From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 3E2883B260 for ; Thu, 12 May 2016 02:41:28 -0400 (EDT) Received: from [172.17.3.79] ([134.76.241.253]) by mail.gmx.com (mrgmx001) with ESMTPSA (Nemesis) id 0MDymt-1apSa623sl-00HLrm; Thu, 12 May 2016 08:41:13 +0200 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) From: moeller0 In-Reply-To: Date: Thu, 12 May 2016 08:41:09 +0200 Cc: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , make-wifi-fast@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <295C11EF-4A88-4BB8-B489-779B317FA433@gmx.de> References: <871t58n5wk.fsf@toke.dk> <87zirwk4lw.fsf@toke.dk> To: David Lang X-Mailer: Apple Mail (2.2104) X-Provags-ID: V03:K0:SGStvplXhq1p4m9HiKUMxq9XyRqfMtzymDw/c0qb8oa2EaRINk6 2AYWk7j0GriI9eciTNBiNo3ZkksZXIS7Y/SD5eHGurCW/iD80SJt5hxzjSZBl0Gggbp0vCb eGVLAe8qpnbBf2iGXGp/Jw1wptf0WlQB1T0Ur7oB1H0KX9T9xsGnHPalTVFbyc8d0ez7q76 w9UqKSu3NH5vNs5t4Km5g== X-UI-Out-Filterresults: notjunk:1;V01:K0:30pxLJiTVbE=:DnWMpLvOEjZUqN7qtw6itR piNj3Ayi69leDEJCoCkAGUJHD5h7EDvwEkKZ5gXWDluLXQwSKJoK/ijN8rPGWZ3ZrAojwd67g HCkRhwiVruECPRVChyj3b9JaT5iYqHo4ifV+c8mhiTGGUbDbYxqtbgdqyzHm96klNR+0wa5LR 5RO4oAP9jlXKx8bKMsbQcz05HrBkRIlsNBso4pPuGiL7KWB192308eVsW7mQkmVZzfPM3Ll5k KsIFGH3R+Wz+cO1z0mGR6utqFN2B/F+nZgHaEWfRFuHXi0ng2VX7XxNw75wc7NtBJYKPbLrBc r2YBqV5ynHhc4kgKbzrq1weaTuVXBwV5tr6c2ql6Qf7Cvf6DrejQsMYjZN8vriV1d2CU2rIWv 2Xxlps4t8H+Uz3tPWYOF4ynvl7QDlGmguP9PCW0oSxaTJCPISsHDAleqxZIsJCWPfDuvuuJeZ 8mouOQoTq8LYTIwJHFZj2B1LIMW6yrqFqXyxfq4SKUfUS/vQDQK7b+2eo7Up+NM7jyqL0EBST 33rh7kTMq9KasKTRm/HrCnHd+PsKHN+4QKLld+q1f2MU12XPeHfJiT43+SHlJnCCrCEp9xHH7 Wm96ONlwCisR3ElSm37ftNa40phTvS4MK6VnavLLsgXcm6MHeTQTvGwyWR3ptR/RBs6Cs5FyO pAaKCMuKVEAVaNfh960ULuXAQQ2zNu+SYLOoxwuAWGlEse+3GfYqF8x+6W51gjKqptrSb8YNW 6KObfqaoF0nrSxkSu2tpnFMyFJQLFJYPchus85tlQcV22KyCeHBRXqVS9/tuSmumnSCLGZ7H9 654F7uC 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: Thu, 12 May 2016 06:41:28 -0000 Hi David, > On May 12, 2016, at 01:25 , David Lang wrote: >=20 > On Wed, 11 May 2016, moeller0 wrote: >=20 >>> On May 11, 2016, at 17:15 , Toke H=C3=B8iland-J=C3=B8rgensen = wrote: >>>=20 >>> David Lang writes: >>>>=20 >>>> 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. >>>>=20 >>>> 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. >>>=20 >>> Hmm, hadn't thought of that. Damn. Well, guess we'll have to trust = the >>> driver (or make it trustworthy if we can=E2=80=99t). >>=20 >> 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 =E2=80=9Cdegrade=E2= =80=9D the antenna quality of the two hosts to make sure the air-capper = (sounds like a fancy whale species) has better RF visibility=E2=80=A6 >=20 > better antennas on the aircap machine doesn't solve the problem for = two reasons. >=20 > 1. =E2=80=98better' 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. Please read what I wrote again; the better =E2=80=9Cbetter = antennas=E2=80=9D requirement can be fulfilled by making the antennas of = the to be tested device pair worse=E2=80=A6 that should take care of = your concern pretty much. Plus locating the device halfway between the = pair will also give it better RF visibility to signals from both=E2=80=A6 >=20 > 2. your =E2=80=98better' 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. Which is totally fine to a degree as long as the aircap device = will pick up all transmissions/retransmissions of the device pair under = test. Also placing the air-capper at the midpoint will also ameliorate = this concern. >=20 > There=E2=80=99s a reason why RF engineering is half black magic and = experience :-( Oh, if you require perfect I am sure you are right, if we aim = for good enough I have a hunch we can avoid the requirement for at least = the =E2=80=9Cblack=E2=80=9D part of the magic component ;) Best Regards Sebastian >=20 > David Lang