SUBMITTED TO: SUBMITTED BY:

ACKNOWLEDGEMENT

Our gratitude, first of all goes to Raj Kumar Goel Institute of Technology for Women, for providing us with a chance to undergo a 6-weeks of industrial training at MTNL (Mahanagar Telephone Nigam Limited), Delhi, one of India’s most prestigious and respected telecommunications company.

We are extremely thankful to JTO and SDE for their valuable guidance and support without which, the completion of this work would have been impossible. Their profound knowledge and sound advice helped us complete this project report to the best of our abilities.

Date: ________

Historical Development of MTNL

1986 Creation of Mahanagar Telephones Nigam Limited

1986 First digital exchange world technology brought to India

1987 Largely Scale introduction of push button telephone made dialing easier.

1988 Phone Plus services multiplied benefits to telephone users.

1992 Voice Mail Service Introduced

1996 ISDN services introduced

1997 Wireless in Local loop introduced

1999 Internet services introduced.

2000 Millennium Telecom Limited, a wholly owned subsidiary of MTNL is born

2001 Launched GSM Cellular Mobile service under the brand name DolphinLaunched WLL Mobile services under the brand name Garuda.The company listed at New York stock exchange(NYSE)United telecom ltd.,MTNL Joint venture in Nepal, for providing WLL based services in Nepal became operational.CLI based Internet express services introduced.

2002 Launched pre-paid GSM Mobile services under the brand name Trump. Email on PSTN lines introduced under the brand name mtnlmail.

2003 Introduced CDMA 1x 2000 Technology under the brand name Garuda 1-x.Introduced pilot project of ADSL based Broadband services. Introduced Virtual Phone services. Mahanagar Telephone Mauritius Ltd. bagged second operator license in Mauritius.

2004 Expanded GSM & CDMA capacity by 800,000 lines each (total 1.6 million lines expanded) STD/ISD rates slashed by almost 60%. MTNL subsidiary MTML obtained license to provide fixed, mobile & ILD services in Mauritius. Launched Wi-Fi & digital certification services. State of the art training centre “CETTM” commissioned.

2005 Leading market in GSM customer additions. Launched broadband services under the brand name “TRI BAND”. Floated tender for 1 million 3G GSM lines.

NETWORK STRUCTURE:

19 Years of Growth

\MTNL as a company, over last nineteen years, grew rapidly by modernizing the network, incorporating the State-of-the-art technologies and a customer friendly approach.

NETWORK INFRASTRUCTURE:

  1986 2006

1.No of exchanges 114 529

2.Equipped capacity (Million) 0.88 8.44

3.Subscriber base (Million) 0.75 5.92

i) Basic Wire line & CDMA Fixed 0.75 3.88

ii) CDMA-Mobile - 0.10

iii) GSM Cellular - 1.94

4.Internet - 1,188,204

5.Broadband - 211,935

6.Public Call Offices (Local and Long Distance)

10,593 279,041

7.No of stations on Long Distance Network 264 39,303

8.No of countries connected overseas on ISD

11 239

9.Digitalization of exchange network Nil 100%

INTRODUCTION:

The Wireless Evolution is achieved through the GSM family of wirelesstechnology platforms - today's GSM, GPRS, EDGE & 3GSM.

It is the basis of a powerful family of platforms for the future - providing a direct link into next generation solutions including GPRS (General Packet Radio Services) EDGE (Enhanced Data for GSM Evolution) and 3GSM.

GSM's unrivalled success can be attributed to many factors, including the unparalleled co-operation and support between all those supplying, running and exploiting the platform. It is based upon a true end-to-end solution, from infrastructure and services to handsets and billing systems.

GSM is a standard that embraces all areas of technology, resulting in global, seamless wireless services for all its customers. It's all part of the Wireless Evolution.

The first cellular mobile system came into existence during the period 1979-1980. This included AMPS (Advance Mobile Phone Service), NMT (Nordic Mobile Telephony), and TACS (Total Access Communication System). These services were analog in nature and hence these were known as First Generation Systems.

