INDUSTRIAL TRAINING REPORT

ON

GSM TECHNOLOGY

AT

BSNL

BACHELOR OF ENGINEERING

IN

INFORMATION TECHNOLOGY

SUBMITTED BY SUBMITTED TO

VII SEM IV YEAR

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DECLARATION

I student of BE (VII) semester, hereby declare that the industrial training report on “GSM TECHNOLOGY “ submitted to Department in partial fulfilment of degree of BE is the original work conducted by me .

The information and data given in the report is authentic to the best of my knowledge.

- - - - - - - - - - - - - - - - - - -- (Signature)

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CONTENTS

S. NO. TOPIC PAGE NO.

1. Company Profile About Company Service provided by BSNL

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2. Introduction & Basic concept Definition Evolution of Mobile

Telephone system GSM GSM Network The switching system The operator & support system GSM Network Area GSM Specification

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9910-1112-1314-17

3. GSM Architecture 18-22

4. Other GSM Entities GSM Interface Signal processing in GSM Frame Structure of GSM Channels Used in GSM GSM Subscriber Services Supplementary Services

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25-265. Conclusion 27

6. Bibliography 28

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COMPANY PROFILE

About company

Bharat Sanchar Nigam Limited (abbreviated BSNL) is an Indian stateowned telecommunications company headquartered in New Delhi, India. It was incorporated on 15 September 2000. It took over the business of providing of telecom services and network management from the erstwhile Central Government Departments of Telecom Services (DTS) and Telecom Operations (DTO), with effect from 1 October 2000 on going concern basis. It is the largest provider of fixed telephony and fourth largest mobile telephonyprovider in India, and is also a provider of broadband services. However, in recent years the company's revenue and market share plunged into heavy losses due to intense competition in the Indian telecommunications sector.[2][3] BSNL is India's oldest and largest communication service provider (CSP). It had a customer base of 117 million as of Jan 2014.[4] It has footprints throughout India except for the metropolitan cities of Mumbai and New Delhi, which are managed by Mahanagar Telephone Nigam (MTNL).

Services Provided By BSNL

BSNL provides almost every telecom service in India. Following are the main telecom services provided by BSNL:

Optical Infrastructure and DWDM : BSNL owns the biggest OFC network in India. Also the DWDM network is one of the biggest in the world. The DWDM equipments purchased in open tender at BSNL are mainly of United Telecoms Limited ( UTL) ) make, which was declared lowest cost in competitive bidding. Rest DWDM equipments are from Huawei. The SDH equipments are mainly from Tejas Networks, Huawei, ZTE, ECI, UT STAR etc.

Market Share : As of 30 November 2013, BSNL had 12.9% marketshare in India and stands as 5th Telecom Operator in India and 67% market share in ADSL Services.

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Managed Network Services : BSNL is providing complete Telecom Services Solution to the Enterprise Customers i.e. MPLS Connectivity, Point to Point Leased Lines and Internet Leased Lines .

Universal Telecom Services : Fixed wireline services and landline in local loop (WLL) using CDMA Technology called bfone andTarang respectively. As of 30 June 2010, BSNL had 75% marketshare of fixed lines.

Cellular Mobile Telephone Services: BSNL is major provider of Cellular Mobile Telephone services using GSM platform under the brand name Cellone & Excel (BSNL Mobile). As of 30 June 2010 BSNL has 13.50% share of mobile telephony in the country. It has 95.54 million customers using BSNL mobile.

WLL-CDMA Telephone Services: BSNL's WLL (Wireless in Local Loop) service is a service giving both fixed line telephony & Mobile telephony.

Internet: BSNL provides Internet access services through dial-up connection (as Sancharnet through 2009) as Prepaid, NetOne as Postpaid and ADSL broadband as BSNL Broadband BSNL held 55.76% of the market share with reported subscriber base of 9.19 million Internet subscribers with 7.79% of growth at the end of March 2010 Top 12 Dial-up Service providers, based on the subscriber base, It Also Provides Online Games via its Games on Demand (GOD)

Intelligent Network (IN): BSNL offers value-added services, such as FreePhone[9] Service (FPH), India Telephone Card (Prepaid card), Account Card Calling (ACC), Virtual Private Network (VPN), Tele-voting, Premium Rae Service (PRM), Universal Access Number (UAN).

