Project Report

SIX MONTHS INDUSTRIAL TRAINING REPORT_________________________________________________________________________________________________

Six Months Industrial Training Report

In partial fulfillment of the degree of Bachelor of Technology in Electronics & Comm. Engg.

STUDY OF GSM BASICS,ROAMING TESTING AND GENERATION OF DAILY REPORTS

Undertaken AtBHARTI Mobile Ltd.

C-25, phase IIMOHALI

Submitted By: Nandita

225043454 E.C.E

S.U.S.C.E.T,TANGORI(MOHALI)

Punjab Technical University,Jalandhar

NANDITAECE 225043454

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“Say a word of gratitude and splendour- In a moment it is gone, But there are a hundred ripples Circling on & on & on……………………….”

I, Nandita, student of S.U.S.C.E.T, TANGORI, 6th Semester (E.C.E) express my heartfelt thanks to Mr. Gurcharan Singh (Training and Placement Officer) for providing me his valuable guidance and sharp vision to undertake this six months industrial training.

Training in an organization like “AIRTEL” which is fuelled by the individuals with so much zest & energy, “teaming” up to form a formidable force, was in itself a true learning experience which is going to help me immensely in my career. There is no substitute to “Teamwork”. This is one of the many lessons I learnt during my training in “BHARTI MOBILE Ltd”.

I hereby convey my thanks to all those whom have rendered their valuable help, support and guidance during my training period. First of all, I would like to thank Mr.Shankar Halder(Chief Technical Officer) for granting me the permission to work as a Trainee in this esteemed company & for providing me all the facilities.

I would like to express my deepest gratitude to Mr. H.K. Mishra (D.G.M, NSS), Mr. Munish Nagpal (Senior Manager ,NSS) & Mr.Ashwani Shukla (Manager , NSS) for their support ,co-operation and valuable guidance throughout the training period.

I would like to pay my heartiest thanks to Mr.Vivek Kaushik(Engineer,NSS), Ms. Neeti Saxena(Engineer,NSS ) , Ms. Harmeet Virk(Engineer,NSS )and Mr. Rahul Bhatia(Engineer,NSS) for her vital help in clarifying various concepts and helping at every stage during the training period.

NANDITA


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With the ongoing telecom revolution where innovations are taking place at the blink of an eye , it is impossible to keep the pace with the emerging trends. In organization where Making Things Right in the first instance is the driving motto ,perfection and accuracy are inevitable.

Excellence is an attitude that the whole of the human race is born with. It is the environment that makes sure that whether the result of this attitude is visible or otherwise. A well planned ,properly executed and evaluated industrial training helps a lot in inculcating a professional attitude. It provides a linkage between the student and industry to develop an awareness of industrial approach to problem solving ,based on a broad understanding of process and mode of operation of organization.

During this period , the students get the real ,first hand experience for working in the actual environment. Most of the theoretical knowledge that has been gained during the course of their studies is put to test here. Apart from this ,the students get an opportunity to learn the latest technology ,which immensely helps them in building their career.

I had the opportunity to have a real experience on many ventures ,which increased my sphere of knowledge to a great extent. This training had finally made me step into the ongoing telecom revolution and gradually become the part of it.All the credit goes to organization Bharti – which in true self made the telecom revolution happen.

In this report the GSM technology and the various parameters governing the performance of the mobile network has been discussed.


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Topic Page No. Company Profile 6

Business Strategy 8

Company achievements 9

Branches of Bharti 12

Technical Department Hierarchy 13

GSM Basics 14

GSM Architecture 18

Channels 22

Frequency band of operations 22

Access Method 24

Air Interface Channels 25

Call Set-Up 29


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Transmission Problems 34

Solution to transimission problems 37

Wireless Concept 39

GSM Transmission process 41

GSM Network identities 49

GSM Subscriber services 55

MY DEPARTMENT(NSS) 58

NSS Components 60

Work Profile 68 Roaming testing

68 Short test

68 Long test 71 Prepaid test 75 GT and IMSI Analysis 76 Health checkup 84 MMS,MASALA and GPRS Dump 87 HGSDP Dump 89


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The SCR Sheet 91 The Daily GSM MAPA 93 C7& Processor Load

101

INDUSTRY APPLICATION 103

CONCLUSION 104

BIBLIOGRAPHY 105

Spearheading the Indian telecom revolution for two decades


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Bharti Enterprises, India’s leading telecom conglomerate has been at the forefront of technology and has revolutionized with its world class services.Established in 1976, Bharti Enterprises has been a pioneering force in the telecom sector with many firsts and innovations to its credit. Working on the principle of providing end to end communication solution across the telecom value chain from manufacture of hardware to development of telecom software and from fixed line to cellular and wireless services, e-commerce, broadband, domestic long distance, undersea cable, infrastructure development and business solutions. Bharti Enterprises under cable chairmanship of Sunil Bharti Mittal is the only company to have brought to India the excellence and expertise of leading Telecom players of the world., Bharti Telecom, the manufacture division of Bharti is the largest sets under the brand name Beetel. Bharti televentures, the services division of bharti has major interests in Basic, long Distance and Cellular, Broadband and Infrastructure Operations in the country.

NORTHERN REGION

After touching the hearts of more than 1 million customers and winning the Techies Award for Best Cellular Services for four consecutive years, Bharti Cellular has reached Punjab- the land of colors, festivals, industrious people and emerging opportunities, Haryana- the place of handicrafts & textile industry, and Himachal Pradesh the ultimate destination for nature lovers.Punjab is said to be a sweet home-coming for Bharti, launched on Feb 8,2002. With over 25000 bookings on day 1 and having 50,000 customer in just 75 days it is already on an expressway to success. Ahead of competitors in Himachal, and with grand start in Haryana, Bharti is here to take care of communication needs and live up to the true spirit of Northern Region of Excellence.

Highlights of history, collaborations and achievements are given below.

“As we spread wings to expand our capabilities and explore new horizons, the fundamental focus remains unchanged: seek out the best technology in the world and put it at the service of our ultimate user: our customer.”

Sunil Bharti Mittal


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Bharti Enterprises has been at the forefront of technology and has revolutionized telecommunications with its world-class products and services. Established in 1985, Bharti has been a pioneering force in the telecom sector with many firsts and innovations to its credit, ranging from being the first mobile service in Delhi, first private basic telephone service provider in the country, first Indian company to provide comprehensive telecom services outside India in Seychelles and first private sector service provider to launch National Long Distance Services in India. As of September 30, 2003, Bharti had approximately 5.11 million total customers – nearly 4.62 million mobile and 496,700 fixed line customers.National Long Distance Services in India. As of September 30, 2003, Bharti had approximately 5.11 million total customers – nearly 4.62 million mobile and 496,700 fixed line customers.Its services sector businesses include mobile operations in Andhra Pradesh, Chennai, Delhi, Gujarat, Haryana, Himachal Pradesh, Karnataka, Kerala, Kolkata, Madhya Pradesh circle, Maharashtra circle, Mumbai, Punjab, Tamil Nadu and Uttar Pradesh (West) circle. In addition, it also has a fixed-line operation in the states of Madhya Pradesh and Chattisgarh, Haryana, Delhi, Karnataka and Tamil Nadu and nationwide broadband and long distance networks.Bharti has recently launched national long distance services by offering data transmission services and voice transmission services for calls originating and terminating on most of India's mobile networks.The Company is also implementing a submarine cable project connecting Chennai-Singapore for providing international bandwidth. Bharti Enterprises also manufactures and exports telephone terminals and cordless phones. Apart from being the largest manufacturer of telephone instruments, it is also the first telecom company to export its products to the USA.

Business Strategy

Bharti Tele-Ventures' strategic objective is“to capitalize on the growth opportunities that the Company believes are available in the Indian telecommunications market and consolidate its position to be the leading integrated telecommunications services provider in key markets in India, with a focus on providing mobile services”.

The Company has developed the following strategies to achieve its strategic objective:

Focus on maximizing revenues and margins;

Capture maximum telecommunications revenue potential with minimum geographical coverage;

Offer multiple telecommunications services to provide customers with a "one-stop shop" solution;


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Position itself to tap data transmission opportunities and offer advanced mobile data services;

Focus on satisfying and retaining customers by ensuring high level of customer satisfaction;

Leverage strengths of its strategic and financial partners; and

Emphasize on human resource development to achieve operational efficiencies.

Businesses

Bharti Tele-Ventures current businesses include -

Mobile services

Fixed-line

National and international long distance services

VSAT, Internet services and network solutions

Competitive Strengths

Bharti Tele-Ventures believes that the following elements will contribute to the Company's success as an integrated telecommunication services provider in India and will provide the Company with a solid foundation to execute its business strategy:

Nationwide Footprint - As of September 30, 2003, approximately 91% of India's total mobile subscribers resided in the Company's fifteen mobile circles. These 15 circles collectively accounted for approximately 56% of India's land mass;

Focus on telecommunications to enable the Company to better anticipate industry trends and capitalise on new telecommunications-related business opportunities;

The strong brand name recognition and a reputation for offering high quality service to its customers;

Quality management team with vision and proven execution skills; and

The Company's strong relationships with international strategic and financial investors such as SingTel, Warburg Pincus, International Finance Corporation, Asian Infrastructure Fund Group and New York Life Insurance.


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COMPANY ACHIEVEMENTS1996

BTNL’s winning bid for Madhya Pradesh Service Area for Fixed Line telephone services.

Formed Casio Bharti Mobile Communications Limited a joint venture with Casio & Mitsui of Japan to manufacture & market Radio Pagers.

Formed Bharti Duraline Pvt. Ltd., a Joint Venture with Duraline Corporation, USA to manufacture HDPE Ducts.

Formed a Joint Venture Company Bharti Tele-Ventures Ltd. with Telecom Italia, Italy to promote various telecom projects in India.

BTNL commercially launched cellular services in Himachal Pradesh.

1997 British Telecom joined the Consortium of Bharti Cellular. BTNL granted License for Madhya Pradesh Fixed Line services. Bharti & BT formed a joint venture Bharti BT Limited for a VSAT

project. Bharti Global granted the license to operate comprehensive telecom

services in Seychelles as Second Operator.

1998

First ever Indian Private Fixed Line Service launched in Indore, Madhya Pradesh on 4th June, 1998 by BTNL.

Bharti BT Internet Limited formed to offer Internet & E-Commerce Services in collaboration with British Telecom.

Services launched in Seychelles on 12th December, 1998. British Telecom consolidated its shareholding in Bharti Cellular.

1999

Bharti BT Internet launches Mantra Online Internet services in May. EM Warburg Pincus, one of the largest International Private Equity

Investors, joins BTVL. Acquired controlling stake in J T Mobiles - Cellular Operator in Andhra

& Karnataka (Now Bharti Mobile Limited). Intel takes Equity stake in Bharti Tele-Spatial and Bharti Telesoft.

2000

New York Life International takes stake in Bharti Cellular. Launch of AIRTEL and MAGIC brands in Karnataka and Andhra

Pradesh. Bharti Telesoft opened its overseas offices in UK & USA. Acquire controlling stake in Skycell, Chennai


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Singapore Telecom decides to invest in Bharti and becomes partner in BTL & BTVL.

Entered into a JV with Singapore Telecom Intnl, for Submarine Cable project between Singapore-Chennai and Mumbai-Singapore.

2001

Entered into a joint venture with Singapore Telecom International for Submarine Cable project between India and Singapore

Acquired cellular operation from Spice Cell in Kolkata. Acquired eight cellular licences as fourth operator for the circles of

Mumbai, Maharashtra, Gujarat, Haryana, UP (West), Kerala, Tamil Nadu and Madhya Pradesh.

Crossed the 1 million subscriber base mark in October 2001. Acquired four licences to offer basic services in Delhi, Haryana, Tamil

Nadu and Karnataka circles. Punjab license restored to Bharti Mobile by the DoT and migration to

NTP- 1999 accepted Bharti Telesonic has entered into a license agreement with DoT to provide

National Long Distance Services in India and has been the first service provider to start service in the country.

Bharti Aquanet, Bharti Telesonic and Bharti Cellular have entered into license agreements with the DoT to provide ISP services in India

Bharti launches India’s first private sector national long distance service under the brand name IndiaOne.

2002

Bharti launched cellular services in Punjab Bharti listed on the National stock Exchange, Bombay Stock Exchange

and the Delhi Stock Exchange on February 18, 2002. Bharti received a letter of intent from the Government of India to provide

international voice services.

2003

Bharti launched New NDC 9872 for Punjab Bharti completed 9,00,000 Customers in Punjab. Bharti passed milestone of 100 Direct International tie-ups which includes

59 different countries.

2004 Bharti launched GPRS with 14 International Operator. Widest coverage which includes 137 countries and 337 Global Networks. Deepest Coverage which includes 16 Indian States and 1400 towns. Bharti was the first corporate to launch EDGE in Punjab.Bharti started

working on launching their cellular services in Jammu & Kashmir and Rajasthan


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Airtel wins the “World Communications Best Brand Award”

2005 Bharti Tele-Ventures is the "Indian Mobile Operator of the Year 2005” Ericsson and Bharti sign managed capacity expansion contract for rural

India The first Indian company to supply phones under their own brand –

Beetel - in the retail segment to the UAE Sunil Bharti Mittal, Chairman & Managing Director , Bharti Enterprises

gets 'The Best Asian Telecom CEO' award. Bharti Tele-Ventures is Asia's 'Best GSM Carrier'.

Airtel Completes Its 23 Circle All India Footprint Airtel Launches India's First Stock & Portfolio Tracker On The Mobile Bharti Launches Airtel In North East & Assam Airtel Becomes The First GSM Operator In The Country To Cross The

10 Million-Customer Milestone

BRANCHES OF BHARTI


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TECHNICAL DEPARTMENT HIERARCHY

The office of AIRTEL is located at Mohali. The Technical department hierarchy is shown below.


I.T. I.T.

PROJECTMANAGEMENT

PROJECTMANAGEMENT

HUMAN RESOURCE

HUMAN RESOURCE

TECHNICALTECHNICAL

FINANCEFINANCE

MARKETINGMARKETING

CUSTOMER CARE

CUSTOMER CARE

BHARTIENTERPRIS

E

BHARTIENTERPRIS

E

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MY DEPARTMENT

NETWORK AND SWITCHING SUBSYSTEM (NSS)

I did my six months training in NSS , where I learnt about various tests which are performed for launching roaming with different network operators and various reports which are made on daily basis for the analysis and maintenance of entire network of Punjab ,Haryana ,HP and J&K. Along with the basic functions of NSS, I also had an insight into few other concepts of GSM which helped me get through with my work.


