Return-path: Received: from mail-wi0-f180.google.com ([209.85.212.180]:59103 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752462AbaJYTe6 (ORCPT ); Sat, 25 Oct 2014 15:34:58 -0400 Received: by mail-wi0-f180.google.com with SMTP id em10so3587088wid.1 for ; Sat, 25 Oct 2014 12:34:57 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <544AB9B8.9050407@mailservices.uwaterloo.ca> References: <544A7871.7020005@mailservices.uwaterloo.ca> <544AB9B8.9050407@mailservices.uwaterloo.ca> Date: Sat, 25 Oct 2014 08:19:28 -0700 Message-ID: (sfid-20141025_213501_232783_5045BFE1) Subject: Re: strange MPDU loss pattern From: Adrian Chadd To: Ali Abedi Cc: ath9k-devel , "linux-wireless@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 24 October 2014 13:42, Ali Abedi wrote: > We don't use a rate adaptation at this moment (i.e., fixed rate) and the > setup > is stationary. So we expect to see relatively stable channel conditions. > Even if the channel > conditions change during the aggregated frame. The first half of the MPDUs > have the same chance of experiencing worse channel conditions. How do you /know/ you have stable channel conditions? There are a lot of things that could be going on inside the devices you're testing on. It doesn't have to be channel noise coming in an antenna. For example, your computer could be generating rapidly changing noise spurs from some clocking sources. Try firing up the spectral scan mode on the NIC and plot the data. See if there are any abnormal peaks going on over time. And a large / long A-MPDU could be measured in milliseconds of length. the original poster didn't say which rate(s) they are trying with and how much margin (SNR) the receiver is seeing. Pulling out EVM from the received A-MPDU frames would also be helpful. Thanks, -adrian -adrian