From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bifrost.lang.hm (lang.hm [66.167.227.134]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id C485C3B260 for ; Wed, 11 May 2016 19:25:35 -0400 (EDT) Received: from asgard.lang.hm (asgard.lang.hm [10.0.0.100]) by bifrost.lang.hm (8.13.4/8.13.4/Debian-3) with ESMTP id u4BNPMl0027671; Wed, 11 May 2016 16:25:22 -0700 Date: Wed, 11 May 2016 16:25:22 -0700 (PDT) From: David Lang X-X-Sender: dlang@asgard.lang.hm To: moeller0 cc: =?ISO-8859-15?Q?Toke_H=F8iland-J=F8rgensen?= , make-wifi-fast@lists.bufferbloat.net In-Reply-To: Message-ID: References: <871t58n5wk.fsf@toke.dk> <87zirwk4lw.fsf@toke.dk> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="680960-1571243673-1463009122=:10546" Subject: Re: [Make-wifi-fast] Thoughts on tackling airtime fairness 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: Wed, 11 May 2016 23:25:36 -0000 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --680960-1571243673-1463009122=:10546 Content-Type: TEXT/PLAIN; charset=utf-8; format=flowed Content-Transfer-Encoding: 8BIT On Wed, 11 May 2016, moeller0 wrote: >> On May 11, 2016, at 17:15 , Toke Høiland-Jørgensen wrote: >> >> David Lang writes: >>> >>> Take retransmissions as an example. They only happen because the >>> receiver didn't see them. If you were to get an aircap off the same >>> antenna as the receiver, you also wouldn't see them and therefor could >>> not account for them. In the real world, you are doing the aircap from >>> a different device, with a different antenna so what you see will be >>> even more different. Now think about the normal case where you have >>> two stations taking in two very different locations and one device to >>> do the aircap. >>> >>> If we don't have anything else, aircaps are what we have to fall back >>> on, but we need to realize how much we can't see at that point. >> >> Hmm, hadn't thought of that. Damn. Well, guess we'll have to trust the >> driver (or make it trustworthy if we can’t). > > This issue seems surmountable, just make sure the air-capping machine is a) located halfway between the other two hosts in question and b) has better antennas ;) . It should be possible to “degrade” the antenna quality of the two hosts to make sure the air-capper (sounds like a fancy whale species) has better RF visibility… better antennas on the aircap machine doesn't solve the problem for two reasons. 1. 'better' antennas are almost never better in every direction, they tend to change the pattern (for omnidirectional antennas, they trade vertical sensitivity for better horizontal sensitivity), so your 'better' antenna may not hear interference from the floor above you. 2. your 'better' antenna will pick up interference from stations further away which the receiving stations don't hear, so something they hear you may not be able to make out. There's a reason why RF engineering is half black magic and experience :-( David Lang --680960-1571243673-1463009122=:10546--