TECHNICAL DEPARTMENTTECHNICAL DEPARTMENT

OPERATION AND MAINTENENCE (O&M)OPERATION AND MAINTENENCE (O&M)

NETWORK PLANNINGNETWORK PLANNING

OPERATION MAINTAINENCE &CONTROLLING (OMC)

OPERATION MAINTAINENCE &CONTROLLING (OMC)

NSSNSS

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Introduction To GSM (Global System for Mobile Communications)

Why “cellular”?

Radio spectrum is very limited, that’s why we have only 10-25MHz dedicated to wireless communication. Such narrow bandwidth allows 100-400 channels of reasonable quality, which is not rational and commercially not profitable to develop network for such small number of mobile subscribers. Genius idea lead to division of the whole geographical area to relatively small cells, and each cell may reuse the same frequencies by reducing power of transmission. Each cell has its own antenna (base station), and all base stations are interconnected using microwave or cable communication.

GSM (Global System for Mobile Communication)

DefinitionGlobal system for mobile communication (GSM) is a globally accepted standard for digital cellular communication. GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard that would formulate specifications for a pan-European mobile cellular radio system operating at 900 MHz. It is estimated that many countries outside of Europe will join the GSM partnership.

THE GEOGRAPHICAL NETWORK STRUCTURE


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Every telephone network needs a specific structure to route incoming calls to the correct exchange and then on to the subscriber. In a mobile network, this structure is very important because the subscribers are mobile.

CELLA cell is the basic unit of a cellular system and is defined as the area where radio coverage is given by one base station. Different cells are identified by a unique number called Cell Global Identity (CGI). In a complete network the number of cells is large.

There is a limited number of frequencies available within the frequency band specified for cellular systems. Each operator licensed to run a cellular network, has been provided with a number of frequencies. A cell has one or several frequencies, depending on traffic load. To cover a country, for example, the available frequencies must be reused. The same frequency cannot be used in neighbouring cells due to interference.

Neighbouring cells can’t have the same frequency.

LOCATION AREA


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The Location Area (LA) is defined as a group of cells. The system uses LA to search for subscribers in active state. When there is a call for a mobile station, a paging message is broadcast to all cells belonging to a specific LA. A LA is the part of the network in which a mobile station may move around freely without reporting its location to the network. Different location areas can be identified by the system using the Location Area Identity (LAI).

Location Areas

MSC/VLR SERVICE AREAThe mobile station is registered in a database called Visitor Location Register (VLR). MSC and VLR are always implemented in the same node in all Ericsson GSM networks, thus the area is often called MSC/VLR Service Area. A MSC/VLR Service Area is made up of a number of LAs. It represents the geographical part of the network that is covered by one MSC. To route a call to an MS,the subscriber’s MSC service area is also recorded and monitored..

Network Areas

PLMN SERVICE AREA


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The Public Land Mobile Network (PLMN) is a geographical area served by one network operator and is defined as the area in which an operator offers radio coverage and possibility to access its network.

PLMN Service Area

GSM SERVICE AREAThe GSM service area is the entire geographic areas in which a subscriber can gain access to the GSM network.The GSM service area increases as more operators sign contract agreeing to work together. As shown in Figure, these areas include cells, location areas (LAs), MSC/VLR service areas, and public land mobile network (PLMN) areas.

GSM Network ArchitectureGSM Network Architecture


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The GSM network can be divided into four main parts:

Mobile Station (MS).

Base Station Subsystem (BSS).

The Network and Switching Subsystem (NSS).

Operation and Support Subsystem (OSS).

Mobile StationMobile Station

A Mobile Station consists of two main elements:

The mobile equipment or terminal.

The Subscriber Identity Module (SIM).

The TerminalThe Terminal

There are different types of terminals distinguished principally by their power and application:


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The `fixed' terminals are the ones installed in cars. Their maximum allowed output power is 20 W.

The GSM portable terminals can also be installed in vehicles. Their maximum allowed output power is 8W.

The handheld terminals have experienced the biggest success thanks to their weight and volume, which are continuously decreasing. These terminals can emit up to 2 W. The evolution of technologies allows decreasing the maximum allowed power to 0.8W.

The SIMThe SIM

The SIM is a smart card that identifies the terminal. By inserting the SIM card into the terminal, the user can have access to all the subscribed services. Without the SIM card, the terminal is not operational. The SIM card is protected by a four-digit Personal Identification Number (PIN). In order to identify the subscriber to the system, the SIM card contains some parameters of the user such as its International Mobile Subscriber Identity (IMSI). Another advantage of the SIM card is the mobility of the users. In fact, the only element that personalizes a terminal is the SIM card. Therefore, the user can have access to its subscribed services in any terminal using its SIM card.

Base Station Subsystem(BSS)

The BSS connects the Mobile Station and the NSS. It is in charge of the transmission and reception. The BSS can be divided into two parts:

The Base Transceiver Station (BTS) or Base Station. The Base Station Controller (BSC).

Base Transceiver StationBase Transceiver Station(BTS)(BTS)

The BTS controls the radio interface to the MS. The BTS comprises the radio equipment such as transceivers and antennas which are needed to serve each cell of the network. A BTS is usually placed in the centre of a cell. Its transmitting power defines the size of a cell. Each BTS has between one and sixteen transceivers depending on the density of users in the cell.

The Base Station ControllerThe Base Station Controller(BSC)(BSC)

The BSC controls a group of BTS and manages their radio resources. A BSC is principally in charge of handovers, frequency hopping, exchange functions and control of the radio frequency power levels of the BTS.


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Network and Switching Subsystem(NSS)Network and Switching Subsystem(NSS)

The switching system (SS) is responsible for performing call processing and subscriber-related functions. The different components of the NSS are described below:

Mobile services Switching Centre(MSCMobile services Switching Centre(MSC)

The MSC performs the telephony switching functions for the mobile network. It controls calls to and from other telephone and data systems such as Public Switched Telephone Network(PSTN),Integrated Services Digital Network(ISDN),public data networks,private networks and other mobile networks.

Home Location Register (HLR)Home Location Register (HLR)

The HLR is a centralized network database that stores and manages all mobile subscriptions belonging to a specific operator. It acts as a permanent store for a person’s subscription information until that subscription is canceled. The information stored includes:

Subscriber identity Subscriber supplementary services Subscriber location information Subscriber authentication information

If the capacity of a HLR is exceeded by the number of subscribers, additional HLRs may be added.

Visitor Location Register (VLR)Visitor Location Register (VLR)

The VLR database contains information about all the mobile subscribers currently located in the MSC service area. Thus, there is one VLR for each MSC in a network. The VLR temporarily stores subscription information so that the MSC can service all the subscribers currently visiting that MSC service area. The VLR can be regarded as a distributed HLR as it holds a copy of the HLR information stored about the subscriber.When a subscriber roams into a new MSC service area, the VLR connected to that MSC requests information about the subscriber from the subscriber’s HLR. The HLR sends a copy of the information to the VLR and updates its own location information. When the subscriber makes a call, the VLR will already have the information required for call set-up.

AUthentication Center (AUC)AUthentication Center (AUC)

AUC provides authentication and encryption parameters that verify the user's identity and ensure the confidentiality of each call. The AUC protects network operators from different types of fraud found in today's cellular world. The AUC


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is a database connected to the HLR which provides it with the authentication parameters and ciphering keys used to ensure network security.

Equipment Identity Register (EIR)Equipment Identity Register (EIR)

The EIR is also used for security purposes. It is a register containing information about the mobile equipments. More particularly, it contains a list of all valid terminals. A terminal is identified by its International Mobile Equipment Identity (IMEI). The EIR allows then to forbid calls from stolen or unauthorized terminals (e.g., a terminal which does not respect the specifications concerning the output RF power).

The Operation and Support Subsystem (OSS)The Operation and Support Subsystem (OSS)

The OSS is connected to the different components of the NSS and to the BSC, in order to control and monitor the GSM system. It is also in charge of controlling the traffic load of the BSS. However, the increasing number of base stations, due to the development of cellular radio networks, has provoked that some of the maintenance tasks are transferred to the BTS. This transfer decreases considerably the costs of the maintenance of the system.

FREQUENCY BAND OF OPERATION


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Frequency bands are allocated on the GSM Band first come first serve basis for first three operations in a state 900 brands for next three operations 1800 band & for further next three operators 1800 band is allotted .

Frequency bands allotted to Airtel in North regionIn Punjab 900 bandIn Haryana 1800 bandIn Rajastan 900 bandIn HP 900 bandIn J&K 900 band

RADIO CHANNEL

A mobile station communicates with a base station via a radio channel. A radio channel is a bi-directional radio transmission path. Each radio channel has two distinct frequencies; one for downlink and one for uplink.

Downlink is defined as the transmission path from the base station to the mobile station, while uplink is defined as the transmission path from the mobile station to the base station.

Uplink and downlink on a radio channel

The base station transmits on one frequency while the mobile station transmits on another frequency. This creates a full duplex communication path. That is, simultaneous communication in both directions.

GSM 900GSM 900 GSM1800GSM1800 GSM 1900GSM 1900

Uplink frequencyUplink frequency 890-915 Mhz890-915 Mhz 1710-1785 Mhz1710-1785 Mhz 1850-1910 Mhz1850-1910 Mhz


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Downlink frequencyDownlink frequency 935-960 Mhz935-960 Mhz 1805-1880 Mhz1805-1880 Mhz 1930-1990 Mhz1930-1990 Mhz

DUPLEX DISTANCE

The distance between one uplink frequency and its corresponding downlink frequency is called the duplex distance. The duplex distance varies for different frequency bands.

STANDARD GSM 900 GSM 1800 GSM 1900

Duplex Distance 45 MHz 95 MHz 80 MHz

Duplex distance

CHANNEL SEPARATION

The distance between adjacent frequencies on either the uplink or downlink is called channel separation. Channel separation is 200 kHz, regardless of the standards mentioned above. This separation is necessary to reduce interference between channels.

In addition to the duplex distance, every mobile system includes a channel separation. This is the distance on the frequency band between channels being transmitted in the same direction. This is required in order to avoid the overlapping of information in one channel into an adjacent channel.The length of separation between two channels is dependent on the amount of information which is to be transmitted within the channel. The greater the amount of information to transmit, the greater the amount of separation required.


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From the figure above, it can be seen that the information to be sent is modulated around the carrier frequency of 895.4 MHz. The same is true of the information to be sent on 895.6 MHz. To avoid interference between the two sets of information, a separation distance of 200 kHz is required. If less separation were used, they would interfere and a caller on 895.4 MHz may experience crosstalk or noise from the caller on 895.6 MHz.

ACCESS METHOD

Ericsson has chosen the Time Division Multiple Access (TDMA) method for all Ericsson GSM networks. TDMA allows several different calls to share the same frequency.i.e TDMA is a technique in which several different calls may share the same carrier. Each call is assigned a particular time slot. Most digital cellular systems use the technique of Time Division Multiple Access (TDMA) to transmit and receive speech signals. With TDMA, one channel is used to carry a number of calls, each call using that channel at designated periods in time. These periods of time are referred to as time slots. Each MS on a call is assigned one time slot on the uplink frequency and one on the downlink frequency. The information sent during one time slot is called a burst. In GSM, a TDMA frame consists of 8 time slots. This means that a GSM radio carrier can carry 8 calls.

TDMA


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AIR INTERFACE CHANNELS :

The path used to carry information between a Mobile Station and a Base Transceiver Station is known as the Physical Channel. A physical channel may carry different messages, depending on the information which is to be sent. These messages are called logical channels. For example, on one of the physical channels used for traffic, the traffic itself is transmitted using a Traffic CHannel (TCH) message, while a handover instruction is transmitted using a Fast Associated Control Channel (FACCH) message.The Control and Traffic Channels are further subdivided, there are two types of Traffic Channels and three categories of Control

INTRODUCTION TO PHYSICAL AND LOGICAL CHANNELS

Each timeslot on a TDMA frame is called a physical channel. Therefore, there are 8 physical channels per carrier frequency in GSM. Physical channels can be used to transmit speech, data or signaling information.

Logical channels and bursts

CONTROL CHANNELS


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When an MS is switched on, it searches for a BTS to connect to. The MS scans the entire frequency band, or, optionally, uses a list containing the allocated carrier frequencies for this operator. When the MS finds the strongest carrier, it must then determine if it is a control channel. It does so by searching for a particular logical channel called Broadcast Control CHannel (BCCH).A frequency carrying BCCH contains important information for an MS, including e.g. the current LA identity, synchronization information and network identity. Without such information, an MS cannot work with a network. This information is broadcast at regular intervals, leading to the term Broadcast Channel (BCH) information.

Broadcast Channels (BCH)

The BCH channels are used by the base station to provide the mobile station with the sufficient information it needs to synchronize with the network. Three different types of BCHs are:

The Broadcast Control Channel (BCCH), which gives to the mobile station the parameters needed in order to identify and access the network.

The Synchronization Channel (SCH) , carries information about the TDMA frame number and the BASE STATION IDENTITY CODE of BTS.

The Frequency-Correction Channel (FCCH) , which supplies the mobile station with the frequency reference of the system in order to synchronize it with the network.

When the MS has finished analyzing the information on a BCH, it then has all the information required to work with a network. However, if the MS roams to another cell, it must repeat the process of reading FCCH, SCH and BCCH in the new cell. If the mobile subscriber then wishes to make or receive a call, the Common Control CHannels (CCCH) must be used.

Common Control Channels (CCCH)

The CCCH channels help to establish the calls from the mobile station or the

network. Three different types of CCCH can be defined:

The Paging Channel (PCH), is used to alert the mobile station of an incoming call.

The Random Access Channel (RACH) , which is used by the mobile station to request access to the network.

The Access Grant Channel (AGCH) is used by the base station to inform the mobile station about which channel it should use. This channel is the answer of a base station to a RACH from the mobile station


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At this stage the MS and BSS are ready to begin call set-up procedures. For this the MS and BSS use Dedicated Control CHannels (DCCHs).

Dedicated Control Channels (DCCH)

The DCCH channels are used for message exchange between several mobiles or a mobile and the network. Two different types of DCCH can be defined:

Standalone Dedicated Control Channel (SDCCH) , is used in order to exchange signaling information in the downlink and uplink directions.

Slow Associated Control Channel (SACCH) is used for channel maintenance and channel control.

Fast Associated Control Channels (FACCH) replaces all or part of a traffic channel when urgent signaling information must be transmitted. The FACCH channels carry the same information as the SDCCH channels.

Cell Broadcast Channel (CBCH this logical channel is used to transmit short message service

Traffic Channels

Once call set-up procedures have been completed on the control physical channel the MS tunes to a traffic physical channel. There are two types of TCH:

Full rate (TCH): transmits full rate speech (13 kbits/s). A full rate TCH occupies one physical channel.

Half rate (TCH/2) : transmits half rate speech (5.6 kbits/s). Two half rate TCHs can share one physical channel, thus doubling the capacity of a cell.

Enhanced Full rate (TCH): transmits full rate speech with an improved voice quality. It also occupies one physical channel.

