The Federal Communications Commission today unanimously approved new rules for the use of unlicensed white space spectrum in a move that could pave the way for more unused wireless spectrum to be released in the future.
White space is unused spectrum that sits between TV channels. The 300MHz to 400MHz of unused spectrum is considered prime spectrum for offering wireless broadband services because it can travel long distances and penetrate through walls. The FCC unanimously agreed in November 2008 to open up this spectrum for unlicensed use. Even so, technical issues to allow device makers and service providers to use the spectrum still need to be worked out.
The latest vote to approve the use of white spaces now paves the way for service providers and device makers to begin designing products that take advantage of the spectrum. Companies like Google, Microsoft, Dell, Motorola, and Hewlett-Packard have lobbied for years to get this spectrum open for public use.
The roll out of TV white space spectrum might also serve as a template for freeing other underutilized spectrum.
"About 90 percent of the licensed spectrum is unused," said Joe Hamilla, chief operating officer at Spectrum Bridge, a company that runs an online spectrum license exchange. "What's happening with TV white space is really the FCC's first attempt at trying to make more efficient use of underused spectrum."
As part of the new rules adopted today, the FCC agreed to set aside two channels for wireless microphone use to mitigate potential interference issues. But the commission said it would not require device makers to include geolocation spectrum sensing technology in new devices to ensure that these products don't interfere with existing services already using the spectrum. This is a key win for device makers, because it means that they do not have to include the potentially expensive technology in their products.
Instead, devices will query a special geolocation database that makes sure no one is using that spectrum before it transmits. This database check is largely to prevent white space services from interfering with broadcast TV signals.
The FCC's Office of Engineering and Technology will get the database up and running. It will also select companies that will manage the database going forward. Companies, such as Google and Spectrum Bridge, have submitted proposals for managing the database.
FCC Chairman Julius Genachowski has called the new wireless broadband services that could eventually operate over this spectrum "Wi-Fi on steroids." Wi-Fi uses unlicensed spectrum that was opened up by the FCC in 1985, which was the last time the FCC allocated unlicensed spectrum. This high-frequency spectrum was originally used for cordless phones and garage door openers, but the spectrum later found broader use in high speed, in-home Internet connectivity via Wi-Fi.
The main difference between the white space spectrum and the spectrum used for Wi-Fi is that white spaces are at a lower frequency, which means they travel much longer distances and penetrate obstacles, such as walls, much more easily than higher frequency spectrum used for Wi-Fi.
Chairman Genachowski is optimistic that the new unlicensed spectrum will help create a robust ecosystem, such as the one that has developed around Wi-Fi.
"This new unlicensed spectrum will be a powerful platform for innovation," Genachowski said. "When we unleash American ingenuity, great things happen."
The FCC has said previously that the nation is facing a looming spectrum crisis, and if more spectrum is not made available in the next few years, there won't be enough airwaves to keep up with growing wireless data demand. The agency has made opening up new wireless spectrum a top priority. In its National Broadband Plan, it said it would free up 500MHz of new wireless spectrum within 10 years for licensed and unlicensed use. The plan recommends that 300MHz of that spectrum should become available within the next five years.
White space spectrum is part of this plan. The FCC is also looking to reclaim or share spectrum from government agencies that are under-using their spectrum.
Hamilla said the same techniques used for mitigating interference in unlicensed TV white space spectrum bands could be used in other wireless bands as well. For example, he believes a database could be used to allow public safety officials and commercial users to share spectrum in the D block of the 700MHz band. This spectrum was not auctioned off when the original auction occurred in 2008, because it didn't meet the necessary requirements. The government has been deciding what to do with the spectrum ever since.
"The database could instruct radios to vacate the channels when there is an emergency, such as a fire, earthquake or hurricane, so that public safety officials could get priority," he said. "But when there isn't an emergency, that spectrum is unused and it could be used for commercial use."
If and when the FCC decides to open new spectrum using these methods, it will have to go through another procedural process to get comments to open the spectrum. But Hamilla hopes that the next time the FCC tries to do this, it won't take as long. The procedure to open the TV white spaces began in 2002 under then-FCC Chairman Michael Powell.