QCA99XX with MU-MIMO and beamforming?

[Michal Kazior]

On 26 April 2016 at 16:35, Ben Greear <greearb at candelatech.com> wrote:
>
>
> On 04/25/2016 11:16 PM, Michal Kazior wrote:
>>
>> On 25 April 2016 at 22:31, Ben Greear <greearb at candelatech.com> wrote:
>>>
>>> Has anyone tried this?  Looks like hostapd has the ability to set the
>>> feature flags, but I am not sure if it is really working in ath10k?
>>
>>
>> Yes, it works. You need a few vht_capabs. I have mine like this:
>>
>>   >
>> vht_capab=[RXLDPC][SHORT-GI-80][TX-STBC-2BY1][SU-BEAMFORMER][SU-BEAMFORMEE][MU-BEAMFORMER][RX-ANTENNA-PATTERN][TX-ANTENNA-PATTERN][BF-ANTENNA-4][MAX-MPDU-11454][RX-STBC-1][MAX-A-MPDU-LEN-EXP7]
>>
>> The SU-, MU- and BF- are the required part only I think.
>>
>>
>>>
>>> Do you actually need anything other than standard whip antenna to
>>> allow this to function properly?
>>
>>
>> I don't think. FWIW Make sure the antennas are reasonably set
>> up/separated from each other. If you cram them too tight/randomly
>> beamforming won't work efficiently. I had problem with client antennas
>> being too close to each other and lying flat on a table (I than made a
>> foam-stand and put them a few cm apart) so the same thing must apply
>> to AP as well.
>>
>>
>>>
>>> What about station mode?
>>
>>
>> Works as well. Both on QCA99XX and QCA9377.
>
>
> Thanks for the info.  How did you determine that it actually worked?

Empirically. If you get 600mbps UDP to two 1x1 clients it works :)

Also, the rx bitrate on the receiving ath10k end will be kind of wierd
(there's currently no way to decode MU ratesets on Rx because group
ids are managed in firmware).


>
> My understanding is that the QCA99XX should be able to simultaneously
> transmit a 2x2 frame to one peer and another 2x2 frame to a second peer,
> but seems that would be hard to verify.

No, not really. MU- consumes 1 antenna, i.e. 4 antenna chip can do
split/MU- 3 spatial streams. This also implies you need at least 3
antenna chip for MU.


>
> Maybe just look for full-ish 2x2 throughput two two different 2x2 peers?

FWIW You can push 3 times 1x1 traffic which is, in theory, up to
roughly 900mbps. I was able to get up to 870mbps with ath10k w/ 3 UDP
1x1 clients on AP148.


>
> And, maybe there are some management frames to sniff for?

NDP advertisment I think although these are used for sounding and
don't imply MU encoding will be used.


> And finally, could you let me know the model number of your QCA9377 device?
> I'd like
> to get some for testing...

FWIW lspci tells me:

00:07.0 Network controller [0280]: Qualcomm Atheros Device [168c:0042] (rev 30)
        Subsystem: Qualcomm Atheros Device [168c:334f]

Do note the revision. I recall a different revision wasn't as good at
decoding MU as rev30, at least in my experience.


Michał