From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-x22b.google.com (mail-yw0-x22b.google.com [IPv6:2607:f8b0:4002:c05::22b]) (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 8872F3B260 for ; Thu, 12 May 2016 04:21:56 -0400 (EDT) Received: by mail-yw0-x22b.google.com with SMTP id g133so66302282ywb.2 for ; Thu, 12 May 2016 01:21:56 -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=zaJqdR3BoSgd/rnYz1kOhyJsGL31gS+uyla3ntF1DFw=; b=pB9XYfxzJJ3FmNZOTpjYPgC4axkxx+/NtKvEIS/CCsB+XOZ8BVztgZF6tgQw8jxMtU VjsZr8xpFKthlv5DtOpybEsmZj+AKeodKESIqq2o4fs5MLEsnuS5fR1WhZ5TZarMzOAr 9aGy+goHFCjCpzFfJWC1ZzMDq/1AdOLmrMevDizxFKRyx8F0aRT/OKUw006LYATVWFND DmuYVdtZ8zVdzF+cKweEIXblj/5PYvQBb+4A1O+jqfb7bAlea0vWlqDeHFVhaLxzxSVm ooUD4+aSeu4AX5VPQsg4zPTB26llnnKco0/iMRzVosDGWuo8LBoMadfpNHQbIBu48yOS ZM0A== 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=zaJqdR3BoSgd/rnYz1kOhyJsGL31gS+uyla3ntF1DFw=; b=M1OXVdMx18s/11MOXpU6jn7eaRZylYdmVxu3ijpcIIQNNehn6Ydjrui+XezKuvW+3j amqSdRoPi8jt0rsAl9eT4zPCSz6nOwWU2WSUDoiUXM1FbbqkQ/uv+hvqm0cdDHjHcsfG 6jE1OPjs3nQVfok2VtGmzPpTPsmZ6LgaaX6wXl+ObIxS9KIwWGxCydBVoFbZS7YwJ3kt IoiRSX1FQMXOZorWAn9xIvElLwIwhybvX3FfKOlp3DoDyi+uEBeI829l9OcP1f3WTQwR IKdH3nJWM30Ns6VWux78gc7f62hCgQ8zlACgNQBtotJ4jsW3Cc8KmnkWdG3DeiDp0LUB iUYQ== X-Gm-Message-State: AOPr4FXP74cpX9ixh2hujclkWsvxWDZqJ318ad+tIL3XnxwRqI32dcmJErH7a8apWYnyRYJkmACWA1I8T9aYcw== MIME-Version: 1.0 X-Received: by 10.37.201.71 with SMTP id z68mr3676643ybf.124.1463041315706; Thu, 12 May 2016 01:21:55 -0700 (PDT) Received: by 10.37.74.134 with HTTP; Thu, 12 May 2016 01:21:55 -0700 (PDT) In-Reply-To: References: <871t58n5wk.fsf@toke.dk> Date: Thu, 12 May 2016 10:21:55 +0200 Message-ID: From: Luca Muscariello To: Dave Taht Cc: David Lang , "make-wifi-fast@lists.bufferbloat.net" Content-Type: multipart/alternative; boundary=001a114d74f8ea259b0532a0d94e 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 08:21:56 -0000 --001a114d74f8ea259b0532a0d94e Content-Type: text/plain; charset=UTF-8 I share your skepticism about beam forming. It depends of course on the kind of usage you make of wifi. If it's to cover a city in a small cell optimized deployment I don't think beam forming is going to help. When cell traffic is high only TDMA can help. If you use beam forming to reach non mobile users and traffic is not to high it's going to give best performance. Both are valuable use cases with economic incentives behind. The first one is more difficult and time fairness is gonna help a lot there as the average cell throughput is gonna be a lot better. On Wed, May 11, 2016 at 8:13 PM, Dave Taht wrote: > On Wed, May 11, 2016 at 9:41 AM, Dave Taht wrote: > > On Wed, May 11, 2016 at 9:09 AM, Luca Muscariello > > wrote: > >> Correct, but in between that time and now a lot has been done in > different > >> areas but not much on this point. > >> The fact that some part of the industry is looking at LTE-U is also > because > >> 802.11 standard is not good enough. > > > > What do you think of LTE-LAA? > > > > I do think very strongly that actual usage of 802.11 can be made > > vastly more efficient, that we can use up a great deal of the mac > > currently being left unused, and schedule txops way more efficiently - > > and that I'd love to test with michal's patch set against the LTE-U > > tests cablelabs, etc which did > > > > 100 stations before (stock): > > > > http://blog.cerowrt.org/flent/drr/10tothe5.svg > > > > after > > > > http://blog.cerowrt.org/flent/drr/newcode.svg > > Seeing "only" 250ms worth of delay for 100 stations here was what > kicked off a prior thread, my understanding of a theoretical base > number here would be about 70ms. (?) > I miss many details about these tests. And probably I missed the thread... Can you give me pointers? > > ... > > Adding in mu-mimo to the picture makes my head hurt. My understanding > of how mu-mimo is supposed to work is you have to have accumulated > 2-3ms worth of packets for the number of stations you are going to > schedule before it's worthwhile at all. > > The stations are going to typically be limited to 1 antenna (most > laptops have 2), I think. So a 4 antenna system *could* send to 4 > stations if all have traffic pending... at a cost of a (proposed, I > don't agree with it) 500 usec sounding phase every 10ms. My take on > that is you should only sound when you actually have some potential to > share that many flows to that many stations, sounding being more of an > aspect of rate control, also. > > Having only 2 stations that you can mu-mimo to seems like a lose generally. > > Based on normal traffic behaviors the stations that could be sent to > varies, and gang scheduling with lots of stations would require even > more soundings... > > ... > > I don't have a lot of hope for mu-mimo, although what I kind of expect > is the work done here will end up marketed as due to that feature in > the wave2 stuff... > --001a114d74f8ea259b0532a0d94e Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I share your skepticism about beam forming. It depends of = course on the kind
of usage you make of wifi. If it's to cover a ci= ty in a small cell optimized deployment=C2=A0
I don't think b= eam forming is going to help. When cell traffic is high only TDMA can help.=

