Questions still abound regarding white-space use
While all eyes were on the historic presidential election yesterday, the FCC was busy with some critical votes of its own.
It unanimously voted to approve the use of unlicensed white-space devices, but imposed restrictions to help avoid potential interference with TV signals and wireless microphones. The FCC reasoned that white-space devices will usher in the next Wi-Fi revolution.
White-space spectrum—the unused slivers in the 700 MHz band between the airwaves used by broadcast TV stations—has been the subject of heavy debate. High tech companies such as Google, Microsoft and Motorola have been pushing the FCC for its use. 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 it released last month that concluded white-space devices could operate in the spectrum using both geolocation and spectrum-sensing technologies to avoid interference.
More recently, members of the public-safety community weighed in on the debate. The Louisiana Governor’s Office of Homeland Security and Emergency Preparedness noted that broadcasters provide a vital emergency communications tool to the general public and urged the FCC to delay its vote to offer reasonable commentary on its technical report. Similar comments came from the Nebraska Emergency Management Agency.
Moreover, white-space devices may not be able to detect lower-power public-safety communications in Channels 14-20 and in 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.
The technical conditions the FCC imposed include requiring both fixed and portable devices to include geolocation and spectrum-sensing capabilities and use an FCC database that includes TV signals and the location of venues such as stadiums and concert arenas that use wireless microphones. These capabilities, said the FCC, would prevent interference and ensure compliance with commission rules. Geolocation technology maps the location of the device and compares it to the location of TV stations in an area.
The FCC also said devices that use only spectrum-sensing technology would be allowed, but only if they undergo additional certifications, including proof-of-performance tests. These tests would be made public and the public could comment on them. In the commission’s initial engineering tests, spectrum-sensing technology—which is supposed to determine whether spectrum is clear before transmitting a signal—didn’t pass with flying colors.
The commission said it would closely oversee and monitor the introduction of white-space devices and said it would act promptly to remove from the market any equipment found to be causing harmful interference. It also said it would require the responsible parties to take appropriate actions to remedy any interference that may occur.
It will be interesting whether the FCC’s move placates those opposed. The FCC, while enthusiastic for white-space devices, appears to be moving cautiously on the matter, but I question its power to prevent interference once a host of devices are out in the market. How can it effectively remove all equipment that is found to cause harmful interference to incumbents? One also has to wonder how easy it is to engineer commercial-grade white-space devices that incorporate geolocation and spectrum-sensing technology at a price point low enough to ensure their marketability.—Lynnette
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