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Message from discussion Relay-Stations for desaster regions
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sonicviz  
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 More options Apr 5 2011, 12:17 am
From: sonicviz <sonic...@gmail.com>
Date: Mon, 4 Apr 2011 21:17:54 -0700 (PDT)
Local: Tues, Apr 5 2011 12:17 am
Subject: Re: Relay-Stations for desaster regions
Today: Telecoms networks back / 90% of cell phone base stations, land
lines restored in disaster-hit areas
http://www.yomiuri.co.jp/dy/business/T110404003785.htm

Not bad, in just over 3 weeks...

On Apr 4, 6:14 pm, Torsten Wagner <torsten.wag...@gmail.com> wrote:

> Dear All,

> I talked to a group of amateur radio guys as I said in some posts ago.
> My idea was if there is a way to establish a bridge like
> WLAN/Ethernet ----- ham (packet) radio ----- Ethernet. They conclusion
> was that it might be technically possible. However, the speed achieved
> over packet radio on longer distances is rather low. Taking into
> account that many people on e.g., a shelter side try to access
> simultaneously, this could be a real bottleneck and finally people
> would run into "server timeouts".
> The other problem is that there are very different radio regulation in
> different countries, including different radio-frequencies for packet
> radio. Some countries require that only people with an amateur radio
> licences are allow to operate a packet radio station, others might
> require special licences, etc. I wasn't able to figure out the
> regulations in Japan. However, taking Japanese habits into account, I
> would assume it require some licensing and it might be rather strict.
> If we think a bit into the future. What might work now, might not work
> elsewhere in the world and vice versa.

> The final conclusion was to jump back to wifi. With a good focused
> antenna set-up, some dozen of kilometres can be covered. However, it
> would require "optical" visibility of both stations. Which means in
> principle a straight line between both stations without buildings,
> trees, mountains, etc. in between. On the other hand, the focused
> antennas help to avoid any conflict with other wifi spots (remember
> the number of channels is very limited for wifi).
> This would need an high antenna set-up either on top of an building or
> on some kind of (extension) mast (which might be problematic with
> aftershocks).

> I thought about a box mounted on a pushcart (remember they might need
> to be installed on a roof and lifts might not work) containing 2-4 car
> batteries, a very light extension mast (e.g. a fiberglas fishing rod,
> but don't know whether this is stiff enough for a directional wifi
> antenna), power converters (would only need DC since the wifiboxes use
> DC only) one modified wifi station which would act as an bridge taking
> signals from ethernet/wifi to send it over the directional antenna,
> additional wifi boxes which could be installed a bit away from the
> main station to enable good wifi connection. Cables to provide power
> and Ethernet to those satellite wifi-boxes.
> The idea with the satellite wifi boxes is due to the fact that the
> main station might need to stand on a rather "stupid" place to get a
> link with the other base station. Those satellite wifi boxes could
> bring the signal down into halls and other designated places. An
> additional solar panel might be useful to stretch battery life time.
> Another thought is to create only one kind of station which could
> easily without much effort act as either wifi-hotspot/bridge, repeater
> or bridge/gateway station.
> This redundancy might require more electronics, but would make the
> system completely interchangeable and provide easily extensible and
> much less maintenances at the final end.
> Finally the systems should be maintainable from the web to allow
> people to check for it without being physically available (not only
> the internet part but also battery status, etc.)

> Such a system could be easily transported and installed with an
> minimum of effort. People in shelters I saw carried around plenty
> laptops (people seems to leaving everything behind in their office but
> taking
> there laptops ;) ), smartphones, etc. They all could start
> communication with friends and family as well as get information over
> the web with such an system.

> I got contact details for a small company specialized in directional
> wifi bridging. Guess more ideas will follow from discussion there.

> Maybe all this is some stuff for thoughts and if needed I could add
> some of the stuff to the wiki

> All the best

> Totti


 
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