White Spaces, Blacked Out: Empty airwaves called white spaces could enable long-range "Super Wi-Fi," but FCC rules strictly limit their use in populated areas. Such areas show up in black on this map of white-space availability in the part of the VHF band that corresponds to TV channels 7 to 13. A similar problem also occurs in the UHF spectrum.
Credit: Spectrum Bridge
Credit: Spectrum Bridge
A new model for managing America's airwaves was unveiled Monday, as part of a plan by Federal Communications Commission chairman Julius Genachowski to ease what he calls America's "spectrum crisis." As wireless devices proliferate, Genachowski has repeatedly said, the U.S. needs to free up more spectrum for modern uses.
Right now a giant swath of America's best airwaves is used mainly by local TV stations. The band is almost 300 megahertz wide—slightly more raw capacity than AT&T, Verizon, T-Mobile, and Sprint have, combined. The idea of Super Wi-Fi is to make use of the vacant airwaves that lie between existing TV stations' frequencies, gaps known as white spaces. However, other applications, such as wireless microphones, already have some rights to those frequencies. That is where an FCC-approved database, which was opened Monday for public testing, comes in. It will allow someone who, for example, wants to use a wireless microphone for a musical in Reno, Nevada, to register where he needs to use those airwaves. New Super Wi-Fi devices can access that database and make sure not to send out interfering signals. If he doesn't register, he can't be assured of having that spectrum free.
The new system is a significant advance over the old way of governing the nation's airwaves, says Jeff Schmidt, the director of engineering at Spectrum Bridge, which is overseeing the first white-space database. Right now large parts of the spectrum go to waste because the license holder who controls them has no incentive to let other people use them, even when it doesn't need them. "The old system was that [a company] got a chunk of spectrum and used it for its network," says Schmidt. "White spaces allow a bunch of dissimilar users to share spectrum efficiently."
Source: technologyreview.com
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