Bug 2511

Summary:	HT Greenfield is not working
Product:	ns-3	Reporter:	Richard <epachamo>
Component:	wifi	Assignee:	sebastien.deronne
Status:	RESOLVED FIXED
Severity:	normal	CC:	epachamo, ns-bugs
Priority:	P5
Version:	unspecified
Hardware:	All
OS:	All
Attachments:	patch to fix and improve ht greenfield support

Description Richard 2016-09-27 20:52:45 UTC

Using 802.11n, Greenfield mode does not work.  Throughput drops to 0 bps.

I changed line 94 of the example:

https://www.nsnam.org/doxygen/ht-wifi-network_8cc.html

to read

phy.Set ("GreenfieldEnabled", BooleanValue(true));

as suggested in the tutorial file found at

https://www.nsnam.org/docs/models/html/wifi-user.html

Conducting further experiments in ad-hoc mode show it does not work in ad-hoc mode either.

I thought I might be doing something wrong and checked with the google groups community.

https://groups.google.com/forum/#!searchin/ns-3-users/greenfield%7Csort:relevance/ns-3-users/_kSMO2MRT4Y/M4dDJVilAgAJ

They suggested I contact the wifi-developer and let them know what was going on.

Comment 1 sebastien.deronne 2016-10-01 07:08:21 UTC

I will have a look, but reducing priority since GF mode is not really supported in practice (and has been removed with 802.11ac)

Comment 2 sebastien.deronne 2016-10-01 08:21:57 UTC

I could indeed reproduce the bug, I will work on a fix.

Comment 3 sebastien.deronne 2016-10-01 08:39:45 UTC

Greenfield is actually not supported, some pieces were already implemented (attributes, preamble readiness, ...) but not all is glued together yet to have it functional. I will take some time asap to see whether I can quickly come to something functional.

Comment 4 sebastien.deronne 2016-10-09 03:32:46 UTC

Created attachment 2607 [details]
patch to fix and improve ht greenfield support

This fixes the issues that were observed:
- HT Greenfield can only be used for HT PPDUs: missing conditions in MacLow
- InterferenceHelper had a missing condition for HT Greenfield
- Added some missing support in HT capabilities and HT operations for HT Greenfield format

Still missing come HT protection mechanisms but that can be tracked in another thread that I would like to take up asap.

Comment 5 Richard 2016-10-10 21:24:09 UTC

Wow, works well thanks for your help!

Comment 6 sebastien.deronne 2016-10-11 12:26:47 UTC

Thanks for your feedback, I suggest to push that fix.

Comment 7 sebastien.deronne 2016-10-14 08:53:47 UTC

Fixed in changeset 12369:0fdb8a2f4953