as credit card verification, virtual private network services, and 800 services use connectionless SCCP in conjunction with TCAP to query these databases. ISDN supplementary services use TCAP and connectionless SCCP for sending information end-to-end. OMAP (Operations, Maintenance, and Administration Part) uses TCAP and the SCCP connectionless service in MTP and SCCP routing verification tests, and in circuit validation tests. Connection-oriented SCCP can be used for the ISUP user-to-user service 3 for data transfer, and is used for reliable data transfer on the interface between a base station and MSC (Message Switch Controller) in the GSM network.


Transaction Capabilities Application Part (TCAP)

The TCAP provides services for interactive applications distributed over exchanges and specialized centers in an CCS No. 7 telecommunication network. The TCAP provides the means to establish non-circuit related communication between two nodes in the signaling network. Some examples of interactive applications that use the services of TCAP are as follows:

• MAP (Mobile Application Part) used by GSM (Global Systems of Mobile communications)

• INAP (Intelligent Network Application Part)

• OMAP (Operations and Maintenance Application Part)

2.0 CCS7 Normal Call Processing Messages

• IAM (Initial Address Message): The IAM contains the dialed digits, voice/data trunk identity, and other related info. IAM/SAM contains all necessary information to set the path from one switch to the other.

• Check tone (optional): For speech path continuity check After completion the COT (Continuity Signal) message is sent. If the check tone fails, the CCF(Continuity Check Failure) message is sent .

• ACM (Address Complete Message)

• Audible ringing tone

• ANC (Answer, Charge): On receipt of the answer signal, charging is started.

• CLF (Clear Forward): If called subscriber hangs up first, the CLB (Clear-back) signal is sent in the other direction, followed by the CLF.

• RLG (Release Guard): When the incoming equipment is released, a release-guard signal is sent back.

Advantages of CCS7 signaling:

1. Faster call setup. 2. No interference between signalling tones by network and frequency of human

speech pattern. 3. Greater trunking efficiency due to the quicker set up and clear down, thereby

reducing traffic on the network. 4. No security issues related to the use of in-band signalling with CAS. 5. CCS allows the transfer of additional information along with the signalling traffic

providing features such as caller ID. 6. New services like IN services are possible because of CCS7 signaling. 7. Efficient utilisation of speech ckts.

Section-I

Chapter-3

NGN & BSNL Plans

E3E4 NGN & BSNL Plans Ver2 28.02.2008 1 of 7

NGN: CONCEPT AND ARCHITECTURE

The current generation network of BSNL, popularly known as PSTN is mainly

circuit switching based network and it is organized into an hierarchical architecture viz.

Level –I TAX exchanges, then Level-II exchanges and then tandem/local exchanges. The

PSTN network is mainly optimized for voice calls and not much suited for data services.

We have a separate network for data services.

Today the world over trend is for a single converged network used for all type of

services viz. voice, data, video which is called Next Generation Network and is a packet

switching based network. To change over from current generation network to next

generation network we have to move in a step-by-step manner to safeguard our existing

network infrastructure and investment and therefore we have to follow an evolutionary

path.

Why NGN?

The NGN concept takes into consideration new realities in the telecommunication

industry characterised by factors such as: the need to converge and optimise the operating

networks and the extraordinary expansion of digital traffic (i.e., increasing demand for

new multimedia services, increasing demand for mobility, etc.).

The other reasons why we should evolve our existing network to NGN are that the

existing circuit switched networks have following problems:

• Slow to develop new features and capabilities.

• Expensive upgrades and operating expenses.

• Proprietary vendor troubles

• Large power and cooling requirements.

• Limited migration strategy to New tech.

• Model obsolescence.

What is NGN? ITU-T’s Definition of NGN A Next Generation Network (NGN) is a packet-based network able to provide

Telecommunication Services to users and able to make use of multiple broadband, QoS-

enabled transport technologies and in which service-related functions are independent of

the underlying transport-related technologies. It enables unfettered access for users to

networks and to competing service providers and services of their choice. It supports

generalised mobility which will allow consistent and ubiquitous provision of services to

users. < ITU-T Recommendation Y.2001 (12/2004) - General overview of NGN>.


As per ETSI NGN is a concept for defining and deploying networks, which due to

their formal separation into different layers and planes and use of open interfaces,

offers service providers and operators a platform, which can evolve in a step-by-step

manner to create, deploy and manage innovative services.

The following diagram depicts the concept of NGN.

Current Gen networks NGN

Fig1

In NGN basically the call control (i.e. signaling) and the switching is separated

out in different layers and between these layers open interfaces are used. The call control

functionality is realised by the component which is called call server or softswitch or

media gateway controller and the interfaces to the existing PSTN switches is done with

the help of media gateways for voice transport and by signaling gateways for signaling

transport. For switching and transport of the packets existing IP/MPLS backbone is used.

With NGN architecture the new and innovative services can be given very fast and cost

effectively. Also the capital expenditure and operational expenditure come down

drastically.

Interfaces

Switching

Call

Control Call

Server

IP/MPLS

Gateways

SDH Transport

with Overlay

packets for data

Common IP

MPLS

Transport over

SDH/

DWDM/Fiber


The NGN is characterised by the following fundamental aspects:

• Packet-based transfer • Separation of control functions among bearer capabilities, call/session,

and application/service • Decoupling of service provision from transport, and provision of open

interfaces • Support for a wide range of services, applications and mechanisms based

on service building blocks (including real time/streaming/non-real time services and multi-media)

• Broadband capabilities with end-to-end QoS and transparency • Interworking with legacy networks via open interfaces • Generalised mobility • Unfettered access by users to different service providers

The NGN Architecture

The NGN Architecture consists of several basic components – The Soft Switch,

Application Servers, Media Servers, Network Gateways and Access Gateways with the

IP-MPLS Packet Router Network providing the transport layer. Central to the NGN

architecture is the Soft Switch, which is a call server that allows multiple application

services to run concurrently. The block schematic of NGN components and usage of key

protocols are shown in Figure 2.

The Soft Switch is shown at the centre. The SIP Signaling server

provides signaling interface to IP End points in a Broadband environment. The

Application and Media servers work in conjunction with the Soft Switch to deliver the

specific application and the media related functions (such as an IVRS module) to the

customer.

The NGN network is interconnected to the PSTN network through Media

Gateways, which are controlled by the Soft Switch. The capability to interconnect the

soft switches with other soft switches either in one’s own network or in any other Service

Provider’s network is done through Network Gateways.


Fig 2

Functions of Soft Switch (or Call Agent or Telephony Server or Media

Gateway Controller) 1. Based upon Open Architecture

2. Provide all existing services available in TDM network

3. Performs Media Gateway Control Function

4. Performs Call control, signalling and interworking, Traffic measurement and recording functions

5. Provides Addressing, Analysis, routing and charging facilities 6. Interacts with Application Server to supply services not hosted on

Softswitch 7. Should preferably be developed on Commercially Available Hardware and

Software Platforms.

Functions of Signalling Gateway 1. Provides interworking function between SS7 network and IP network

2. This involves providing various types of User Adaptations so that the SS7

signalling can be terminated in SGW and can be translated and messages

transported over IP Network

3. Performs Packetization of signalling and ensures its transport through IP network


Functions of Trunk Media Gateway Performs the functions of

1. Voice encoding & Compression

2. Packetization of voice channels

3. CNF (Comfort Noise Generation)

4. VAD (Voice Activity Detection)

5. Echo Cancellation

6. May provide the edge functionality and act as CE

The protocols used are: Between Softswitch and media gateway – H.248/Megaco, MGCP

Between two softswitches - SIP(T) or BICC

Between Softswitch and Signaling gateway - sigtran suite of protocols consisting of

M3UA, M2UA, M2PA, SUA, SCTP etc

Between softswitch and Application server- SIP, Parley ,Jain etc.

Between two media gateways for actual packet transfer- RTP/RTCP


IP TAX IN BSNL

“IP TAX is the first step towards the Evolution of Current Generation

Network to Next generation Network” in BSNL. In other words IP TAX is the

replacement of existing Level –I TAX exchanges to IP based network (Packet switching

network) and rest all the network still remaining circuit switched network. Presently IP

TAX will be installed in parallel to the Lev-I TAX and then it will replace circuit

switched TAX completely with IP TAX.

Generic reference diagram for IP TAX is as below:

Fig 1

Based on the above GR BSNL intends to install as per below given plan:

• Setting up Two Soft Switches at New Delhi and Chennai and

• Signalling Gateways at New Delhi, Chennai, Kolkotta and Bangalore

• Providing Trunk Media Gateways (TMGs) at 21 Level-1 locations

• Providing one Announcement Servers in each IP domain i.e. one at New Delhi

and one at Chennai.

• Billing interface to Centralized Billing Server at Chennai.

• NMS at Chennai with FCAPS

(Fault,Configuration,Accounting,Performance,Security) capabilities. No separate NTP server is being used in IP TAX, the existing NTP server of our

data network will be used for synchronization.


Following architecture is going to be installed:

Fig 2

BSNL’s NGN plans and vision

After the successful implementation of the 200KC pilot project of IP TAX the

BSNL is also in the process of procuring 6400 K lines of the IP TAX in the network in

year 2008-09. This IP TAX project is called class 4 NGN architecture. BSNL Corporate

office is also planning to go for class 5 NGN architecture in which Access Gateways/

Line Gateways will be installed. The ordinary subscribers will be connected to these

Access Gateways/ Line Gateways instead of the PSTN local exchanges. These Access

Gateways/ Line Gateways will be controlled by Softswitch. Simultaneously BSNL is

also envisaging to deploy IMS(IP Multimedia Subsystem) to introduce SIP based

services and also to have Fixed and Mobile convergence.

After successful implementation of class 5 NGN architecture BSNL corporate

office has a vision of replacing the PSTN local exchanges by softswitch NGN

architecture gradually. It is envisaged that by 2016 PSTN network will be completely

replaced by NGN and there will be about 1 billion lines of converged NGN network in

BSNL. To support this much IP subscriber traffic BSNL will have to augment the MPLS

core network in all SSAs in 2008-09 and in all DHQs in year 2009-10. IPv6 will be

introduced in the IP/MPLS core. To augment the transmission capacity BSNL plans to

have a mesh connectivity by STM- 256 network between 24 core routers of the IP/MPLS

network and Edge routers at circle level to be connected to core nodes through 10 Gbps

and 2.5 Gbps links.

Section-I

Chapter-4

Intelligent Network and Services

E3E4 IN services Ver2 28.02.2008 1 of 12

1.0 INTELLIGENT NETWORK

Over the last thirty years one of the major changes in the implementation of Public

Switched Telephone Networks (PSTN) has been the migration from analogue to digital

switches. Coupled with this change has been the growth of intelligence in the switching

nodes. From a customer’s and network provider’s point of view this has meant that new

features could be offered and used. Since the feature handling functionality was resident

in the switches, the way in which new features were introduced into the network was by

introducing changes in all the switches. This was time consuming and fraught with risk of

malfunction because of proprietary feature handling in the individual switches. To

overcome these constraints the Intelligent Network architecture was evolved both as a

network and service architecture.

In the IN architecture, the service logic and service control functions are taken out of the

individual switches and centralized in a special purpose computer. The interface between

the switches and the central computer is standardised. The switches utilize the services of

the specialized computer whenever a call involving a service feature is to be handled. The

call is switched according to the advice received by the requesting switch from the

computer. For normal call handling, the switches do not have to communicate with the

central computer.

1.1. Objectives of the Intelligent Network

The main objectives of the IN are the introduction and modification of new services in a

manner which leads to substantial reduction in lead times and hence development costs,

and to introduce more complex network functions. An objective of IN is also to allow the

inclusion of the additional capabilities and flexibility to facilitate the provisioning of

services independent of the underlying network's details. Service independence allows

the service providers to define their own services independent of the basic call handling

implementation of the network owner. The key needs that are driving the implementation

of IN are:

Rapid Service Deployment Most businesses today require faster response from their suppliers, including

telecommunication operators. By separating the service logic from the underlying switch

call processing software, IN enables operator to provide new services much more rapidly.

Reduced Deployment Risk

Prior to IN, the risk associated with the deployment of new services was substantial.

Major investments had to be made in developing the software for the services and then

deploying them in all of the switches. With the service creation environment available,

the IN services can be prototyped, tested and accessed by multiple switches

simultaneously. The validated services can then be rolled out to other networks as well.


Cost Reduction

Because the IN services were designed from the beginning to be reusable, many new

services can be implemented by building on or modifying an existing service. Reusability

reduces the overall cost of developing services. Also, IN is an architecture independent

concept, i.e. it allows a network operator to choose suitable development hardware

without having to redevelop a service in the event that the network configuration

changes.

Customization

Prior to IN, due to complexity of switch based feature handling software, the

considerable time frame required for service development prevented the provider from

easily going back to refine the service after the customer started to use it. With IN, the

process of modifying the service or customization of service for a specific customer is

much less expensive and time consuming. The customization of services is further

facilitated by the integration of advanced peripherals in the IN through standard

interfaces. Facilities such as voice response system, customized announcements and text

to speech converters lead to better call completion rate and user friendliness

of the services.

1.2. IN Architecture

Building upon the discussion in the previous section, one can envisage that an IN would

consist of the following nodes:

� Specialized computer system for - holding services logic, feature control, service

creation, customer data, and service management.

� Switching nodes for basic call handling

� Specialized resources node

The service logic is concentrated in a central node called the Service Control Point

(SCP).

The switch with basic call handling capability and modified call processing model for

querying the SCP is referred to as the Service Switching Point(SSP).

Intelligent Peripheral (IP) is also a central node and contains specialized resources

required for IN service call handling. It connects the requested resource towards a SSP

upon the advice of the SCP.

Service Management Point (SMP) is the management node, which manages services

logic, customers data and traffic and billing data. The concept of SMP was introduced in

order to prevent possible SCP malfunction due to on-the-fly service logic or customer

data modification. These are first validated at the SMP and then updated at the SCP

during lean traffic hours. The user interface to the SCP is thus via the SMP.


Physical Plane

Service Switching Point (SSP)

The SSP serves as an access point for IN services. All IN service calls must first

be routed through the PSTN to the "nearest" SSP. The SSP identifies the incoming call as

an IN service call by analysing the initial digits (comprising the "Service Key") dialled by

the calling subscriber and launches a Transaction Capabilities Application Part (TCAP)

query to the SCP after suspending further call processing. When a TCAP response is

obtained from the SCP containing advice for further call processing, SSP resumes call

processing. The interface between the SCP and the SSP is G.703 digital trunk. The MTP,

SCCP, TCAP and INAP protocols of the CCS7 protocol stack are defined at this interface

Service Control Point (SCP)

The SCP is a fault-tolerant online computer system. It communicates with the

SSP's and the IP for providing guidelines on handling IN service calls. The physical

interface to the SSP's is G.703 digital trunk. It communicates with the IP via the

requesting SSP for connecting specialized resources. SCP stores large amounts of data

concerning the network, service logic, and the IN customers. For this, secondary storage

and I/O devices are supported. As has been commented before, the service programs and

the data at the SCP are updated from the SMP.

Service Management Point (SMP)

The SMP, which is a computer system, is the front-end to the SCP and provides

the user interface. It is sometimes referred to as the Service Management System (SMS).

It updates the SCP with new data and programs(service logic) and collects statistics from

it. The SMP also enables the service subscriber to control his own service parameters via

a remote terminal connected through dial-up connection or X.25 PSPDN. This

modification is filtered or validated by the network operator before replicating it on the

SCP. The SMP may contain the service creation environment as well. In that case

the new services are created and validated first on the SMP before downloading to the

SCP. One SMP may be used to manage more than one SCP's.

Intelligent Peripheral (IP)

The IP provides enhanced services to all the SSP's in an IN under the control

of the SCP. It is centralized since it is more economical for several users to share the

specialized resources available in the IP which may be too expensive to replicate in all

the SSPs. The following are examples of resources that may be provided by an IP:

� Voice response system

� Announcements

� Voice mail boxes

� Speech recognition system

� Text-to-speech converters


The IN architecture is depicted in below given Figure:

Data

Base

CCS7 Network

IP SSP

USER USER USER USER

Communication Interface

Data

Base Communication Interface

Program Interface

Communication Interface

Legend

SMP: Service Management Point

SCP: Service Control Point

Service switching Point

IP: Intelligent peripheral

SMP

SCP


1.3. DESCRIPTION OF IN SERVICE FEATURES

An IN service comprises mandatory (providing core functionality) and optional features.

A brief description of the various features that constitute the IN services offered as part of

IN solution is given in the following paragraphs.

Call Forwarding on Busy/No Answer (CFC)

This service feature allows the called user to forward calls if the called user is busy or

doesn't answer within a specified number of rings.

Customer Profile Management (CPM)

This feature allows the user to perform online modification of the password

(authorization Code).

Mass Calling (MAS)

This service feature allows processing of large numbers of incoming calls in a given time

span, generated by call-in broadcasts, advertisements or games, etc.

Origin Dependent Routing (ODR)

This service feature allows the subscriber to have calls routed according to the calling

party's area of origination. Based on the area of origination the subscriber can also accept

or reject the call.

Origination Call Screening (OCS)

This service feature allows the subscriber to bar the calls originating from certain areas

identified by their area codes.

Off-net Access (OFA)

This service feature allows a VPN user to access his or her VPN from any non-VPN

station by using a personal identification number.

Off-net Calling (ONC)

This service feature allows the VPN user to call any external public number from a VPN

location. Authorization is required for accessing this feature.

Premium Charging (PRMC)

This service feature allows for the pay back of the part of the cost of a call to the called

party, when he is considered a value added service provider. The call is charged at a

premium over normal call charge.

Private Numbering Plan (PNP)

This service feature allows the subscriber to maintain a numbering plan within his private

network, which is separate from the public numbering plan.


Reverse Charging (REVC)

This service feature allows the service subscriber to receive calls at his own expense and

be charged for the entire cost of the call.

Time Dependent Routing (TDR)

This service feature enables the subscriber to route calls based on time of day, day of

week and day of year. The precedence when more than one type of parameters are

specified for determining routing shall be

1. Day of year

2. Day of week

3. Time of day

Call Distribution (CD)

This service feature allows the subscriber to have the calls routed to more than one

directory number. Based on the values defined, only a percentage of calls are routed

to a directory number.


IN Services

• Virtual Card Calling Service (VCC)

• Account Card Calling service (ACC)

• Premium Rate Service (PRM)

• Universal Access Number service (UAN)

• Universal Personal Number (UPN)

• Tele Voting (T-VOT)

• Free Phone Service (FPH)

• Virtual Private Network (VPN)

• Fixed Line Pre-paid (FLPP)

Access Codes for IN Services :

Existing New Codes Service Access

1600 1800 Free Phone

1601 1801 VPN

1602 1802 VCC(ITC)

1603 1803 Tele voting (no charge)

1604 1804 ACC

1901 1860 UAN(Local)

1902 1861 Tele voting(Charge)

0900 1867 PRM

0901 1860 UAN(LD)

1868 UPN

1907 1807 UAN Mgmt

1808 UPN Mgmt

1809 VPN Mgmt


SCP Codes :

Kolkata 345

Bangalore 425

Lucknow 180

Ahmedabad 233

Hyderabad 424

SCP Locations :

Zone Location of IN

Platform

Circles Covered

East Kolkatta Bihar, Jharkhand, West

Bengal,Orissa,Assam, North East-I & II,

CTD and A&N Islands

South Bangalore TamilNadu, Kerala, Karnataka, Chennai

T.D.

North Lucknow UP (E), UP (W), Uttaranchal, Punjab,

Haryana, H.P., J&K and Rajasthan

West Ahmedabad Gujarat, Maharashtra, Madhya

Pradesh, Chattisgarh, AP

Central Hyderabad All India(Mass Calling)

Two platforms types:

� General Purpose IN (GPIN)

� Mass Calling IN (MCIN)

GPIN are in following Cities – Kolkata, Ahmedabad, Lucknow, Bangalore

MCIN is in the following City – Hyderabad


Virtual Card Calling Service (ITC) Also known as Indian Telephone Card. Meant for customers who want to make STD/ISD calls from any Bfone (may not be his own) and limit the usage. No metering will be there on the Calling Telephone Number. Metering will be there against the VCC account.

Access code : 1602-SCP Code- PIN – Destination No. (1802 by 30-04-2009)

Brand Name : ITC, i.e. India telephone card Most popular service Most revenue providing

Account Card Calling Service (ACC)

• To place calls from any PSTN phone to any destination no and have the cost of these calls charged to the account specified by the account card calling (ACC) number.

• Personal identification number(PIN) is required for o Balance enquiry o Making call o Change of PIN

• Subscriber can renew the account by depositing a fresh amount of money after expiry of existing deposit with in the validity period of the Account.

• Detailed record for all the ACC calls will be sent to the subscriber for his information.

Free Phone Service (FPH) or Toll Free No. Meant for customer oriented organizations who want that their customers should feel free to contact without worrying about call charges.

• Here the concept of reverse charging is applied with additional features.

• The service subscriber will have one logical number against more than one PSTN no. distributed all over the network. He can have his own routing plan using Time Dependent Routing, Origin Dependent Routing facilities.


Premium Rate Services

• Concept of charging on higher pulse rate for the Services rendered by the subscriber.

• The pulse rate will be decided by the subscriber. Caller is charged.

• The revenue will be shared by the Subscriber and BSNL

• He can have his own routing plan using TDR, ODR on local access basis.

• A typical PRM no. would look like 1867 XYZ ABCD Where Service Access Code : 1867 XYZ : 3 digit SCP code ABCD : Last 4 digits are PRM no

Universal Access Number Service

• Publish one number(unique IN number) and have the incoming call routed destination based on origin of call or time/day on which the call is made.

• The caller will be charged as per the normal charge of PSTN call.

• One logical number against more than one PSTN no. distributed all over the network.

Universal Personal Number Service

Outgoing facility also available in UPN service. It introduces the concept of Personal mobility rather than terminal mobility.

A subscriber to this service can receive or make calls using his Universal Personal Number from any BSNL phone.

The subscriber will be given some management codes and password. Using that he can convert/reconvert any BSNL phone into his Universal Personal Number.

All the calls made by subscriber using his UPN will be billed at his UPN by the IN platform.

The subscriber will be able to get all his calls incoming on the UPN number anywhere in India.

This is a service newly introduced through Alcatel IN Platform.


Virtual Private Network • Enables the subscriber to establish a private network using existing public

network resources.

• Virtual PABX and it can be nation wide.

• Individual members can have privileges-ON net.

• Calling possible from outside VPN-Off net

• Billing will be against the Group id

VPN Features

• Multi site Organization

• Short Group Numbers

• Abbreviated Dialing

• Date & Time Screening

• Exception List

• Call Duration Control

• Multiple Account Codes

• Dual Invoicing

• Call Forwarding

• Hunting List

• Substitution

Tele-Voting Service • To conduct telephonic public opinion polls and surveys. Thus provides

easiest way to conduct poll/survey.

• Opinion by dialing the advertised Tele-voting number. The calling user can be charged (Unit) or charge free.

• The service can be available based on origin or time basis.

Tele Vote Features

• Validity Period

• Counters

• Global Vote Counter

• Local Tele voting Counter per VOT number

• Winner Counter

• Black List • Origin Dependent Handling

• Day Type/Time Dependent Handling

• Pre Filtering at SSP


Fixed Line Pre-paid Service

Types of FLPP Services to be introduced in BSNL

1. PCO FLPP Account - offering only Prepaid Services (for Local +STD+ISD)

2. General FLPP Account - offering both Prepaid & Postpaid services

3. General FLPP Account offering only Prepaid services

FLPP PCO and FLPP General Pure pre paid - can be given to subscribers from AXE-

10, 5ESS, EWSD, E-10B, OCB-283 and not from CDOT.

Dialing Plan: Only Destination Number needs to be dialed.

Internal Routing Plan:

• As on date only OCB-283 exchanges can act as SSP and trigger the FLPP Calls to

the SCP.

• Rest of the new Technology exchange shall only prefix the FLPP Call with 1805-

345/ 233 and then the call shall be routed to nearest OCB –283 exchange which

will further trigger the FLPP Calls to the SCP.

• If the FLPP Call is originated from E-10B Exchange then the exchange shall

simply route to any of the new technology exchange. Further routing shall be as

explained above.

FLPP General ‘Pre paid over post paid’ - can be given to subscribers from AXE-10,

5ESS, EWSD, OCB-283 and not from E-10B, CDOT.

Dialing Plan:

a. Post paid by default : Only Destination Number needs to be dialed(this shall not be

FLPP Call).

b. To Make prepaid call: 1805 345/233 + destination number

Internal Routing Plan:

• As on date only OCB-283 exchanges can act as SSP and trigger the FLPP Calls to

the SCP.

• Rest of the new Technology exchange shall simply route the FLPP Calls to

nearest OCB -283 exchange which will further trigger the FLPP Calls to the SCP.

(Not available from CCB PCOs)

Note:

• FLPP ‘Prepaid over Post paid’ can not be provided from E-10B and C-DoT

exchanges because of its inability to send more than 16 digits on trunks.

• FLPP ‘Pure Prepaid’ can not be provided from C-DoT exchanges because of it

routes the local without treating it as IN Call and ISD calls can also be not made

because of its inability to send more than 16 digits on trunks.

Section-I

Chapter-5

Maintenance issues: Battery and Power plant

E3E4 Battery Power plant, Ver1 14.12.2007 1 of 5

GENERAL INTRODUCTION The power plant of any telecommunication system is usually referred as the ‘heart’ of the installation since the communication system can function only as long as power supply is available. Failure of power supply system in any installation renders the communication facilities offered by it to be instantly paralyzed. Requirement of Power Supply: Any power supply arrangement for a communication system must have two basic characteristics.

i. Reliability of the components of the power plant and continuity of the power supply.

ii. The power fed to the exchange equipment should be free from noise or hum

and to telegraph equipment from large ripple harmonics.

Maintenance – Free Secondary Cells

Maintenance free, valve-regulated lead-acid (VRLA) batteries ensure a reliable effective and user friendly source of power. It is spill proof and explosion resistant and there is no need to add water or to clean terminals. It has low self-discharge rate which eliminates the need for equalizing charges. The container is made of polypropylene. Each plate is individually wrapped by a highly absorbent, microporous glass separate developed specially for VRLA batteries. The chemically inert glass ensures life long service. The absorbed electrolyte ensures that there is no spillage even in the unlikely event of puncture of the cell. Gas evolution under float conditions is negligible. The water loss throughout life due to gassing is roughly 0.1% of the total electrolyte present in the cell. This will in no way affect performance and also eliminate the need for specially ventilated battery room and acid resisting flooring. As the batteries can be installed in stacks, there will be considerable space saving also. Various capabilities of Batteries are 120 AH, 400 AH, 600 AH, 1000AH, 1500 AH, 2000 AH, 2500 AH, 3000 AH, 4000 AH & 5000 AH. VRLA Technology – A brief review of Chemical Reaction The electrode in all lead acid batteries, including VRLA battery is basically identical. As the battery is discharged the lead dioxide positive active material and the spongy lead negative active material react with the sulphuric acid electrolyte to form lead sulphated and water. During charge, this process is reversed. The Coulombic efficiency of the charging process is less than 100% on reaching final stage of charging or under over charge conditions, the charging energy is consumed for electrolyte decomposition of


water and the positive plates generate oxygen gas and the negative plates generate hydrogen gas. Under typical charging conditions, oxygen at the positive plate occurs before hydrogen evolution at the negative. This feature is utilized in the design of VRLA batteries. In flooded cells, the oxygen gas evolved at the positive plate bubbles upwards through the electrolyte and is released through the vents. In MF-VRLA batteries the oxygen gas evolved, at the positive plate, instead of bubbling upwards in transported in the gas phase through the separator medium to the negative plate. The separator is a highly absorbent glass matrix type with very high porosity, designed to have pore volume in excess of the electrolyte volume (starved electrolyte design), due to which the oxygen gas finds an unimpeded path to the negative plate. the oxygen gas gets reduced by reaction with the spongy lead at the negative plate, turning a part of it into a partially discharged condition, there by effectively suppressing the hydrogen gas evolution at the negative plate. This is what is known as the oxygen recombination principle. The part of negative plate which was partially discharged is then reverted to the original spongy lead by subsequent charging. Thus a negative plate keeping equilibrium between the amount which turns into spongy lead by charging and the amount of spongy lead which turns into lead sulphated by absorbing the oxygen gas generated at the positive plate. The oxygen recombination principle can be shown by the following reaction: 1. Reaction at positive plate : H2O = 1/2 O2 + 2e ………(1) 2. Reaction at negative plate : Pb + 1/2 O2 = PbO ……….(2) PbO + H2SO4 = PbSO4 + H2O ……….(3) To reaction (1) PbSO4 + 2H + 2e = Pb + H2SO4 ………(4) To reaction (3) To reaction (2) 3. The total reaction at negative plate

1/2 O2 + 2H = H2O

Thus, the recombination technology makes the battery virtually Maintenance Free.


♦ Battery capacity :The energy that can be taken out of a battery before the cell voltage collapses is called the battery capacity. It is defined as Discharge current (A ) × Discharge Duration time (hours).

MONITORING OF VRLA BATTERIES

Following steps are required for monitoring of the VRLA Batteries: (a) Periodic physical inspection of each cell of the battery for cracks and leaking etc. (b) Discharge of battery for a short duration and recording the voltages of each cell

in the string. (c) Measurement of a mark deviation (>30%) in the impedance or conductance of

the cell as compared to the one recorded at the time of commissioning. (d) Measurement & recording of cell temp. periodically. (e) Float Voltage of cells & its comparison with the mid point voltage. (f) Float current in fully charged battery.

Periodic Physical Inspection: Check for any crack or leakage every month. If not every month, at least once in two months. Battery Partial Discharge Test: Put battery to a test discharge for 30 minutes by shutting power plant so that 20% of the battery is discharged. This can be decided by the table supplied by the manufacturer. Record the Voltage of each cell. Any cell showing more than 5% variation compared to voltage of other cell can be potential weak cell. Impedance Measurement:Take impedance measurement when the charger is on and the battery is on float. Any change in impedance/conductance of the cell more than 40% shows imminent failure of the battery/cell. A change of <30% shows a healthy battery/ cell. Temperature: Every 10 degree rise in battery temperature doubles the chemical reaction in the battery. The SMPS power plant takes care of the temperature by reducing the charging voltage but still it is important to measure individual cell temp. periodically and keep record for study and analysis. Float Voltage: Float voltage is another important parameter on which life and performance of the battery depends. The float voltage should be set to 2.25 V per cell and charge voltage to 2.3 V per cell taking the adjustment factor of 3 mV/cell per degree centigrade. Mid-point Voltage Measurement: Some battery monitors measure the midpoint voltage of each battery string. In this method the monitor will raise an alarm if there is a sufficient imbalance in the two half string voltages. Individual Cell Monitoring: In this technique, the voltage of each is measured and deviation in any of cell can be detected quickly.


Effect of Temperature on the battery: With rise in temperature the battery life decreases. For every 10 degree rise in temperature, the capacity of battery becomes half. There is a temperature compensation in SMPS Power Plants and it is 3 milli-volt per degree rise in temp. Life of battery:

• Batteries upto 200AH: 4 Years

• Batteries more than 200 AH: 6 years

SMPS(Switched Mode Power Supply) Power plant:

The salient features of SMPS power plant are:

1) The power system is intended primarily to provide uninterrupted DC power to telecom exchange and current for charging the batteries.

