A team of Virginia Tech researchers is attempting to push ultra-wideband (UWB) technology into the next phase--where military communications can completely elude detection by nearby enemy troops and all manner of home electronics systems can be operated wirelessly.

Funded by a $750,000 grant from the Defense Advanced Research Projects Agency (DARPA), Michael Buehrer and colleagues William Davis, Ahmad Safaai-Jazi and Dennis Sweeney in the Mobile & Portable Radio Research Group (MPRG) at Virginia Tech are figuring out how UWB pulses are propagated and how those pulses can be recognized by potential receivers.

"Utra-wideband technology offers unique advantages for communication, compared to traditional narrow-band systems," said Buehrer, an assistant professor of electrical and computer engineering (ECE) and principal investigator on the project.

A UWB transmission--from a radar device, for example--uses ultra-short pulses that distribute power over a wide range of the radio frequency spectrum, Buehrer explained. Because the power density is dispersed across the spectrum, UWB transmissions ideally won't interfere with the signals on narrow-band frequencies, such as AM or FM radio or cell phone signals.

In fact, UWB transmissions pose so little threat of interference with licensed frequencies that the Federal Communications Commission (FCC) is now allowing companies to operate UWB technology within the 3- to 10-gigahertz range without obtaining radio spectrum licenses.

The bandwidth of UWB signals is so wide that signal energy is available for use at both high and low frequencies. "The low-frequency content of UWB devices can penetrate solid structures," Buehrer said. "Additionally, the high frequency content can detect the details of objects."

These capabilities make UWB radar devices excellent surveillance tools. This also means that UWB has the potential to bring about advances in communications technologies.

Military communications are a good example, Buehrer noted. "Because of the low level of energy in UWB signals, a military unit using the technology could communicate without a nearby enemy even perceiving that transmissions are taking place," he said.

UWB technology also should accelerate innovations for a number of domestic wireless devices, Buehrer said. Currently most home wireless devices, such television remote controls, are quite limited in the amount of data they can send and receive. However, with the wide bandwidth available, UWB signals can achieve significantly higher data rates. Buehrer envisions wireless home computer systems, wireless downloads from digital cameras to computers and wireless connections to thin-screen televisions mounted on walls.

In the first phase of the DARPA-sponsored project, Buehrer and his colleagues will develop models to show the characteristics of UWB transmitted pulses and how those will look to receivers. "We'll discover what receivers see when they encounter UWB signals," Buehrer said.

The research team hopes to continue the project into a second phase, during which they would use the models developed in the first phase to design UWB receivers.

In addition to the DARPA grant, Buehrer and his colleagues have received a Virginia Tech ASPIRES (A Support Program for Innovative Research Strategies) grant for development of a UWB laboratory. The lab would be used by Buehrer's research team and other UWB researchers, including ECE professors Charles Bostian, Dong Ha and Scott Midkiff.

Buehrer believes that the FCC will continue to allow UWB devices to operate without licenses, which should help the technology proliferate. "UWB already has a long history," he noted. "The technology has been used in radar devices for some time. Actually, it's been around since Marconi transmitted the first telegraph signals."