GSM (Global System for Mobile communications) is a widely adopted wireless telecommunications standard for digital cellular services. Initially focused on voice and low-speed data, it later evolved to support higher data rates and packet-switched data. GSM operates on TDMA technology and is globally prominent, enabling widespread roaming. It utilizes various frequency ranges, including 900 MHz, 1800 MHz, and 1900 MHz, with additional limited use of 850 MHz and 450 MHz bands, facilitating international mobile communication.
The table provides an overview of various GSM frequency bands, including their names, uplink and downlink frequencies, and specific usage remarks:
- GSM400 (GSM450): Uplink 450.4 – 457.6 MHz, Downlink 460.4 – 467.6 MHz
- GSM480: Uplink 478.8 – 486.0 MHz, Downlink 488.8 – 496.0 MHz
- GSM700 (GSM750): Uplink 777.0 – 792.0 MHz, Downlink 747.0 – 762.0 MHz
- GSM850: Uplink 824.0 – 849.0 MHz, Downlink 869.0 – 894.0 MHz (Used in the Americas and Asia)
- GSM900:
- Primary GSM: Uplink 890.0 – 915.0 MHz, Downlink 935.0 – 960.0 MHz (Original GSM band)
- Extended GSM: Uplink 880.0 – 890.0 MHz, Downlink 925.0 – 935.0 MHz (Extension of the primary band)
- GSM Rail: Uplink 876.0 – 880.0 MHz, Downlink 921.0 – 925.0 MHz (Especially used for railways)
- GSM1800 (DCS1800): Uplink 1710 – 1785 MHz, Downlink 1805 – 1880 MHz
- GSM1900 (PCS1900): Uplink 1850 – 1910 MHz, Downlink 1930 – 1990 MHz (Mainly used in the Americas).
In the GSM network infrastructure, Mobile Switching Centres (MSCs) are connected to and control 2 or 3 Base Station Controllers (BSCs). Each BSC, in turn, manages several Base Transceiver Stations (BTS). The allocation of specific radio frequencies for communication is determined by the Absolute Radio Frequency Channel Number (ARFCN). This hierarchical structure ensures the efficient management and connectivity of mobile communication within the GSM network.