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3G:BSNL offers the '3G' or the'3rd Generation' services which includes facilities like video calling, mobile broadband, live TV, 3G Video portal, streaming services like online full length movies and video on demand etc.

IPTV:BSNL also offers the 'Internet Protocol Television' facility which enables customers to watch television through internet.

FTTH: Fibre To The Home facility that offers a higher bandwidth for data transfer. This idea was proposed on post-December 2009 GSM Technology

Helpdesk: BSNL's Helpdesk (Helpdesk) provide help desk support to heir customers for their services.

VVoIP: BSNL, along with Sai Infosystem - an Information and Communication Technologies (ICTs) provider - has launched Voice and Video Over Internet Protocol (VVoIP). This will allow to make audio as well as video calls to any landline, mobile, or IP phone anywhere in the world, provided that the requisite video phone equipment is available at both ends.

WiMax: BSNL has introduced India's first 4th Generation High-Speed Wireless Broadband Access Technology with the minimum speed of 256kbit/s. The focus of this service is mainly rural customer where the wired broadband facility is not available.

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INTRODUCTION AND BASIC CONCEPTS

Definition

Global system for mobile communication (GSM) is a globally accepted standard for digitalcellular communication. GSM is the name of a standardization group established in 1982 tocreate a common European mobile telephone standard that would formulate specifications for apan-European mobile cellular radio system operating at 900 MHz. It is estimated that manycountries outside of Europe will join the GSM partnership.

The Evolution of Mobile Telephone Systems

Cellular is one of the fastest growing and most demanding telecommunications applications. Today, it represents a continuously increasing percentage of all new telephone subscriptions around the world. Currently there are more than 45 million cellular subscribers worldwide, and nearly 50 percent of those subscribers are located in the United States. It is forecasted that cellular systems using a digital technology will become the universal method of telecommunications. By the year 2015, forecasters predict that there will be more than 200 million cellular subscribers worldwide. It has even been estimated that some countries may have more mobile phones than fixed phones by the year 2000 (see Figure 1).

Figure 1.

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Cellular Subscriber Growth Worldwide

The concept of cellular service is the use of low-power transmitters where frequencies can be reused within a geographic area. The idea of cell-based mobile radio service was formulated in the United States at Bell Labs in the early 1970s. However, the Nordic countries were the first to GSM Technology Page 10 introduce cellular services for commercial use with the introduction of the Nordic Mobile Telephone (NMT) in 1981. Cellular systems began in the United States with the release of the advanced mobile phone service (AMPS) system in 1983. The AMPS standard was adopted by Asia, Latin America, and Oceanic countries, creating the largest potential market in the world for cellular. In the early 1980s, most mobile telephone systems were analog rather than digital, like today's newer systems. One challenge facing analog systems was the inability to handle the growing capacity needs in a cost-efficient manner. As a result, digital technology was welcomed. The advantages of digital systems over analog systems include ease of signaling, lower levels of interference, integration of transmission and switching, and increased ability to meet capacity demands.

GSM

Throughout the evolution of cellular telecommunications, various systems have been developed without the benefit of standardized specifications. This presented many problems directly related to compatibility, especially with the development of digital radio technology. The GSM standard is intended to address these problems. From 1982 to 1985 discussions were held to decide between building an analog or digital system. After multiple field tests, a digital system was adopted for GSM. The next task was to decide between a narrow or

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broadband solution. In May 1987, the narrowband time division multiple access (TDMA) solution was chosen.

The GSM Network

GSM provides recommendations, not requirements. The GSM specifications define the functions and interface requirements in detail but do not address the hardware. The reason for this is to limit the designers as little as possible but still to make it possible for the operators to buy equipment from different suppliers. The GSM network is divided into three major systems: the switching system (SS), the base station system (BSS), and the operation and support system (OSS). The basic GSM network elements are shown in Figure 2

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GSM Network Elements

The Switching System

The switching system (SS) is responsible for performing call processing and subscriber-related functions. The switching system includes the following functional units:

Home location register (HLR) — The HLR is a database used for storage and management of subscriptions. The HLR is considered the most important database, as it stores permanent data about subscribers, including a subscriber's

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service profile, location information, and activity status. When an individual buys a subscription from one of the PCS operators, he or she is registered in the HLR of that operator. GSM Technology

Mobile services switching center (MSC )—The MSC performs the telephony switching functions of the system. It controls calls to and from other telephone and data systems. It also performs such functions as toll ticketing, network interfacing, common channel signaling, and others.