If you use beam forming to reach non mobile users= and traffic is not to high it's going to=C2=A0
give best per= formance.

Both are valuable use cases with economi= c incentives behind.
The first one is more difficult and time fai= rness is gonna help a lot there
as the average cell throughput is= gonna be a lot better.

=C2=A0

On Wed, May 11, 2016 at 8:13 PM= , Dave Taht <dave.taht@gmail.com> wrote:
On Wed, May 11, 2016 at 9:41 AM, Dave Tah= t <dave.taht@gmail.com> wr= ote:
> On Wed, May 11, 2016 at 9:09 AM, Luca Muscariello
> <luca.muscariello@gma= il.com> wrote:
>> Correct, but in between that time and now a lot has been done in d= ifferent
>> areas but not much on this point.
>> The fact that some part of the industry is looking at LTE-U is als= o because
>> 802.11 standard is not good enough.
>
> What do you think of LTE-LAA?
>
> I do think very strongly that actual usage of 802.11 can be made
> vastly more efficient, that we can use up a great deal of the mac
> currently being left unused, and schedule txops way more efficiently -=
> and that I'd love to test with michal's patch set against the = LTE-U
> tests cablelabs, etc which did
>
> 100 stations before (stock):
>
> http://blog.cerowrt.org/flent/drr/10tothe5.svg
>
> after
>
> http://blog.cerowrt.org/flent/drr/newcode.svg<= br>
Seeing "only" 250ms worth of delay for 100 stations here w= as what
kicked off a prior thread, my understanding of a theoretical base
number here would be about 70ms. (?)

I = miss many details about these tests. And probably I missed the thread...
Can you give me pointers?

=C2=A0

...

Adding in mu-mimo to the picture makes my head hurt. My understanding
of how mu-mimo is supposed to work is you have to have accumulated
2-3ms worth of packets for the number of stations you are going to
schedule before it's worthwhile at all.

The stations are going to typically be limited to 1 antenna (most
laptops have 2), I think. So a 4 antenna system *could* send to 4
stations if all have traffic pending... at a cost of a (proposed, I
don't agree with it) 500 usec sounding phase every 10ms. My take on
that is you should only sound when you actually have some potential to
share that many flows to that many stations, sounding being more of an
aspect of rate control, also.

Having only 2 stations that you can mu-mimo to seems like a lose generally.=

Based on normal traffic behaviors the stations that could be sent to
varies, and gang scheduling with lots of stations would require even
more soundings...

...

I don't have a lot of hope for mu-mimo, although what I kind of expect<= br> is the work done here will end up marketed as due to that feature in
the wave2 stuff...

--001a114d74f8ea259b0532a0d94e--