From: "Alwin Beukers" <alwin-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
To: "radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org"
<radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org>
Subject: RE: [RFC] VHT fields
Date: Fri, 15 Jun 2012 08:15:26 +0000 [thread overview]
Message-ID: <C6E8EE2D6B3ACB4582C1249E834B306505FEEE@SJEXCHMB13.corp.ad.broadcom.com> (raw)
> On Tue, 2012-06-12 at 15:05 +0000, Alwin Beukers wrote:
> > Hi everyone,
> >
> > This is a proposal for adding support for 802.11ac. Four fields were
> added to the suggested-fields section:
> >
> > http://www.radiotap.org/suggested-fields/SU_VHT
> > http://www.radiotap.org/suggested-fields/MU_VHT
> > http://www.radiotap.org/suggested-fields/GROUP_ID
> > http://www.radiotap.org/suggested-fields/PARTIAL_AID
> >
> > A Wireshark patch for parsing SU_VHT, GROUP_ID and PARTIAL_AID is
> attached.
>
> What's the reason for splitting it up?
Johannes,
The reason for splitting it up is to avoid extra overhead related to MU-MIMO
when describing VHT SU PPDUs. The separation is based on the different PLCP
header formats (VHT-SIG-A1/A2/B) for SU and MU PPDUs:
SU PPDUs:
- Only one NSTS, MCS and Coding field.
- Partial AID identifies recipient
- Group ID is always 0 (addressed to AP/mesh STA) or 63 (addressed to STA)
MU PPDUs:
- NSTS, MCS and Coding fields for up to four users
- Partial AID is not applicable
- Group ID is 1..62
All fields common to both SU and MU are in the SU_VHT field. The MU_VHT field
contains additional information for MU PPDUs. The GROUP_ID and PARTIAL_AID
fields have varying value or applicability.
So for SU PPDUs you would likely have SU_VHT and PARTIAL_AID fields, and maybe
a GROUP_ID field (for SU the GROUP_ID field only provides direction info that
could also be determined from PARTIAL_AID and/or MAC header).
For MU PPDUs you would have SU_VHT (for the common fields as well as
NSTS/MCS/Coding for the first user), MU_VHT (for NSTS/MCS/Coding for
additional users), and GROUP_ID.
By combining fields we can reduce complexity at the expense of some increased
overhead, what are your thoughts on his? Also, I was wondering if we need all
of the 'known' flags in SU_VHT. The MCS field (after which SU_VHT was modeled)
also has these, but I don’t know the rationale behind them. Can one assume a
driver has full access to the PLCP header and thus can fill in most of fields
in the SU_VHT field?
Thanks,
Alwin
> johannes
>
next reply other threads:[~2012-06-15 8:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-15 8:15 Alwin Beukers [this message]
[not found] ` <C6E8EE2D6B3ACB4582C1249E834B306505FEEE-HXj2mutaA2obnnZVN+9SiJr/X4hKkxxPpWgKQ6/u3Fg@public.gmane.org>
2012-06-15 8:29 ` [RFC] VHT fields Johannes Berg
2012-06-18 12:01 ` Johannes Berg
[not found] ` <1340020862.4615.8.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-06-19 10:56 ` Alwin Beukers
2012-06-18 18:32 ` Simon Barber
[not found] ` <4FDF7426.2050202-vp0mx6+5gkqFX2APIN6yfw@public.gmane.org>
2012-06-19 11:37 ` Alwin Beukers
-- strict thread matches above, loose matches on Subject: below --
2012-06-14 11:24 Alwin Beukers
2012-06-12 15:05 Alwin Beukers
[not found] ` <C6E8EE2D6B3ACB4582C1249E834B306505D68C-HXj2mutaA2obnnZVN+9SiJr/X4hKkxxPpWgKQ6/u3Fg@public.gmane.org>
2012-06-12 16:51 ` Johannes Berg
[not found] ` <1339519879.4531.13.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-06-13 10:42 ` Alwin Beukers
[not found] ` <C6E8EE2D6B3ACB4582C1249E834B306505E99C@SJEXCHMB13.corp.ad.broadcom.com>
[not found] ` <1339672828.4461.0.camel@jlt3.sipsolutions.net>
[not found] ` <1339672828.4461.0.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-06-14 12:05 ` Arend van Spriel
2012-07-04 17:18 ` Alwin Beukers
[not found] ` <C6E8EE2D6B3ACB4582C1249E834B306506E807-HXj2mutaA2obnnZVN+9SiJr/X4hKkxxPpWgKQ6/u3Fg@public.gmane.org>
2012-07-05 8:37 ` Johannes Berg
[not found] ` <1341477463.4455.17.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-07-23 13:43 ` Alwin Beukers
2012-07-05 9:08 ` Johannes Berg
[not found] ` <1341479327.4455.35.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-07-23 14:47 ` Alwin Beukers
[not found] ` <C6E8EE2D6B3ACB4582C1249E834B306508054B-HXj2mutaA2obnnZVN+9SiJr/X4hKkxxPpWgKQ6/u3Fg@public.gmane.org>
2012-07-23 15:25 ` Johannes Berg
[not found] ` <1343057111.4584.22.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-07-27 14:41 ` Alwin Beukers
[not found] ` <C6E8EE2D6B3ACB4582C1249E834B306508499C-HXj2mutaA2obnnZVN+9SiJr/X4hKkxxPpWgKQ6/u3Fg@public.gmane.org>
2012-08-20 16:42 ` Johannes Berg
[not found] ` <1345480938.4459.40.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-08-24 7:46 ` Alwin Beukers
[not found] ` <C6E8EE2D6B3ACB4582C1249E834B30650B4151-HXj2mutaA2obnnZVN+9SiJr/X4hKkxxPpWgKQ6/u3Fg@public.gmane.org>
2012-08-24 9:00 ` Johannes Berg
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