During 1990 many digital mobile standards were introduced. These included DAMPS (Digital Advance Mobile Phone Service), GSM (Global System for Mobile Communications), CDMA (Code Division Multiple Access). These are known as Second Generation Systems.

For the introduction of data transfer capability on the Mobile, additional Hardware was introduced in GSM systems, known as GPRS (General Packet Radio Service). These are being referred as 2.5 G Systems.

YEAR EVENT TOOK PLACE

1982 CEPT establishes a GSM group in order to develop the standards for a pan-European cellular mobile system

CEPT adopts WARC 79 recommendation allocating 890-915 MHz and 935-960 MHz for land mobile

GSM created to set standard

1985 Adoption of a list of recommendations to be generated by the group

1987 Digital Technology standards set for TDMA, speech coding, channel: and modulation method.

Telecommunication carriers from 14 European countries sign Memorandum of Understanding (MOU) and agree to install system in 1991

1988 Industrial development started

1989 Acceptance of GSM-1800 system, with GSM as standard

1991 First system deployed (July)

1992 First GSM terminals receive interim type approval

1993 First GSM-1800 network launched

1995 First GSM-1900 network in US & Canada

GENERATION OF GSM

1st generation:- Analog mobile technologies :- AMPS , TACS & NMT. 2nd generation:- digital mobile technologies :- GSM , CDMA

2.5generation:- Enhancement of GSM:- GPRS 3rd generation:- Technologies coursed by ITU-IMT

The following table lists the key events in the GSM evolutionAMPS= Advanced Mobile Phone SystemTACS = Total Access Communication System.NMT=Nordic Mobile Telephones

GPRS-Wireless Data Services.

EDGE—Provides 3 times the data capacity of GPRS.

3G---Uses WCDMA technologies Over Air interface (5MHz).

GSM STANDARDS

GSM-900 StandardThe GSM-900 standard is a standard for digital voice transmission in the 900 MHz band. This so called “primary band" includes two sub bands of 25 MHz

GSM-1800 StandardIn GSM-1800, 1800 MHz band was allocated for digital mobile telephone services which have frequency of 75 MHz this was three times the bandwidth allocated for GSM-900.

GSM-1900 StandardGSM-1900 is the standard for the 1900MHz band. It includes the same network component as the GSM-900 or GSM-1800. The band width of this standard is 60 MHz

GSM Channels/CarriersThe following table will show the channels and carriers of different GSM models.

P-GSM(Primary-GSM)

900

E-GSM

900(Extended-GSM)

R-GSM

900(Railways-GSM)

GSM 1800

GSM 1900

Uplink frequency

890-915 MHz 880-915 MHz 886-915 MHz 1710-1785 MHz

1850-1910 MHz

Down link frequency

935-960 MHz 925-960 MHz 931-960 MHz 1805-1855

1930-1990

MHz MHz

Channel spacing

200 kHz 200 kHz 200 kHz 200 kHz

200 kHz

Carrier Frequency

124 174 144 374 299

Duplex spacing

45 MHZ 45 MHZ 45 MHZ 95 MHZ

80 MHZ

SERVICES:

The ETSI Standards define the telecommunication services. With D900/D1800 the GSM telecommunication services offered to the GSM subscriber are subdivided as follows:

Bearer services (for data only) Tele-services (for voice and data) Supplementary services

Bearer services and tele-services are also called basic telecommunication services. The use of GSM telecommunication services is subject to subscription. A basic subscription permits participation in those GSM telecommunication services that are generally available. If a GSM subscriber roams out of the entitled area there is no possibility of establishing communication (roaming not allowed), except the use of the tele-service emergency call.

Bearer Services

Bearer services are telecommunication services providing the capability of transmission of signals between access points. The bearer services describe what the network can offer (e.g. speech, data and fax).The bearer services are pure transport services for data. Some of the transmission modes and rates already used in modern data networks are implemented; others are planned. The following, already implemented, bearer services provide unrestricted information transfer between the reference points in the mobile stations.

