The FCC's Office of Engineering Technology (OET) last week released a report stating low-power, unlicensed white-space devices with geolocation and sensing technologies could be used—with some conditions—without interference to existing surrounding users such as television broadcasters and wireless microphones.

At the same time, FCC Chairman Kevin Martin said he was going to circulate to his fellow commissioners the OET report that defines the standards that devices looking to operate in the white spaces must meet to avoid interference with broadcasters. He's seeking a vote on the idea at the FCC's Nov. 4 meeting.

Though the OET stated geolocation and sensing technologies would be adequate to avoid interference, it said devices with sensing-only technology would have to undergo another round of testing within the FCC labs.

Companies like Google, Microsoft and HP have argued for unlicensed use of the white-spaces--the unused slivers of spectrum in the 700 MHz band between spectrum used by broadcast TV stations. Broadcasters and wireless microphone users such as major sports leagues and entertainers have opposed the idea, saying unlicensed white-space devices will create too much interference. They have called on the FCC to allow a comment period on the engineering report before the commission votes on whether to allow white spaces use.

And it’s with good reason. The executive summary of the OET’s report is much more upbeat about the potential for white spaces than the entire 149-page document. Wireless microphone manufacturer Shure Inc., brings up a number questions about the report in a filing with the FCC. For instance, Shure points out that the OET barely mentioned highly publicized test data from FedEx Field—where the NFL’s Washington Redskins play—and another location in the D.C. area.

Further, TheWall Street Journal reported in August that a prototype designed by Philips Electronics North America was too sensitive during field tests at FedEx Field. The device indicated that every TV channel at the stadium was in use, which wasn't the case. That’s a big problem because the prototype was supposed to accurately detect signals that are in use in order to avoid interference. According to the article, representatives from the NFL, ESPN and wireless-microphone manufacturer Shure, watched the FCC engineers with shaking heads.

Is the FCC taking a big gamble if its proceeds with a rulemaking for white-space devices Nov. 4? Perhaps. But recall that the commission’s gamble on unlicensed spectrum worked in 1985, when the agency set aside unlicensed spectrum for devices that hadn't been invented yet. It did so despite fear that using those airwaves would interfere severely with microwave ovens and baby monitors. A few years later, Wi-Fi was born and proliferated.

However, the FCC also took a gamble with broadband over power line technology, with an opposite effect. BPL, which involves broadband signals being carried by either fiber-optic or telephone lines and injected into the power grid onto medium-voltage wires, was heavily championed by the FCC back in 2003. At the time, amateur radio users, along with governmental stakeholders and broadcasters, voiced their concerns about interference.

The FCC moved ahead after testing and was sued by the American Radio Relay League (ARRL), which represents amateur radio users, for not fully disclosing for public comment the studies the FCC used in its BPL rulemaking. Earlier this year, a D.C. district court agreed with ARRL, effectively halting the expansion of BPL until the FCC can come up with more facts supporting its conclusion that the technology doesn't cause interference. We could very well see similar lawsuits come from broadcasters regarding white spaces use, as the precedent has been set.

Not only are broadcasters at risk of interference but so are public-safety users. John Powell, senior consulting engineer for the National Public Safety Telecommunications Council, recently told Urgent Communications that white-space devices, while perhaps detecting the presence of high-power television signals, may not be able to detect lower-power public-safety communications in Channels 14-20 and the upper end of the 700 MHz band. In particular, surveillance equipment used by public safety on these frequencies is specifically designed not to be detectable. And geographic restrictions are not adequate safeguards, even for fixed devices, he said.

Given the FCC’s apparent enthusiasm for moving ahead with white-space devices and an engineering report that seems less than straight-forward, it’s imperative that the public-safety community become more vocal regarding the potential for interference to its life-saving communications systems.