Final Report BSNL2

ACKNOWLEDGEMENT

It is with profound gratitude that I express my deep indebtedness

to all departmental heads of BSNL-JAIPUR, without their support and

guidance it would not have been possible for this training to have

materialized and taken a concrete shape.

I owe a personal thanks to my training in charges- Mr. Surinder

kumar (S.D.O.P-II BSNL) and Mr. S.S.GAHLOT (P.M BSNL) who

extended full support and cooperation at every stage of my training

period.

I would also like to take this opportunity to acknowledge the

guidance and support from MR. NERAJ SHRIVASTAV, H.O.D. for

undergoing training at a reputed company like B.S.N.L.

I am indebted to my parents and friends for their constant

encouragement and helping me in my endeavor. Last, but not the least, I

would like to thank everyone who has contributed for successful

completion of my training.

MUKESH KUMAR

PREFACE

Organizations are made up of people and function through people.

Without people, organizations cannot exist. The resources of men, money,

material, machinery, and mechanism are connected, coordinated and

utilized through people. It is the effectiveness of the human system that

differentiates successful organizations from the unsuccessful one.

Engineers need to concentrate more on mechanism and the way in which

things have been made.

The need of training arises for doing things yourself,

understanding its way. Practical exposure for doing things makes a

person conversant to the technicalities involved in any job. To overcome

the problem of profit and growth through the soundest utilization of

human capacities effective recruitment and selection process in first step.

If it is not done well no amount of training, supervision or incentive make

for it. In view of such benefits, imparting of vocational training has been

made as an integral part of any academic structure.

According to Campbell – “Training course are typically designed

for a short term, stated set purpose, such as the operation of some pieces

of machinery which development involves in broaden education for a

long-term purpose”.

“Training is a short term process involving systematic and

organized procedure by which Non managerial personal acquire technical

Knowledge and skill for a definite purpose.”- Lawrence Steinman’s

The principle followed is to- “Put right man into right place by

careful selection and placement to make sure that he is physically and

mentally fit for the job he is expected to do”.

In B.S.N.L. training is given to engineering aspirant desiring to

secure future in the dynamic world of Telecommunications.

In this regard, I have to undergone my training at “Bharat

Sanchar Nigam Ltd.” Jaipur Telecom District

S.No. TOPICPAGES

1 TRAINING CERIFICATE i

2 PREFACE ii

3 ACKNOWLEDGEMENT iii

4 ABOUT B.S.N.L. 1

5THE TELECOMMUNICATION INFRASTRUCTURE.

TWISTED PAIR AND ISDN

5

6 THE MAIN DISTRIBUTION FRAME : MDF 17

7 EXCHANGE 20

8 ELECTRONIC BINARY VERSION EXCHANGE :E-10-B 22

9 ELECTRONIC WORLD SWITCH NETWORK : EWSD 26

10GLOBAL SYSTEM FOR MOBILE COMMUNICATION :

GSM

32

11 WIRELESS AND LOCAL LOOP : WLL 43

12 CODE DIVISION MULTIPLE ACCESS : CDMA 49

13 POWER ROOM 50

14 FUTURE PROSPECTS 54

15 CONCLUSION 58

16 BIBLIOGRAPHY59

TABLE OF CONTENT

ABOUT B.S.N.L.

On October 1, 2000 the Department of Telecom Operations,

Government of India became a corporation and was christened Bharat Sanchar

Nigam Limited (BSNL). Today, BSNL is the No. 1 Telecommunications

Company and the largest Public Sector Undertaking of India with authorized

share capital of $ 3600 million and net worth of $ 13.85 billion. It has a

network of over 45 million lines covering 5000 towns with over 35 million

telephone connections.

With latest digital switching technology like OCB,EWSD,AXE-

10,FETEX,NEC etc. and widespread transmission network including SDH

system up to 2.5 gbps, DWDM system up to 80 gbps, web

telephony ,DIAS ,VPN ,Broadband and more than 400,000 data customers ,

BSNL continues to serve this great nation .

Its responsibilities include improvement of the already impeccable

quality of telecom services, expansion of telecom network, introduction of

new telecom services in all villages and instilling confidence among its

customers.

BSNL has managed to shoulder these responsibilities remarkably and

deftly. Today with over 45 million line capacity, 99.9% of its exchanges

digital, nation wide Network management & surveillance system (NMSS) to

control telecom traffic and over 4, 00,000 route kms. of OFC network, Bharat

Sanchar Nigam Ltd is a name to reckon with in the world of connectivity.

Along with its vast customer base, B.S.N.L.’s financial and asset bases too are

vast and strong. Consider the figures, as they speak volumes on BSNL’s

standing:

The telephone infrastructure alone is worth about Rs. 1,00,000

crore(US $ 21.2 billion)

Turnover of Rs. 25,000 crore ( US $ 5.2 billion)

Add to which, BSNL's nationwide coverage and reach,

comprehensive range of telecom services and a penchant for excellence; and

you have the ingredients for restructuring India for a bright future.

Mission:

To provide world class telecom services on demand using state-of-

the-art technology for our valued customers.

Vision-2006:

That BSNL becomes the largest Telecom Company in south East

Asia with most modern state of art technology offering world –class service to

its customers.

Give paramount importance to customers care.

To expand the services of the company in all areas through

franchisees arrangement as well as alternate means.

To create a focused business orientation by suitably bringing

synergy between the Marketing and Business Development activities towards

meeting customer’s requirement.

