Bug 2315 – Problem when BACK Request is part of an A-MPDU

Bug 2315 - Problem when BACK Request is part of an A-MPDU


Summary:	Problem when BACK Request is part of an A-MPDU

Status:	RESOLVED FIXED

Product:	ns-3
Classification:	Unclassified
Component:	wifi
Version:	pre-release
Hardware:	All All

Importance:	P5 major
Assigned To:	sebastien.deronne

URL:
Keywords:

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2016-02-29 09:02 UTC by Matías Richart
Modified:	2016-03-01 14:43 UTC (History)
CC List:	1 user (show)

See Also:

Attachments
proposed fix to solve this bug (653 bytes, patch) 2016-02-29 15:20 UTC, sebastien.deronne	Details \| Diff
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Description Matías Richart 2016-02-29 09:02:41 UTC

When BACK Request is sent as part of an A-MPDU the, it is not count as a MPDU in ampdu tag. See ForwardDown in mac-low:
if (hdr->IsBlockAckReq ())
 {
   ampdutag.SetNoOfMpdus (queueSize - 1);
 }

However, when receiving the MPDUs in StartReceivePreambleAndHeader in yans-wifi-phy, it is not considered if it is a BACK request and m_mpdusNum is always decreased.

This makes the last MPDU to not be received correctly.

Comment 1 sebastien.deronne 2016-02-29 09:19:09 UTC

Matias, thanks for reporting, I will have a look.

Comment 2 sebastien.deronne 2016-02-29 15:20:10 UTC

Created attachment 2311 [details]
proposed fix to solve this bug

I agree, I do not see a reason for having size-1 when a BAR is piggybacked.
I checked back in the code and I do not think this change might hurt.
On the contrary, I suspect this bug is present for a while bug was only detected now (assert is triggered since proposed fix for bug 2313)

Comment 3 sebastien.deronne 2016-02-29 15:20:37 UTC

IMPORTANT fix, setting also to LAST CALL

Comment 4 Matías Richart 2016-03-01 06:20:41 UTC

The patch works for me.
I don't see any problems with the change.

Comment 5 sebastien.deronne 2016-03-01 14:43:49 UTC

pushed in changeset 11944:9d01f88b6c2c