The Future of White Space Still Up in the Air

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The nascent white space sector got a boost this week as the Federal Communications Commission said that it would test the database operated by Spectrum Bridge, according to a story in GigaOm.

White space spectrum is the term used to cover spectrum between television channels that is being opened up by their digitization and relocation to other parts of the spectrum. The company is one of 10 selected to perform the vital database function, which involves tracking what spectrum is in use at a specific time and place.

White space, which is comprised of spectrum with terrific reach and the ability to permeate structures, is fraught with almost as much challenge as it is laden with promise. It is, in essence, an accounting headache: Broadcast channel profile differs greatly between locales. There are many channels available in rural areas, while urban centers have less to offer. This must be tracked so that the "super Wi-Fi" doesn't interfere with broadcast televison or existing users of the spectrum such as wireless microphones.

The database requirements set by the FCC are designed to confront the challenge. Eventually, the databases will work with agile "coherent" radios to enable the white space infrastructure to take advantage of what is available and avoid channels that are occupied. The technology to do this, it should be noted, has application far beyond white space. It potentially is a major tool for the industry trying to stretch bandwidth in the face of unprecedented and rapidly growing demand.

It is also important to note that the Spectrum Bridge trial doesn't appear to test the full vision of agile radios. The FCC suggests this in its press release:

The limited trial is intended to allow the public to access and test Spectrum Bridge's database system to ensure that it correctly identifies channels that are available for unlicensed TV band devices, properly registers those facilities entitled to protection, and provides protection to authorized services and registered facilities as specified in the rules.

In other words, the hard part-actually changing the channel as the device is in use and conditions shift-is a test for another day.

That doesn't mean the trial isn't important. Just as drug trials start with testing potential dangers before actual effectiveness, the white space industry must crawl before it walks.

Even if the databases work, concerns on antenna height limitations and the possibility of auctions could impede white space. The current rules on how high antennas can be built must be changed or the reach of white space will be severely constrained, experts say. There also is talk that Congress may opt to auction off some of the spectrum that the white space industry covets.

Paula Bernier, writing at TMC.net, quotes attorney Stephen Coran, who said that potential legislation percolating in Congress bodes poorly for white space:

The problem, Coran explained today, is that such legislation talks about packing TV channels closer together. That means less white space between those channels. And while these efforts aren't active moves against white space, but rather aimed at making more spectrum available for incentive auctions that could provide the federal government with new funds, white space would nonetheless be "collateral damage," he said.

The bottom line is that while the Spectrum Bridge news is positive, it can fairly be said that the fate of white space still is up in the air, literally and figuratively.