We have scenario here where in TCH assignment phase MS has sent Assignment Complete on layer 3, but on layer 2 there is no response to SABM frames sent by MS, also MS doesn’t sends I-CMD immediately after SABM and keeps on sending SABM again and again with time frame of T200,and thus Assignment failure is sent by MS exactly after T200S expiry( after N200+1)=6 times.
Please can you help me clarify the following doubts:
1) Why during TCH assignment phase T200_S came into picture. I can confirm the same as from layer 2 trace we see that Assignment failure is sent exactly after N200+1 times(6 times here).N200 for SACCH associated with SDCCH is 5 and N200 for FACCH/FR=34 and FACCH/HR=29 associated.
My doubt is for TCH assignment phase we should have seen T220_F not T200_S. Please anybody suggest on the same scenario.
i never dived so deep into those details, but it’s interesting. I would assume that the MS is trying to go on the TCH timeslot, after completed the SDCCH phase.
Therefore, it is possible that the MS is actually still logically located on the SDCCH (because it is not “really” on the TCH yet)
therefore, it uses T200_S.