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See Inside June 2008

Microsoft, Google Fighting for Unused Spectrum between TV Channels

Could future wireless devices destroy HDTV broadcasts?

Microsoft, Google and several more of the world’s largest and most influential technology companies have found a way to provide wireless Internet access that is so fast it makes today’s Wi-Fi networks seem as sluggish as dial-up service. The prospect, however, has big media broadcasters up in arms, because this blazing-fast network access may hamper television signals when they go digital next year. In a test conducted last year by the Federal Communications Commission, wireless devices blanked out digital programming on nearby television sets.

At the heart of the dilemma are 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. These spaces will get even bigger on February 17, 2009, the legally mandated day for TV broadcasts to go completely digital, freeing up more of the airwaves. (Digital signals take up less airwave space than their analog counterparts.)

Tech companies see huge opportunities in these radio-frequency buffer zones. The slices could allow computers, cell phones and other wireless devices to transfer gigabits of data per second (compared with Wi-Fi’s megabit-per-second speeds), thereby supporting mesh networks, broadband access in remote areas and wireless hot­spots. “You may want to call it Wi-Fi 2.0 or Wi-Fi on steroids,” said Rick Whitt, Google’s Washington, D.C., telecom and media lawyer, during a recent press conference held to promote the effort. In March, Google filed a petition with the FCC stating its support for white-space-sensing technology—such as that proposed by rival Microsoft. Google’s interest in wireless technology stems from the company’s desire to promote its open-source Android operating system and software for mobile devices, which Google hopes will be available by this fall.

But broadcasters 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 tinfoil-wrapped rabbit-ear antennas. So before Google and the others can exploit white spaces, they must get permission from the FCC, which wants proof that they can efficiently pinpoint and use them without disrupting broadcast signals or other devices (such as wireless microphones) that already rely on these open frequencies. Five companies—Adaptrum, Microsoft, Motorola, Philips Electronics and Singapore’s Institute for Infocomm Research—have submitted prototypes to the FCC. Each of the devices—which represent a form of so-called cognitive radio—tries to identify a slice of pristine airwave space wherein a wireless device could operate without blocking other signals.

So far none of them have received approval. Although some of the prototypes can detect the presence of TV and wireless microphone signals, the ones that have transmission capability have yet to demonstrate reliable function. A recent blow came in late March, when Microsoft acknowledged that its device for sensing white spaces “unexpectedly shut down” during testing; a spokesperson for the company adds, without providing additional detail, that “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.

Tech firms believe they will ultimately succeed in devising a technology that can find white spaces on its own and temporarily tap into them without interfering with licensed users. Philips, for instance, plans to send a more advanced version of its spectrum-sensing technology to the FCC soon that can detect signals as well as transmit them without interference, says Kiran Challapali, a project leader in Philips Research North America’s wireless communications and networking department. If such systems pass muster, Whitt said, Google would try to put a new crop of wireless devices that could make use of white spaces in consumers’ hands by the holiday season of late 2009—without fear of blanking out your pricey big-screen HDTV set.

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