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Bug #3233

closed

Extremely slow FACCH processing

Added by laforge almost 6 years ago. Updated over 5 years ago.

Status:
Resolved
Priority:
High
Assignee:
-
Category:
osmo-bts-trx
Target version:
Start date:
05/04/2018
Due date:
% Done:

100%

Spec Reference:

Description

While developing the RLL tests for BTS_Tests.ttcn, I am having trouble of sending uplink FACCH frames via trxcon.

However, I'm having problems finding any code that actually relates to it. So I'm a bit at a loos how FACCH transmission is supposed to work in trxcon?

It seems like if a TCH is activated, trxcon assumes that all bursts/blocks are voice, which is wrong.

Some general rules about FACCH handling:
  • the network side can at any time schedule a FACCH instead of voice bursts
  • the MS can at any time send a FACCH (via L1CTL_DATA_REQ), which will always pre-empt (and drop!) a voice (L1CTL_TRAFFIC_REQ) at the same time. It's exactly the same in osmo-bts in the downlink. FACCH always has higher priority than voice, an a voice frame needs to be dropped whenever FACCH is transmitted.

Also, as long as the channel mode is SIGNALLING, no voice frames are ever transmitted, but basically all bursts are part of FACCH. Only once the GSM48_CMODE_SIGN is switched to GSM48_CMODE_SPEECH_*, we are permitted to send codec frames in uplink.


Files

20180504-TC_rll_est_ind-FACCH.pcapng 20180504-TC_rll_est_ind-FACCH.pcapng 22.6 KB pcap file (GSMTAP + RSL) of non-working FACCH case laforge, 05/04/2018 02:28 PM
20180504-TC_rll_est_ind-SDCCH.pcapng 20180504-TC_rll_est_ind-SDCCH.pcapng 27.5 KB pcap file (GSMTAP + RSL) of working SDCCH case laforge, 05/04/2018 02:28 PM
TC_rll_est_ind-FACCH.log TC_rll_est_ind-FACCH.log 5.76 MB titan log file of non-working FACCH case laforge, 05/04/2018 02:28 PM
TC_rll_est_ind-SDCCH.log TC_rll_est_ind-SDCCH.log 1.7 MB titan log file of working SDCCH case laforge, 05/04/2018 02:29 PM
facch_delay.pcapng.gz facch_delay.pcapng.gz 21.8 KB fixeria, 05/06/2018 07:48 PM
disable_clock_reset.patch disable_clock_reset.patch 444 Bytes fixeria, 05/06/2018 07:49 PM
facch_looong.pcapng.gz facch_looong.pcapng.gz 1.46 KB fixeria, 06/25/2018 02:46 PM
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