Visitor location register (VLR)—The VLR is a database that contains temporary information about subscribers that is needed by the MSC in order to service visiting subscribers. The VLR is always integrated with the MSC. When a mobile station roams into a new MSC area, the VLR connected to that MSC will request data about the mobile station from the HLR. Later, if the mobile station makes a call, the VLR will have the information needed for call setup without having to interrogate the HLR each time.

Authentication center (AUC)—A unit called the 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.

Equipment identity register (EIR )—The EIR is a database that contains information about the identity of mobile equipment that prevents calls from stolen, unauthorized, or defective mobile stations. The AUC and EIR are implemented as stand-alone nodes or as a combined AUC/EIR node.

The Base Station System (BSS)

All radio-related functions are performed in the BSS, which consists of base station controllers (BSCs) and the base transceiver stations (BTSs).

BSC —The BSC provides all the control functions and physical links between the MSC and BTS. It is a high-capacity switch that provides functions such as handover, cell configuration data, and control of radio frequency (RF) power

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levels in base transceiver stations. A number of BSCs are served by an MSC. GSM Technology

BTS —The BTS handles the radio interface to the mobile station. The BTS is the radio equipment (transceivers and antennas) needed to service each cell in the network. A group of BTSs are controlled by a BSC.

The Operation and Support System

The operations and maintenance center (OMC) is connected to all equipment in the switching system and to the BSC. The implementation of OMC is called the operation and support system (OSS). The OSS is the functional entity from which the network operator monitors and controls the system. The purpose of OSS is to offer the customer cost-effective support for centralized, regional, and local operational and maintenance activities that are required for a GSM network. An important function of OSS is to provide a network overview and support the maintenance activities of different operation and maintenance organizations.

Additional Functional Elements

Other functional elements shown in Figure 2 are as follows:

Message center (MXE)— The MXE is a node that provides integrated voice, fax, and data messaging. Specifically, the MXE handles short message service, cell broadcast, voice mail, fax mail, email, and notification.

Mobile service node (MSN)— The MSN is the node that handles the mobile intelligent network (IN) services.

Gateway mobile services switching center (GMSC)— A gateway is a node used to interconnect two networks. The gateway is often implemented in an MSC. The MSC is then referred to as the GMSC. GSM Technology .

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GSM interworking unit (GIWU)— The GIWU consists of both hardware and software that provides an interface to various networks for data communications. Through the GIWU, users can alternate between speech and data during the same call. The GIWU hardware equipment is physically located at the MSC/VLR. GSM Network Areas The GSM network is made up of geographic areas. As shown in Figure 3, these areas include cells, location areas (LAs), MSC/VLR service areas, and public land mobile network (PLMN) areas. Figure 3. Network Areas The cell is the area given radio coverage by one base transceiver station. The GSM network identifies each cell via the cell global identity (CGI) number assigned to each cell. The location area is a group of cells. It is the area in which the subscriber is paged. Each LA is served by one or more base station controllers, yet only by a single MSC (see Figure 4). Each LA is assigned a location area identity (LAI) number.

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GSM Network Areas

The GSM network is made up of geographic areas. As shown in Figure 3, these areas include cells, location areas (LAs), MSC/VLR service areas, and public land mobile network (PLMN) areas.

Figure 3. Network Areas

The cell is the area given radio coverage by one base transceiver station. The GSM network

identifies each cell via the cell global identity (CGI) number assigned to each cell. The location

area is a group of cells. It is the area in which the subscriber is paged. Each LA is served by one

or more base station controllers, yet only by a single MSC (see Figure 4). Each LA is assigned a

location area identity (LAI) number.

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An MSC/VLR service area represents the part of the GSM network that is covered by one MSC

and which is reachable, as it is registered in the VLR of the MSC (see Figure 5).

Figure 4. Location Areas

Figure 5. MSC/VLR Service Areas

The PLMN service area is an area served by one network operator

(see Figure 6).

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Figure 6. PLMN Network Areas

GSM Specifications

Before looking at the GSM specifications, it is important to understand the following basic terms:

Bandwidth —the range of a channel's limits; the broader the bandwidth, the faster data can be sent

Bits per second (bps)— a single on-off pulse of data; eight bits are equivalent to one byte

Frequency —the number of cycles per unit of time; frequency is measured in hertz (Hz)

Kilo (k)— kilo is the designation for 1,000; the abbreviation kbps represents 1,000 bits per second

Megahertz (MHz)— 1,000,000 hertz (cycles per second)

Milliseconds (ms)— one-thousandth of a second

Watt (W)— a measure of power of a transmitter

Specifications for different personal communication services (PCS) systems vary among the different PCS networks. Listed below is a description of the specifications and characteristics for GSM.

