From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-x22f.google.com (mail-yw0-x22f.google.com [IPv6:2607:f8b0:4002:c05::22f]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 0FDAC3B260 for ; Wed, 11 May 2016 11:33:24 -0400 (EDT) Received: by mail-yw0-x22f.google.com with SMTP id g133so46082083ywb.2 for ; Wed, 11 May 2016 08:33:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc; bh=XCAWTA3GfWJzxLda3dUgJGty959WwPSIlypEixs+xtY=; b=rx4kj9AEo1qb34DBneMLckgUYn+IIMGV8XFIhbSQqhnH7ipVWLTaPi81JRCMI6zdHq GHt1xkRYD1xbHfbZFA8A6Hy7XiXI5czTG/iiKZf8cpy8jks8O6BBY4MPrG0OAkl3odBL ks9q9odg980ZpUGOMyNcSpqL7EgXjBRKse5PuX5uESWorqoGYe3cMlPVls0OKDY20iDe qmzK3QIeaMXWAQ0/e8OFLjNiTCrilaTHY+SwkwLliCK6EVAfpV6bVIA/6hhc9B6GGcQI earj8e/n2IJt1i/l0W+EPpTpzB1nHXDnCV4gW3Co/ts488J/D3SOcBPJwj0UL1qBcJDO 1Erw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc; bh=XCAWTA3GfWJzxLda3dUgJGty959WwPSIlypEixs+xtY=; b=JbQhkA+4mLKBi/cGFilq1K9/Vmcg284HVfebMNwGkMBWLpJffwZ7hAsVd1irefJu14 SFwPYlfb5xv3BcJuK8gShVDB3TW+J4MM1oTCvyUDJQEa3AfSVLfdWXO6joaKCuH/jf9f 34GjPt48FKlxn0rizNtx08/n0qIafbKf0PG7X89+VFgeInLTEGR7LbJAlCKwONT9h+Tp 6T5X18qCEASQ2G9ZtcMc9XNJadjx5/p5SH5qtlwiMSPi/a5Sdyu9NPfrhn3mdFDkUsXc +EaxuKfc6/dNNi91gX+egvt58E7f3ZooY6FttPBA1nR2UU9YZyZ8uQ+kAoUn7d0GdRr0 daWw== X-Gm-Message-State: AOPr4FUI7uHIcLVcZ2+LSfFbW/bx2VyJs1Tmr0jVaephFWfbfk5rB3SdZg0Hf9bjeWWrTmHLwdp7C9kyGhpqgA== MIME-Version: 1.0 X-Received: by 10.129.74.86 with SMTP id x83mr2208004ywa.38.1462980804592; Wed, 11 May 2016 08:33:24 -0700 (PDT) Received: by 10.37.74.134 with HTTP; Wed, 11 May 2016 08:33:24 -0700 (PDT) In-Reply-To: <874ma4ljfz.fsf@toke.dk> References: <871t58n5wk.fsf@toke.dk> <87futolndh.fsf@toke.dk> <874ma4ljfz.fsf@toke.dk> Date: Wed, 11 May 2016 17:33:24 +0200 Message-ID: From: Luca Muscariello To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Cc: "make-wifi-fast@lists.bufferbloat.net" Content-Type: multipart/alternative; boundary=001a114c8c3a2be2c8053292c34e 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 15:33:25 -0000 --001a114c8c3a2be2c8053292c34e Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable What I did was just a hack to demonstrate the principle. Today 802.11n is very different assuming you only use HT. The APware project at MIT will give you some good hints. Short term fairness was bad, long term fairness very good. Short term I believe is very difficult to achieve because of the EDCF. Short term fairness can be very good only using time slotted MAC. On Wednesday, 11 May 2016, Toke H=C3=B8iland-J=C3=B8rgensen = wrote: > Luca Muscariello > writes: > > > Do you happen to recall what precision you achieved or how much the > > precision was really important? Several papers seem to assume that ver= y > > high precision is not terribly important since it all evens out in the > > end, and I can see how that could be true; but would like to have it > > confirmed :) > > > > what do you mean with precision? > > Do you mean in measuring the PHY rate? > > Short term vs long term measurements? else? > > Yes, in measuring the rate. Was this a per-packet thing, and were you > actually able to get information sufficiently accurate to achieve the > desired level of fairness? And by what mechanism? Was this in the driver > or higher up in the stack? > > > The hard part was adaptiveness. Correlation between the speed of the > > STA, the PHY rate controller and quanta updates in SFQ. > > Yes, that's what I though :) > > > Ideally we were trying to approach something like > > downlink channel scheduling in HSDPA where you have slotted time TX > > and polling. A slot in HSDPA (but also LTE) is a burst of fixed time > size of several packets. > > Similar to what you want to achieve in your email point 1. > > Yeah, if we could just switch to TDMA a lot of things would be much > simpler... > > > As a side note, there are several differences in aggregates in 802.11n > > and HSDPA/LTE as in the latter the scheduler can send an aggregate > > containing packets using different modulation/coding schemes to reach > > different stations with a single aggregate transmission. > > Neat. > > > For the records, this feature was rejected in the 802.11n amendement > > but discussed by the group as it makes the chip more expensive. > > Right; not terribly surprised, but still a shame. > > -Toke > --001a114c8c3a2be2c8053292c34e Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable What I did was just a hack to demonstrate the principle. Today 802.11n is v= ery different assuming you only use HT.
The APware project at MIT will = give you some good hints.

Short term fa= irness was bad, long term fairness very good.

Short term= I believe is very difficult to achieve because of the EDCF.=C2=A0 Short te= rm fairness can be very good only using time=C2=A0slotted MAC.

On Wednesday, 11 May 2016, Toke H=C3=B8iland-J=C3=B8rgensen <toke@toke.dk> wrote:
Luca Muscariello <luca.muscariel= lo@gmail.com> writes:

>=C2=A0 Do you happen to recall what precision you achieved or how much = the
>=C2=A0 precision was really important? Several papers seem to assume th= at very
>=C2=A0 high precision is not terribly important since it all evens out = in the
>=C2=A0 end, and I can see how that could be true; but would like to hav= e it
>=C2=A0 confirmed :)
>
> what do you mean with precision?
> Do you mean in measuring the PHY rate?
> Short term vs long term measurements? else?

Yes, in measuring the rate. Was this a per-packet thing, and were you
actually able to get information sufficiently accurate to achieve the
desired level of fairness? And by what mechanism? Was this in the driver or higher up in the stack?

> The hard part was adaptiveness. Correlation between the speed of the > STA, the PHY rate controller and quanta updates in SFQ.

Yes, that's what I though :)

> Ideally we were trying to approach something like
> downlink channel scheduling in HSDPA where you have slotted time TX > and polling. A slot in HSDPA (but also LTE) is a burst=C2=A0 of fixed = time size of several packets.
> Similar to what you want to achieve in your email point 1.

Yeah, if we could just switch to TDMA a lot of things would be much
simpler...

> As a side note, there are several differences in aggregates in 802.11n=
> and HSDPA/LTE as in the latter the scheduler can send an aggregate
> containing packets using different modulation/coding schemes to reach<= br> > different stations with a single aggregate transmission.

Neat.

> For the records, this feature was rejected in the 802.11n amendement > but discussed by the group as it makes the chip more expensive.

Right; not terribly surprised, but still a shame.

-Toke
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