The TDMA/FDMA multiplexing is used in GSM, the
information needed in the synchronization between MS and BTS is provided by
FCCH+SCH.
The MS determines the frequency of the BCCH carrier by
searching for the frequency correction Burst transmitted via FCCH; then it
finds the SCH (synchronization channel) according to the relationship between
SCH and FCCH and decodes the current frame number and BSIC for synchronization with BTS. Furthermore, it
determines whether the cell is barred or not and decodes the system information
on BCCH.
In the structure diagram of extended BCCH, except that
the F and S timeslots are replaced by Idle timeslots, the rest of the
structures are the same as that of the main BCCH.
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