Global System for Mobile Communication (GSM)
Global System for Mobile Communication (GSM) is a second generation (2G) standard for mobile networks developed by the European Telecommunications Standards Institute (ETSI) and deployed in Finland in December 1991. As of 2014, it has become the global standard for mobile communications with over 90% market share, operating in over 219 countries and territories.
GSM is working using the technique for transmitting signal called narrow band Time Division Multiple Access (TDMA). It supports voice calls and data transfer speeds of up to 9.6 kbps, together with the transmission of SMS.
The GSM standard operates on three different carrier frequencies:
- 900 MHz band
- 1800 MHz band
- 1900 MHz band
Features of GSM
- High-quality speech
- Good spectrum efficiency
- Integrated Services Digital Network (ISDN) and other telephone company
- services compatibility
- Support for new services
- International roaming
- Low-cost mobile sets and base stations.
GSM network can be divided into three,
- Mobile Station(MS)
- Base Station Subsystem(BBS)
- Network Subsystem
1.Mobile Station (MS)
Mobile Station consist of Mobile Equipment(ME) and Subscriber Identity Module(SIM). ME is produced by many different manufactures but uniquely identified by International Mobile Equipment Identity (IMEI). SIM is a smart card that provides personal mobility, so that the user can have access to subscribed services irrespective of a specific terminal. By inserting the SIM card into another GSM terminal, the user is able to receive calls at that terminal, make calls from that terminal, and receive other subscribed services.
2.Base Station Sub system (BBS)
BBS consist of two parts, Base Transceiver Station (BTS) and the Base Station Controller (BSC). The Base Transceiver Station houses the radio transceivers that define a cell and handles the radio-link protocols with the Mobile Station. Requirements for a BTS are ruggedness, reliability, portability, and minimum cost.
3.Network Sub system
The central component of the network subsystem is the mobile services switching center(MSC). It provides the main control and interfacing for the whole mobile network. MSC acts like a normal switching node of the PSTN (Public Switched Telephone Network) or ISDN (Integrated Services Digital Network) and connects the mobile signal to these fixed networks. It also provides functionality needed to handle a mobile subscriber, such as registration, authentication, location updating, handovers and call routing to a roaming subscriber.
- Improved battery life
- A wide variety of handsets and accessories
- Security against fraud
- Efficient use of spectrum
- Short messaging and caller ID
- Crisper, cleaner quieter calls
- International roaming capability
- High stability mobile fax