Synchronization Channel is a downlink only control channel used in
GSM cellular telephone systems.
It is part of the
Um air interface specification.
The purpose of the SCH is to allow the mobile station (handset) to quickly identify a nearby cell (a
BTS
BTS (), also known as the Bangtan Boys, is a South Korean boy band formed in 2010 and debuting in 2013 under Big Hit Entertainment. The septet—consisting of members Jin, Suga, J-Hope, RM, Jimin, V, and Jungkook—co-writes and co-produ ...
) 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
In computer networks, a syncword, sync character, sync sequence or preamble is used to synchronize a data transmission by indicating the end of header information and the start of data. The syncword is a known sequence of data used to identif ...
that is easily detected with a matched filter.
When mobile turns on after getting FCCH it waits for getting SCCH which is to synchronise mobile's oscillator frequency with the frequency of the Base channel.
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.
The
GSM Synchronization Burst Contains a Training Sequence of 64 bits that is used to facilitate synchronization.
* Sync bits are known by both the
BTS
BTS (), also known as the Bangtan Boys, is a South Korean boy band formed in 2010 and debuting in 2013 under Big Hit Entertainment. The septet—consisting of members Jin, Suga, J-Hope, RM, Jimin, V, and Jungkook—co-writes and co-produ ...
and the mobile.
* Detecting where the synchronization burst occurs in time allows the
MS to synchronize with the
BTS
BTS (), also known as the Bangtan Boys, is a South Korean boy band formed in 2010 and debuting in 2013 under Big Hit Entertainment. The septet—consisting of members Jin, Suga, J-Hope, RM, Jimin, V, and Jungkook—co-writes and co-produ ...
baud clock and frame clock.
* Tracking the drift from SCH burst to SCH burst can be used by the mobile station to fine-tune receiver clock.
GSM standard
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