Data CDA (circuit duplex asynchronous) + basic PAD (packet assemblerDisassemble) access

Data CDS (circuit duplex synchronous) PAD CDA (dedicated PAD access) Alternate speech/data CDA (circuit duplex asynchronous) Speech followed by data CDA (circuit duplex asynchronous) Data compression on the GSM radio interface

Teleservices

Teleservices are telecommunication services including terminal equipment functions, which Provide communication between users according to protocols established by agreement between network operators. The teleservices are user end-to-end services (e.g. emergency call and short message service).

Tele-services use both low layer and high layer functions for the control of communication from terminal to terminal. The following tele-services have already been realized:

Telephony Emergency call Short message service (SMS) Short message cell broadcast Automatic facsimile (group 3) Alternative speech and facsimile (group 3)

Supplementary Services

Supplementary Services modify or supplement a basic telecommunication service. Consequently, they cannot be offered to a customer as a stand-alone service. They must be offered together or in association with a basic telecommunication service. The same supplementary service may be applicable to a number of telecommunication services. Most supplementary services are directly inherited from a fixed network, with minor modifications (when needed) to adapt to mobility. Examples of supplementary services are calling line identification and call waiting.

Supplementary services extend beyond the normal bearer services and teleservices (basic telecommunication services) and can be subscribed to separately. In the following a supplementary service is called simply service, in contrast to basic telecommunication service.

Number Identification Services Calling line identification presentation (CLIP) Calling line identification restriction (CLIR)

Call Offering Services Call forwarding unconditional (CFU) Call forwarding on mobile subscriber busy (CFB) Call forwarding on no reply (CFNRy) Call forwarding on mobile subscriber not reachable (CFNRc)

Call Completion Services Call hold Call waiting (CW)

Multi-Party Service Charging Services

Advice of charge (AOC) Call Restriction Services

Barring of all outgoing calls (BAOC) Barring of all outgoing international calls (BOIC) Barring of all outgoing international calls except to home PLMN

country (BOICexHC) Barring of all incoming calls (BAIC) Barring of all incoming calls when roaming outside home PLMN

country (BIC Roam) Closed User Group (CUG)

SPECIFICATIONS:

Trunked Radio system. Access Method - TDMA/FDMA Frequency Bands

Uplink Frequency - 890-915 MHz

Downlink frequency - 935-960 MHz

Bandwidth of GSM system - 25 MHz Channel Bandwidth - 200 KHz Number of Channels - 124 channel pairs (25 MHz/200 KHz) Modulation Method - GMSK(Gaussian Minimum Shift Keying)

BS : Base Station

MS : Mobile Station

Type of access Technology

FDMA (Frequency division Multiple Accesses):- In FDMA, signals from various users are assigned different frequencies. Frequency guard bands are maintained between adjacent signal spectra to minimize crosstalk between channels.

TDMA (TIME DIVISION MULTIPLE ACCESS):- In a TDMA system, data from each user is conveyed in time intervals called “Time slots”. Several slots make up a frame. Each slot is made up of a preamble plus information bits addressed to various stations .the functions of the preamble are to provide identification and incidental information and to allow synchronization of the slot at the intended receiver .Guard times are used between each user’s transmission to minimize crosstalk between channels.

Typical TDMA/ FDMA frame structure

GSM NETWORK STRUCTURE:

Every telephone network needs a well-designed structure in order to route incoming called to the correct exchange and finally to the called subscriber. In a mobile network, this structure is of great importance because of the mobility of all its subscribers [1-4]. In the GSM system, the network is divided into the following partitioned areas.

GSM service area; PLMN service area; MSC service area; Location area; Cells.

GSM Architecture

The basic block diagram of GSM includes Mobile Station (MS), Base Station System (BSS), that includes Base Transceiver System (BTS) and Base Station Controller (BSC), and Switching Subsystem that includes Mobile Switching Centre (MSC) and Gateway MSC (GMSC).

