Explain GSM frame hierarchy.

Mumbai University > Computer Engineering > Sem - 6 > Mobile communication and computing

Marks: 5 M

Year: May 2015

1 Answer

The GSM data transmission occurs in bursts where TDMA frames a transmitted. It is however organized in a hierarchical structure for efficient transmission and encryption.


  • A GSM frame is divided into eight time slots where each slot represents a physical TDM channel. Different types of data are transmitted in time slots. The total time required for a GSM time-slot to complete transmission with guard time is 577┬Ás.


  • Eight such time slots constitute together to form a frame.


  • In case of traffic channels and control channels associated with them, 26 frames create a Multiframe. (i.e TCH Multiframe)
  • In case of broadcast channels and control channels associated with them, 50 frames create a Multiframe. (i.e. BCH Multiframe)
  1. Superframe:
  • 51 TCH Multiframes combine together to form a Superframe.
  • In case of BCH Multiframes, 26 BCH Multiframes combine to form a Superframe.
  1. Hyperframe:
  • In both the cases of TCH and BCH , 2048 superframes create a Hyperframe.
  • A Hyperframe is the highest unit of GSM hierarchy.
  • It lasts for 3 hours 53 seconds 760 milliseconds.

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