From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-x534.google.com (mail-ed1-x534.google.com [IPv6:2a00:1450:4864:20::534]) (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 1EE923CB35 for ; Mon, 27 Aug 2018 21:56:41 -0400 (EDT) Received: by mail-ed1-x534.google.com with SMTP id k14-v6so167530edr.13 for ; Mon, 27 Aug 2018 18:56:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Txsx3c9jvGzxRYY214e+Ijtt1fLrDRpUApMN8jT5Bwo=; b=LceYYi59RA5ajrmVhQ0vKN4OwZQcwI+y4nkijR1xeQklDWT+J84JHFU7hNYrOQU6yc 0elNzI76ylCaoxGmKOzfxmSJs7WR69FefzmtEx3kuIshUuLoMLHM0PZyEi9yTx6STW0t p71YH1+UnioyqR+XLZxjZF0zp7is8YSmnfXy8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Txsx3c9jvGzxRYY214e+Ijtt1fLrDRpUApMN8jT5Bwo=; b=Y34WAHi/W/TpvmYwGHonSLSsheAubOFOVHgKco8gldwG9msEEOxuCcy40dpYdaZXYY FR1D3x2dg6+rDSW/muOpaREbjdPs+BOBHKMDQsrMyoqCLhgbwodJ4vrgnkJoIHMRq++L 9aNHq0cYpTHLYMVdisB5d12K/9Uz2IRTC0oajWCZwkdMl49f+7rwt6rbuXQaudYBKwRT cjrGSifQyK4MUCFlZmHKo0xAO1gJG+80X3uYQFDv5uuN7mvVSVgVysSsshCV+LurNXr5 t2imjZM7eza6RBr7HJkZQpJEyYSgWsOFL+traocUAvJJ/8lpIxo+ty3sr+6bqCHf5Vxo JPhQ== X-Gm-Message-State: APzg51BKZzwkXH2+Q35Kno4DrBWoNIvCHFg48O33aDBivB6wPozLhDoC z9J2MRcp1003iEsH32zCYpXz4A/ryh0bz1n/MxEHMw== X-Google-Smtp-Source: ANB0VdbSHmFRRseYh5cjL6tzMipO8Ig9saf8RMGJ9PDnJ7oif4zlxaLNWbLZBeiQIfkSq81BPKZ6tznP9+K6OOEvPpo= X-Received: by 2002:a50:91ab:: with SMTP id g40-v6mr19610712eda.50.1535421400157; Mon, 27 Aug 2018 18:56:40 -0700 (PDT) MIME-Version: 1.0 References: <1535286372.35121837@apps.rackspace.com> <2282D31E-CBEF-4B42-A6A6-4D6394EE0DF7@gmail.com> In-Reply-To: From: Bob McMahon Date: Mon, 27 Aug 2018 18:55:36 -0700 Message-ID: To: David Lang Cc: chromatix99@gmail.com, bloat-announce@lists.bufferbloat.net, Make-Wifi-fast , cerowrt-devel@lists.bufferbloat.net, dpreed@deepplum.com, bloat Content-Type: multipart/alternative; boundary="000000000000233413057475272c" Subject: Re: [Bloat] [Make-wifi-fast] [Cerowrt-devel] closing up my make-wifi-fast lab X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Aug 2018 01:56:41 -0000 --000000000000233413057475272c Content-Type: text/plain; charset="UTF-8" Hmm, not sure I understand the distinction. CTS per the AP informs those other transmitters to stay quiet per the CTS NAV. I may be misunderstanding things. Thanks for the continued discussions. It helps to better thoroughly understand the issues. Bob On Mon, Aug 27, 2018, 6:52 PM David Lang wrote: > On Mon, 27 Aug 2018, Bob McMahon wrote: > > > I thought that RTS/CTS would handle the case of hidden nodes, i.e. a > device > > that fails to successfully transmit can resort to RTS/CTS to get the > > receiver to reserve time for it. Also, lack of a RX ack seems ok to > > trigger MAC level retransmits. > > the problem isn't getting the receiver to reserve time for it, it's > getting the > other transmitter(s) to not step on it when it transmits. Those other > transmitters may belong to different people, sharing a channel with your > system > and nothing else. > > David Lang > > > It seems the LBT bug is the collision avoidance overheads when it isn't > > needed, i.e. no other energy would cause the RX PHY to fail its decode > and > > the EDCA backoffs had no benefit, stochastic or otherwise. Optimizing > > that out is said to be not possible from local information only and per > > "shared" spectrum. > > > > Bob > > > > > > On Mon, Aug 27, 2018 at 3:33 PM David Lang wrote: > > > >> On Mon, 27 Aug 2018, Jonathan Morton wrote: > >> > >>> So in practice, it's easier to measure SNR at the receiver, or > >> indirectly by > >>> observing packet loss by dint of missing acknowledgements returned to > >> the > >>> transmitter. > >> > >> Also, there may be other transmitters that the recipient of the packets > >> can hear > >> that you cannot hear, so it's not possible to detect colliding > >> transmissions > >> directly in all cases. > >> > >> This is another trap that digital/wired people fall into that doesn't > >> really > >> apply in the analog/radio world. > >> > >> David Lang > >> > > > --000000000000233413057475272c Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hmm, not sure I understand the distinction.=C2=A0 =C2=A0C= TS per the AP informs those other transmitters to stay quiet per the CTS NA= V.=C2=A0 I may be misunderstanding things.=C2=A0 Thanks for the continued d= iscussions.=C2=A0 It helps to better thoroughly understand the issues.=C2= =A0

Bob=C2=A0

<= div class=3D"gmail_quote">
On Mon, Aug 27, 2018, 6:52 PM Da= vid Lang <david@lang.hm> wrote:<= br>
On Mon, 27 Aug 2018, Bob McMahon wr= ote:

> I thought that RTS/CTS would handle the case of hidden nodes, i.e. a d= evice
> that fails to successfully transmit can resort to RTS/CTS to get the > receiver to reserve time for it.=C2=A0 Also, lack of a RX ack seems ok= to
> trigger MAC level retransmits.

the problem isn't getting the receiver to reserve time for it, it's= getting the
other transmitter(s) to not step on it when it transmits. Those other
transmitters may belong to different people, sharing a channel with your sy= stem
and nothing else.

David Lang

> It seems the LBT bug is the collision avoidance overheads when it isn&= #39;t
> needed, i.e. no other energy would cause the RX PHY to fail its decode= and
> the EDCA backoffs had no benefit, stochastic or otherwise.=C2=A0 =C2= =A0Optimizing
> that out is said to be not possible from local information only and pe= r
> "shared" spectrum.
>
> Bob
>
>
> On Mon, Aug 27, 2018 at 3:33 PM David Lang <david@lang.hm> wrote:=
>
>> On Mon, 27 Aug 2018, Jonathan Morton wrote:
>>
>>> So in practice, it's easier to measure SNR at the receiver= , or
>> indirectly by
>>> observing packet loss by dint of missing acknowledgements retu= rned to
>> the
>>> transmitter.
>>
>> Also, there may be other transmitters that the recipient of the pa= ckets
>> can hear
>> that you cannot hear, so it's not possible to detect colliding=
>> transmissions
>> directly in all cases.
>>
>> This is another trap that digital/wired people fall into that does= n't
>> really
>> apply in the analog/radio world.
>>
>> David Lang
>>
>
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