[ath9k-devel] strange MPDU loss pattern

[Ali Abedi <a2abedi@uwaterloo.ca>]

The paper mentioned that this happens when the client is mobile.
But I confirm Adrian's observation . This problem happens even
in stationary environments with dynamic channels (e.g., people moving in 
the vicinity
of the AP/Client).


Best,
Ali


On 14-10-30 12:11 PM, Adrian Chadd wrote:
> On 30 October 2014 08:48, Ali Abedi <a2abedi@uwaterloo.ca> wrote:
>> Hi Adrian,
>>
>>
>> We observed that this can happen for any rate for some SNR values.
>> If the SNR is strong enough for the given MCS this won't happen.
>> But when the SNR approaches the transition region when
>> error rate starts to increase, this problem will be observed.
>>
>> So this can happen even for MCS0->MCS4 when the client is far from the AP
>> and specially when it's moving.
> Right. That's the missing useful information here. :)
>
> Yes, I'd expect this happens whilst the client is moving. The training
> stuff is all done on the beginning of the packet and channel
> conditions aren't adjusted during packet reception - only upon the
> next received packet.
>
> (FYI - I've seen a similar pattern, but when i stand between the AP /
> STA at > MCS13 and start waving my hands around. Just that slight
> change in channel conditions == the above failure.)
>
> So thanks for reminding us that we should take A-MPDU length into
> account in our rate control code. :)
>
>
>
> -adrian