Robert Fontana disappears into a hallway. Seconds later, a small reddish blob of pixels appears and moves around a field of blue and green on a computer monitor hooked up to a shoebox-sized device. The splotch tracks Fontana’s position in the building, even through the two walls between him and the technology he’s showing off: a tracking and collision avoidance system that can “see” through barriers like walls (or trees) and measure a target’s position, bearing and speed. Fontana, president of Germantown, MD-based Multispectral Solutions, says what’s inside his shoebox can one day help keep helicopters, cars and other vehicles from ramming into obstacles like power lines or people.Behind the device is a radio technology called ultrawideband that for decades was the province of military labs. But in the last few years, startups, information technology companies and consumer electronics giants have begun pushing ultrawideband beyond the radarlike systems the military pioneered and into applications that could transform the home. Sony and newcomer XtremeSpectrum in Vienna, VA, for instance, are both pursuing the possibility of using ultrawideband transmission to wirelessly link DVD players, stereos and TVs in home entertainment systems. In the future, ultrawideband links could distribute extremely information-rich content, endowing a home or office with high-resolution 3-D virtual-reality simulation. Ultrawideband can also zap data between computing devices up to 10 times faster than today’s rat’s nests of wired links.
Other potential applications include tracking objects and people to centimeter accuracy (even through walls) and ultrasensitive detectors for everything from home security systems to virtual pet enclosures. Ultrawideband tags could let robotic lawn mowers or vacuum cleaners go about their tasks without ever hitting a tree or a sofa. “We’ve got the most feasible technology for the George Jetson-like homes of the future,” says Bruce Watkins, president of Pulse-Link, an ultrawideband startup in San Diego.
Ultrawideband, proponents say, will deliver all of this via cheap, low-power radios. And, they contend-albeit over vigorous disagreement from skeptics-it won’t suffer from the interference problems that plague many existing wireless devices. “It’s a tremendous new technology,” says Geoffrey Anderson, vice president of Sony Electronics’ Advanced Wireless Technology Group. “Ultrawideband could really be a huge benefit to the consumer market.”
But the same qualities that enable such an array of applications also make ultrawideband divisive. In February, the Federal Communications Commission gave limited approval to the technology, opening the door to its commercialization, if only a crack. The FCC process generated almost 1,000 public comments-many more than most proposals elicit. And while much of the feedback was supportive, cell phone makers and service providers, Global Positioning System companies, satellite radio firms, airlines, and a slew of civilian and military government agencies all objected to the FCC’s plans to approve ultrawideband. Their beef: ultrawideband transmissions would interfere with the radio frequencies they rely on. These groups cited consequences ranging from the inconvenience of dropped cell phone calls to the frightening scenarios of foiled guidance systems preventing planes from landing in poor weather and wayward bombs that hit civilians. “The price of that interference is going to be very severe if a bomb is misdropped,” says Badri Younes, assistant secretary of defense and director of the U.S. Defense Department’s office of spectrum management.
For now, with few systems around for testing, discussions of ultrawideband’s promise and peril are largely theoretical. Although the FCC and other agencies have done some testing of the technology, the trials have mostly been conducted using lab devices-whose ultrawideband signals may be stronger, or weaker, or otherwise very different from those that will be produced by real-world devices.
With the new regulatory backing, companies will finally bring the technology to market over the next few years, and the practical answers needed to resolve the technical and political uncertainties about ultrawideband’s potential should emerge. Then we’ll see whether ultrawideband will transform the wireless world-or bring it crashing down.
Pulses of Power
Ultrawideband was born in the military labs of the 1960s. Looking for a way to let radar “see” through trees, researchers came up with the idea of using extremely short pulses of radio energy. Fundamental physics dictates that ultrashort pulses occupy a wide swath of the radio frequency spectrum; at least some of these frequencies, the theory went, were sure to penetrate leaves and branches.
Familiar wireless devices ranging from FM radios to cell phones to wireless computer networks using the increasingly common 802.11b standard all transmit continuous signals on narrow frequencies within the radio spectrum. Digital cell phones on the Sprint PCS network, for example, operate at around 1.9 gigahertz; 802.11b networks (and newer cordless phones) operate at 2.4 gigahertz. These transmissions occupy a thin slice of the spectrum and so generally do not interfere with other systems that depend on radio wave transmissions.
Ultrawideband radios, however, work in a fundamentally different way, emitting extremely short bursts of radio waves-just billionths or trillionths of a second long. Each pulse covers up to several gigahertz of radio spectrum. Information is transmitted by modulating the timing, amplitude, polarity or some other aspect of the pulses. An object’s location can be inferred by methods like those used in traditional radar systems, such as “listening” for the echo of a directional signal and timing how long it takes to return, or triangulating on a target with multiple transceivers. The extremely short pulses used in ultrawideband make the position information highly accurate, down to the centimeter scale-unlike GPS, which is typically accurate only to tens of meters.
Sending information in pulses makes the radios much simpler, and therefore cheaper, to build than typical transmitters. That’s because conventional narrowband radios require, among other design complexities, multiple analog components to tune the frequencies they emit. An ultrawideband transmitter, however, works like a tuning fork. Striking a tuning fork causes it to vibrate, sending out sound waves at a particular frequency. A semiconductor chip in an ultrawideband radio “hits” an antenna with carefully timed electrical pulses; the antenna responds by generating radio waves at every frequency possible. “Ultrawideband systems are just brain-dead simpler to build,” says Carl Howe, an analyst at Forrester Research in Cambridge, MA.
Simpler circuit designs and the pulsed nature of the transmissions also allow ultrawideband radios to transmit at much lower power than other wireless technologies. This gives ultrawideband an edge when it comes to battery-powered devices, since other high-bandwidth technologies require multiple power-consuming components (see “How Ultrawideband Stacks Up”). And the wide swath of frequencies that ultrawideband transmissions occupy helps them travel through walls; even if one frequency is distorted or doesn’t make it through, others still carry the signal.
|Ultrawideband Comes Through|
|An ultrawideband box could transmit different cable channels to TVs throughout a home. Although walls block some of the frequencies used, enough penetrate to reconstruct the signal.|
Another advantage of ultrawideband is its relative immunity to so-called multipath interference. When radio waves encounter obstacles, they bounce off them; echoes that arrive at the receiver out of phase with the original signal can cancel it out. A cordless-phone user walking away from the phone’s base station in his or her home experiences this phenomenon as the fading of the caller’s voice. But with ultrawideband’s extremely short pulses, the original signal reaches the receiver in its entirety before the first echo arrives. Today’s microchips are sophisticated enough to tell the difference between the two-or even to add them together to make the signal stronger. So ultrawideband can operate well in echo-prone places where conventional wireless systems suffer, such as living rooms or crowded cities.
How Ultrawideband Stacks Up
|Technology||Range (meters)||Data rate (megabits/
|Power (milliwatts)||Best suited for||Commercial availability|
|Ultrawideband||10||100||200 (peak)||Short-range, high-speed data transfer (such as wireless video and audio)||2003 (estimated)|
|802.11a||50||30||1,000-2,000||High-speed wireless computer networks||Now|
|802.11b||100||6||500||Computer networking and Internet access||Now|
|Bluetooth||10||1||30||Connecting computing devices over short distances for text transfer||Now|