Microsoft’s White Space Solution for Rural Wireless

By Andrew Gauthier 


Last week, at a communications conference in Barcelona, Spain, researchers from Microsoft and Harvard University unveiled a detailed report suggesting an exciting solution for the unused portions of wireless spectrum sitting between TV channels, commonly referred to as “white spaces.”

The debate over white space has gone on since tech companies and wireless providers began to compete for the FCC’s limited frequency allotments. Tech companies like Google have lobbied Congress for years to open this spectrum for unlicensed use. Since large portions of the spectrum operate at lower frequencies, it can travel longer distances than the unlicensed frequencies typically used for Wi-Fi devices–good news for rural areas.

“Imagine the potential if you could connect to your home [Internet] router from up to a mile,” says Ranveer Chandra, one of the author’s of the report.

In November 2008, the FCC ruled to allow the unlicensed use of white space, but issued a strict set of guidelines to prevent interference between wireless devices and existing TV broadcasters, or other devices using the same spectrum, such as wireless microphones.

TV broadcasters have long opposed the use of this spectrum (initially meant as a buffer between stations’ frequencies), saying it will interfere with their services. Devices like wireless mics can suddenly become active without warning, and even minor transmission can cause audible interference. In order to adhere to the FCC guidelines for white space use, the challenge facing developers was to find a way to predict which part of the spectrum a TV broadcast or wireless microphone is using at any given time.

Microsoft’s White-Fi algorithm enables a wireless device to find its “best use” frequency, by measuring the spectrum conditions around it, finding available frequencies, and searching for interference. If any is detected, the device will shift to a different sliver of spectrum. As television continues the transition from analog to digital, more and more spectrum will become available, making this “best use” process even easier.

Some would cast the debate as the latest battle in the bitter war between new media and old. But as the number of viewers who watch TV programming online grows, it seems more likely that both new and old media stand to benefit from this development. Better internet will help accrue revenue for tech providers, and eyeballs for broadcasters.