Thursday, October 21, 2010

The GSM Architecture- BSS

Base Station Subsystem

The Base Station Subsystem is mainly consists of two parts, the Base Transceiver Station (BTS) and the Base Station Controller (BSC). These communicate across the standardized Abis interface.

The Base Transceiver Station takes care of radio tranceivers that define a cell and handles the radio-link protocols with the Mobile phone. In a city like Mumbai there has to be a large number of BTSs deployed, thus the requirements for a BTS are ruggedness, reliability, portability, and minimum cost.

You may have also heard of an IBS( In-building solution). The next time you go out for dinner or to a hotel or even when you’re sitting in your office, look at the ceiling. You will find a conical shape. This is an IBS. It works as a BTS itself.

The BTS communicates with a BSC. A BSC will have multiple BTS. The Base Station Controller handles radio-channel setup, frequency hopping, and handovers.

So lets summarize:


1.Base Transceiver Station (BTS)
2.Base Station Controller (BSC)


  • Encodes,encrypts,multiplexes,modulates and feeds the RF signals to the antenna.
  • Frequency hopping
  • Communicates with Mobile station and BSC
  • Consists of Transceivers (TRX) units

  • Manages Radio resources for BTS
  • Assigns Frequency and time slots for all MS’s in its area
  • Handles call set up
  • Handover for each MS
  • Radio Power control
  • It communicates with MSC and BTS

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