Microsoft, Google and several of the world's largest and most influential technology companies have found a way to provide wireless Internet access that's so fast it makes today's Wi-Fi networks seem as sluggish as dial-up service. Trouble is, this blazing-fast network access may hamper television signals when they go digital next year. Such is the dilemma of so-called "white spaces," the chunks of unused bandwidth layered between TV channels that are designed to keep broadcast signals from interfering with one another.

Tech companies say that using these unclaimed radio-frequency waves on the electromagnetic spectrum would allow computers, cell phones and other wireless devices to transfer data in gigabits per second (compared with Wi-Fi's megabit-per-second speeds), thereby supporting mesh networks, broadband access in remote areas and wireless hot spots. But before they can use it, they must get permission from the Federal Communications Commission (FCC), which wants proof they can efficiently pinpoint and use these white spaces without disrupting broadcast signals or other devices (such as wireless microphones) that already rely on these open frequencies.

Five companies—Adaptrum, Inc., Microsoft, Motorola, Philips Electronics and Singapore's Institute for Infocomm Research—are developing technologies that can effectively find these untapped frequencies and have submitted prototypes to the FCC. Each of the devices seeking to pass muster operates in a slightly different way (of which the agency would not provide any details), but all have the same goal: to identify a slice of pristine airwaves where a wireless device could operate without blocking other signals. So far, none of them have received approval.

The latest blow came late last month, when Microsoft acknowledged that its device for sensing white spaces "unexpectedly shut down" during testing, a spokeswoman for the company says, without providing additional detail, adding, "because of the shutdown, the FCC could not move forward with testing and made a decision to stop testing on this device." This was the second time in two months that a Microsoft device failed to endure FCC scrutiny.

Philips, a maker of digital-TV receivers as well as cognitive radio technology used to locate and link to any locally available unused radio spectrum, has an interest in seeing both technologies flourish. The company says its initial cognitive radio prototypes tested by the FCC successfully detected the presence of digital and analog TV signals as well as wireless microphone signals. Although these prototypes did not have transmitters, Philips plans to send a more advanced version to the FCC that can detect signals as well as transmit over the white spaces it finds, says Kiran Challapali, a project leader in Philips Research North America's wireless communications and networking (WiCAN) department.

The potential of sharing the public airwaves makes media companies jittery, particularly given the timing: television broadcasts are set to transition from analog to digital on Feb. 17, 2009. They do not want to invest in a digital infrastructure only to have cell phone and Internet traffic infringe on their channels, essentially making digital TV no more reliable than the analog sets that depended on tin-foil wrapped rabbit-ear antennas.

White spaces exist in-between analog signals, but because digital TV signals are more compressed and take up less space, there is expected to be more unused spectrum, some of which the FCC already auctioned off at the 700 megahertz band.

Ironically, Google (which has challenged and, in some cases, surpassed, Microsoft's supremacy as a provider of computer desktop software) has proved to be a powerful ally in this case. Last month it filed a petition with the FCC stating its support for spectrum-sensing technology—such as that proposed by its rival Microsoft. Its interest in wireless technology stems from the company's desire to promote its open-source Android operating system and software for mobile devices, which the company hopes will be available by this fall.

The tech firms argue that opening up the broadcast spectrum to wireless devices "would be akin to a faster, longer range, higher data rate Wi-Fi service," said Rick Whitt, Google's Washington, D.C., telecom and media lawyer, during a recent press conference held to promote the effort. "You may want to call it Wi-Fi 2.0 or Wi-Fi on steroids."

Ultimately, the tech market's goal is to sell mobile phones and computers that can find white spaces on their own and temporarily use them without the need to obtain licenses. Google, Whitt said, is hoping to put these types of devices in consumers' hands by the holiday season of late 2009.