Burst structure As it has been stated before, the burst is the unit in time of a TDMA system. Four different types of bursts can be distinguished in GSM:

The frequency-correction burst is used on the FCCH. It has the same length as the normal burst but a different structure.

The synchronization burst is used on the SCH. It has the same length as the normal burst but a different structure.

The random access burst is used on the RACH and is shorter than the normal burst.


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The normal burst is used to carry speech or data information. It lasts approximately 0.577 ms and has a length of 156.25 bits. Its structure is presented in figure 3.

Structure of the 26-Multiframe, the TDMA frame and the normal burst*This figure has been taken, with the corresponding authorization, from "An Overview of GSM" by John Scourias (see Other GSM sites) The tail bits (T) are a group of three bits set to zero and placed at the beginning and the end of a burst. They are used to cover the periods of ramping up and down of the mobile's power. The coded data bits corresponds to two groups, of 57 bits each, containing signaling or user data. The stealing flags (S) indicate, to the receiver, whether the information carried by a burst corresponds to traffic or signaling data. The training sequence has a length of 26 bits. It is used to synchronize the receiver with the incoming information, avoiding then the negative effects produced by a multipath propagation. The guard period (GP), with a length of 8.25 bits, is used to avoid a possible overlap of two mobiles during the ramping time.


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1.CALL FROM MS

Provided that the MS is listening to the system information in the cell and that it is registered in the MSC/VLR handling this cell, the MS can attempt to make a call. The procedures are 1. The MS requests a SDCCH using the RACH.2. The MS indicates that it wants to set up a call. The identity of the MS, IMSI, is analyzed and the MS is marked as busy in the VLR.3. Authentication is performed as described for location updating.4. Ciphering may be initiated.5. MSC receives a setup message from the MS. This information includes what kind of service the MS wants and the number (called the B number) dialed by the mobile subscriber. MSC checks that the MS does not have services like barring of outgoing calls activated. Barring can be activated either by the subscriber or by the operator. If the MS is not barred, the setup of the call proceeds.6. Between the MSC and the BSC a link is established and a PCM TS is seized. The MSC sends a request to the BSC to assign a TCH. The BSC checks if there is an idle TCH, assigns it to the call and tells the BTS to activate the channel. The BTS sends an acknowledgment when the activation is complete and then the BSC orders the MS to transfer to the TCH. The BSC informs the MSC when the assignment is complete. The traffic control subsystem analyses the digits and sets up the connection to the called subscriber. The call is connected through in the group switch. 7. An alert message is sent to the MS indicating that a ringing tone has been generated on the other side. The ringing tone generated in the exchange on the B subscriber side is sent to the MS via the group switch in MSC. The ringing tone issent over the air, not generated in the MS.8. When the B subscriber answers, the network sends a connect message to the MS indicating that the call is accepted. The MS returns a connect acknowledgment, which completes the call set-up.


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Fig:Mobile originating call establishment.

Figure shows the messages sent between the MS and thenetwork during mobile originating call set-up.


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Fig.: Mobile originating call establishment (early assignment).

2.CALL TO MS

A mobile terminated call is more complicated than a mobile originated call. This is due to the fact that the calling party does not know where the MS (called party) is located. The signaling is shown in Figure1. The number dialed by the calling part is called the Mobile Station ISDN number (MSISDN). In cases where a call is made from the fixed network, PSTN, the exchange analyses the number and determines that the call is for a GSM subscriber.2. The call is routed to the nearest GMSC in the home PLMN of the called MS.3. By analyzing the MSISDN, the GMSC finds out which HLR the subscriber is registered in. GMSC asks the HLR for information so the call can be routed to the MSC/VLR where the MS is temporary registered. With help of MSISDN the HLR finds the IMSI and the data record for the subscriber. IMSI is a number for the subscriber (see Appendix), only used in the signaling network. The address to the serving VLR was received at registration and is stored together with IMSI in the HLR.4. The HLR contacts the VLR to get a roaming number. This is an ordinary telephone number to the MSC/VLR. The VLR sends the roaming number to the HLR.5. The HLR forwards the roaming number to the GMSC.6a. With help of the roaming number, the GMSC can route the call to the appropriate MSC.


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6b. The call is routed to the MSC. If the system has the feature ‘Call Dropback’, and this feature is supported by the national signaling scheme, the GMSC may drop the call ‘back’ to the previous node. The decision is based on the received roaming number and the capabilities of the incoming route. Then, the routes marked(2) and (6a) are released.

Fig : Call from PSTN

In some situations, PSTN may be used to reroute the call. In countries having a poorly functioning or very expensive PSTN, it might be better to build a separate network with connections between the MSCs and GMSCs.7. The MSC knows which location area the MS is located in and sends a paging message to the BSCs handling this location area. In GSM, there are two places where information about which cells belong to the location area can be stored:

the MSC the BSC

In Ericsson’s GSM system it is the BSC that stores this information. The MSC sends the identity of the location area and MS to the BSCs in the LA.8. The BSC distributes the paging message to the BTSs in the LA.9. The BTSs page the MS using IMSI or TMSI. The MS sends a request for a SDCCH when it detects its identity in the paging message. The MSC performs authentication and starts ciphering as described earlier. The MSC may send information to the MS about the services that are requested. These can for example be speech, data, fax. The BSC orders the BTS to activate a TCH and to release the SDCCH. MS is ordered to tune in the frequency of the TCH. An


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Alerting message is sent from the MS indicating that a ringing tone has been generated in the MS. A ringing tone for the calling subscriber is generated in MSC. When the mobile subscriber answers, the MS sends a Connect message. The network completes the through connection path and sends a Connection acknowledgment to MS. The duplex path for traffic is now open.

Fig : Mobile terminating call establishment


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TRANSMISSION RATE

The transmission rate over the air is 270 kbits/s. This is true for GSM 900, GSM 1800 and GSM 1900. The amount of information transmitted over a radio channel over a period of time is known as the transmission rate. Transmission rate is expressed in bits per second or bit/s.

TRANSMISSION PROBLEMS:Many problems may occur during the transmission of radio signal.They are:

1. PATH LOSS Path loss occurs when the received signal becomes weaker & weaker due to increasing distance between MS and BTS,even if there are no obstacles between the Tx & Rx antenna.

2. SHADOWING Shadowing occurs when there are physical obstacles including hills & buildings between the BTS & MS.The obstacles create a shadowing effect which can decrease the received signal strength.When the MS moves,the signal strength fluctuates depending on the obstacles between the MS & BTS.

Shadowing

3. MULTIPATH FADING This occurs when there is more than one transmission path to the MS & BTS,& therefore more than one signal arriving at the receiver.This may be due to buildings or mountains,either close to or far from the receiving device.Rayleigh fading & Time dispersion are forms of multipath fading.

3.1 Rayleigh fading

This occurs when a signal takes more than one path between the MS & BTS antennas.In this case,the signal is not received on the line of sight path directly


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from the Tx antenna,rather it is reflected off buildings & is received from several different paths.It occurs when the obstacles are close to the Rx antenna.

Rayleigh fading

3.2 Time dispersion

Time dispersion is another problem relating to multiple paths to the Rx antenna of either an MS or BTS.However,in contrast to rayleigh fading,the reflected signal comes from an object far away from the Rx antenna.It causes Inter Symbol Interference(ISI) where consecutive bits interfere with each other making it difficult for the Rx to determine which symbol is the correct one.An example of this is shown in the figure below where the sequence 1,0 is sent from the BTS


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Time dispersionIf the reflected signal arrives one bit time after the direct signal, then the receiver detects a 1 from the reflected wave at the same time it detects a 0 from the direct wave. The symbol 1 interferes with the symbol 0 and the MS does not know which one is correct.

4. TIME ALIGNMENTEach MS on a call is allocated a time slot on a TDMA frame.This is an amount of time during which the MS transmits information to the BTS.The information must also arrive at the BTS within that time slot.The time alignment problem occurs when part of the information transmitted by an MS does not arrive within the allocated time slot.Instead,that part may arrive during the next time slot,& may interfere with information from another MS using that other time slot.It is caused by a large distance between the MS & the BTS.Effectively,the signal cannot travel over the large distance within the given time.For example, an MS is close to a BTS and has been allocated time slot 3 (TS 3). During the call, the MS moves away from the BTS causing the information sent from the BTS to arrive at the MS later and later. The answer from the MS also arrives later at the BTS. If nothing is done, the delay becomes so long that thetransmission from the MS in time slot 3 overlaps with the information which the BTS receives in time slot 4.

The time alignment problem

1.CHANNEL CODINGIn digital transmission,the quality of the transmitted signal is often expressed in terms of how many of the received bits are incorrect.This is called Bit Error Rate(BER).BER defines the % of the total no. of received bits which are incorrectly detected.This % should be as low as possible.


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This percentage should be as low as possible. It is not possible to reduce the percentage to zero because the transmission path is constantly changing. This means that there must be an allowance for a certain amount of errors and at the same time an ability to restore the information, or at least detect errors so the incorrect information bits are not interpreted as correct. This is especially important during transmission of data, as opposed to speech, for which a higher BER is acceptable.Channel coding is used to detect & correct errors in a received bit stream.It adds bits to the message.These bits enable a channel decoder to determine whether the message has faulty bits,& to potentially correct the faulty bits.

2.INTERLEAVING In reality, bit errors often occur in sequence, as caused by long fading dips affecting several consecutive bits. Channel coding is most effective in detecting and correcting single errors and short error sequences. It is not suitable for handling longer sequences of bit errors. For this reason, a process called interleaving is used to separate consecutive bits of a message so that these are transmitted in a non-consecutive way. For example, a message block may consist of four bits (1234). If four message blocks must be transmitted, and one is lost in transmission, without interleaving there is a 25% BER overall, but a 100% BER for that lost message block. It is not possible to recover from this.

Interleaving If interleaving is used the bits of each block may be sent in a non-consecutive manner. If one block is lost in transmission, again there is a 25% BER overall. However, this time the 25% is spread over the entire set of message blocks, giving a 25% BER for each. This is more manageable and there is a greater possibility that the errors can be corrected by a channel decoder.


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Received interleaved message blocks

3.TIMING ADVANCEThis is a solution specifically designed to counteract the problem of time alignment.It works by instructing the misaligned MS to transmit its burst earlier than it normally would.In GSM,the timing advance information relates to bit times.Thus an MS may be instructed to advance its transmission by a certain no. of bit times.The maximum in GSM is 63 bit times. Timing advance is a solution specifically designed to counteract the problem of time alignment. It works by instructing the misaligned MS to transmit its burst earlier than it normally would. In GSM, the timing advance information relates to bit times. Thus, an MS may be instructed to advance its transmission by a certain number of bit times. The maximum in GSM is 63 bit times. This is one of the parameters that limits the GSM cell size to a maximum of 35 km radius.

Timing advance

INTRODUCTION TO ANALOG AND DIGITAL

Analog Information

Analog information is continuous and does not stop at discrete values. An example of analog information is time. It is continuous and does not stop at specific points. An analog watch may have a second-hand which does not jump from one second to the next, but continues around the watch face without stopping.

Analog Signals


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An analog signal is a continuous waveform which changes in accordance with the properties of the information being represented.

Digital Information

Digital information is a set of discrete values. Time can also be represented digitally. However, digital time would be represented by a watch which jumps from one minute to the next without stopping at the seconds. In effect, such a digital watch is taking a sample of time at predefined intervals.

Digital Signals

For mobile systems, digital signals may be considered to be sets of discrete waveforms.

DIGITAL SIGNAL

ADVANTAGES OF USING DIGITAL

Human speech is a form of analog information. It is continuous and changes in both frequency (higher and lower pitches) and amplitude (whispering and shouting). At first, analog signals may appear to be a better medium for carrying analog information such as speech. Analog information is continuous and if it were to be represented by discrete samples of the information (digital signal), then some information would be missing (like the seconds on the digital watch). An analog signal would not miss any values as it too is continuous. All signals, analog and digital, become distorted over distances.In analog, the only solution to this is to amplify the signal. However, in doing so, the distortion is also amplified. In digital, the signal can be completely regenerated as new, without the distortion.


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The problem with using digital signals to transfer analog information is that some information will be missing due to the technique of taking samples. However, the more often the samples are taken, the closer the resulting digital values will be to a true representation of the analog information. Overall, if samples are taken often enough, digital signals provide a better quality for transmission of analog information than analog signals.

ADVANTAGES OF DIGITAL TRANSMISSION It economizes on Bandwidth. It allows easy integration with Personnal communication Systems(PCS)

devices. It maintains superior Quality of Voice transmission over long distances. It is difficult to Decode. It can use Lower Average transmitted power. It enables smaller and less expensive individual recievers and

transmitters. It offers Voice privacy.

The following figure summarizes the GSM transmission process. The details of transmission from an MS are described later in this section.


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GSM transmission process

Stage 1 ANALOG TO DIGITAL (A/D) CONVERSION

One of the primary functions of an MS is to convert the analog speech information into digital form for transmission using a digital signal. The analog to digital (A/D) conversion process outputs a collection of bits: binary ones and zeros which represent the speech input.

A/D CONVERSION


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The A/D conversion is performed by using a process called Pulse Code Modulation (PCM). PCM involves three main steps:

Sampling Quantization Coding

Step 1: SAMPLING

Sampling involves measuring the analog signal at specific time intervals.

Analog signal sampling

The accuracy of describing the analog signal in digital terms depends on how often the analog signal is sampled, among other things. This is expressed as the sampling frequency. The sampling theory states that: To reproduce an analog signal without distortion , the signal must be sampled with at least twice the frequency of the highest frequency component in the analog signal.Normal speech mainly contains frequency components lower than 3400 Hz. Higher components have low energy and may be omitted without affecting the speech quality much. Applying the sampling theory to analog speech signals, the sampling frequency, should be at least 2 x 3.4 kHz = 6.8 kHz. Telecommunication systems use a sampling frequency of 8 kHz, which is acceptable based on the sampling theory.Step 2: Quantization

The next step is to give each sample a value. For this reason, the amplitude of the signal at the time of sampling is measured and approximated to one of a finite set of values. The figure below shows the principle of quantization applied to an analog signal. It can be seen that a slight error is introduced in this process when the signal is quantized or approximated. The degree of accuracy depends on the number of quantization levels used. Within common telephony, 256 levels are used while in GSM 8,192 levels are used.


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Quantization

Step 3: Coding

Coding involves converting the quantized values into binary. Every value is represented by a binary code of 13 bits (213= 8192). For example, a quantized value of 2,157 would have a bit pattern of 0100001101101:

Coding of quantized value 2157

Summary of A/D Conversion

The result from the process of A/D conversion is 8,000 samples per second of 13 bits each. This is a bit rate of 104 kbits/s. When it is considered that 8 subscribers use one radio channel, the overall bit rate would be 8 x 104 kbits/s = 832 kbits/s. Recalling the general rule of 1 bit per Hertz, this bit rate would not fit into the 200 kHz available for all 8 subscribers. The bit rate must be reduced somehow - this is achieved using segmentation and speech coding.

