Most broadcast channels are separated by small swaths of spectrum, or unused channels called, which limit interference from other stations. Technology companies and consumer advocates believe the use of this unlicensed spectrum could open up a wireless broadband pipe into the home, providing a competitor to cable and DSL services.
Technology companies in particular say that using the spectrum between the TV channels could unleash a wave of innovation. These companies, which include Microsoft, Intel, Google, EarthLink and Dell, have joined forces. Calling themselves the White Space Coalition, they've been lobbying the FCC and Congress to open up this spectrum.
Not surprisingly, TV broadcasters oppose allowing any unlicensed device to use white-space spectrum because, they argue, these devices would interfere with television broadcasts, potentially harming the federally mandated transition from analog to digital TV service.
"There are serious interference issues with unlicensed devices," said Dennis Wharton, spokesman for the National Association of Broadcasters. "Our suggestion to the FCC is, let's get through the analog transition to digital TV before we suggest introducing unlicensed devices onto airwaves that could cause disruption to millions of TV viewers."
Congress has mandated the airwaves in the 700MHz band be vacated in February 2009,as part of the long-anticipated switch to all-digital television. are eager to get their hands on the spectrum because of its inherent physical properties, which allow signals to travel farther and more easily penetrate walls.
Countering Wharton's argument, the White Space Coalition says that it can design devices that don't interfere. And it submitted prototypes to be tested by the FCC earlier this spring.
Testing of these devices has recently been completed with mixed results. On July 31, the saying that a testing prototype developed by Microsoft failed to detect digital TV signals in order to avoid them in tests designed by the commission. But another device, made by Koninklijke Philips Electronics, was able to detect broadcast signals, according to the commission's report.
Microsoft is now saying that the results of the FCC test are invalid. In a letter it filed this week with the FCC, Microsoft said the device the FCC tested was defective. And another model of the same device worked successfully in a demonstration it gave to the FCC last week, according to the letter.
"We don't think anything the commission did in its testing in any way diminishes the potentiality of white-space devices," said Ed Thomas, former chief engineer at the FCC and now technology policy adviser and partner at Harris Wiltshire & Grannis, the firm representing the White Space Coalition. "We still believe that the white spaces could be used without causing harm to broadcasters. And we want to work with the commission to product the services of incumbent licensees."
What is white space and why should I care?
The FCC has had an open proceeding on the possibility of using this spectrum since 2002, but it still hasn't taken any action. The FCC's office of engineering and technology plans to hold an open meeting Thursday to discuss testing options for new white-space devices.