15-11-2012, 03:51 PM
GSM – GLOBAL SYSTEM FOR MOBILE COMMUNICATION
gsm_introduction.ppt (Size: 585 KB / Downloads: 37)
HISTORY
Early 80’s Europe was experiencing rapid growth in the analog cellular telephone systems
1982 Conference of European Posts and Telegraphs (CEPT) GSM (Groupe Special Mobile) group was formed to study and develop a pan-European public land mobile system
GSM mandate was to develop a standard to be common for the countries that created it – provide service to the entire European continent
Phase I of GSM specifications was published in 1990
International demand was so great that the system name was changed from Groupe Special Mobile to Global Systems for Mobile Communications (still GSM)
Commercial service started in mid-1991
1992 first paying customers were signed up for service
By 1993 there were 36 GSM networks in 22 countries
Early 1994 there were 1.3 million subscribers worldwide
By 1996 there were more than 25 million subscribers worldwide
By October 1997 it had grown to more than 55 million subscribers worldwide
Building Blocks
AMPS – Advanced Mobile Phone System
TACS – Total Access Communication System
NMT – Nordic Mobile Telephone System
AMPS – Advanced Mobile Phone System
analog technology
used in North and South America and approximately 35 other countries
operates in the 800 MHz band using FDMA technology
System ArchitectureBase Station Subsystem (BSS)
Base Station Subsystem is composed of two parts that communicate across the standardized Abis interface allowing operation between components made by different suppliers
Base Transceiver Station (BTS)
Base Station Controller (BSC)
Base Transceiver Station (BTS)
Houses the radio transceivers that define a cell
Handles radio-link protocols with the Mobile Station
Speech and data transmissions from the MS are recoded
Requirements for BTS:
ruggedness
reliability
portability
minimum costs
Advantages of GSM
Crisper, cleaner quieter calls
Security against fraud and eavesdropping
International roaming capability in over 100 countries
Improved battery life
Efficient network design for less expensive system expansion
Efficient use of spectrum
Advanced features such as short messaging and caller ID
A wide variety of handsets and accessories
High stability mobile fax and data at up to 9600 baud
Ease of use with over the air activation, and all account information is held in a smart card which can be moved from handset to handset