Bug 2427

Summary: 802.11ac selects wrong slot duration
Product: ns-3 Reporter: ad lee <adonislixi>
Component: wifiAssignee: sebastien.deronne
Status: RESOLVED FIXED    
Severity: major CC: ns-bugs, tomh
Priority: P5    
Version: ns-3.25   
Hardware: All   
OS: All   
Attachments: log, when NS_LOG=regularWifiMac=level_all. see line 182, slotset to 20000 back
patch to fix
patch to fix

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