To focus concentration for communication for masses by

expanding the services of PCOs, Internet Dhabas, Sanchar kiosks, PTIC, MCT

etc.

To expand broad band, leased lines cellular, WLL services with

state-of-the-art technology.

BSNL’S CONTRIBUTION TO DEVELOPMENT OF TELECOMMUNICATION

BSNL’s roadmap for providing customers with access to the latest in

telecommunications services without losing sight of universal service access

has been by way of utilizing optimally the existing infrastructure and

accelerating advances in technological component by innovative absorption.

The main achievements are summarized here:

Huge monolith state-of-the-art network from Kargil to

Kanyakumari and Lakshadweep to Andman Islands giving it a

national footprint.

Leader in fixed, cellular and IP networks

90% share of the market with~ 40 million fixed customers

connected to 36000 exchanges

More than 4.3 million cellular customers spread across a 1300

cities/towns

More than 4 lakh RKM of optic Fiber & 1.6 lakh RKM Digital

Microwave

An extensive copper access network ready for broadband

2.5 Gbps connectivity between all major cities through ‘Sanchar

Sagar’

Up to 2 Mbps access available to over 30,000 locations throughout

the country

Intelligent Network with Value added services

Call centers for customer care

More than 43 lakh TAX lines

7 lakh STD PCO’s

460 Satellite Stations

More than 6 lakh internet subscribers and 2 lakh CLI based users

More than 3500 internet dhabas

EXISTING COMPREHENSIVE RANGE OF WORLD CLASS SERVICES

BSNL has an impressive repertoire of traditional and modern

telecom services

Voice: a completely digital switching network for POTS

Phone plus services like call forwarding, call conferencing etc.

Data services: through ISDN and a variety of terrestrial and

satellite based packet network viz. Inet, RABMN and HVNet

Internet: available from every corner of the country on local

dialing. National Information Backbone has links of 34Mbps PDH and

STM-1 SDH capacity. About 6 lakh internet subscribers and 2 lakh CLI

based users more than 3500 Internet dhabas.

Always-on high speed Internet access

Leased Lines: BSNL provides leased lines for voice and data

communication for various applications on point to point basis.

VoIP: For more cost effective international telephony

THE TELECOMMUNICATION INFRASTRUCTURE

TWISTED PAIR AND ISDN

Until the 1940s, telephone signals for connecting customer sites to

telephone exchanges or central office used to be the aerial wires on poles.

Typically this involved a pair of wires for each phone, but in rural areas a

single wire was also used, with the path for return current being the Earth.

Underground telephone wiring began with paper-insulated copper wires - with

each pair gently twisted into a spiral pattern - in lead-sheathed cable. The

paper and lead was replaced by polyethylene insulation and sheathing in the

1950s and 60s. Some paper insulated cables are still in service, but the great

majorities of telephone connections in developed countries now uses plastic

insulation and are laid in ducts, rather than being buried directly in the soil.

The traditional telephone system couldn't handle large quantities of

data, and then came in the new services such as ISDN (Integrated Services

Digital Network) and ADSL (Asymmetric Digital Subscriber Line) also using

twisted-pair copper connections but with a difference. These cables were

designed for voice frequency performance and are also used to carry higher

frequency signals (digital information).

ISDN since 1984 allows wide-bandwidth digital

transmission using the PSTN (public switched telephone network). Under

ISDN, a phone call can transfer 64 kilobits of digital data per second. Like

ISDN, ADSL uses standard phone lines to deliver high-speed data

communications. The initial phase was for communications taking place in 64

kb/s permanent or telephone call 'pipes', but the longer-term vision of

Broadband ISDN (B-ISDN) is for much greater and more flexible data rates,

with global packet switching (or 'cell' switching, meaning short fixed length

packets) using ATM (Asynchronous Transfer Mode) rather than the slower

and less flexible 64 kb/s circuit-switched telephone exchanges.

ISDN transmission speed’s limit to 64 kbps could give a

way to ADSL technology to deliver upstream (from the user) speeds of 640

kbps and downstream (to the user) speeds of more than 6 mbps. Even better,

ADSL uses the portion of a phone line's bandwidth not utilized by voice,

allowing for simultaneous voice and data transmission.

ISDN Has emerged as a powerful tool worldwide for provisioning of

different services like voice, data and image transmission over the telephone

line through the telephone network. ISDN is being viewed as the logical

extension of the digitalization of telecommunication network and most

developed countries are in different stages of implementing ISDN.

With ISDN, voice and data are carried by bearer channels (B channels)

occupying a bandwidth of 64 Kbps (bits per second). A data channel (D-

channel) handles signaling at 16 Kbps or 64 Kbps, depending on the service

type.

TWO TYPES OF CHANNEL 1) BEARER CHANNEL (B-CHANNEL) (64kbps)

DIGITAL VOICE

64 kbps PCM

DIGITAL DATA

HIGH SPEED DATA

CIRCUIT SWITCHED

PACKET SWITCHED

FRAME RELAY

SEMIPERMANENET

OTHER

FACSIMILE

SLOW SCAN VIDEO

2) DATA CHANNEL (D CHANNEL) (16kbps)

SIGNALING

BASIC

ENHANCED

LOW-SPEED DATA

TELETEX

TERMINAL

TELEMETRY

EMERGENCY SERVICES

ENERGY MANAGEMENT

Types of Accesses:

There are two types of "accesses" (connections) for ISDN:-

1) Basic Rate Access (BRA):-

(2B+D) --> 2 Channels of 64 Kbps for Speech and Data

(Bchannel).

