multiple phy with osmo-trx

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Max msuraev at sysmocom.de
Wed Aug 10 14:17:09 UTC 2016


Ok, with

sudo chrt 15 ./src/osmo-bts-trx/osmo-bts-trx -t 2 -c
~/.config/osmocom/osmo-bts-mtrx.cfg -d DRTP:DCC:DRSL:DL1C

it starts but phone fails to see the network - openbsc gives following
error:

<0004> bsc_init.c:287 bootstrapping RSL for BTS/TRX (0/0) on ARFCN 878
using MCC=1 MNC=64 LAC=1 CID=0 BSIC=63
<001d> input/ipa.c:265 accept()ed new link from 192.168.122.1 to port 3003
<0004> bsc_init.c:287 bootstrapping RSL for BTS/TRX (0/1) on ARFCN 880
using MCC=1 MNC=64 LAC=1 CID=0 BSIC=63
<0000> abis_rsl.c:1835 (bts=0,trx=1,ts=0,ss=0) ERROR INDICATION
cause=SABM frame with information not allowed in this state in state=ACTIVE
<0002> gsm_04_08.c:472 Subscriber 1640000005666: LOCATION UPDATING
REJECT LAC=1 BTS=0
<0002> gsm_subscriber.c:309 Subscriber 1640000005666 ATTACHED LAC=1
<001d> input/ipaccess.c:277 Bad signalling message,sign_link returned error
<001d> input/ipaccess.c:277 Bad signalling message,sign_link returned error
<0000> abis_rsl.c:1835 (bts=0,trx=1,ts=0,ss=0) ERROR INDICATION
cause=Timer T200 expired (N200+1) times in state=RELEASE REQUESTED

Could you share which versions/branches have you used in your tests?

Also could elaborate on '-m' - what's this option for and when it's
necessary? How it's support to affect osmo-bts configuration?


On 08/02/2016 12:39 AM, Tom Tsou wrote:
> Hi Max,
>
> On Mon, Aug 1, 2016 at 7:57 AM, Max <msuraev at sysmocom.de> wrote:
>> I've asked about it before but this seems to have been lost in
>> communication.
> I do not recall this discussion. My apologies.
>
>> The question is basically how to enable multi-TRX support for
>> osmo-bts-trx using phy/instance infrastructure similar to other bts?
> I use the following configuration.
>
> phy 0
>  instance 0
>  instance 1
>  osmotrx rx-gain 25
>
> bts 0
>  band 900
>  ipa unit-id 1234 0
>  oml remote-ip 127.0.0.1
>  settsc
>  gsmtap-sapi ccch
>  gsmtap-sapi pdtch
>  trx 0
>   phy 0 instance 0
>  trx 1
>   phy 0 instance 1
>
> $ osmo-bts-trx -c osmo-bts.cfg -t 2
>
>> In short, I'd like to configure OpenBSC with 1 BTS with 2 TRX, each with
>> its own arfcn and set of channels. I'm running "osmo-bts-trx -t 2" and
>> correspondingly "osmo-trx -c 2" on usrp b210. Any ideas on what's
>> missing to make this actually work are greatly appreciated.
> You can use "osmo-trx -c 2" or "osmo-trx -m -c 2" to use dual-channels
> of the B210 or multi-ARFCN on one channel respectively.
>
> Note that there are ARFCN restrictions for both cases. Due to a shared
> local oscillator for both B210 channels, ARFCN separation can be up
> about 25 MHz.
>
> With multi-TRX, ARFCN spacing is fixed at 800 kHz or 4 GSM channels.
> So if TRX-0 is set to ARFCN 51, TRX-1 _must_ be set to 55. Up to three
> ARFCN's is supported for multi-TRX.
>
>   -TT

-- 
Max Suraev <msuraev at sysmocom.de> http://www.sysmocom.de/
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