STAGE 2: SEGMENTATION The key to reducing the bit rate is to send information about the speech instead of the speech itself. This can be explained with the following analogy: Person A wishes to listen to a certain piece of music and they know that person B has it on record. A rings B asking for the use of the record for some time. Unfortunately, the record is scratched and cannot be used. Instead, B sends A parameters of how the music is built up - the sheets of music - together with


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information about how fast it should be played - the frequency - and A reproduces the music. In GSM, the speech coding process analyzes speech samples and outputs parameters of what the speech consists of: the tone, length of tone, pitch, etc. This is then transmitted through the network to another MS which generates the speech based on these parameters.The process of segmentation and speech coding is explained in more detail as follows:The human speech process starts in the vocal chords or speech organs, where a tone is generated. The mouth, tongue, teeth, etc. act as a filter, changing the nature of this tone. The aim of speech coding in GSM is to send only information about the original tone itself and about the filter. Segmentation: Given that the speech organs are relatively slow in adapting to changes, the filter parameters representing the speech organs are approximately constant during 20 ms. For this reason, when coding speech in GSM, a block of 20 ms is coded into one set of bits. In effect, it is similar to sampling speech at a rate of 50 times per second instead of the 8,000 used by A/D conversion.

STAGE 3: SPEECH CODING

Instead of using 13 bits per sample as in A/D conversion, GSM speech coding uses 260 bits. This calculates as 50 x 260 = 13 kbits/s. This provides a speech quality which is acceptable for mobile telephony and comparable with wireline PSTN phones.Many types of speech coders are available. Some offer better speech quality, at the expense of a higher bit rate (waveform coders). Others use lower bit rates, at the expense of lower speech quality (vocoders). The hybrid coder which GSM uses provides good speech quality with a relatively low bit rate, at the expense of speech coder complexity.

Summary of Segmentation and Speech Coding

The GSM speech coder produces a bit rate of 13 kbits/s per subscriber. When it is considered that 8 subscribers use one radio channel, the overall bit rate would be 8 x 13 kbits/s = 104 kbits/s. This compares favorably with the 832 kbits/s from A/D conversion.


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However, speech coding does not consider the problems which may be encountered on the radio transmission path. The next stages in the transmission process, channel coding and interleaving, help to overcome these problems.

STAGE 4: CHANNEL CODING

Channel coding in GSM uses the 260 bits from speech coding as an input and outputs 456 encoded bits.The 260 bits are split according to their relative importance:

Block 1: 50 very important bits Block 2: 132 important bits and Block 3: 78 not so important bits

The first block of 50 bits is sent through a block coder, which adds three parity bits to result in 53 bits. It is these three bits which are used to detect errors in a received message.These 53 bits, the 132 bits in the second block and 4 tail bits (total = 189) are sent to a 1:2 convolutional coder which outputs 378 bits. The bits added by the convolutional coder enable the correction of errors when the message is received.The remaining bits of block 3 are not protected.

Channel coding

STAGE 5: INTERLEAVING

First level of interleaving

The channel coder provides 456 bits for every 20 ms of speech. These are interleaved, forming eight blocks of 57 bits each, as shown in the figure below.


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Interleaving of 20 ms of encoded speech

As can be seen in Figure , in any one burst, there is space for two of these blocks. (The remaining bits are explained later in this book.) Thus, if one burst transmission is lost, there is a 25% BER for the entire 20 ms of speech (2/8 = 25%).

Normal burst

Second level of interleaving

If only one level of interleaving is used, a loss of this burst results in a total loss of 25%. This is too much for the channel decoder to correct. A second level of interleaving can be introduced to further reduce the possible BER to 12.5%. Instead of sending two blocks of 57 bits from the same 20 ms of speech within one burst, a block from one 20 ms and a block from another 20 ms are sent together. This causes a delay in the system, because the MS must wait for the next 20 ms of speech. However, the system can now afford to loose a whole burst because the loss only affects 12.5% of the bits from each speech frame. This rate can be corrected by a channel decoder.

Speech frame


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Second level of interleaving

STAGE 6: CIPHERING/ENCRYPTION

The purpose of ciphering is to encode the burst so that it cannot be interpreted by any device other than the intended receiver. The ciphering algorithm in GSM is called the A5 algorithm. It does not add bits to the burst, meaning that the input and output to the ciphering process is the same as the input: 456 bits per 20 ms.

STAGE 7: BURST FORMATTING

As previously explained, every transmission from an MS/BTS must include some extra information such as the training sequence. The process of burst formatting is to add these bits (along with some others such as tail bits) to the basic speech/data being sent. This increases the overall bit rate, but is necessary to counteract problems encountered on the radio path. In GSM, the input to burst formatting is the 456 bits received from ciphering. Burst formatting adds a total of 136 bits per block of 20 ms, bringing the overall total to 592. However, each time slot on a TDMA frame is 0.577 ms long. This provides enough time for 156.25 bits to be transmitted (each bit takes 3.7 ms), but a burst only contains 148 bits. The rest of the space, 8.25 bit times, is empty and is called the Guard Period (GP). This time is used to enable the MS/BTS “ramp up” and “ramp down”. To ramp up means to get power from the battery/power supply


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for transmission. Ramping down is performed after each transmission to ensure that the MS is not using battery power during time slots allocated to other MSs. The output of burst formatting is a burst of 156.25 bits or 625 bits per 20 ms. However, in order to regulate the modulator, some dummy bits are used on either side of the burst. This brings the total to 676 bits per 20 ms of speech. When it is considered that there are 8 subscriber per TDMA frame, the overall bit rate for GSM can be calculated to be 270.4 kbits/s.

STAGE 8: MODULATION & TRANSMISSION

The transmission rate over the air is 270 kbits/s. This is true for GSM 900, GSM 1800 and GSM 1900. The amount of information transmitted over a radio channel over a period of time is known as the transmission rate. Transmission rate is expressed in bits per second or bit/s.

The 676 bits per 20 ms of speech must then be sent over the air using a carrier frequency. As previously explained, GSM uses the GMSK modulation technique. The bits are modulated onto a carrier frequency (e.g. 912.2 MHz) and transmitted.


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Network identities are numbers which a GSM network uses to locate a mobile subscriber when it is establishing a call to that subscriber. As the network relies on these identities to route calls to subscribers, it is important that each identity is unique and correct.

SUBSCRIBER-RELATED IDENTITIES

1.Mobile Station ISDN number (MSISDN) The Mobile Station ISDN number (MSISDN) uniquely identifies a mobile telephone subscription in the PSTN numbering plan. This is the number dialed when calling a mobile subscriber. As the MSISDN is the actual telephone number of the mobile subscriber, it is the only network identity that subscribers are aware of. All other network identities discussed in this chapter are for internal network use and subscribers do not need to be aware of them. MSISDN = CC + NDC + SN

CC = Country CodeNDC = National Destination CodeSN = Subscriber Number

2.International Mobile Subscriber Identity (IMSI) The International Mobile Subscriber Identity (IMSI) is a unique identity allocated to each subscriber which facilitates correct subscriber identification over the radio path and through the network. It is used for all signaling in the PLMN. All network related subscriber information is connected to an IMSI. The IMSI is stored in the SIM, the HLR and in the serving VLR.

The IMSI consists of three different parts:


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MCC Mobile Country CodeMNC Mobile Network CodeMSIN Mobile Station Identification NumberAccording to the GSM specifications, the IMSI has a maximum length of 15 digits.

Temporary Mobile Subscriber Identity (TMSI) The Temporary Mobile Subscriber Identity (TMSI) is a temporary IMSI number made known to an MS at registration. It is used to protect the subscriber’s identity on the air interface. The TMSI has local significance only (that is, within the MSC/VLR area) and is changed at time intervals or when certain events occur such as location updating. The TMSI structure can be determined by each operator but should not consist of more than 8 digits.

EQUIPMENT-RELATED IDENTITIES

1. International Mobile Equipment Identity (IMEI) The International Mobile Equipment Identity (IMEI) is used to uniquely identify MS equipment to the network. The IMEI is used for security procedures such as identifying stolen equipment and preventing unauthorized access to the network.According to the GSM specifications, IMEI has a total length of 15 digits, and consists of the following:

TAC Type Approval Code, determined by a central GSM bodyFAC Final Assembly Code, identifies the manufacturerSNR Serial Number, an individual serial number of six digits uniquely identifies all equipment within each TAC and FACspare A spare digit for future use and should always be zero when transmitt

International Mobile Equipment Identity and Software Version number(IMEISV)


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The International Mobile Equipment Identity and Software Version number (IMEISV) provides a unique identity for every MS and also refers to the version of software which is installed in the MS. The version of software is important as it may affect the services offered by the MS or its speech coding capabilities. For example, mobile networks need to know the MS speech coding capabilities when a call is being made (i.e. half rate/fullrate, etc). This will be indicated by the IMEISV. The IMEISV consists of the following:

SVN Software Version Number, allows the mobile equipment manufacturer to identify different software versions of a given type approved mobile. SVN value 99 is reserved for future use

LOCATION-RELATED IDENTITIES

Mobile Station Roaming Number (MSRN)The Mobile Station Roaming Number (MSRN) is a temporary network identity which is assigned during the establishment of a call to a roaming subscriber. More information about the use of MSRN can be found in the "Traffic Cases" section later in thebook. The MSRN consists of three parts:

A MSRN is used during the call setup phase for mobile terminating calls. Each mobile terminating call enters the GMSC in the PLMN. The call is then re-routed by the GMSC, to the MSC where the called mobile subscriber is located. For this purpose, a unique number (MSRN) is allocated by the MSC and provided to the GMSC. The MSRN is seized for the call setup phase only and released immediately afterwards. The call setup takes place in the following way:1. GMSC receives a signaling message "Initial Address Message" for the incoming call (MSISDN).


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2. GMSC sends a signaling message "Send Routing Information" to the HLR where the subscriber data is stored (MSISDN).3. HLR uses MSISDN to find the subscriber data in the database. The Supplementary Service (Call forward unconditional not active) is verified. The VLR address thatcorresponds to the subscriber location and the IMSI are retrieved. HLR sends a signaling message "Provide Roaming Number" using the VLR address as the destination (IMSI).4. VLR having received the message, requests MSC to seize an idle MSRN and to associate it with the IMSI received. VLR sends back the result to the HLR (MSRN).5. HLR sends back the result to the GMSC (MSRN).6. GMSC uses MSRN to re-route the call to the MSC. MSC receives a signaling message "Initial Address Message" for the incoming call (MSRN). MSC performs digit analysis on the received MSRN. The result is "Mobile terminating". The MSC finds the association between the MSRN and the IMSI. The MSRN is released and the IMSI is used for the final establishment of the call.

The Use of MSRN:

The interrogation call routing function (request for a MSRN) is a part of the Mobile Application Part (MAP). All data exchanged between the GMSC-HLR-MSC/VLR for the purpose of interrogation is sent over the signaling network.

Location Area Identity (LAI)The Location Area Identity (LAI) is a temporary network identity which is also required for routing. The two main purposes of the LAI are:1. Paging, which is used to inform the MSC of the LA in which the MS is currently situated2. Location updating of mobile subscribers The LAI contains the following:


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LAC Location Area Code, the maximum length of LAC is 16 bits, enabling 65,536 different location areas to be defined in one PLMN

Cell Global Identity (CGI)The Cell Global Identity (CGI) is used for identifying individual cells within an LA. Cell identification is achieved by adding a Cell Identity (CI) to the LAI components. The CI has a maximum length of 16 bits. The CGI consists of:

Base Station Identity Code (BSIC)The Base Station Identity Code (BSIC) enables MSs to distinguish between different neighboring base stations. The BSIC consists of:

NCC Network Color Code (3 bits) identifies the PLMN.. NCC is primarily used to distinguish between operators on each side of a borderBCC Base Station Color Code (3 bits) identifies the Base Station to help distinguish between RBS using the same control frequencies

Location Number (LN)


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The Location Number (LN) is a number related to a certain geographical area, which the network operator specifies by “tying” the location numbers to cells, location areas, orMSC/VLR service areas. The LN is used to implement features like regional/localsubscription and geographical differentiated charging. The LN consists of the following:

LSP Locally Significant Part

Regional Subscription Zone Identity (RSZI)For each regional subscription, zones/regions need to be defined. This is achieved by using the Regional Subscription Zone Identity (RSZI). The RSZI consist of the following:

ZC The length of the Zone Code, is two octets

There are two basic types of services offered through GSM: telephony (also referred to as teleservices) and data (also referred to as bearer services). Telephony services are mainly voice services that provide subscribers with the complete capability (including necessary terminal equipment) to communicate with other subscribers. Data services provide the capacity necessary to transmit appropriate data signals between two access points creating an interface to the


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network. In addition to normal telephony and emergency calling, the following subscriber services are supported by GSM:

Dual-Tone Multifrequency (DTMF)-DTMF is a tone signaling scheme often used for various control purposes via the telephone network, such as remote control of an answering machine. GSM supports full-originating DTMF.

Facsimile Group III-GSM supports CCITT Group 3 facsimile. As standard fax machines are designed to be connected to a telephone using analog signals, a special fax converter connected to the exchange is used in the GSM system. This enables a GSM-connected fax to communicate with any analog fax in the network.

Short Message Services-A convenient facility of the GSM network is the short message service. A message consisting of a maximum of 160 alphanumeric characters can be sent to or from a mobile station. This service can be viewed as an advanced form of alphanumeric paging with a number of advantages. If the subscriber's mobile unit is powered off or has left the coverage area, the message is stored and offered back to the subscriber when the mobile is powered on or has reentered the coverage area of the network. This function ensures that the message will be received.

Cell Broadcast-A variation of the short message service is the cell broadcast facility. A message of a maximum of 93 characters can be broadcast to all mobile subscribers in a certain geographic area. Typical applications include traffic congestion warnings and reports on accidents.

Voice Mail-This service is actually an answering machine within the network, which is controlled by the subscriber. Calls can be forwarded to the subscriber's voice-mail box and the subscriber checks for messages via a personal security code.

Fax Mail-With this service, the subscriber can receive fax messages at any fax machine. The messages are stored in a service center from which they can be retrieved by the subscriber via a personal security code to the desired fax number.

SUPPLEMENTRY SERVICES

GSM supports a comprehensive set of supplementary services that can complement and support both telephony and data services. Supplementary services are defined by GSM and are characterized as revenue-generating features. A partial listing of supplementary services follows.


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Call Forwarding-This service gives the subscriber the ability to forward incoming calls to another number if the called mobile unit is not reachable, if it is busy, if there is no reply, or if call forwarding is allowed unconditionally.