MOBILE STATION (MS)

The MS includes radio equipment and the man machine interface (MMI) that a subscribe needs in order to access the services provided by the GSM PLMN (Public Land Mobile Network). MS can be installed in vehicles or can be portable or handheld stations. The MS may include provisions for data communication as well as voice. A mobile transmits and receives messages to and from the GSM system over the air interface to establish and continue connections through the system.

Functions of MS The primary functions of MS are to transmit and receive voice and data over the air interface of the GSM system. MS performs the signal processing functions of digitizing, encoding, error protecting, encrypting, and modulating the transmitted signals. It also performs the inverse functions on the received signals from the BS.

Power Levels These are five different categories of mobile telephone units specified by the European GSM system: 20 W, 8 W, 5 W, 2 W, and 0.8 W. These correspond to 43 dBm, 39 dBm, 37 dBm, 33 dBm, and 29 dBm power levels. The 20 W and 8 W units (peak power) are either for vehicle-mounted or portable station use.

Subscriber Identity Module (SIM) Card GSM subscribers are provided with a SIM card with its unique identification at the very beginning of the service. By divorcing the subscriber ID from the equipment ID, the subscriber may never own the GSM mobile equipment set. The subscriber is identified in the system when he inserts the SIM card in the mobile equipment. This provides an enormous amount of flexibility to the subscribers since they can now use any GSM-specified mobile equipment. Thus with a SIM card the idea of

“Personalize” the equipment currently in use and the respective information used by the network (location information) needs to be updated. The smart card SIM is portable between Mobile Equipment (ME) units. The user only needs to take his smart card on a trip. He can then rent a ME unit at the destination, even in another country, and insert his own SIM. Any calls he makes will be charged to his home GSM account. Also, the GSM system will be able to reach him at the ME unit he is currently using.

MSISDN : - The real telephone number of a mobile station is the mobile subscriber ISDN number (MSISDN). It is assigned to the subscriber (his or her SIM, respectively), such that a mobile station set can have several MSISDNs depending on the SIM. - CC+NDC+SN - 12digits

IMSI - Each registered user is uniquely identified by its international mobile subscriber identity (IMSI). It is stored in the subscriber identity module (SIM) a mobile station can only be operated if a SIM with a valid IMSI is inserted into equipment with a valid IMEI. MCC (3)+MNC (2)+MSIN (10) - 15 digits

TMSI - the VLR, which is responsible for the current location of a subscriber, can assign a temporary mobile subscriber identity (TMSI) which has only local significance in the area handled by the VLR. It is stored on the network side only in the VLR and is not passed to the HLR. 4 octets

IMEI - The international mobile station equipment identity (IMEI) uniquely identifies a mobile station internationally. It is a kind of serial number. The IMEI is allocated by the equipment manufacturer and registered by the network operator and registered by the network operator who stores it in the EIR. By means of IMEI one recognizes obsolete, stolen or non-functional equipment. TAC+FAC+SNR+Spare - 15 digits.

LAI - Each LA of a PLMN has its own identifier. The Location Area Identifier (LAI) is also structured hierarchically and internationally unique as follows: MCC+MNC+LAC.

BASE STATION SYSTEM (BSS)The BSS is a set of BS equipments (such as transceivers and controllers) that is in view by the MSC through a single A-interface as being the entity responsible for communicating with MSs in a certain area. The radio equipment of a BSS may be composed of one or more cells. A BSS may consist of one or more BS. The interface between BSC and BTS is designed as an A-bits interface. The BSS includes two

types of machines: the BTS in contact with the MSs through the radio interface and the BSC, the latter being in contact with the MSC. The function split is basically between transmission equipment, the BTS, and managing equipment at the BSC. A BTS compares radio transmission and reception devices, up to and including the antennas, and also all the signal processing specific to the radio interface. A single transceiver within BTS supports eight basic radio channels of the same TDM frame. A BSC is a network component in the PLMN that function for control of one or more BTS. It is a functional entity that handles common control functions within a BTS.

