Bug 2771

Created attachment 2897 [details]
Ideal Wifi patch

First patch is wrong, please ignore it and take this into account.

Could you please check against ns-3-dev?  IdealWifiManager was fixed (e.g. bug 2647) since the release of ns-3.26.

I have checked in ns-3-dev, the problem is still there. I still see ">" instead of ">=". After hg blame, I see that it was last changed in changeset 12686 but even before that ">" sign was used.

changeset 12686:
https://code.nsnam.org/index.cgi/ns-3-dev/rev/503f88506643

This is also the commit for bug 2647 but I do not think that they thought that as the NSS increases, the threshold should change. But since beamforming is not included yet, higher NSS can also have the same SNR threshold.

It looks ok, but I would like the approval of Matias and Tom before pushing this to the mainstream.

The patch is not against ns-3-dev; the code in ns-3-dev has changed in a way that I believe the problem is avoided.  It now says:

if (dataRate > bestRate && threshold < station->m_lastSnrObserved)

so if the nss yields a higher data rate, it should be selected.

Can you please check whether ns-3-dev exhibits a problem?

Hello Tom,

With the attached script that I have, I get the following ASSERT now:

msg="Reception ends in failure because of an unsupported number of spatial streams", file=../src/wifi/model/wifi-phy.cc, line=2399
terminate called without an active exception


Arguments to run the script with:

./waf --run 'scratch/vht_network_from_omer --nWifiAp=1 --nWifiSta=2 --udp=1 --ideal=2 --nssAp=3 --nssSta1=2 --nssSta2=1 --speed=0.0 --simulationTime=10.0 --fading=0 --distance=5'

Created attachment 2919 [details]
test script

Sorry, this was for 2771, for IdealWifiManager run it with

./waf --run 'scratch/vht_network_from_omer --nWifiAp=1 --nWifiSta=2 --udp=1 --ideal=1 --nssAp=3 --nssSta1=2 --nssSta2=1 --speed=0.0 --simulationTime=10.0 --fading=0 --distance=5'

and you get this error

against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs3 nss 1 GI 800 width 20
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs3 nss 1 GI 800 width 40
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs3 nss 1 GI 800 width 80
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs4 nss 1 GI 800 width 20
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs4 nss 1 GI 800 width 40
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs4 nss 1 GI 800 width 80
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs5 nss 1 GI 800 width 20
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs5 nss 1 GI 800 width 40
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs5 nss 1 GI 800 width 80
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs6 nss 1 GI 800 width 20
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs6 nss 1 GI 800 width 40
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs6 nss 1 GI 800 width 80
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs7 nss 1 GI 800 width 20
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs7 nss 1 GI 800 width 40
against TxVector VhtMcs0 nss 2 GI 800 width 80
Checking HtMcs7 nss 1 GI 800 width 80
against TxVector VhtMcs0 nss 2 GI 800 width 80
assert failed. cond="false", file=../src/wifi/model/ideal-wifi-manager.cc, line=192
terminate called without an active exception


Indicating that none of the txVector is within none of the thresholds in IdealWifiManager::GetSnrThreshold.

Created attachment 2922 [details]
proposed solution

Tom or Matias, I think I have a fix for this but I let you have a further investigation.

(In reply to sebastien.deronne from comment #9)
> Created attachment 2922 [details]
> proposed solution
> 
> Tom or Matias, I think I have a fix for this but I let you have a further
> investigation.

+1

Proposed patch works for a 3 antenna STA together with a 2 antenna STA without any problem.

Fixed in changeset 13080:804d4eccdc7f