From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-x231.google.com (mail-wi0-x231.google.com [IPv6:2a00:1450:400c:c05::231]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 4EDD321F1AA for ; Tue, 17 Dec 2013 14:32:15 -0800 (PST) Received: by mail-wi0-f177.google.com with SMTP id cc10so4385013wib.4 for ; Tue, 17 Dec 2013 14:32:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=wyZpUVKCVUVF/ZZw6ejEsg9fY9GyiLbu4n5VwIVQ9Y4=; b=cL+y5KX6UCOFGK2HRkYQY4poRfXJLJqtFRMEHJHwIlF8a2ctSx+v3owPda46SxyzFy 1zLurqHG8scijXlnt8xku1IfHcEoIHV2YntzZCl6j17ku+bvU/J0rbD1d/d07pSowvdu zVOf2fm1msUTrWxa2oa2xVe3v8nT6UcHJdn+nszPNTGD5G9h9bIxlZEDOVvpiq+mzMYx GHvn2e8Dd7Cyu5WVCJO36JctX4rSmaeizyjlZRsrkKijF9Gli2b/79Afe9QaNvXf3pvK ezQOQnhWYGXXaC5PfCP6t/NFSQtSWainVe0KjNbTmPbJc/pKpMbevOC5EtwpRESeDjmo hsEQ== MIME-Version: 1.0 X-Received: by 10.180.12.70 with SMTP id w6mr5338598wib.4.1387319533306; Tue, 17 Dec 2013 14:32:13 -0800 (PST) Sender: gettysjim@gmail.com Received: by 10.227.134.74 with HTTP; Tue, 17 Dec 2013 14:32:13 -0800 (PST) In-Reply-To: <1387319157.48330794@apps.rackspace.com> References: <52AF797E.6030600@imap.cc> <18972.1387302855@sandelman.ca> <1387319157.48330794@apps.rackspace.com> Date: Tue, 17 Dec 2013 17:32:13 -0500 X-Google-Sender-Auth: 7QQgkphCMNk2l-hTsD_hyWGwgKo Message-ID: From: Jim Gettys To: David P Reed Content-Type: multipart/alternative; boundary=001a11c223acf90dbb04edc27fe8 Cc: "cerowrt-devel@lists.bufferbloat.net" Subject: Re: [Cerowrt-devel] treating 2.4ghz as -legacy? X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 Dec 2013 22:32:15 -0000 --001a11c223acf90dbb04edc27fe8 Content-Type: text/plain; charset=ISO-8859-1 On Tue, Dec 17, 2013 at 5:25 PM, wrote: > I know it will just trigger raging arguments, but it turns out that 5 GHz > propagates far better in normal housing than does 2.4 GHz. > > > > In particular, actual scientific measurements of penetration of wood, > fiberboard, concrete, brick, etc. have been done, and I can provide many of > them (they are on my computer at home, I am in CA at the moment). The > absorption of those materials is the same for both bands. > > > > Second, the Fresnel zone is 1/4 the size for 5 GHz than 2.4 GHz. This > means that energy passes through holes far more intensely (6 dB better) on > 5 GHz. > > > > Finally, 5 GHz modulations used in WiFi do not include the really lousy > 802.11b modulations that are required for beacon signals to have legacy > compatibility back to the beginning of 802.11b. > > > > Please don't repeat this urban legend. Don't believe *anything* you read > in The Register about EM waves, and don't believe computer scientists about > electrical and electronic engineering. > > > > In fact, 5 GHz, at the same power, is far superior for indoor signaling. > Dave, I'm happy to believe you... But then my personal observations of behavior of 2.4 vs. 5ghz need some explanation... Could be 1) the antenna involved, 2) or the transmit power is not the same. 3) the system's reporting of signal strength is defective (but my empirical observations of what works best has seemed to be correlated with that). I'm not likely to be able to do much about 1) (until we have different routers to play with, anyway...) How do we get to the bottom on 2) or 3)? - Jim > > > > > On Tuesday, December 17, 2013 1:51pm, "Jim Gettys" > said: > > > > On Tue, Dec 17, 2013 at 12:54 PM, Michael Richardson wrote: > >> >> Fred Stratton wrote: >> > For best 5GHz results, get rid of your walls and doors... >> >> > >> http://www.theregister.co.uk/2011/09/14/virgin_media_superhub_update_modem_mode/ >> >> Yeah, in my house, my experience with 5Ghz is that it means the network >> doesn't work. >> > I sometimes have a similar situation in my house. And I live in a radio > quiet area, so I don't face the usual tradeoff of polluted 2.4ghz. > But it does make it very hard to simply recommend 5 over 2.4ghz; there is > no single "right answer"; the answer is "it depends" for the simple one > router case. > And the right solution is more routers, and using 5ghz once you have > them. > Sigh... > - Jim > >> >> >> >> _______________________________________________ >> Cerowrt-devel mailing list >> Cerowrt-devel@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/cerowrt-devel >> > --001a11c223acf90dbb04edc27fe8 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable



