From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-x533.google.com (mail-ed1-x533.google.com [IPv6:2a00:1450:4864:20::533]) (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 451C13CB37 for ; Mon, 27 Aug 2018 21:47:09 -0400 (EDT) Received: by mail-ed1-x533.google.com with SMTP id h33-v6so176974edb.5 for ; Mon, 27 Aug 2018 18:47:09 -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=hSzbcEMLysbAx6GKius+a/q+RMCPr4V+iyobleLG78I=; b=ZxARXaNv28xhf3oOLqJDaCVYjBHmSZayZP+XGgDM3Zp0rmrBHADjcGJpeWBoGDi9QK 8F7k4qfF5FFdgIIUnSG7iTBMh4i2fL0w43ooQpf2tBvVMU7r8JB7ZOEUeRUEL5vdhRfq PAl4KGPF0VGv2KeirEgA5kfxZy6Ac/aGhfFt4= 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=hSzbcEMLysbAx6GKius+a/q+RMCPr4V+iyobleLG78I=; b=hD3gTkmOVRHDW5CywSJCIeCXiH7/XX6jvR+rj3RzdDrpn596RH76DDQQINs1m9WP2O sMRH+PJl2HVpWKzjvgUaG2iUhcUGeg97qE2IRS+Luq7pqBbFopGvCR8OVze84620Smp/ pp5kqmL15tYdWmzjxcfriAErdbKHWTwBskD/q1WL2kUE5BK84eo4Bmq6NpBnWoL1syNv 7M7E0Kjum3VsEShZkUIrrl6/ZfAMcrQscbNSH3i2S1R44eY/PYPwfZ5d9ybQv31Bl440 QHsXfZTJfOesPVPutPhjWFbXzfAV9hLMxkGNdKvZ7aGl27cxZWAQBrYf3/l2y/GTpQ6Z Tz7A== X-Gm-Message-State: APzg51Ayk3hbG/vbXv75Fvo/BOdne1lpxjqpnXwBTaxB/h2HMcabvky0 nHrYNqZKE8aHHamqkcJ6Sw2J0oQ1YRX0PBVLFiOZSQ== X-Google-Smtp-Source: ANB0VdYD8IRDWparxf9FgSGk+NNFWlPmFDS+2GGk1+IIvK8mbzWWxCrEBjY/S/WwqRqm47TaprAjxhda4ou8gqpmJNk= X-Received: by 2002:a50:eacb:: with SMTP id u11-v6mr20183104edp.7.1535420828288; Mon, 27 Aug 2018 18:47:08 -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 18:46:12 -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="0000000000000d2fa605747505b8" Subject: Re: [Make-wifi-fast] [Bloat] [Cerowrt-devel] closing up my make-wifi-fast lab 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: Tue, 28 Aug 2018 01:47:09 -0000 --0000000000000d2fa605747505b8 Content-Type: text/plain; charset="UTF-8" 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. 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 > --0000000000000d2fa605747505b8 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
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.=C2=A0 Also, = lack of a RX ack seems ok to trigger MAC level retransmits.

It seems the LBT bug is the collision a= voidance overheads when it isn't needed, i.e. no other energy would cau= se the RX PHY to fail its decode and the EDCA backoffs had no benefit, stoc= hastic or otherwise.=C2=A0 =C2=A0Optimizing that out is said to be not poss= ible from local information only and per "shared" spectrum.=C2=A0=

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 ind= irectly 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 transmis= sions
directly in all cases.

This is another trap that digital/wired people fall into that doesn't r= eally
apply in the analog/radio world.

David Lang
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