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GSM

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The Global System for Mobile Communications, or GSM, is a family of standards for second-generation (2G) digital cellular networks. These protocols define how mobile devices, such as phones and broadband modems, communicate with a network. GSM was designed to replace the first-generation (1G) analog networks. It provides a digital, circuit-switched system optimized for full duplex voice telephony. This means two people can talk at the same time. To manage the airwaves, GSM uses time division multiple access (TDMA). This is a method where different users share the same frequency by taking turns in very fast, timed slots.

Gsm structures
Gsm structures

A GSM network is organized into several distinct parts to keep communication flowing. The first part is the Base Station Subsystem. This includes the base stations and their controllers. The second part is the Network and Switching Subsystem. This is often called the core network because it functions much like a fixed telephone network. There is also an optional GPRS Core Network. This part allows for packet-based Internet connections. Finally, the Operations Support System (OSS) handles the maintenance of the entire network.

Kathrein antenna
Kathrein antenna

To provide coverage, GSM uses a cellular structure. The network is divided into many areas called cells. These cells come in five different sizes to fit different environments. Macro cells use large antennas on tall masts or buildings. Micro cells are smaller and are often used in urban areas. Picocells are very small, covering only a few dozen meters, and are used for indoor coverage in places like airports. Femtocells are the smallest, designed for homes or small businesses using a broadband connection. Umbrella cells are used to fill in gaps or cover shadowed regions between other cells.

GSM-Telefone-1991
GSM-Telefone-1991

The history of GSM began with a push for European unity. In 1983, the CEPT committee began developing a digital standard. By 1987, representatives from 13 European countries signed a memorandum of understanding in Copenhagen. This agreement aimed to deploy a common system across Europe. This effort was guided by officials such as Armin Silberhorn, Stephen Temple, Philippe Dupuis, and Renzo Failli. In 1989, the committee moved to the European Telecommunications Standards Institute (ETSI). Thomas Haug and Philippe Dupuis later received the James Clerk Maxwell medal for their leadership in this development.

Dupuis Haug GSM around 1990
Dupuis Haug GSM around 1990

GSM saw rapid global growth after its first implementation in Finland in December 1991.

Bosch CarTel T
Bosch CarTel T

While some believe the first call happened in July 1991, a Nokia engineer named Pekka Lonka claimed he made the first test call earlier that year. By 1995, the number of worldwide subscribers exceeded 10 million. This number grew to 100 million by 1998 and reached 1 billion by 2004. By 2006, there were over 2 billion GSM subscribers globally. This made it much larger than its competitor, CDMA. By the mid-2010s, GSM held over 90% of the market share.

Icons on GSM mobile phone Siemens S4 (1996)
Icons on GSM mobile phone Siemens S4 (1996)

As technology progressed, the GSM standard evolved to include more than just voice. It first expanded to include data through circuit-switched transport. Later, it added packet data transport via GPRS and then EDGE. In 1996, pre-paid GSM SIM cards were launched to make service more accessible.

Nano Sim
Nano Sim

The standard also operates on various frequency bands. Most 2G networks use the 900 MHz or 1800 MHz bands. However, in the United States and Canada, the 850 MHz and 1900 MHz bands are often used instead.

While GSM was a massive success, it is now being phased out. Starting in the late 2010s, many carriers began shutting down their 2G networks. Telstra in Australia was the first to decommission a GSM network in December 2016. This was followed by AT&T Mobility in the United States in 2017. GSM's specifications eventually passed to the 3GPP body in 2000. This group also developed 3G, 4G, and 5G standards. Although these newer generations are not part of the GSM standard, the term "GSM" is still used as a generic name for many mobile technologies.

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🖼️ Images & Media (7)
File:Dupuis Haug GSM around 1990.jpg
Dupuis Haug GSM around 1990.jpg
File:Bosch CarTel T.jpg
Bosch CarTel T.jpg
File:GSM-Telefone-1991.jpg
GSM-Telefone-1991.jpg
File:Icons on GSM mobile phone Siemens S4 (1996).jpg
Icons on GSM mobile phone Siemens S4 (1996).jpg
File:Gsm structures.svg
Gsm structures.svg
File:Kathrein antenna.jpg
Kathrein antenna.jpg
File:Nano Sim.jpg
Nano Sim.jpg
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