Functions of BTS As stated, the primary responsibility of the BTS is to transmit and receive radio signals from a mobile unit over an air interface. To perform this function completely, the signals are encoded, encrypted, multiplexed, modulated, and then fed to the antenna system at the cell site. Transcoding to bring 13-kbps speech to a standard data rate of 16 kbps and then combining four of these signals to 64 kbps is essentially a part of BTS, though it can be done at BSC or at MSC. The voice communication can be either at a full or half rate over logical speech channel. In order to keep the mobile synchronized, BTS transmits frequency and time synchronization signals over frequency correction channel (FCCH) and BCCH logical channels. The received signal from the mobile is decoded, decrypted, and equalized for channel impairments.

BTS-BSC Configurations

There are several BTS-BSC configurations: single site, single cell; single site, multicell and multisite, multicell. These configurations are chosen based on the rural or urban Application. These configurations make the GSM system economical since the operation has options to adapt the best layout based on the traffic requirement. Thus, in some sense, system optimization is possible by the proper choice of the configuration. These include Omni directional rural configuration where the BSC and BTS are on the same site; chain and multi-drop loop configuration in which several BTSs are controlled by a single remote BSC with a chain or ring connection topology; rural star configuration in which several BTSs are connected by individual lines to the same BSC; and sector zed urban configuration in which three BTSs share the same site and are controlled by either a collocated or remote BSC. In rural areas, most BSs are installed to provide maximum coverage rather than maximum capacity.

Transcoder Depending on the relative costs of a transmission plant for a particular cellular operator, there may be some benefit, for larger cells and certain network topologies, in having the transcoder either at the BTS, BSC or MSC location. If the transcoder is located at MSC, they are still considered functionally a part of the BSS. This approach allows for the maximum of flexibility and innovation in optimizing the transmission between MSC and BTS.

The transcoder is the device that takes 13-Kbps speech or 6.5-Kbps data, and then multiplexes four of them to convert into standard 64-Kbps data. These are called Full Rate and Half Rate encoding respectively. First, the 13 Kbps or the data at 6.5 Kbps are brought up to the level of 16 Kpbs by inserting additional synchronizing data to make up the difference between a 13-Kbps speech or lower rate data, and then four of them are combined in the transcoder to provide 64 Kpbs channel within the BSS. Four traffic channels can then be multiplexed on one 64-Kpbs circuit. Thus, the TRAU output data rate is 64 Kpbs. Then, up to 30 such 64-Kpbs channels are multiplexed onto a 2.048 Mbps.

Base Station Controller (BSC)

The BSC is connected to the MSC on one side and to the BTS on the other. The BSC performs the Radio Resource (RR) management for the cells under its control. It assigns and release frequencies and timeslots for all MSs in its own area. The BSC performs the intercell handover for MSs moving between BTS in its control. It also

reallocates frequencies to the BTSs in its area to meet locally heavy demands during peak hours or on special events.

The BSC controls the power transmission of both BSSs and MSs in its area. The minimum power level for a mobile unit is broadcast over the BCCH. The BSC provides the time and frequency synchronization reference signals broadcast by its BTSs. The BSC also measures the time delay of received MS signals relative to the BTS clock. If the received MS signal is not centered in its assigned timeslot at the BTS, the BSC can direct the BTS to notify the MS to advance the timing such that proper synchronization takes place. The BSC may also perform traffic concentration to reduce the number of transmission lines from the BSC to its BTSs.

NSS: Network and Switching Subsystem Call control identification of the subscriber establishing a call and release of the connection after the call is over Mobility management taking care of the location of the subscribers before, during and after a call Collecting the charging information about a call number of the caller and of the called subscriber length and type of the provided services Transfer the acquired charging information to the Billing centre Signalling with other networks and BSS through the different interfaces Subscriber data handling Data storage permanently or temporarily in some databases OMCR: - It is used to monitor and maintain the alarms of the system.

