GSM architecture : Base Station Subsystem (BSS) (1/3)

GSM architecture : Base Station Subsystem (BSS)

The Base Station Subsystem ensures as complete a network coverage as possible and
includes a large number of structurally organised radio cells. It consists of the following
elements:
• The Base Transceiver Station
• The Base Station Controller
and
• The Transcoder

The central element of one cell of this kind is a transmitting and receiving unit known as a
Base Transceiver Station (BTS). This makes the connection to the mobile station via the air
interface and controls the transceiver (TRX). The transceiver, the central functional unit of
the BTS, maintains calls to a maximum of 8 mobile stations via one frequency pair each. The
BTS is also responsible for the monitoring of the signal quality and the encoding and
modulation of useful signals. Via the A-bis interface, it forwards calls, signals and control
information destined for the OMS and the NSS to the Base Station Controller (BSC).