the structure of "TCH + SACCH" is depend on timeslot?

Sylvain Munaut 246tnt at gmail.com
Wed May 30 13:04:40 UTC 2012


Hi

> I am studying the TCH channel, and read the BB source. I find that
> the structure of  "TCH + SACCH" is depend on ts.that is when the timeslot
> is even, the 12 of a TCH multiframes is SACCH,and the 25 is idle;and When
> the timeslot is odd, the 25 of a TCH multiframes is SACCH,and the12 is idle.
>
> is that right?

Yes

> if that`s right, why ?

To share the load. So that the BTS doesn't have to process all the
SACCH of all the TCH at the same time.

> I can`t find any Material about

GSM 05.02 Clause 7 Table 1 of 9, the SACCH/TF entries

Cheers,

   Sylvain




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