Synchronization Channel
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Synchronization Channel is a downlink only control channel used in GSM cellular telephone systems. It is part of the Um radio interface specification. The purpose of the SCH is to allow the mobile station (handset) to quickly identify a nearby cell (a BTS and synchronize to that BTS's TDMA structures. Each radio burst on the SCH contains:
- the current frame clock of the serving BTS,
- the Base station identity code (or BSIC), a truncated form of cell identity, and
- an extended Training Sequence that is easily detected with a matched filter.
The burst structure of the SCH is defined in GSM specification 05.03 section 4.7. The encoding of the frame clock is defined in GSM specification 04.08 section 9.1.30. The TDMA multiplexing pattern of the SCH is defined in GSM specification 05.02 clause 7 table 3.