What is the meaning of subchannels in GSM ?

What is the meaning of a subchannel in GSM. For example for SDCCH we have 4 subchannels in combined mode does it mean that they are acually 4 diff pairs carrying diff signaling info for diff calls going on.

and also what does it mean "sub-channel number on this time-slot" ??

Re: subchannels in GSM

Subchanel is meaning that phisical chanel ( frequency chanel and time-slot) can carry depending on configuration a variable logical chanels.(traffic, signaling). In wide sense this chanels mapping into frames, multiframes... And if phisical chanel ( for exemple 0 time-slot) is assign as signaling ( it can be configurated as BCCH+CCCH or BCCH+CCCH+SDCCH or SDCCH+SACCH according to signaling traffic) he carry variable signaling chanels (FCCH, BCCH, SDCCH) at different time withing one multiframe. For example with BCCH+CCCH configuration FCCH appear every 10 frame in 51 multiframe and in SDCCH+SACCH conf. (SDCCH/8) one 51 multiframe carry 8 SDCCH chanels, each has 4 frames. SDCCH0 appear in frames 1-4, SDCCH1 in 5-8 etc.

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Re: subchannels in GSM

udit said:

What is the meaning of a subchannel in GSM. For example for SDCCH we have 4 subchannels in combined mode does it mean that they are acually 4 diff pairs carrying diff signaling info for diff calls going on.

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it mean that there are 4 different channels, combinely called SDCCH.


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