In a move that proponents say will open the door to widespread mobile broadband adoption, the Federal Communications Commission Tuesday voted unanimously today to allow conditional unlicensed use of "white spaces" television spectrum.

As outlined recently by FCC Chairman Kevin Martin, the commission voted to let carriers and other vendors deploy devices in white space spectrum which operates unlicensed at powers of 100 milliwatts. His proposal would also permit use of white space on channels adjacent to existing television stations at powers of up to 40 milliwatts.

The debate over white spaces has been a contentious one, with tech companies such as Google and Microsoft pitted against all the major broadcasting companies, as well as major telecom carriers such as Verizon. Proponents of unlicensed white space use have often argued that opening up the spectrum would help bring mobile broadband to under-served regions and would help close the so-called "digital divide" between many urban and rural areas in the United States. On the other side, the National Association of Broadcasters (NAB) has argued that mobile Internet devices cannot operate on unlicensed spectrum without clashing with broadcasts on nearby frequencies.

The debate recently shifted in favor of unlicensed white spaces use, however, when the FCC released a report showing that wireless devices could avoid interfering with broadcasts by sensing when nearby licensed spectrum was in use and shutting down transmissions.

Martin said that as a precondition for allowing unlicensed white spaces use, all devices operating on the spectrum would have to have these sensing capabilities that would automatically shut the device down if it comes into interference with broadcast spectrum, as well as access to a geo-location database that tracks mobile devices by locating them through their specific IP address, media-access-control address, radio-frequency identification or other location-based information. Once the database has a fix on the device’s location, it can select the optimal white-space spectrum for the device and even switch the device to a different spectrum once it moves to a different location.

Unlicensed white space use proponents cheered the FCC’s decision today, calling it a major step forward toward bringing the United States up the speed with other nations’ mobile broadband capabilities.