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Frequency band —The frequency range specified for GSM is 1,850 to 1,990 MHz (mobile station to base station).

Duplex distance —The duplex distance is 80 MHz. Duplex distance is the distance between the uplink and downlink frequencies. A channel has two frequencies, 80 MHz apart.

Channel separation —The separation between adjacent carrier frequencies. In GSM, this is 200 kHz.

Modulation —Modulation is the process of sending a signal by changing the characteristics of a carrier frequency. This is done in GSM via Gaussian minimum shift keying (GMSK).

Transmission rate —GSM is a digital system with an over-the-air bit rate of 270 kbps.

Access method —GSM utilizes the time division multiple access (TDMA) concept. TDMA is a technique in which several different calls may share the same carrier. Each call is assigned a particular time slot.

Speech coder —GSM uses linear predictive coding (LPC). The purpose of LPC is to reduce the bit rate. The LPC provides parameters for a filter that mimics the vocal tract. The signal passes through this filter, leaving behind a residual signal. Speech is encoded at 13 kbps.

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GSM ARCHITECTURE

GSM Architecture

Global System for Mobile (GSM) is a second generation cellular system standard that was developed to solve the fragmentation problems of the first cellular systems in Europe. GSM was the world’s first cellular system to specify digital modulation and network level architectures andservices, and is the world’s most popular 2G technology. Before GSM, European countries used different cellular standards throughout the continent, and it was originally developed to serve as the pan-European cellular service and promised a wide range of network services through the use of ISDN. GSM’s success has exceeded the expectations of virtually everyone, and it is now the world’s most popular standard for new cellular radio and personal communications equipmentthroughout the world. The task of specifying a common mobile communication system for Europe in the 900 MHz band was taken up in the mid – 1980s by the GSM (Groupe special mobile) committee.

Figure 7- GSM Architecture

GSM Architecture is divided into three main parts:

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1. Mobile Station (MS)2. Base Station System (BSS)3. Network and Switching Subsystem (NSS)

In this architecture, a MS communicates with a BSS through the radio interface. The BSS is connected to the NSS by communicating with a mobile switching center (MSC).

Mobile Station

The MS consists of two parts: the subscriber identity module (SIM) and the mobile equipment (ME). Sometime it also contains a third part called terminal equipment (TE), which can be a PDA or PC connected to the ME. In this case, the first two parts (i.e., ME and SIM) are calledthe mobile terminal (MT).

Characteristic of Subscriber Identity Module (SIM)

A SIM can be a smart card that size is usually the size of a credit card. A SIM can be a smaller-sized “plug-in SIM”.

The SIM is protected by a personal identity number (PIN) between four to eight digits in length. The PIN is initially loaded by the network operator at the subscription time. This PIN can be deactivated or changed by the user.

At the time of switch ON the MS, the user is asked to enter the PIN. If user enters the wrong PIN upto three consecutive attempts, the SIM will be blocked and the MS cannot be used. To unblock the SIM, the user is asked to enter the eight PIN unblocking key(PUK).

A SIM contains the subscriber-related information, including the PIN and PUK codes.

The subscriber-related data also include a list of abbreviated and customized short dialing numbers, short messages received.

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Parts of the SIM information can be modified by the subscriber either by using the keypad of an MS or a personal computer using an RS232 connections data retrieved by using software on a PC.

The SIM card can be updated over the air through SIM toolkit, with which network operators can remotely upgrade an MS by sending codes through short messages.

These messages are issued from a SimCard server and are received by MSs equipped with SIM-toolkit capability.

SIM Toolkit provides security-related functions so that SIM cards are not falsely modified.

Characteristic of Mobile Equipment (ME)

The ME contains the noncustomer-related hardware and software specific to the radio interface.

When the SIM is removed from an MS, the ME cannot be used for reaching the service, except for emergency calls.

At every new connection between MS (SIM) and the network, the characteristic indication of the ME, called classmark, is given to the network.

This SIM-ME design supports portability, as well as enhancing security. Usually, the ME is the property of the subscriber. The SIM, although loaned to the subscriber, is the property of the service provider.