2) The system works from commercial AC mains which is rectified and regulated to -54 V DC and is fed to the equipment (exchange).

3) The modules switching frequency for SMPS is 107.5 kHz. Therefore size of the module is very compact.

4) The system has provision to connect three sets of VRLA batteries and facility to charge them simultaneously to ensure that uninterrupted DC power is always available to the exchange.

5) The power systems is suitable for VRLA batteries. Life of Power Plant:

• Static P/P : 15 years

• SMPS P/P: 15 years


Earthing

Purposes of Earthing Apart from protection from hazardous stray currents in electrical equipment in

Telecommunication circuits and equipments, earthing is provided for the following purposes:

(a) Reduction of Crosstalk and Noise :

One pole of the battery (+ve pole) is earthed in the telephone exchange so that cross talk between the various circuits due to the speech currents of one circuit finding path through the other via common battery feed points of the transmission bridge and poor NSN via earthed terminal of the battery is reduced.

(b) Protection of buildings and equipments from lighting strikes. (c) Used as return path for the conductors in some telegraph and voice circuits. (d) Protection of costly apparatus and persons against foreign voltages and

leakage currents from power wirings to the metallic frame of the equipment. (e) Earth is used to afford convenience &” reliability, in the operate path of the

circuits involved in the switching apparatus of telecom circuits. (f) Earthing power supply systems is used to effect reliability of power as it

helps to provide stability of voltage conditions preventing excess fluctuations and providing a measure of protection against lighting.

Earth Electrodes :

Three types of earth electrodes are commonly used for earthing systems. 1) Rod electrodes 2) Plate electrodes 3) Strip electrodes

Instruction for monitoring of Earth resistance were issued from Corporate office. As per the instruction:

• E/R is to be measured every six months.

• Earth resistance should be less than 0.5 Ώ for electronic

• One dry season must be included in these two occasions.

• For lightning prone area, it should be measured every month.

• Wherever, it is beyond limits, it should be immediately brought within limits.

• Procedure for laying earth resistance may be followed as prescribed in the latest issue of EI on Protection Earthing I-001.

• Reduction in card failure has been observed by improving the earth resistance.

Section-II

Chapter-1

Overview of DWDM

E3E4 DWDM Overview Rev Nil 14.12.2007 1 of 8

Overview of DWDM

Definition Dense wavelength division multiplexing (DWDM) is a fiber-optic transmission technique that employs light wavelengths to transmit data parallel-by-bit or serial-by-character.

Overview This tutorial addresses the importance of scalable DWDM systems in enabling service providers to accommodate consumer demand for ever-increasing amounts of bandwidth. DWDM is discussed as a crucial component of optical networks that allows the transmission of e-mail, video, multimedia, data, and voice—carried in Internet protocol (IP), asynchronous transfer mode (ATM), and synchronous optical network/synchronous digital hierarchy (SONET/SDH), respectively, over the optical layer.

1. The Challenges of Today's Telecommunications Network

To understand the importance of DWDM and optical networking, these capabilities must be discussed in the context of the challenges faced by the telecommunications industry, and, in particular, service providers. Most U.S. networks were built using estimates that calculated bandwidth use by employing concentration ratios derived from classical engineering formulas such as Poisson and Reeling. Consequently, forecasts of the amount of bandwidth capacity needed for networks were calculated on the presumption that a given individual would only use network bandwidth six minutes of each hour. These formulas did not factor in the amount of traffic generated by Internet access (300 percent growth per year), faxes, multiple phone lines, modems, teleconferencing, and data and video transmission. In fact, today many people use the bandwidth equivalent of 180 minutes or more each hour.

Therefore, an enormous amount of bandwidth capacity is required to provide the services demanded by consumers. At the transmission speed of one Gbps, one thousand books can be transmitted per second. However today, if one million families decide they want to see video on Web sites and sample the new emerging video applications, then network transmission rates of terabits (trillions of bits per second [Tbps]) are required. With a transmission rate of one Tbps, it is possible to transmit 20 million simultaneous 2-way phone calls or transmit the text from 300 years–worth of daily newspapers per second.

In addition to this explosion in consumer demand for bandwidth, many service providers are coping with fiber exhaust in their networks. Today, many carriers are nearing one hundred–percent capacity utilization across significant portions of their networks. Another problem for carriers


is the challenge of deploying and integrating diverse technologies in one physical infrastructure. Customer demands and competitive pressures mandate that carriers offer diverse services economically and deploy them over the embedded network. DWDM provides service providers an answer to that demand (see Figure 1).

Figure 1. Optical Transport to Optical Networking: Evolution of the Phototonics Layer

Use of DWDM allows providers to offer services such as e-mail, video, and multimedia carried as Internet protocol (IP) data over asynchronous transfer mode (ATM) and voice carried over SDH. Despite the fact that these format—IP, ATM, and SDH—provide unique bandwidth management capabilities, all three can be transported over the optical layer using DWDM. This unifying capability allows the service provider the flexibility to respond to customer demands over one network.

A platform that is able to unify and interface with these technologies and positions the carrier with the ability to integrate current and next-generation technologies is critical for a carrier's success.

2. Resolving the Capacity Crisis

Faced with the multifaceted challenges of increased service needs, fiber exhaust, and layered bandwidth management, service providers need options to provide an economical solution. One way to alleviate fiber exhaust is to lay more fiber, and, for those networks where the cost of laying new fiber is minimal, this will prove the most economical solution. However, laying new fiber will not necessarily enable the service provider to provide new services or utilize the bandwidth management capability of a unifying optical layer.

A second choice is to increase the bit rate using time division multiplexing (TDM), where TDM increases the capacity of a fiber by slicing time into smaller intervals so that more bits (data) can be transmitted per second (see Figure 2). Traditionally, this has been the


industry method of choice (STM–1, STM –4, STM –16, etc.). However, when service providers use this approach exclusively, they must make the leap to the higher bit rate in one jump, having purchased more capacity than they initially need. Based on the SDH hierarchy, the next incremental step from 10 Gbps TDM is 40 Gbps—a quantum leap that many believe will not be possible for TDM technology in the near future. This method has also been used with transport networks that are based on the synchronous digital network (SDH) standard for international networks.

Figure 2. Increased Network Capacity—TDM

The telecommunications industry adopted the SDH standard to provide a standard synchronous optical hierarchy with sufficient flexibility to accommodate current and future digital signals. SDH accomplishes this by defining standard rates and formats and optical interfaces. For example, multiple electrical and optical signals are brought into a SDH terminal where they are terminated and multiplexed electrically before becoming part of the payload of an STM–1, the building block frame structure of the SDH hierarchy. The STM–1 payloads are then multiplexed to be sent out on the single fiber at a single rate: STM-4 to STM-16 to STM-64 and eventually to STM-256.

SONET and SDH, two closely related standards, provided the foundation to transform the transport networks, as we know them today. They govern interface parameters; rates, formats, and multiplexing methods; and operations, administration, maintenance, and provisioning (OAM&P) for high-speed transmission of bits of information in flashing laser-light streams. A synchronous mode of transmission means that the laser signals flowing through a fiber-optic system have been synchronized to an external clock. The resulting benefit is that data streams transmitting voice, data, and images through the fiber system flow in a steady, regulated manner so that each stream of light can readily be identified and easily extracted for delivery or routing.

3. Capacity Expansion and Flexibility: DWDM

The third choice for service providers is dense wavelength division multiplexing (DWDM), which increases the capacity of embedded fiber by


first assigning incoming optical signals to specific frequencies (wavelength, lambda) within a designated frequency band and then multiplexing the resulting signals out onto one fiber. Because incoming signals are never terminated in the optical layer, the interface can be bit-rate and format independent, allowing the service provider to integrate DWDM technology easily with existing equipment in the network while gaining access to the untapped capacity in the embedded fiber.

DWDM combines multiple optical signals so that they can be amplified as a group and transported over a single fiber to increase capacity (see Figure 3). Each signal carried can be at a different rate and in a different format (SDH, ATM, data, etc.) For example, a DWDM network with a mix of SDH signals operating at 2.5 Gbps and 10 Gbps over a DWDM infrastructure can achieve capacities of over 40 Gbps. A system with DWDM can achieve all this gracefully while maintaining the same degree of system performance, reliability, and robustness as current transport systems—or even surpassing it. Future DWDM terminals will carry up to 80 wavelengths of STM-16, a total of 200 Gbps, which is enough capacity to transmit 40,000 volumes of an encyclopedia in one second.

Figure 3. Increased Network Capacity—WDM

The technology that allows this high-speed, high-volume transmission is in the optical amplifier. Optical amplifiers operate in a specific band of the frequency spectrum and are optimized for operation with existing fiber, making it possible to boost light wave signals and thereby extend their reach without converting them back to electrical form. Demonstrations have been made of ultra wideband optical-fiber amplifiers that can boost light wave signals carrying over 100 channels (or wavelengths) of light. A network using such an amplifier could easily handle a terabit of information. At that rate, it would be possible to transmit all the world's TV channels at once or about half a million movies at the same time.

Consider a highway analogy where one fiber can be thought of as a multilane highway. Traditional TDM systems use a single lane of this highway and increase capacity by moving faster on this single lane. In


optical networking, utilizing DWDM is analogous to accessing the unused lanes on the highway (increasing the number of wavelengths on the embedded fiber base) to gain access to an incredible amount of untapped capacity in the fiber. An additional benefit of optical networking is that the highway is blind to the type of traffic that travels on it. Consequently, the vehicles on the highway can carry ATM packets, SDH, and IP.

4. Capacity Expansion Potential

By beginning with DWDM, service providers can establish a grow-as-you-go infrastructure, which allows them to add current and next-generation TDM systems for virtually endless capacity expansion (see Figure 4). DWDM also gives service providers the flexibility to expand capacity in any portion of their networks—an advantage no other technology can offer. Carriers can address specific problem areas that are congested because of high capacity demands. This is especially helpful where multiple rings intersect between two nodes, resulting in fiber exhaust.

Figure 4. Capacity Expansion Evolution: A Strategy for the Long Term

Service providers searching for new and creative ways to generate revenue while fully meeting the varying needs of their customers can benefit from a DWDM infrastructure as well. By partitioning and maintaining different dedicated wavelengths for different customers, for example, service providers can lease individual wavelengths—as opposed to an entire fiber—to their high-use business customers.

Compared with repeater-based applications, a DWDM infrastructure also increases the distances between network elements—a huge benefit for


long-distance service providers looking to reduce their initial network investments significantly. The fiber-optic amplifier component of the DWDM system enables a service provider to save costs by taking in and amplifying optical signals without converting them to electrical signals. Furthermore, DWDM allows service providers to do it on a broad range of wavelengths in the 1.55µm region. For example, with a DWDM system multiplexing up to 16 wavelengths on a single fiber, carriers can decrease the number of amplifiers by a factor of 16 at each regenerator site. Using fewer regenerators in long-distance networks results in fewer interruptions and improved efficiency.

5. DWDM Incremental Growth

A DWDM infrastructure is designed to provide a graceful network evolution for service providers who seek to address their customers' ever-increasing capacity demands. Because a DWDM infrastructure can deliver the necessary capacity expansion, laying a foundation based on this technology is viewed as the best place to start. By taking incremental growth steps with DWDM, it is possible for service providers to reduce their initial costs significantly while deploying the network infrastructure that will serve them in the long run.

Some industry analysts have hailed DWDM as a perfect fit for networks that are trying to meet demands for more bandwidth. However, these experts have noted the conditions for this fit: a DWDM system simply must be scalable. it is possible for service providers to begin evolving the capacity of the TDM systems already connected to their network. Mature STM-64 systems can be added later to the established DWDM infrastructure to expand capacity to 40 Gbps and beyond.

6. The Optical Layer as the Unifying Layer

Aside from the enormous capacity gained through optical networking, the optical layer provides the only means for carriers to integrate the diverse technologies of their existing networks into one physical infrastructure. DWDM systems are bit-rate and format independent and can accept any combination of interface rates (e.g., synchronous, asynchronous, STM-1, STM-4, STM-16 etc) on the same fiber at the same time. If a carrier operates both ATM and SDH networks, the ATM signal does not have to be multiplexed up to the SDH rate to be carried on the DWDM network. Because the optical layer carries signals without any additional multiplexing, carriers can quickly introduce ATM or IP without deploying an overlay network. An important benefit of optical networking is that it enables any type of cargo to be carried on the highway.

But DWDM is just the first step on the road to full optical networking and the realization of the optical layer. The concept of an all-optical network


implies that the service provider will have optical access to traffic at various nodes in the network, much like the SDH layer for SDH traffic. Optical wavelength add/drop (OWAD) offers that capability, where wavelengths are added or dropped to or from a fiber, without requiring a SDH terminal. But ultimate bandwidth management flexibility will come with a cross-connect capability on the optical layer. Combined with OWAD and DWDM, the optical cross-connect (OXC) will offer service providers the ability to create a flexible, high-capacity, efficient optical network with full optical bandwidth management. These technologies are today's reality: DWDM has been utilized in the long-distance network since 1995, OWAD will be available in products in 1998, and the first OXC was showcased at industry conventions in 1997.

7. Key DWDM System Characteristics

There are certain key characteristics of acceptable and optimal DWDM systems. These characteristics should be in place for any DWDM system in order for carriers to realize the full potential of this technology. The following questions help determine whether a given DWDM system is satisfactory.

Does the system reuse embedded equipment and fiber plant?

DWDM systems at 2.5 Gbps should use the full capability of the embedded equipment and fiber base.

Is the system robust and reliable?

Well-engineered DWDM systems offer component reliability, system availability, and system margin. Although filters were often susceptible to humidity, this is no longer the case.

Do the pump lasers have connectors, or are they spliced in the optical amplifier?

An optical amplifier has two key elements: the optical fiber that is doped with the element erbium and the amplifier. When a pump laser is used to energize the erbium with light at a specific wavelength, the erbium acts as a gain medium that amplifies the incoming optical signal. If a connector is used rather than a splice, slight amounts of dirt on the surface may cause the connector to become damaged.


Is manual intervention required when adding or removing channels?

Automatic adjustment of the optical amplifiers when channels are added or removed achieves optimal system performance. This is important because if there is just one channel on the system with high power, degradation in performance through self-phase modulation can occur. On the other hand, too little power results in not enough gain from the amplifier.

Does the system use fluoride- or silica-based fiber amplifiers?

In the 1530- to 1565-nm range, silica-based optical amplifiers with filters and fluoride-based optical amplifiers perform equally well. However, fluoride-based optical amplifiers are intrinsically more costly to implement. The long-term reliability of fluoride-based fibers has not yet been verified.

Can the system's number of wavelengths and bit rate be upgraded?

While the answer is yes for all DWDM systems, planning for this is critical. If service providers put together their networks in a specific way and then want to upgrade, one of two things must happen: They need either more power or additional signal-to-noise margin. For example, each time providers double the number of channels or the bit rate, 3 dB of additional signal-to-noise margin is needed.

Does the system offer standards-compliant maintenance interfaces?

Standard transaction language 1 interfaces are widely available for DWDM systems. Interfaces should readily fit into a service provider's typical maintenance scheme.

8. Conclusion

Optical networking provides the backbone to support existing and emerging technologies with almost limitless amounts of bandwidth capacity. All-optical networking (not just point-to-point transport) enabled by optical cross-connects, optical programmable add/drop multiplexers, and optical switches provides a unified infrastructure capable of meeting the telecommunications demands of today and tomorrow. Transparently moving trillions of bits of information efficiently and cost-effectively will enable service providers to maximize their embedded infrastructure and position themselves for the capacity demand of the next millennium.

Section-II

Chapter-II

DWDM system engineering & planning

E3E4 DWDM Sys Engg & Plg Rev Nil 14.12.2007 1 of 6

DWDM system engineering & planning

1. Objective:- DWDM system engineering & planning is basically to create awareness of system engineering as well as of used by the planners. There is no planning for fresh DWDM ring in BSNL at present. The planning of DWDM equipment is being done on congestion of STM-16 ring capacity further we are facing the problems of exhausting the fiber in our OF cable and there fore it is not possible to install more number of SDH, STM-16.

2. Equipment nomenclature / application code:- For system engineering

basic tool, the first requirement is to learn how to read the system code. The system code is given as follows

nWx-y.z

where for each application code n is the maximum number of wavelength. It means the number of channels. For example 16channel system. 32 channel system or higher capacity system.

W. is the letter indicating span distance. This is divided L. indicating long haul V. Indicating very long haul U. Indicating ultra long hauls. X. is the maximum number of spans allowed within the application code

with or without line amplifier. The deployment. of line amplifier is depend upon the various important parameters of EDFA and fiber types.

y is the maximum bit rate (STM level) on each DWDM wavelength (channel) .Maximum bit rate per wavelength depends upon type of fiber as given below in brief . z is the fiber type, as follows.

2 indicating G.652 fiber 3 indicating G. 653 fiber] 5 indicating G 655 fiber

For example. nWx-y.z 32.L.8.2.5Gbs.2 Where n(n is the maximum number of wavelength)=32 w=L( long haul system) x(is the maximum number of spans)=8 y(y is the maximum bit rate)=2.5Gbs. z(z is the fiber type)=G.652.

the maximum bit rate per channel for G.652 fiber for targeting spans distance 80Km is 2.5 Gbs ( STM-16) only.


3. No of spans/ section with Optical Line Amplifier (OLA) In long haul maximum number of 8 section or 7 line amplifier maybe deployed for the maximum optical reach distance, in this case is 640 Km. In very long to haul type deployment maximum number of 3 section or 2 line amplifier may be placed in route. Ultra long haul system dose not support any EDFA therefore as present BSNL has no planning for deploying ultra long haul system in BSNL network. In between long haul and very long haul, some verdure are supporting medium long haul system with 5 sections. & 4 line amplifier G-692- suggested channel central frequency spacing for application on G.652/G.655 80 Kms 8*22db OBA OLA OPA 5*30db 100 Kms OBA OLA OPA 3*33db 120 Kms OBA OLA OPA 1*37db 160Kms OBA OPA For example: the long haul deployment of EDFA is discussed below Maximum span distance is 80 Kms. The maximum transmission loss per section is 22 db. The maximum link distance for DWDM link is 640 Kms with spans of 80 Kms each.. The assumptions are as follows; Fiber alternation including splice loss, connector loss etc. in IIIrd window is taken 0.28-db/ Km 0.28 x 80 = 22.40 db For G.652 fiber, the dispersion for maximum link distance of 640 Km is 12800 ps/nm The G.652 fiber cable affer 20 ps /km dispersion. There for 640 Kms dispersion is 640 x 20=12800 ps/nm. If be consider lowest RX level as 21 db, than only 1db mtce margin is there.

•Mixed networking is possible * Based on G.652, 0.275 db/km, 20ps/nm. km


At present rout condition, to restore the cable fault normally a piece of cable is placed. Therefore instead of 1 joint double joint has to be made. So mtce margin should be more.

4 Wavelength Grid:

In BSNL, only G.652 fiber cable has been laid in our network. Therefore it is recommended a minimum of 100 Ghz frequency spacing ( 0.8 nm spacing ) maximum up to 40 channel are to be deployed

One of the key element of DWDM system is optical fiber amplifier. Erbium

Doped Fiber Amplifier (EDFA) is the most common commercial available amplifier telecom industry. Most of the EDFA are available commercially working on C band with range of 1530-1565 nm only. The different wavelength sources (LASER) as finalized by ITU-T only shall be used with a central wavelength frequency 193.1 Thz. For 16 channel DWDM system, the channel spacing is 200 Ghz. Further spacing is half i.e. 100 Ghz for 32 channel DWDM system. In general as the number of channel is increased, inter channel spacing is narrowed.

G-692- suggested channel central frequency spacing for application on

G.652/G655 Fibbers: Channel Number Frequency ( Thz) Wavelength in nm 1 192.1 1560.61 2 192.2 1559.79 3 192.3 1558.98 4 192.4 1558.17 5 192.5 1557.38 6 192.6 1556.55 7 192.7 1555.58 8 192.8 1554.94 9 192.9 1554.13 10 193.0 1553.33 11 193.1 1552.52 12 193.2 1551.72 13 193.3 1550.92 14 193.4 1550.12 15 193.5 1549.32 16 193.6 1548.51 17 193.7 1547.72 18 193.8 1546.92 19 193.9 1546.12 20 194.0 1545.32 21 194.1 1544.63 22 194.2 1543.73 23 194.3 1542.94 24 194.4 1542.14 25 194.5 1541.35


26 194.6 1540.56 27 194.7 1539.77 28 194.8 1538.98 29 194.9 1538.19 30 195.0 1537.40 31 195.1 1536.61 32 195.2 1535.82

To utilized available resources in BSNL network, the following are the key tools for design consideration of DWDM system planning

1. Fiber type 2. Transmit power and Receiver sensitivity. 3. Amplifier spacing. 4. Inter channel spacing 5. Number of wavelength.

5. Data for planning A. Identification of DWDM Routs as per traffic requirement:-

1. Identification of routes should normally be done with more than 60% load. The number of fiber loaded on this cable should be at least 50% in cases of 12 fiber OF cable.

2. The present Band Width requirement for various services should be taken into

account. To calculate the anticipated bandwidth for further, we should consider growth of B.W demand in the past for two years and we should also focus on new services likely to be introducing in the network. In general bandwidth requirement gets normally double after every alternate year. Planning should take care for at least 10 year of equipment life. We should also consider working systems on the routes. At least 2 no. of STM-16 system or more than 2 systems should be working on the chosen route for DWDM deployment.

B. Rout planning:

The planning of DWDM systems is being done on our existing nationals/ regional SDH rings. On our existing cable route, a meaning full survey needs to be done for ascertaining for fiber capacity utilized and to find out good spare fiber also. For calculation of losses per section, the losses at IIIrd window i.e. 1550nm should be measured for all section. The distance of each section i.e. From ADM to ADM or ADM to Repeater should also be measured and put in table form for each proposed plan DWDM link along with section transmission losses. The due consideration should be focused on present add/ drop traffic at various locations and further add/drop requirement on the basis of geographical and financial implications. Development of a systematic layered architect should be also consider for further proof network..


6. Planning elements for DWDM system: Two type of DWDM systems for available in telecom industry.

1. Open system i.e transponder based system. 2. Integrated system i.e non-transponder based system.

Fresh equipment including SDH equipment can be planned only with integrated non-

transponder based system. In this type of system SDH ADM laser wavelength is as per ITU – T prescribed wavelength grid. Since open system also with open door to use existing SDH/PDM/ATM equipment etc. and open system is also welcome new services without SDH network. Therefore we should plan only open DWDM. System in our BSNL network.

Since at present the BSNL network is based or G.652 fiber, so we can plan only

maximum 32-channel equipment with 2.5 Gbs with bit rate per channel. However we can plan least 12 number of transponder initially the vender should be asked to supply more transponder as and when required as per traffic need by placing a clause in tender document. Keeping in new of repeater spacing, present/ Future - add/Drop requirement, geoghariical condition, the planning of long haul, medium long haul and very haul system can be done. Even in one link mix planning is also possible. With G655 fiber, OF cable we can plane systems of 160 channels in C band with 10 Gbs per channel bit rate also


7. Survivability requirement in DWDM network After considering due optical parameter in the link engineering and because of 640 Kms limit of optical reach distance on G.652 fiber it be not possible to convert all SDH rings in to DWDM optical rings. Therefore best-suited topology for our network is:

1. DWDM: Point to Point 2. DWDM: Point to Multi Point

However we can plan some optical DWDM link by deploying Optical Add Drop Multiplexes (OADM) in our network to add /drop of limited number of wavelength in between point-to-point deployment. (This is nothing but Point to multi Point deployment topology). 3. SDH : Ring

4. Ultimately Mesh topology with help of Optical cross Connects . Since due to deployment of DWDM equipment point to point or point to multi point it is not offering any optical protection for route failure or equipment failure. However SDH protection (Ms- BSHR-2fiber ring) on our STM-16 rings is successfully offing protection in case of route failure or equipment failure as per features available in SDH network Survivability. 8. Conclusion: The success of planning is depending upon the following important parameter.

1. Planning should be done always in advanced. 2. Planning should be based on present and futures authentic value added data.

3. Planning should be executive always in time with definite time frame.

4. the success of any project is always depend upon the amount of investment and due

return from the project.

Section-II

Chapter-3

DWDM Measurements & Testing Instruments

E3E4 DWDM Testing Rev Nil 14.12.2007 1 of 11

Dense Wavelength Division Multiplexed (DWDM) Testing

Definition

At its simplest, a dense wavelength division multiplexed (DWDM) system can be viewed as a parallel set of optical channels, each using a slightly different light wavelength, but all sharing a single transmission medium. This new technical solution can increase the capacity of existing networks without the need for expensive equipment and can significantly reduce the cost of network upgrades.

Overview

DWDM systems offer an attractive, cost-effective way for the telecommunications industry to expand network bandwidth. This new technology allows telecom operators to meet ever-growing requirements for new services and have greater flexibility in the provision of these services. By allowing fiber-optic links, both existing and new, to carry several channels simultaneously, DWDM makes optimum use of facilities, easily reaching transmission capabilities four to eight times those of traditional time division multiplexed ('1'DM) systems and offering even greater potential capacities.

The planning, installation, and maintenance of DWDM networks demand that much closer attention be paid to a number of limiting performance parameters than has been the case until now This tutorial discusses these parameters as well as other factors involved in field-testing DWDM systems.

Topics

1. The Need for New Testing Tools 2. Spectral Measurements 3 Parameters to be measured in the Field 4 Optical Spectrum Analyzer 5 OSA Characteristics 6. Wavelength Meter 7. New Requirements for Traditional Fiber-Optic Test Instruments 8.Characterizing Fiber for DWDM Applications

9. Field Testing DWDM Systems 10.. Conclusion

1. The Need for New Testing Tools

Although both designing and implementing DWDM systems calls for considerably more care than has been needed for conventional systems, by and large, the skill and capability necessary has increased to a degree: existing knowledge bases and facilities, with some additional training and upgraded instrumentation, will meet the challenges that the new technology presents. However, the same cannot be said for field testing. New parameters must be measured, and component characteristics once of interest only before installation must now be verified regularly. In addition, accuracy and stability requirements reach new levels, and an entirely new dimension—wavelength—must be considered. Field test equipment suitable for troubleshooting in single wavelength systems cannot cope with these needs. New instrumentation is urgently required.


Testing and troubleshooting single-wavelength systems in the field can be accomplished by monitoring a few well-defined parameters. For example, optical power loss, or attenuation, has always been a key factor in the performance of fiber-optic links, and portable optical loss test sets have been developed to measure this loss in the field. Instruments with optical time domain reflectometric capabilities have been developed to locate faulty elements in a link. As system sophistication has grown, so has the significance of optical return loss, especially in the CATV Meld, IA here source-laser instability caused by reflected energy can have serious effects on signal quality. Field instrumentation has been developed to monitor this parameter as well. All this test equipment is still required in the DWDM environment, but with much more stringent needs of WDM. In the fiber itself, both chromatic and polarization mode dispersion spread signal pulses and set limits on the transmission capacity, and their effects may he severe on the transmission signal integrity. New instrumentation capabilities may be needed to identify the sources of these disturbing influences and ensure that they do not adversely affect performance.

2. Spectral Measurements

The major new requirement in the test and monitoring of DWDM systems is the need to characterize components and link accurately as a function of wavelength. Instrumentation to do so already exists—the optical spectrum analyzer (OSA) has long been a fixture in network development and test laboratories. Now, however, similar capabilities must be provided in the field. Capabilities must be usable for maintenance personnel working in conditions that are very different from those in the stable, controlled laboratory environment. Major advances in instrumentation engineering are needed to take measurement capabilities that were once available only in a laboratory out into the field (see Figure 2).

Figure2 DWDM Critical System parameters

5/19/2007 DWDM/ALT/TX-I/Opti.Test/06 9

3.Parameters to Be Measured in the Field

The core measurement capabilities needed in the spectral domain include the following:

• Channel power—One must be able to measure the optical power in each channel to verify the equal distribution of power over the bandwidth of the optical amplifiers (EDFAs) that are used in the link (i.e., to measure the spectral uniformity of the optical power).


• Channel center wavelength and spacing--The precise value of the center wavelength of each channel must be measured in order to detect unacceptable drifts in DFB laser sources.

• Signal-to-noise ratio—This is one of the most important parameters to be measured for each channel in a DWDM system, as it is the best indicator of the overall performance of the channel. The noise measurement it incorporates must be based on measurements of the noise floor between channels.

• Cro ss ta lk . This parameter reveals the level of unwanted signal (noise plus contribution from other channels) in the pass band of the tested channel. It is awkward to incorporate its measurement into field tests because it is a two-step operation, but it can be critical.

• Total optical power—Because adverse effects of non-linear phenomena in the optical fiber depend on the total power carried, the parameter must be measured by summing individual channel powers.

4. The Optical Spectrum Analyzer

Although by its very nature the laboratory-based optical spectrum analyzer meets the new testing requirement for measurements as a function of wavelength, present-day OSA versions are entirely unsuited to field use. Large and heavy, laboratory OSAS are not packaged for portability. The sophisticated optics they contain make them extremely vulnerable to shock and in frequent need of realignment and re-calibration. Their proper use requires a high degree of operator skill. (see Figure 3).

Figure 3. Traditional Optical Spectrum Analyzer Design, Single Pass Monochromater

Producing an OSA that is small, rugged, and reliable enough to be carried about in the field and to be operated by technicians lacking extensive experience with laboratory OSAs is a challenge whose resolution involves the following three steps:

1. Eliminating the features and capabilities of laboratory instruments not required for the maintenance of DI1'DM networks (e.g., spectral measurement abilities outside the EDFA wavelength region)

2. Selecting and developing an optical configuration that can withstand shock and operate without the delicate mechanical displacements used by conventional single-pass and double-pass monochromater designs (see Figure 4) Simplifying


the traditional, complex, laboratory oriented user interface to accommodate the needs of the field operator.

Figure 4. Narrowband, Shock-Resistant OSA Design

5. OSA Characteristics

Characteristics essential to a field version of an OSA, while measuring the core parameters already identified, include the following:

• Dynamic range—An adequate dynamic range—the ability to measure weak signals in the presence of strong ones—is needed to measure the power in a strong, non-saturated signal and that of the adjacent noise floor (in a specified bandwidth). For example, in a system with too GIIz (0.8 nm) channel spacing, an OSA must be able to measure an optical signal at a given wavelength and, just 0.4 nm away, an ASE noise level that may be 30 dB to 35 dB weaker (see Figure 5).

Figure 5. Dynamic Range Calculation for an Optical Spectrum Analyzer

• Optical sensitivity—The instrument sensitivity—the lowest signal level it can quant4—is generally determined by electronic considerations (the dark current of detectors, noise in detector preamplifiers, etc.). It must be low enough to permit the measurement of component insertion loss and assess the signal-to-noise ratio in all parts of a network.

• Resolution bandwidth—The resolution bandwidth of an OSA determines its ability to deal with close optical channel spacing. It is measured as the width of the response curve at half peak power (i.e., 3 dB down) of the instrument to a

Fiber

Detector

Aperture

Diffraction Grating


monochromatic test signal. It is often called full-width half-maximum (FWHM) (see Figure 6).

