Page 18 - Mobile Computing

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Channel structure in GSM

Global System for Mobile Communication (GSM) is the most popular technology
for mobile phones now days.). GSM a standard developed by the European
Telecommunications Standards Institute (ETSI). Firstly, its name was the group
special mobile (GSM) and later named as global system for mobile
communications (GSM). It is a digital mobile telephony system that is widely
used in Europe.

The main motto of GSM was to provide a mobile phone system that allows users

to roaming facility throughout Europe. It is a second generation (2G) standard for
mobile networks and uses digital techniques. GSM uses the Frequency Division
Multiple Access (FDMA) and Time Division Multiple Access (TDMA).

GSM provides three different categories of services:

 Bearer.

 Tele
 Supplementary services

Bearer Service or Data Services
Bearer services permit transparent and non-transparent, synchronous or
asynchronous data transmission. It allows data transmission between network

interfaces. By using data services, a user can to transmit appropriate signals
between user network interfaces.

Teleservices or Telephony Services:

GSM provides the following main Telephony Services.

 Voice Calls
 Videotext

 Short Text Messages

Supplementary services
GSM provides the following Supplementary services

 Multiparty Service or conferencing
 Call Waiting.
 Call Hold

 Call Forwarding
 Number Identification.
 Closed User Groups (CUGs).