James G. Sack (jim) wrote:
Gus Wirth wrote:
Last night at the March Mingle I saw Phil Karn
<http://cache.qualcomm.com/karn/> and we had a discussion about some new
wireless repeaters he bought, specifically the Miraki Mini Repeater
(available from <http://www.netequality.com/>). One of his comments was
its usefulness in disaster scenarios, where you could have these things
matched up in a little box with a battery and deployed throughout a
building. My observation was that EXIT signs already provide the
infrastructure necessary to make this happen. They are nearly ubiquitous
in commercial buildings and they already have batteries in them that
could provide power for up to several hours. A retrofit kit for existing
signs and builtin for new signs could give a building complete wireless
coverage both in normal usage and in emergency conditions for a very low
cost.
I'm registering this idea here so as to establish this as prior art. Any
other places I should register my idea?
The idea of piggy-backing on existing exit-sign-infrastructure strikes
me as very imaginative .. brilliant, even! :-)
Now, however, I have a practical question. The repeaters are not exactly
intended to be daisy-chained. From the (nice) docs page at netequality,
<quote>
If you only have a single internet connection feeding your mesh network,
it is desirable to have the Gateway be as central to the project as
possible. The reason for this is that for each Repeater you pass through
to get to the Gateway the maximimum speed is cut roughly in half.
</quote>
So I would imagine that is a serious limitation. What say you?
Regards,
..jim
I have thought about this because I use WDS through 3rd party firmware
on Linksys WRT54G routers (DD-WRT). The docs say that under WDS each
"hop" through the next incremental router cuts bandwidth by half. I'm
thinking one approach (I haven't tried it yet) would be using one
central wireless router as the contact point for all the other wireless
routers then any given wireless router would only have one hop through
the main router to the wired network. The practical setup would be to
designate in each wireless router ONLY the central router as a WDS peer
and in the central wireless router designate all of the other routers as
WDS peers. The main router still has a big load but each satellite
device doesn't suffer more than one "halving" (I'm sure there is a
semi-simple equation to represent the difference).
Now of course you still have the signal strength through building
material issues but I can think of several tricks to marginalize that
problem and in essence this is a separate issue. Concerning this
particular problem (Exit sign usage) I would also consider daisy
chaining the routers with both POE (power over Ethernet) and EOP
(Ethernet over power) so that the wireless connection is limited to the
closest wireless router to the wireless devices.
rbw
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