GPRS on osmo-trx not working

historical

Hi Neels,

On Tue, Jun 28, 2016 at 8:45 AM, Neels Hofmeyr <nhofmeyr at sysmocom.de> wrote:
> Voice is working well, but I can't seem to get GPRS working on osmo-trx.

Generally this is strange behavior because there no difference between
GPRS and non-GPRS bursts at the osmo-trx level.

> I also tried to use a PCU from before EDGE support was merged, so that's
> not causing it.
>
> Any ideas on what might be causing this?
> With sysmobts, for example, I needed to configure the pcu with
> --enable-sysmocom-dsp. Any such things with osmo-trx?

I'm using the latest PCU version 189742b6 with reverted commit
"f1a7b8f tbf: Add state WAIT_ASSIGN". I did pass any build time
arguments.

> Some of the log messages look quite bad, like
> 20160628170840743 DNS <0010> gprs_ns.c:951 NS RESET ACK Discarding unexpected message for NS-VCI 1800 from SGSN NSEI=1800
>
> I didn't do the rts-advance increase by 5, because when that log message is
> issued, the PCU is not running yet:
> 20160628170837632 DL1C <0006> scheduler.c:240 Prim for trx=0 ts=0 at fn=272652 is out of range, or channel already disabled. If this happens in conjunction with PCU, increase 'rts-advance' by 5. (current fn=272658)

I have not encountered this error and have not modified 'rts-advance'.
My general concern is packet loss at the RF level, but this error
looks like it may be more related to initialization and O&M.

> NOTICE 140232141276928 17:27:18.0 Transceiver.cpp:241:start: Starting the transceiver
> NOTICE 140232141244160 17:27:18.5 Transceiver.cpp:380:pushRadioVector: dumping STALE burst in TRX->USRP interface
> ^ I see ~130 of these notices of a stale burst, but all with an identical timestamp, and only
>   once after osmo-bts-trx starts up.

You may see these messages at startup as the transport syncs, which is
not a concern.

I will try testing with you're log files. The rxgain at 1 in
osmo-bts.cfg is definitely low. I'm using a setting of 25 with a
VERT900 antenna at roughly a 5 meter test distance.

  -TT