Wi-Fi via White Spaces

[David Farber <dave () farber net>]

Begin forwarded message:

From: dewayne () warpspeed com (Dewayne Hendricks)
Date: August 18, 2009 1:40:29 PM EDT
To: Dewayne-Net Technology List <xyzzy () warpspeed com>
Subject: [Dewayne-Net] Wi-Fi via White Spaces

Tuesday, August 18, 2009
Wi-Fi via White Spaces
A network design that uses old TV spectrum could produce better long- 
range wireless connectivity.
By Erica Naone
<http://www.technologyreview.com/communications/23271/?a=f>
Long-range, low-cost wireless Internet could soon be delivered using  
radio spectrum once reserved for use by TV stations. The blueprints  
for a computer network that uses "white spaces," which are empty  
fragments of the spectrum scattered between used frequencies, will be  
presented today at ACM SIGCOMM 2009, a communications conference held  
in Barcelona, Spain.

TV stations have traditionally broadcast over lower frequencies that  
carry information longer distances. However, with the ongoing  
transition from analog to digital broadcasts, more unused frequencies  
are opening up than ever.

By tapping into these lower frequencies, it should be easier to  
provide broadband Internet access in rural areas and fill in gaps in  
city Wi-Fi networks. For example, the spectrum between 512 megahertz  
and 698 megahertz, which was originally allotted to analog TV channels  
from 21 to 51, offers a longer range than conventional Wi-Fi, which  
operates at 2.4 gigahertz. "Imagine the potential if you could connect  
to your home [Internet] router from up to a mile," says Ranveer  
Chandra, a member of the Networking Research Group at Microsoft  
Research behind the project.

The FCC ruled last November that companies could build devices that  
transmit over white spaces but also gave strict requirements that this  
should not interfere with existing broadcasts, both from TV stations  
and from other wireless devices that operate within the same spectrum.  
Chandra and his colleagues designed a set of protocols, which they  
call "White Fi," to successfully navigate the tricky regulatory and  
technical obstacles involved with using white spaces.

"It's a totally different paradigm for wireless networking," says  
Chandra. "Until now, in wireless networks, you were given a spectrum,  
and you would share it with everyone else. Everyone was an equal  
stakeholder. Now, you have this spectrum where there are certain  
people who are primary users."

One of the main obstacles for Chandra's group was dealing with a  
network of different devices; in the past, work focused on sending and  
receiving signals between individual devices over white spaces.

[snip]
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