--> 1 Channel of 16 Kbps for Signaling(D- channel).

2) Primary Rate Access (PRA):-

(30 B+D) --> 30 Channels of 64 Kbps for speech and data

(B-channel).

--> 1 Channel of 64 Kbps for signaling (D-channel).

To access BRI (Basic Rate Interface) service, it is necessary to

subscribe to an ISDN phone line. Customer must be within 18000 feet (about

3.4 miles or 5.5 km) of the telephone company central office for BRI service.

Customers will also need special equipment to communicate with the phone

company. These devices include ISDN Terminal Adapters (sometimes called,

incorrectly, "ISDN Modems") and ISDN Routers.

The telephone companies sometimes provide its BRI customers

with a U interface. It supports full-duplex data transfer over a single pair of

wires, therefore only a single device can be connected to a U interface. This

device is called a Network Termination 1 (NT-1).

The NT-1 is a relatively simple device that converts the 2-wire U

interfaces into the 4-wire S/T interface. The S/T interface supports multiple

devices (up to 7 devices can be placed on the S/T bus) because, while it is still

a full-duplex interface, there is now pair of wires for receiving data, and

another for transmit data. Today, many devices have NT-1s built into their

design. This has the advantage of making the devices less expensive and easier

to install.

Technically, ISDN devices must go through a Network Termination 2

(NT-2) device, which converts the T interface into the S interface (Note: the S

and T interfaces are electrically equivalent).

All devices that are designed for ISDN are designated Terminal

Equipment 1(TE1). All other communication devices that are not ISDN

capable, including ordinary analog telephones, FAX machines, and modems,

are designated Terminal Equipment 2 (TE2).

An ISDN subscriber can establish two simultaneous independent calls

(except when the terminal equipment is such that it occupies two 'B' channels

for one call itself like in video conferencing etc.) on existing pair of wires of

the telephone line (Basic rate ISDN) where as only one call is possible at

present on the analog line /telephone connection. The two simultaneous calls

in ISDN can be of any type like speech, data, image etc. The call setup time

for a call between two ISDN subscribers is very short, of the order of 1 to 2

seconds. ISDN also supports a whole new set of additional facilities, called

Supplementary Services.

SIGNALING:

Instead of the phone company sending a ring voltage signal to ring the

bell in your phone ("In-Band signal"), it sends a digital packet on a separate

channel ("Out-of-Band signal"). The Out-of-Band signal does not disturb

established connections, and call setup time is very fast. For example, a V.34

modem typically takes 30-60 seconds to establish a connection; an ISDN call

usually takes less than 2 seconds.

The signaling also indicates who is calling, what type of call it is

(data/voice), and what number was dialed. Available ISDN phone equipment

is then capable of making intelligent decisions on how to direct the call.

ISDN INTERFACE

TRANSMISSION STRUCTURE

A FULL DUPLEX 155.52 MBPS

* ALL ISDN SERVICES

* IT CAN SUPPORT ONE OR MORE BASIC & PRIMARY RATE

INTERFACES

* ONE OR SEVERAL VIDEO CHANNEL DEPENDING UPON

RESOLUTION

A ASYMMETRIC SERVICE WHERE

USER TO NETWORK 155.52 MBPS

NETWORK TO USER 622.08 MBPS

* FOR VIDEO CONFERENCES

A FULL DUPLEX 622.08 MBPS

* A VIDEO- DISTRIBUTION PROVIDER

BROADBAND ISDN OVERVIEW

BISDN: BROADBAND INTERGRATED SERVICES DIGITAL

NETWORK

DATA RATE GREATER THAN PRIMARY RATE

• DESIGNED TO PROVIDE SIMILAR SERVICES AS ISDN

• BISDN IS SUBSTANTIALLY MORE CAPABLE THAN ISDN

• BISDN CAN BE USED TO DELIVER VIDEO SERVICES

• BISDN TECHNOLOGY

* ASYNCHRONOUS TRANSFER MODE (ATM)

FOR SWITCHING

* SYNCHRONOUS OPTICAL NETWORK (SONET) FOR

TRANSPORT

CONNECTIVITY:

APPLICATION

The ISDN subscriber will have full connectivity, nationally, to other

analog telephone subscribers. At present ISDN services are available to and

from India for the following countries:

Australia Austria Belgium Canada Denmark

France Germany Ireland U.S.A Italy

IsraelJapan

Malaysia NetherlandNorway

Philippines Singapore SwitzerlandU.A.E

United

Kingdom

Table 1

SERVICES OFFERED BY ISDN:

Normal Telephone & Fax (G3).

Digital Telephone -with a facility to identify the calling subscriber

number and other facilities.

G4 Fax.

Data Transmission at 64 Kbps with ISDN controller card.

Video Conferencing at 128 Kbps.

Video Conferencing at 384 Kbps (Possible with 3 ISDN lines).

ATM (Asynchronous Transfer Mode) or PVC (Permanent Virtual

Circuit).

List of ISDN stations of BSNL in India.

Variety of supplementary Services supported by ISDN.

Calling Line Identification Presentation (CLIP).

Calling Line Identification Restriction (CLIR).

Multiple Subscriber Number (MSN).

Terminal Portability (TP).

Call Hold (CH).

Call Waiting (CW).

User to User Signaling (UUSI).

