This scene appears so commonplace, there seems nothing to notice: a student waiting for a rapid transit car, connecting to the Internet with her tablet. You might miss an oddly shaped antenna on the roof.
The scene is a station on West Virginia University's elevated "personal rapid transit" or PRT system, where on a recent December afternoon, 21-year-old Gail Jennings is waiting for the next car. The senior accounting major pulls a Dell Venue Pro 8 running Windows 8 from her shoulder bag, and surfs to a WVU website, SimpleGifts, for a streaming video of the annual holiday concert. Her web connection, and the streaming video, are fast and smooth, via a Wi-Fi connection to an access point in the transit station.
But it's what the access point is attached to that makes this scene uncommon: a "white spaces" radio that is part of a campus pilot network turning unused TV frequencies into a broadband cornucopia of new spectrum for fixed and mobile users. Like the efficient 30-year-old PRT system, WVU's 7-month-old white spaces network links three main campus locations, ranging from a mile to a mile and a half from each other over the hills and dales of Morgantown.
"Broadband in this state is a huge challenge," says John Campbell, WVU's chief information officer. "We're very rural and very mountainous. Between the terrain and the weather, it's hard on infrastructure."
Campbell was approached two years ago by Air.U, a consortium of education associations, public interest groups and tech companies, including Microsoft and Google, working to bring white spaces networks off the drawing board into production. "We immediately jumped at the chance, not just for around the campus, but around the state," Campbell says.
The white spaces bonanza
"White space" refers to two types of spectrum traditionally set aside for TV broadcasting: the unused spectrum deliberately left between different TV channels, acting as a buffer between them; and unused spectrum that was either left over or vacated as TV stations shifted from analog to digital TV.
In 2008, the FCC leveraged both types, ruling that unlicensed, unused VHF and UHF TV channels could be used for other applications, with certain restrictions and requirements. In the U.S., these TV bands are 6-megahertz channels mainly in the 470-698 MHz UHF band.
Because of the lower frequencies, these signals propagate very well meaning they can penetrate walls, roofs and other obstacles. They also can reach much longer distances than Wi-Fi, and they can, in effect, "flow" over hills and valleys. At WVU, for example, the radio distances range at full power up to five miles.
WVU is using FCC-certified white space radios from Adaptrum, a San Jose startup that has developed a software-defined radio that can dynamically shift channels, channel sizes, and power levels. The company says its radios are highly efficient. "We use 90% to 95% of each 6 MHz TV channel, about 2 bits/hertz, which is about the maximum, for 12 to 14 megabits per second per TV Channel," says Darrin Mylet, Adaptrum's head of business operations and regulatory affairs. "We can use 12 high-powered channels in West Virginia. Twelve [channels] times 14 [MBps] bring you into the hundreds of megabits per each small cell."
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