The Global System for Mobile Communications

The Global System for Mobile Communications (GSM) is a protocol for handling voice and data transfer over mobile phone networks. GSM is the most widely used mobile phone network standard in the world. Its widespread use makes it easy for people to use their existing phones on multiple networks in different nations.
 

History of GSM

The Global System for Mobile Communication was established in Europe in 1982 to help standardize the technology for cellular networks throughout the continent. In 1990, the first standards for GSM were published, and the first active GSM network was launched in Finland in 1991. By 1993, more than 1 million subscribers were active on a GSM network. Today, it is the most widely used protocol, with more than 2 billion users across 212 countries.

GSM differs from previous cellular technologies in that it handles all data transfer digitally. This allows for clearer calls and additional technologies such as short message service (SMS), more commonly known as text messaging.
The digital structure of GSM networks also allows for additional technologies, such as Enhanced Data Rates for GSM Evolution (EDGE), which allows packet data transfer for multimedia messaging and Internet access via mobile phones.

How GSM Works

GSM is a set of guidelines for building and operating a cellular network. The idea behind GSM was to limit builders as little as possible in design while establishing a basis for the greatest interoperability. This flexibility has allowed GSM networks to flourish because it keeps costs lower than proprietary systems.

GSM operates on and one of four bandwidths. The most common bandwidths are 900 MHz and 1800 MHz. In some countries where those bandwidths were already in use prior to GSM, GSM can operate on the 850 MHz and 1900 MHz frequencies.

A GSM phone uses codecs (a device or program capable of performing transformations on a data stream or signal) to break the data into packets of either 6 kbit/s or 13 kbit/s that are transmitted via the Time Division Multiple Access (TDMA) protocol through the network.

A GSM network, while unseen, is large and complicated, due to all the services it must handle. It is broken down into three basic systems:

  • The base station system handles all radio and transmission functions.
  • The operation and support system is used to maintain and monitor the network.
  • The switching system is responsible for processing calls and basic functions.
All of these systems combine to support each of the functions available on a GSM phone.

GSM was built with a moderate security level. The system uses an encryption key between the phone and base station. It authenticates users as they access a network but does not authenticate the network to the user.

Disadvantages of GSM

GSM has some disadvantages when compared to some of the newer mobile network technologies. GSM is known as a second-generation system. Third-generation systems feature higher data transfer rates. Higher transfer rates allow greater call quality and additional services such as high-quality streaming video and high-speed Internet capabilities.