Barring of Outgoing Calls-This service makes it possible for a mobile subscriber to prevent all outgoing calls.

Barring of Incoming Calls-This function allows the subscriber to prevent incoming calls. The following two conditions for incoming call barring exist: baring of all incoming calls and barring of incoming calls when roaming outside the home PLMN.

Advice of Charge (AOC)-The AoC service provides the mobile subscriber with an estimate of the call charges. There are two types of AoC information: one that provides the subscriber with an estimate of the bill and one that can be used for immediate charging purposes. AoC for data calls is provided on the basis of time measurements.

Call Hold-This service enables the subscriber to interrupt an ongoing call and then subsequently reestablish the call. The call hold service is only applicable to normal telephony.

Call Waiting-This service enables the mobile subscriber to be notified of an incoming call during a conversation. The subscriber can answer, reject, or ignore the incoming call. Call waiting is applicable to all GSM telecommunications services using a circuit-switched connection.

Multiparty Service-The multiparty service enables a mobile subscriber to establish a multiparty conversation-that is, a simultaneous conversation between three and six subscribers. This service is only applicable to normal telephony.

Calling Line Identification Presentation/Restriction-These services supply the called party with the integrated services digital network (ISDN) number of the calling party. The restriction service enables the calling party to restrict the presentation. The restriction overrides the presentation.

Closed User Groups (CUGs)-CUGs are generally comparable to a PBX. They are a group of subscribers who are capable of only calling themselves and certain numbers.

GPRS(General Packet Radio Service)-GPRS uses a packet-mode technique to transfer high-speed and low-speed data and signalling in an efficient manner. GPRS optimises the use of network and radio resources. Strict separation between the radio subsystem and network subsystem is


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maintained, allowing the network subsystem to be reused with other radio access technologies. GPRS does not mandate changes to an installed MSC base. New GPRS radio channels are defined, and the allocation of these channels is flexible: from 1 to 8 radio interface timeslots can be allocated per TDMA frame, timeslots are shared by the active users, and up and downlink are allocated separately. The radio interface resources can be shared dynamically between speech and data services as a function of service load and operator preference.


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NETWORK SWITCHING SUB SYSTEM :

NSS forms the core of all the technical departments with the maintenance & working of all the MSC functions. NSS functions are divided into four sub departments :

1. ROAMING:

Roaming deals with the mobile roaming facility of the MS, which is the major facility provided to the mobile subscribers. It deals with the national & international launches, roaming related definitions, problems. It also deals with the SMS functioning within other networks too.


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2. VAS (VALUE ADDED SERVICES) :-

Various services like Floritel, news, cricket update are the services provided to the mobile users. VAS team deals with maintenance & upgrade of the system. It deals with the creation of new dialog boxes etc.

3. HARDWARE TEAM :-

It deals with the maintenance of all the MSC’s, RBSC’s, Ater’s & various Links etc. they monitor & rectify all the hardware alarms & also the responsible for their gradation.

4. IN ( INTELLIGENCE NETWORK ) TEAM :-

IN is the latest technology for prepaid subscribers. We have a new IN of Ericsson i.e. IN 3.6 and the maintenance & execution of the IN databases & all the prepaid related complaints. They are responsible for the IVR, recharges etc.

The Network Switching and Subsystem (NSS) in GSM systems consist of following components:

MOBILE SERVICES SWITCHING CENTER/VISITORLOCATION REGISTER (MSC/VLR)

MSC FUNCTIONS:The primary node in a GSM network is the MSC. It is the node which controls calls both to MSs and from MSs. The primary functions of an MSC include the following:


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o Switching and Call routing: an MSC controls call set-up, supervision and release and may interact with other nodes to successfully establish a call. This includes routing of calls from MSs to other networks such as a PSTN.

o Charging: an MSC contains functions for charging mobile calls and information about the particular charge rates to apply to a call at any given time or for a given destination. During a call it records this information and stores it after the call, e.g. for output to a billing center.

o Service provisioning: supplementary services are provided and managed by an MSC. In addition, the SMS service is handled by MSCs.

o Communication with HLRs: the primary occassion on which an MSC and HLR communicate is during the set-up of a call to an MS, when the HLR requests some routing information from the MSC.

o Communication with VLR: associated with each MSC is a VLR, with which it communicates for subscription information, especially during call set-up and release.

o Communication with MSCs: it may be necessary for two MSCs to communicate with each other during call set-up or handovers between cells belonging to different MSCs.

o Control of connected BSCs: as the BSS acts as the interface between the MSs and the SS, the MSC has the function of controlling the primary BSS node: the BSC. Each MSC may control many BSCs, depending on the volume of traffic in a particular MSC service area. An MSC may communicate with its BSCs during, for example, call set-up and handovers between two BSCs.

o Direct access to internet services: traditionally, an MSC accessed the Internet nodes of an Internet Service Provider (ISP) via existing networks such as the PSTN. However, this function enables an MSC to communicate directly with Internet nodes, thus reducing call set-up time. Direct access can be provided by using an access server called Tigris (from Advanced Computer Communications). This may be integrated in an MSC or stand-alone connected to an MSC.

VLR FUNCTIONS:The role of a VLR in a GSM network is to act as a temporary storage location for subscription information for MSs which are within a particular MSC service area. The VLR contains information from a subscriber's HLR necessary in order to provide the subscribed services to visiting users. When a subscriber enters the covering area of a new MSC, the VLR associated to this MSC will request information about the new subscriber to its corresponding HLR. The VLR will then have enough information in order to assure the subscribed services without needing to ask the HLR each time a communication is established.The VLR is always implemented together with a MSC; so the area under control of the MSC is also the area under control of the VLR. Thus, there is one VLR for each MSC service area. This means that the MSC does not have


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to contact the HLR (which may be located in another country) every time the subscriber uses a service or changes its status.

The following occurs when MSs move into a new service area:1. The VLR checks its database to determine whether or not it has a record for the MS (based on the subscriber’s IMSI) 2. When the VLR finds no record for the MS, it sends a request to the subscriber’s HLR for a copy of the MS’s subscription3. The HLR passes the information to the VLR and updates its location information for the subscriber. The HLR instructs the old VLR to delete the information it has on the MS 4. The VLR stores its subscription information for the MS, including the latest location and status (idle)

Fig.:VLR-HLR interaction

For the duration which the MS is within in its MSC service area, a VLR contains a complete copy of the necessary subscription details, including the following information for each MS:

Identity numbers for the subscriber Supplementary service information (e.g. whether the subscriber has call

forwarding on busy activated or not) Activitiy of MS (e.g. idle) Current LA of MS

GATEWAY MSC (GMSC) FUNCTIONS:Gateway functionality enables an MSC to interrogate a HLR in order to route a mobile terminating call. It is not used in calls from MSs to any terminal other than another MS.For example, if a person connected to the PSTN wants to make a call to a GSM mobile subscriber, then the PSTN exchange will access the GSM network by first connecting the call to a GMSC. The GMSC requests call routing information from the HLR which provides information about which MSC/VLR to route the call to. The same is true of a call from an MS to another MS


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HOME LOCATION REGISTER (HLR) FUNCTIONS:The HLR is a centralized network database that stores and manages all mobile subscriptions belonging to a specific operator. It acts as a permanent store for a person’s subscription information until that subscription is cancelled. The information stored includes:Subscriber identity (i.e. IMSI, MSISDN)Subscriber supplementary servicesSubscriber location information (i.e. MSC service area)Subscriber authentication information

The primary functions of the HLR include:o Subscription database Management: as a database, the HLR must

be able to process data quickly in response to data retrieval and update requests from other network nodes. For this reason it acts as a database management system. Each subscriber record contains a substantial amount of parameters.

o Communication with MSCs: when setting up calls to an MS, it is necessary for the HLR to contact the MSC serving the MS for routing information.

o Communication with GMSCs: during call set-up to an MS, the GMSC requests MS location information from the HLR, which then provides this in the form of routing information. Also, if the subscriber is detached the HLR will inform the GMSC that there is no need to perform further routing of the call. By analyzing the IMSI, a GMSC knows which HLR to contact worldwide for that MS’s subscription.

o Communication with AUCs: before any activity involving change or use of susbcription information takes place, the HLR must retrieve new authentication parameters from an AUC.

o Communication with VLRs when an MS moves into a new MSC service area the VLR for that area requests information about the MS from the HLR of the subscriber. The HLR provides a copy of the subscription details, updates its MS location information and instructs the old VLR to delete the information it has about that MS. As the ILR acts as a VLR for AMPS subscribers, the HLR communicates with it in a similar way.

AUthentication Center (AUC) and Equipment Identity AUthentication Center (AUC) and Equipment Identity

Register (EIR)Register (EIR)

PLMN’s need a higher level of protection than traditional telephone networks.PLMN’s need a higher level of protection than traditional telephone networks. Therefore, to protect GSM systems, the following security functions have been defined:

o Subscriber Authentication: by performing authentication, the network ensures that no unauthorized users can access the network, including those which are attempting to impersonate others.


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o Radio information ciphering: the information sent between the network and an MS is ciphered. An MS can only decipher information intended for itself.

o Mobile equipment identification: because the subscriber and equipment are separate in GSM, it is necessary to have a separate authentication process for the MS equipment. This ensures, e.g. that a mobile terminal which has been stolen is not able to access the network.

o Subscriber identity confidentiality:during communication with an MS over a radio link, it is desireable that the real identity (IMSI) of the MS is not always transmitted. Instead a temporary identity (TMSI) can be used. This helps to avoid subscription fraud.

The AUC and EIR are involved in the first three of the above features, while the last is handled by MSC/VLRs

AUC FUNCTIONS:The primary function of an AUC is to provide information which is then used by an MSC/VLR to perform subscriber authentication and to establish ciphering procedures on the radio link between the network and MSs.The information provided is called a triplet and consists of:

1. A non predictable RANDom number (RAND)2. A Signed RESponse (SRES)3. A ciphering Key (Kc)

Provision of Triplets

At subscription time, each subscriber is assigned a subscriber authentication Key (Ki). Ki is stored in the AUC along with the subscriber’s IMSI. Both are used in the process of providing a triplet. The same Ki and IMSI are also stored in the SIM. In an AUC the following steps are carried out to produce one triplet:

1. A non-predictable random number, RAND, is generated2. RAND and Ki are used to calculate SRES and Kc, using twodifferent algorithms, A3 and A8 respectively3. RAND, SRES and Kc are delivered together to the HLR as a


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Fig.: Provision of triplets

Authentication Procedure:1. The MSC/VLR transmits the RAND to the MS.2. The MS uses RAND in the A3 and A8 algorithms to compute the SRES and Ki.3. The signature SRES is sent back to MSC/VLR which performs authentication, by checking whether the SRES from the MS and the SRES from the AUC match. If so, the subscriber is permitted to use the network. If not, the subscriber is barred from network access.

Fig: Authentication procedure

Authentication can be performed during:


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Each registration Each call setup attempt Location updating Before supplementary service activation and deactivation

There can be exceptions for subscribers belonging to other PLMNs.

Ciphering Procedure:Confidentiality means that user information and signaling exchanged between BTSs and MSs is not disclosed to unauthorized individuals, entities or processes.A ciphering sequence is produced using Kc and the TDMA frame number as inputs in the encryption algorithm A5. The purpose of this is to ensure privacy concerning user information (speech and data) as well as user related signaling elements.In order to test the ciphering procedure some sample of information must be used. For this purpose the actual ciphering mode command (M) is used.1. M and Kc are sent from the MSC/VLR to the BTS.2. M is forwarded to the MS.3. M is encrypted using Kc (calculated earlier with SRES in the authentication procedure) and the TDMA frame number which are fed through the encryption algorithm, A5.4. The encrypted message is sent to the BTS.5. Encrypted M is decrypted in the BTS using Kc, the TDMA frame number and the decryption algorithm, A5.6. If the decryption of M was successful, the ciphering mode completed message is sent to the MSC. All information over the air interface is ciphered from this point on.

Fig : Ciphering procedure


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EIR FUNCTIONS:

Equipment Identification Procedure:The equipment identification procedure uses the identity of the equipment itself (IMEI) to ensure that the MS terminal equipment is valid.1. The MSC/VLR requests the IMEI from the MS.2. MS sends IMEI to MSC.3. MSC/VLR sends IMEI to EIR.4. On reception of IMEI, the EIR examines three lists:– A white list containing all number series of all equipment identities that have been allocated in the different participating GSM countries.– A black list containing all equipment identities that have been barred.– A gray list (on operator level) containing faulty or non approved mobile equipment.5. The result is sent to MSC/VLR, which then decides whetheror not to allow network access for the terminal equipment.

Fig. Equipment identification

The decision to identify equipment remains with individual operators. GSM specifications recommend identification for each attempted call set-up.

MESSAGE CENTER (MC) FUNCTIONS:An MC may be added to a GSM network to provide one or more of the following messaging services:Voice mailFax mailShort Message Service (SMS) text messagesSMS Cell Broadcast (SMSCB) text messagesThese services can generate considerable revenue for a network operator, as they are becoming increasingly popular.

Voice Mail


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Voice mail ensures that all calls to a person can be completed, even when a person does not answer calls. A calling party can record a voice message for the subscriber they are calling.A subscriber can use their MS to select diversion to voice mail based on a particular event or status (e.g. busy, unreachable).The subscriber is informed that they have voice messages in their mailbox by means of either a short text message or phonecall from the network at regular intervals. If their MS is detached, this indication is sent when the subscriber next attaches to the network. The subscriber can then retrieve their voice mail messages at a later stage. Functions for storing voice messages over a longperiod also exist.

Fax MailFax mail operates similarly to voice mail. For MSs which support fax, a subscriber can set diversion for all or some fax calls to a fax mailbox. When the MS is next attached to the network, the network will deliver the fax message to a fax machine identified by the MS

SMSA short text message consists of up 160 alphanumeric characters, entered at a Short Message Entity (SME) such as an MS (using the keypad) or computer terminal.A short message always originates or terminates in a GSM network, meaning that a short message can not be sent between two SMEs residing outside a GSM network. The short message originator knows if the message delivery is successful or unsuccessful via notification. When a message is submitted, the deferred delivery option can be requested. This option makes it possible to specify the time the message is to be delivered.An MC which handles SMS messages is often referred to as an SMS Center (SMS-C). When a message is to be forwarded to an MS, the system must first determine where the MS is situated.As in ordinary voice traffic, a gateway requests the routing information. The gateway is called the SMS GMSC.Each short message is time stamped by the when it is submitted.A message is deleted once the delivery is successful or once the time specified in deferred delivery expires. When a message is buffered, the SMS-C regularly attempts to deliver the message, at intervals defined by the operator.

SMSCBThe SMSCB service enables a message of up to 93 alphanumeric characters to be delivered to all attached MSs in one cell. This may be useful for identifying key phone numbers in the cell’s area such as that of a hospital or police station.Alternatively, it may be used for advertising services within the cell (e.g. “Superfood Restaurant in this area at the junction of M8 and I33”).


