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 <a2ab...@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

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