Post By: Hanan Mannan
Contact Number: Pak (+92)-321-59-95-634
-------------------------------------------------------

GSM - Overview

What is GSM?

If you are in Europe, Asia or Japan and using a mobile phone, then most probably you must be using GSM technology in your mobile phone.

• GSM stands for Global System for Mobile Communication and is an open, digital cellular technology used for transmitting mobile voice and data services.
• The GSM emerged from the idea of cell-based mobile radio systems at Bell Laboratories in the early 1970s.
• The GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard.
• The GSM standard is the most widely accepted standard and is implemented globally.
• The GSM is a circuit-switched system that divides each 200kHz channel into eight 25kHz time-slots. GSM operates in the 900MHz and 1.8GHz bands in Europe and the 1.9GHz and 850MHz bands in the US.
• The GSM is owning a market share of more than 70 percent of the world's digital cellular subscribers.
• The GSM makes use of narrowband Time Division Multiple Access (TDMA) technique for transmitting signals.
• The GSM was developed using digital technology. It has an ability to carry 64 kbps to 120 Mbps of data rates.
• Presently GSM supports more than one billion mobile subscribers in more than 210 countries throughout the world.
• The GSM provides basic to advanced voice and data services including Roaming service. Roaming is the ability to use your GSM phone number in another GSM network.

A GSM digitizes and compresses data, then sends it down through a channel with two other streams of user data, each in its own time slot. It operates at either the 900 MHz or 1,800 MHz frequency band.

Why GSM?

The GSM study group aimed to provide the followings through the GSM:

• Improved spectrum efficiency.
• International roaming.
• Low-cost mobile sets and base stations (BSs).
• High-quality speech.
• Compatibility with Integrated Services Digital Network (ISDN) and other telephone company services.
• Support for new services.

GSM Brief History:

Following table shows many of the important events in the rollout of the GSM system; other events were introduced, but had less significant impact on the overall systems.

Years	Events
1982	CEPT establishes a GSM group in order to develop the standards for a pan-European cellular mobile system.
1985	A list of recommendations to be generated by the group is accepted.
1986	Field tests are performed to test the different radio techniques proposed for the air interface.
1987	Time Division Multiple Access (TDMA) is chosen as the access method (with Frequency Division Multiple Access [FDMA]). The initial Memorandum of Understanding (MoU) is signed by telecommunication operators representing 12 countries.
1988	GSM system is validated.
1989	The responsibility of the GSM specifications is passed to the European Telecommunications Standards Institute (ETSI).
1990	Phase 1 of the GSM specifications is delivered.
1991	Commercial launch of the GSM service occurs. The DCS1800 specifications are finalized.
1992	The addition of the countries that signed the GSM Memorandum of Understanding takes place. Coverage spreads to larger cities and airports.
1993	Coverage of main roads' GSM services starts outside Europe.
1994	Data transmission capabilities launched. The number of networks rises to 69 in 43 countries by the end of 1994.
1995	Phase 2 of the GSM specifications occurs. Coverage is extended to rural areas.
1996	June: 133 network in 81 countries operational.
1997	July: 200 network in 109 countries operational, around 44 million subscribers worldwide.
1999	Wireless Application Protocol came into existence and 130 countries operational with 260 million subscribers.
2000	General Packet Radio Service(GPRS) came into existence.
2001	As of May 2001, over 550 million people were subscribers to mobile telecommunications.