From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Barber Subject: Re: MCS field - STBC and Ness Date: Wed, 31 Oct 2012 17:22:20 -0700 Message-ID: <5091C0BC.4040305@superduper.net> References: <4FAC5DE0.90708@superduper.net> <4FACBA13.9040509@neratec.com> <4FAD41E4.3090803@superduper.net> <4FAD43F0.20807@superduper.net> <1336761346.8739.3.camel@jlt3.sipsolutions.net> <4FADE69F.9040100@superduper.net> <1341479550.4455.36.camel@jlt3.sipsolutions.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1341479550.4455.36.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org> Sender: radiotap-owner-sUITvd46vNxg9hUCZPvPmw@public.gmane.org To: Johannes Berg Cc: Wojciech Dubowik , radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org List-Id: radiotap@radiotap.org Hi Johannes & Wojciech, My work has been on hold, but has recently come off hold. I'm getting the patches together. As I rebase my work onto the current wireshark trunk I've found a simpler implementation of STBC has been applied by Wojciech. My proposal extends the STBC from his implemented 1 bit to the full 2 bits allowed in the 11n specification, and also includes 2 bits of Ness. I've posted an ieee80211 patch, and an intel driver patch (both attached to the proposed radiotap extension page). l'll post a wireshark patch shortly to start the comment period. Simon On Thu 05 Jul 2012 02:12:30 AM PDT, Johannes Berg wrote: > On Fri, 2012-05-11 at 21:27 -0700, Simon Barber wrote: >> Another slight tweak - I think STBC is more commonly used than Ness (as >> witnessed by Wojciech's interest), so give STBC the simpler encoding. I >> believe Ness is used for beamforming soundings. >> >> Spec would look like this: >> >> known definition >> 0x01 bandwidth >> 0x02 MCS index known (in mcs part of the field) >> 0x04 guard interval >> 0x08 HT format >> 0x10 FEC type >> 0x20 STBC >> 0x40 Ness - Number of extension spatial streams is known >> 0x80 Ness2 - bit 1 (MSB) of Number of extension spatial streams. >> >> The flags field is any combination of the following: >> >> flag definition >> 0x03 bandwidth - 0: 20, 1: 40, 2: 20L, 3: 20U >> 0x04 guard interval - 0: long GI, 1: short GI >> 0x08 HT format - 0: mixed, 1: greenfield >> 0x10 FEC type - 0: BCC, 1: LDPC >> 0x60 STBC - 0, 1 or 2: number of STBC streams >> 0x80 Ness - bit 0 (LSB) of Number of extension spatial streams. >> >> What should I do to advance this as an approved radiotap extension? > > I suppose you already have patches for wireshark for this? I can help > you out with a patch for the Linux kernel as an example producer of > this, and then I think just repost it to the list again to leave some > more discussion time. > > johannes >