All About GSM

GSM

1. formerly: Groupe Spéciale Mobile (founded 1982)
2. now: Global System for Mobile Communication
3. Pan-European standard (ETSI, European Telecommunications Standardisation Institute)
4. simultaneous introduction of essential services in three phases (1991, 1994, 1996) by the European telecommunication administrations (Germany: D1 and D2)  seamless roaming within Europe possible
5. today many providers all over the world use GSM (more than 130 countries in Asia, Africa, Europe, Australia, America)
6. more than 100 million subscribers

Performance characteristics of GSM

Communication

• mobile, wireless communication; support for voice and data services

Total mobility

• international access, chip-card enables use of access points of different providers

Worldwide connectivity

• qone number, the network handles localization

High capacity

• qbetter frequency efficiency, smaller cells, more customers per cell High transmission quality
• high audio quality and reliability for wireless, uninterrupted phone calls at higher speeds (e.g., from cars, trains)

Security functions

• access control, authentication via chip-card and PIN

Disadvantages of GSM

There is no perfect system!!

• no end-to-end encryption of user data
• no full ISDN bandwidth of 64 kbit/s to the user, no transparent B-channel
• reduced concentration while driving
• electromagnetic radiation
• abuse of private data possible
• roaming profiles accessible
• high complexity of the system
• several incompatibilities within the GSM standards

GSM: Mobile Services -> GSM offers

several types of connections

=> voice connections, data connections, short message service

• multi-service options (combination of basic services)

Three service domains

• Bearer Services
• Telematic Services
• Supplementary Services

Architecture of the GSM system

GSM is a PLMN (Public Land Mobile Network)

several providers setup mobile networks following the GSM standard within each country

1. components :

• MS (mobile station)
• BS (base station)
• MSC (mobile switching center)
• LR (location register)

2. subsystems :

• RSS (radio subsystem): covers all radio aspects
• NSS (network and switching subsystem): call forwarding, handover, switching
• OSS (operation subsystem): management of the network