[amsat-bb] Re: Is Wi-Fi Headed toward an Early Grave?
ko6th_greg at hotmail.com
Wed Dec 13 00:34:48 PST 2006
802.11n, as currently written, also has some qualities that don't work very
well in the 2.4 ghz band. A big problem is that to get full bandwidth, 11n
"bonds" two adjacent channels together, taking up a 40 mhz swath of
spectrum. Since for much of the planet the entire band is only 50 mhz wide,
this means that there is only one high performance channel. If you have
several networks nearby (and "nearby" is larger than it was before, as you
note), then the contention for airtime could be a problem. The 5 ghz band
has 23-ish real channels, giving ample space for multiple networks to
co-exist even at the higher rate. Channel bonding on 2.4 also tends to take
out Bluetooth communications. So, if the bonding stays in the final spec
next year, I think N will head for 5 ghz, especially in the enterprise space
where the cost differential for parts isn't as big of a barrier, and take
the rest of Wi-Fi with it. Yes, the physics is better for 2.4 for going
through stuff, but interference will win out here.
But the deciding factor may be in the consumer space. They are, after all,
in our back yards (if not in our own living rooms). I think there are a
couple of factors that will determine the eventual fate of 2.4 ghz wireless
communications there. The big issue here is whether the need for high
bandwidth home networking will take off. If it doesn't, we're good. If it
does to a limited degree, the channel problem won't count, and then it's
just a "simple" matter to solve the interoperability problems that plague
the current crop of products. The enterprise space should drive that, and
then we're screwed. Cheap parts, good physics, lots of bandwidth, but not
enough congestion to be a (networking) problem. Worst case scenario.
But, if things take off and everybody has a high bandwidth home network,
there could be quite a mess for a little while, before the cost premium for
5 ghz is overtaken by the need for quiet bandwidth and a
bigger-numbers-is-always-better marketing plan. Then the rush will be to 5
ghz, and we'll be left alone. But, how long can we wait?
The wild card in my opinion is Wi-Max (802.16), which is intended to be the
"last mile" connection for service prividers. If this wins, it will be the
death blow to BPL (Yeah!), and will ease the pressure to blanket Wi-Fi
across every major city on the planet. I believe Wi-Max is on licensed
frequencies outside of the Ham bands, so this would be a really good thing.
At least, that's what my crystal ball says. But the ball is foggy, and
having a clear 2.almost-4 ghz allocation across the planet would be a good
thing in any case.
----Original Message Follows----
From: Trevor <m5aka at yahoo.co.uk>
To: AMSAT BB <amsat-bb at amsat.org>
Subject: [amsat-bb] Re: Is Wi-Fi Headed toward an Early Grave?
Date: Tue, 12 Dec 2006 22:27:49 +0000 (GMT)
802.11n will increase usage of 2.4 GHz. If you want decent range 2.4 GHz is
band to use not 5 GHz.
We will continue to see increasing use of 2.4 GHz for a whole range of
It's why we need an Amateur Satellite allocation at 2490-2400 MHz in
to 2400-2402 MHz.
73 Trevor M5AKA
--- Bill Ress <bill at hsmicrowave.com> wrote:
> Thought I'd pass along an interest article (in PC Magazine) entitled "Is
> Wi-Fi Headed toward an Early Grave?"
> A rather mixed prediction since the article predicts 802.11n will
> replace WiFi and 802.11n can operate in both 2.4 and 5 GHz allocations.
> We can only hope that 802.11a (5 GHz) and 802.11n operating at 5 GHz
> will take some of the heat off our 2.4 GHz band. The 5 GHz allocation
> offers more immunity to co-interference and allows for higher data
> rates. Perhaps the availability of still higher data rates will offer
> incentive (over the long term) to get users to opt for the higher
> frequency (above 2.4 GHz) networks.
> Maybe I'm overly optimistic??
> Regards...Bill - N6GHz
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