GSM

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GLOBAL SYSTEM FOR MOBILE (GSM) :

GLOBAL SYSTEM FOR MOBILE (GSM) PRESENTED BY: DHEERAJ RAJA ECE 4 th YEAR

GSM:

GSM What ? GSM: Global System for Mobile Communications. Formerly: Group Special Mobile When ? 1982: GSM created to set standard. 1988: Industrial development started. 1991: First system deployed. Why ? Higher digital voice quality. Low cost alternatives for making calls and sms .

GSM ARCHITECTURE:

GSM ARCHITECTURE BSS Abis MS BTS BSC MSC HLR AUC OMC VLR Other MSCs VLRs Other Networks EIR Other MSCs Um A B D C E F

MOBILE STATION:

MOBILE STATION MS consists of 2 parts: - Mobile Equipment - SIM Mobile Equipment: Hardware used by the subscriber to access the network. Uniquely identified by IMEI number. Subscriber Identity Module (SIM): Smartcard containing the International Mobile Subscriber Identity (IMSI). Allows user to send & receive calls and received other subscribed services.

BASE STATION SUB-SYSTEM (BSS):

BASE STATION SUB-SYSTEM (BSS) BSS connects the Mobile Station with MSC through A-interface. In charge of Transmission & Reception. Consists of 2 parts: - Base Transceiver Station (BTS) - Base Station Controller (BSC)

BASE TRANSCEIVER Station (BtS):

BASE TRANSCEIVER Station ( BtS ) Consists of TRAU (Transcoder/Rate Adapter Unit). Handles Speech Encoding, Encryption, Multiplexing and Modulation/ Demodulation of radio signals. Usually covers a single 120 degree sector of an area.

BASE STATION CONTROLLER (BSC):

BASE STATION CONTROLLER (BSC) Allocation of Channels. Frequency Administration. Controls the power transmission. Handovers from one BTS to another.

Network & sWITching SUB-system (NSS):

Network & sWITching SUB-system (NSS) Manages communication between the mobile user with the other users. Consists of different components as: - Mobile Switching Centre (MSC) - Gateway Mobile Switching Centre (GMSC) - HLR & VLR - AuC & EIR

MOBILE SWITCHING CEnTRE (MSC):

MOBILE SWITCHING CEnTRE (MSC) Heart of the GSM Network. Performs Call Routing, Call set-up and basic switching functions. Generates CDR for each & every call. Communicates with HLR, VLR & other MSCs.

Gateway mobile switching centre (GMSC):

Gateway mobile switching centre (GMSC) Functions as a gateway between 2 networks. Switch to the Public Switch Telephone Network (PSTN).

HLR &VLR:

HLR &VLR HLR contains a database for subscriber specific information such as IMSI, current location of the MS, roaming restrictions etc. VLR contains a temporary database about all active subscribers and always integrated with the MSC.

EIR &AUC:

EIR &AUC EIR is a database that keeps tracks of handsets on the Network using the IMEI number. It contains 3 lists: - White List - Grey List - Black List AuC handles the authentication and encryption task for the Network. It is mainly used for security reasons.

OPERATION & MAINTENANCE CENTRE (OMC):

OPERATION & MAINTENANCE CENTRE (OMC) All the networks elements are connected to OMC. Keeps records of all the faults occurred. Provides a network overview and support the maintenance activities of different operations.

GSM FREQUENCY:

GSM FREQUENCY In India, GSM Network operates in 900 MHz & 1800 MHz bands. GSM- 900 uses - 890-915 MHz to send information from Mobile Station to the Base Station(Uplink). - 935-960 MHz for the other direction (Downlink). - Duplex Spacing is 45 MHz. GSM-1800 uses - 1710-1785 MHz for Uplink. - 1805-1880 MHz for downlink. - Duplex Spacing is 95 MHz. Providing 124 RF channels (Channel Numbers 1to 124) spaced at 200 KHz.

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