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ROAMING TESTINGS

Roaming testings are carried out to check and make sure that services and parameters provided by the operator are working are within control i.e. Outroamer may be in any part of world service provider must be able to change/edit/create supplementary services as well as subscriber permanent data (like barring, reset, cfu etc).After the tests results are pass links are opened for operator according to the launch status i.e. Bilateral or Unilateral(Either Inroamer or Outroamer).

In Bilateral Launch Status, both HPLMN and VPLMN subscribers are authorized to latch on to the network.(Airtel Punjab Subscriber can latch on to CSL Hongkong network and CSL Hongkong Subscriber can latch on to Airtel Punjab Network)

In Unilateral- Inroamers case, only subscriber of other network can latch on to HPLMN (Only CSL Hongkong Subscriber can latch on to Airtel Punjab Network)

In Unilateral-Outroamers case,only subscriber of HPLMN can latch onto VPLMN (Only Airtel Punjab Subscriber can latch on to CSL Hongkong network).

Tests that are performed are based on the launch status i.e.Both way or only one side has to perform tests.Bilateral case both ends have to perform tests one by one.After defining IMSI and GT for the network operator tests that are performed are as follow :-

SHORT TEST (IR24 ) LONG TEST PREPAID TEST(IR 32)

Short test

Before the start of the test we have to note the TT File .

The command used is C:\>afpls -ls

All the time measurement are taken only after synchronizing the clock of the computer with that of the MSC.

The command used is caclp;

In Short testing the following tests are performed

CHECK THE CALL AND SMS STATUS


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First a call is made from the inroamer test sim on a bharti sim. Then as per the international format we note down MSISDN &IMSI for both MS(a) and MS(b).

The command used for getting the imsi is

Mgtrp:msisdn=xxxxxxxxxx;

Then using the command

Mgslp:imsi=xxxxxxxxxx,all;

We note down the services provided to the inroamer.

Then the following test cases are performed:

Originate a call from Bharti sim

Terminate a call from Bharti sim

Originate a sms from Bharti sim

Terminate a sms from Bharti sim

CALL TEST

MS1(A) CALLS MS2(A), BOTH ROAMED TO VPLMN (B)

Inroamer to inroamer call is made from the roaming test sim cards .As per the international format we have to note down MSISDN &IMSI for both MS(a) and MS(b).Then following timings are noted down:

Dail end up time of MS(a)

Alerting time on MS(b)

Time of perceived answer of call

Time of disconnecting the call

MESSAGE TEST

MOBILE ORIGINATED AND TERMINATED SHORT MESSAGE SERVIC

Inroamer to inroamer sms is made from the roaming test sim cards. MS(b) is switched off for this test.

Then following timings are noted down:

SMS send time

MS(b) ON time

SMS Receive time on MS(b)


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After completing the tests, the Ttfile is again noted down.

The command used is afpls -ls

Format of filling the tests is somewhat as follow for short test (IR24):

APPENDIX AMoU-IREG Stage 4 Test Results for Mobile Stations of PLMN(a) Roaming to PLMN(b)

A.1.1. NETWORK OPERATOR INFORMATIONHPLMN (a) VPLMN (b) Date of Tests Testing personnel PLMN(a)

Tel/Fax: Testing personnel PLMN(b)

Tel/Fax:

A 2.1.1. LOCATION UPDATE BY MS(A) IN VPLMN(B)

(a) VLR Record contents:MSISDNIMSI

Teleservices

Bearer Services

Supplementary Services

A 2.1.3. MS1(A) CALLS MS2(A), BOTH ROAMED TO VPLMN (B)

(a) MSISDN of originating MS (i.e.MS1(a)) (b) Number keyed into MS1(a) (c) Time of start of call (i.e. SEND key operation)(d) Delay between SEND key operation at MS1(a) and MS2(a) alerting *(e) Time of perceived answer of call hr/min/sec*(f) Chargable Call Duration (i.e. perceived answer until end of call. Duration must be 60sec or more.)(g) Quality of call [Excellent, Good, Fair, Poor, Bad] GOOD(h) Echo present ? NOIf Yes, to which MS ? [MS1(a) / MS2(a)]


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(i) Comments

A 2.3 SMS TEST RESULTSA 2.3.1 MOBILE ORIGINATED AND TERMINATED SHORT MESSAGE SERVICE

(a) MSISDN of MS1(a) (b) E164 address of HPLMN SMS - Service Centre(c ) Time of transmitting to SMS - Service Centre(d) MSISDN of MS2(a) (e) Time of switching on MS2(a) hr/min/sec(f) Time of receipt of SMS at MS2(a) hr/min/sec(g) Was message correctly received? yes

Test Sheet

Test Successful (YES/NO) Remark Location Update Yes OkOriginate a call from Bharti SIM Yes OkTerminate a call on Bharti SIM Yes OkOriginate SMS from Bharti SIM Yes OkTerminate SMS on Bharti SIM Yes Ok

LONG TEST

In LONG TEST all the tests performed in the short test are to be performed.

First the Short Test is performed as follows:

a) We note down the Ttfile.

b) RESETING- Erasing the previous location information of the subscriber,then the MS is switched OFF and ON.Expected event- MS should be able to location update again, if it happens test is PASS otherwise other tests are not performed before sorting out this problem.

c)Check the call and sms status.

d)Inroamer to inroamer CALL test.

e)Inroamer to inroamer SMS test.


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In addition to the Short test the following tests are performed:

i) PSTN CALL TEST

In this test the call is made from PSTN to MS(a)

Under this test three different cases are performed.

MS(a) is ON (responding to paging)

IMSI DETACH (TAKE BATTERY OFF WHILE PHONE IS SWITCH ON)

MS(a) SWITCHED OFF (no response to paging)

In all the above cases we note down the following:

1. Dail end up time of PSTN

2. Alerting time on MS(a)

3. Time of Start of Announcement

4. Language of Announcement

5. Time of End of Announcement

6. Text of Announcement

In Switched OFF case the announcement is of the Other operator.

In IMSI detach the announcement is of the HLPMN (i.e Airtel)

ii) SUPPLEMENTARY SERVICE TESTS

Under this test the following cases are performed:

a) Barring of all outgoing calls (BAOC):

In this test all the outgoing calls from the inroamer card are barred and the following observations are recorded:

i) Time of activation of BAOC.

ii) Call to 112 must be successful.

iii) Call to PSTN must not be successful.

iv) Time of deactivation of BAOC.

b) Barring of all outgoing international calls (BOIC)

In this test all the outgoing international calls from the inroamer card are barred and the following observations are recorded:

1.Time of activation of BOIC.


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2. A call to a PSTN no. in VPLMN is made and the following timings are noted down:

1.Dail end up time of MS(a)

2.Alerting time on PSTN

3.Time of perceived answer of call

4.Time of disconnecting the call

3.Call to number in HPLMN must not be successful.

4.Time of deactivation of BOIC.

c) Barring of all outgoing international calls except for Home Country (BOIC-EXHC)

In this test all the outgoing international calls except for the HPLMN from the inroamer card are barred and the following observations are recorded:

1.Time of activation of BOIC-EXHC.

2. A call to a PSTN no. in VPLMN is made and the following timings are noted down:

1.Dail end up time of MS(a)

2.Alerting time on PSTN

3.Time of perceived answer of call

4.Time of disconnecting the call

3.Call to PSTN in HPLMN must be successful.

4.Time of deactivation of BOIC-EXHC.

d) Barring of all incoming calls (BAIC):

In this test all the incoming calls from the inroamer card are barred and the following observations are recorded:

i) Time of activation of BAIC.

ii) Call from a PSTN is made and the timings are noted down as earlier.

iii) Time of deactivation of BAIC.

e) Call forwarding when not reachable(CFNRC)- IMSI DETATCH case

f) Call forwarding when not reachable(CFNRC)-SWITCH OFF case

g) Call forwarding when busy (CFB)


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h) Call forwarding when no reply (CFNRY)

In these tests call forwardings are activated.

Expected event- The service is not activated as thess cases are not applicable for an inroamer.

i)Call forwading Unconditional(CFU)

In this test all calls of roaming SIM are forwarded on Bharti SIM and the following observations are taken:

1. Dail end up time of MS(a)

2. Alerting time on forwarded MS

3. Time of perceived answer of call

4. Time of disconnecting the call

PREPAID TEST(IR 32)


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Before the start of the test we have to note the TT File .


All the time measurement are taken only after synchronizing the clock of the computer with that of the MSC.

The command used is caclp;

The format of the prepaid test is provided by the operator.The calls are then made according to the format.The prepaid test format of hutch kolkata is as shown:

After completing the tests, the Ttfile is again noted down.



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GT AND IMSI SERIES ANALYSIS

The mobile telephone International Mobile Subscriber Identity (IMSI) number series, which is used at traffic handling in the Mobile Services Switching Centre/Visitor Location Register (MSC/VLR) and in the Short Message Service-Gateway MSC (SMS-GMSC), is analysed and can give the following results: IMSI number series with analysis data found; or IMSI number series not found.The analysis is implemented by the use of analysis data tables. These tables are specified in this document.The analysis data is stored in two analysis tables: the operating table used for traffic handling, and the non-operating table used for changing the analysis. A change in the analysis tables is specified in the non-operating table. The tables are then switched to activate the change. After activation, the original table remains protected against changes during a specified protection period (PROTECTIONTIME). PROTECTIONTIME is an application-dependent parameter defined in block MNSAN(The Function Block MNSAN is a part of the subsystem MTS (Mobile Telephony Subsystem) in APT.Function Block MNSAN handles and analyses IMSI number series and stores associated analysis data.), whose range of values is 1 - 4320 minutes, with a default value of 1440 minutes (24 hours).

MOBILE TELEPHONY, IMSI NUMBER SERIES ANALYSIS, ZEROING, INITIATE

Command

MGIZI;

Function

The command zeroes the entire not operating table in the IMSI (International Mobile Subscriber Identity) number series analysis.The order remains after system restart.

MOBILE TELEPHONY, IMSI NUMBER SERIES ANALYSIS, COPY, INITIATE

Command

MGICI;

Function

The command orders the operating table for IMSI (International Mobile Subscriber Identity) number series analysis to be copied to the not operating table. Unprotected not operating table is zeroed.The order remains after system restart.

Example 1

MGICI;Copying of the operating table for IMSI number series analysisinto the not operating table is ordered.


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edw://alex?DT=om&CW=MNSAN&DO=AI2&FN=2_15518-CNT2191617Uen.A1.html




MOBILE TELEPHONY, IMSI NUMBER SERIES ANALYSIS, SPECIFICATION, END

Command

MGISE:IMSIS=imsis;

Parameters

IMSIS=imsis International mobile subscriber identity number series. Specifies IMSI number series which is to be set vacant. Max 15 decimal digits.

Function

The command is used to delete IMSI number series in theIMSI number series analysis not operating table.The order remains after system restart.

Mobile Telephony, IMSI Number Series Analysis Specification, Initiate

Command

MGISI:IMSIS=imsis[,M=m,NA=na][,ANRES=anres...];

ParametersANRES=anres Miscellaneous analysis result

Expressed as id[-num] where:

id Analysis result identifier

num Numerical value of analysis result

IMSIS=imsis International Mobile Subscriber Identity (IMSI) number seriesDigit string 1 - 15 digits

The specified number series cannot overlap an existing number series; that is, the specified number series cannot be the same as the beginning of an existing number series. In addition, the beginning of the specified number series cannot be the same as an existing number series.

M=m Modification of IMSI from the E.212 to the E.214 numbering plan


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Expressed as num-digits where:

num Number of digits to be deleted from the most significant positionNumeral 1 - 15

digits Digits to be added in the most significant positionDigit string 1 - 15 digits

NA=na Nature of address 3

National significant number4

International significant number

The default value is 4.

Function

This command initiates IMSI number series analysis data for a group of mobile subscribers that is to have a common analysis result.If parameters M and NA are specified, the following data is used during IMSI number analysis to address the Home Location Register (HLR) as a Global Title (GT) for the Signalling Connection Control Part (SCCP):

Modified IMSI number according to E.214 numbering plan Nature of address specified in the command Translation type 0 (determined by the system)

If parameters M and NA are not specified, the following data is used during IMSI number analysis to address the HLR as a GT for the SCCP:

Received IMSI number according to E.212 numbering plan International significant number nature of address Translation type defined by an application parameter in the Parameter

List of block MNSANThe order remains after system restart.

Example 1

MGISI:IMSIS=310120;

IMSI numbers starting with 310120 are analysed using the E.212 numbering plan, international significant number nature of address, and translation type from the Parameter List of block MNSAN to address the HLR as a GT for the SCCP.

Example 2

MGISI:IMSIS=24466,M=5-3585,NA=4;

IMSI numbers starting with 24466 are modified to replace the five most significant digits with the digits 3585 and then analysed using the E.214


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numbering plan, international significant number nature of address, and translation type 0.

MOBILE TELEPHONY, IMSI NUMBER SERIES ANALYSIS, ACTIVATION, INITIATE

Command

MGIAI[:TIME=time];

Parameters

TIME=time Specifies the time for activation of the changed analysis table. Expressed as hhmm where: hh is numeral 00-23, mm is numeral 00-59. If the parameter part is omitted, the operating and not operating table are changed immediately.

Function

The command initiates the changed, not operating, table to become operating.The previous used operating table will be saved during a protection period.After the protection period, new data for IMSI (International Mobile Subscriber Identity) number series analysis may be specified. At time ordered activation the protection period is counted from the indicated time. If parameter TIME is given then result printout MT IMSI NUMBER SERIES ANALYSIS ACTIVATED is printed, otherwise an answer printout EXECUTED is printed.The order remains after system restart.

Example 1

MGIAI;Switching of not operating and operating tables takesplace immediately.

Example 2

MGIAI:TIME=2240;Switching of not operating and operating tables takesplace at 22:40.

MOBILE TELEPHONY, IMSI NUMBER SERIES ANALYSIS, ACTIVATION, RESET

Command

MGIAR;

Function

The command orders a reset of the analysis to the previous table for analysis.If time initiated activation of the not operating table is ordered but not executed, the order is cancelled.The order remains after system restart.


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Example 1

MGIAR;Return to previously used table for IMSI number series analysis.

CCITT7, Global Title Series, Initiate

Command

C7GSI:TT=tt,NP=np,NA=na,NS=ns,GTRC=gtrc[,STATUS=status];

ParametersGTRC=gtrc Global Title (GT) routing case

GT routing case is a routing specification in the Signalling Connection Control Part (SCCP) network, identified by a number.Numeral 1 - 65534

NA=na Nature of address indicatorNumeral 0 - 127

NP=np Numbering planNumeral 0 - 14

NS=ns Number seriesDigit string 1 - 18 digits

Each digit is 0 - 9 or #10 - #15.