Base Station System

The BSS consists of two parts:

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A) Base Transceiver Station (BTS)B) Base Station Controller(BSC)

The BTS contains transmitter, receiver, signaling equipment specific to the radio interface in order to contact the MSs. An important part of the BTS is the transcoder/rate adapter unit (TRAU) that carries out GSM-specific speech encoding/decoding and rate adaption in data transmission.

Functions of BSC

The BSC is responsible for the switching functions in the BSS, and is in turn connected to an MSC in the NSS.

The BSC supports radio channel allocation/release and handoff management.

A BSC may connect to several BTSs and maintain cell configuration data of these BTSs.

The BSC communicates with the BTSs using ISDN protocols via the A-bis interface.

Network and Switching Subsystem (NSS)

The NSS supports the switching functions, subscriber profiles, and mobility management. The basic switching function in the NSS is performed by the MSC.

This interface follows a signaling protocol used in the telephone network The MSC also communicates with other network elements external to GSM utilizing the same signaling protocol.

The current location of an MS is usually maintained by HLR and VLR. When an MS move from the home system to a visited system, its location is registered at the VLR of the visited system. The VLR then informs the MS’s HLR of its current location.

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The authentication center (AuC) is used in the security data management for the authentication of subscribers. The AuC may be connected with the HLR.

An incoming call is routed to an MSC, unless the fixed network is able to interrogate the HLR directly. That MSC is called the gateway MSC (GMSC).

The GMSC obtains the location information routes the calls to the visited MSC of the subscribers to receive the calls.

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OTHER GSM ENTITIES

GSM Interfaces

GSM interfaces are used for connection of various nodes in GSM network. There are differentGSM interfaces.

Um Interface:

It is also known as Air Interface or Radio interface. It is the most important part in any mobile radio system and interfaces MS and BTS.

It supports maximum spectral efficiency and universal use of any compatible mobile station in a GSM network.

The radio interface uses the Link Access Protocol on D channel (LAPD).

Abis Interface:

Abis interfaces are vendor specific. It interfaces BSC and BTS. The interface comprises traffic and control channels. Functions implemented at Abis interface are:

Traffic channel transmission, terrestrial and radio channel management.

Voice-data traffic exchange.

Signaling exchange between BSC and BTS.

Transporting synchronization information from BSC to BTS.

This interface supports two types of communication links:

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Traffic channels at 64 kbps. Signaling channels at 16 kbps

The two messages handheld by traffic management procedure part of the signaling interface are transparent and non-transparent. Messages between MS and BSC-MSC are transparent messages and they do not require analysis by BTS. But, BTS analysis is required by non-transparentmessages.

A-interface

It is the interface between BSC and MSC. The physical layer of A-interface is a 2Mbps standard CCITT digital connection.

Proprietary M-Interface

It is the interface between physical BSC and the TRAU. TRAU is included in BSC in the GSM network implementation of lucent technologies. The TRAU adapts transmission bit rate of A-interface (64 kbps) to A-bis interface (16 kbps).

Interface between other GSM Entities

MAP (Media Application Protocol) is used to transfer information between GSM PLMN entities. Mobile application and several Application Service Elements (ASEs) are contained in MAP

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Supplementary 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.

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 immediatecharging 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 circuitswitched connection.

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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 restrictionoverrides the presentation.

Closed user groups (CUGs)—CUGs are generally comparable to a PBX. They are agroup of subscribers who are capable of only calling themselves and certain numbers.

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CONCLUSION

In analog communication systems the quality of voice and the speed of communication were not good. Thus an evolution of analog communication systems was needed; Hence GSM Technology was made which improved the communication process by addressing the problems of the previous systems.

It increases the capacity, reduces RF transmission power, and provides international roaming capability, better security against fraud through terminal validation and user authentication. Italso provides encryption capability for information security and privacy, At the same time it is compatible with the ISDN network.

The training at BSNL covered GSM Technology as a whole with key focus on its architectural elements, cell types, interfaces, handover etc.

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Bibliography

The following are the sources that I used while making the project report.

Books- Marie-Bernadette Paulket and Michel Mouly, ”The GSM System

for Mobile Communication”, Ed. 2003, McGraw Hill Publication.

Mobile Communications by Jochen Schiller 2nd Edition, Pearson Education .

WEB-

Wikipedia Tutorialspoint.com

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