[Cerowrt-devel] treating 2.4ghz as -legacy?

dpreed at reed.com dpreed at reed.com
Tue Dec 17 17:25:57 EST 2013

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.

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

On Tue, Dec 17, 2013 at 12:54 PM, Michael Richardson <[mailto:mcr at sandelman.ca] mcr at sandelman.ca> wrote:

 Fred Stratton <fredstratton at imap.cc> 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/] 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.
- Jim

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