From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-x52a.google.com (mail-ed1-x52a.google.com [IPv6:2a00:1450:4864:20::52a]) (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 C1B9C3CB36 for ; Mon, 27 Aug 2018 15:59:29 -0400 (EDT) Received: by mail-ed1-x52a.google.com with SMTP id z27-v6so118709edb.10 for ; Mon, 27 Aug 2018 12:59:29 -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=2WHClvJZuRUkGDW4k4Z0YgDl4AZtaJJA5I8GOkC5qe0=; b=JFY+b/J7JcZJf2A7k5vGIVpxs69rVrg1kj5jvz3uD8CwtOxljOSeuvZg+vdF9AbCSD kXis35XDF1mPnvupW1p/AuVogVpAvMFLULDhKhyBuQbjSN2r+YlKHuflFn0RiWgKz2HG acya0ceTBmawX2MHxq7cPwYgdDrB9VnjAyZgI= 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=2WHClvJZuRUkGDW4k4Z0YgDl4AZtaJJA5I8GOkC5qe0=; b=GhsrdcPQ8BqOYwe3v9iwWy6Yxxlkb2HQszkrwdnFEaxXtLvRZh11zAf0YwSqJk0Yop 1Cg03yoOAGeEjX5XHfDHDnbz4BE1pXeS4tBGzzp9rfSQaatIerHgTWOW/EVCgzT5pmnZ Qo6cx0349W9ZTcbFPKs8/cP9W0m4D5XwtKTUwoVvhHefj5XUsbXrsAwegQPRVpxZPz3l R/hHAzatUpTC5K5zP0Dal+rOwgA67waPipWlrrDuZQwgcwn7KBaKsrmp0nM8+UvP+TyO s4Ea5L2ydXt2coXIwTpETZmoWfM0u7RHhgi0euYQDIeJ0ScjyA/J6AOyZV3FdipK38cC X17Q== X-Gm-Message-State: APzg51DvwAjE+lOCAXujAa6LbyPa89T8xnAgzNCrEGkUNpfSe6JU9Cl7 Bh09DVkJKY7rFX07qxsA4sKvHqIK+rpEtgLP+5XvQA== X-Google-Smtp-Source: ANB0VdaBNvTfqoednuQ/EMstXSAZExwPp36T5+5USG7dGRkihi4TH+QRgXE0YUoBRBEHmBpqTNv4Ai/f0tt5daXClss= X-Received: by 2002:a50:eacb:: with SMTP id u11-v6mr19172609edp.7.1535399968756; Mon, 27 Aug 2018 12:59:28 -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 12:59:17 -0700 Message-ID: To: chromatix99@gmail.com Cc: dpreed@deepplum.com, bloat-announce@lists.bufferbloat.net, Make-Wifi-fast , cerowrt-devel@lists.bufferbloat.net, bloat Content-Type: multipart/alternative; boundary="000000000000ba1276057470292b" 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: Mon, 27 Aug 2018 19:59:30 -0000 --000000000000ba1276057470292b Content-Type: text/plain; charset="UTF-8" ok thanks, that's helpful. I guess I thought if astrophysicists can direct image exoplanets a WiFi device should be able to detect superposition - though, talk about some giant hand waving! ;) Bob On Mon, Aug 27, 2018 at 12:45 PM Jonathan Morton wrote: > > On 27 Aug, 2018, at 10:11 pm, Bob McMahon > wrote: > > > > I guess my question is can a WiFi transmitting device rely on primarily > energy detect and mostly ignore the EDCA probability game and rather search > for (or predict) unused spectrum per a time interval such that its digital > signal has enough power per its observed SNR? Then detect "collisions" > (or, "superposition cases" per the RX not having sufficient SINR) via > inserting silent gaps in its TX used to sample ED, i.e. run energy detect > throughout the entire transmission? Or better, no silent gaps, rather > detect if there is superimposed energy on it's own TX and predict a > collision (i.e. RX probably couldn't decode its signal) occurred? If > doable, this seems simpler than having to realize centralized (or even > distributed) media access algorithms a la, TDM, EDCA with ED, token buses, > token rings, etc. and not require media access coordination by things like > APs. > > The software might be simpler, but the hardware would need to be > overspecified to the point of making it unreasonably expensive for consumer > devices. > > Radio hardware generally has a significant TX/RX turnaround time, required > for the RX deafening circuits to disengage. Without those deafening > circuits, the receivers would be damaged by the comparatively vast TX power > in the antenna. > > 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. > > - Jonathan Morton > > --000000000000ba1276057470292b Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
ok thanks, that's helpful.=C2=A0 I guess I thought if = astrophysicists can direct image exoplanets a WiFi d= evice should be able to detect superposition=C2=A0 - though, talk about som= e giant hand waving! ;)

Bob

On Mon, Aug 27, 2018 at 12:45 PM Jonathan Morton <chromatix99@gmail.com> wrote:
<= /div>
> On 27 Aug, 2018, at 10:11 pm, Bob = McMahon <b= ob.mcmahon@broadcom.com> wrote:
>
> I guess my question is can a WiFi transmitting device rely on primaril= y energy detect and mostly ignore the EDCA probability game and rather sear= ch for (or predict) unused spectrum per a time interval such that its digit= al signal has enough power per its observed SNR?=C2=A0 =C2=A0Then detect &q= uot;collisions" (or, "superposition cases" per the RX not ha= ving sufficient SINR) via inserting silent gaps in its TX used to sample ED= , i.e. run energy detect throughout the entire transmission?=C2=A0 Or bette= r, no silent gaps, rather detect if there is superimposed energy on it'= s own TX and predict a collision (i.e. RX probably couldn't decode its = signal) occurred?=C2=A0 If doable, this seems simpler than having to realiz= e centralized (or even distributed) media access algorithms a la, TDM, EDCA= with ED, token buses, token rings, etc. and not require media access coord= ination by things like APs.

The software might be simpler, but the hardware would need to be overspecif= ied to the point of making it unreasonably expensive for consumer devices.<= br>
Radio hardware generally has a significant TX/RX turnaround time, required = for the RX deafening circuits to disengage.=C2=A0 Without those deafening c= ircuits, the receivers would be damaged by the comparatively vast TX power = in the antenna.

So in practice, it's easier to measure SNR at the receiver, or indirect= ly by observing packet loss by dint of missing acknowledgements returned to= the transmitter.

=C2=A0- Jonathan Morton

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