From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp121.iad3a.emailsrvr.com (smtp121.iad3a.emailsrvr.com [173.203.187.121]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 044A221F1AA for ; Tue, 17 Dec 2013 14:25:58 -0800 (PST) Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp8.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id A997B2480E6; Tue, 17 Dec 2013 17:25:57 -0500 (EST) X-Virus-Scanned: OK Received: from app35.wa-webapps.iad3a (relay.iad3a.rsapps.net [172.27.255.110]) by smtp8.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 889452480BD; Tue, 17 Dec 2013 17:25:57 -0500 (EST) Received: from reed.com (localhost.localdomain [127.0.0.1]) by app35.wa-webapps.iad3a (Postfix) with ESMTP id 7688F1801B6; Tue, 17 Dec 2013 17:25:57 -0500 (EST) Received: by apps.rackspace.com (Authenticated sender: dpreed@reed.com, from: dpreed@reed.com) with HTTP; Tue, 17 Dec 2013 17:25:57 -0500 (EST) Date: Tue, 17 Dec 2013 17:25:57 -0500 (EST) From: dpreed@reed.com To: "Jim Gettys" MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_20131217172557000000_52507" Importance: Normal X-Priority: 3 (Normal) X-Type: html In-Reply-To: References: <52AF797E.6030600@imap.cc> <18972.1387302855@sandelman.ca> Message-ID: <1387319157.48330794@apps.rackspace.com> X-Mailer: webmail7.0 Cc: "cerowrt-devel@lists.bufferbloat.net" Subject: Re: [Cerowrt-devel] =?utf-8?q?treating_2=2E4ghz_as_-legacy=3F?= 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 22:25:59 -0000 ------=_20131217172557000000_52507 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable =0AI know it will just trigger raging arguments, but it turns out that 5 GH= z propagates far better in normal housing than does 2.4 GHz.=0A =0AIn parti= cular, actual scientific measurements of penetration of wood, fiberboard, c= oncrete, brick, etc. have been done, and I can provide many of them (they a= re on my computer at home, I am in CA at the moment). The absorption of th= ose materials is the same for both bands.=0A =0ASecond, the Fresnel zone is= 1/4 the size for 5 GHz than 2.4 GHz. This means that energy passes throug= h holes far more intensely (6 dB better) on 5 GHz.=0A =0AFinally, 5 GHz mod= ulations used in WiFi do not include the really lousy 802.11b modulations t= hat are required for beacon signals to have legacy compatibility back to th= e beginning of 802.11b.=0A =0APlease don't repeat this urban legend. Don'= t believe *anything* you read in The Register about EM waves, and don't bel= ieve computer scientists about electrical and electronic engineering.=0A = =0AIn fact, 5 GHz, at the same power, is far superior for indoor signaling.= =0A =0A=0A=0AOn Tuesday, December 17, 2013 1:51pm, "Jim Gettys" said:=0A=0A=0A=0A=0A=0A=0A=0AOn Tue, Dec 17, 2013 at 12:54 PM, Mi= chael Richardson <[mailto:mcr@sandelman.ca] mcr@sandelman.ca> wrote:=0A=0A= =0A Fred Stratton wrote:=0A > For best 5GHz results,= get rid of your walls and doors...=0A=0A > [http://www.theregister.co.uk/2= 011/09/14/virgin_media_superhub_update_modem_mode/] http://www.theregister.= co.uk/2011/09/14/virgin_media_superhub_update_modem_mode/=0A=0AYeah, in my = house, my experience with 5Ghz is that it means the network=0A doesn't work= .=0A=0AI sometimes have a similar situation in my house. And I live in a r= adio quiet area, so I don't face the usual tradeoff of polluted 2.4ghz.=0AB= ut 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 route= r case.=0A=0AAnd the right solution is more routers, and using 5ghz once yo= u have them.=0ASigh...=0A- Jim=0A=0A=0A=0A=0A=0A __________________________= _____________________=0A Cerowrt-devel mailing list=0A[mailto:Cerowrt-devel= @lists.bufferbloat.net] Cerowrt-devel@lists.bufferbloat.net=0A[https://list= s.bufferbloat.net/listinfo/cerowrt-devel] https://lists.bufferbloat.net/lis= tinfo/cerowrt-devel ------=_20131217172557000000_52507 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

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.

=0A

 

=0A

In particular, ac= tual 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.

=0A

 

=0A

Second, the Fresnel zone is= 1/4 the size for 5 GHz than 2.4 GHz.  This means that energy passes t= hrough holes far more intensely (6 dB better) on 5 GHz.

=0A

 

=0A

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

=0A

&nb= sp;

=0A

Please don't repeat this urban l= egend.   Don't believe *anything* you read in The Register about EM wa= ves, and don't believe computer scientists about electrical and electronic = engineering.

=0A

 

=0A

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

=0A

 

=0A= =0A



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

=0A
=0A
=0A

=0A
On Tue, Dec 17, 2013 at 12:54 PM, Mi= chael Richardson <mcr@sandelman.ca> wrote:
=0A=0A

Fred Stratton <fredstratton@imap.cc&= gt; wrote:
> For best 5GHz results, get rid of your walls and door= s...

> http://www.thereg= ister.co.uk/2011/09/14/virgin_media_superhub_update_modem_mode/
=0AYeah, in my house, my experience with 5Ghz is that it means th= e network
doesn't work.
=0A
I sometimes have a similar situation in my= house.  And I live in a radio quiet area, so I don't face the usual t= radeoff of polluted 2.4ghz.
=0A
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 t= he simple one router case.
=0A
=0A
And the right solution is = more routers, and using 5ghz once you have them.
=0A
=0A
Sigh...
=0A
- Jim
=0A
=0A
=0A=0A



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