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Hello Jenkins Builder, pespin,
I'd like you to reexamine a change. Please visit
https://gerrit.osmocom.org/c/osmo-bts/+/41049?usp=email
to look at the new patch set (#2).
The following approvals got outdated and were removed:
Code-Review+1 by pespin, Verified+1 by Jenkins Builder
Change subject: FR/HR/EFR: implement SID filter in TCH UL path
......................................................................
FR/HR/EFR: implement SID filter in TCH UL path
As a result of how FR/HR/EFR DTX interacts with block diagonal
interleaving, at the beginning and end of each DTX pause a
correctly functioning TCH receiver will always pick up an
artifact consisting of 4 received bursts (2 for TCH/HS)
and same number of omitted bursts. Standard channel decoding
of this Rx artifact will produce a "half-block" in which half
of the bits prior to convolutional decoding will come from
a SID repetition whose Tx was notionally suppressed, while
the other half will be garbage. As a result of convolutional
decoding, the result will often appear as valid SID per
classification rules - but passing it as such to the Rx DTX
handler is wrong. Classic E1 BTS and GSM MS implementations
include a kind of SID filter at this point, setting BFI on
these received half-blocks, so that the Rx DTX handler will
see an invalid SID condition. Invalid SID means that comfort
noise generation is to be continued, but no updated CN
parameters are available - which is the truth in half-block
Rx situations. Implement the same filter.
Additional background info can be found here:
https://osmocom.org/projects/retro-gsm/wiki/DTXu_half-blocks
Change-Id: I46c62312316b04567bcadf6050597673f071247d
---
M include/osmo-bts/lchan.h
M src/common/l1sap.c
2 files changed, 58 insertions(+), 8 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/49/41049/2
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Gerrit-MessageType: newpatchset
Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: I46c62312316b04567bcadf6050597673f071247d
Gerrit-Change-Number: 41049
Gerrit-PatchSet: 2
Gerrit-Owner: falconia <fal...@freecalypso.org>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: pespin <pes...@sysmocom.de>
Gerrit-Attention: falconia <fal...@freecalypso.org>
Gerrit-Attention: pespin <pes...@sysmocom.de>
