The White Open Spaces

Thursday, August 16, 2007

COVETED BITS of the radio spectrum called "white spaces" -- unused areas of spectrum wedged between licensed TV channels -- may soon be freed up by the Federal Communications Commission. Right now no broadband devices are allowed to use these parts of the spectrum, but the FCC is considering whether to let companies sell FCC-certified wireless devices that would be used without an exclusive broadcast license in these slivers of bandwidth. Such white-space devices (WSDs) would be low-power and so would emit signals over very small geographic areas.

White space within the TV band is unlicensed, like WiFi, but is physically better suited than WiFi for broadband transmission. Given the innovation that WiFi access has spurred, as well as the potential for broader coverage both in rural areas and in urban community wireless networks (such as the free WiFi network in Dupont Circle), the FCC has already decided to allow WSDs that are fixed in one location starting after TV's digital transition in 2009. The more controversial issue the commission is considering is whether to also allow portable WSDs, which could be used in products such as laptops or personal digital assistants. Portable WSDs are more difficult to design because they'd need to instantaneously identify which channels are being used in different regions.

To test the feasibility of such devices, last year the FCC started soliciting designs for devices that can identify unoccupied channels and then transmit wireless signals that don't interfere with licensed broadcasts. Two prototypes, submitted by Microsoft and Philips, recently failed to meet the proposed sensing and non-interference requirements, the FCC says. Microsoft is disputing the test results for its prototype.

Broadcast companies (including those owned by The Washington Post Co.), afraid of potential interference from WSDs, are lobbying against use of white space. Groups such as the Association for Maximum Service Television have argued that the FCC should never allow portable WSDs because the failure of these recent prototypes proves no portable WSD technology could work without destroying TV as we know it.

Certainly the FCC shouldn't approve WSDs that will obliterate TV. But just because these prototypes fell short doesn't mean the technology can never work. The limited success of these devices and another designed at the University of Kansas certainly gives hope that someday a non-interfering product could exist. After all, low-power wireless microphone operators often already use white spaces for similar short-distance broadcasts without a license -- although they're supposed to get licenses -- and they coexist peacefully with TV stations. (Wireless microphone operators also oppose sharing white spaces with unlicensed Internet service providers.)

Given the good that could come out of using this unoccupied bandwidth, the FCC should continue to encourage WSD research and development.


© 2007 The Washington Post Company