burst_ind and TCH

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Mad mad at auth.se
Tue Mar 15 17:02:09 UTC 2011


 Hi Sylvain, hi list!

 I'm experimenting with burst_ind and TCHs right now and ran
 into some problem I couldn't solve yet.

 After receiving an Assignment Command for a hopping TCH/F I
 call l1ctl_tx_dm_est_req_h1() with all necessary parameters
 and tch_mode GSM48_CMODE_SPEECH_V1 or _EFR.
 After that I do get burst indications containing the received
 bits on up- and downlink for the active arfcn on each
 consecutive frame number.

 BUT the rx level measurements are most of the time very low
 and sporadic higher, surely not from that nearby bts and the
 very close cellphone.
 It looks like the layer1 doesn't "hit" the right timeslot
 on the right arfcn at the right time.
 There are some possible sources of error leading to that, like
 hopping parameters, channel number and MA list.
 But I checked these and I took all of them directly from the
 ASS CMD, the MA as word list in ascending order, like in layer23
 IMM ASS handling.
 The specific AC doesn't have any specialties like Starting Time
 or "before time" parameters.

 So my question is if there is some obvious pitfall I'm missing
 and are there any suggestions how to debug that?


 Regards,
   Mad




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