18-09-2014, 09:55 AM
GSM
GSM.pptx (Size: 319.81 KB / Downloads: 11)
INTRODUCTION
Global System for Mobile (GSM) is a second generation cellular standard developed to cater voice services and data delivery using digital modulation.
Aim Of GSM is to replace the incompatible analog system .
Today many providers all over the world use GSM (more than 135 countries in Asia, Africa, Europe, Australia, America)
Base Station Subsystem
Base Station Subsystem is composed of two parts :
1) Base Transceiver Station (BTS)
2) Base Station Controller (BSC)
Base Transceiver Station (BTS)
Houses the radio transceivers that define a cell
Handles radio-link protocols with the Mobile Station
GSM SPECIFICATIONS
GSM systems use radio frequencies between 890-915 MHz for receive and between 935-960 MHz for transmit.
RF carriers are spaced every 200 kHz, allowing a total of 124 carriers for use.
An RF carrier is a pair of radio frequencies, one used in each direction.
Transmit and receive frequencies are always separated by 45 MHz .
Advantages of GSM over Analog system
Capacity increases
Reduced RF transmission power and longer battery life.
International roaming capability.
Better security against fraud (through terminal validation and user authentication.
Future Of GSM
2nd Generation
GSM -9.6 Kbps (data rate)
2.5 Generation ( Future of GSM)
HSCSD (High Speed circuit Switched data)
Data rate : 76.8 Kbps (9.6 x 8 kbps)
GPRS (General Packet Radio service)
Data rate: 14.4 - 115.2 Kbps
EDGE (Enhanced data rate for GSM Evolution)
Data rate: 547.2 Kbps (max)
3 Generation
WCDMA(Wide band CDMA)
Data rate : 0.348 – 2.0 Mbps