ISDN ADVANTAGES

DIGITAL LINES PROVIDE HIGH DATA RATE THAN ANALOG LINE

CALL SET UP TIME REDUCED TO HALF

MULTIPLE DEVICE SHARES A SINGLE LINE

A SINGLE INTERFACE IS REQUIRED

COMMON CHANNEL SIGNALING

SIGNALS ALSO REVEALS THE CALLER ,THE SIGNAL TYPE AND DIALED NUMBER

THE MAIN DISTRIBUTION FRAME

(M.D.F.)

- Link b/w the subscriber and switch room

- It consists of two terminal point

1. N.E side

2. L.S side

It is a place where both external and internal cables are terminated. The

external individual cable caries conductors from subscribers, who are

necessarily from the same locality and as such entire no., cannot be in

numerical order .On the other hand, the internal cable conductors come from

the apparatus side in the numerical order. This cross connection between the

two cable conductors is done by means of jumper.

It carries all the protectors used in the exchange. The different

protectors that are used are:-

A) Fuse

B) Heating Coils

C) Lightening Protectors

M.D.F is the most suitable place for testing purpose. Both the

internal and the external cables are available at this frame and both external

lines and internal wiring or equipment can be tested for this purpose.

The fuse prevents heavy current from flowing into the apparatus and

them from being damaged. These fuses are generally tested i.e. rated for 1A or

3A and are of cartage of flat types.

It diffuses to some faults in the circuits an appropriate amount of

current flows through the exchange; it may not flow out the fuses if its value is

not sufficiently high, but much heat will be produced and there is a risk of

firing taking place inside the exchange from such risks, heat coils are used.

These are generally rated at 3A for 3 minutes.

Lightening protectors are used to save the equipments from

high voltage that is induced in the lines due to lightening discharge. These

consist of two carbon blocks with some insulating block or mica sheet with

holes between them. When the line voltage is high, the insulation breaks

through and earths the lines and thus saves equipment from being damaged.

They are generally rated at 500-600 volts.

The M.D.F. carries horizontal arms at the end of which fuse strips

carrying fuses are fitted and external cables are terminate on these fuse are

terminated on these fuse strips . At other end of the cross arms there are fitted

between the u spring in such a way that when either heat coil blows the line

are automatically earthed internal cables are connected from the strips carrying

protectors and the cross connection are done between the strips by means of a

jumper wire for the reasons mentioned above.

The protectors are fitted on 4springs in such a way that when attesting

plug is inserted the external lines and internal lines disconnected and separated

out at this point and so both can be tested separately from these points.

When the testing plug is inserted between pair of spring contacts. Their

contacts are broken of the spring, thus external lines are connected to the other

sides of plug and the internal lines to its inner sides.

EXCHANGE

DEFINATION:-

A system which is responsible for switching the various subscribers

TYPES OF EXCHANGE 1 ELECTROMECHANICAL

STROWGER EXCHANGE

CROSSBAR EXCHANGE

2 ELECTRONIC

EWSD EXCHANGE

E-10B EXCHANGE

WLL EXCHANGE

C-DOT EXCHANGE

E-10-BTHE ELECTRONC BINARY VERSION

EXCHANGE

The exchange consists of the following four sections:

Exploitation room

Switch room

Operation and maintenance room(O.M.C.)

Digital distribution frame(D.D.F.)

Switch Room:

It consists of three parts:

1. Connection unit::

1.1. C.S.E.(Electronic Subscriber Concentrator):

1.1.1. C.S.E.D.(distant).

1.1.2. C.S.E.L.(local).

1.2. R.L.U.(Remote Line Unit):

It consists of line cards XCJ16 and XCJ8.

It works using 4 PCM with 30 channels each.

1.3. Control Logic Shelf

1.4. U.R.M.(Multiplex Connection Unit):

These serve as junctions or circuits between the two exchanges. There

are eight modules each having four P.C.M.’s so that there a total of 32 P.C.M.

and 1024 (32X32) Junctions.

1.5. ETA:

In this section the tones are generated. 32 different types of tones can

be generated here. Frequency receivers are installed here and it works using

Inchannel Signaling. Conference circuits are also provided here.

1.6. BDA :

The primary function of this section is to make announcements on the

phone, such as “all line sin this route are busy”; “you are in a queue, please

wait.”

2. Control Unit::

The control unit is the heart of the E-10-B exchange. It performs the

various control operations through the following two sections:

2.1. Monitoring Unit:

The primary function of the monitoring unit is to provide an interface

between the Switch Room and the OMC.

2.2. MQ (Marker):

There are two markers –

MQ1.

MQ2.

The function of the two markers is to check the status of the Junction

whether it is busy or free. Both of them work on load sharing basis, i.e. the

load on both markers is same at any given time.

3. Switching Network::

3.1. CX Rack:

There is one rack with 4 Commutators; each Commutator having 16

P.C.M. the total capacity is 6000 measured in Erlangs.

3.2. Translator:

There are two translators, TR1 and TR2.

Both the translators work in standby mode. The function of the

translators is:

Routing of calls on analysis of digits.

4. Texor:

There are two texors :

TX1

TX2.

The Texors are the meters that keep track of the number of calls made.

Each subscriber has got a separate meter.

5. DSF:

The DSF works as the standby charge recording unit. The main

functions of the DSF are:

If link on OMC fails, information is saved on the

tape here.

Call details are sent to the OMC.

If the exchange fails, it can be regenerated by the

backup on OMC.

An economical choice:

When deciding between several systems , the fundamental

consideration for the purchasing authority are the operating and maintenance

costs and the quality of service offered to the user . time division switching

provides economic solutions to all these problems .

