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Global System for Mobile
Ø New rapidly expanding & successful technology.
Ø Fully Digitized technology for better speech quality.
Ø Available in almost every part of the world.
Ø Fully compatible with existing Fixed Line Network.
Ø Single number operation with World wide Roaming.
Ø Very well defined interfaces makes truly open system
Ø Encryption of user information
Ø Available versions, GSM 900, 1800 & 1900

Base Transceiver Station (BTS)
BTS
Antenna
Arrangement
Ø BTS has a set of Transceivers to talk to MS.
Ø One BTS covers one or more than one cell.
Ø Capacity of BTS depends on no of Transceivers.
Ø BTS is connected to BSC via A™bis interface.
Ø Transmission rate on A™bis is 2 Mbps (G.703).
Ø Interface between MS & BTS is called Air I/f.
Ø Transmission rate on Air interface is 13 Kbps.
Ø BTS controls RF parameters of MS.
Ø Each TRx has 8 TDMA channels to carry Voice & signalling.