Bug 2427 – 802.11ac selects wrong slot duration

Bug 2427 - 802.11ac selects wrong slot duration


Summary:	802.11ac selects wrong slot duration

Status:	RESOLVED FIXED

Product:	ns-3
Classification:	Unclassified
Component:	wifi
Version:	ns-3.25
Hardware:	All All

Importance:	P5 major
Assigned To:	sebastien.deronne

URL:
Keywords:

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2016-06-01 08:40 UTC by ad lee
Modified:	2016-06-10 16:12 UTC (History)
CC List:	2 users (show)

See Also:

Attachments
log, when NS_LOG=regularWifiMac=level_all. see line 182, slotset to 20000 back (24.13 KB, text/plain) 2016-06-01 08:40 UTC, ad lee	Details
patch to fix (757 bytes, patch) 2016-06-04 06:27 UTC, sebastien.deronne	Details \| Diff
patch to fix (701 bytes, patch) 2016-06-04 06:30 UTC, sebastien.deronne	Details \| Diff
Show Obsolete (1) Add an attachment (proposed patch, testcase, etc.)

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Description ad lee 2016-06-01 08:40:18 UTC

Created attachment 2458 [details]
log, when NS_LOG=regularWifiMac=level_all.  see line 182, slotset to 20000 back

when wifi.Install, the vht wifi's slot will be seted 9us.

but when sta associate with ap, ap consider sta as a none-erpSation(sta is a OfdmStation) , so ap wiil not set short slot, set ap-wifi-mac.cc line 759:

  m_stationManager->AddSupportedErpSlotTime (from, capabilities.IsShortSlotTime () && isErpStation);

then when ap Send Assoc Resp, sta recv it, and set slot 20us back~

It will lead to back off time wrong! e g .

Comment 1 sebastien.deronne 2016-06-03 14:15:54 UTC

If I understand well the description, 802.11ac selects a slot of 20 microseconds iso 9 microseconds at the moment it gets associated?

Comment 2 sebastien.deronne 2016-06-04 05:27:25 UTC

There is indeed an issue with 802.11ac and slot time selection when associating to an AP.

Comment 3 sebastien.deronne 2016-06-04 06:27:46 UTC

Created attachment 2459 [details]
patch to fix

m_erpSupported was badly set for 802.11ac.
Attached patch fixes the issue.

Comment 4 sebastien.deronne 2016-06-04 06:30:15 UTC

Created attachment 2460 [details]
patch to fix

Comment 5 ad lee 2016-06-07 03:53:08 UTC

I works, fix my problem . thx very much

Comment 6 sebastien.deronne 2016-06-07 12:30:45 UTC

Thanks for your feedback.
I suggest to deliver the fix.

Comment 7 Tom Henderson 2016-06-07 14:17:44 UTC

(In reply to sebastien.deronne from comment #6)
> Thanks for your feedback.
> I suggest to deliver the fix.

Agreed.

Comment 8 sebastien.deronne 2016-06-10 16:12:33 UTC

fixed in changeset 12152:0ca48e3ff8e7