Re: Location Update (IMSI Attach) Procedure

Hey Osmoworld, Just a little intro before my rambling questions... I've been working on connecting OpenBTS and osmo-bts/OpenBSC together, and everything works well enough to at least send messages between the two (it's somewhat hackish but it works for me so far). The phone sees the network and when I attempt to connect, it is assigned a SDCCH and starts the typical location update process. This makes me think the underlying issue is in my OpenBSC/network setup. Now for the problems: (probably best to check the console output below first) Even though the MS receives an ID request and returns an ID response, the LU Request times out and returns cause=13 (default from config). I'm not sure what happens after the ID response since it doesn't seem to have sent anything else down to the MS. I also don't know too much about the MS's job, but it seems to send 3 LU requests every time (2 of which are unnecessary and rejected as duplicates). I assume that's what the preceding ERROR IND messages are referring to, but I don't know for certain. My BTS BCCH has LAI=001/01/1, which is correctly set in both OpenBTS and OpenBSC config files. The Location Updating Request contains LAI=001/01/65534, which I think may be the main issue since LAC=65534 is reserved (even looking in GSM-04.08, I couldn't find any details about this; can you shed some light please?). The MS works with standard OpenBTS by the way. I've looked through the gsm_04_08 code and Wireshark capture, but no clues stick out. I'm not too familiar with OpenBSC in general, so this could be as simple as setting some kind of config parameter. I figured I'd ask on here for help in case I'm just missing something basic. Here is the console output (with debug and authorize-everyone flags on): Wed Feb 22 13:06:24 2012 <0004> abis_rsl.c:1317 (bts=0,trx=0,ts=0,ss=0) Activating ARFCN(51) SS(0) lctype SDCCH r=LOCATION_UPDATE ra=0x0e ta=0 Wed Feb 22 13:06:24 2012 <0004> abis_rsl.c:1064 (bts=0,trx=0,ts=0,ss=0) CHANNEL ACTIVATE ACK Wed Feb 22 13:06:25 2012 <0000> abis_rsl.c:1493 (bts=0,trx=0,ts=0,ss=0) SAPI=0 ESTABLISH INDICATION Wed Feb 22 13:06:25 2012 <0002> gsm_04_08.c:1023 LOCATION UPDATING REQUEST: mi_type=0x01 MI(460020020292786) type=NORMAL Wed Feb 22 13:06:25 2012 <0001> gsm_04_08.c:114 (bts 0 trx 0 ts 0 pd 05) Sending 0x18 to MS. Wed Feb 22 13:06:25 2012 <0000> abis_rsl.c:1493 (bts=0,trx=0,ts=0,ss=0) SAPI=0 Wed Feb 22 13:06:25 2012 <0000> abis_rsl.c:1439 (bts=0,trx=0,ts=0,ss=0) ERROR INDICATION cause=unknown 0x0 Wed Feb 22 13:06:25 2012 <0000> abis_rsl.c:1493 (bts=0,trx=0,ts=0,ss=0) SAPI=0 ESTABLISH INDICATION Wed Feb 22 13:06:25 2012 <0002> gsm_04_08.c:1023 LOCATION UPDATING REQUEST: mi_type=0x01 MI(460020020292786) type=NORMAL ignoring request due an existing one: 0x20f1350. Wed Feb 22 13:06:25 2012 <0002> gsm_04_08.c:383 Subscriber 460020020292786: LOCATION UPDATING REJECT LAC=1 BTS=0 Wed Feb 22 13:06:25 2012 <0001> gsm_04_08.c:114 (bts 0 trx 0 ts 0 pd 05) Sending 0x04 to MS. Wed Feb 22 13:06:25 2012 <0000> abis_rsl.c:1493 (bts=0,trx=0,ts=0,ss=0) SAPI=0 Wed Feb 22 13:06:25 2012 <0000> abis_rsl.c:1439 (bts=0,trx=0,ts=0,ss=0) ERROR INDICATION cause=unknown 0x0 Wed Feb 22 13:06:25 2012 <0000> abis_rsl.c:1493 (bts=0,trx=0,ts=0,ss=0) SAPI=0 ESTABLISH INDICATION Wed Feb 22 13:06:25 2012 <0002> gsm_04_08.c:1023 LOCATION UPDATING REQUEST: mi_type=0x01 MI(460020020292786) type=NORMAL ignoring request due an existing one: 0x20f1350. Wed Feb 22 13:06:25 2012 <0002> gsm_04_08.c:383 Subscriber 460020020292786: LOCATION UPDATING REJECT LAC=1 BTS=0 Wed Feb 22 13:06:25 2012 <0001> gsm_04_08.c:114 (bts 0 trx 0 ts 0 pd 05) Sending 0x04 to MS. Wed Feb 22 13:06:25 2012 <0000> abis_rsl.c:1493 (bts=0,trx=0,ts=0,ss=0) SAPI=0 DATA INDICATION Wed Feb 22 13:06:25 2012 <0003> bsc_api.c:430 CLASSMARK CHANGE CM2(len=3) CM3(len=4) Wed Feb 22 13:06:27 2012 <0000> abis_rsl.c:1493 (bts=0,trx=0,ts=0,ss=0) SAPI=0 DATA INDICATION Wed Feb 22 13:06:27 2012 <0002> gsm_04_08.c:446 IDENTITY RESPONSE: mi_type=0x02 MI(357966009107140) Wed Feb 22 13:06:30 2012 <0002> gsm_04_08.c:484 Location Updating Request procedure timedout. Wed Feb 22 13:06:30 2012 <0002> gsm_04_08.c:383 Subscriber 460020020292786: LOCATION UPDATING REJECT LAC=1 BTS=0 Wed Feb 22 13:06:30 2012 <0001> gsm_04_08.c:114 (bts 0 trx 0 ts 0 pd 05) Sending 0x04 to MS. Wed Feb 22 13:06:30 2012 <0000> chan_alloc.c:429 (bts=0,trx=0,ts=0,ss=0) starting release sequence Wed Feb 22 13:06:30 2012 <0003> gsm_04_08_utils.c:231 Sending Channel Release: Chan: Number: 0 Type: 1 Wed Feb 22 13:06:30 2012 <0004> abis_rsl.c:579 (bts=0,trx=0,ts=0,ss=0) DEACTivate SACCH CMD Wed Feb 22 13:06:31 2012 <0000> abis_rsl.c:1493 (bts=0,trx=0,ts=0,ss=0) SAPI=0 RELEASE INDICATION Wed Feb 22 13:06:31 2012 <0004> abis_rsl.c:621 (bts=0,trx=0,ts=0,ss=0) RF Channel Release CMD due error 0 Wed Feb 22 13:06:31 2012 <0004> abis_rsl.c:658 (bts=0,trx=0,ts=0,ss=0) RF CHANNEL RELEASE ACK Thanks for any help, Tom Cooper -- Graduate Research Assistant Wireless @ Virginia Tech tacooper(a)vt.edu