A maximum of 10 overdecadic digits is allowed.STATUS=statu

s Status of the GT series in the non-operating GT area at special situations OLD

The GT series in the non-operating area have not been modified since last executed or cancelled activation.

ZERO The GT series in the non-operating area have been zeroed

TT=tt Translation typeNumeral 0 - 254

Function

This command defines a GT series and associates it to a GT routing case in the non-operating GT area. GTs used in SCCP messages are translated in accordance with the GT routing case specified for the GT series in this command. This format applies to International Telecommunication Union (ITU) and Chinese protocols.A GT series represents all GTs which have the same translation. The GT series is made up of translation type, numbering plan, nature of address indicator, and a number series.


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If the first digits of the GT match a GT series during translation, the GT routing case specified for this GT series is the translation result for the GT.Parameter STATUS is only valid at first C7GSI command after activating or zeroing the non-operating GT area.The order remains after system restart.

CCITT7, Global Title Series, Print

Command

C7GSP:TT=tt,NP=np,NA=na,NS=ns;

ParametersNA=na Nature of address indicator

Numeral 0 - 127 NP=np Numbering plan

Numeral 0 - 14 NS=ns Number series

Digit string 1 - 18 digits

Each digit is 0 - 9 or #10 - #15.

A maximum of 10 overdecadic digits is allowed.

TT=tt Translation typeNumeral 0 - 254

Function

This command prints GT series data and the associated GT routing case. A GT series represents all GTs which have the same translation. The GT series is made up of translation type, numbering plan, nature of address indicator, and a number series.This format is valid for International Telecommunication Union (ITU) and Chinese protocols.

CCITT7, Global Title Routing Case, Print

CTGCP:GTRC=gtrc;

ParametersGTRC=gtr

c GT routing case

GT routing case is a routing specification in the Signalling Connection Control Part (SCCP) network identified by a number.Numeral 1 - 65534

ALL All defined global title routing cases


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Function

This command prints GT routing case data.The specified GT routing cases defined with the given primary SP or secondary SP, or both are printed.

Example 1

C7GCP:GTRC=5&7;

GT routing case data for GT routing cases 5 and 7 defined in the operating GT area is printed.

CCITT7, SCCP Network Configuration, Print

Format

C7NCP:SP=sp;SP=sp Signalling Point (SP)

Function

This command prints network configuration data for all SPs or a specific one in the SCCP network. The information about the remote SCCP availability is also given.

CCITT7, Global Title Area Activation, Reset

Command

C7TAR;

Function

This command resets the global title areas.The operating and non-operating global title area are formed by global title series and global title routing cases.If the protection period has not elapsed, the non-operating global title area will be switched with operating global title area back to the original state (before the activation command was executed). If the activation of a (non-operating) global title area is ordered but not yet executed, the activation is cancelled.The order remains after system restart.

Example 1

C7TAR;

The global title areas are reset.


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CCITT7, Global Title Area Activation, Initiate

Command

/ \ | / \| | |TIME=time[,STATUS=status] ||C7TAI|:+ +|; | |STATUS=status || | \ /| \ /

ParametersSTATUS=statu

s Status of the non-operating Global Title (GT) area at special situations OLD

The GT series in the non-operating area have not been modified since last executed or cancelled activation, or the GT series have been modified but the GT routing cases remain unchanged since last executed or cancelled activation.

ZERO The GT series in the non-operating area have been zeroed, or the GT series have been modified but the GT routing cases remain zeroed

TIME=time Time of activation

Specifies the time for activation of the non-operating GT area. If the parameter is omitted, the non-operating GT area is activated immediately.

Expressed as hhmm where:

hh HoursDigit string 00 - 23

mm MinutesDigit string 00 - 59

Function

This command initiates the activation of the non-operating GT area.The operating and non-operating GT area are formed by GT series and GT routing cases.The activation can be time activated or immediate. An activation of the backup non-operating GT area can be performed.Parameter STATUS is only valid when the status of the non-operating GT area is old or zero.


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The operating area prior to activation will become the backup protected non-operating area after activation.The order remains after system restart.

Example 1

C7TAI;

The activation of the non-operating GT area is initiated immediately.

HEALTH CHECK

Health check is performed on regular basis.It consist of three basic steps.They are:

Welcome SMS testing Call testing SMS testing Reach me cases

WELCOME SMS TESTINGWhenever a subscriber latches on to home network from the other network/area then Home network gives Welcome SMSs to the subscriber. Winback sms is the acknowledgment to the subscriber that you have logged off the preferred network (Airtel). Exactly the messages are as follows :-

Message ID Message Edit

Delete

__WEL_IN__Dear __HOMEOPERATOR__ subscriber. Airtel INA02 welcomes you to Punjab. Stay connected on Punjab's largest and the only 2.5 G network covering 255 towns.

Edit Delete

__WEL_AVV_NAT1__Airtel Punjab at ur Service. Dial 626 fr Cab, 604 fr Info, 602 fr FoodTel, 611 fr Travel Info, 630 fr Car Helpline & 603 fr CourierTel between 10am to 6 Pm

Edit Delete

__WEL_AVV_NAT2__Enjoy Airtel Anywhere payment service. Now make payments by cash or credit card at select Airtel showrooms anywhere in India. For assistance Dial 121.

Edit Delete

Pre_out __GREETING__,Dear Airtel Punjab Customer, AIRTEL wishes you a pleasent stay in __OPERATOR__. Edit Delete

In touch IntAirtel wishes you a pleasant stay in __VISITEDCOUNTRY__. You have logged into __OPERATOR__. Have a great Day!

Edit Delete

WinBack Dear Subscriber, u have logged out of AirTel. Pls select AirTel/INA 02 manually and enjoy the widest coverage Edit Delete

_wel avv nat 3_Congratulation ! Lucky number 2394 is the owner of a Diamond pendant . Next time it could be you. Dial 456 now to get your lucky number.

Edit Delete

WEL AVV NAT 3Airtel&American Express offer you superior forex rates & free gift*.if u are in Amritsar Contact 0183-2590640/visit Rajasansi Airport.Condition apply

Edit Delete

WEL_BACK_NAT Airtel Punjab welcomes you back home. Enjoy home tariffs beyond this Point Edit Delete


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http://10.0.16.28/admin/message.php?start_value=0&screen_no=&action=E&id=12










__WEL_AVV_NAT4__Punjab's only network supporting connectivity thru GPRS, Edge and Blackberry even while Roaming Stay connected on Airtel / INA02

Edit Delete

__WEL_AVV_NAT5_Dial 646 and Speak 2 Ur Service, Airtels exclusive Voice Recognition System. Jokes, Ringtones, MusiCards, Cricket, Movie Reviews & lots more

Edit Delete

__WEL_AVV_NAT6__Airtel & American Express offer you superior forex rates & free gift.if u are in Amritsar Contact 01832590640/visit Rajasansi Airport.Condition apply

Edit Delete

__WEL_AVV_NAT7__Stay connected on Punjab's largest and the only network supporting GPRS while Roaming absolutely free.

Edit Delete

The messages comes as they are given in the profile.the various settings of the welcome sms are done by loging on to nimbus server.Then according to the messages generated we fill the sheet given below:

CALL TESTING

In call testing following steps are performed:

i)MO (Mobile Originating) call from test sim to Airtel sim.ii)MT (Mobile Terminating) call to test sim from Airtel sim.

SMS TESTING

In SMS testing following steps are performed:

i)MO (Mobile Originating) sms from test sim to Airtel sim.ii)MT (Mobile Terminating) sms to test sim from Airtel sim.

REACH ME CASES

Under these cases the call forwardings are tested.Tests are done for :

CFU CFNRY CFB CFNRC

The above mentioned supplementary services are tested by forwarding a call to some other number as well as to the voicemail box.

NOTE:If all the SMS are being delivered then the Welcome SMS testing is Pass.

TROUBLESHOOTING WELCOME SMS PROBLEM

Tapping Server is the server which manage the delivery of the message. Tapping server is connected in parallel onto Point of interconnection of the media with


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the switch. Tapping server is so called because it simply taps the link for National/International messages .Currently the links tapped by thetapping server are 0NLDO, 1NLDO, 0HFCLJAL and 1HFCLJAL. Two links tapped are for NLDO and the other two are for HFCLJAL . These links are for delivering welcome SMS to the subscriber.

IP Address for Punjab Tapping server is 10.0.16.28IP Address for Haryana Tapping server is 10.0.24.28IP Address for Himachal Tapping server is 10.0.32.28

For trouble shooting the messages we log on to Telnet 10.0.16.28Sql> select* from active_roamers where msisdn=------------;This command gives the status of msisdn stated in the command .

If roamer is tapped by the tapping server then it will show active state.Then we give the next commandSql> select * from roamer where msisdn=------------;This will total no. of visits made by the roamer along with date corresponding date. This is to ensure that the Time for re- welcome sms has expired.

If the re-welcome sms time has not expired then welcome sms will not come but to check the working of server we delete the subscriber data from the tapping server, this will allow the server to send welcome sms , and the command used isSql> delete from active_roamers where msisdn=----------;Sql> delete from roamer where msisdn=-----------;

If then also sms is not being delivered then after confirming all connections OK we call the vendor.


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MMS,MASALA and GPRS DUMP

The log is created to take the MMS,GPRS and MASALA dump.This dump consists of the MSISDNs of all the subscribers who have the above mentioned services activated.These dumps are required by the Sales & Marketing, Finance and Customer Care departments.These logs are created by using the below mentioned commands.

Home Location Register, Access Point Name, Print

Format

Command / \ |/ \ | ||APN1=apn1[,APN2=apn2]| | |+ +[,MSUSERS]|HGAPP:+|APNID=apnid | +; |\ / | |APNID=ALL | | | |MSUSERS | \ /

Parameters

APN1=apn1 Access Point Name (APN) first partText string 1 ~ 41 characters

APN2=apn2 APN second partText string 1 ~ 41 characters

APNID=apnid APN identifierNumeral 0 ~ 2047 ALL

All APN identifier

MSUSERS All mobile subscribers connected. Subscribers using the entered APN in any of their defined subscriber Packet Data Protocol (PDP) contexts.

Function

This command prints APN data in the Home Location Register (HLR).If parameter MSUSERS is entered, result printout HLR ACCESS POINT NAME DATA is received. Otherwise, answer printout HLR ACCESS POINT NAME DATA is received.If parameter APN1 and, if necessary, APN2 are entered, the APN and the corresponding APN identifier are printed.The entered APN must be compliant with the following syntax:

The length of the APN cannot exceed 62 characters.


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edw://alex?DT=om&TI=HLR+ACCESS+POINT+NAME+DATA&DO=POD&FN=1_19083-CNT2380159Uen.A.html





The APN consists of one of more labels separated by dots. Each label must start with a letter, end with a letter or a digit, and have as criteria characters only letters, digits and hyphen.

APN must not start with the text RAC, LAC or SGSN. APN must not end in .GPRS.

If parameter APNID is entered, the APN identifier and the corresponding APN are printed.If parameter APNID or APN1 and, if necessary, APN2, and MSUSERS are entered, the MSISDN and the IMSI of all the mobile subscriber that use the entered APN in any of their defined subscriber PDP context and the corresponding PDP identifiers are printed. If parameters APNID is equal to ALL, the APN and the corresponding APN identifier for subscribers using a non subscribed APN, are printed.If only parameter MSUSERS is entered, the Mobile Station ISDN Number (MSISDN) and the International Mobile Subscriber Identity (IMSI) of all the mobile subscribers having any subscriber PDP context defined that allows the mobile subscriber to request a non subscribed APN and the corresponding PDP identifier is printed.This command can be initiated from up to 16 Input/Output (IO) devices simultaneously. The order does not remain after system restart.

Example 1

HGAPP:APNID=ALL;All the APNs defined in the HLR and their corresponding APN identifiers are printed.HLR ACCESS POINT NAME DATA(Vary operator to operator) APN APNID AIRTELFUN.COM 7 AIRTELGPRS.COM 6 AIRTELMMS.COM 5 AIRTELWAP.COM 1 BCLDELHI.COM 2 DDD.COM 8 MARTINDEL.COM 10 MARTINLOTTERY.COM 11 PLAYWINDEL.COM 3 PNBINDIA.COM 4 SBIINDIA.COM 12 SUNSHINEDEL.COM 9

Example 2

HGAPP:APNID=5;

The APN corresponding to the APNID 5 is printed.


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HGSDP DUMP

HGSDP command gives the status of the subscriber. It also gives us the list of all the services provided to the subscriber.The HGSDP dump is required by the various departments for checking the status of the subscribers of their intrest.

Home Location Register, Subscriber Data, Print

Command / \ / \ | / \ | |MSISDN=msisdn...| | |ALL | | | | | |SUDA| |HGSDP:+IMSI=imsi... + |,+ + |; | | | |SSDA| | |CONNECTED | | |LOC | | \ / | \ / | \ /

Parameters

ALL All subscriber data

CONNECTED All connected subscribers

IMSI=imsi International Mobile Subscriber Identity (IMSI) See the Application Information for block HTRAN .

LOC Subscriber location data

MSISDN=msisdn Mobile Station International ISDN Number (MSISDN) See the Application Information for block HTRAN .

SSDA Permanent and supplementary service subscriber data

SUDA Permanent subscriber data

Function

This command prints subscriber data for mobile subscribers in HLR.Answer printout HLR SUBSCRIBER DATA is received. Associated answer printouts are also received depending on the parameter given:

PERMANENT SUBSCRIBER DATA , SUPPLEMENTARY SERVICE DATA and LOCATION DATA answer printouts are received when parameter ALL is entered.

PERMANENT SUBSCRIBER DATA is received when parameter SUDA is entered.

PERMANENT SUBSCRIBER DATA and SUPPLEMENTARY SERVICE DATA answer printouts are received when parameter SSDA is entered.

LOCATION DATA answer printout is received when parameter LOC is entered.


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edw://alex?DT=om&TI=LOCATION+DATA&DO=POD&FN=4_19083-CNT2380034Uen.E.html

edw://alex?DT=om&TI=SUPPLEMENTARY+SERVICE+DATA&DO=POD&FN=3_19083-CNT2380034Uen.C.html


edw://alex?DT=om&TI=PERMANENT+SUBSCRIBER+DATA&DO=POD&FN=2_19083-CNT2380034Uen.B.html


edw://alex?DT=om&TI=LOCATION+DATA&DO=POD&FN=4_19083-CNT2380034Uen.E.html




edw://alex?DT=om&TI=HLR+SUBSCRIBER+DATA&DO=POD&FN=1_19083-CNT2380034Uen.D.html

edw://alex?DT=om&CW=HTRAN&DO=AI&FN=2_15518-CNT2380047Uen.T.html

edw://alex?DT=om&CW=HTRAN&DO=AI&FN=2_15518-CNT2380047Uen.T.html


This command can be initiated from up to 16 Input/Output (IO) devices simultaneously. The order does not remain after system restart.

