From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp86.iad3a.emailsrvr.com (smtp86.iad3a.emailsrvr.com [173.203.187.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 40FD43B2A2 for ; Thu, 15 Dec 2016 08:40:55 -0500 (EST) Received: from smtp35.relay.iad3a.emailsrvr.com (localhost [127.0.0.1]) by smtp35.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 0B9385B0B; Thu, 15 Dec 2016 08:40:55 -0500 (EST) Received: from app17.wa-webapps.iad3a (relay-webapps.rsapps.net [172.27.255.140]) by smtp35.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id F1D735C17; Thu, 15 Dec 2016 08:40:54 -0500 (EST) X-Sender-Id: MAILER-DAEMON Received: from app17.wa-webapps.iad3a (relay-webapps.rsapps.net [172.27.255.140]) by 0.0.0.0:25 (trex/5.7.12); Thu, 15 Dec 2016 08:40:55 -0500 Received: from reed.com (localhost [127.0.0.1]) by app17.wa-webapps.iad3a (Postfix) with ESMTP id E2E136003A; Thu, 15 Dec 2016 08:40:54 -0500 (EST) Received: by mobile.rackspace.com (Authenticated sender: dpreed@reed.com, from: dpreed@reed.com) with HTTP; Thu, 15 Dec 2016 08:40:54 -0500 (EST) Date: Thu, 15 Dec 2016 08:40:54 -0500 (EST) From: dpreed@reed.com To: "Dave Taht" Cc: make-wifi-fast@lists.bufferbloat.net MIME-Version: 1.0 Content-Type: text/plain;charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Message-ID: <1481809254.926712488@mobile.rackspace.com> X-Mailer: mobile/4.0.0 Subject: Re: [Make-wifi-fast] =?iso-8859-1?q?half_the_transmission_time=3F?= X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Dec 2016 13:40:55 -0000 The citation for the "fact" in the first paragraph is a theory paper, not a= measurement paper. My experience with theory papers in this space is that they are incredibly = sensitive to assumptions, and such assumptions are often wildly wrong compa= red to the real world of radio, often in the pessimistic direction! Theorists are terrible at inventing models unless their models are tested b= y measuring. Thus, it is important for the measurement community to adopt the attitude o= f experimental physics... Measure all predicted behaviors, even if you'd li= ke to believe the beautiful theory. This is how the diameter of the proton = was discovered to be off in the second significant digit, way off. Yet we a= re repeatedly told by the theoretical physicists that the Standard Model is= accurate to 15 significant digits at minimum. Theory is great, and I use it a lot, even doing my own theory work. But I a= lso check predictions about engineered systems by measuring. Even such clai= ms as "widely known facts", which, by the way should been challenged by pee= r review! Do we know any measurements that challenge this claim? Of course...=20 -----Original Message----- From: "Dave Taht" Sent: Wed, Dec 14, 2016 at 6:55 pm To: make-wifi-fast@lists.bufferbloat.net Subject: [Make-wifi-fast] half the transmission time? H/T to Bruno Moraes: "Over half of the transmission time in WiFi networks is dedicated to ensuring that errors are corrected or detected. Despite these mechanisms, many studies have concluded that frame error rates vary. An increased understanding of why frames are lost is a pragmatic approach to improving real world 802.11 throughput. The potential beneficiaries of this research, include rate control algorithms, Modulation and Coding Schemes, simulation models, frame size selection and 802.11 configuration guidelines. This paper presents a measurement study of the factors which correlate with packet loss in 802.11 WiFi. Both passive and active approaches were used to investigate how the frame size, modulation and coding scheme and airtime effect the loss rate. Overall, packet errors were high, but the size of frames were not a major determinant of the loss rate. The loss rate decreased with the airtime but at substantially lower rates than those suggested in simple packet error models. Future work will further try to isolate and investigate specific errors, such as head on collisions in the preamble" --=20 Dave T=C3=A4ht Let's go make home routers and wifi faster! With better software! http://blog.cerowrt.org _______________________________________________ Make-wifi-fast mailing list Make-wifi-fast@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/make-wifi-fast