Motorola's early tests show that there's still work to be done. During an FCC trial in October, Motorola's device, which is about the size of a suitcase and can currently only receive signals, was able to find some but not all of the allocated frequencies in its vicinity. "These aren't ready to go," admits Sharkey. "They are more developmental devices, and the idea of the test is to demonstrate the basic technologies and help the FCC understand all the interactions [between transmissions]."

While eventually it may be possible to shrink down a white-space radio to the size of a cell phone, Sharkey says that Motorola is more focused on bypassing wired Internet technology by providing broadband to rural areas and providing point-to-point wireless antennas.

Other companies are more reticent to talk about their white-space plans, but Jake Ward, spokesperson for the Wireless Innovation Alliance, a consortium of companies that helped convince the FCC to open up white spaces, says that these companies have a wide range of motives. For example, computer manufacturers such as Dell may want to build broadband wireless Internet cards that are faster and have more range than existing ones do. Software companies like Microsoft could be interested in building software and applications for new devices. And an Internet giant like Google may simply want to push Internet coverage to increase the number of people who see Google ads. "Each company has its own interests," Ward says, "but the underlying principle is that higher connectivity is better for everybody."

Ward describes one white-space application as "mind blowing": sending high-definition television signals from one room to another within a house. "You have a TiVo, a DVD player, a cable box, and three high-definition TVs," he says. "Using a white-space device, you could beam those signals anywhere, to any TV."

Of course, technical and policy challenges still remain. "Right now, a device capable of moving around to different frequencies at will is very expensive," notes UC Berkeley's Sahai. But he suspects that economies of scale will lead to affordable devices within the next couple of years. Additionally, he says, regulations need to be established to ensure that devices consistently avoid causing interference. Ultimately, however, Sahai sees no shortage of demand for the wireless spectrum. "If you build it better and faster and easy to deploy, then the applications will come," he says.