From owner-freebsd-wireless@FreeBSD.ORG  Wed Dec  4 03:32:40 2013
Return-Path: <owner-freebsd-wireless@FreeBSD.ORG>
Delivered-To: freebsd-wireless@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id A349CD5C;
 Wed,  4 Dec 2013 03:32:40 +0000 (UTC)
Received: from mail-pd0-x22f.google.com (mail-pd0-x22f.google.com
 [IPv6:2607:f8b0:400e:c02::22f])
 (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits))
 (No client certificate requested)
 by mx1.freebsd.org (Postfix) with ESMTPS id 70A061CD8;
 Wed,  4 Dec 2013 03:32:40 +0000 (UTC)
Received: by mail-pd0-f175.google.com with SMTP id w10so21509002pde.34
 for <multiple recipients>; Tue, 03 Dec 2013 19:32:40 -0800 (PST)
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:content-type;
 bh=1Zy65UNbbuJnZzE7mkcV8IzRjdbScoHS18WN40rF0l0=;
 b=vev52JzmmGa5U18Cx2AO9euDb/pv0PuB3t0i+47HRmbzTZZgvg1hvOthU6bjmTDTA/
 uJaPQTk4clpTUkfrzbWpBmmxMaVBnTIacdfU8NomjHzXkwYKnAdf8k+x38Zg8uAXbeSJ
 kGbeyLQknD6jH/Py7eDHYn79InZtRSfRncg4GxlCjbYGV3GYxegyRRcUDmDvHvJ4XGcQ
 xp6SLr3J0dky4YqEiIyqg6/dcuXlvcVNHCgyU5BWvb35AagvxU9Sgo2R2t2VGboxmA3V
 Qa5D2795BWHtxP0uuQgusR+1uRqj+5yy3pxMi3zkWz9+ufwbNAczTekXEBNrBi7L5lOv
 GhVQ==
MIME-Version: 1.0
X-Received: by 10.66.13.138 with SMTP id h10mr14850329pac.148.1386127959982;
 Tue, 03 Dec 2013 19:32:39 -0800 (PST)
Received: by 10.68.13.226 with HTTP; Tue, 3 Dec 2013 19:32:39 -0800 (PST)
In-Reply-To: <46B1EFC5-1AA4-4E51-B199-D4CDACEEA0AC@netgate.com>
References: <CAC6a1Dh_vwAMNucd+FBB-3CFKpmW3SCRwBrLZfCv+aL5=SoJ2Q@mail.gmail.com>
 <CAJ-VmonK6zp0tDaeKZatDwu=pr6RKzFC=An5YnVMc3XK1oeNUQ@mail.gmail.com>
 <CAC6a1DiPrA+ksO+LQu+cRgB0jYnz=BcFfMBCmFaiF316OieOxw@mail.gmail.com>
 <CAJ-VmomMXfPxVJLkvUS4=VDe_oiCNgbXa7Aj=E9QkYHJ=gtUag@mail.gmail.com>
 <46B1EFC5-1AA4-4E51-B199-D4CDACEEA0AC@netgate.com>
Date: Wed, 4 Dec 2013 11:32:39 +0800
Message-ID: <CAC6a1Dhuf5AYTYnjo82tO7LL2phBOijS=wTWBdq79NXk6exd5Q@mail.gmail.com>
Subject: Re: Channel interference scan and manual selection
From: Tek Wiz <tx2023@gmail.com>
To: Jim Thompson <jim@netgate.com>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: quoted-printable
X-Content-Filtered-By: Mailman/MimeDel 2.1.17
Cc: "freebsd-wireless@freebsd.org" <freebsd-wireless@freebsd.org>
X-BeenThere: freebsd-wireless@freebsd.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: "Discussions of 802.11 stack,
 tools device driver development." <freebsd-wireless.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-wireless>, 
 <mailto:freebsd-wireless-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-wireless/>
List-Post: <mailto:freebsd-wireless@freebsd.org>
List-Help: <mailto:freebsd-wireless-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-wireless>, 
 <mailto:freebsd-wireless-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 04 Dec 2013 03:32:40 -0000

Yes, the interference can be calculated by averaging the beacon RSSI (dB)
of the overlapping channels, e.g. for channel 6, the beacon RSSI of
channels 4, 5, 6, 7, 8 are averaged. Normally channels 1, 6, and 11 are
chosen, although other channels may have less interference, in order to be
a 'good neighbor'.


On Wed, Dec 4, 2013 at 11:03 AM, Jim Thompson <jim@netgate.com> wrote:

>
> On Dec 3, 2013, at 7:56 PM, Adrian Chadd <adrian@freebsd.org> wrote:
>
> > Now, ideally it'd actually check the channel for interference and
> > channel busy status, and use _that_ metric.
>
> Ideally, it would attempt to get co-channel with other APs on the same
> channel.
>
> Especially in 2.4GHz (or any of the 5GHz bands).
>
> Because you would *much* rather share the air (via collision avoidance)
> than raise the noise floor for someone (everyone) else.
>
> And, given that everyone has a DC receiver these days, there are NO
> =93non-overlapping channels=94.
>
> jim
>
>