HAR2009 TODO: USe both TRX with BS-11

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Harald Welte laforge at gnumonks.org
Tue Aug 4 08:13:48 UTC 2009


On Thu, Jul 23, 2009 at 12:26:14AM +0200, Harald Welte wrote:

> * test dual-TRX operation of BS-11 on OpenBSC [Stefan/Daniel, can you do that?]

Since I didn't proceed much on the Multidrop issue yesterday, I spent
a bit of time investigating this.  I have fixed two minor bugs in bsc_hack
regarding the setup of TRX1, but now both TRX become live.

I've also twisted the channel allocator to first use+exhaust TRX1 before going
to TRX0 timeslots.  What's weird is that the first allocated channel (TRX1/TS0)
is not useable, with the following behaviour:

* we see a channel request on the RACH
* we assign TRX1/TS0  on the AGCH
* we activate the channel on the BTS
* we see the CM Service request from the MS on the TRX1/TS0
* we send the CM Service Ack from the BTS to the MS on TRX1/TS0
* after some time, T200 of the Um interface expires and the phone gives up.

So it seems the CM Service ACK is never received by the phone.

I have verified the TRX1/TS0 channel configuration is TCH/Full in LMT
I have verified the CM Service ACK is transmitted to the correct GSM channel
by usign the MA-10 protocol analyzer.

This is really weird.

For Timeslot 1 and higher, everything is working fine.

I've reviewed the relevant code sections, and there is no special treetment
of TS0 on any TRX that is != C0. (trx0).

Any ideas?

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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