Figure 6

Resolution Bandwidth

3dB

Resolution Bandwidth Calculation Resolution Bandwidth Calculation for an OSAfor an OSA

AA BB

Wavelength (nm)Wavelength (nm)

Power (Power (dBmdBm))

•

Wavelength accuracy—This is without doubt the shortcoming of the optical spectrum analyzer. Good absolute wavelength accuracy requires the perfect positioning of the grating, which is difficult to do with rotational mechanisms. However, the precision of OSAs gives them the ability to detect unacceptable relative drifts in DFB laser sources. Outboard calibration options such as acetylene absorption cells can be used to improve absolute accuracy to a level acceptable for many other DWDM test applications (see F i g ure 7).

Resolution Bandwidth

3dB

OSA Absolute WavelengthOSA Absolute WavelengthAccuracyAccuracy

AA BB



. .

Although complete redesign of the traditional USA is needed before its capabilities can be offered to field personnel faced with the difficult task of maintaining and troubleshooting DWDM networks, its potential advantages in measuring appropriate parameters make the USA the leading candidate to dominate the DWDM test field. The OSA offers, in a single package, virtually all the test capabilities needed, but many steps must be taken to simplify the hardware and make it rugged, as well as to provide the one-button test procedures, auto-diagnostic functions, and easy approaches


6. The Wavelength Meter

The interferometer-based wavelength meter is used in the laboratory to make accurate, repeatable measurements of source wavelengths. Such measurements are often needed in DWDA4 systems, in particular to check the center wavelengths and the drift characteristics of each of the transmitted optical channels. Although the intrinsic accuracy of about o.00i nm that such instruments attain in the laboratory is entirely adequate to characterize DWDM components, providing comparable capabilities in field instruments—including such features as internal wavelength-reference sources and fast-fourier transform (FFT) processing for de convolution—is a design and engineering challenge of considerable magnitude (see Figure 8). Nevertheless, the wavelength meter is expected to be the instrument of choice for such DWDM tasks as accurately measuring the center wavelengths of distributed feedback lasers and monitoring how they change with time (both short-term and long-term), temperature, and other environmental conditions. Among the characteristics that are particularly important in a field version of a wavelength meter are the following:

Movablemirror

Detector

Beam splitter

Fibre

Fixed mirror

Traditional Wavelength MeterTraditional Wavelength Meter

• Absolute wavelength accuracy—The ability to accurately measure the absolute wavelength of a channel is the strongest attribute of this type of instrument. With the help of an interferometer, which is usually both precise and accurate in wavelength, the absolute accuracy of the wavelength meter should be better than about 0.005 nm, adequate to locate individual DWDM channel wavelengths.

• Absolute power accuracy—The ability to measure the exact power in each DWDM channel is important to verify the power flatness throughout the link. Using a wave meter, the actual power in each channel can be determined through use of the FFT calculation to an accuracy. The resulting absolute power accuracy will usually be


a little lower than that OSA (see of the Figure 9).

Wavelength and Power AccuracyWavelength and Power Accuracy



Power accuracy

Wavelength meter measurement window

Good wavelength accuracy

• Dynamic range—The ability to measure weak signals in the presence of strong ones, dynamic range is required—as it is in the OSA—to measure the noise floor in a multi channel transmission system. The wavelength meter can attain a dynamic range of 20 dB to 25 dB for characterization of DWDM channels.

• Number of channels—The number of channels the instrument can extract depends on the mechanical precision of the interferometer and on the extraction capacity of the FF'I' algorithm used. Forty to a hundred channels should be attainable, enough to characterize DWDM systems properly.

The wavelength meter's strength in absolute wavelength measurement enhances the OSA and is an excellent complementary instrument for the complete characterization of DWDM systems. Furthermore, certain field operations determining DFB center wavelengths and troubleshooting lasers, in particular require the accuracy that the wavelength meter provides.

Once again, the challenge is to modify present wavelength meters, which are intended for use in the laboratory, to make them suitable for the demanding DWI)M field environment. The new field wavelength meter will have to be rugged and portable and will have to offer simple and—to as great a degree as possible automatic test procedures.

7. New Requirements for Traditional Fiber

Optic Test Instruments

In addition to instrumentation specifically designed for the maintenance of DWI)M systems (i.e., the new OSAs and wavelength meters whose characteristics have been outlined elsewhere in this tutorial), conventional field installation and test equipment must also be considered because of the strong influence that some of the properties of fiber-optic links have on DWDM transmission. Although many of the basic attributes of these links are independent of the transmission mode used (TDM or WDM) and can thus be measured


using conventional instruments, a few parameters arc critical to proper DWDM operation, and special care must be taken in selecting field instruments to measure them.

Optical Loss Test Sets (OLTS)

Because of the use of several channels at different, precisely defined wavelengths, dedicated WDM power meters must be calibrated at specified wavelengths in the 1530 nm to 1565 nm band, in order to measure the power in individual channels at the output of demultiplexers. Optical loss test sets will also be used at the wavelengths used for optical supervisory channels (OSC)—1480 nm, 1510 nm, and 1625 nm, depending on the system design. Dedicated DFB light sources will be needed to verify the loss budget when the fiber is installed. The longest OSC wavelength, 1625 nm, requires particular attention since this wavelength lies outside the range in which the fiber or cable manufacturer guarantees the performance of its product. Optical loss test sets specifically intended for this wavelength can be expected to reach the market soon.

Optical Time Domain Reflectometer

A clear tendency is emerging in the OTDR world to offer capabilities in the fourth window spectral region, at 1625 nm. In addition to the ability to test and troubleshoot the important 1625 nm optical supervisory channel, using this wavelength presents other important advantages. In particular, in many circumstances, live fibers may be tested at the 1625 nm wavelength while normal DWDM transmission continues uninterrupted in the F.DFA spectral region. Because optical losses due to fiber bending are more pronounced at 1625 nm than at the shorter DWDM operational wavelengths, OTDR testing at the long wavelength can reveal critical points in the installed fiber—places where the performance of the fiber is acceptable at the time of installation but could degrade over time (see Figure 1o).

B e n d in g L o s s C o m p a r is o n a t 1 3 1 0 n m , 1 5 5 0 n m a n d 1 6 2 5 n m

Back Reflection Meter

In a conventional (non-WDM) network, the optical return loss (ORL) can be determined with a single measurement using a back reflection meter at the operating wavelength. In DWDM system there are two possibilities: an aggregate measure covering the entire wavelength band in use or a detailed one, giving result for each channel wavelength. Although the first is obviously quicker to perform and may provided enough information to satisfy a go/no-go acceptance test, ORL can vary considerable from channel to channel. This ORL variation with wavelength may be caused by defective Bragg gratings or, more often, from bad connectors at the output port of a multiplexer or demultiplexer. Excessive


back reflection can cause instability in DFB source lasers, thereby affecting the overall system performance. As result, an ability to perform the more complex wavelength depended measurement will often be needed.

An aggregate measurement is made with a broadband source and as independent power meter in the same way the measurement is carried out in a single wavelength optical link. The measurement result is single value- the total ORL power at the test point, over the entire transmission spectrum. The value of the ORL as a function of wavelength is often a more useful parameter intrinsically, and its determination may be essential of the simpler aggregate test should fail on a particular link. It is measured using a high-power broadband source, usually an erbium-amplified spontaneous emission (ASE) source. High power is needed to provide enough power in each measurement band, which nay be as little as 0.1nm wide, to give an adequate is an optical spectrum analyzer of adequate resolution and sensitivity. The result, of course, is an individual ORL reading often just the information needed to guide a troubleshooting session- for each DWDM channel (see Figure 11).

8. Characterizing Fiber for DWDM

Theory predicts—and field experience confirms—that the characteristics of the fiber itself can have significant impact on the performance of DWDM networks and that the particular characteristics, which are most important, are not necessarily those of greatest concern in conventional single-wavelength links.

Chromatic Dispersion

Chromatic dispersion, the variation of the index of refraction of the fiber with wavelength, can be a critical determinant of system performance in DWDM systems, especially those that use a judiciously selected amount of dispersion to minimize certain undesirable nonlinear effects in the fiber itself. Its value is determined during fiber manufacture, however, and few situations have arisen in which it is necessary to verify this value in the field.

As DWDM systems are operated ever closer to their limits, however, a need is likely to emerge to verify that this parameter is adequately controlled at every point in the optical path. The eventual development of field instrumentation to measure chromatic dispersion is likely, especially if the management of chromatic dispersion on installed fiber turns out


to be more complex than expected.

Polarization Mode Dispersion

Polarization mode dispersion (PM D), in which various polarization states of the optical signal propagate at different velocities, is especially difficult to deal with. Its effects prevent many present-day optical systems from using high-bandwidth transmission equipment meeting stm-64 specifications. Since current state-of-the-art DWDM technology offers eight such stm-64 channels, where the fiber can support the rate, PM 1) can he a serious limitation to system performance and to prospects for upgrading that performance.

PMD affects the transmission quality by spreading signal pulses and, therefore, raising the bit error rate (HER) of the system. It arises in the first place because of asymmetries in the fiber itself, so the primary remedy must be applied at the manufacturing level. But the damage does not necessarily end there. During installation, the fiber can be crushed, kinked, or otherwise overstressed. Environmental and climatic changes can also affect its circular geometry and thus worsen its PMD characteristics. Post-installation testing may be needed to ensure that a network does not overly suffer from PMD and that the installed facilities can be upgraded to support tomorrow's higher bit rates. (See Figure 12)

Second-order PMD, the variation of polarization mode dispersion with wavelength, is considered to have a negligible effect on network performance. However, it acts as a completely random contribution to the network's chromatic dispersion, possibly negating deliberate steps taken in network design to provide the exact amount of this dispersion to reduce nonlinear disturbances in signal propagation. Although this parameter bears watching, its long-term importance cannot yet be predicted.

9. Field Testing DWDM Systems

As previously indicated, the implementation of DWDM transmission systems in the field on a large scale will have a major impact on each level of installation and system verification. New skills will have to be developed to face these new challenges, and exiting test instrumentation will require adaptation. Nevertheless, one instrument emerges as the apparent reference DWDM system characterization tool- the option spectrum analyzer.

The optical spectrum analyzer is eminently suited to almost all the field testing needed in DWDM systems: measurements of signal levels, signal-to-noise ratio, cross talk as well as


channel spacing and stability. The graphic presentation of modern OSA instrument, clearly showing how the parameter of interest varies with wavelength, gives and excellent overview

of many of the phenomena crucial to the proper operation of DWDM network and valuable clues for the subsequent investigation of any problems that the measurement might reveal. Nevertheless, in many contexts is offers too much information and often not the specific information the field maintainer or troubleshooter needs. Operating and readout procedures and tools must be greatly simplified from those appropriate to laboratory OSA if the instrument is to be cost- effective in the field

However, to complement OSA testing in the field, center wavelength must be accurately measured. This parameter can be important, especially if the system under study is part of a large one whose standards must be respected. Other instrumentation offering more accurate wavelength calibration-a wavelength meter, most likely-is also needed for such operation as the measurement of DBF characteristics.

10. Conclusion

Any telecommunication service provider who operates or installs DWDM system must meet testing requirements well beyond those needed for older-generation equipment and must be prepared t o perform sophisticated testing in the field on existing line and equipment laboratories, now must be considered.

Throughout the life cycle of a network, from planning through installation to routine maintenance. These new requirements will inevitably lead to the development of new field test instruments tailored for use in DWDM systems. The core of this new instrumentation suite—the reference test instrument—is likely to be the optical spectrum analyzer because of its ability to perform most of the measurements needed for system characterization, maintenance, and troubleshooting.

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E3E4 Next Gen SDH Rev Nil 14.12.2007 1 of 6

OVER VIEW OF NEXT GENERATION SDH

Since the turn of 20th centaury, the telecommunication has switched over from the traditional voice transport to data transport. Though digitized voice is still a very large contributor for bandwidth as wall as for revenue. Therefore instead of an evolution of the existing transport standard, a revolution is necessary to cope up additional data transport. This revolution is the justification for the title of the article Overview Of next Generation SDH. During the evolution of digital multiplexes, e.g. from the primary rate multiplexes 2048kbit/s E1 and 1544kbit/s DS1 up to the fourth order multiplexes 139.264 Mbit/s E4 and 274.176 Mbit/s DS4, referred as Pleisiochronous Digital Hierarchy (PDH) signals, improved network synchronization and better Operations, Administration and Maintenance (OA&M) has become necessary. The OA&M structure should provide a measure for the better quality the transported signals and a validation of the connection through network. The existing PDH structure could not be used to fulfill this requirement. The revolutionary Synchronous Digital Hierarchy (SDH) and Synchronous Optical Network (SONET) were designed to meet the required improvements. A PDH network has a strong vertical structure and is star shaped. The SDH/SONET network has a strong horizontal structure with ring shaped hierarchical layers and Add/Drop Multiplexes (ADM) providing the interconnection between the layers and connections for client or tributary signals. The first generation SDH/ SONET appeared after the standardization in 1986.

As the PDH multiplexes were designed to transport voice signals and private lines the SDH and SONET multiplex were designed initially to transport the same signals. Because of their nature of multiplexing they are referred to as Time Division Multiplexes (TDM). An additional advantage of the revolutionary design of SDH/SONET is the multiplexing structure where tributary signals are mapped as payload into containers. These containers, together with their own timing information and OA&M overhead, are transported as independent virtual containers in the SDH/SONET network. The multiplex structure of SDH/SONET is also designed to enable the

Evolution to higher order multiplexes to meet the demand for transporting more and more payload. The original structure of SDH is


given as follows

SDH Initial Multiplex Structure

CC

Pointer processing multiplexing

Aligning

Mapping

DS1 E1 DS2 E3/DS3 E4

C-11 C-12 C-2 C-3 C-4

VC-11 VC-12 VC-2 VC-3

TU-11 TU-12 TU-2 TU-3

TUG-2

TUG-3

VC-4

AU-4

AUG-1

STM-1

x4 x3 x1

x7

x1

x3

x3

x1

x1

The ITU-T extended the concept of four times larger payload transport capabilities than the previous multiplex container in SDH/SONET as was prevailing in the PDH. The payload capacity of these new higher order multiplexes

cannot only be used to transport four times the pay load container from the previous multiplex but can also be used to transport a single CONTIGUOUS PAYLOAD CONTAINER. This mythology used is called Concatenation. To provide the increased bandwidth, the solution is only to define the concept of Contiguous concatenation (CCAT) and introducing VCAT in existing networks by using Virtual concatenation (VCAT). It appeared that VCAT could also be used to provide efficiently a matching bandwidth for non-voice related signals The most recent defined application is the deployment of VCAT to enable the gradual introduction of an all-Optical Transport Network (OTN) as an evolution of existing SDH/ SONET. The figure shows SDH extended multiplex structure.


SDH Extended Multiplex Structure

CC

Pointer processing multiplexing

Aligning

Mapping

DS1 E1 DS2 E3/DS3 E4

C-11 C-12 C-2 C-3 C-4

VC-11 VC-12 VC-2 VC-3

TU-11 TU-12 TU-2 TU-3

TUG-2TUG-3

VC-4

AU-4

AUG-1

STM-1

x4 x3

x1

x7

x1

x3

x3

x1

x1

C-4-4c C-4-16c C-4-64C C-4-256C

VC-4-4c VC-4-16c VC-4-64c VC-4-256c

AU-4-4c AU-4-16c AU-4-64c AU-4-256c

AUG-4

AUG-16

AUG-64

AUG-256

STM-4 STM-16 STM-64 STM-256

x4x4

x4

x4

x4

x1 x1 x1 x1

x1 x1 x1 x1

Contiguous Concatenation

Higher order multiplexes

Virtual Concatenation VCAT makes possible to transport pipes to be “right-sized” for various data payloads by allowing SDH/SONET channels to be multiplexed in arbitrary arrangements. VCAT break down data packets and maps them into the base units of TDM frames e.g. , STS-1 (51 Mb/s) for SONET and AU-4 (155Mb/s) for SDH. This data is then grouped in multiple data flows of varying size to create larger, aggregate payloads optimally sized to match available SDH/SONET container capacity. VCAT is used at the end Network Elements of the Link (Intermediate network elements needs not to aware the facility of VCAT), which permits each channel used to be independently transmitted through legacy transport network.. Data is encapsulated using GFP. The ITU standard for VCAT is G.707.


HO-VCAT High- Order Virtual Concatenation High- Order VCAT manipulates data along higher order paths. STS-1/3 for SONET and VC-3/4 for SDH. HO-VAT can be used to transport Gbit Ethernet traffic, can also be used to transport 100 MBit Ethernet traffic. LO-VCAT Lowh- Order Virtual Concatenation Low order VCAT applies concatenation at the lower granular

VT1.5/VC-12 level. LO-VCAT is used to transport lower rate data such as 10/100 MBit Ethernet.

VC Rate Efficiencies

Ethernet (10M) VC3 ��20% VC-12-5v �� 92%

100M Ethernet STM-1= 64 x VC-12

VC-12-5v

VC-12-46v

2x 10M EthernetVC-12-5v

8x E1 Services

Example:

More services integrated- by using VC!

Fast Ethernet (100M) VC-4 ��67% VC-12-46v �� 100%

Data Rates Efficiency w/o VC using VC

Gigabit Ethernet (1G) VC-4-16c �42% VC-4-7v �� 85%

ESCON (200M) VC-4-4c �33% VC-3-4v �� 100%

Fibre Channel (800M) VC-4-16c �33% VC-4-6v �� 89%

LINK CAPACITY ADJUSTMENT SCHEME (LCAS) For the dynamic applications of bandwidth, which can vary in time, the

payload capacity provided by the VCAT is not used efficiently. For the effective utilization, a protocol has been designed to flexibly adjust the payload container size. This protocol in named as LINK CAPACITY ADJUSTMENT SCHEME (LCAS). IN LCAS protocol, the LCAS overheads signals are added to

the virtual concatenation control information. This information is required to provide a flexible and hitless increase or decrease of the payload bandwidth. This core tool can effectively be used to provide bandwidth on demand to users such as Ethernet, Private Lines Customers. This dynamic bandwidth control can also be used by

carriers to provide protection/ Survivability, when network faces any


undesirable problems. LCAS works with VCAT to dynamically allocate bandwidth by reconfiguring VCAT groups in real time. LCAS is bi-directional signaling protocol between network elements that are continuously monitoring a link. This monitoring process ensures that changes in the network capacity do not impair a customer’s traffic transportation. The ITU standard defining LCAS is G.7042. Generic Frame Procedure (GFP).

The major part of IP, Ethernet traffic is transported over the public network by encapsulating it in Frame Relay, Point-to-Point Protocol (PPP), High-Level Data Link Control (HDLC), Packet over SONET/SOH (POS) or Asynchronous Transport Multiplex (ATM). SAN (Storage Area Network) protocols such as Fiber Channel (FC), Enterprise Systems Connectivity (ESCON) and Fiber Connectivity (FICON) have originally then transported over the public network by using propriety solutions. GFP offers two different mapping modes GFP-T & GFP-F. The ITU standard is G.7041. GFP-T GFP Transport GFP-T offers direct transmission of data streams regarding low latency, such as VoIP, digital video and SAN application. GFP-F GFP Framed GFP-T is normally used to encapsulate packet/ frame based protocols such as IP/PPP or Ethernet. The frame is entirely assembled before transmission through the SONET/SDH network. Figure given below is an example of how packet data can be

transported.


IP

Ethernet

SAN

HDLC

ATM POS

SDH

FC ESCON FICON

PDH

Packet data transfer

PPP

At present, most line interfaces for IP edge routers and most Frame Relay and PPP interfaces operate at POH rates or low order SDH/ SONET rates, although STM-16/0C-48 and STM-64/0C-192l in inter--faces are being introduced in big way, specially in MAN and WAN networks. Taken into account, the widespread availability of inexpensive 10/100/1000 Mbit/ s Ethernet interfaces on Customer Premises equipment (CPE), there is a strong interest for a QOS friendly, standard-based mechanism to transport IP, Ethernet and SAN traffic over TDM and WDM networks. Based on this interest, a mapping of all these Variable Bit Rate (VBR) signals into a Constant Bit Rate (CBR) signal was developed. This mapping is defined as Generic Frame Procedure (GFP). It offers significantly reduced latency and effective, improved bandwidth utilization.

Section-III

Chapter-1

Overview of

Mobile Communication & Cellular Concepts

E3E4 Mobile concepts, Ver2 28.02.2008 1 of 6

Mobile communications: Basic concepts

From ancient to modern times, mankind has been looking for means of long distance

communications. For centuries, letters proofed to be the most reliable way to transmit

information. Fire, flags, horns, etc. were used to transmit information faster. Technical

improvements in the 19th

century simplified long distance communications: Telegraphy,

and later on telephony. Both techniques were wireline. In 1873, J. C. Maxwell laid the

foundation of the electro-magnetic theory by summarising empirical results in four

equations, which are still valid today. It would however be several decades before

Marconi made economic use of this theory by developing devices for wireless

transmission of Morse signals (about 1895). Already 6 years later, the first transatlantic

wireless transmission of Morse signals took place. Voice was transmitted the first time in

1906 (R. Fesseden), and one of the first radio broadcast transmission 1909 in New York.

The economically most successful wireless application in the first half of the 20th

century was radio broadcast. There is one transmitter, the so-called radio station.

Information, such as news, music, etc. is transmitted from the radio station to the

receiver equipment, the radio device. This type of one-way transmission is called


simplex transmission. The transmission takes place only in one direction, from

the transmitter to the receiver.

The first commercial wireless car phone telephony service started in the late 1940

in St. Louise, Missouri (USA). It was a car phone service, because at that time,

the mobile phone equipment was bulky and heavy. Actually, in the start-up, it

filled the whole back of the car. But it was a real full duplex transmission

solution. In the 50ies, several vehicle radio systems were also installed in Europe.

These systems are nowadays called single cell systems. The user data

transmission takes place between the mobile phone and the base station (BS). A

base station transmits and receives user data. While a mobile phone is only

responsible for its user’s data transmission and reception, a base station is capable

to handle the calls of several subscribers simultaneously. The transmission of user

data from the base station to the mobile phone is called downlink (DL), the

transmission from the mobile phone to the base station uplink (UL) direction.

The area, where the wireless transmission between mobile phones and the base

station can take place, is the base stations supply area, called cell. For

conversation, a technical solution is required, where the information flow can take

place in two directions. This type of transmission is called duplex transmission.

Walky-talky was already available the early 30ies. This system already allowed a

transmission of user data in two directions, but there was a limitation: The users

were not allowed to transmit at the same time. In other words, you could only

receive or transmit user information. This type of transmission is therefore often

called semi-duplex transmission. For telephony services, a technical solutions is

required, where subscribers have the impression, that they can speak (transmit)

and hear (receive) simultaneously. This type of transmission solution is regarded

as full duplex transmission.


Single cell systems are quite limited. The more and more distant the subscriber is from

the base station, the lower the quality of the radio link. If the subscriber is leaving the

supply area of the cell, no communication is possible any more. In other words, the

mobile communication service was only available within the cell. In order to overcome

this limitation, cellular systems were introduced. A cellular mobile communication

system consists of several cells, which can overlap. By doing so, a whole geographical

area can be supported with the mobile communication service.

But what happens, when a subscriber moves during a call from one cell to another cell? It

would be very annoying, if the call is dropped. If the subscriber is leaving a cell, and in

parallel is entering a new cell, then the system makes new radio resources available in the


neighbouring cell, and then the call is handed over from on cell to the next one. By doing

so, service continuation is guaranteed, even when the subscriber is moving. The process

is called handover (HO).

A handover takes place during a call, i.e. when the mobile phone is in active (dedicated)

mode. A mobile phone can also be in idle mode. In this case, the mobile phone is

switched on, but no resources are allocated to it to allow user data transmission. In this

mode, the mobile phone is still listening to information, broadcasted by the base station.

Why? Imagine, there is a mobile terminated call. The mobile phone is then paged in the

cell. This means the phone receives information that there is a mobile terminated call. A

cellular system may consist of hundreds of cells. If the mobile network does not know, in

which cell the mobile phone is located, it must be paged in all of them. To reduce load on

networks, paging in is done in small parts of a mobile an operators network. Mobile

network operators group cells in administrative units called location areas (LA). A

mobile phone is paged in only one location area.

But how does the cellular system know, in which location area the mobile phone is

located? And how does the mobile phone know? In every cell, system information is

continuously transmitted. The system information includes the location area information.

In the idle mode, the mobile phone is listening to this system information. If the

subscriber moves hereby from one cell to the next cell, and the new cell belongs to the

same location area, the mobile stays idle. If the new cell belongs to a new location area,

then the mobile phone has to become active. It starts a communication with the network,

informing it about it new location. This is stored in databases within the mobile network,

and if there is a mobile terminated call, the network knows where to page the subscriber.


The process, where the mobile phone informs the network about its new location is called

Location Update Procedure (LUP).

With the introduction of cellular mobile communication systems, we

refer to generations. First generation prominent mobile communication systems were

• TACS (Total Access Communications System)

• NMT (Nordic Mobile Telephony)

• AMPS (Advanced Mobile Phone Service)

• C450

All of them were commercially launched in the 80s of the last century. The 1st

generation

mobile communication systems often offered national wide coverage. But there were

limitations: Most of them did not support roaming. Roaming is the ability to use an other

operator’s network infrastructure. International roaming is the ability to go even to

another country and use the local operator’s infrastructure.

Most 1st

generation mobile communication systems only supported

speech transmission, but not data transmission, such as fax. Supplementary services, such

as number indication and call forwarding, when busy. The transmission takes place

unprotected via the radio interface – as a consequence, eavesdropping is possible. Also

the radio interface was the main bottleneck in terms of capacity. Improved solutions were

urgently required. This led to the inauguration of the 2nd

generation mobile

communication systems, one of which is GSM.


GSM Frequency Bands

• GSM-900 uses 890–915 MHz to send information from the mobile station to the

base station (uplink) and 935–960 MHz for the other direction (downlink),

providing 124 RF channels (channel numbers 1 to 124) spaced at 200 kHz.

Duplex spacing of 45 MHz is used.

In some countries the GSM-900 band has been extended to cover a larger

frequency range. This 'extended GSM', E-GSM, uses 880–915 MHz (uplink) and

925–960 MHz (downlink), adding 50 channels to the original GSM-900 band.

The GSM specifications also describe 'railways GSM', GSM-R, which uses

876–915 MHz (uplink) and 921–960 MHz (downlink). GSM-R provides

additional channels and specialized services for use by railway personnel.

All these variants are included in the GSM-900 specification.

• GSM-1800 uses 1710–1785 MHz to send information from the mobile station to

the base tranceiver station (uplink) and 1805–1880 MHz for the other direction

(downlink), Duplex spacing is 95 MHz.

• GSM-850 uses 824–849 MHz to send information from the mobile station to the

base station (uplink) and 869–894 MHz for the other direction (downlink).

• GSM-1900 uses 1850–1910 MHz to send information from the mobile station to

the base station (uplink) and 1930–1990 MHz for the other direction (downlink).

GSM Handsets

Today, most telephones support multiple bands as used in different countries. These are

typically referred to as multi-band phones. Dual-band phones can cover GSM networks

in pairs such as 900 and 1800 MHz frequencies or 850 and 1900. European tri-band

phones typically cover the 900, 1800 and 1900 bands giving good coverage in Europe

and allowing limited use in North America, while North American tri-band phones utilize

850, 1800 and 1900 for wide-spread North American service but limited world-wide use.

A new addition has been the quad-band phone, supporting all four major GSM bands,

allowing for global use.

Section-III

Chapter-2

GSM Architecture

E3E4 GSM Architecture, Ver2 28.02.2008 1 of 5

GSM Introduction GSM (Global System for Mobile communications) is a 2nd Generation (2G), an open, digital cellular technology used for transmitting mobile voice and data services. GSM differs from first generation wireless systems in that it uses digital technology and time division multiple access transmission methods. GSM is a circuit-switched system that divides each 200kHz channel into eight 25kHz time-slots. GSM operates in the 900MHz and 1.8GHz bands in Europe and the 1.9GHz and 850MHz bands in the US. The 850MHz band is also used for GSM and 3GSM in Australia, Canada and many South American countries. GSM supports data transfer speeds of up to 9.6 kbit/s, allowing the transmission of basic data services such as SMS (Short Message Service). Another major benefit is its international roaming capability, allowing users to access the same services when travelling abroad as at home. This gives consumers seamless and same number connectivity in more than 210 countries. GSM satellite roaming has also extended service access to areas where terrestrial coverage is not available. GSM Architecture

Above figure shows the functional blocks at macro level. These are briefly explained in this handout.

MS


1.0 Mobile Station (MS) In GSM, the mobile phone is called Mobile Station (MS). The MS is a combination of terminal equipment and subscriber data. The terminal equipment as such is called ME (Mobile Equipment) and the subscriber's data is stored in a separate module called SIM (Subscriber Identity Module). Therefore, ME + SIM = MS. From the user’s point of view, the SIM is certainly the best-known database used in a GSM network. The SIM is a small memory device mounted on a card and contains user-specific identification. The SIM card can be taken out of one mobile equipment and inserted into another. In the GSM network, the SIM card identifies the user − just like a traveller uses a passport to identify himself. The SIM card contains the identification numbers of the user and a list of available networks. The SIM card also contains tools needed for authentication and ciphering. Depending on the type of the card, there is also storage space for messages, such as phone numbers. A home operator issues a SIM card when the user joins the network by making a service subscription. The home operator of the subscriber can be anywhere in the world, but for practical reasons the subscriber chooses one of the operators in the country where he/she spends most of the time. 2.0 Network Switching Subsystem (NSS) The Network Switching Subsystem (NSS) contains the network elements MSC, GMSC, VLR, HLR, AC and EIR.

The Network Switching Subsystem (NSS)


The main functions of NSS are:

• Call control: This identifies the subscriber, establishes a call, and clears the

connection after the conversation is over.

• Charging: This collects the charging information about a call (the numbers of the

caller and the called subscriber, the time and type of the transaction, etc.) and

transfers it to the Billing Centre.

• Mobility management: This maintains information about the subscriber's

location.

• Signalling: This applies to interfaces with the BSS and PSTN.

• Subscriber data handling: This is the permanent data storage in the HLR and

temporary storage of relevant data in the VLR.

2.1 Mobile services Switching Centre (MSC): The MSC is responsible for

controlling calls in the mobile network. It identifies the origin and destination of a call (mobile station or fixed telephone), as well as the type of a call. The MSC is responsible for several important tasks, such as the following.

• Call control: MSC identifies the type of call, the destination, and the origin of a call. It also sets up, supervises, and clears connections.

• Initiation of paging: Paging is the process of locating a particular mobile station in case of a mobile terminated call (a call to a mobile station).

2.2 Gateway Mobile services Switching Centre (GMSC): The GMSC is

responsible for the same tasks as the MSC, except for paging. It is needed in case of mobile terminated calls. In fixed networks, a call is established to the local exchange, to which the telephone is connected to. But in GSM, the MSC, which is serving the MS, changes with the subscriber’s mobility. Therefore, in a mobile terminated call, the call is set up to a well defined exchange in the subscriber’s home PLMN. This exchange is called GMSC. The GMSC than interacts with a database called Home Location Register, which holds the information about the MSC, which is currently serving the MS. The process of requesting location information from the HLR is called HLR Interrogation. Given the information about the serving MSC, the GMSC then continues the call establishment process. In many real life implementations, the MSC functionality and the GMSC functionality are implemented in the same equipment, which is then just called MSC. Many operators use GMSCs for breakout to external networks such as PSTNs.