SWITCHING SUBSYSTEMS: MOBILE SWITCHING CENTER AND GATEWAY SWITCHING CENTER

The network and the switching subsystem together include the main switching functions of GSM as well as the databases needed for subscriber data and mobility

management (VLR). The main role of the MSC is to manage the communications between the GSM users and other telecommunication network users. The basic switching function is performed by the MSC, whose main function is to coordinate setting up calls to and from GSM users. The MSC has interface with the BSS on one side (through which MSC VLR is in contact with GSM users) and the external networks on the other (ISDN/PSTN/PSPDN). The main difference between an MSC and an exchange in a fixed network is that the MSC has to take into account the impact of the mobile nature of the subscribers and has to perform, in addition, at least, activities required for the location registration and handover.

Functions of MSCAs stated, the main function of the MSC is to coordinate the set up of calls between GSM mobile and PSTN users. Specifically, it performs functions such as paging, resource allocation, location registration, and encryption. Specifically, the call-handling function of paging is controlled by MSC. MSC coordinates the set up of call to and from all GSM subscribers operating in its areas. The dynamics allocation of access resources is done in coordination with the BSS. More specifically, the MSC decides when and which types of channels should be assigned to which MS. The channel identity and related radio parameters are the responsibility of the BSS, the MSC provides the control of inter-working with different networks. It is transparent for the subscriber authentication procedure. The MSC supervises the connection

transfer between different BSSs for MSs, with an active call, moving from one call to another.

Visitor Location Register (VLR) The VLR is collocated with an MSC. An MS roaming in an MSC area is controlled by the VLR responsible for that area. When an MS appears in an LA, it starts a registration procedure. The MSC for that area notices this registration and transfers to the VLR the identity of the LA where the MS is situated. A VLR may be in charge of one or several MSC LA’s. The VLR constitutes the databases that support the MSC in the storage and retrieval of the data of subscribers present in its area. When an MS enters the MSC area borders, it signals its arrival to the MSC that stores it’s identify in the VLR. The information necessary to manage the MS is contained in the HLR and is transferred to the VLR so that they can be easily retrieved if so required.

Home Location Register (HLR) The HLR is a database that permanently stores data related to a given set of subscribers. The HLR is the reference database for subscriber parameters. Various identification numbers and addresses as well as authentication parameters, services subscribed, and special routing information are stored. Current subscriber status including a subscriber’s temporary roaming number and associated VLR if the mobile is roaming, are maintained.

Authentication Center (AuC)

The AuC stores information that is necessary to protect communication through the air interface against intrusions, to which the mobile is vulnerable. The legitimacy of

the subscriber is established through authentication and ciphering, which protects the user information against unwanted disclosure. Authentication information and ciphering keys are stored in a database within the AuC, which protects the user information against unwanted disclosure and access. In the authentication procedure, the key Ki is never transmitted to the mobile over the air path, only a random number is sent. In order to gain access to the system, the mobile must provide the correct Signed Response (SRES) in answer to a random number (RAND) generated by AuC.

Equipment Identity Register (EIR)

EIR is a database that stores the IMEI numbers for all registered ME units. The IMEI uniquely identifies all registered ME. There is generally one EIR per PLMN. It interfaces to the various HLR in the PLMN. The EIR keeps track of all ME units in the PLMN. It maintains various lists of message. The database stores the ME identification and has nothing do with subscriber who is receiving or originating call. There are three classes of ME that are stored in the database, and each group has different characteristics.

White List : contains those IMEIs that are known to have been assigned to valid MS’s. This is the category of genuine equipment.

Black List : contains IMEIs of mobiles that have been reported stolen. Gray List : contains IMEIs of mobiles that have problems (for example,

faulty software, and wrong make of the equipment). This list contains all MEs with faults not important enough for barring.

