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Bug #3630

Too restrictive channel combination checks for nanoBTS

Added by roox about 1 month ago. Updated about 1 month ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
ip.access BTS
Target version:
-
Start date:
10/06/2018
Due date:
% Done:

0%

Spec Reference:
Tags:

Description

Today i've played with new cell broadcast support.
While it worked out of the box with osmo-bts and osmo-trx-lms I had some issues with a nanoBTS.

nanoBTS-GSM-Datasheet-v1.0.pdf states that it should be a possible to configure a CBCH on TS0 or TS1.

CCCH+SDCCH4+CBCH on TS0 fails with:

  <0004> abis_nm.c:1893 OC=CHANNEL(03) INST=(00,00,00): Invalid Channel Combination 7 on (bts=0,trx=0,ts=0). Reason: TS0 of TRX0 must carry a BCCH.

CCCH on TS0 + SDCCH8+CBCH on TS1 seems to work but it feels somewhat unreliable.
While a Samsung Galaxy A3 (2016 - SMA310F) seem to work fine a good old Nokia 6300 (RM-217) has issues getting onto the network:

<0003> abis_rsl.c:1359 (bts=0) CHAN RQD: reason: Location updating (ra=0x08, neci=0x01, chreq_reason=0x03)
<0010> lchan_fsm.c:76 lchan(0-0-1-SDCCH8_CBCH-1)[0x55736648f310]{WAIT_RLL_RTP_ESTABLISH}: (type=SDCCH) lchan allocation failed in state WAIT_RLL_RTP_ESTABLISH: Timeout
<0010> lchan_fsm.c:99 lchan(0-0-1-SDCCH8_CBCH-1)[0x55736648f310]{WAIT_RLL_RTP_ESTABLISH}: (type=SDCCH) Tx Immediate Assignment Reject (lchan allocation failed in state WAIT_RLL_RTP_ESTABLISH: Timeout)
<0010> lchan_fsm.c:76 lchan(0-0-1-SDCCH8_CBCH-3)[0x55736648f7b0]{WAIT_RLL_RTP_ESTABLISH}: (type=SDCCH) lchan allocation failed in state WAIT_RLL_RTP_ESTABLISH: Timeout
<0010> lchan_fsm.c:99 lchan(0-0-1-SDCCH8_CBCH-3)[0x55736648f7b0]{WAIT_RLL_RTP_ESTABLISH}: (type=SDCCH) Tx Immediate Assignment Reject (lchan allocation failed in state WAIT_RLL_RTP_ESTABLISH: Timeout)

Disabling the cannel config checks in src/osmo-bsc/abis_nm.c finally let me use CCCH+SDCCH4+CBCH on TS0 on the nanoBTS.
This also seems to work without any issues so far.

History

#1 Updated by laforge about 1 month ago

please try https://gerrit.osmocom.org/#/c/osmo-bsc/+/11257 and report if it solves
the problem.

#2 Updated by roox about 1 month ago

laforge wrote:

please try https://gerrit.osmocom.org/#/c/osmo-bsc/+/11257 and report if it solves
the problem.

CCCH+SDCCH4+CBCH can now be configured on TS0.
Thanks for the fix.

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