2.3 Visitor Location Register (VLR): VLR is a database, which contains

information about subscribers currently being in the service area of the MSC/VLR, such as:

• Identification numbers of the subscribers

• Security information for authentication of the SIM card and for ciphering


The VLR carries out location registrations and updates. When a mobile station comes to a new MSC/VLR serving area, it must register itself in the VLR, in other words perform a location update. Please note that a mobile subscriber must always be registered in a VLR in order to use the services of the network. Also the mobile stations located in the own network is always registered in a VLR. The VLR database is temporary, in the sense that the data is held as long as the subscriber is within its service area. It also contains the address to every subscriber's Home Location Register, which is the next network element to be discussed.

2.4 Home Location Register (HLR): HLR maintains a permanent register of

the subscribers. For instance the subscriber identity numbers and the subscribed services can be found here. In addition to the fixed data, the HLR also keeps track of the current location of its customers. As you will see later, the GMSC asks for routing information from the HLR if a call is to be set up to a mobile station (mobile terminated call).

2.5 Authentication Centre (AC): The Authentication Centre provides security

information to the network, so that we can verify the SIM cards (authentication between the mobile station and the VLR, and cipher the information transmitted in the air interface (between the MS and the Base Transceiver Station)). The Authentication Centre supports the VLR's work by issuing so-called authentication triplets upon request.

2.6 Equipment Identity Register (EIR): As for AC, the Equipment Identity

Register is used for security reasons. But while the AC provides information for verifying the SIM cards, the EIR is responsible for IMEI checking (checking the validity of the mobile equipment). When this optional network element is in use, the mobile station is requested to provide the International Mobile Equipment Identity (IMEI) number. The EIR contains three lists:

• A mobile equipment in the white list is allowed to operate normally.

• If we suspect that a mobile equipment is faulty, we can monitor the use of it. It is then placed in the grey list.

• If the mobile equipment is reported stolen, or it is otherwise not allowed to operate in the network, it is placed in the black list.


3.0 Base Station Subsystem (BSS): The Base Station Subsystem is

responsible for managing the radio network, and it is controlled by an MSC. Typically, one MSC contains several BSSs. A BSS itself may cover a considerably large geographical area consisting of many cells (a cell refers to an area covered by one or more frequency resources). The BSS consists of the following elements:

• BSC Base Station Controller

• BTS Base Transceiver Station

• TRAU Transcoder and Rate Adaptation Unit (often referred to as TC (Transcoder))

Radio path control: In the GSM network, the Base Station Subsystem (BSS) is the part of the network taking care of radio resources, that is, radio channel allocation and quality of the radio connection. Synchronisation: The BSS uses hierarchical synchronisation, which means that the MSC synchronises the BSC, and the BSC further synchronises the BTSs associated with that particular BSC. Inside the BSS, synchronisation is controlled by the BSC. Synchronisation is a critical issue in the GSM network due to the nature of the information transferred. If the synchronisation chain is not working correctly, calls may be cut or the call quality may not be the best possible. Ultimately, it may even be impossible to establish a call. Air- and A-interface signalling: In order to establish a call, the MS must have a connection through the BSS. The BSS is located between two interfaces, the air- and the A-interface. The MS must have a connection through these two interfaces before a call can be established. Generally speaking, this connection may be either a signalling connection or a traffic (speech, data) connection. Mobility management and speech transcoding: BSS mobility management mainly covers the different cases of handovers.

Section-III

Chapter-3

Overview of GPRS & EDGE

E3E4 GPRS & Edge, Ver2 28.02.2008 1 of 6

Overview of GPRS GPRS (General Packet Radio Service) is the world's most ubiquitous wireless data service, available now with almost every GSM network. GSM system (2G) with GPRS capability is sometimes also known as 2.5G. GPRS is a connectivity solution based on Internet Protocols that supports a wide range of enterprise and consumer applications. Theoretical maximum speeds of up to 171.2 kilobits per second (kbps) are achievable with GPRS using all eight timeslots at the same time. This is about three times as fast as the data transmission speeds possible over today's fixed telecommunications networks and ten times as fast as current Circuit Switched Data services on GSM networks. Practically with throughput rates of up to 40 kbit/s, users have a similar access speed to a dial-up modem, but with the convenience of being able to connect from anywhere. GPRS customers enjoy advanced, feature-rich data services such as colour Internet browsing, e-mail on the move, powerful visual communications such as video streaming, multimedia messages and location-based services.

To use GPRS, users specifically need:

� a mobile phone or terminal that supports GPRS (existing GSM phone may NOT support GPRS);

� a subscription to a mobile telephone network that supports GPRS;

� Configuring mobile phone with the operator specific details. � Knowledge of how to configure handset is required. Many operators

provide configuration support through SMS.

� Knowledge of how to send and/or receive GPRS information using their specific model of mobile phone, including software and hardware

configuration � a destination to send or receive information through GPRS. Whereas

with SMS this was often another mobile phone, in the case of GPRS, it

is likely to be an Internet address, since GPRS is designed to make the Internet fully available to mobile users for the first time. From day

one, GPRS users can access any web page or other Internet applications- providing an immediate critical mass of uses;

GPRS standardization The ETSI (European Telecommunications Standardization Institute) does the standardisation work for GPRS.


Key points GPRS uses a packet-based switching technique, which will enhance GSM data services significantly, especially for bursty Internet/intranet traffic. Some application examples:

• Bus, train, airline real-time information

• Locating restaurants and other entertainment venues based on current Location

• Lottery

• E-commerce

• Banking

• E-mail

• Web browsing

The main advantages of GPRS for users:

• Instant access to data as if connected to an office LAN

• Charging based on amount of data transferred (not the time connected)

• Higher transmission speeds

The main advantages for operators:

• Fast network roll-out with minimum investment

• Excess voice capacity used for GPRS data

• Smooth path to 3G services

In circuit switching, each time a connection is required between two points, a link between the two points is established and the needed resources are reserved for the use of that single call for the complete duration of the call. In packet switching, the data to be transferred is divided up into packets, which are then sent through the network and re-assembled at the receiving end.


The GPRS network acts in parallel with the GSM network, providing packet switched connections to the external networks. The requirements of a GPRS network are the following:

• The GPRS network must use as much of the existing GSM infrastructure with the smallest number of modifications to it.

• Since a GPRS user may be on more than one data session, GPRS should be able to support one or more packet switched connections.

• To support the budgets of various GPRS users, it must be able to support different Quality of Service (QoS) subscriptions of the user.

• The GPRS network architecture has to be compatible with future 3rd and 4th generation mobile communication systems.

• It should be able to support both point-to-point and point-to-multipoint data connections.

• It should provide secure access to external networks.

Figure shows the architecture of a GPRS network. The GPRS system brings some new network elements to an existing GSM network. These elements are:

• Packet Control Unit (PCU)

• Serving GPRS Support Node (SGSN): the MSC of the GPRS network

• Gateway GPRS Support Node (GGSN): gateway to external networks

• Border Gateway (BG): a gateway to other PLMN

• Intra-PLMN backbone: an IP based network inter-connecting all the GPRS elements

• Charging Gateway (CG)

• Legal Interception Gateway (LIG)

• Domain Name System (DNS)


Firewalls: used wherever a connection to an external network is required. Not all of the network elements are compulsory for every GPRS network. Packet Control Unit (PCU) The PCU separates the circuit switched and packet switched traffic from the user and sends them to the GSM and GPRS networks respectively. It also performs most of the radio resource management functions of the GPRS network. The PCU can be either located in the BTS, BSC, or some other point between the MS and the MSC. There will be at least one PCU that serves a cell in which GPRS services will be available. Frame Relay technology is being used at present to interconnect the PCU to the GPRS core. Channel Codec Unit (CCU) The CCU is realised in the BTS to perform the Channel Coding (including the coding scheme algorithms), power control and timing advance procedures. Serving GPRS Support Node (SGSN) The SGSN is the most important element of the GPRS network. The SGSN of the GPRS network is equivalent to the MSC of the GSM network. There must at least one SGSN in a GPRS network. There is a coverage area associated with a SGSN. As the network expands and the number of subscribers increases, there may be more than one SGSN in a network. The SGSN has the following functions:

• Protocol conversion (for example IP to FR)

• Ciphering of GPRS data between the MS and SGSN

• Data compression is used to minimise the size of transmitted data units

• Authentication of GPRS users

• Mobility management as the subscriber moves from one area to another, and possibly one SGSN to another

• Routing of data to the relevant GGSN when a connection to an external network is required

• Interaction with the NSS (that is, MSC/VLR, HLR, EIR) via the SS7 network in order to retrieve subscription information

• Collection of charging data pertaining to the use of GPRS users

• Traffic statistics collections for network management purposes. Gateway GPRS Support Node (GGSN) The GGSN is the gateway to external networks. Every connection to a fixed external data etwork has to go through a GGSN. The GGSN acts as the anchor point in a GPRS data connection even when the subscriber moves to another SGSN during roaming. The GGSN may accept connection request from SGSN that is in another PLMN. Hence, the concept of coverage area does not apply to


GGSN. There are usually two or more GGSNs in a network for redundancy purposes, and they back up each other up in case of failure. The functions of a GGSN are given below:

• Routing mobile-destined packets coming from external networks to the relevant SGSN

• Routing packets originating from a mobile to the correct external network

• Interfaces to external IP networks and deals with security issues

• Collects charging data and traffic statistics

• Allocates dynamic or static IP addresses to mobiles either by itself or with the help of a DHCP or a RADIUS server

• Involved in the establishment of tunnels with the SGSN and with other external networks and VPN.

From the external network's point of view, the GGSN is simply a router to an IP sub-network. This is shown below. When the GGSN receives data addressed to a specific user in the mobile network, it first checks if the address is active. If it is, the GGSN forwards the data to the SGSN serving the mobile. If the address is inactive, the data is discarded. The GGSN also routes mobile originated packets to the correct external network. GPRS MS (Mobile Station/Handset) Different GPRS MS classes were introduced to cope with the different needs of future subscribers. The mobiles differ in their capabilities.


What is EDGE?

Further enhancements to GSM networks are provided by Enhanced Data rates for GSM Evolution (EDGE) technology. EDGE provides up to three times the data capacity of GPRS. Using EDGE, operators can handle three times more subscribers than GPRS; triple their data rate per subscriber, or add extra capacity to their voice communications. EDGE uses the same TDMA (Time Division Multiple Access) frame structure, logic channel and 200kHz carrier bandwidth as today's GSM networks, which allows it to be overlaid directly onto an existing GSM network. Some people classify the GSM network with EDGE capability as 2.75G. EDGE allows the delivery of advanced mobile services such as the downloading of video and music clips, full multimedia messaging, high-speed colour Internet access and e-mail on the move. Although EDGE requires no hardware or software changes to be made in GSM core networks, base stations must be modified. EDGE compatible transceiver units must be installed and the base station subsystem (BSS) needs to be upgraded to support EDGE. New mobile terminal hardware and software is also required to decode/encode the new modulation and coding schemes and carry the higher user data rates to implement new services. Due to the very small incremental cost of including EDGE capability in GSM network deployment, virtually all new GSM infrastructure deployments are also EDGE capable and nearly all new mid- to high-level GSM devices also include EDGE radio technology. The Global mobile Suppliers Association (GSA) states that, as of May 2007, there were 223 commercial GSM/EDGE networks in 113 countries, from a total of 287 mobile network operator commitments in 142 countries (source: www.gsacom.com).

Section-III

Chapter-4

GSM Services

E3E4 GSM services Ver2 28.02.2008 1 of 9

INTRODUCTION The primary objective of a mobile telephony system is to allow mobile subscribers to

communicate effectively. GSM systems provide this by offering a number of different

basic telecommunications services.

The service functionality of GSM system improves with each system release.

Technical specifications are continuously being developed in order to incorporate new

and improved functions into the system.

SERVICE CATEGORIES

There are two main types of telecommunications services:

• Basic services: These are available to all subscribers to a mobile network.

For example, the ability to make voice telephone calls is a basic service.

Basic telecommunication services can be divided into two main categories:

� Teleservices: A teleservice allows the subscriber to communicate

(usually via voice, fax, data or SMS) with another subscriber. It is a

complete system including necessary terminal equipment.

� Bearer services: A bearer service transports speech and data as digital

information within the network between user interfaces. A bearer

service is the capability to transfer information and does not include

the end-user equipment. Every teleservice is associated with a bearer

service. For example, a bearer service associated with the speech

telephony teleservice is the timeslot assigned to a call on a TDMA

frame over the air interface.

• Supplementary services: These are additional services that are available by

subscription only. Call forwarding is an example of a supplementary

service.

GSM systems are also designed to enable operators to differentiate their services from

their competitor’s services using a technique based on Mobile Intelligent Network

(MIN) solutions.

BASIC TELECOMMUNICATIONS SERVICES

1.0 BEARER SERVICES

GSM systems offer a wide range of bearer services. The DTI supports data

services offered by the system. Rates up to 48 kbits/s are possible.

1.1 Traffic to PSTN: for data traffic external to PLMN such as internetworking

with ISDN or directly to PSTN, the system selects a suitable modem in the DTI.


1.2 Traffic to ISDN: an entire set of data communication services with ISDN

terminals is available. Unrestricted digital information is transferred and no

modem is necessary.

1.3 Traffic to Packet Switched Public Data Network (PSPDN): Packet service

supports synchronous data transfers with the PSPDN with rates from 1.2 to 48

kbits/s. With synchronous data transfers a packet mode terminal can be directly

connected to the MS. Synchronous data communication between an MS and a

packet switched network is possible via the packet Assembler-Disassembler

(PAD) facility. Rates between 300 and 9600 bits/s are supported.

Figure 1 Data call in GSM to PSPDN

1.4 Traffic to Circuit Switched Public Data Network (CSPDN): Data

communications with a CSPDN is possible via the PSTN or ISDN, depending

on the CSPDN-transit network interface.

1.5 Traffic to Internet: traditionally, an MSC accessed Internet nodes via existing

networks such as the PSTN. However, the direct access function enables an

MSC to communicate directly with Internet nodes, thus reducing call set-up

time.

1.6 ISDN Primary Rate Access (PRA): this function enables an MSC to provide

PRA services to subscribers. For example, a network operator can offer PABX

connection services through the PLMN. In this way the operator can compete

directly with PSTN operators for ISDN business subscribers. PRA provides a

data rate of up to 2 Mbits/s.

MSC/VLR

PAD PST

N

PAD

PST

N

BSC IPNetwork PSPDN


2.0 TELESERVICES

This section describes the major teleservices supported by GSM systems.

2.1 Speech: This is normal telephony (two-way voice communication) with the

ability to make and receive calls to/from fixed and mobile subscribers

worldwide. This is the most fundamental service offered.

2.2 Emergency calls: The emergency call function enables a subscriber to make an

emergency call by pressing a predefined button or by using the emergency

number. With an emergency area origin identifier, the call is automatically

routed to the emergency center nearest to the subscriber. Emergency calls can

be made with the phone itself, without a valid SIM-card, overriding locked

phone and pin codes.

2.3 Facsimile group 3: GSM supports International

Telecommunications Union (ITU) group 3 facsimile. Standard fax machines

are designed to be connected to a telephone using analog signals, a special fax

converter is connected to the exchange. This enables a connected fax to

communicate with any analog fax in the fixed network.

2.4 Dual Tone Multi Frequency (DTMF): This is a tone signaling facility which

is often used for various control purposes, such as remote control of answering

machines and interacting with automated telephone services.

2.5 Alternative Speech/Fax: This service allows the subscriber to alternate

between speech and fax within one call setup. The subscriber can start the call

either with speech or fax and then alternate between the two call types. The

subscriber can switch several times within the same call.

2.6 Short Message Services (SMS): This service allows simple text messages

consisting of a maximum of 160 alphanumeric characters to be sent to or from

an MS.

If the MS is switched off, or has left the coverage area, the message is stored in

a Short Message Service Center (SMS-C). When the mobile is switched on

again or has re-entered the network coverage area, the subscriber is informed

that there is a message. This function guarantees that messages are delivered.

2.7 SMS Cell Broadcast (SMSCB): The cell broadcast facility is a variation of the

short message service. A text message with a maximum length of 93 characters

can be broadcast to all mobiles within a certain geographic area. Typical

applications are traffic congestion warnings and accident reports, and in the

future, possibly advertisements.


2.8 Voice mail: This service is an answering machine within the network that is

controlled by the subscriber. Calls can be forwarded to the subscriber’s voice

mailbox. The subscriber accesses the mailbox using a personal security code.

2.9 Fax mail: This service allows the subscriber to receive fax messages at any fax

machine via the MS. Fax messages are stored in a network service center. The

subscriber accesses the fax mail via a personal security code and the fax is then

sent to the desired fax number.

3.0 SUPPLEMENTARY SERVICES

This section describes the main supplementary services supported by GSM

systems.

3.1 Call forwarding: This service provides the subscriber with the ability to

forward incoming calls to another telephone number in the following situations:

• Call forwarding on MS not reachable

• Call forwarding on MS busy

• Call forwarding on no reply

• Call forwarding, unconditional

3.2 Barring of outgoing calls: The subscriber can activate or deactivate this service

from the MS with a variety of options for barring outgoing calls. For example,

the subscriber can:

• Bar all outgoing calls

• Bar all outgoing international calls

• Bar all outgoing international calls except those directed to

the home PLMN

3.3 Barring of incoming calls: With this function, the subscriber can prevent

incoming calls. This is desirable because in some cases the called mobile

subscriber is charged for parts of an incoming call (e.g. during international

roaming).

There are two incoming call barring options:

• Barring of all incoming calls

• Barring of incoming calls when outside home PLMN

3.4 Advice of Charge: The advice of Charge (AoC) service provides the MS with

information needed to calculate the charge of a call. This information is

provided at call set-up.

Charges are indicated for the call in progress when mobile originated. For a

mobile terminated call, AoC only offers information on the roaming leg.


3.5 Account Codes: This service enables a subscriber, e.g. a business, to identify

an account number, which is to be charged for particular call components.

Account codes can be identified on a per call basis.

3.6 Call waiting: This service notifies the mobile subscriber, usually by an audible

tone, for incoming call. The call can then be answered, rejected or ignored.

The incoming call can be any type of basic service including speech, data or

fax. There is no notification in the case of an emergency call or SMS.

3.7 Call hold: This supplementary service enables the subscriber to put the basic

normal telephony service on hold in order to set up a new call or accept a

waiting call. Communication with the original call can then be re-established.

3.8 Multiparty service: The multiparty service enables a mobile subscriber to

establish a multiparty conversation, that is, a simultaneous conversation

between up to six subscribers. This service can only be used with basic speech

telephony.

3.9 Calling line identification services: These supplementary services cover both the presentation and restriction of the

calling line identity. The presentation part of the service supplies the called

party with the ISDN or MSISDN number of the calling party. The restriction

service enables calling parties to restrict the presentation of their numbers on the

MSs of called parties. Restriction overrides presentation

3.10 Connected line identification presentation/restriction:

These supplementary services supply the calling party with the ISDN number

of the connected (called) party. The restriction enables the connected party to

restrict the presentation. Restriction overrides presentation. This service is

useful when the call is forwarded or when it is connected via a switchboard.

3.11 Closed User Group (CUG):

The CUG service enables subscribers connected to the PLMN/ISDN and

possibl0y other networks, to form groups in which access is restricted. For

example, members of a specific CUG can communicate with each other, but

generally not with users outside the group.


4.0 INNOVATIVE SERVICES

Innovative features offer a level of service beyond the basic network standards.

New features are developed on an ongoing basic as customer demands and

competition increase. Some features are described in this section.

Single personal number: The single personal number service allows a

subscriber to arrange call forwarding to other networks when the mobile is not

reached in the subscriber’s primary network. With this feature, one directory

number can reach the subscriber even though the subscriber may have

subscriptions in several different networks.

Dual numbering: This feature allows the subscriber to have two different

directory numbers connected to the same subscription and the same mobile

equipment. In this way different accounts can be connected to the different

directory numbers. For example, the subscriber may want one business account

and one private account connected to the same subscription. Support for this

feature is required in the MS.

Immediate call itemization: This feature is also called ‘Hot billing’. It is used

when it is necessary to have immediate call charging data output (e.g. to bill a

third party for use of a telephone, which is rented).

Regional call itemization: These features allow subscribers to subscribe

to a service in a specified geographical area. Requests for service outside the

area are rejected with the exception of emergency calls and SMS. For local

subscriptions, the geographical area consists of a number of cells, and for

regional subscriptions, the area consists of LAs. The cells or LAs do not need

to be adjacent but can be spread out over the PLMN. For regional

subscriptions, LAs in other PLMNs in other countries may be included.

Handovers are not influenced.

Geographically differentiated charging: This feature enables the GSM PLMN

area to be divided into different tariff regions. A tariff region is defined as a set

of cells. A subscriber may be offered cheaper calls within certain areas. This

feature can be combined with the service regional subscription.


5.0 LOCATION BASED SERVICES

A location Based service (LBS) can be described as an application that is

dependent on a certain location. Two broad categories of LBS can be defined as

triggered and user requested. In a user requested scenario, the user is retrieving

the position once and uses it on subsequent requests for location dependent

information. This type of service usually involves either personal location (i.e.

finding where you are) or service location (i.e. where is the nearest). Examples

of this type of LBS are navigation (usually involving a map) and direction

(routing information). A triggered LBS by contrast relies on a condition set up

in advance that, once fulfilled, retrieves the position of a given device. An

example is when the user passes across the boundaries of the cells in a mobile

network. Another example is in emergency center triggers an automatic location

request from the mobile network.

5.1 GSM Cellular Locations

Due to the cellular nature of the GSM mobile telephone network, it is possible

to determine the location of a regular GSM mobile telephone. The basic

system of cell ID, described below, is somewhat crude but techniques are

available to provide increased accuracy. This section describes one method of

increasing the accuracy of cell ID but others also exit. The advantage of

cellular positioning over GPS is that the signal is much stronger and therefore

will operate indoors; it is also unaffected by the urban canyon effect (subject to

GSM coverage).

5.1.1 Cell lD

Cell ID is the most basic form of cellular location and works simply by

detection the Base Transceiver Station (BTS) with which the telephone is

registered. At any moment in time, the mobile telephone/Station (MS) is

registered to a BTS. This is usually the nearest BTS but may occasionally be

the BTS of a neighbouring cell due to terrain, cell overlap or if the nearest

BTS is congested. Cells vary in size depending on terrain and the anticipated

number of users; hence in city centers cells are much smaller than in rural

location. This difference in cell size greatly affects the accuracy of a position

fix since the location reported is in fact the location of the BTS and the MS

may be anywhere within the boundary of the cell. Typically the extent of

error in urban locations may be around 500 metres but in rural locations this

can increase up to about 15 kms. Each base-station will have multiple

antennae, each covering a sector of the cell. So a BTS with there antennae

will produce a cell with there 1200 sectors. By detecting the antenna with

which the MS is registered, the location of the MS can be narrowed down to

somewhere within a sector of the cell with the BTS at its apex.


5.2 Applications

Service providers hope that location services will stimulate demand for

wireless data services. Location information may be used by an application

provider to personalize the service, or to improve the user interface by

reducing the need to interact with a small device while on the move. This

section aims to give a brief insight into a range of likely applications of

location based services.

5.2.1 Communication Some LBS applications with self-contained user device obtain a position

using one of the methods described above, perform some processing and then

present the resulting data back to the user. Many other applications will require

the position to be sent to a server either for display to other parties, processing

or referencing against additional content. Consumer applications will often use

SMS text messaging because it is simple to use and familiar to most mobile

users. The disadvantage of SMS is that it is limited to text-based data (although

the impending Multimedia Messaging Service (MMS) will allow still images,

audio and video to be transmitted). WAP may be considered as an alternative

communications channel that provides more data capacity and reduces the end-

to-end delay. SMS is also rather expensive as a data carrier and so may not be

cost effective for some applications where position reports need to be

transmitted at 5 minutes intervals though out the day, for example. GPRS may

be a more appropriate bearer for some applications as only the data transmitted

will be charged for and the high data rates would allow for large position and

telemetry logs to be downloaded at the end of the day if required. All of the

communications channels discussed so far have relied on the GSM network but

for safety critical applications or for tracking of devices in remote areas GSM

may not be appropriate. A satellite network, such as Inmarsat C or D+ may be

preferable if global coverage is required, although there will be an obvious trade

off with cost per position report and the hardware is likely to be more bulky and

demand more power.

5.2.2 Fleet Management The purpose of a fleet management application is to allow a company to keep

track of its mobile assets in near real time and to be able to use that information

not only to increase performance and utilization but also decrease operating

costs. As an example, consider the case of a delivery company. By having its

fleet of delivery vans reporting their position at regular intervals throughout the

day, if an urgent collection is required the company knows which is the nearest

van and can calculate the travel time required, therefore optimizing the

distribution of tasks. If the vehicle is also reporting telemetry data about engine

performance and driving habits (acceleration, breaking etc.) the company can

also detect mechanical problems before they cause damage and encourage their

drivers to adopt a more fuel efficient driving behavior. Geographic boundaries,

known as geofences, could be configured that trigger alerts when the object


being traced crosses the geofences perimeter. These could be defined so that

when the lorry arrives within 5 miles of the depot an alert is triggered to

forewarn the loading day crew of the van’s arrival. Location data could also be

viewed by customers to get information about the location of their deliveries

and expected delivery time.

5.2.3 Routing Navigation is another increasingly common implantation of location based

services and the benefits in terms of optimized routing, avoidance of traffic

congestion and early warning of diversions, accidents and road works are

easy to recognize. Apart from detailed turn-by-turn directions, there is

growing demand for ‘Where’s my nearest…? Type applications where an end

user requests the nearest business of a particular type relative to their current

location. For example, “Where’s my nearest Italian restaurant?” .To date,

there applications have relied on self positioning by the user where the user

has to define their location manually either by entering a street name, town

name, postcode or some other reference. This is because until now it has not

been possible for a third party application provider to determine roll-out of

APls to the network’s Cell ID data will provide a significant boost to these

services.

5.2.4 Safety and Security An emerging application of location-based services is in the area of workforce

safety. By equipping their workforce with a small electronic device that

enables location determination and transmission into a service center, a

company can monitor the condition of lone workers and those in high-risk

areas. Status updates may be requested at regular intervals and the device may

have a ‘panic button’ to allow the user to request for assistance to be

dispatched to their precise location in the event of an emergency. Vehicles can

now be equipped with covertly installed tracking devices to allow their safe

recovery in the event of theft. Many of these systems are so successful that

motor insurance companies now offer discounts to the insurance premiums of

those that choose to have the relevant devices installed.

5.2.5 Entertainment The limited availability of low-cost, mass market positioning devices has so

far been a barrier to location based services entering the entertainment arena

because they require specialized GPS hardware. However, the combination

of the ever-decreasing price of GPS technology and the imminent

availability of GSM Cell ID, positing has contributed to the appearance of

some innovative entertainment applications. Location-based directory

services are using either a WAP or SMS interfaces. Examples for this type

of applications are DJ requests, voting, competitions are dating services.

Many applications within the entertainment sector will be enhanced by the

MMS application.

Section-III

Chapter-5

Overview of CDMA Technology

E3E4 CDMA Overview, Ver1 14.12.2007 1 of 14

OVERVIEW OF CDMA

1. INTRODUCTION

Access Network, the network between local exchange and subscriber, in the Telecom

Network accounts for a major portion of resources both in terms of capital and manpower. So far,

the subscriber loop has remained in the domain of the copper cable providing cost effective

solution in the past. Quick deployment of subscriber loop, coverage of inaccessible and remote

locations coupled with modern technology have led to the emergence of new Access

Technologies. The various technological options available are as follows:

1. Multi Access Radio Relay

2. Wireless In Local Loop

3. Fibre In the Local Loop

2. WIRELESS IN LOCAL LOOP (WILL).

Fixed Wireless telephony in the subscriber access network also known as Wireless in

Local Loop (WILL) is one of the hottest emerging market segments in global

telecommunications today. WILL is generally used as “the last mile solution” to deliver basic

phone service expeditiously where none has existed before. Flexibility and expediency are

becoming the key driving factors behind the deployment of WILL.

Different technologies have been developed by the different countries, like, CT2 from

France, PHS from Japan, DECT from Europe, and DAMPS & CDMA from USA. Let us

discuss CDMA technology in WILL application as it has a potential ability to tolerate a fair

amount of interference as compared to other conventional radios. This leads to a considerable

advantage from a system point of view.

3. SPREAD SPECTRUM PRINCIPLE

Originally Spread spectrum radio technology was developed for military use to counter the

interference by hostile jamming. The broad spectrum of the transmitted signal gives rise to

“Spread Spectrum”. A Spread Spectrum signal is generated by modulating the radio frequency

(RF) signal with a code consisting of different pseudo random binary sequences, which is

inherently resistant to noisy signal environment.

A number of Spread spectrum RF signals thus generated share the same frequency spectrum

and thus the entire bandwidth available in the band is used by each of the users using same

frequency at the same time.

On the receive side only the signal energy with the selected binary sequence code is accepted

and original information content (data) is recovered. The other users signals, whose codes do not

match contribute only to the noise and are not “de-spread” back in bandwidth (Figure-I).This

transmission and reception of signals differentiated by “codes” using the same frequency

simultaneously by a number of users is known as Code Division Multiple Access (CDMA)

Technique as opposed to conventional method of Frequency Division Multiple Access and Time

Division Multiple Access.


1.25MHz 1.25MHz

10KHz

CDMA ACCESS -A CONCEPT

Wideband Spectrum

Transmitted

• Other CELL

Interference

•Other Users Noise

10KHz

DATA

(9.6Kbp)ENCODING

CARRIER

PN

SOURCE

DATADECODER

CARRIER

FILTER

1.25MHz 1.25MHz

PN

SOURCE

•Background Noise

Wideband Spectrum

Received

“Despread” original

data&other noiseDATA to be transmitted

•External

interference

Figure-1

In figure -1 it has been tried to explain that how the base band signal of 9.6 Kbps is spread using

a Pseudo-random Noise(PN) source to occupy entire bandwidth of 1.25 Mhz. At the receiving

end this signal will have interference from signals of other users of the same cell, users of

different cells and interference from other noise sources. All these signals get combined with the

desired signal but using a correct PN code the original data can be reproduced back. CDMA

channel in the trans and receive direction is a FDD (Frequency Division Duplexing) channel. The

salient features of a typical CDMA system are as follows:

• Frequency of operation: 824-849 Mhz and 869-894 Mhz

• Duplexing Method: Frequency Division Duplexing (FDD)

• Access Channel per carrier: Maximum 61Channels

• RF Spacing: 1.25 Mhz

• Coverage: 5 Km with hand held telephones and approx. 20 Km

with fixed units.

The different types of codes used for identification of traffic channels and users identification etc.

are as follows:

4. DIFFERENT CODES

4.1. Walsh Code: In CDMA the forward traffic channels are separated by unique “Walsh” code.

All such codes are orthogonal to each other. The individual subscriber can start communication

using one of these codes. These codes are traffic channel codes and are used for orthogonal

spreading of the information in the entire bandwidth. Orthogonality provides nearly perfect

isolation between the multiple signals transmitted by the base station


The basic concept behind creation of the code is as follows:

(a) Repeat the function right

(b) Repeat the function below

(c) Invert the function diagonally

Seed 0 0 0 0 0 0 0

0 1 0 1 0 1

0 0 1 1

0 1 1 0

4.2. Long Code: The long pseudo random noise (PN) sequence is based on 242

characteristic

polynomial. Reverse traffic channels (Mobile to Base) are separated by this long code and the

data in the forward direction (Base to Mobile) is scrambled. The PN codes are generated using

linear shift registers. The long code is unique for the subscribers and is known as users address

mask. It repeats every 41 days (at a clock rate of 1.2288 Mcps)

PN offset (Masking)

- Masking will cause the generator to produce the same sequence but offset in time.

