Tech companies have been trying to work around this problem by creating devices that can detect rival signals in the area and automatically shut down when they begin interfering with licensed spectrum already in use. Thus, for instance, a Bluetooth handset operating unlicensed on white spaces might flip off automatically if it came close to a working television. However, there has been a growing realization among white-space device-use proponents that adding sensing abilities to devices by itself won't cut it, because the FCC's tests found that device-sensing capabilities were poor at detecting such devices as wireless microphones that also use unlicensed frequencies.
Motorola has started working on a solution to this problem, testing out its geo-location database to help provide protection for existing broadcast signals. Essentially, geo-location tracks mobile devices by locating them through their specific IP address, media-access-control address, radio-frequency identification or other location-based information. From there, the database looks at the licensed spectrums being used within a given area, and ranks the remaining available spectrums by their strength and closeness to a spectrum already in use. Finally, the database automatically selects the optimal white-space spectrum for the device based on its location, then switches the device to a different spectrum once it moves to a different location.
Motorola concedes that these geo-location capabilities might not assuage the NAB, which has stated clearly that it wants no mobile devices operating on unlicensed television spectrum. However, the company is optimistic that the FCC soon will allow their devices to operate on the spectrum and will find that geo-location practically eliminates the risk of interference.
The road ahead
Although no one knows for certain how the FCC eventually will rule, both sides have been gearing up their public relations machines to make their case. Device-manufacturers Motorola and Philips have gone to the press to stoke expectations for how well their products performed in the FCC tests, while Verizon has tried to temper public expectations by indicating that more work would have to be done before it could come out in favor of white-space use.
The NAB, for its part, has created a campaign called "Interference Zones" that urges people to tell Congress to ban the use of unlicensed devices on white spaces. The association is illustrating this point by displaying a cartoon of a sinister-looking cell phone named Wally that gleefully interferes with Direct TV signals. Google, which so far has been one of the most vocal proponents of white-space use, launched its Free the Airwaves campaign this week to explain the white-spaces debate to the general public in layman's terms. "You don't need to be a telecommunications expert to understand that freeing the 'white spaces' has the potential to transform wireless Internet as we know it," says Minnie Ingersoll, the product manager for Google's Alternative Access Team. "There's no doubt that if these airwaves are opened up to unlicensed use, more people will be using the Internet."
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