Re: MCS field - STBC and Ness

[Simon Barber <simon-vp0mx6+5gkqFX2APIN6yfw@public.gmane.org>]

OK - I have now posted 3 patches on the proposal page (see Attachments):

1. A patch that applies to the Linux kernel v3.7-rc1 to collect the new 
STBC and Ness parameters from a wireless driver, and add them into the 
MCS radiotap field.
2. A patch to the Intel wireless driver in the kernel to collect STBC 
and Ness information.
3. A patch to wireshark to display STBC and Ness information.

With this I believe we have everything needed to start the 3 week 
comment period.

Simon


On 10/31/2012 05:22 PM, Simon Barber wrote:
> 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
>>