- Masking provides the shift in time for PN codes.

- Different masks correspond to different time shifts.

- ESN are used as masks for users on the traffic channels.

4.3. Short Code: The short pseudo random noise (PN) sequence is based on 215

characteristic

polynomial. This short code differentiates the cells & the sectors in a cell. It also consists of

codes for I & Q channel feeding the modulator. Each cell uses different PN offsets. It repeats

every 26.67 msec (at a clock rate of 1.2288 Mcps)

5.0 CDMA Channels Forward Link Channels

Pilot Channel

Sync Channel

Paging Channels

Traffic Channels

Reverse Link Channels

Access Channels

Traffic Channels

Pilot channel (W0)

The pilot is used by the subs unit to obtain initial system synchronization and to distinguish cell

sites. Every sector of every cell site has a unique pilot channel.

• Transmitted constantly.

• Allows the mobile to acquire the system.

• Provides mobile with signal strength comparison.

• Approximately 20% of the radiated power is in the pilot.

• Has unique PN Offset for each cell or sector.


Sync channel (W32)

Used during system Acquisition stage. Sync channel provides the subscriber unit with network

information related to cell site identification, pilot transmit power & cell site PN offset.

• Used by mobile to synchronize with the system

• Transmits sync message with

- Pilot PN offset - System time

- Long PN code - System ID

- Network ID - Paging channel data rate

• Tx at 1200 bps

PAGING CHLS (W1-W7)

On this channel base station can page the subs unit and it can send call set-up and traffic

channel assignment information.

• Means of communication between base to mobile station.

• Paging CHL data Rates can be 2.4,4.8 or 9.6 Kbps.

• CDMA assignment has 7 paging channel.

• Each paging CHL supports 180 pages per second.

• Total pages/ CDMA RF channel = 1260

• Provides mobile with

• - System Parameter message - Neighbour list

• - Access Parameter list - CDMA Channel list

• Used by base station to :

• - Page mobile - Transmit overhead information

• - Assign mobile to traffic channel

Traffic Channels (W8-W31 & W33-W63)

The traffic channel carries the actual call. That is, the voice and control information between

the subs unit & base station.

TX up to 9.6kbps on rate set 1 and up to 14.4kbps on rate set 2.

Access Channel.

(a) Provides communication from Mobile to base station when mobile is not using traffic

Channel. The access channel is used for call origination & for response to pages, orders &

registration requests. It is paired with corresponding paging channel.

(b) Each Access CHL use long PN code.

(c) Base station responds to transmission on a particular Access Channel.

(d) Mobile responds to base station message by emitting on Access Channel.

(e) Transmits at 4800bps.


It is clear from the figure that in the forward direction both the rate sets are supported and the

data rate after convolution encoding will be 19.2 Ksps. Then using the PN code the signal is

scrambled. In which each symbol coming out of block interleaver is exclusively-ORed with one

symbol of scrambling sequence. Power control bits are then punctured at appropriate places.

Then this signal is orthogonally spread using one of the walsh codes. At this place the data rate

increases to 1.2288 Mcps, which is sent on I & Q channel. All the information is sent on both the

quadrature channels and the each quadrature is spread using short PN code. These short PN

codes are second layer of coding used to isolate one sector from another. Now this signal is

transmitted which will be received and demodulated at the mobile end.

Rake receiver CDMA mobiles use rake receivers. The rake receiver essentially a set of four or more receivers

(or fingers). One of the receivers constantly searches for different multipaths and helps to direct

the other three fingers to lock onto strong multipath signals.

• Allows combined reception of up to three different paths.

• Provides searcher receiver to identify changes in path characteristics/new cells.

• Provides both path diversity and frequency diversity.

Forward Traffic Channel Generation

9600 bps

4800 bps

2400 bps

1200 bps

Rate set 1

I PN

Convolutional

Encoder &

Repetition

Block

interleaver

Long

Code PN

decimator decimator

User

Address

Mask

(ESN)

O PN

Power

Control

bit

19.2 ksps

1.2288

19.2

ksps

R=1/2

Mcps

800bps

Rate set 2

14400 bps

7200 bps

3600 bps

1800 bps

R=3/4

Wt

1.2288

Mcps

64:1 24:1


In this process also both the rate sets are supported. After convolutional encoding the rates will

be 28.8 Ksps. In this case orthogonal modulation is followed by a data burst randomizer that

determines when to turn off the mobile transmitter to reduce average transmit power. In order to

Reverse Traffic Channel Generation

9600 bps

4800 bps

2400 bps

1200 bps

Rate set 1

I PN

Convolutional

Encoder &

Block

interleav

Long

Code PN

User

Address

Mask

(ESN)

O PN

28.8 ksps

1.2288

19.2

ksps

R=1/3

Mcps

Rate set 2

14400 bps

7200 bps

3600 bps

1800 bps

R=1/2

1.2288

Mcps Data

Burst

Rand.

Orthogonal

Modulation

307.2

KHz

Correlator 1

Correlator 2

Correlator 3

Searcher Correlator

C

O

M

B

I

N

E

R

CDMA mobile rake receiver


take advantage of reduced speech activity the vocoder reduces its data rate allowing the

transmission of the signal at a lower average level of power. The mobile uses full rates when it

transmits, but when redundant information is produced by symbol repetition scheme the data

burst randomizer turns off the transmitter pseudo randomly reducing the average transmission

power. Then the signal is direct sequence spread using long code and occupies the entire

bandwidth. The signal is then sent on I and Q channels and short PN codes are used for spreading

the signal, the quadrature branch is delayed by ½ bit to produce OQPSK modulation.Which is

sent to base station for reception and demodulation.

5. ADVANTAGES :

CDMA wireless access provides the following unique advantages:

5.1. Larger Capacity: Let us discuss this issue with the help of Shannon’s Theorem. It states

that the channel capacity is related to product of available band width and S/N ratio.

C = W log2 (1+S/N)

Where C = channel capacity

W = Band width available

S/N = Signal to noise ratio

It is clear that even if we improve S/N to a great extent the advantage that we are expected to get

in terms of channel capacity will not be proportionally increased. But instead if we increase the

bandwidth (W), we can achieve more channel capacity even at a lower S/N. That forms the basis

of CDMA approach, wherein increased channel capacity is obtained by increasing both W &

S/N. The S/N can be increased by devising proper power control methods.

5.1.1 Vocoder and variable data rates: As the telephone quality speech is band limited to 4

Khz, when it is digitized with PCM its bit rate rises to 64 Kb/s. Vocoding compress it to a lower

bit rate to reduce bandwidth. The transmitting vocoder takes voice samples and generates an

encoded speech/packet for transmission to the receiving vocoder. The receiving vocoder decodes

the received speech packet into voice samples. One of the important features of the variable rate

vocoder is the use of adaptive threshold to determine the required data rate. Vocoders are

variable rate vocoders. By operating the vocoder at half rate on some of the frames the capacity

of the system can be enhanced without noticeable degradation in the quality of the speech. This

phenomenon helps to absorb the occasional heavy requirement of traffic apart from suppression

of background noise. Thus the capacity advantage makes spread spectrum an ideal choice for use

in areas where the frequency spectrum is congested.

5.2. Less (Optimum) Power per cell:

Power Control Methods: As we have already seen that in CDMA the entire bandwidth

of 1.25 MHz, is used by all the subscribers served in that area. Hence they all will be transmitting

on the same frequency using the entire bandwidth but separated by different codes. At the

receiving end the noise contributed by all the subscribers is added up. To minimize the level of

interfering signals in CDMA, very powerful power control methods have been devised and are

listed below:


1. Reverse link open loop power control

2. Reverse link closed loop power control

3. Forward link power control

The objective of open loop power control in the reverse link (Mobile to Base) is that

the mobile station should adjust its transmit power according to the changes in its received power

from the base. Open loop power control attempts to ensure that the received signal strength at the

base station from different mobile stations, irrespective of their distances from the base station,

should be same.

In Closed loop power control in reverse link, the base station provides rapid corrections

to the mobile stations’ open loop estimates to maintain optimum transmit power by the mobile

stations. The base station measures the received signal strength from the mobile connected to it

and compares it with a threshold value and a decision is taken by the base every 1.25ms to either

increase or decrease the power of the mobile.

In forward link power control (Base to Mobile) the cell(base) adjusts its power in the

forward link for each subscriber, in response to measurements provided by the mobile station so

as to provide more power to the mobile who is relatively far away from the base or is in a

location experiencing more difficult environment.

These power control methods attempt to have an environment which permits high quality

communication (good S/N) and at the same time the interference to other mobile stations sharing

the same CDMA channel is minimum. Thus more numbers of mobile stations are able to use the

system without degradation in the performance. Apart from the capacity advantage thus gained,

power control extends the life of the battery used in portables and minimizes the concern of ill

effects of RF radiation on the human body.

5.3. Seamless Hand-off: CDMA provides soft hand-off feature for the mobile crossing from one

cell to another cell by combining the signals from both the cells in the transition areas. This

improves the performance of the network at the boundaries of the cells, virtually eliminating the

dropped calls.

5.4. No Frequency Planning: A CDMA system requires no frequency planning as the adjacent

cells use the same common frequency. A typical cellular system with a repetition rate of 7 and a

CDMA system is shown in the following figures which clearly indicates that in a CDMA

network no frequency planning is required.


FFFF

FFFF

FFFF

FFFF

FFFF

FFFF

FFFF

C D M A Frequency Reuse

F 7

F 6

F 2

F 1

F 5

F 3 A

F 4 F 1

F r e q u e n c e y R e u s e o f 7

5.5. High Tolerance to Interference: The primary advantage of spread spectrum is its ability to

tolerate a fair amount of interfering signals as compared to other conventional systems. This

factor provides a considerable advantage from a system point of view.

5.6. Multiple Diversity: Diversity techniques are often employed to counter the effect of fading.

The greater the number of diversity techniques employed, the better the performance of the

system in a difficult propagation environment.

CDMA has a vastly improved performance as it employs all the three diversity techniques in the

form of the following:

A. Frequency Diversity: A wide band RF signal of 1.25 Mhz being used.

B. Space Diversity: Employed by way of multipath rake receiver.

C. Time Diversity: Employed by way of symbol interleaving, error detection

and correction coding.

6. CAPACITY CONSIDERATIONS

Let us discuss a typical CDMA wireless in local loop system consisting of a single base

station located at the telephone exchange itself, serving a single “cell”. In order to increase the


number of subscribers served the cell is further divided into “sectors”. These sectors are served

by directional antennas.

CDMA Capacity

W/R 1 1

N= -------*-----*--------*n *g

Eb/Io d 1+f

Where

N= calls per sector

W= Spread spectrum Bandwidth (1.25 MHz)

R= data rate (9.6 kbps or 14.4 kbps)

Eb/Io= Bit energy/ other user interference density (7dB)

d= Voice activity factor (0.4)

f= other interference/ same interference (0.6)

n= loading factor (0.8)

g= reduction for variable power (0.85)

N= 27 users per sector for R=9.6Kbps

18 users per sector for R=14.4Kbps

Evolution of CDMA Networks

First deployment of CDMA in commercial cellular systems was in 1994-95 only with IS-95 A as

air-interface standard and IS-41 in core network; the complete network known as cdmaOne. Next

evolutionary step was use of IS-95B air interface standard which supported maximum data rate

up-to 64 kbps to a user. Further in CDMA 2000 1x version many of the limitations of earlier IS-

Data only 2.4 Mbps

RF backward compatible

Voice, 14.4k Voice, 64k

Voice, 9.6k Data only 10-60k

Voice, 128k/384k

GSM (Europe)

CDMA

CDMA2000 1x IS-95A

GPRS

EDGE

WCDMA

CDMA2000 1xEV-DO

IS-95B


95 standard were overcome and new features were added. As a result CDMA 2000 1x has a

higher voice capacity and better handling of packet data services.

Salient Features of CDMA 2000 1x

• Backward Compatibility with IS-95A & IS-95B

• Support for High data rates on same 1x Carrier

• Support for Simple IP and Mobile IP functionality for seamless mobility for data services.

• Higher capacity for voice communication

• Increased battery life

• Faster forward Power control (relative to IS-95)

• New Radio Configuration to support high data rates and more voice capacity.

Architecture of CDMA 2000 1x Network:

CDMA 2000 1x Network Architecture is divided in to three parts.

• CS-CN (Circuit Switched Core Network)

• PS-CN (Packet Switched Core Network)

• RAN (Radio Access Network)


Circuit Switched Core Network: This section is dedicated for voice communication and also

for wireless authentication. This section includes four parts

MSC (Mobile Switching Center)

HLR (Home Location Register)

VLR (Visitor Location Register)

AUC (Authentication Center)

MSC (Mobile Switching Center): It is responsible for setting up, managing and clearing

connections as well as routing the calls to the proper user & provides the network interfaces, the

charging function and the function of processing the signaling. MSC get data for call handling

from 3 databases: VLR/HLR/AUC.

HLR (Home Location Register): It is a static database. When a user applies for mobile service,

all data about this subscriber will be stored in HLR. It have information of a subscriber like ESN,

MDN, IMSI, MIN, service information and valid term. It also stores the mobile subscriber

location (MSC/VLR address), to set up the call.

VLR (Visitor Location Register): VLR is a dynamic database used by MSC for information

index. It stores all related information of mobile subscribers that enter its coverage area, which

enables MSC to set up incoming and outgoing calls. It stores the subscriber parameters which

includes subscriber number, location area identity (LAI), user’s status, services which subscriber

can use and so on. When the subscriber leaves this area, it should register in another VLR, and

the previous VLR will delete all the data about this subscriber. VLR can be built together with

the MSC or set separately.

AUC (Authentication Center): It is an entity to prevent illegal subscribers from accessing

CDMA network. It can generate the parameter to confirm the subscriber’s identity. At the same

time it can encrypt user’s data according to user’s request. AUC can be built separately or

together with HLR

Packet Switched Core Network: To provide better connectivity to the internet a new core

network i.e. PS-CN is introduced to the CDMA 2000 1x network. This section includes four

parts

PDSN (Packet Data Serving Node)

AAA Server

Home Agent/ Foreign Agent Server

PDSN (Packet Data Serving Node): Packet Data Serving Node (PDSN) provides the function

of routing of data between Radio Access Network (RAN) and internet.

AAA Server: PS-CN also has the responsibility to authenticate, authorise and account for the

CDMA 2000 subscribers wishing to obtain packet data services & to fulfil these task PDSN

requires support of AAA server.

Authenticate: verifying that the user is valid & allowed to use packet data services.


Authorization: subscription to the service being offered is valid.

Accounting: Accounting for the service used.

Home Agent/ Foreign Agent Server: HA & FA server is used when mobile IP services are

supported by CDMA 2000 PDSN. HA can be considered analogous to HLR and FA with VLR.

RAN (Radio Access Network): As in IS-95 RAN is composed of number of BSCs & BTSs

The CDMA 2000 1x RAN is enhanced to support a higher no. of users on air interface or in other

words it has a better spectral efficiency relative to IS-95. It is also modified to support the new

packet data services on same 1.25 Mhz channel. This is achieved by software up-gradation at

BTS and BSC and addition of a new hardware unit called Packet Control Function (PCF) at

BSC. The CDMA 2000 1x air interface is very different from IS-95 but still maintains the

backward compatibility with IS-95.

CDMA 2000 1x EV-DO:

Although IS-2000 is already capable of meeting the 3G data rate requirement of 2 Mbps (By

using 3x option) Qualcomm proposed a new standard 1xEV-DO (1x Evolution for Data

Optimized) in March of 2000 as another option that supports high-rate data services.

EVDO is optimized for delivering high speed IP wireless data to many mobile and stationary

terminals running multiple applications. EVDO is designed for an always on user experience.

In a classical CDMA 2000 system base station controls its power by using the power control

algorithms to provide the mobile a constant data rate and a quality of service for voice

applications

Power

Data Rate

But in EV-DO networks the base station transmits at a fixed power at all the times and controls

the rate of data transmission given a constant transmit power.

Power

Data Rate

Distance from the Base Station

Mobile Received Power P

o

w

e

r

Distance from the Base Station


Since EV-DO is specially designed for packet data services therefore EV-DO designs its air

interface to takes advantage of the characteristics of some data services, which are

Data rates are mostly asymmetrical: Data rate requirements downstream (on the forward link)

are usually higher than those upstream (on the reverse link).

Latency can be tolerated: Data services, unlike voice services, can withstand delays of up to

seconds.

Transmissions are bursty in nature: A burst of data transmission is often followed by a period

of inactivity.

Salient features of EV-DO

• EV-DO uses both CDMA and TDMA.

• Uses its own dedicated 1.25 Mhz carrier.

• It can support a maximum data rate of 2.4 Mbps in forward link.

• It can support a maximum data rate of 153.6 Mbps in reverse link.

• No power control on forward link is required.

• RF system components may be shared with 1xRTT.

Section-IV

Chapter-1

Broadband Wire line & Wireless Access Technologies

E3E4 Broadband Wireline & Wireless, Ver2 28.02.2008 1 of 12

Broadband Wire line Access Technologies

Introduction:

There is always increasing demand for higher capacity systems and more bandwidth for new generation, hence new various types of access technologies for broadband have to be found for this exponential growth. Broadband service commonly is high-speed Internet related services more than 256 kbps to several mbps. There are many different broadband technologies both wired and wireless. This article describes various types of broadband access technologies and BSNL’s access network of broadband.

High-speed Internet access (sometimes loosely referred to as “broadband internet access” or simply “broadband”) allows users to access the Internet and internet-related services at significantly higher speeds than traditional modems. High-speed Internet access makes the data processing capabilities necessary to use the Internet available via several devices or high-speed transmission technologies.

Learning Objective:

At the end of this topic you will be able to know- . a) What is broadband? Type of Internet services. b) Advantages of Broadband. Multiple Broadband Technologies. c) How Does Broadband Work. d) Digital Subscriber Line (DSL), DSLAM, Symmetrical Digital Subscriber Line

(SDSL), Asymmetrical Digital Subscriber Line (ADSL), ISDN Digital Subscriber Line (IDSL). DSL compared to ISDN.

e) BSNL’S Broadband Access Technology and Objectives. f) Differences between DSL and CM Service. g) Getting DSL or CM service and Installation at the premises of customer.

1.0 Narrowband Service category:

• Dial up Internet Service (PSTN + ISDN)

• Direct Internet Access Service (DIAS)

• CLI based Account less Internet Service

• Internet Leased Line Service

1.1 What is Broadband? As per TRAI: Broadband is an “An always-on data connection that is able to support interactive services and has the capability of minimum download speed of 256 kbps” Note: This definition for throughput may undergo upward changes in the future.


1.2 Advantages of Broadband • Always on (Not on shared media)

• Fast (speed ranging from 256 kbps to 2 Mbps)

• No disconnection

• No additional access charge

• Telephone and Data simultaneously

• Fat pipe has to be continuously supplemented with value added applications to enjoy the advantage.

1.3 Multiple Broadband Technologies There are many different types of broadband access technologies, such as cable, DSL, power line, satellite and wireless. Each of these technologies can compete to provide similar services to consumers and businesses.

• Digital Subscriber Line (DSL)

• Cable Modem (CM)

• Wireless Access WIMAX and WIFI

• Satellite Access

• Fiber technology

• Power Line Broadband There are many advantages of high-speed Internet access:

• The connection is always on, which means users can access the Internet without the need to dial up Internet service provider over a telephone line.

• Information can be download into your computer at significantly higher speeds than traditional modem.

• Users can go online without tying up their telephone lines.

• Business can use broadband networks for videoconferencing, and to let employees telecommute.

• Users can tap into an expand number of entertainment resources.

• An ‘ always-on’ data connection that is able to support interactive services including Internet access and has the capability of the minimum download speed of 256 kbps to an individual subscriber from the Point of presence (POP) of the service provider intending to provide Broadband service where multiple such individual Broadband connections are aggregated and the subscriber is able to access these interactive services including the internet through this POP. The interactive services will exclude any services for which a separate license is specifically required, for example, real-time voice transmission, except to the extent that it is presently permitted under ISP license with Internet Telephony.

1.4 How Does Broadband Work? High speed Internet access makes the data processing capabilities necessary to use the Internet available via one of several high-speed transmission technologies. These data processing capabilities are “digital” in nature, meaning that they compress vast amounts of voice, video and data information that are broken down into what are called “bts”. These bits become words, pictures, etc. on our computer screens. The transmission technologies that make high speed Internet access possible move these bits much more quickly than do traditional telephone or wireless connections.


2.0 Digital Subscriber Line (DSL) • Digital Subscriber line (DSL) is a wireline transmission technology that brings

data and information faster over copper telephone lines already installed in homes and business. Traditional phone service connects your home or business to a telephone company office via copper wires. A DSL modem accesses the local telephone company’s central office where a DSL Access DSLAM then transmits the signal from the copper telephone line onto a network backbone, and eventually to the Internet. With high-speed Internet access that uses DSL transmission technology, there is no need to “dial in” to a traditional modem. This service allows consumers and business to have an “always-on” dedicated connection to the Internet.

2.1 DSLAM

• DSLAM is the equipment located at a phone company’s central office (CO) that links many customer DSL connections over exiting copper telephone lines to a single high-speed ATM line. When the phone company receives a DSL signal, an ADSL modem with a POTS splitter detects voice calls and data. The DSLAM intermixes voice-frequency signals and high-speed DSL data traffic into a customer’s DSL line. It also separates incoming phone and data signals and directs them onto the appropriate carrier’s network. Voice calls are sent to the PSTN, and data are sent to the DSLAM, where it passes through the ATM to the Internet, then back through the DSLAM and ADSL modem before returning to the customer’s PC. More DSLAM channels a phone company has the more customers it can support. The DSLAM is the cornerstone of the DSL system and routes traffic to and from the customer via a business or home telephone line to provide high-speed DSL access to multimedia services such a Internet, fast data transfer, video conferencing, pay –per-view TV or video-on-demand and broadcast video. There are more than 40 million copper loops in the country available with BSNL and MTNL out of which 14 millions loops are in rural areas. Copper cable network of these operators is a combination of old and new cables and this makes provisioning of Broadband on the entire available copper loop technically unfit. Therefore around 25 to 30% of the remaining 26 million loops i.e. approximately 7 million loops can be leveraged for broadband service by BSNL and MNTL taking into account the condition/ life of copper cable and demand potential. Management of BSNL and MTNL has decided to provide 1.5 million connections by the end of 2005. The estimated growth for Broadband and internet subscribers in the country envisaged through various technologies is as follows. Year Ending Internet Subscribers Broadband Subscribers 2005 6 million 3 million 2007 18 million 9 million 2010 40 million 20 million


The following are types of DSL transmission technologies that may be used to provide high-speed Internet access:

• Symmetrical Digital Subscriber Line (SDSL): It is used typically for business applications such as video conferencing. The traffic from the user to the network is upstream traffic, and from the network to the user is downstream traffic. When the data rate in both directions is equal, it is called a symmetric service.

• Asymmetrical Digital Subscriber Line (ADSL): It is used primarily by residential users who receive a lot do data but do not send much, such as Internet surfers. ADSL provides faster speed in a downstream direction (from the telephone central office to the customer’s premises) than upstream (from customer’s premise to the telephone central office). When the upstream data rate is lower than the downstream rate, it is called an asymmetric service.

• Isdn Digital Subscriber Line (IDSL): It provides symmetrical connection with Integrated Services Digital Network (ISDN), and is designed to extend DSL to locations with a long distance to a telephone central office.

• High-data-rate Digital Subscriber Line (HDSL): it provides fixed symmetrical high-speed access at T1 rate (1.5 mbps), and is designed for business purposes.

• Very high-data-rate Digital Subscriber Line (VDSL): it provides both symmetrical and asymmetrical access with very high bit rate over the copper line. Deployment is very limited at this time.

2.2 DSL Compared to ISDN ISDN is an affordable way to have rapid access to the Internet. It is digital technology that is widely available and is an option for business located in areas not yet served by DSL. DSL and ISDN are different transmission technologies, yet both offer many of the same higher speed benefits to consumers. DSL offers potentially higher transmission speeds as well as a choice of connection speeds. ISDN is presently more widely available than DSL. DSL is an always-on service while ISDN requires dialing into a service provider’s network. If DSL transmission technology is not available in your area, ISDN may serve as an acceptable substitute for use in providing high-speed Internet access.

3.0 BSNL’S Broadband Access Technology BSNL has commissioned broadband, a world class, multi-gigabit, multi-protocol,

convergent IP infrastructure through National Internet Backbone II (NIB-II), that will provide convergent services through the same backbone and broadband access network. The Broadband service will be available on DSL technology (on the same copper cable that is used for connecting telephone). On a countrywide basis spanning 198 cities.

With the NIB-II project, BSNL has planned to roll Broadband services in a big way across the country. However, with the current plans under the NIB-II project, BSNL will still be in a position to become the number one player in the segment in the country with its nation-wide rollout. Broadband Services proposed to be rolled out include the following:


High Speed Internet Access 1. 1 mbps Upstream 2. 8 mbps Downstream 3. Video Streaming 4. Video-on-Demand 5. Video Conferencing 6. Interactive Gaming 7. Point-to-Point Data Network on IP

3.1 BSNL’s Objectives BSNL has undertaken this project with the following objectives:

• To utilize to the maximum BSNL’s exiting infrastructure � 40 million BSNL customers on CU � Large scale deployed Fibres in Access & core network � Deployed DLC system on Fibre.

• To increase the footprint across the country to provide Access Country-wide.

• To provide Value Added Services (Video, Broadband Data in addition to Voice) to accelerate development and growth. BSNL has envisioned that the Broadband services rolled as part of the ambitions NIB-II project will be used for high speed Internet connectivity and shall be the primary source of Internet bandwidth and used for connecting broadband customers to the MPLS/VPN through the BRAS. Also will be used for connecting dial VPN customers to the MPLS VPN through the Narrowband RAS. The BSNL’s broadband network cosisits of core routers located at Mumbai, New Delhi, Kolkata, Chennai and Bangalore connected in mesh topology with STM 16 links, with cities in India classified as A1, A2, A3, A4 and other cities.. The network connectivity consists of DSLAM, TIER 2 Switch, Tier 1 Switch, Bras, Core Router and CPE (Customer Premises equipment) consists of Splitter and ADSL modem.

4.0 Cable Modem (CM)

Cable TV connection as last mile infrastructure reaches more people than even the telephone copper infrastructure and can be leveraged in providing cable operators a new business model while giving a stimulus to Broadband penetration. Therefore cable TV network can be used as franchisee network of the service provider for provisioning Broadband services. However all responsibilities for ensuring compliance of terms & conditions of the licensee shall vest with the Licensee. The terms of franchise agreement between Licensee and his franchise shall be settled mutually by negotiation between the two parties involved. Cable Modem (CM) is a device that enables cable operators to provide high-speed Internet access using the coaxial cables used for cable TV. Today, most CMs are external devices that connect to the computer. They will typically have two connections, one to the cable wall outlet and the other to a computer. CMs are attached to the same Cable TV company lines that deliver pictures and sound to yout TV set. High-speed Internet access using CM offers both always-on capability and speed. With this service, users never have to dial up using telephone lines and their cable viewing is not hampered while on line. Speeds for this service vary


depending on the type of cable modem, cable network and traffic load, but are generally faster than those offered by traditional dial-up Internet access.

4.1 Differences between DSL and CM Service High-speed Internet access that uses CM offers shared bandwidth or speed among neighbours on the same cable system. Speed is asymmetric and will vary depending on the number of people on the network. With high-speed Internet access that uses DSL service, you have a dedicated connection to your home. In most cases, however, the performance of DSL based service depends on the distance between end user and phone company central office. Today, high-speed Internet access provided using either DSL or CM typically is offered with a pricing plan that allows without incurring additional usage charges. Many phone and cable companies are offering bundled packages of various services (such as telephone, cable and high-speed Internet access) to lower costs to consumers. High-speed Internet access using CM is targeted towards residential use while DSL-based service is targeted towards residential and business uses.

4.2 Advantages and Disadvantages of having DSL or CM High-speed Internet access provided using DSL and cable modems is much

faster than dial-up modems, however their speeds differ. The distance between the user’s premises and the phone company’s central office is a primary factor in deciding if DSL-based Internet access service is available and its speeds. In contrast, the speed of CM-based Internet access service does not depend on the distance from Cable Company to end-user. Because DSL transmission technology office, competitive providers using DSL technology must coordinate with local phone companies to provide service. Because both versions of high-speed Internet access (DSL and CM) are always on, you may want to check with the provider about security precautions. DSL and CM equipments are generally based on standard specifications and required certification, however, the best advice is to check with the service provider prior to purchase of such equipment. Different varieties of DSL transmission technology provide different maximum speeds, from twice as fast as analog modems to higher than 100 times faster.

4.3 Getting DSL or CM service Contact a provider in your geographical area. For booking of Broadband service

of BSNL there is online register form available on website www.bsnl.co.in, otherwise contact directly to value added services section or nearest customer service center. The provider may be your local telephone service provider or one of its competitors (for DSL-based Internet access), or your local cable company (for CM-based Internet access). There are different high-speed Internet access service available, and the equipment of one provider may not be interoperable in another area or with another provider. Check with your service provider for technical compatibility. Compatible modem may be purchased otherwise service may be affected.


Customer Premises Installation


Broadband Wireless Access Technologies Introduction: Broadband wireless access technologies offer effective, economic & secure

high-speed wireless communications solutions to telecom service providers,

internet service providers, governments, institutes , healthcare & enterprises. It

eliminates the need for costly wire line infrastructure, bringing voice & high-speed

data services to every user within the range of base station. It offers huge

benefits in terms of fast, easy & cost effective, unsurpassed flexibility & reduced

cost of ownership. The solutions are scalable & offers broadband capacity in city

& in remote rural locations.

Learning objective : After going through this topic, the participants will be able to understand:

1) Wireless internet access. 2) Hotspots. 3) Wireless access technologies like Wi-Fi (for LAN) & WiMAX (for MAN). 4) Blue tooth technologies used in PAN. 5) Internet access via satellite.

1.0 Wireless internet access

Wireless access providers connect homes and businesses to the Internet

using wireless or radio connection technology, rather than using technologies

such as coaxial cable (CM) or twisted copper paired telephone lines (DSL).

Wireless providers can use mobile or fixed wireless technologies.

Generally, with fixed wireless technology, a computer, or network of

computers, employ a radio link from the customer’s location to the service

provider. This radio link is usually established between rooftop antennae in direct

line of sight. These rooftop antennae are usually dish shaped with a very narrow

beam of connectivity to prevent interference. The antenna at the customer’s

location is connected by a cable to the local transmitting and receiving radio

equipment. This terminal base station equipment is then connected to the local

computer network.