Example 1

HGSDP:CONNECTED;

Subscriber data for all connected subscribers are printed.

Example 2

HGSDP:IMSI=1234567890,ALL;All subscriber data for the mobile subscriber with IMSI 1234567890 are printed

THE SCR SHEET


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The SCR(Successfull Call Rate) Sheet is made on daily basis for finding the Success Call Rate of Punjab,Haryana,Himachal Pardesh and Jammu & Kashmir region.The Punjab region include MSC1,MSC2,MSC3,PBGMSC1,PBGMSC2,MSC6,JALMSC1 and PBGMSC3.The Haryana region include HRYMSC1.The HP region include SHMMSC2 and J&K region includes JKMSC1 and SRIMSC1.Tools used are:1.WINFOIL2.OSS

The snapshot of SCR Sheet is as shown below:

The command used is:

IO FUNCTIONS, FILE TO ALPHANUMERIC DEVICE, TRANSFER

1 Format

1.1 Command

/ \ | / \| | |NF ||IOFAT:FILE=file[,IO=io]|,+ +|; | |HEX|| | \ /| \ /

1.2 Parameters

FILE=file File name. HEX Hexadecimal printout. IO=io IO-device identity. NF No formatting.


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2 Function

This command executes output of a specified file, single or subfile, on a specified alphanumeric device or, if parameter IO=io is omitted, on the device from which the command was given. If the parameter NF is specified, the file is output without editing or specifying block limits. This is suitable only for alphanumerical output files, e.g. log files. If NF is omitted, block limits are included in the output.If NF is omitted and the file is binary, the output will be in edited hexadecimal form.If parameter HEX is given it will be output in edited hexadecimal form independent of file type.Note: When a printout is to be done in HEX-format with parameter HEX, the parameter NF must be omitted!The command does not remain after system restart.

The various parameters used to calculate SCR are

PARAMETERS DESCRIPTION

NCALLSNumber of calls (sufficient information received to discriminate between the different traffic types)

NBANS Number of B-answersNABEFD Number of A-replacements before diallingNADURD Number of A-replacements during diallingNAAFTD Number of A-replacements after dialling

NABEFA1Number of A-replacements before B-answer, within 10 seconds (calls that do not receive end-of-selection information from the remote end and do not reach end-of-selection are counted here)

NABEFA2 Number of A-replacements before B-answer, exceeding 10 secondsNTOBEFD Number of time-outs before diallingNTODURD Number of time-outs during diallingNTOBEFA Number of time-outs before B-answerNBBUSY Number of B-Subscribers busy

NBOUTNumber of B-Numbers out of order, interception marked B-Subscriber, and B-Numbers barred for incoming calls

NBNOEX Number of B-Numbers that do not exist

NCAWNOANumber of calls offered to busy subscribers with call waiting, that are not answered

NNMBLO Number of calls blocked due to network management actions(Successful)

SCR=(NBANS+NABEFD+NADURD+NAAFTD+NABEFA1+NABEFA2+NTOBEFD+NTODURD+NTOBEFA+NBBUSY+NBOUT+NBNOEX+NCAWNOA+NNMBLO)/NCALLS

THE DAILY GSM MAPA

The GSM Technical MAPA(Maintenance And Performance Analysis) is a daily report that shows the daily network performance. In this report a regular data is


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maintained about the different sections of the network. The study of this report helps in keeping an eye on the network’s performance. This report includes data about in roamers, outroamers, installed capacity, subscriber’s data, prepaid data, voicemail, etc.

Various commands are used for getting the data that is to be filled in the report. These commands are given in WINFIOL,the software which is directly connected to the MSCs. Some of the columns require data that has to be taken from other systems.

Below is the shot of the sheet of the report.

Various commands are given in the winfoil for preparing the reports. The description to all the commands can be searched in Alex library.The various parameters are as explained below:

Sr.No. PARAMETER DESCRIPTIONInstalled Capacity(Switching Network Capacity)

1 HLR(K) Capacity of HLR in Kilo


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2 No. of MSC’s Total no. of MSC’s in a state.For eg. The no. of MSC’s for Punjab are eight

3 Total MSC Capacity(Erls) Total traffic that all the MSC’s of a state can handle.

4 Total MSC Capacity(BHCA)[BHCA-Busy Hour Call Attempt]

Maximum capacity of MSC to accept calls in busy hour.

5 IN Prepaid(Equipped BHCA) Maximum number of calls that can be handled by a Service Data Point during busy hour.

Subscriber DataHLR(at 00:00 hrs)

6 Total HLR Total number of subscribers7 Registered Total no. of subscribers which are

registered in the HLR.8 Unregistered Connections cancelled due to factors like

lack of bill paymentVLR(at NBH)

9 Total VLR Sum of all the subscribers of all the MSC’s of the state and inroamers who have location updated in the MSC’s of the state

10 Attached Subscribers who are using MSC’s of the state to route their calls presently.

11 Detached Subscribers who are not using MSC’s of the state.

IN Subs.(Prepaid)12 Installed All subscribers having Prepaid connection13 Active Prepaid subscribers who can make both

incoming and outgoing calls. 14 Disconnections Prepaid subscribers who can not make

both incoming and outgoing calls as their grace period has expired.

15 Recharges Number of subscribers who have recharged.

16 First call to IVR[IVR-Interactive Voice Response]

*123# is the number for checking the balance. This parameter shows how many subscribers have checked their balance. A particular subscriber can make any number of calls to this number but only the first call of the subscriber is counted in this parameter.

17 Grace period Total number of subscribers in the grace period.After grace period the registration of SIM card fails.

18 1-30 days Number of subscribers which are having 1-30 days left for recharging.

19 31-60 days Number of subscribers which are having 31-60 days left for recharging.

20 61-90 days Number of subscribers which are having


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61-90days left for recharging.Roamers(at NBH)

21 In Roamers(Total) Total number of subscribers of any other state or coutry who are location updating in Airtel,Punjab network.

22 In Roamer(National) Subscribers of any other state in India (whether of Airtel or any other operator) who are location updating in Airtel,Punjab network.

23 In Roamer(International) International subscribers who are location updating in Airtel,Punjab network.

24 Out Roamer(Total) Total number of Airtel(Punjab) subscribers who are location updating in the network of any other state or country.

25 Out Roamer(National) Total number of Airtel(Punjab) subscribers who are location updating in the network of any other state in India

26 Out Roamer(International) Total number of Airtel(Punjab) subscribers who are location updating in the network of any other country.

GPRS27 Number of registered GPRS

subscribersNumber of subscribers which can use the facility of GPRS.

Network UsageSwitching Network Usage

28 Network Busy Hour Busy hour of the day i.e. maximum usage at that time.

29 BH Traffic(Erl) Total Traffic in the Busy hour.30 Switch BHCA Calls which have reached till MSC in the

busy hour.VMS Usage[VMS-Voice Mail Service]

Calls going to Voice Mail depending on subscribers choice(Busy, Out of coverage or Out of reach)

31 Voice Mail Boxes Equipped Total number of Voice Mail Boxes equipped.

32 Voice Mail Boxes Assigned Total number of Voice Mail Boxes that are assigned.

The commands used are:

MGSVPMOBILE TELEPHONY, MOBILE SUBSCRIBER SURVEY


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CommandMGSVP;

Parameters

No parameters

Function:The command MGSVP is used to print the HLR address, the number of currently registered mobile subscribers and the number of attached mobile subscribers from each HLR.The total number of registered mobile subscribers and the total number of attached mobile subscribers in the MSC/VLR are printed as well.It is possible to give the command simultaneously from 16 IO devices.hlraddr Home Location Register (HLR) address Expressed as na-ai where: na Nature of address indicator 3National significant number 4International number ai Address information Digit string 1 - 15 decimal digits

nsub Number of registered mobile subscribers in the (MSC/VLR) nsuba Number of attached mobile subscribers in the MSC/VLR for the specified addresstotnsub Total number of registered mobile subscribers in the MSC/VLR

totnsuba Total number of attached mobile subscribers in the

SAAEPSIZE ALTERATION OF DATA FILES, ALTERATION EVENT

Command / \ / / \\ |sae| | |block||SAAEP:SAE=+ + |, BLOCK= + +|; |ALL| | |ALL || \ / \ \ //

Parameters

BLOCK=block Block name Identifier 1 - 7 character


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SAE=sae Size Alteration Event Numeral 0 - 8192

The maximum value is defined in the Operating System area as highest SAE no. Function:

This command is used to print file size information of Size Alteration Events (SAEs) defined in the system.The parameter SAE specifies the Size Alteration Event number. The SAE type can be local or global. The table indicates the number range for local and global SAEs:

Table 1

SAE Type SAE number rangeGLOBAL 0 – 499LOCAL 500 – 899GLOBAL 900 - highest usable SAE number defined in the Operating System

Area

If the SAE number specified in parameter SAE is of type LOCAL, the parameter BLOCK must also be specified. If value ALL is specified for parameter BLOCK then file size information of the specified LOCAL SAE in all participating blocks are printed.If the SAE number specified in parameter SAE is of type GLOBAL, the parameter BLOCK must not be specified.If parameter value ALL is specified for parameter SAE then file size information of all SAEs defined in the system are printed. If a block name is specified together with ALL for parameter SAE, then all SAEs defined in the specified block are printed. The function uses the SAE database tables where all SAEs that are defined in the system are stored. If the SAE database tables are not complete, the function allows file size information of one SAE to be printed.The order does not remain after system restart.

HGLSP

Home Location Register, Mobile Subscriber Location Survey, Print

Command

HGLSP[:GPRS];

Parameters

GPRS General Packet Radio Service (GPRS) network GPRS mobile subscriber location survey will be printed.


98


Function:

This command prints the mobile subscriber location survey for non-GPRS or GPRS network subscribers. Answer printout HLR MOBILE SUBSCRIBER LOCATION SURVEY is received if optional parameter GPRS is not specified. This printout is made for all the Visitor Location Registers (VLR) where mobile subscribers belonging to this Home Location Register (HLR) are registered. The current number of mobile subscribers in each VLR is printed as well. If there are any characteristics defined for these VLRs,then mobile subscribers in unknown location, restricted location and barred location will be printed.

Answer printout HLR GPRS MOBILE SUBSCRIBER LOCATION SURVEY is received if optional parameter GPRS is specified. This printout is made for all the Serving GPRS Support Nodes (SGSN) where mobile subscribers belonging to this HLR are registered. The current number of mobile subscribers in each SGSN is printed as well.

If there are any characteristics defined for these SGSNs, it will be indicated. Furthermore the current number of GPRS network mobile subscribers in unknown location, restricted location and barred location will be printed.

IOFAT

IO FUNCTIONS, FILE TO ALPHANUMERIC DEVICE, TRANSFER

Command / \ | / \| | |NF ||IOFAT:FILE=file[,IO=io]|,+ +|; | |HEX|| | \ /| \ /

Parameters

FILE=file File name. HEX Hexadecimal printout. IO=io IO-device identity. NF No formatting.

Function:

This command executes output of a specified file, single or subfile, on a specified alphanumeric device or, if parameter IO=io is omitted, on the device from which the command was given. If the parameter NF is specified, the file is output without editing or specifying block limits. This is suitable only for alphanumerical output files, e.g. log files. If NF is omitted, block limits are included in the output. If NF is omitted and the file is binary, the output will be


99


in edited hexadecimal form. If parameter HEX is given it will be output in edited hexadecimal form independent of file type. Note: When a printout is to be done in HEX-format with parameter HEX, the parameter NF must be omitted. The command does not remain after system restart.For various types of interaction with the system two softwares are used, namely:1. WINFIOL2. EXCEEDThe screenshots of the two softwares is given.

Figure: Screenshot of WINFOIL


100


Figure: Screenshot of EXCEED SERVER


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. C7 AND PROCESSOR LOAD

The c7 and processor load reports were made on daily basis,for checking various parameters related to the network.Both these reports contains different data ,and data for both of these report is fetched in different ways.The c7 report gives us the information about the average transmiting and receving traffic.it gives us information about all the c7’s of the particular node.The purpose of this report is to monitor and maintain the existing links and to plan for new links.The percentage utilization of links should not be greater than 30%.If the utilization is greater than 30% steps are taken to improve it.

The data for c7 report is taken from metrica server

From the metrica server we download the required report and then change it into required format.wemake the c7 report for following:

PUN/MSC1 PUN/MSC2 PUN/MSC3 PUN/PBGMSC1


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PUN/PBGMSC2 PUN/MSC6 PUN/JALMSC PUN/PBGMSC3 PUN/PBSCP1 PUN/PBSCP2 PUN/PBSCP3 PUN/JKMSC1 PUN/SRIMSC1 PUN/MSCHRY PUN/SHMMSC2

The figure shows the snapshot of the c7 report

The processor load report gives us the peak processor load of the mscs.

Also the links are confirmed by giving following command in winfiol:

c7ltp:ls=all;

This command gives us the total number of links &SPID(Signalling Point Identity).


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With the completion of this training I am now aware of the technical setup of the

GSM network. I have worked for six complete months in the Performance

Department. I have worked almost as an employee engineer to the extent of my

technical capabilities. Doing all these I have acquired a lot of knowledge about

the working of my Department (Network Switching and Subsystem).

I was the part of one of the most happening and demanding field of

communication i.e. the Global System for Mobile and spending six months into it

really proved very useful to me and I have gained following things out of it:

I got an overview of the actual working of GSM network

I worked practically which helped me in being more familiar to the

practical tasks which I am supposed to do in the long run.

I learned inter department coordination and the qualities such as

team work.

Training helped me increasing my working skills & stamina and also

showed me the atmosphere which we have to join after completion of

the degree program.

Finally the main advantage of this training was that I have now opened doors for my easy entry to the giant mobile telecom industry.


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I have concluded following things out of the training:

The GSM system is very vast field and six months are nothing to

understand all of its elements even briefly.

Some introduction to the GSM prior to the training in this field is

very essential to make the understandings easy at initial phase.

The communication hardware studied theoretically prior to the

training was physically very small part of the transmission

system.

Inter department coordination and team works are the key factors

for development of an enterprise.

ractical tasks and projects should be taken seriously during the

degree program as one should be practically sound to be

successful in the modern industry.


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www.airtelindia.com

www.ericsson.com

Active library explorer (ALEX)

Ericsson system manuals

www.airtelworld.com

Daily Dairy by Nandita


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http://WWW.airtelworld.com/

http://WWW.ericsson.com/

http://WWW.airtelindia.com/

Project Report

Documents

training period

nandita nandita ece

gurcharan singh training

nss mr

gsm technology

gsm architecture

nss components

gsm transmission process