Improved performance & increased revenue:

The public are making increasingly severe demands on the telephone

services. The users’ first requirement is for a consistent in high standard of

service. This is ensured by the high level of systems reliability, the excellent

quality of digital transmission, and by the high speed of the electronic

circuitry.

The user also requires increasingly sophisticated new services the E-

10B systems offers all the services which might be expected from a modern

electronic systems equivalent to those offered by PABX systems. The other

advantage is that the operating authority achieves a better return on investment

for each subscriber line.

The introduction of new services general involves no modification of

the exchange equipment, implemented by insertion of new program segments.

THE ELECTRONIC WORLD SWITCH

NETWORK

E.W.S.D.

EWSD is one of the two technologies selected for TAX & is

also the technology for intelligent network & mobile communication.

SYSTEM FEATURES:

This system has been designed 7 manufactured by M/S Siemens

Germany name abbreviated for German equivalence.

EWSD (Electronic Switching System Digital):

Its main features are:

It can support maximum 2500 subs or 60,000 incoming or

outgoing or both way trunks.

It can carry 25,200 Erlanger traffic and can withstand 1.4

million BHCA.

It can work as local cum transit exchange.

The cards used in it have 16 ports each and 8 cards can be

given reverse facility.

In it less heat is produced in the internal circuit as a result

less number of air conditioners is required and hence the

power consumption is reduced.

Its processing speed is high.

The supervision is not proper and testing is considerably

slower.

SYSTEM ARCHITECTURE:

The main hardware units are:

1. DIGITAL LINE UNIT(DLU):

It is the functional unit on which sub lines are terminated. Analog or

digital (ISDN) subs or PBX lines are terminated on the DLU. It can be used

locally within the exchange or remote switching unit. DLU’s are connected to

EWSD subsystem via uniform interface standardized by CCITT i.e. PDC

(Primary Digital Carrier) facilitate local or remote installation.

One DLU is connected to 2 different LTG’s via 4Mbps(64 TSs)

links each toward different LTG.’s in case of remote DLU’s maximum 4

PDC’s of 2 Mbps(37TS’s) are used per DLU, two towards each LTG’s .

Hence total 124 channels are available between a DLU & 2LTG’s out of

which 120 channels are used for the user data & signaling information is

carried in TS16 of PDCO & PDC2.

In DLU the analog subs are terminated on SLMA (Subscriber

Line Module Digital) modules. Similarly digital (ISDN) subs are terminated

on SLMD (Subscriber Line Module Digital) modules. Each module can

support 8 subs hence has 8 SLCA’s (Subscriber Line Ckt. Analog) & one

SLMCD (Subs Line Module Ckt. Processor)

One DLU can carry 100 erlangs. One standard rack can support

one DLU of 944 subs each. Smaller racks (shutter) are also available for

remote DLU’s in which lesser number of subs can be equipped.

In case the link between a remote DLU & the main exchange is

broken, the subs connected to remote DLU can still dial each other but

metering would not be possible in this case, so for emergency service DLU

controller (DLUC) always contain up to date subs data.

The main components of DLU are:

SLMA or SLMD

2 DIUD(digital interface unit digital)

2 DLUC (controllers)

Mbps network for information between SLM’s&

DIUD’s

2 control network

TU , EMSD, ALEX module

2. LTG (Line/Trunk Group)

LTG’s form the interface between the digital environment of a

EWSD exchange and switching network etc.

There main features are:

Call processing functions i.e. receiving and analyzing

line and register signals, injecting audible tones,

switching user channels from & to the switching

network etc.

Safeguarding functions i.e. detecting error in the

LTG, analyzing the extent of error& initiating

counter measures such as disabling channels or lines

etc.

Operation &Maintenance functions: Acquiring

traffic data, carrying out quality of service

management etc.

Functional units of the LTG are:

LTU (LINE or Trunk Unit) is a logical unit that comprises of following

units:

Digital Interface Unit (DIU) for connection of 2Mbps

digital trunks.

Codes Receiver (CR) for multifrequency code

receiver for trunks.

B for conference calls.

Automatically test equipment for trunk.

Signaling Unit (SU) comprises, Tone

Generator (TOG) for audible tones.

Code Receiver for MFC signaling.

Pushdown button dialing & receiver module for

continuity check.

3. SN (Switching Network)

Different peripherals units of EWSD i.e. LTG’s, CCNC, MB are

connected to the SN via highways called SDC’s (secondary digital carriers)

which have 128 channels each.

The SN consists of several duplicated, Time stage groups (TSG)

&Space State Groups (SSG) housed in separate racks. Connection paths

through the TSG’s &SSG’s Housed in separate racks. Connection path TSG’s

& SSG’s are switched through the Switched Group Controls(SGC) provided in

each TSG & SSG , in accordance with the switching information from the

coordination processor (CP). The SGC’s also independently generate the

setting data & set the message channels for exchange of data between the

distributed controls. The SN is always duplicated. Each connection is switched

simultaneously through the planes, so that a standby connection is always

immediately available in the event of a failure.

G.S.M.

THE

GLOBAL SYSTEM OF MOBILE COMMUNICATION

The GSM Signaling Platform provides SS7 signal processing

and subscriber identification translation that enables larger GSM carriers to

offer wholesale roaming services to smaller or emerging GSM carriers who

may otherwise not be able to offer extensive roaming coverage. Large carriers

can also take advantage of this platform to provide similar roaming

capabilities to affiliate companies in different global markets.

