Project

General

Profile

Bug #1801

AMR DTX: downlink logic flawed

Added by laforge almost 2 years ago. Updated over 1 year ago.

Status:
Closed
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
08/20/2016
Due date:
% Done:

100%

Estimated time:
Spec Reference:

Description

The AMR DTX logic operates as follows:
  • if there is an incoming downlink RTP frame in the queue for this lchan, send it
  • else, generate PH-EMPTY-FRAME.req or PH-DATA.req with SID payload, depending on time (also broken, see #1799)

This is flawed, as it assumes that the incoming RTP stream is always well-formed and -timed. It would for example also mean that a RTP stream with lots of extra SID frames (more than every 160ms) would result in all of those SID frames transmitted over the radio interface, where the spec says we should only transmit one SID_UPDATE every 160ms.

To quote a rule from IETF: we should be conservative in what we send and tolerant in what we receive.


Related issues

Related to OsmoBTS - Bug #1799: AMR DTX: last_sid should operate on codec frame intervals (20ms), not gsm frame numberClosed2016-08-20

Related to OsmoBTS - Bug #1800: AMR DTX: lchan->tch.last_sid is never populated with save_last_sid()Closed2016-08-20

Related to OsmoBTS - Bug #1803: osmo-bts-litecell15: AMR FR: some RTP buffers are never releasedClosed2016-08-20

Related to OsmoBTS - Bug #1802: AMR DTX Downlink: We are not sending ONSET ?!?Closed2016-08-20

Related to OsmoBTS - Bug #1892: AMR half rate crashes osmo-btsClosed2016-12-20

History

#1 Updated by laforge almost 2 years ago

  • Description updated (diff)

#2 Updated by laforge almost 2 years ago

  • Related to Bug #1799: AMR DTX: last_sid should operate on codec frame intervals (20ms), not gsm frame number added

#3 Updated by laforge almost 2 years ago

  • Related to Bug #1800: AMR DTX: lchan->tch.last_sid is never populated with save_last_sid() added

#4 Updated by laforge almost 2 years ago

#5 Updated by laforge almost 2 years ago

  • Related to Bug #1803: osmo-bts-litecell15: AMR FR: some RTP buffers are never released added

#6 Updated by laforge almost 2 years ago

  • Assignee changed from sysmocom to msuraev

#7 Updated by msuraev almost 2 years ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 20

Fix available as gerrit #858.

#8 Updated by msuraev almost 2 years ago

  • % Done changed from 20 to 80

Should be fixed by gerrit # 1029 and corresponding fixes from related bugs.

#9 Updated by msuraev almost 2 years ago

  • Related to Bug #1802: AMR DTX Downlink: We are not sending ONSET ?!? added

#10 Updated by msuraev almost 2 years ago

  • File dtx.dot added

Not sure what's the right place for .dot file so attaching current version here for the time being.

#11 Updated by msuraev over 1 year ago

AMR FR is working fine with #rtp jitter-buffer 0'.

#12 Updated by ylebel over 1 year ago

Je serai absent pour la période du 19 décembre 2016 au 3 février 2017 inclusivement. Pour toute question, contactez M. David Bourget à l'adresse . ************************************************* I'll be out of the office from December 19th 2016 to February 3rd 2017 inclusively. If you need immediate assistance, please contact Mr David Bourget at .

#13 Updated by msuraev over 1 year ago

Remaining AMR HR issues:
- FACCH insertion: proper use of SID_FIRST_INH (if SID_FIRST_P1 was used before FACCH) and SID_UPDATE_INH (if SID_UPDATE was used before FACCH)
- SID_UPDATE_INH is not sent to L1 in downlink
- SID_FIRST_INH is not sent to L1 in downlink
- Undesired speech frame during DTX seems to mess up the FSM. SID_UPDATE becomes SID_FIRST_P1

Note: this has not been re-tested with latest master yet.

#14 Updated by msuraev over 1 year ago

  • Related to Bug #1892: AMR half rate crashes osmo-bts added

#15 Updated by msuraev over 1 year ago

  • File deleted (dtx.dot)

#16 Updated by msuraev over 1 year ago

gerrit# 1508 should fix AMR HR problem with inhibition by voice frames. FACCH for AMR HR is WIP.

#17 Updated by msuraev over 1 year ago

Gerrit # 1611 should fix the issue with FACCH for AMR HR.

#18 Updated by msuraev over 1 year ago

  • Status changed from In Progress to Stalled

#19 Updated by msuraev over 1 year ago

  • Status changed from Stalled to Resolved
  • % Done changed from 80 to 100

All fixes has been merged, docs update will follow up shortly.

#20 Updated by laforge over 1 year ago

  • Status changed from Resolved to Closed

Also available in: Atom PDF

Add picture from clipboard (Maximum size: 48.8 MB)