Interworking Function (IWF ) GSM provided a wide range of data services to its subscribers. The GSM system interface with the various forms of public and private data networks currently available it is the job of the IWF to provide this interfacing capability. The IWF, which in essence is a part of MSC, provides the subscriber with access to data rate

and protocol conversion facilities so that data can be transmitted between GSM Data Terminal Equipment (DTE) and a land-line DTE.

GSM Network Overview

A GSM system is basically designed as a combination of three major subsystems: the network subsystem, the radio subsystem, and the operation support subsystem. In order to ensure that network operators will have several sources of cellular infrastructure equipment, GSM decided to specify not only the air interface, but also the main interfaces that identify different parts. There are three dominant interfaces, namely, an interface between MSC and BSC, known as A-interface; an interface between BSC and BTS, known as A-bits interface; an interface between MS and BTS, known as Um interface.

The following logical channels are defined in GSM

Traffic Channel: TCHF: Full rate traffic channel. TCHh: Half rate traffic channel.

Broadcast Channels: BCCH : Broadcast Network information, e.g. for describing the current

control channel structure: The BCCH is a point-to-multipoint channel (BSS-to-MS).

SCH : Synchronisation of the MSs. FCHMS : frequency correction.

Common Control Channels: AGCH : Acknowledge channel requests from MS and allocate a SDCCH. PCHMS : terminating call announcement. RACHMS : access requests, response to call announcement, location

update, etc. CBCH : Cell Broadcast Channel is an optional GSM Phase II.

Implementations for SMS broadcast messages, for example road traffic reports or network engineering messages.

CHANNELS DIGRAM

The first channel type carries speech and data, and the other types control information (signaling).

CALL PROCESSING

Call Processing Procedures under different cases:

Case- I: ND Mobile moves to CA and Powers on MS

Case-II: ND PSTN Subscriber Dials ND Mobile Subscriber in ND.

Case- III: ND PSTN Subscriber Dials CA Mobile Subscriber in CA.

Case-IV: ND PSTN Subscriber Dials ND Mobile Subscriber in CA.

Case- V: CA PSTN Subscriber Dials ND Mobile Subscriber in CA.

Case- VI: CA Mobile Subscriber Dials ND Mobile Subscriber in ND.

Case- VII: CA Mobile Subscriber Dials ND Mobile Subscriber in CA.

Case- VIII: ND Mobile Subscriber in CA Dials ND Mobile in ND.

Case- IX: CA Mobile in ND Dials ND Mobile Subscriber in CA.

FUTURE

GPRS

General Packet Radio Service (GPRS) is a new non-voice value added service that allows information to be sent and received across a mobile telephone network. It supplements today's Circuit Switched Data and Short Message Service. GPRS is NOT related to GPS (the Global Positioning System), a similar acronym that is often used in mobile contexts.

General Packet Radio Service (GPRS) enabled networks offer 'always-on', higher capacity, Internet-based content and packet-based data services. This enables services such as color Internet browsing, e-mail on the move, powerful visual communications, multimedia messages and location-based services.

 GPRS is used to implement high-speed data transmission between the MS and some other party. GPRS utilizes multiple BTSs in the same BSS. The MS sends different packets to different BTSs, which are reconstructed at the SGSN. This enables the MS to use a higher transmission speed than one transmission channel can handle.

3-GSM

3GSM is the latest addition to the GSM family. 3GSM is about having third generation mobile multimedia services available globally. 3GSM focuses on visionary communications, in more ways than one. It's about the new visual ways in which people will communicate and the unique vision of the GSM community, which has always focused on the future needs of our customers.

The second Generation Systems have certain limitations. These include no global standards, low information bit rate, low voice quality and no support of Video. Some of these limitations can be overcome in 2.5 G systems that include General Packet Radio System (GPRS).

The next step towards 3G for GSM/GPRS networks is Enhanced Data for GSM Evolution (EDGE). This will increase the data rate up to 384 kbps bundling up to 8 channels of 48 kbps per channel. It is based on a new modulation scheme that allows a much higher bit rate across the air interface called 8-PSK modulation.