Subscribers in a GSM network have an International Mobile

Subscriber Identity (IMSI) that identifies them in their carrier's network. For

subscribers to roam outside of their home network, their carrier must negotiate

roaming agreements with other network operators so the visited network

recognizes the subscriber's IMSI and allows roaming to proceed. Negotiating

and administering these agreements can be time consuming, and there may be

a limit on how many roaming agreements a visiting carrier may choose to

support. As a result, emerging or smaller carriers can have difficulty offering

extensive GSM roaming coverage.

The larger carrier or broker provides the smaller carrier with a

second range of subscriber IMSIs. The larger carrier’s IMSI (the second) is

stored in the subscribers mobile phone along with the original IMSI that is

provided by the smaller carrier. When the subscriber roams into another

network, the larger carrier’s IMSI is activated because the smeller’s IMSI is

not recognized. This second IMSI now identifies the roaming customer as the

larger carrier’s subscriber. This results in the IMSI query being sent to the

GSM Signaling platform (located in the larger carrier’s network) where it is

translated (mapped) to the smaller carrier’s IMSI, then sent to be validated by

the small carrier’s HLR. The translation application is referred to as Dual

International Mobile Subscriber Identity (DIMSI) Mapping.

The GSM Signaling Platform enables a larger GSM carrier

to offer roaming capabilities to smaller carriers or divisions within their own

company by acting as a broker. The broker carrier or parent company utilizes

the GSM Signaling Platform in conjunction with their existing roaming

agreements and network infrastructure and then establishes a billing

mechanism (transaction or usage-based) to charge the smaller carrier-

customer, if necessary.

The GSM Signaling Platform provides the critical interface to

carrier SS7 networks to ensure secure validation message processing

Cellular is one of the fastest growing and most demanding

telecommunications applications. And the continuous advancement in this

technology has provided many options to a consumer. .

During the 80s, when the cellular system was introduced, each

nation had its own system. As a result, a couple of problems arose. Firstly, the

equipment was limited to operate only within the boundaries of a country and

secondly, the market for mobile equipment was also limited. In order to

overcome these problems, the conference of European Posts and

Telecommunications (CEPT) formed the Group Special Mobile (GSM) to

create a common European mobile telephone standard.

The GSM later came to be known as Global Service for

Mobile communications (GSM).At the end of 1997, GSM was made available

in more than 100 countries. Today it has become the global standard in Europe

and Asia.

G.S.M. operates in 900-MHz – 1800MHz. If one has to connect to the

specific service provider in different countries, GSM-users simply need to

switch Subscriber Identification Module (SIM) cards. As per GSM

technology, a mobile unit logs on to the network after being switched on. The

mobile unit tries to contact a nearby BTS, which then transmits all the

frequencies of the neighboring BTS’ to the mobile unit, which identifies the

frequency on which the reception is the best and passes on the information to

the BTS.

The BTS then transmits the information to the BSC which has the

deciding power as to which BTS should the mobile unit be assigned.

GSM Network Elements

It consists of:

Handset

BTS: Base Transceiver Station

BSC: Base Station Controller

MSC: Mobile Switching Center

HLR/VLR: Home Location Register/Visiting Location Register

SIM Card: Subscriber Identity Module Card

Mobile Handset (MH)

Used by the subscriber to access the GSM network via the air interface

It contain a radio transceiver, a digital signal processors

It need a Subscriber Identity Module (SIM) which contains the

subscriber-specific data to access GSM network, except in case of

emergency call

Base Transceiver Station (BTS) Responsible for communication to and from MHs via air interface

BTS is used one for each cell having radius 100m to 35km

It includes radio antenna ,a radio transceiver

BTS separates the speech and control signaling associated with a MH

and sends them to the BSC on separate channels

Base Station Controller (BSC)

Monitor and Control several base stations

Reserve radio frequencies, manages the handoff of a mobile unit from

one cell to another within BSS, also control paging

Channel allocation and release

BSC is the interface between MSC and BTS. BSC is connected on one

side to several BTSs and on the other side to the MSC

Mobile services SwitchingCenter (MSC)

MSC is the interface between GSM network & PSTN (Public Switched

Telephone Network)

manages the handoff of a mobile unit from one cell to another in

different BSS

Authenticates users and validates their account

Home Location Register (HLR) Contains information of network subscribers which exactly belongs to

this MSC.

The data stored in HLR is of a semi permanent nature and does not

usually change

Visitor Location Register (VLR) Contains the relevant data of all MHs currently located in a serving

MSC

The permanent data is the same as data in the HLR

The temporary data includes

Temporary Mobile Subscriber Identity (TMSI)

SIM Cards SIM cards are embedded with a microprocessor

Stores customer identity information and is made to fit inside

the cellular phone

Memory capacity

1K, 4K, 8K, 16K

Subscriber Identity Module (SIM)

Subscriber Identity Module Contains

phone number international mobile subscriber identity (IMSI) status of SIM authentication key PIN (personal identification code)

Operation subsystem

The OSS (Operation Subsystem) enables centralized operation,

management, and maintenance of all GSM subsystems

Components

Authentication Center (AUC)

generates user specific authentication parameters on

request of a VLR

authentication parameters used for authentication of

mobile terminals

Equipment Identity Register (EIR)

Keep track of the type of equipment that exist at the

mobile station

stolen or malfunctioning mobile stations can be locked

Operation and Maintenance Center (OMC)

different control capabilities for the radio subsystem

and the network subsystem

Time and Frequency Multiplex

Advantages:

Better protection against tapping

Protection against frequency interference

Higher data rates compared to code multiplex

GSM System Architecture

PSTNPSTN

Data Terminal

HLR/VLR

MSCBSC

OMC(Operation & Maintenance

Center)

OperationTerminal

BTS

Handset

Network sub-system PSTNRadiosub-system

Mobilestation

SIMcard

Performance characteristics of GSM

Communication

mobile, wireless communication; support for voice and data

services

High capacity

Smaller cells, more customers per cell

High transmission quality

high audio quality and reliability, uninterrupted phone calls at higher

speeds (e.g., from cars, trains)

Disadvantages of GSM

No full ISDN bandwidth of 64 kbit/s to the user

Reduced concentration while driving

misuse of private data possible

High complexity of the system

Differences between GSM & CDMA

While TDMA and FDMA are the types of multiplexing in GSM, CDMA works on spread spectrum. However the bandwidth available is same for both the technologies, which is 800, 1800 and 1900 MHz.

