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

[Jim Gettys <jg@freedesktop.org>]

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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
> 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" <jg@freedesktop.org>
> said:
>
>
>
> On Tue, Dec 17, 2013 at 12:54 PM, Michael Richardson <mcr@sandelman.ca>wrote:
>
>>
>> Fred Stratton <fredstratton@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/
>>
>> 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
>
>>
>>
>>
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>>
>

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