Spectrum Wars
The debate in San Francisco over whether to use unlicensed wireless or fiber underscores a growing problem for wireless systems: Can unlicensed spectrum deliver enough bandwidth? And not just for today. As increases in speeds from cable and telephone providers keep raising the bar, how can the ever more crowded slivers of unlicensed spectrum keep up?
This article originally appeared in the June 2007 issue of MuniWireless Magazine.
By Harold Feld
Special Interests Vs. Next-Generation Wireless
The debate in San Francisco over whether to use unlicensed wireless or fiber underscores a growing problem for wireless systems: Can unlicensed spectrum deliver enough bandwidth? And not just for today. As increases in speeds from cable and telephone providers keep raising the bar, how can the ever more crowded slivers of unlicensed spectrum keep up?
The FCC has before it a proceeding that can create the next generation of unlicensed wireless devices. Known popularly as the “broadcast white spaces proceeding,” the proposed rules would allow operation on the vacant channels on the television dial after completion of the transition to digital television (DTV).
Because DTV contains a “pilot signal” to boost reception by digital television receivers, unlicensed devices can avoid interfering with anyone watching television by sensing the signal and avoiding the “occupied” channels. Tech companies delivered a prototype to the FCC last March. If the technology proves reliable, it could open up broadcast spectrum for unlicensed use as early as February 2009.
In addition to providing more spectrum, the physical qualities of the broadcast white spaces make them particularly valuable for wireless broadband. Signals travel further, using less power, than in the higher bands. Signals in the broadcast bands can penetrate foliage and solid objects, making it easier and more cost efficient to construct networks. While these white spaces are primarily thought of as a boost to rural wireless systems, a study by the New America Foundation shows that even cities in the most crowded television markets will benefit.
Since it was initially proposed by the FCC in 2004, the proposal has run into fierce resistance from television broadcasters. Although broadcasters receive their licenses to use the public airwaves for free (unlike others that must pay for licenses at auction), they regard even the unused white spaces as “their” spectrum. Manufacturers of wireless microphones, who have special exclusive rights to use the broadcast bands and who would face competition from unlicensed devices, have also fought hard at the FCC and on Capitol Hill to muster opposition to the proposal.
Lobbyists for these companies have bombarded members of Congress and FCC Commissioners with doomsday scenarios. They argue that a flood of unlicensed devices would cause static on every television and make the Super Bowl and other events that rely on wireless microphones impossible. Broadcasters even circulated a DVD called “Your Neighbors’ Static,” which showed a little old lady unable to watch her new digital television because of her neighbor’s white spaces device. Wisely, the FCC decided to rely on its own engineering studies and moved to the pending proceeding in the fall of 2006.
Unable to stop the proposal from going forward, opponents of unlicensed devices in the broadcast white spaces have focused on including various “poison pill” conditions. Broadcasters persuaded the FCC also to consider whether to license the white spaces and sell the white space licenses at auction. Broadcasters have lobbied to prohibit operation of devices on vacant “adjacent” channels (i.e., vacant channels next to active television channels) as a precaution against interference even if testing shows there is no danger to television reception. These and other proposals have nothing to do with engineering reality, but everything to do with broadcasters working to keep other wireless users out of “their” spectrum.
Broadcasters and wireless microphone manufacturers have powerful lobbies. Despite the efforts of tech companies and public interest advocates to keep the FCC focused on engineering, the broadcasters continue to try to use political pressure to kill the prospect of opening the broadcast white spaces to unlicensed devices.
Those interested in seeing valuable new spectrum become available for the next generation of muniwireless networks would do well to make it clear to their members of Congress and the FCC that it should base the rules for unlicensed use in the white spaces on engineering, not special interest politics. With America continuing to fall further behind in international broadband rankings, we need to maximize the spectrum available rather than close off valuable channels to appease a powerful lobby.
Related posts:
Loading ...