While GSM cannot add more than a fixed number of subscribers in a cell, the capacity of the system is not rigid in CDMA. The biggest advantage with GSM is its widespread network in Europe and Asia, whereas CDMA is predominant in US and South Korea. The user of GSM is enabled an easy international roaming. As far as SMS, gaming and internet is concerned, both GSM and CDMA score an equal point.

GSM has already set a standard in India. Being a patented technology, all CDMA equipments and handsets require a royalty to be paid

W.L.L.

(WIRELESS AND LOCAL LOOP)

Why Digital Wireless Communication?

Increased Spectrum Utilization.

Robust Radio Access.

Matured Digital Signal Processing.

High Integration on VLSI.

High reliability and precision.

Compatibility with Data Communication and Digital

Networking.

Reduced Cell Equipment Size and Cost.

Introduction to WLLDefinition:

A local telephone system without wire line connected.

Fixed radio communication system.

What is WLL?

WLL is sometimes called fixed cellular.

WLL system can be treated as wire line loop without wire line

connected.

WLL is normally used for Rural or unpopulated.

WLL can be quick solutions for developing telephones

infrastructure.

WLL: NETWORK CONFIGURATION DIAGRAM

Why to use WLL?Eliminates many problems and reduces cost inherent to wire line

loop system in certain areas.

Decreases the time to deploy a network.

Mobility and Flexibility

Advantages of WLL:Advantage over wire line:

Ease of installation and deployment and lower cost.

Ease of operation, administration and maintenance.

Advantage over mobile:

Bigger coverage area.

Improved signal and reduced interference.

Higher capacity.

Fixed to Fixed propagation.

Frequency reuse reduced.

WLL Attributes:Range can be 62 Km (best propagation condition)

Based on free space loss.

Based on high gain antenna.

Based on spread spectrum waveform.

The capacity is higher than that of mobile radio.

Services:Voice.

Data services.

Customer services.

Mobility.

Subsystems of WLL

Base Station Controller (B.S.C.)

It is situated between the P.S.T.N.-L.E. & B.T.S. It has BTS

status management function .Its major functions are:

Call processing

transport service management

voice coding

optimal voice selection

provision of supplementary services

message distribution function

call resource management

P.S.T.N. interface

operation and maintenance function

Specifications of B.S.C.

No. of subscribers:-9950

No. of channels: - 1024

Ports to B.T.S. 48 E1 to P.S.T.N. 32E1

Power supply -48V D.C.

Normal working temperature:-25 C

Interface between B.S.C. and P.S.T.N. is given by

the V5.2 Protocol. It consists of three layers:-

Physical Layer

Data Link Layer

Network Layer

Base Transceiver Station (B.T.S.)

It interfaces with the subscriber side in the wireless mode

and the B.S.C. via E1. It carries out the channel management & power control

function between the wireless interface sections.

Functions provided by the B.T.S. are:-

Call processing function

Wireless resource management function

Software downloading

Operation & maintenance function

Fault management

Testing function

Overload control function

Statistics & management function

Specifications of B.T.S. are:-

Operation Band 1800 MHz-1900 MHz

Voltage supply input 48V but the voltage is step down to 24V

by a D.C. - D.C. converter.

It has +-10 % overloading capacity

Connections in B.T.S. are 4000 +-10% (urban)

1000 +-10% (rural)

Base Station Manager (B.S.M.) It is the heart of the W.L.L. system. Database is managed here .

Functions performed by the B.S.M. are:-

Configuration management

Performance management

Fault management

Security management

Software downloading

Operator interface function

Specifications of B.S.M. are:-

Product Name: - SUN ULTRA – 5

CPU – 270MHz Freq ULTRA SPARC – 3

Main memory: - 256 MB

GUI: - X-Win Motif 2.x

Operating System: - Solaris V2.x

Hard Disk: - 4.2 GB

The system works on the technology known as:

CODE DIVISION MULTIPLE ACCESS (C.D.M.A.) Developed by Qualcomm for the US Military, Code Division

Multiple Access is a system that enables many users to share the same

frequency band at the same time.

CDMA is a spread spectrum technology whereby multiple

users share the same time and frequency allocation in a given band. Each

speech signal is modulated (spread) across an entire band. The respective

receiver demodulates and interprets the signal using relevant code that is

embedded in the signal. The final signal contains only the relevant

conversation.

The CDMA based mobile technology was introduced in India

to provide WLL services as the GSM was the choice for full mobility. CDMA

based WLL operators were given license of operation as fixed line operators.

As CDMA can very well connect large geographical area, WLL operators

were given the rights to provide "limited mobility" whereby a WLL operator

could allow network coverage to the boundary of a Short Distance Charging

Area (SDCA).

