Base Transceiver Station (BTS)

Base Transceiver Station (BTS) – The BTS is the Mobile Station’s access point to the network. It is responsible for carrying out radio communications between the network and the MS. It handles speech encoding, encryption, multiplexing (TDMA), and modulation/demodulation of the radio signals. It is also capable of frequency hopping. A BTS will have between 1 and 16 Transceivers (TRX), depending on the geography and user demand of an area. Each TRX represents one ARFCN.
One BTS usually covers a single 120 degree sector of an area. Usually a tower with 3 BTSs will accommodate all 360 degrees around the tower. However, depending on geography and user demand of an area, a cell may be divided up into one or two sectors, or a cell may be serviced by several BTSs with redundant sector coverage.
A BTS is assigned a Cell Identity. The cell identity is 16-bit number (double octet) that identifies that cell in a particular Location Area. The cell identity is part of the Cell Global Identification (CGI), which is discussed in the section about the Visitor Location Register (VLR).

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