1.1 Features of wireless access Fixed wireless access customers can be located between 2 and 35 miles from

the wireless provider’s network base station. Fixed wireless provides Internet-access at speeds ranging from one up to 155 mbps. Of course the fixed wireless radio access is dependent on the radio connection and the quality of the radio connection will determine the ultimate quality of service to the customer. 3G technologies provide internet access up to 2 mbps on appropriate digital / cellular phones. Multimedia types of services are available on 3G mobile phones

1.2 Hotspots There are thousands of commercial locations across the country, such as

restaurants, hotels, airports, bookstores, convention centers, city parks and squares, where customers can use laptop computers, handheld devices and other portable computing devices with special “wireless modem cards” to connect to the Internet wirelessly. These locations are called hotspots. Inside the hotspots they can get Internet access on their devices at speed of up to 11 mbps. Also, some wireless providers offer customers packages where they can get wireless Internet access at a collection of different hotspots. The technology that enables the wireless access in hotspots is called “Wi-Fi”. This technology was originally developed as a home networking technology to network home computers wirelessly. There are currently efforts in the industry to develop solutions to extend this technology for longer distances where Wi-Fi can be used as the last-mile solution for Internet access.

Internal Access Point with hub

Ethernet

Radio Link

Customer Premise (Home, business or hotspot)

Subscriber Station With High-Gain Antenna

Internet

Base station /Access Point

Wireless Internet Access


1.3 Wi-Fi Short name for Wireless Fidelity and is meant to be used generically when

referring to any type of 802.11 network, whether 802.11a, 802.11b, 802.11g, etc. The term is promulgated by the Wi-Fi Alliance.

Any products tested and approved as “Wi-Fi Certified” (a registered trademark) by the Wi-Fi Alliance are certified as interoperable with each other, even if they are from different manufactures. A user with “Wi-Fi Certified” product can use any brand of access point with any other brand of client hardware that also is certified. Typically, however, any WiFi product using the same radio frequency (for example, 2.4 GHz for 802.11b or 802.11g, 5 GHz for 802.11a) will work with any other, even if not “WiFi Certified”.

1.4 Wireless IEEE / Ethernet Standards IEEE 802.11 is the initial release of the standard capable of transmissions

of 1 to 2 Mbps and operates in 2.4 Ghz band. It was introduced by IEEE in June 1997. IEEE 802.11a is capable of transmission up to 54 mbps and operates in 5 Ghz band. IEEE 802.11b is capable of transmission up to 11 mbps and operates in 2.4 Ghz band. IEEE 802.11g is capable of transmission up to 54 mbps and operates in 2.4 Ghz band.

1.5 Wi-Fi in outdoor access Network operators have developed two approaches for using Wi-Fi in

outdoor: 1) Wi-Fi with directional antenna or Wi-Fi single hop & 2) Wi-Fi with a mesh-network topology. or Wi-Fi multihop. In this approach the

access points also called nodes are omni direction broadcaster. Each AP acts as a simple router. Meshing allows wireless connectivity between access points. Coverage is over 10 km.

1.6 WiMAX

WiMax (World-wide Interoperability for Microwave Access) is the IEEE 802.16 standards-based wireless technology that provides MAN (Metropolitan Area Network) broadband connectivity. WiMax is an Air Interface for Fixed Broadband Wireless Access Systems, also known as the IEEE Wireless-MAN air interface. WiMax-based systems can be used to transmit signals to as far as 30 miles. So far, WiMax can offer a solution to what is normally called the “last-mile” problem by connecting individual homes and business offices communications.

WiMax covers a couple of different frequency ranges. Basically, the IEEE 802.16 standard addresses frequencies from 10 GHz to 66 GHz. The 802.16a specification, which is an extension of IEEE 802.16, covers bands in the 2 GHz to 11 GHz range. WiMax has a range of up to 30 miles with typical cell radius of 6 to 4 miles.

WiMax supports ATM, Ipv4, Ipv6, Ethernet and VLAN services. So it can provide a rich choice of service possibilities to voice and data network service providers. WiMAX uses orthogonal frequency division multiplexing (OFDM). OFDM is a spread-spectrum technology that bundles data over narrowband carriers transmitted in parallel at different frequencies.

In addition, WiMax provides an ideal wireless backhaul technology to connect 802.11 wireless LANs and commercial hotspots with the Internet.


The WiMax-based solution is set up and deployed like cellular systems using base stations that service a radius of several miles / kilometers. The most typical WiMax-based architecture includes a base station mounted on a building and is responsible for communicating on a point to multi-point basis with subscriber stations located in business offices and homes. The customer Premise Equipment (CPE) will connect the base station to a customer as well; the signal of voice and data is then routed through standard Ethernet cable either directly to a single computer, or to an 802.11 hot spot or a wired Ethernet LAN.

1.7 WiMax Connectivity and Solutions WiMax allows equipment vendors to create many different types of IEEE

802.16 based products, including various configurations of base stations and customer premise Equipment (CPE). WiMax also allows the services provider to deliver many types of wireless access services. WiMax can be used on a variety of wireless broadband connections and solutions:

• “Last Mile” Broadband Access Solution-Metropolitan-Area Network (MAN) connections to home and business office, especially in those areas that were not served by cable or DSL or in areas where the local telephone company may need a long time to deploy broadband service. The WiMax-based wireless solution makes it possible for the service levels in short times with client request.

• Backhaul network for cellular base stations, bypassing the public Switched Telephone Network (PSTN); the cellular service providers can look to wireless backhaul as a more cost-effective alternative. The robust WiMax technology makes it a nice choice for backhaul for hotspots as well as point-to-point backhaul solutions.

• Backhaul enterprise connections to the Internet for WiFi hotspots. It will allow users to connect to a wireless Internet service provider even when they roam outside their home or business office.

• A variety of new business services by wireless Internet service provider. Unlike WiFi, WiMax’s range is typically measured in miles rather than feet. The

main distinction of the difference between the two standards means that WiFi is focused on a local Area Network (LAN) technology and that WiMax is a MAN technology.

WiMax-based solutions include many other advantages, such as robust security features, good QoS (Quality of Service), and mesh and smart antenna technology that will allow better utilization of the spectrum resources. Also, the WiMax-based voice service can work on either traditional Time Division Multiplexed (TDM) voice or IP-based Voice, also known as Voice over IP (VoIP).

The WiMAX standard enables system vendors to create many different types of WiMAX-based products, including various configurations of base stations and Customer Premise Equipment (CPE). WiMAX supports a variety of wireless broadband connections such as:

� High-bandwidth Metropolitan-Area Networks (MANs) to home and

small-business users, replacing DSL and cable modems. � Backhaul networks for cellular base stations, bypassing the public

switched telephone network. � Backhaul connections to the Internet for WiFi hotspots.


1.8 Blue tooth, WPAN, IEEE 802.15

Blue tooth is a short range (PAN) wireless technology. It is an IEEE 802.15 standard technology. It is designed for:

- Interconnecting computer and peripherals. - Interconnecting various handhelds. 1.9 WWAN IEEE 802.20 is the wireless standard for wide area network. 2.0 Internet access via satellite Very Small Aperture Terminal (VSAT) & Direct-To-Home (DTH) provide

broadband & internet services via satellite. The customer premises equipment / devices required are (1) two to three feet dish antenna often called base station.(2) a satellite internet modem with the condition that the line of sight is clear between the base station & provider’s satellite.

2.1 Advantage & disadvantages Advantage: It can serve remote & inaccessible areas. Disadvantages: - It is based on line of sight technology. - It is affected by weather. - It is costly.

-Transmission delay is higher than other alternatives.

Summary Wireless in the last / first mile is suitable in areas not served by cable or DSL & where deployment of wired line needs a long time. Wi-Fi (IEEE 802.11) is the wireless standard for LAN. Bluetooth (IEEE 802.15) is the wireless standard for PAN. WiMAX (IEEE 802.16) is the wireless standard for MAN. Hotspots uses Wi-Fi technology. Any product tested & approved by Wi-Fi alliance is termed as Wi-Fi certified. VSAT & DTH provide internet access via satellite.

Reference: 1. Wi-Max and Wi-Fi wireless mobility online document www.wifi-org and

www.wimax.org 2. www.broadband.org 3. Broadband policy 2004 online document www.dotindia.com 4. http://www.thestandard.com/movabletype/datadigest/archives/003203.php 5. http://standards:ieee.org.

Section-4

Chapter-2

TCP/IP, IP Addressing & Ethernet

E3E4 TCP/IP/Ethernet Ver2 28.02.2008 1 of 10

LAN & Inter working Devices

Networking means interconnection of computers. These computers can be linked together for

different purposes and using a variety of different cabling types.

The basic reasons why computers need to be networked are:

♦ To share resources (files, printers, modems, fax machines, storage etc.)

♦ To share applications (MS Office, Adobe Publisher, Oracle etc.)

♦ Increase productivity (makes it easier to share data amongst users)

Take for example a typical office scenario where a number of users require access to some

common information. As long as all user computers are connected via a network, they can

share their files, exchange mail, schedule meetings, send faxes and print documents all from

any point of the network. Small networks are often called Local Area Networks (LAN). A LAN

is a network allowing easy access to other computers or peripherals. The typical

characteristics of a LAN are:

♦ Physically limited distance (< 2km)

♦ High bandwidth (> 1mbps)

♦ Inexpensive cable media (coax or twisted pair)

♦ Data and hardware sharing between users

♦ Owned by the user

The factors that determine the nature of a LAN are:

♦ Topology

♦ Transmission medium

♦ Medium access control technique

LAN Architecture The layered protocol concept can be employed to describe the architecture of a LAN, wherein

each layer represents the basic functions of a LAN.

LAN Topologies

The common topologies for LANs are bus, tree, ring, and star. The bus is a special case of the

tree, with only one trunk and no branches.

Bus and Tree Topologies

Bus and Tree topologies are characterized by the use of a multi-point medium. For the bus all

stations attach, through appropriate hardware interfaces known as a Tap, directly to a linear

transmission medium, or bus. Full-duplex operation between the station and the tap permits

data to be transmitted onto the bus and received from the bus.

Fig. 3 (a) Bus

Tap

Flow of data

Station

Terminating

Resistance


The tree topology is a generalization of the bus topology. The transmission medium is a

branched cable with no closed loops. The tree layout begins at a point known as the head-end,

where one or more cable start, and each of these may have branches. The branches in turn

may have additional branches.

Ring Topology In the ring topology, the network consists of a set of repeaters joined by point-to point links

in a closed loop. The repeater is a comparatively simple device, capable of receiving data on

one link and transmitting them, bit by bit, on the other link as quickly as they are received,

with no buffering at the repeater. The links are unidirectional, i.e. data is transmitted in one

direction (clockwise or counter-clockwise).

Each station is attached to the network at a repeater and can transmit data onto the network

through that repeater.

Star Topology

In the Star type topology, each station is directly connected to a common central node.

Typically, each station attaches to a central node, referred to as the star coupler, via two

point-to point links, one for transmission in each direction.

Fig. 3 (b) Tree

Central Hub, Switch/

Repeater

Ring


Medium Access Control

All LANs consist of a collection of devices that have to share the network’s transmission

capacity. Some means of controlling access to the transmission medium is needed to provide

for an orderly and efficient use of that capacity. This is the function of medium access

control (MAC) protocol.

The key parameters in any medium access control technique are-where and how. Where refers

to whether control is in a centralized or distributed fashion.

BASIC NETWORK COMPONENTS

There are a number of components, which are used to build networks. An understanding of

these is essential in order to support networks.

Network Adapter Cards (NIC): A network adapter card plugs into the workstation, providing

the connection to the network. Adapter cards come from many different manufacturers, and

support a wide variety of cable media and bus types such as - ISA, MCA, EISA, PCI, and

PCMCIA. New cards are software configurable, using a software programs to configure the

resources used by the card. Other cards are PNP (plug and Play), which automatically

configure their resources when installed in the computer, simplifying the installation.

Cabling: Cables are used to interconnect computers and network components together. There

are 3 main cable types used today:

♦ Twisted pair

♦ Coax

♦ Fiber optic

The choice of cable depends upon a number of factors like cost, distance, number of

computers involved, speed, bandwidth i.e. how fast data is to be transferred etc.

REPEATERS

Repeaters extend the network segments. They amplify the incoming signal received from one

segment and send it on to all other attached segments. This allows the distance limitations of

network cabling to be extended. There are limits on the number of repeaters that can be

used.

Fig. Use of Repeaters in a Network

Repeater Main Network Segment

Workstation


Summary of Repeater features:

♦ Increases traffic on segments

♦ Have distance limitations

♦ Limitations on the number of repeaters that can be used

♦ Propagate errors in the network

♦ Cannot be administered or controlled via remote access

♦ Cannot loop back to itself (must be unique single paths)

♦ No traffic isolation or filtering is possible

BRIDGES: Bridges interconnect Ethernet segments. The IEEE 802.1D specification is the

standard for bridges. The bridge builds up a table that identifies the segment to which the

device is located on. This internal table is then used to determine which segment incoming

frames should be forwarded to. The size of this table is important, especially if the network

has a large number of workstations/ servers.

Fig. Use of Bridge in a Network

The advantages of bridges are

♦ Increase the number of attached workstations and network segments

♦ Since bridges buffer frames, it is possible to interconnect different segments which

use different MAC protocols

♦ Since bridges work at the MAC layer, they are transparent to higher level protocols

♦ By subdividing the LAN into smaller segments, overall reliability is increased and the

network becomes easier to maintain

♦ Used for non routable protocols like NETBEUI which must be bridged

♦ Help in localizing the network traffic by only forwarding data onto other segments as

required (unlike repeaters)

ROUTERS: In an environment consisting of several network segments with differing

protocols and architectures, a bridge may not be adequate for ensuring fast communication

among all of the segments. A network this complex needs a device, which not only knows the

address of each segment, but also determines the best path for sending data and filtering

broadcast traffic to the local segment. Such a device is called a router. Routers can switch

and route packets across multiple networks. They do this by exchanging protocol-specific

information between separate networks. A router uses a table to determine the destination

address for incoming data. The table lists the following information:

BRIDGE

Network Segment A Network Segment B


♦ All known network addresses

♦ How to connect to other networks

♦ The possible path between those routers

♦ The cost of sending data over those paths

The router selects the best route for the data based on cost and available paths.

Routers can provide the following functions of a bridge:

♦ Filtering and isolating traffic

♦ Connecting network segments

HUBS: There are many types of hubs. Passive hubs are simple splitters or combiners that

group workstations into a single segment, whereas active hubs include a repeater function and

are thus capable of supporting many more connections.

Ethernet: Ethernet is a family of frame-based computer networking technologies for local

area networks (LANs). The name comes from the physical concept of the ether. It defines a

number of wiring and signaling standards for the physical layer, through means of network

access at the Media Access Control (MAC)/Data Link Layer, and a common addressing format.

Ethernet is standardized as IEEE 802.3. Ethernet follows a simple set of rules that govern its

basic operation. To better understand these rules, it is important to understand the basics of

Ethernet terminology.

• Medium - Ethernet devices attach to a common medium that provides a path along which

the electronic signals will travel. Historically, this medium has been coaxial copper cable,

but today it is more commonly a twisted pair or fiber optic cabling.

• Segment - We refer to a single shared medium as an Ethernet segment.

• Node - Devices that attach to that segment are stations or nodes.

• Frame - The nodes communicate in short messages called frames, which are variably sized

chunks of information.

Frames are analogous to sentences in human language. In English, we have rules for

constructing our sentences: We know that each sentence must contain a subject and a

predicate. The Ethernet protocol specifies a set of rules for constructing frames. There are

explicit minimum and maximum lengths for frames, and a set of required pieces of information

that must appear in the frame. Each frame must include, for example, both a destination

address and a source address, which identify the recipient and the sender of the message.

The address uniquely identifies the node, just as a name identifies a particular person. No two

Ethernet devices should ever have the same address.


The 7 Layers of the OSI Model The OSI, or Open System Interconnection, model defines a networking framework for

implementing protocols in seven layers. Control is passed from one layer to the next, starting

at the application layer in one station, proceeding to the bottom layer, over the channel to the

next station and back up the hierarchy.

Application (Layer

7)

This layer supports application and end-user processes. Communication

partners are identified, quality of service is identified, user authentication

and privacy are considered, and any constraints on data syntax are identified.

Everything at this layer is application-specific. This layer provides application

services for file transfers, e-mail, and other network software services.

Telnet and FTP are applications that exist entirely in the application level.

Tiered application architectures are part of this layer.

Presentation

(Layer 6)

This layer provides independence from differences in data representation

(e.g., encryption) by translating from application to network format, and vice

versa. The presentation layer works to transform data into the form that the

application layer can accept. This layer formats and encrypts data to be sent

across a network, providing freedom from compatibility problems. It is

sometimes called the syntax layer.

Session

(Layer 5) This layer establishes, manages and terminates connections between

applications. The session layer sets up, coordinates, and terminates

conversations, exchanges, and dialogues between the applications at each end.

It deals with session and connection coordination.

Transport

(Layer 4)

This layer provides transparent transfer of data between end systems, or

hosts, and is responsible for end-to-end error recovery and flow control. It

ensures complete data transfer.

Network

(Layer 3) This layer provides switching and routing technologies, creating logical paths,

known as virtual circuits, for transmitting data from node to node. Routing and

forwarding are functions of this layer, as well as addressing, internetworking,

error handling, congestion control and packet sequencing.

Data Link

(Layer 2)

At this layer, data packets are encoded and decoded into bits. It furnishes

transmission protocol knowledge and management and handles errors in the

physical layer, flow control and frame synchronization. The data link layer is

divided into two sublayers: The Media Access Control (MAC) layer and the

Logical Link Control (LLC) layer. The MAC sublayer controls how a computer on

the network gains access to the data and permission to transmit it. The LLC

layer controls frame synchronization, flow control and error checking.

Physical

(Layer 1) This layer conveys the bit stream - electrical impulse, light or radio signal --

through the network at the electrical and mechanical level. It provides the

hardware means of sending and receiving data on a carrier, including defining

cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are

protocols with physical layer components.


Table below illustrates all the major TCP/IP Internet protocols and associates a layer of the

architecture with each. Application-layer protocols are divided into two groups; first, those

use TCP second use UDP.

Layer

No.

Layer Protocols

1 Application Protocols Using TCP at Layer 4: FTP, SMTP, TELNET, HTTP

Protocols Using UDP at Layer 4: TFTP, SNMP, NFS, DNS

2 Transport TCP (Reliable & Connection Oriented), UDP (Unreliable & Connectionless

3 Network IP, ARP, RARP, ICMP, IGMP

4 Data

5 Physical

Protocols defined by underlying networks

User Service Application

User service applications include the following.

• TELENET – provides a remote logon capability

File transfer protocol (FTP) – provides a reliable file transfer capability

User Service Application

User service applications include the following.

o TELENET – provides a remote logon capability.

o File transfer protocol (FTP) – provides a reliable file transfer capability

o X window system – provides a graphical interface to applications.

o Trivial file transfer protocol (TFTP) – provides an unreliable, simple file transfer

capability.

o Network file system (NFS) – provides remote virtual storage capability.

o Simple message transfer protocol (SMTP) – provides electronic mail capability.

Utility Applications

Utility applications include the following.

1. Simple network management protocol (SNMP) – provides network management

information.

2. Boot protocol (BOOTP) – provides remote loading capability for diskless workstations.

3. Domain name service (DNS) – provides directory assistance for Internet addresses using

local names.

4. Address resolution protocol (ARP) – provides a physical address from an IP address.

5. Reverse address resolution protocol (RARP) – provides an IP address from a physical

device address.

In theory, all application protocols could use either the UDP or the TCP. The reliability

requirements of the application dictates, which transport layer protocol is used. For example,

some applications, such as the domain name service (DNS), may either UDP or TCP. The UDP

provides an unreliable, connectionless transport service, while the TCP provides a reliable, in-

sequence, and connection-oriented service. Because the UDP is unreliable, many of the

application layer protocols only use TCP, for example, FTP and TELNET. For the application

layer protocols that do not require a reliable service, they use only UDP, for example, TFTP,

SNMP, VoIP etc.


Transport Layer Protocols

This session provides a description of the transport layer protocols, user datagram protocol

(UDP), and transmission control protocol (TCP). The selection by an applications program to

use either UDP or TCP is based primarily on the requirement for reliability.

USER DATAGRAM PROTOCOL (UDP)

The UDP provides application programs with a transaction oriented, single-shot datagram type

service. The service is similar to the IP in that it is connectionless and unreliable. The UDP is

simple, efficient and ideal for application programs such as TFTP and DNS. An IP address is

used to direct the user datagram to a particular machine, and the destination port number in

the UDP header is used to direct the UDP datagram (or user datagram) to a specific

application process (queue) located at the IP address. The UDP header also contains a source

port number that allows the receiving process to know how to respond to the user datagram.

There is no acknowledgement, flow control, message continuation, or other sophisticated

attributes offered by the TCP.

The UDP operates at the transport layer and has a unique protocol number in the IP header

(number 17). This enables the network layer IP software to pass the data portion of the IP

datagram to the UDP software. The UDP uses the destination port number to direct the from

the IP datagram (user datagram) to the appropriate process queue. Since there is no sequence

number or flow control mechanism, the user of UDP must either not need reliability or self-

service.

TRANSMISSION CONTORL PROTOCOL (TCP)

TCP provides traditional circuit-oriented data communications service to programs. TCP

provides a virtual circuit for programs, which is called a connection. The communication on a

connection is asynchronous in that a segment sent does not have to be acknowledged before

sending the next segment. Unlike programs that use UDP, those using TCP enjoy a connection

service between the called and calling program, error checking, flow control, and interrupt

capability. A connection can be initiated simultaneously at both ends and have the window size

for flow control dynamically adjusted during the connection.

TCP Connection

The source and destination port numbers in TCP header identify the application programs at

each end of the TCP connection. The IP address in the IP datagram is used to deliver the TCP

segment to the correct machine. The protocol number in the IP datagram directs the segment

to TCP. The source and destination port numbers in the TCP header are used to direct the

segment data to the appropriate application layer entity (software program). Since the port

number in the TCP header is a 16-bit field, there could be, theoretically, up to 65536

connections between two peer TCP layers using the same set of IP addresses.

Source/Destination Port Numbers

Each port number is an unsigned integer occupying 16 bits.

INTERNET CONTROL MESSAGE PROTOCOL (ICMP)

The Internet is an autonomous system without central control. The ICMP provides a vehicle

for the software of intermediate gateways and hosts to communication. The communication is

used to regulate traffic; correct routing tables, and checks the availability of a host.


IP Addressing Introduction

We all know that each telephone, be it landline or mobile has to have a unique number. In India

we have a ten digits numbering scheme, which implies that mobile as well as landline number

(including STD code) will be of ten digits. For example 11 23456789 is a number of Delhi.

Internationally, this number will be known as 91 11 23456789 i.e. ISD code needs to be

prefixed. Therefore in the world each such number is unique. Any phone can reach any other

if others number is known. We all remember the days when telephone numbers were of 5

digits. Digits were added to accommodate more numbers. On the same lines, in Internet we

need to have unique address for each PC connected to it. IP addressing is the scheme to

achieve it.

IP Addressing

Each host on the Internet is assigned an officially sanctioned 32-bit integer address

called its Internet Address or IP address. This addressing scheme is also known as Ipv4 i.e.

Internet Protocol version 4. The IP address consists of two parts network part and host part.

The combination is unique: no two machines can have the same IP address. The address is

coded to allow a variable allocation of bits to specify network and host.

The IP address scheme is to break up the binary number into pieces and represent each piece

as a decimal number. A natural size for binary pieces is 8 bits, which is the familiar byte or

octet (octet is the telecommunication term, but two words can be used interchangeably). So

let’s take our binary number, write it using groups of 8 bits, and then represent each group as

a decimal number:

Example 1: 140.179.220.200

It is sometimes useful to view the values in their binary form.

140 .179 .220 .200

10001100.10110011.11011100.11001000

Every IP address consists of two parts, one identifying the network and one identifying the

host. The Class of the address and the subnet mask determine which part belongs to the

network address and which part belongs to the host address.

10111100 00011010 000111110 00111100

156 26 30 60

We can use a dot as a separator. Now our IP address has the form

Example 2: 156.26.30.60 that is referred to as the dotted decimal notation.

IP Address should be hierarchical

For a protocol to be routable, its address structure must be hierarchical, meaning that the

address must contain at least two parts: the network portion and the host portion. A host is

an end station such as a computer workstation, a router or a printer, whereas a network

consists of one or more hosts.

Address Classes: This encoding provides flexibility in assigning addresses to host and allows

a mix of network sizes on an Internet. In particular, the three network classes are best

suited to the following conditions:

• Class A: Few networks, each with many hosts. It allows for up to 126 networks with 16

million hosts each.

• Class B: Medium number of networks, each with a medium number of hosts. It allows for up

to 16,328 networks with up to 64K hosts each;

E3E4 TCP/IP/Ethernet Ver2 28.02.2008 10 of

10

• Class C: Many networks, each with a few hosts. It allows for up to 2 millions networks with

up to 254 hosts each;

• Class D: Reserved for IP Multicasting.

• Class E: Reserved for future use. Addresses beginning with 1111 are reserved for future

use.

The Following table lists the capabilities for class A, B and C addresses.

Class Networks Hosts

A 126 16,777,214

B 16,384 65,534

C 2,097,152 254

More about IP address Classes Addresses beginning with 01111111, or 127 decimal, are reserved for loopback and for

internal testing on a local machine. [You can test this: you should always be able to ping

127.0.0.1, which points to yourself] Class D addresses are reserved for multicasting. Class E

addresses are reserved for future use. They should not be used for host addresses.

In the example, 140.179.220.200 is a Class B address so by default the Network part of the

address (also known as the Network Address) is defined by the first two octets (140.179.x.x)

and the host part is defined by the last 2 octets (x.x.220.200).

In order to specify the network address for a given IP address, the host section is set to all

"0"s. In our example, 140.179.0.0 specifies the network address for 140.179.220.200. When

the host section is set to all "1"s, it specifies a broadcast that is sent to all hosts on the

network. 140.179.255.255 specifies the example broadcast address. Note that this is true

regardless of the length of the host section.

Private Subnets: There are three IP network addresses reserved for private networks. The

addresses are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. They can be used by anyone

setting up internal IP networks, such as a lab or home LAN behind a Router performing NAT

(Network Address Translation) or proxy server.

Subnetting: Subnetting an IP Network can be done for a variety of reasons, including

organization, use of different physical media (such as Ethernet, FDDI, WAN, etc.),

preservation of address space, and security. The most common reason is to control network

traffic.

Ipv6: The heavy use of PCs connected on Internet has saturated the address space available

in IPv4 address format. A new address scheme known as Ipv6 has been introduced. This

address length is 128 bits. The format of address is

2145:00D5:2F3B:0000:0000:00FF:EF00:98F3

Removing zeros can also reduce the IPv6 address. Zeros can be removed when they are

leading in and within any 16-bit block. These removed zeros are indicated by :: sign in the

address. The address from the previous example could be reduced using this to the following

representation. Note that in the example the block of EF00 does not lose its zeros because

they are at the end of the block.

IPv6 Address with Leading Zeros Removed: 2145:D5:2F3B:0:0:FF:EF00:98F3

IPv6 Address with Compressed and Removed Zeros: 2145:D5:2F3B::FF:EF00:98F3

Section-4

Chapter-3

NIB and Multiplay

E3E4 NIB and Multiplay, Ver2 28.02.2008 1 of 7

Broadband Core Network

Core of BSNL’s Broadband service is National Internet Backbone (NIB). NIB is a mission to

build world-class infrastructure to help accelerate the Internet revolution in India. It has

following features:

1. It provides a diversified range of Internet access services including support for VPN

(Layer-2, Layer-3 and Dialup and Broadband services)

2. It also offers SLA Reports including security, QoS (quality of service) and any to any

connectivity.

3. Offers fully managed services to customers.

4. It offers services like bandwidth on demand etc. over the same network.

5. The network is capable of on-line measurement and monitoring of network parameters

such as latency, packet loss, jitter and availability so as to support SLAs with customers

6. The routers support value added services such as VPNs, Web and content hosting,

Voice over IP, Multicast etc.

7. Value Added Services

a. Encryption Services

b. Firewall Services

c. Multicast Services

d. Network Address Translation (NAT) Service that will enable private users to

access public networks

8. Messaging Services

9. Internet Data Centre Services at Bangalore, Delhi and Mumbai.

10. Broad Band Services

a. Broadcast TV using IP Multicasting service

b. Multicast video streaming services

c. Interactive Distant learning using IP multicasting Services

d. Video on demand

e. Interactive gaming service

NIB-II has been implemented in four projects

Name of project Description

Project 1 MPLS based IP Infrastructure (The backbone consisting of Core & Edge

Routers)

Project 2.1 Narrowband Access (Dialup Remote Access)

Project 2.2 Broadband Access (DSL Access)

Project 3 Messaging, Storage, Provisioning, Billing, Security, Order Management,

Enterprise Management, AAA, Help Desk and Inventory Management.

Network Architecture

The cities in India have been classified in six types namely A1, A2, A3, A4, B1, B2. Important

aspects are given below:

1. A1 – 5 Core cities

a. Bangalore, Chennai, Mumbai, Delhi, Kolkatta

2. A2/A3 – 9 next level core cities

a. Pune, Hyderabad, Ahmedabad, Ernakulam, Lucknow, Jaipur, Indore, Jullundur,

Patna


3. A4 – 10 Major cities

4. B1, B2 – 47 other cities

5. A1 city core routers are fully meshed between locations on STM-16

6. IGW – International Gateway Router – Connectivity to Internet is through this router

7. IXP – Internet Exchange Point – ISP’s connect each other through this router

8. IDC – Internet Data Center – for connecting to BSNL Data Centers

9. B1 and B2 cities have only EDGE routers.

10. All Core locations also have edge routers

11. Primary Network Operating center at Bangalore and Disaster Recovery is at Pune

NIB2 Expansion and Year 2 Order Overview

1. 29 locations added which makes the total to 100

2. Core backbone is getting aligned to BSNL Transmission (DWDM) network

3. 24 City core network increased to 29

4. All 29 city core network links are STM-16 (ie STM1 connectivity of A4 cities will be

upgraded to STM16)

5. New 5 Cities are Belgaum, Dehradun, Rajkot, Jodhpur, Jabalpur

Components of Broad Band Access Network

1. Broad band Remote Access Server (BBRAS)

2. Gigabit and Fast Ethernet Aggregation Switches (LAN Switches).

3. Digital Subscriber Line Access Multiplexers (DSLAMs)

4. SSSS/SSSC (Subscriber Service Selection System/ Centre)

5. Servers for AAA, LDAP at NOC.

6. Provisioning and configuration management at NOC.

7. DSL CPEs (MODEM)

8. The DSLAMs will in general be collocated with existing PSTN exchanges, which

provide last mile access to customers over copper wire up to average span lengths of 3

kms.

9. All DSLAMs will be aggregated through a FE interface except 480 port DSLAM,

which will be aggregated through Gigabit Ethernet Interface.

10. The 240 ports DSLAM will have two number of FE interface.

11. The FX or GBIC module in DSLAM and LAN switch capable of driving upto 10km on

a single mode fibre.

12. The SX or GBIC module in LAN Switch used for connecting Tier2 to Tier1. In bigger

cities like A1, A2, A3 and A4, one BBRAS per city will be deployed initially.

14. There will be no BBRAS at B1 and B2 cities.

15. The DSLAMs in B1.B2 and other lower hierarchical cities will be aggregated through

Layer 2 switches, and will be connected to the nearest BBRAS of A cities on Ethernet

over SDH.