POWER ROOM

INTRODUCTION

Power room is designed to deliver continuous and filtered power

supply for electronic switching type telephone exchange (E-10-B).

Terminal Equipments

The power plant consists of the following sections:

The rectifier section.

Float cum battery section.

Switching cubicle section.

Batteries

1. Rectifiers:

Rectifiers operate with 3-phase a.c. input to deliver highly stabilized d.c.

output voltage within close limits under varying input voltage and output load

conditions .

Rectifiers can be classified as:

Conventional Rectifiers.

Switch Mode Rectifier(S.M.R.)

Conventional Rectifier & Switch Mode Rectifier

Conventional rectifiers are also known as float rectifier because the

batteries connected in parallel to it floats and the output of the battery is less

than the rectifiers. They require frequent maintenance and are less efficient

than SMR which is maintenance free. If the capacity of the exchange has to be

increased then several Switch Mode Rectifier’s (SMR) can be connected in

series to meet the requirement. This is an additional feature of SMR over the

conventional type rectifiers.

The major sections of the unit are

Input section .

Control section.

Converter section.

Alarm section.

Output section.

2. Float Cum Battery Charge Section

This section is given this name because it works as the rectifier

cum battery charger. When the battery gets discharged working under

the conditions of mains failure; this section continues to recharge the

battery.

3. Switching cubicle section

Float rectifiers can work in parallel or in load sharing mode with

other float rectifiers of any rating when connected to F.C.B. cum

switching cubicle. There is a rack in the float rectifiers through which

the required power is sent to the particular exchange using knife

switches and fuses via set of cables. this is a useful section since power

in individual section of section of exchange can be cut off using knife

switches.

4. Batteries

Batteries can be classified as conventional and maintenance free.

Maintenance free batteries consist of 24 cells termed as

VRLA.As the name indicates , they require less maintenance and

hence are more efficient.

life of Maintenance free batteries is less than conventional

ones and any fault cannot be corrected in these batteries. Batteries are

connected in parallel with the rectifiers. Under the condition of power

failure when the rectifier stops working, the load automatically

switches over to battery side.

Battery charging:

When the specific gravity (S.G) in a majority of cells has

fallen below 1.195 the battery should be charged at the normal

recharged current. Unit cell rating at 2.3 V per cell. The charging

current continues till the specification gravity and the voltage remains

constant for the three consecutive half housely reading conditioning

charges with decorative discharge.

BLOCK DIAGRAM OF POWER ROOM

EXCHANGED.C. DIODE SCR / THYRISTER

TRANSFORMERA.C.

440 VOLT 80-100 VOLT

FUTURE PROSPECTS

BSNL's future plan include a fast expansion program of increasing the

present 34 million lines to twice that number by 2005 and some 120 million

lines by 2010.

The shift in demand from voice to data domination, and from wire line

to wireless, has revolutionized the very nature of the network. BSNL has

already set in place several measures that should enable it to evolve into a

fully integrated multi-operator by 2005 and its incumbent status, size,

infrastructure and human resource should certainly, give it a distinct

advantage.

Consolidation of the network and maintaining high quality of service

comparable to International standards is the key aim of the Growth Plan.

Objective of the plan are:

The telephone connection shall be provided on demand and it

shall be sustained.

The Network shall be made fully digital. All the technologically

obsolete analog exchanges will be replaced with digital

exchanges.

To provide digital transmission links up to all SDCA ’s.

Digital connectivity shall be made available to all the exchanges

by 2007.

Extensive use of Optical fiber System in the local, Junction and

long distance network so as to make available sufficient

bandwidth for the spread of Internet and Information technology.

ISDN services shall be extended to all the district headquarters,

subject to demand.

To provide Intelligent Network Services, progressively all over

the country (major cities have already been covered).

To set up Internet Nodes progressively up to District headquarters

level.

Upgrading existing STD/ISD PCOs to full fledged Public Tele-

Info Centers (PTIC) for supporting Multi media capability and

Internet Access.

Replacement of life expired, analogue coaxial and radio systems.

Introduction of Wireless technology (Supporting Internet Access)

and optical fiber technology in subscriber loop.

Introduction of latest telecom services like National directory

enquiry, computerization etc.

Cellular Mobile Service 'Cell One' of BSNL was launched on

19th October 2002 . The scheme will cover 4 million customers

in two phases. Phase-I will cover about 1.5 million customers

covering about 1000 cities during 2002-03, which will be

expanded to 4 million in phase-II.

Projects Recently Implemented Or Under Development

National Internet Backbone of BSNL

Voice over IP

Broadband Services - ADSL & High Speed Internet

Managed Leased Line Network (MLLN)

Access Network - LMDS, DLC‘s, RLC etc.

Internet Exchange Points - IXP & Internet Data Centers (IDC)

E-Commerce

CONCLUSION

The works on the summer training was a wonderful experience in my life. The

training has been extremely useful in developing my professional skills and

personality. The training help me a lot to adapt myself to actual working

environment and to work in coordination with the other team members.

Further, the guidance, support, cooperation and assistance provided by my

seniors and colleagues at NTPC, Faridabad helped me to better understand

the real working environment. The practical experience gained during the

short period of four weeks will go a long way in achieving my real goal and

ambition in my life.

BIBLIOGRAPHY

The material used to prepare this report has been taken from the

following sources.

Ahujha`s manual

Department manual (prepared by BSNL training centers)

Web sites

www.bsnl.co.in

www.ctr.ac.uk.in

www.gsmworld.com

www.iec.org .

Other materials provided by the department