Fixed Wireless Business

Ultra-Wideband: Great
Promise, But No Guarantees

Theoretically, UWB systems represent the next logical step for wireless communications. The use of low-power radios to send out short-duration pulses over various frequencies without creating interference for other RF systems operating in the same bands is quite appealing. Now prove it will work.

by Gerry Blackwell [June 11, 2002]

Ultra-Wideband (UWB) radio was recently cleared by the Federal Communications Commission for use in 3.1 to 10.6 GHz spectrum. UWB may be unique among "new" technologies in that it has the hype built right into the name. Even if you don't know what ultra-wideband is—and most people don't—it sure sounds good.

Advocates have escalated the hype even further. According to some, UWB is a panacea, the wireless "non plus ultra." The main applications of UWB are radar and global positioning systems (GPS), as well as communication networks.

UWB systems use very low-powered radios to send out very short-duration pulses over a very wide range of frequencies—without interfering with other RF systems in those bands. Theoretically. UWB systems could initially deliver bandwidth in the 40 Mbps to 60 Mbps range, and ultimately 100 Mbps and above.

,"UWB sounds good, maybe too good to be true, and that has been a problem, says Rob Mulloy, vice president and chief operating officer at Germantown, Maryland-based UWB system developer Multispectral Solutions Inc.

"Some of its proponents have hyped ultra-wideband as the next greatest thing to the transistor or sliced bread" says Mulloy. "It has hurt the technology."

The power of low-power
UWB does, to be sure, hold out interesting promise—including for wireless Internet service providers (WISPs). Among other things, UWB systems could eventually be used to build cheap, fast, wireless last mile access systems, capable of resolving problems inherent to current spread spectrum technologies.

That's why WISP operators like Bryan Brooks of Sky Networks, an Urbana-Champaign, Ill., service provider, and Bill James of Kern County, California-based High Desert Wireless joined the Ultra-Wideband Working Group, an industry body formed three years ago ostensibly to promote the technology.

"We wanted to be sure we were in on the next big thing," says James.

But the next big thing may take a while to hit the market.

The UWBWG, which was supposed to function like Winforum, has been less than proactive, says Sky Network's Brooks. , the working group has been less than proactive. He was amused to learn that his name was on a list of members at a Web site, since he had not heard anything from the organization since signing up.

He was amused to learn that his name was on a list of members at a Web site, since he had not heard anything from the organization since signing up. Multispectral declined to join the group because it was turning into a marketing vehicle for UWB rival Time Domain Corp. of Huntsville, Ala., Mulloy says.

More to the point, the FCC Report & Order issued in February gave users leave to deploy UWB systems with power levels that would make them suitable for radar and GPS, but only local and personal area networks (LANs and PANs) on the communications side.

Don't obstruct the airwaves
Despite the theoretical capabilities of the technology, concerns about higher-power, higher-data-throughput UWB systems interfering with other RF systems remain. "There are still unanswered questions," Mulloy admits.

The only thing that testing has concluded to date, he says, is that lower-powered systems are less interfering. This is not to say that higher-powered, longer-range UWB systems could not coexist with other RF systems in a given spectrum band if properly designed, it just needs to be proved.

Multispectral and others will be building commercial systems over the next several months that should demonstrate more conclusively the behavior of UWB in different application situations, in various spectrum bands and at different power levels.

Mulloy's firm hopes to have beta systems ready for testing within six months. They will be based on the successful field communications/GPS and radar systems the company has built for military customers.

The FCC has said it will revisit UWB in six to twelve months. Proponents are hoping the federal regulator will open up the rules at that time to allow different kinds of systems—including last mile access systems. However, it is by no means a foregone conclusion that this will happen, Mulloy says. And rules in some areas could even tighten.

While Multispectral is initially focusing primarily on applications with immediate commercial viability—radar, GPS and household video distribution systems—it is also expending some effort towards a "proof of concept" in the area of last mile access systems.

"We believe there are areas within the 7 GHz of spectrum [3.1 to 10.6 GHz allocated by the FCC] where there should be enough bandwidth to use UWB for this application on a not-to-interfere," he says.

There is also a possibility that other jurisdiction, perhaps Canada, may give UWB users a freer hand.

His company would seek clearance to deploy proof-of-concept UWB-based last mile access systems first in rural areas—where there is a greater need—rather than trying them in congested RF activity areas such as national airports, Mulloy says.

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