16. The BRAS shall terminate the PPP sessions initiated by the customer and extend the

connection further to MPLS VPN/ Internet as desired by the customer.

BBRAS: A Broadband Remote Access Server (BBRAS) routes traffic to and from the digital

subscriber line access multiplexers (DSLAM) on an Internet service.

DSLAM: Digital Subscriber Line Access Multiplexer. Specifically, a device that takes a

number of ADSL subscriber line and concentrates these to a single ATM line.

CPE: Customer Premises Equipment - Any equipment provided by the customer at their

premises.

GBIC: Gigabit Interface Converter; a Fiber Channel optical or copper transceiver that is easily

swapped to offer a flexible choice of copper or fiber optic media.


Starting NIB connectivity diagram. Expansion is a continuous process hence many new sites

keep getting added.

Block Schematic of Broadband Access Network


BROADBAND MULTIPLAY Learning Objective

1. What is broadband Triple Play / Multiplay

2. Service offered in Broadband Triple play

3. Components of broadband triple play

4. What is IPTV

5. What is VoIP

What is broadband triple play / Multiplay The triple play service means providing the following service to the customer: -

1. Data (Internet)

2. Voice (VoIP and not the PSTN which is already provided on broadband also)

3. Video (IPTV, VoD or in general live broadcast and stored broadcasting using video

streaming protocols)

Components of Broadband Multiplay

Network Architecture of Broadband Multiplay

The BSNL’s Broadband multiplay network consists of the following components: - a. L3PE (MCR / PE Router of NIB-2 Project 1 – Supplied by HCL)

b. BNG – Broadband Network Gateway

i. Connects Multiplay Network to NIB2 Backbone (Project 1) through L3PE

c. RPR Tier-1 Switch

i. Provides connectivity from BNG to Tier –2 network

d. RPR Tier-2 Switch

e. OC LAN Tier-2 Switch

f. DSLAM

g. ADSL CPE

h. DSL Tester


Changes in Broadband Multiplay viz-a-viz broadband 1. T1 & T2 changed from star topology to RPR ring topology – High reliability

2. IP-DSLAM connected on GE interface as compared to FE interface.

3. BNG behaves as customer edge router whereas BRAS was a PE Router.

4. BRAS were present at 23 “A” locations only whereas BNG is present upto “B” type cities.

Services: Video

a. IPTV or TVoIP

1. IPTV or TVoIP delivers television programming to households via broadband

connection using Internet protocols.

2. It requires a subscription and IPTV set-top box (STB), this box will connect to the

home DSL line and is responsible for reassembling the packets into a video stream and

then decoding the contents

3. IPTV is typically bundled with other services like Video on Demand (VOD), Voice

Over IP (VOIP) or digital Phone, and Web access.

4. IPTV viewers will have full control over functionality such as rewind, fast-forward,

pause, and so on.

5. If you've ever watched a video clip on your computer, you've used an IPTV system in

its broadest sense.

6. The video stream is broken up into IP packets and dumped into the core network, which

is a massive IP network that handles all sorts of other traffic (data, voice, etc.)

b. VOD (Video on Demand) Video on Demand service allows the user the luxury of watching the movie of his / her

choice at his / her convenience.

Difference between VOD on Broadband and DTH (e.g. Dish TV/Tata sky) In DTH, as it is broadcasting and not communication so the request for VOD has to be

registered through some other mean than the Set top Box say can be through phone call, SMS

or Internet and the same four to five movies are broadcasted and the viewers have to choose

among them only and at predefined timings.

In true VOD, as offered by BSNL, the set-top box behaves just like a DVD player and

viewer can select a movie from the boutique, view it at his / her desired time and day, pause it,

rewind it, forward it or can have the exactly same experience has viewing from a personalized


DVD player. This is only possible because of the two-way communication between the set-top

box and the server. In BSNL one has a choice of selecting from hundreds of movies while

VOD offered by DTH providers may have only few movies to offer.

Set-top Box The set-top box is a smart solid-state device that acts as the gateway to a host of

services offered on the BSNL Multiplay network. On one side the set-top box interfaces with

the television using the 3-RCA or the S-Video ports, and on the other side it is connected to

broadband ADSL modem via the Ethernet port.

BSNL franchisee in Pune has named the set-top box as WICE Box (Window for Information,

Communication and Entertainment) and supports all sorts of inputs like audio, video, tablet

data, text data, pointer devices etc. it has a USB port and a microphone and headphone jack in

addition to essential ports. In future, it will be possible to connect keyboard, mouse, web cams,

pen-drives and other such devices for various applications that will be provided on the box.

The WICE box is fully upgradeable through the network. This means, any new application

launched will be directly uploaded into WICE box without getting the box to service center.

All software upgrade will be handled this way.

WICE. Box Option-I (Outright Purchase) S/No. Item Charges

1. Installation and Activation Charges (Non-Refundable) Rs. 600

2. WICE. Box sale Rs. 3950

WICE. Box Option-II (Rental) 1. Installation and Activation Charges (Non-Refundable) Rs. 600

2. Security Deposit for WICE. Box (Refundable) Rs. 1500

3. Fixed Monthly Charge for WICE. Box Rs. 99

Service and other taxes will be charged separately as applicable

Service Charges S/No. Service Name Scheme Charges Remarks

1. Digital TV Rs. 150* All major TV channels

Any two movies free from a list of movies

2. Plan 2 Rs. 325* All major TV channels

Movies worth Rs 220/- free

* Service and other taxes extra

Services: - Voice

VoIP (Voice over IP) 1. The technology used to transmit voice conversations over a data network using the Internet

Protocol.

2. A category of hardware and software that enables people to use the Internet as the transmission

medium for telephone calls.

3. VoIP works through sending voice information in digital form in packets,

4. VoIP also is referred to as Internet telephony, IP telephony, or Voice over the Internet (VOI)


Benefits of VoIP 1. Cost reduction

a. Toll by-pass

b. WAN Cost Reduction

2. Operational Improvement

a. Common network infrastructure

b. Simplification of Routing Administration

3. Business Tool Integration

a. Voice mail, email and fax mail integration

b. Web + Call

c. Mobility using IP

BSNL Plans:

BSNL has planned to roll out this service in 898 cities progressively.

The service is being provided at Pune, Chennai, Bangalore, Kolkatta, Hyderabad and Ahemdabad.

This service is being provided through franchisees. Many cities already have franchisees for

broadband content and they can offer this service. A pool of private IP addresses will be

allotted by BSNL to the said franchisee, which will be used for allotting IP address to the IPTV

customer.

Section-4

Chapter-4

MPLS- VPN

E3E4 MPLS VPN Ver2 28.02.2008 1 of 7

Multi-Protocol Label Switching (MPLS)

What is MPLS? Multi Protocol Label Switching (MPLS) is a data-carrying mechanism in packet-switched

networks and it operates at a TCP/IP layer that is generally considered to lie between

traditional definitions of Layer 2 (data link layer) and Layer 3 (network layer or IP Layer),

and thus is often referred to as a "Layer 2.5" protocol. It was designed to provide a unified

data-carrying service for both circuit-based clients and packet-switching clients, which

provide a datagram service model. It can be used to carry many different kinds of traffic,

including IP packets, as well as native ATM, SONET, and Ethernet frames. The Internet

has emerged as the network for providing converged, differentiated classed of services to

user with optimal use of resources and also to address the issues related to Class of service

(CoS) and Quality of Service (QoS). MPLS is the technology that addresses all the issues in

the most efficient manner.

MPLS is a packet-forwarding technology that uses labels to make data forwarding

decisions. With MPLS, the Layer 3 header analysis (IP header) is done just once (when the

packet enters the MPLS domain).

What is a MPLS header? MPLS works by prefixing packets with an MPLS header, containing one or more 'labels'.

This is called a label stack. Each label stack entry contains four fields:

- 20-bit label value (This is MPLS Label)

- 3-bit Experimental field used normally for providing for QoS (Quality of Service)

- 1-bit bottom of stack flag. If this is 1, signifies that the current label is the last in the

stack.

- 8-bit TTL (time to live) field.

Various functions & Routers in MPLS Label A label identifies the path a packet should traverse and is carried or encapsulated in a

Layer-2 header along with the packet. The receiving router examines the packet for its label

content to determine the next hop. Once a packet has been labelled, the rest of the journey

of the packet through the backbone is based on label switching.

Label Creation Every entry in routing table (build by the IGP) is assigned a unique 20-bit

label either per platform basis or per interface basis.

SWAP: The Incoming label is replaced by a new Outgoing label and the packet is

forwarded along the path associated with the new label.

PUSH A new label is pushed on top of the packet, effectively "encapsulating" the packet in

a layer of MPLS.

POP The label is removed from the packet effectively "de-encapsulating". If the popped

label was the last on the label stack, the packet "leaves" the MPLS tunnel.

LER A router that operates at the edge of the access network and MPLS network LER

performs the PUSH and POP functions and is also the interface between access and MPLS

network, commonly know as Edge router.

LSR An LSR is a high-speed router device in the core of an MPLS network, normally

called Core routers. These routers perform swapping functions and participate in the

establishment of LSP.

Ingress / Egress Routers: The routers receiving the incoming traffic or performing the first

PUSH function are ingress routers and routers receiving the terminating traffic or

performing the POP function are Egress routers. The same router performs both

functionality i.e. Ingress and Egress. The routers performing these functions are LER.

FEC The forward equivalence class (FEC) is a representation of a group of packets that

share the same requirements for their transport. All packets in such a group are provided the

E3E4 MPLS VPN Ver2 28.02.2008 2 of 7

same treatment en route to the destination. As opposed to conventional IP forwarding, in

MPLS, the assignment of a particular packet to a particular FEC is done just once, as the

packet enters the network at the edge router.

MPLS performs the following functions: 1. Specifies mechanisms to manage traffic flow of various granularities, such as flows

between different hardware, machines, or even flows between different applications.

2. Remains independent of the Layer-2 & layer-3 protocols.

3. Provides a means to map IP addresses to simple, fixed-length labels used by different

packet-forwarding and packet-switching technologies

4. Interfaces to existing routing protocols such as resource reservation protocol (RSVP)

and open shortest path first (OSPF).

5. Supports the IP, ATM, and frame- relay Layer-2 protocols.

Label Distribution Protocol (LDP): The LDP is a protocol for the distribution of label

information to LSRs in a MPLS networks. It is used to map FECs to labels, which, in turn,

create LSP. LDP sessions are established between LDP peers in the MPLS network (not

necessarily adjacent). The peers exchange the following types of LDP messages:

Discovery messages – announce and maintain the presence of an LSR in a network

Session messages – establish, maintain, and terminate sessions between LDP peers

Advertisement messages – create, change, and delete label mappings for FECs.

Notification messages – provide advisory information and signal error information

Traffic Engineering Traffic engineering is a process that enhances overall network utilization by attempting to

create a uniform or differentiated distribution of traffic throughout the network. An

important result of this process is the avoidance of congestion on any one path. It is

important to note that traffic engineering does not necessarily select the shortest path

between two devices. It is possible that, for two packet data flows, the packets may traverse

completely different paths even though their exposed or less used network segments can be

used and differentiated services can be provided.

MPLS Operation : The following steps must be taken for a data packet to travel through

an MPLS domain. Label creation and distribution, Table creation at each router, Label-

switched path creation, Label insertion/table lookup and Packet forwarding. The source

sends its data to the destination. In an MPLS domain, not all of the source traffic is

necessarily transported through the same path. Depending on the traffic characteristics,

different LSPs could be created for packets with different CoS requirements.

In Figure 1, LER1 is the ingress and LER4 is the egress router.

Figure 1. LSP Creation and Packet Forwarding though an MPLS Domain

Destination

LER2

LSR1 LER1

LER3

LSR3

LSR2

LER4

Label request

Label distribution

Data flow

E3E4 MPLS VPN Ver2 28.02.2008 3 of 7

Tunnelling in MPLS A unique feature of MPLS is that it can control the entire path of a packet without explicitly

specifying the intermediate routers. It does this by creating tunnels through the intermediary

routers that can span multiple segments. This concept is used for provisioning MPLS –

based VPNs.

MPLS Applications MPLS addresses today’s network backbone requirements effectively by providing a

standards-based solution that accomplishes the following: 1. Improves packet-forwarding performance in the network

2. MPLS enhances and simplifies packet forwarding through routers using Layer-2 switching

paradigms.

3. MPLS is simple which allows for easy implementation.

4. MPLS increases network performance because it enables routing by switching at wireline

speeds.

5. Supports QoS and CoS for service differentiation

6. MPLS uses traffic-engineered path setup and helps achieve service-level guarantees.

7. MPLS incorporates provisions for constraint-based and explicit path setup.

8. Supports network scalability

9. MPLS can be used to avoid the N2 overlay problem associated with meshed IP – ATM

networks.

10. Integrates IP and ATM in the network

11. MPLS provides a bridge between access IP and core ATM.

12. MPLS can reuse existing router/ATM switch hardware, effectively joining the two disparate

networks.

13. Builds interoperable networks

14. MPLS is a standards-based solution that achieves synergy between IP and ATM networks.

15. MPLS facilitates IP – over –synchronous optical network (SONET) integration in optical

switching.

16. MPLS helps build scalable VPNs with traffic-engineering capability.

MPLS VPN MPLS technology is being widely adopted by service providers worldwide to implement

VPNs to connect geographically separated customer sites. VPNs were originally introduced

to enable service providers to use common physical infrastructure to implement emulated

point-to-point links between customer sites. A customer network implemented with any

VPN technology would contain distinct regions under the customer's control called the

customer sites connected to each other via the service provider (SP) network. In traditional

router-based networks, different sites belonging to the same customer were connected to

each other using dedicated point-to-point links. The cost of implementation depended on

the number of customer sites to be connected with these dedicated links. A full mesh of

connected sites would consequently imply an exponential increase in the cost associated.

Frame Relay and ATM were the first technologies widely adopted to implement VPNs.

These networks consisted of various devices, belonging to either the customer or the service

provider, that were components of the VPN solution. Generically, the VPN realm would

consist of the following regions:

Customer network— Consisted of the routers at the various customer sites. The routers

connecting individual customers' sites to the service provider network were called customer

edge (CE) routers.

E3E4 MPLS VPN Ver2 28.02.2008 4 of 7

Provider network— Used by the service provider to offer dedicated point-to-point links

over infrastructure owned by the service provider. Service provider devices to which the CE

routers were directly attached were called provider edge (PE) routers. In addition, the

service provider network might consist of devices used for forwarding data in the SP

backbone called provider (P) routers.

Depending on the service provider's participation in customer routing, the VPN

implementations can be classified broadly into one of the following:

Overlay model

Peer-to-peer model

Overlay model 1. Service provider doesn’t participate in customers routing, only provides transport to

customer data using virtual point-to-point links. As a result, the service provider

would only provide customers with virtual circuit connectivity at Layer 2.

2. If the virtual circuit was permanent or available for use by the customer at all times,

it was called a permanent virtual circuit (PVC).

3. If the circuit was established by the provider on-demand, it was called a switched

virtual circuit (SVC).

4. The primary drawback of an Overlay model was the full mesh of virtual circuits

between all customer sites for optimal connectivity.

Overlay VPNs were initially implemented by the SP by providing either Layer 1 (physical

layer) connectivity or a Layer 2 transport circuit between customer sites. In the Layer 1

implementation, the SP would provide physical layer connectivity between customer sites,

and the customer was responsible for all other layers. In the Layer 2 implementation, the SP

was responsible for transportation of Layer 2 frames (or cells) between customer sites,

which was traditionally implemented using either Frame Relay or ATM switches as PE

devices. Therefore, the service provider was not aware of customer routing or routes. Later,

overlay VPNs were also implemented using VPN services over IP (Layer 3) with tunneling

protocols like L2TP, GRE, and IPSec to interconnect customer sites. In all cases, the SP

network was transparent to the customer, and the routing protocols were run directly

between customer routers.

Peer-to-peer model The peer-to-peer model was developed to overcome the drawbacks of the Overlay model

and provide customers with optimal data transport via the SP backbone. Hence, the service

provider would actively participate in customer routing. In the peer-to-peer model, routing

information is exchanged between the customer routers and the service provider routers,

and customer data is transported across the service provider's core, optimally. Customer

routing information is carried between routers in the provider network (P and PE routers)

and customer network (CE routers). The peer-to-peer model, consequently, does not require

the creation of virtual circuits. The CE routers exchange routes with the connected PE

routers in the SP domain. Customer routing information is propagated across the SP

backbone between PE and P routers and identifies the optimal path from one customer site

to another.

Dial VPN Service Mobile users of a corporate customer need to access their Corporate Network from remote

sites. Dial VPN service enables to provide secure remote access to the mobile users of the

Corporate. Dial VPN service, eliminates the burden of owning and maintaining remote

access servers, modems, and phone lines at the Corporate Customer side. Currently

accessible from PSTN (127233) & ISDN (27225) also from Broadband.

E3E4 MPLS VPN Ver2 28.02.2008 5 of 7

MPLS VPN Architecture and Terminology

In the MPLS VPN architecture, the edge routers carry customer routing information,

providing optimal routing for traffic belonging to the customer for inter-site traffic. The

MPLS-based VPN model also accommodates customers using overlapping address spaces,

unlike the traditional peer-to-peer model in which optimal routing of customer traffic

required the provider to assign IP addresses to each of its customers (or the customer to

implement NAT) to avoid overlapping address spaces. MPLS VPN is an implementation of

the peer-to-peer model; the MPLS VPN backbone and customer sites exchange Layer 3

customer routing information, and data is forwarded between customer sites using the

MPLS-enabled SP IP backbone.

The MPLS VPN domain, like the traditional VPN, consists of the customer network and the

provider network. The MPLS VPN model is very similar to the dedicated PE router model

in a peer-to-peer VPN implementation. However, instead of deploying a dedicated PE

router per customer, customer traffic is isolated on the same PE router that provides

connectivity into the service provider's network for multiple customers. The components of

an MPLS VPN shown in Figure are highlighted next.

Figure MPLS VPN Network Architecture

The main components of MPLS VPN architecture are:

Customer network, which is usually a customer-controlled domain consisting of devices

or routers spanning multiple sites belonging to the customer. In Figure, the customer

network for Customer A consists of the routers CE1-A and CE2-A along with devices in the

Customer A sites 1 and 2.

CE routers, which are routers in the customer network that interface with the service

provider network. In Figure , the CE routers for Customer A are CE1-A and CE2-A, and the

CE routers for Customer B are CE1-B and CE2-B. Provider network, which is the provider-

controlled domain consisting of provider edge and provider core routers that connect sites

belonging to the customer on a shared infrastructure. The provider network controls the

traffic routing between sites belonging to a customer along with customer traffic isolation.

In Figure, the provider network consists of the routers PE1, PE2, P1, P2, P3, and P4.

PE routers, which are routers in the provider network that interface or connect to the

customer edge routers in the customer network. PE1 and PE2 are the provider edge routers

in the MPLS VPN domain for customers A and B.

P routers, which are routers in the core of the provider network that interface with either

other provider core routers or provider edge routers. Routers P1, P2, P3, and P4 are the

provider routers.

E3E4 MPLS VPN Ver2 28.02.2008 6 of 7

Advantages of MPLS over other technologies BSNL's primary objectives in setting up the BGP/MPLS VPN network are:

1. Provide a diversified range of services (Layer 2, Layer 3 and Dial up VPNs) to meet the

requirements of the entire spectrum of customers from Small and Medium to Large

business enterprises and financial institutions.

2. Make the service very simple for customers to use even if they lack experience in IP

routing.

3. Make the service very scalable and flexible to facilitate large-scale deployment.

4. Provide a reliable and amenable service, offering SLA to customers.

5. Capable of meeting a wide range of customer requirements, including security, quality

of Service (QOS) and any-to-any connectivity.

6. Capable of offering fully managed services to customers.

7. Allow BSNL to introduce additional services such as bandwidth on demand etc over the

same network.

Tariff

Service 64

Kbps

128

Kbps

192

Kbps

256

Kbps

384

Kbps

512

Kbps

768

Kbps

1

Mbps

2

Mbps 8 Mbps

34

Mbps

45

Mbps

Gold 63000 105000 138000 178000 221000 301000 368000 423000 610000 2134000 3902000 4389000

Silver 52000 88000 116000 149000 185000 249000 306000 353000 487000 1706000 3119000 3509000

Bronze 43000 72000 95000 122000 162000 219000 267000 305000 355000 1242000 2272000 2556000

IP VPN 35000 60000 79000 102000 137000 186000 229000 263000 294000 1028000 1880000 2115000

1. Committed Data Rate in Bronze category - The bandwidth of Bronze category would be

restricted to 50% of bandwidth. However, the minimum B/W of 25% B/W will be

committed to Bronze customers

2. Discount on MPLS VPN ports - It has been decided to give multiple port discounts on

the total number of ports hired across the country as given below. It may be noted that

multiple ports are not required to be located in a city for offering this discount:

3. Discount Rates

No. of Ports Existed discount on VPN

Ports on Graded basis

Revised discount on VPN

Ports on Non-graded

basis

1 to 4 ports 0% 0%

5 to 25 ports 10% 5%

26 to 50 ports 15% 10%

51 to 100 ports 20% 10%

101 to 150 ports 20% 15%

More than 150 ports 20% 20%

4. Volume based discount on MPLS VPN Service - Annual volume based discount on

graded basis may be given to all customers as under:

Annual Revenue( in Rs.) on MPLS VPN

Service per annum Volume based Discount on Graded basis

Upto Rs.50 lakhs No discount

Rs.50 lakhs to 1 Crore 5%

Rs.1 Crore to 2 Crore 7.5%

Rs.2 Crore to 5 Crore 10%

More than Rs.5 Crore 15%

E3E4 MPLS VPN Ver2 28.02.2008 7 of 7

5. Shifting charges of MPLS VPN & IP VPN Port - Rs.2000/- per port.

6. Minimum hiring period for MPLS VPN and IP VPN ports - One year.

7. Upgradation of port to higher Bandwidth � No charges to be levied for up-gradation

to higher bandwidth. The rent for the lower BW port to be adjusted on pro-rata

basis.

8. Provision of last mile on R&G/ Special construction basis - The charges to be levied

as per prevalent R&G/ Special construction terms.

9. Local Lead charges: Included in Port Charges, if these are within Local Area of

Telephone system of a City/Town (Virtual Nodes).

10. All charges are exclusive of Service Tax.

Virtual Nodes

VPN Service based on MPLS technology was launched on 24th May 2003. The VPN

infrastructure consists of ten physical Point of Presence (POP) at Delhi, Kolkatta, Chennai,

Mumbai, Bangalore, Pune, Hyderabad, Ahemdabad, Lucknow and Ernakulem. These ten

POPs cater for the VPN requirement throughout India.

In view of competitive scenario, the cities where MLLN VMUX are existing were declared

as Virtual Nodes (For calculation of Local Lead Charges). There are currently 290 cities

declared as virtual nodes and also BSNL felt that flexibility towards dynamic expansion of

Virtual Nodes of MPLS VPN will help boost the customer base of MPLS VPN segment

hence the power to declare a city as a virtual node (condition MLLN VMUX should exist)

has been delegated to CGM vide letter no: No.112-3/2006-Comml Dated: 2nd April, 2007.

The charges (in addition to port charges) are to be calculated as below:

While Calculating the Leased Line charges for Connecting the VPN site to the

MPLS Node, the distance from the VPN site to the nearest MPLS Virtual Node or

MPLS Node, which ever is less, is only to be taken into account. This will be in

addition to the local Lead charges.

Section-4

Chapter-5

Metro Ethernet: Fiber based broadband Access

E3E4 Metro Ethernet Rev 2 28.2.2008 1 of 7

Equipping Metro Optical Networks to Deliver Ethernet Services

Ethernet services represent a significant growth opportunity for service providers and a potentially significant productivity gain for customers. Both parties are looking to Ethernet to meet the growing demand for higher bandwidth, lower operational expenses and better management and control.

To understand Ethernet services and revenues, you need to know the current positioning and where the market is headed. Like any new service offering Ethernet services are subject to a ‘life cycle’ of technology and implementation. This cycle can be broken down into three stages:

o An early stage—point-to-point solutions are sold to a limited number of larger customers or on-net customers. Leverages installed base of fiber.

o A middle stage—more complete point-to-multipoint service offerings are marketed to all customers both on-net and off-net, over fiber and copper. Service offerings still vary from one provider to another.

o A late stage—inter-provider compatibility exists and true multipoint-to-multipoint solutions are sold. Providers are delivering similar offerings, mainly differing on price.

Many providers today are in the early stage, delivering point-to-point Ethernet services over their existing network infrastructures to their ‘on-net’ customers where the carrier already has a fiber drop. However, in order for Ethernet services to fully mature and develop through the life cycle, there are a number of challenges and requirements that have to be overcome.

Two Viewpoints into the Ethernet Services Life Cycle

There are two viewpoints into this cycle – the viewpoint from the customer (services desired) and the viewpoint from the service provider (network capabilities). The best way to approach these viewpoints is to understand the needs of both the customer and the service provider, to understand the obstacles and then to understand how to fulfill these needs in terms of the network infrastructure and service offerings.

Customer Viewpoint: Ethernet Life Cycle and Services Desired

The service requirements desired by the customer are straightforward – speed, scalability, reliability and the type and number of services offered. As the services evolve from early stage to mid-stage, the demands from the customers also evolve, as discussed below and summarized in the following table.

Services Desired

Early Stage Mid-Stage Late Stage

Connections Simple point-to point

Multi-point Ubiquitous

Scope Small, within Metro

Metro, regional, some national /international

Available everywhere, true interprovider compatibility

Reliability Minimal, based on overbuild

Reliable but only on-net

Reliable

Ethernet Services Single service Multiple services Any service

Security Minimal Layered Multiple levels

But there are a number of challenges that must be overcome before customers are able move forward on widespread deployments. Making a change to an Ethernet-based network is rational only if certain criteria are met.


Cost Justifications

In early stage deployments, purchasing Ethernet services is usually driven by a single application where the economics and requirements outweigh the hassle of turning up a new service. This may be difficult to justify, especially for small to medium-sized businesses. Installation and provisioning charges for multiple locations, equipment replacement, new service level agreements and new management structures may drive the true cost of the service out of reach for many businesses.

More Bandwidth and Higher Speeds

Customers need to be able to determine what speeds are necessary to support their locations, which will differ in their requirements for bandwidth. The need to tag traffic with various priority levels will become critical. For example, deployments of VoIP require the ability to differentiate and prioritize traffic. Businesses are not willing to lose their voice calls simply because they have switched to a new network.

Local Management

Customers are asking for the ability to set and change various parameters on their networks. They would like to be able to provision circuits based on usage during peak times of the month - as well as during down times. They would like to be able to set priorities for applications when needed – without requiring intervention from the provider. In addition, customers would like to be able to monitor their billing charges.

Remote Locations

Finding consistent service offerings for remote locations is a major challenge facing customers in early and mid-stage deployments. While providers can probably justify network changes to support large customer locations, it may not be profitable to provide those same changes to smaller and more remote locations. Customers are looking for the same services at all ports, which may not be reasonable until later mid and late stage deployments.

Service Provider Viewpoint: Ethernet Life Cycle and Network Capabilities

The list of features and services offered by the provider varies greatly today, partly due to the position of Ethernet services in the current life cycle and partly due to the state of hardware and software available from vendors. Service providers must adapt their networks and offerings as the Ethernet Services life cycle continues to migrate from:

• the early stages, where it has been possible to adapt older equipment built for either the core or the Enterprise to fit specific needs

• to the middle stage where providers need purpose-built equipment that provides the necessary services, standards and cost points

• to the late stage where all equipment meets standards and interoperability requirements


Network Capabilities

Early Stage Mid-Stage Late Stage

Bandwidth management

Dedicated bandwidth through brute force (TDM)

Simple management through QoS/CoS

Powerful and distributed (using signaling)

Bandwidth granularity

Coarse/inflexible Better granularity, still a mix of TDM and Ethernet

Available everywhere, true interprovider compatibility

Network reach Based on fiber availability

Mix of fiber and copper

Any wire

Economics Business case proved in for large customers only

Business case proved in for medium and large customers only

Business case proved in for all customers

Network design Overlay architecture

Some convergence, some overlay, MPLS-oriented

True converged architecture

Equipment interoperability

Limited Some, based on vendor testing

Standards-based

Network interoperability

None Limited True interoperability

But before providers enter the Ethernet service market, they also need to examine and understand the variety of challenges associated with it.

Business Cases

Solid business cases must be developed before large scale Ethernet rollouts can take place. An attractive approach is to use solutions that enable low first cost on initial deployment, and that will scale as services and customers are added to the network.

Footprint – On-net versus Off-net

The majority of service providers maintain a network that reaches most of their customers’ locations directly (on-net). Providers also need ways to economically reach all of their customers’ locations, including those not currently on their network (off-net). Going forward, providers must be able to use any mix of fiber or copper to deliver Ethernet services, and they must be able to use these wires without requiring major changes to the core transport infrastructure. Providers also need the ability to provide all services over a single access network and reduce dependence on LEC access lines to reach ‘off-net’ customers.

Deployed Infrastructure Designed to Support Circuit Switching

Another challenge facing providers is maximizing the use of their deployed infrastructure. Providers need to maximize the use of currently deployed infrastructures (both fiber and copper) to support existing legacy TDM services and new Ethernet-based services. Providers must be able to maintain critical circuit-based revenue streams while supporting the rollout of new high-performance Ethernet-based services, and those Ethernet services and features need to be identical at any and all locations.


OAM&P with Multiple Vendors

Providers must coordinate Operations, Administration, Management, and Provisioning (OAM&P) among equipment from multiple vendors using standards-based solutions.

Bandwidth Management

Rather than be forced into strict bandwidth guidelines or use unlimited bandwidth to solve traffic issues, providers are looking for the ability to manage bandwidth gracefully through the use of management tools such as rate limiters, policers, Quality of Service (QoS) and Class of Service (CoS).

Service Level Agreements

Both providers and customers believe that service level agreements (SLAs) and service level management (SLM) are necessary for successful relationships. Before deploying wide-spread Ethernet services, providers need to be able to support expected levels of network reliability to ensure compliance with subscriber service level agreements (SLAs).

Schematic of General PON (Passive Optic Network)


Proposed Services on BSNL FTTH network The first and foremost service proposed in the deployment of these PON technologies is to roll out the Next Generation Play Network (NGPN). Ethernet Private Leased Lines ( EPL), Ethernet Private LAN service ( EP-LAN) to the customers requiring the high bandwidth. Today Ethernet is the most popular medium used by the most of the customers in their Local Area Networks ( LAN). In addition Ethernet, being the most common and interoperable protocol, is being used extensively in all the computer – communication products. Hence Ethernet access service shall be the one of the popular service in the current days of computer communication. The regular TDM leased lines give away to this Ethernet access service.

EPLs are the point to point leased lines extending the Ethernet transparently and securely between the two customer sites. The Ethernet Private LAN service can be offered in the Point to Multipoint method ( Hub-Spoke ) or Multipoint to Multipoint ( Local Area Network ) method. EPLAN can be offered to customer as Wide Area Network ( WAN ) service. Apart from bigger bandwidth requirements, some of the high end customers require carrier class reliability upto their premises. These PON technologies shall be one of the ultimate technologies that delivers both high bandwidth and high reliability. The fibre redundancy upto the customer premises ensures this reliability.

