
Darpa begins work on 100Gbps wireless tech with 120-mile range - Libertatea
http://www.extremetech.com/computing/143455-darpa-begins-work-on-100gbps-wireless-tech-with-120-mile-range?utm_source=rss&utm_medium=rss&utm_campaign=darpa-begins-work-on-100gbps-wireless-tech-with-120-mile-range
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leoedin
The thing to remember with all geosynchronous satellite communication is
latency. It's terrible. By virtue of being 36,000 km away, you fundamentally
can't have a communication time of less than 1/4s. That's fine for moving
large numbers of bits (video transfer) but terrible for 2 way communication.
Without any other delays, it takes over 1/2 a second between sending a request
and seeing the result.

Perhaps the protocols they're developing will have use for ground level
civilian communications, but it's unlikely that satellite based internet will
ever see widespread adoption in the west because of latency.

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dnu
But why should the satellites be on geosynchronous orbit? What if we bring
them closer to Earth? For example, when we use mobile internet, we travel from
antenna to antenna. With satellites on lower orbits, the antennas will travel
around us.

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leoedin
This is possible, but the problem is that the closer your satellites get to
earth, the larger number of satellites you need in your constellation to
maintain coverage. Iridium[1] spent $6 billion putting a very large
constellation of satellites into orbit and promptly went bust. Convincing an
investor that you won't end up having the same problems that iridium had would
be tricky.

It's certainly not impossible, but I would be surprised if the economics of
satellite based internet can compete with fibre based networks. The areas
where fibre isn't feasible are also probably the areas with few people, and so
the potential to make money is limited.

Iridium has shown that (once you disregard capital costs), there is a niche
for satellite based telecom services, but it's a fairly niche area.

[1]: <http://en.wikipedia.org/wiki/Iridium_Communications_Inc>.

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dnu
Well, if it's DARPA, then probably the main purpose of the network will be
military. And I'm pretty sure that they have much more money than Iridium.

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leoedin
Obviously military use is quite different from civilian use. I was really
trying to address the part of the original article which suggested that this
technology might make its way into civil life.

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rjzzleep
is it just me, or do other people get bored by "begins work on" titles too?

first of all there's probably more than darpa working on it. second of all
darpa is not working on it(yet)? they want people to come in and help design
it for them. hence the link.

<http://www.darpa.mil/NewsEvents/Releases/2012/12/14.aspx>

but as always, please correct me if i'm wrong

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DasIch
Hum, is bandwidth really such an issue when it comes to UAVs? A video stream
will consume quite a bit of bandwidth granted but I'd imagine latency to be a
much more serious issue. Who cares whether you have a HD video stream if the
stream shows you what happened half a second ago?

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Symmetry
_"One day, you might even have a 100Gbps wireless link from your home to your
ISP."_

Probably not, there's far less spectrum reserved for civilian uses than for
military per capita.

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noselasd
Spectrum can be freed up for other uses, and people continuously make better
modulation techniques to make better use of the spectrum.

And there's already a lot of ISPs that provide point to point wireless links.
You get an antenna, hook it up outside your office building, point it at the
radio tower of the ISP.

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gerhardi
Wow.. this certainly sounds like a big leap, but I think that this will not
succeed during the next 10 years. This would allow an whole army of remotely
controlled drones with realtime sensor data and high definition video to
operate within a quite large area. How many UAV:s operating within the same
area can be nowadays handled simultaneously through one "command center"?