On Tue, Dec 17, = 2013 at 5:25 PM, <dpreed@reed.com> wrote:

I= know it will just trigger raging arguments, but it turns out that 5 GHz pr= opagates far better in normal housing than does 2.4 GHz.

=A0

In particular, actual scientific measur= ements of penetration of wood, fiberboard, concrete, brick, etc. have been = done, and I can provide many of them (they are on my computer at home, I am= in CA at the moment). =A0The absorption of those materials is the same for= both bands.

=A0

Second, the Fresnel zone is 1/4 the siz= e for 5 GHz than 2.4 GHz. =A0This means that energy passes through holes fa= r more intensely (6 dB better) on 5 GHz.

=A0

Finally, 5 GHz modulations used in WiFi= do not include the really lousy 802.11b modulations that are required for = beacon signals to have legacy compatibility back to the beginning of 802.11= b.

=A0

Please don't repeat this urban lege= nd. =A0 Don't believe *anything* you read in The Register about EM wave= s, and don't believe computer scientists about electrical and electroni= c engineering.

=A0

In fact, 5 GHz, at the same power, is f= ar superior for indoor signaling.


Dave,

I'm happy to believe you...

But then my pers= onal observations of behavior of 2.4 vs. 5ghz need some explanation...

Could be=A0
=A0 =A01) the antenna involved,=A0
=A0 =A02) or the transmit power is not the same.
=A0 =A03) the system's reporting of signal strength is defe= ctive (but my empirical observations of what works best has seemed to be co= rrelated with that).

I'm= not likely to be able to do much about 1) (until we have different routers= to play with, anyway...)

How do we get to the bottom on 2) or 3)?
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0- Jim

=A0



On Tuesday, December 17, 2013 1= :51pm, "Jim Gettys" <jg@freedesktop.org> said:



On Tue, Dec 17, 2013 at 12:54 PM, Michael Richar= dson <mcr@sandelman.ca> wrote:

Fred Stratton <fredstratton@imap.cc> wrote:
> For be= st 5GHz results, get rid of your walls and doors...

> http://www.theregister.co.uk/2011/09/14/virgin_me= dia_superhub_update_modem_mode/

Yeah, in my house, my experience with 5Ghz is that it means the network
= doesn't work.
I sometimes have a similar situation in my h= ouse. =A0And I live in a radio quiet area, so I don't face the usual tr= adeoff of polluted 2.4ghz.
But it does make it very hard to simply reco= mmend 5 over 2.4ghz; there is no single "right answer"; the answe= r is "it depends" for the simple one router case.
And the right solution is more routers, and using 5ghz once you have t= hem.
Sigh...
- Jim



_______________________________________________
Cerow= rt-devel mailing list
Cerowrt-devel@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/cerowrt-devel

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