It shall be easier to sign the Service Level Agreements ( SLA) with the customers using the PON technologies. These PON technologies shall permit management of the customer premises equipment ( Optical Network Terminals – ONTs ). End to end provisioning feature on PONs enable the service provider to dynamically manage the customer needs. The second important service proposed to offered to customers is Next Generation Broadband Service. This PON technology can also be used to deliver Broadband service to the customers in the Technically Non Feasible ( TNF ) areas. Normally the 2 Mb/s ADSL broadband connection works upto 4Kms. The 2Mb/s and other high speed Broadband connections needs to deploy either VDSL or alternate medium connection such as wireless. Higher bandwidths for broadband connections can be delivered to the customers as remote as 20 Kms from the Exchange premises with the PON technologies. PON technology allows the service provider to share the fiber cost of running fiber from the CO to the premises among many users—usually up to 32 locations. Since multiple customers use the single fibre infrastructure, the cost of the service roll-out shall be lower than for the fibre provisioning for the individual customer. Thus customers can be offered the broadband service in the entire operational area of BSNL network. The third service that can be proposed is the voice service ( TDM or IP), i.e. extension of PSTN lines to the customers. In GPON, this service can be extended using the 64 Kb/s TDM lines from exchange to customer. Alternately to cover a group of customers, we may use V 5.2 interface to extend the voice service to the customer premises. In case of GE-PON (Gigabit Ethernet PON)


the voice service can be extended to the using Voice Over Internet Protocol ( VOIP). From the BSNL network point of view GPON, being the TDM based technology, shall integrate into the existing switching network. While the VOIP feature in the GE-PON provides easy migration path to the Next Generation Network ( NGN ) of the BSNL. Since TDM switches and the NGN are to coexist for upto 2015 as per the NGN vision plan both GPON and GE-PON are the most suitable PON technologies for BSNL. The video service ( Radio Frequency - RF or IP), which is one of the triple play services, is the fourth service proposed to be extended to the customer. GE-PON offer 1.25 Gb/s capable Gigabit connectivity upto the customer premises.

Both GPON and GE-PON can also roll-out broadcast Cable TV services using the third wavelength at 1550 nm using RF-video. This third wavelength

a. GPON: GPON supports two methods of encapsulation: the ATM and GPON encapsulation method (GEM). The ATM method is an evolution of existing APON/BPON standards, and all voice, video, and data traffic is encapsulated at the customer premises for transport back to the CO. With GEM, all traffic is mapped across the GPON network using a variant of SONET/SDH generic framing procedure (GFP). GEM supports a native transport of voice, video, and data without an added ATM or IP encapsulation layer. GPONs support downstream rates as high as 2.5 Gbits/sec and upstream rates from 155 Mbits/sec to 2.5 Gbits/sec. BSNL is procuring the GPON that will support downstream rate 2.5Gbps and upstream 1.25 Gbps.

b. EPON: As with standard Gigabit Ethernet, EPON has a nominal bit rate of 1250 Mbps, using 8B/10B encoding. It is defined as a single fiber network using Wavelength Division Multiplexing (WDM) operating at a wavelength of 1490 nm downstream and 1310 nm upstream. This leaves the 1550 nm window open for other services, such as analog video or private WDM circuits. EPON Physical media Dependent (PMD) choices will include short reach optics with a range of 10 km and a 1:32 split ratio, and long reach optics with a range of 20 km and a 1:32 split ratio. Ideally, this will allow for interoperability and intermixing of different PMD types enabling a wide range of split ratios and distances. Low-cost Gigabit EPON transceivers using Distributed Feedback (DFB) or Fabry-Perot lasers and high sensitivity APD and PIN detectors are available. This is important, as optical transceivers have historically been the highest cost component in a PON network.


Fibre Infrastructure As per the transmission media guidelines announced in the past, Overlay Access Network is to be planned in all the District Head Quarters. High Count Fibres ( 96F/288F ), Multiple PLB pipes and FDMS are deployed in the Overlay Access Network. OAN aims at creating Optical fibre infrastructure for supporting all the network elements (RSU/RLC/DLC/GSM/WLL/LMDS/Leased lines/NIB) and the customers. It may be observed that all the network elements being deployed in the network including the routers, LAN Switches require the Dark fibre. 1. Apart from this NIB 2.2 project is being executed in 248 cities. This year the broadband group has proposed to increase the number of cities to 315. Dark fibre is required for the DSLAMs to the Ethernet Switches in all these cities. Number of DSLAMs shall increase over the years also. 2. GSM network is also growing with the execution of Phase-V+ and with the 60,000 sites are planned by the CMTS group for this project. 3. Broadband DLCs are also planned. These B-DLCs also require the Optical fibre cable. 4. Fibre needs to be provided for very important customers also for providing leased lines. 5. Apart from this all the new evolving technologies and customer demands, and new services require high speed connectivity to the customer. Thus requirement Optical Fibre in the Exchange Area becomes the important for the Telecom Carrier. The project circles are executing the Fibre To The Curb ( FTTC ) project alternately known as Overlay Access Network. As soon as the customer requirement is available the fibre laying from the nearest Manhole ( Fibre Access Point ) to the customer is completed and the service provisioning is done quickly.

Section-V

Chapter-1

BSNL Application Packages

E3E4 BSNL Application Packages, Ver1 14.12.2007 1 of 12

DOTSOFT

1.0 DOTSOFT is an Integrated Telecom Database System comprising of :-

• Commercial

• TRA (Billing & Accounting)

• Directory Enquiry

• Fault Repair Service

• Running on a Wide Area Network

2.0 INTRODUCTION

• DOTSOFT is an integrated telecom database system comprising commercial,

billing, accounting, fault repair service and directory enquiry services

• It can run not only on a wide area network (WAN) spanning an entire district

but also on a local LAN in the offline mode.

• DOTSOFT is based on the latest software technologies running on a WAN

and is the first of its kind in BSNL in the field of information technology.

• It has been conceptualised, designed and developed entirely by the core group

of the Software Development Centre of the Andhra Pradesh Telecom Circle,

Hyderabad.

• It has been successfully implemented in all the districts in AP Circle. It has

been also successfully implemented in many circles in BSNL.

2.1 Concise description of DOTSOFT

• DOTSOFT is an enterprise wide telecom database system that revolutionizes

the operation and supervision of customer services by enabling all the

personnel to work online.

• The central server contains the complete database to which all the nodes

anywhere in the district log in. The database is accessed using application

software residing in the nodes which have GUI interface.

• The nodes in the customer service centre service all the subscriber requests

which flow to the commercial and accounts sections as the case may be.

• After validation and approval from the the concerned sections the work orders

flow to the different field units depending on the activity

• After the completion of the work orders the commercial and billing data of the

subscriber gets updated.

• Bill generation is absolutely easy and totally secure.

• Payments are faster and completely hassle free for the customer and the

counter personnel because of the use of bill scanners.

• Revenue accounting and ledger reports are available immediately at the end of

the month.

• The system can generate any kind of detailed as well as statistical reports.

• Online enquiry is available for supervision and queries


2.2 IMPORTANT FEATURES OF DOTSOFT

• Every subscriber is identified by an identification number which shall be

unique all over the country (CCCSSAYYYYMMXXXXX).

• All-India shift and closure cases are processed immediately.

• Database security is implemented through database grants and dynamically

changing menus.

• System is highly scalable and can run on a wide variety of operating system

platforms.

• The system can run on both client-server or host based systems or web based

intranet without any change in the software.

• All the parameters of the system are table driven.

• State of the art technology used in the designing of the wide area network.

• Central control of the WAN using a robust network management software

2.3 UTILITY OF DOTSOFT

• DOTSOFT is one of the first steps towards the bold and ultimate goal of E-

Governance and paperless offices.

• All the work is done online which results in excellent customer service, non

duplication of work, total supervision, complete transparency, better planning

and with a facility of instant reports.

• Single window concept introduced for the first time.

• Concept of request registration number introduced through which the status of

the request can be tracked and inquired.

• Signature warehousing to be included for online verification purpose.

• Instant electronic flow of data between the offices and field units with facility

to print wherever required.

• Various intimation letters to subscribers automatically generated.

• Priority execution of advice notes.

• Messaging system between CO and Field units.

• DOTSOFT mail system between all users.

• Complete history of subscriber’s activities available online.

• Details of subscriber records & requests, bills, demand notes,

wait list, payments and work orders available online.

• Variable billing cycle, ISDN billing.

• Centrex and WLL billing U/D.

• NPC advice notes once completed online are billed in the next schedule.

• Un-addressed bills are generated when a DEL is working but the NPC advice

note has not been completed in the system.

• Finalization of closed connections are settled immediately and a summary of

outstanding OR refund order is generated.

• Uncollected deposits can be billed in the regular bills and the accounting is

taken care of automatically.


• Supplementary bills can be issued for any uncovered amount.

• Outstanding details can be taken for any month on any given date.

• Debit charges and credits generated by the system and hence remove any

requirement of manual entry.

• Voluntary deposits incorporated.

• Outstanding surcharge if any, will be transferred to the next bill, which

reduces the number of outstanding bills.

• Automatic generation of ringing/disconnection list, which can be ported to an

interactive voice response system to alert the subscriber.

• Directory Enquiry shows the status at the moment of enquiry. It can query on

any of the subscriber’s details in part or in full.

• Complete managerial supervision is possible about the activities happening

anywhere in the district.

• Statistical data is generated to find out activity, usage and payment patterns to

facilitate better customer service.

• Online help facility covering all rules and regulations is provided.

• User manual is provided in the .html format.

2.4 Security features in DOTSOFT

• Blocking of User access to DOTSOFT menu if user password violating

password rules.

• Allotment of Dynamic Roles at the time of login through DOTSOFT Menu as

a security measure (Blocking of SQL ACCESS to DOTSOFT MENU users

and all DOTSOFT Modules will work only through DOTSOFT Menu.)

• Blocking of user access from unauthorized IP address.

• Restricting SQL access with product user profile.

• Provision for profile creation/allotment.

• Enabling log in triggers to block unauthorized module Developers other than

DBA.

• Designed security policy for oracle DBMS and placed on DOTSOFT site.





BSNL HR Package

1.0 About HR Package

It is an in-house package developed by the employees of BSNL for usage by

BSNL. The design and development of the package started initially at Telecom

Factory as a part of their effort of internal computerization, and the Employee

master was developed. Since the HR requirements of all the employees of BSNL

are more or less same, the same package was adopted for entire BSNL and the

development was taken over by IT Project Circle. The initial development was

done in Forms and was launched for a trial run at Maharashtra circle, Kolhapur

SSA and Telecom Factory Mumbai.

Since the Forms are heavy for deployment over a network, the development at

ITPC was continued in PHP/JAVA, and even the initial development was

converted and was launched on All-India Level on 16th

Aug 2005.

The further development is continuing at ITPC, to cover all other areas of HR,

like transfers, promotions, training, quarter allotment, leaves, attendance, medical

schemes, nominations and Pay Roll.

2.0 Platforms used

OS --- Linux

Data Base --- Oracle 9i/10g

Application Server --- 9iAS/ 10g AS

Front end --- JAVA/ PHP

3.0 Who can access the package?

All the employees are envisaged to be the users of the package ultimately as all

the leaves, all the advances and other personal claims are proposed to be applied

on-line by the employee for sanction and payment on line. A provision is made

for the supervisor of the employee to make all these applications on behalf of the

illiterate sub ordinate employees.

The transactions on the package are to be done only by the authorized users.An

employee with a system generated staff number, generated by the system on

entering certain mandatory data of an employee, only can be made an authorized

user. Go through the instructions on links below to know more about this.

After the staff number is generated, the employee can be made as a user by the

concerned SA (System Administrator). The employee will be given as the user


name( the employees’ staff no.) and a pass word initially. But on first log on the,

system will force the change of pass word by the user. The user name can not be

changed. Please note that the changed pass word is case sensitive.

4.0 How to access the package?

The authorized user has to log into intranet site, and click the HR Package link

available there in. This activity opens a page asking options for the type of

network connection used, ie. either MPLS VPN or an internet connection. This

page also has one other link for getting the details about HR Package, and

another link for sending a request for issue of user name and pass words or any

other clarification.

Choosing and clicking the appropriate option will open the log in page of the HR

Package. The user name and password for HR package will allow the bonafide

user to access the HR package.

Creating the system administrators and Use of One – Time User Name and Pass

Word by the System Administrator

1. The SA has to be created for each of the main offices ie the corporate office,

circles and SSAs.

A One Time user name and password for the SA will be mailed to mail address of

the SA or to the address from which the request is received.

Using this One Time details, the HR package can be accessed. The system will open

the employee master page to the SA.

The SA will have to enter his details in the staff master and submit the page. The

system will generate a new staff no. for the SA. The system will also make the SA as

a user automatically with the newly generated staff no. as the username and

password.

Only on the generation of the new staff no., the one time user name and pass word

will become invalid. If the staff no. is not generated for any reason, the one time UN

& PW will continue to be valid.

The SA can log in with his new staff no. as the user name and pass word and will be

forced by the system to change the PW on first log in.

There after the SA can enter the details of any no. of employees and generate new

staff nos. for them. He can also make them the USERS for data entry purpose. The

initial user name and pass word for the employee will be will be the staff no. of the

employee generated by the system and the pass word will have to be changed by the

user on first log in.


5.0 Concept of the Location (Based on organizational structure, address and the type

of service provided by the office concerned)

Through the LOCATION we are trying to define the organizational structure of

BSNL. Organization helps in governance at each level by way of decentralization.

Organisational structure is the most important part of the BSNL, in fact, for any

organization. Generally organizations are defined in different layers depending on

the functions to be carried out. The reporting/relational structure between the

layers also is well defined. The layers can one below the other, one parallel to the

other, or any other way as the organization defines.

Each layer of the organization is manned by certain number of employees. The

reporting structure among the employees in a layer also well defined by way of

grades in which the employee is placed. Hence organizational structure has no

relation with the grades and the number of the employees in that layer of the

organization. The number of employees and the grades of those employees in

each layer depends on the functionality, responsibility and other parameters

assigned to the layer by the organization.

As many posts, in different grades, as may be required are created in each

location for discharging the assigned work.

Traditionally BSNL (DOT) was having the following structure.

a). DOT(Ministry) ---- analogous to the Corporate Office of BSNL (Ministry

remains today also but as far as the BSNL is concerned , Ministry is not a part of

its’ structure).

This was/ is the top most layer. (Headed by DG/ CMD )

b). Circles ---- There are many Circles and are discharging different functions

like, Territorial and Metro Districts for telecom operations , Project Crcles,

Maintenance Regions, Production, QA, T&D, Training, Civil Wing, Electrical

Wing, Architectural Wings etc.

Names of all the circles are already entered in the system.

This is the second layer. (Headed by CGM). They normally report to the

Corporate Office

c). SSA ---- This layer came into the being in 1980s. Earlier there were Divisions

, Sub- Divisions.( They still exist).

Names of all the SSAs for the relevant circles are already entered in the system.


This is the third layer. ( It is headed by officer in an appropriate grade).

We had, in the past, a defined structure at next levels called Divisions and Sub-

Divisions under the Circles before SSAs came into being. But after SSAs came

into being, the structure under each SSA has been different to suit its’ needs.

There is a general similarity in all the structures below the SSA, but it is not the

same for all the SSAs.

The corporate office, the circles, the SSAs are referred to as main offices – only

for the purpose of understanding the location concept.

d). Units ----

Units are to be created by the Sys. Admn. of the relevant main office. Before

creating the units in the system it is highly recommended that the structure is

made on the paper and after confirming the correctness, the same may be entered

in the system.

Unit is defined based on the following.

a) Name the unit

b) Address of the unit --- postal address

c) Service rendered by the unit --- operation, civil, electrical, production etc.

5.1 Each of the main offices i.e. Corporate office, Circle, SSA can have units under

them based on the above criterion. For eg.

a) BSNL corporate office has its office at Statesman building.— If some of the

employees in the corporate office are located at Sanchar Bhavan and at other

addresses like Jan path hotel, then Sanchar Bhavan will be one of the units of the

Corporate office and Jan path hotel will be another unit of the corporate office.

Here name of the office is same but the address is different.

b) Maharashtra Circle has its’ office at Fountain building, and another office at Juhu

in Mumbai. Juhu office will be a unit under Maharashtra circle.

c) There are number of circles which do not have SSAs under them like QA, T&D,

TFs etc. Each office under their direct control will be a separate unit and one unit

can be reporting to the parent office or to another unit of the parent unit. For eg.

i) QA circle has its main office at Bangalore. There are many offices in

India which are directly reporting to QA office at Bangalore. Each will

be a unit, say unit 1 at Mumbai, unit 2 at Kolkatta with reporting office

as Circle office.

ii) There are many other offices of QA like QA of TF Mumbai ,QA of

Pune say unit 3, unit 4 respectively which report to unit 1 of QA

iii) This process will continue till all the offices of QA are covered.


iv) Same procedure will be followed in all the main offices.

v) In case of civil wing, electrical wing, etc. the reporting structure has to

be defined. If the civil wing is reporting to the circle office/SSA then it

will be treated as a unit of the circle/SSA. If the civil wing is a treated

as a separate circle, then a separate civil circle has to be created and all

the offices reporting to the civil circle will be treated as units of this

civil structure with service type as civil. Same logic is applicable to

electrical wing with electrical as the service type and to Telecom

Factories with service type as production.

d) Service type is defined as Operation for all telecom circles including CMTS, QA,

T&D etc.; training for training institutes; production for Telecom Factories etc.

PLEASE NOTE THAT THE LEVEL OFFICER HEADING THE LOCATION IS NOT AT

ALL MENTIONED IN THE ABOVE DISCUSSION

.

Each of the main offices and each of the units is known as a location and the existing

BSNL structure is mapped into the package.

Every employee is assigned to a location in the structure. By doing so the details of the

employee relating to the office in which he/she is working, the address of the office and

the service he/she is rendering to BSNL are identified. For eg.

-if we ask an employee where he/she is working – the reply would be that I am

working in the Juhu office of Maharashtra circle, rendering the service of Telecom

operations to BSNL.

Whenever a new office is created, say for eg. a new circle is created like UP(E), then a

new location has to be created and employees have to be reallocated to the new

office/unit. Even if a new building is to be used, a new location in the form of a new unit

has to be created and employees have to reallocated to it.

The reallocation can be done through the transfer module, which will be taking some

time to be introduced till such a time the changes have to be done manually.

SA for the UNITS created by the respective SA of the main office.

As and when a new unit is created, the system, by default creates and inserts a ONE –

TIME user name and PW for that unit. The format for both of them is “Short Description

of the unit _ TRG”. For eg if a unit of QA is created in Pune with short description as

“QA_PUNE” then both the one time UN & PW for this unit will be

“QA_PUNE_TRG”.

This can be given to any employee of QA Pune for following the above instructions.

While creating a SA of a unit, the level of the officers have to be kept in view, as

prescribed in BSNL instructions.


Using this one time user name and password, the same procedure as above for creating

the SA will have to be followed for creating users in the units.

The data entry into the employee master will be only in capitals. System automatically

does it. So the one time PW & UN are in capitals only. But the changed PW by the

user on first log in is case sensitive.

System requirements at the users’ end

The package can be best operated on any computer with the following configuration..

1. Pentium P-III or above version.

2. Widows 98, XP, 2000, but not the server versions

3. Minimum 128 MB RAM

4. Best viewed in Internet explorer-6 or above.

5. Network connectivity.

6. Pop ups should not be blocked.

Section-V

Chapter-2

NOS & RDBMS

E3E4 NOS & RDBMS, Ver1 14.12.2007 1 of 4

Network Operating System

Operating System

An operating system (OS) is the software that manages the sharing of the resources of a

computer. An operating system processes raw system data and user input, and responds by

allocating and managing tasks and internal system resources as a service to users and programs of the

system. At the foundation of all system software, an operating system performs basic tasks

such as controlling and allocating memory, prioritizing system requests, controlling input and

output devices, facilitating networking and managing file systems. Most operating systems come

with an application that provides a user interface for managing the operating system, such as a

command line interpreter or graphical user interface. The operating system forms a platform for

other system software and for application software. Mac OS, Windows, and Linux are some of the

most popular OSes.

Network Operating System

Network Operating System (NOS) is an operating system that includes special functions for

connecting computers and devices into a local-area network (LAN) or Inter-networking. Some

popular NOSs for DOS and Windows systems include Novell Netware, Windows NT, 2000,

2003, RHEL, IBM AIX and Sun Solaris etc.. The Cisco IOS (Internet Operating System) is also

a Network Operating System with a focus on the Internetworking capabilities of network devices. A NOS controls a network and its message (e.g. packet) traffic and queues, controls access by

multiple users to network resources such as files, and provides for certain administrative functions,

including security. A network operating system is most frequently used with local area networks and

wide area networks, but could also have application to larger network systems. The upper 5 layers

of the OSI Reference Model provide the foundation upon which many network operating

systems are based.

Features of NOS Some of the features of Network Operating System are:

• Provide basic operating system features such as support for processors, protocols,

automatic hardware detection and support multi-processing of applications.

• Security features such as authentication, authorization, logon restrictions and access

control

• Provide name and directory services

• Provide file, print, web services, back-up and replication services

• Support Internetworking such as routing and WAN ports

• User management and support for logon and logoff, remote access; system management,

administration and auditing tools with graphic interfaces

Services offered by NOS Network services are the foundation of a networked computing environment. Generally

network services are installed on one or more servers to provide shared resources to client

computers. Network services are configured on corporate LAN’s to ensure security and user friendly

operation. They help the LAN run smoothly and efficiently.


Authentication Service Authentication service provides authentication service to users or other systems.

Users and other servers authenticate to such a server, and receive cryptographic tickets. These

tickets are then exchanged with one another to verify identity. Authentication is used as

the basis for authorization, privacy, and non-repudiation. The major authentication algorithms

utilized are passwords, Kerberos, and public key encryption.

Directory Service

A directory service (DS) is a software application that stores and organizes information about a

computer network's users and network resources, and that allows network administrators to manage

users' access to the resources. Additionally, directory services act as an abstraction layer between

users and shared resources.

DHCP Service

The Dynamic Host Configuration Protocol (DHCP) is a set of rules used by communications

devices such as a computer, router or network adapter to allow the device to request and obtain an IP

address from a server which has a list of addresses available for assignment. DHCP is a protocol used

by networked computers (clients) to obtain IP addresses and other parameters such as the default

gateway, subnet mask, and IP addresses of DNS servers from a DHCP server. The DHCP server

ensures that all IP addresses are unique, Thus IP address pool management is done by the server.

DNS Domain Name System is used for transalating human readable names for machines (Servers,

Domains, Clients) to IP addresses and vice versa. It also stores other information such as the list

of mail exchange servers that accept email for a given domain. In providing a worldwide

keyword-based redirection service, the Domain Name System is an essential component of

contemporary Internet use.

e-Mail Service Electronic mail is a store and forward method of composing, sending, storing, and receiving

messages over electronic communication systems. The term "e-mail" applies both to the Internet e-

mail system based on the Simple Mail Transfer Protocol (SMTP) and to intranet systems allowing

users within one organization to e-mail each other. Often these workgroup collaboration

organizations may use the Internet protocols for internal e-mail service.

Network Print Service Print service is a facility that is extended to the users so that printer service is available

to all users through the network and no individual printer is required on the client machine.

Network File Service network file system is any computer file system that supports sharing of files, printers and other

resources as persistent storage over a computer network. The Network File System (NFS) which

became the first widely used distributed file system. Other notable distributed file systems are

Andrew File System (AFS) and Server Message Block SMB, also known as CIFS


RDBMS

Short for relational database management system and pronounced as separate letters, a type of

database management system (DBMS) that stores data in the form of related tables. Relational

databases are powerful because they require few assumptions about how data is related or how it

will be extracted from the database. As a result, the same database can be viewed in many

different ways. An important feature of relational systems is that a single database can be spread

across several tables. This differs from flat-file databases, in which each database is self-

contained in a single table. Almost all full-scale database systems are RDBMS's. Small database

systems, however, use other designs that provide less flexibility in posing queries.

Database

� A group of ‘tables’ with related data in them is called a Database

� Coherent collection of data with some inherent meaning, designed, built and populated

for a specific purpose.

DBMS and RDBMS � Software designed to manage data in database is DBMS.

� In relational databases, data is organised into tables and tables are closely related.

Designing Relational Database � Analyze the situation to gather information about the purpose.

� Decide on columns, data types and the lengths of data.

� Create the database and tables.

� Populate the tables

Normalizing the Data

� Normalizing is the process of organizing data into related tables.

� Purpose - Eliminate Redundant Data

Rules for Normalizing

� FNF

� Columns can’t contain multiple values

� SNF

� Every non-key column must depend upon the entire key and not just a part of primary

key.

� TNF

� All non-key elements must not depend upon any other non-key columns

Relational Database Objects � Tables

� Columns

� Data types

� Stored Procedures

� Functions

� Triggers

� Views

� Indexes


Concept of Keys � Primary Keys – to enforce uniqueness and Not-NULL among the rows

� Foreign Keys – are one or more columns that reference the primary keys or unique

constraints of other table.

� Constraints are server-based system implemented data integrity enforcement

mechanism.

� Rules/checks

Managing Data Integrity Data integrity means data in a database adheres to business rules

� Application Code

� Database triggers

� Declarative Integrity constraints

Database triggers: Programs that are executed when an event, such as insert or

update on a column, occurs in a table.

Types of Constraints

� NOT NULL

� UNIQUE

� PRIMARY KEY

� FOREIGN KEY

� CHECK

Concept of Schema A schema is a logical grouping of database objects based on the user who owns them

SQL

� IBM invented SEQUEL(structured English query language) for data queries

� Over the data it has been added now it can not only query but fully build and manage

databases

� SQL sentences are

� DDL (data definition language)

� DML (data manipulation language)

� DCL (data control language)

Processing of SQL statement � SQL statement is received as strings and broken into – Oracle verbs and oracle objects

� Oracle verbs are then compared with verbs available in Pursing Tree (appropriate and

correct position check)

� Then check for availability of Database objects(refers data dictionary)

� Check for permissions to the user who has fired the statement (refers data dictionary)

� Opening of Cursor(area where data is to stored)

Steps of SQL statement Processing 1.Open the area in memory and maintain a pointer to that location

2.Parse the SQL statement

3.Bind the select list columns to the cursor columns

4.Define variables to fetch the data from the cursor variables

5.Execute the query

6.Fetch data one row at a time

7.Perform required processing

8.Close the opened cursor

Section-V

Chapter-3

IT Security

E2E3 IT Security, Ver2 28.02.2008 1 of 3

“Information Security ABSTRACT

In the age of Information Revolution, the management of information and its

security is the key concern for all organisations and nations. For sharing of

information among the intended users, the systems have to be networked. With this

networking the risk of unauthorized use and attacks have taken major attention of

Managers.

Networks and Information are subject to various types of attacks and various

products are available in the market for securing the systems. But it needs the

thorough understanding of the various issues involved and proper implementation.

Need of Securing Information

Information is most important asset for any organization especially for a telecom

operator. All our revenue comes from some information only. Besides revenue if there is

loss of information all our processes can come to a stand still and it will result in

interruptions. It takes lot of efforts to build up information, but the small negligence at

any level can result in loss of information. The good aspect of information is that now it

is easy to move and easy to alter and this aspect has added insecurity dimension to

information during security incidents besides revenue, the image of the company is also

at stake.

So it a high time that we have a security policy endorsed by the higher management and

get it implemented. Implementation of security policy is just not putting up data security

devices and having a tight access control mechanism, it is an on going process. The

security mechanism is to be continued reviewed against the failures and new threats and

risks. The risks are to be analyzed and managed accordingly. The management of risk

involves its acceptance, mitigation or transfer. The most important aspect is to have a

security organizational set up which will do all these activities.

Information Security ensures

• Availability,

• Integrity and

• Confidentially of information The information security set-up of any organisation has to think of security of

individuals and file-level data objects and to protect the network from being launching

pad of attacks by hackers. The general solution to security design problems lies in

‘authentication’ and ‘authorisation’ model, which is collectively known as access control.

However access control does not provide enough security because it ignores the potential

threat from insiders. Accountability steps in where access control leaves off.

A lot can be observed by just watching. Pay attention to what you can see and measure.

How is it to be done? Answer lies in intercepting all transactions that involve files. Think

of it as event detection. The event records are filtered and correlated at the time of


capture to distinguish between OS and application activities from user-initiated data use.

The audit trail is to be compressed and made temper proof and archived. Because this

capture occurs in real time, the reaction can be in real time. The reaction should be risk-

appropriate and may range from issuing an alarm to change in authorisation policy. The

point is that you should have the event log and monitor it.

Various Types of Attacks and their Counter Measures Security Incidents are mainly due to:

• Malicious Code Attacks

• Known Vulnerabilities

• Configuration Errors

Indications of Infection

A system infected with malicious codes will have following symptom(s): 1. Poor System Performance

2. Abnormal System Behavior

3. Unknown Services are running

4. Crashing of Applications

5. Change in file extension or contents

6. Hard Disk is Busy

There can be various types of malicious codes like Virus, Worms, Trojan Horses, Bots,

Key Loggers, Spyware, Adware etc. The solution against these is to have good anti-virus

software. The anti-virus software should be updated in routine so that it is effective

against new malicious codes.

The Configurations of the systems are Vulnerable because of

1. Default Accounts

2. Default Passwords

3. Un-necessary Services

4. Remote Access

5. Logging and Audit Disabled

6. Access Controls on Files

Monitoring Security of Network

� Monitor for any changes in Configuration of ‘High risk’ Devices

� Monitor Failed Login Attempts, Unusual Traffic, Changes to the Firewall, Access

Grants tom Firewall, Connection setups through Firewalls

� Monitor Server Logs

Security has to implemented at all levels i.e. Network, NOS, Application and

RDBMS.

Security of Network

Firewalls are used for Perimeter Defence of Networks. Using Firewall Access Control

Policy is implemented. It controls all internal and external traffic.


Security of OS/NOS

Keep up-to-date Security Patches and update releases for OS

Install up-to-date Antivirus Software

Harden OS by turning off unnecessary clients, Services and features

Security of Application

Keep up-to-date Security Patches and update releases for Application Package

Don’t Install Programs of unknown origin

Precautions with Emails

Protection from Phishing attacks

Securing Web Browsers

Security of RDBMS For securing data the following are needed:

1. User Management

2. Password Management

3. Managing Allocation of Resources to Users

4. Backup and Recovery

5. Auditing

Summary of Action Items

1. Secure Physical Access

2. Remove Unnecessary Services

3. Secure Perimeter

4. Properly Administer Network

5. Apply Patches in Time

6. Install Antivirus Software

7. Backup Data

8. Encrypt Sensitive Data

9. Install IDS

10. Proper Monitoring

Conclusion:

Caution is the word when it comes to Information Security. In an era, when information

is the power and wealth for an organisation, one cannot expect taking chances with it.

Therefore, it is advisable not only to secure the physical access to the information, but

also to install antivirus software, wherever required. ‘Prevention is better than cure’- goes

strong in case of Information Security also, if we want to create competitiveness.

Moreover Security is a continuous process, the preparedness of yesterday may not be

sufficient for today. We have to review periodically to find the gaps and immediate

action.

GSM BSNL Training Part2

Documents

transmission overview

mode of examination

dwdm measurements

overview of cdma technology

ngn bsnl plans

telecom wing of bsnl

training of officers

unsuccessful executives