VHT 160Mhz and nss related config.

[Sebastian Gottschall]

Am 12.02.2017 um 17:05 schrieb Ben Greear:
>
>
> On 02/12/2017 02:56 AM, Sebastian Gottschall wrote:
>> Am 11.02.2017 um 20:38 schrieb Ben Greear:
>>> On 02/11/2017 10:21 AM, Sebastian Gottschall wrote:
>>>> Am 11.02.2017 um 18:58 schrieb Ben Greear:
>>>>> On 02/10/2017 08:37 PM, Adrian Chadd wrote:
>>>>>> On 10 February 2017 at 20:22, Sebastian Gottschall
>>>>>> <s.gottschall at dd-wrt.com> wrote:
>>>>>>> i really can't believe this. if this is true the  160 mhz mode 
>>>>>>> would not
>>>>>>> make any sense.
>>>>>>> the maximum tx / rx rate for 4x4 vht80 and 2x2 vht160 is 
>>>>>>> identical. so
>>>>>>> vht160 would not increase performance in any way
>>>>>>
>>>>>> Well, if it can also do 2x2 MU-MIMO at 160MHz then it can be a
>>>>>> perfectly fine STA to a 4x4 160MHz MU-MIMO chip that can actually
>>>>>> transmit 2x2 rates to different MU-MIMO peers.
>>>>>>
>>>>>> That's the outstanding question I have - is it like, 2x2 MU only, or
>>>>>> is it say, 2 concurrently different spatial stream 2x2 MU? Ie, 
>>>>>> can you
>>>>>> have 2 peers, different VHT spatial groups (or 4 peers, 1 spatial
>>>>>> group each) all going at the same time?
>>>>>>
>>>>>> I'm .. not even sure how you're supposed to cleanly negotiate 
>>>>>> that you
>>>>>> can do 4NSS in VHT80 but 2NSS in VHT160 to a peer... that only makes
>>>>>> sense if you're doing lots of 1NSS and 2NSS MU-MIMO peers..
>>>>>
>>>>> I think using the max-rx-rate logic might could imply this, but I 
>>>>> am not sure
>>>>> many drivers fill this out properly.
>>>>>
>>>>> Looks like a mess waiting to happen to me.
>>>>>
>>>>> Even if you can do 1x1 160Mhz MU-MIMO to two stations, and I am 
>>>>> not certain you
>>>>> can since in 80Mhz you can only do a 1x1 and a 2x2 (not two 2x2).
>>>>>
>>>>> So, from what I know currently, 80+80 is not that useful on the 
>>>>> 9984 NIC...
>>>> never tried 80+80 since i need to enhance the channel logic alot in 
>>>> my firmware code to handle it. would be great enough if vht160 
>>>> would work as expected and
>>>> i'm not sure right now if it really works, even if the interface 
>>>> initialized correctly it assocs only with vht80
>>>
>>> 160Mhz is really implemented as 80+80 internally it seems, so what I 
>>> meant is that
>>> 160Mhz or 80+80 both have the 2x2 restriction.
>> since i have a older fw source. can you give me a hint where you 
>> found a indication that its just 2x2?
>
> Look for:
>
> MAX_SPATIAL_STREAMS_SUPPORTED_AT_160MHZ
your findings where correct. frustrating.
>
> Thanks,
> Ben
>


-- 
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Sebastian Gottschall / CTO

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