GSM Tecnology

The world's most popular standard for mobile telephone systems is Global System for Mobile Communications, or GSM (originally from Groupe Spécial Mobile). It is used by over 1.5 billion people all around the world, This ubiquity enables subscribers use their phones throughout the world, which is enabled with international roaming arrangements between mobile network operators. It is also considered a second generation (2G) mobile phone system as its differs from its predecessor technologies in both signaling and speech channels which are digitalized.

The European Conference of Postal and Telecommunications Administrations (CEPT) created the Groupe Spécial Mobile (GSM) in the year 1982, to develop a standard for a mobile telephone system that could be used across Europe. Later in 1987 a memorandum of understanding was signed by 13 countries to develop a common cellular telephone system across Europe and then in 1989 GSM responsibility was transferred to the European Telecommunications Standards Institute (ETSI) and phase I of the GSM specifications were published in 1990. The first GSM network was launched in 1991 by Radiolinja in Finland with network infrastructure provided by Telenokia and Siemens. And by the end of 1993, over a million subscribers were using GSM phone networks being operated by 70 carriers across 48 countries.

GSM is a cellular network, in which the mobile phones connect to it by searching for cells in the immediate vicinity. In this network there are five different cell sizes namely macro, micro, pico, femto and umbrella cells. Macro cells can be referred as cells where the base station antenna is installed on a mast or a building above average roof top level. Micro cells are cells whose antenna height is under average roof top level; they are typically used in urban areas. Pico cells are small cells whose coverage diameter is only of a few dozen meters and they are mainly used in indoors. Femto cells are cells designed for use in residential or small business environments and they connect to the service provider’s network via a broadband internet connection. Umbrella cells are used to cover shadowed regions of smaller cells and they fill in gaps in coverage between those cells. The key feature of GSM is the Subscriber Identity Module, commonly known as a SIM card, the SIM is a detachable smart card which contains the user’s subscription information and phone book. This allows the user to retain his or her information after switching handsets.

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