Ultrawideband radio attacks spectrum drought
By Ian Cameron
Electronics Times 
09/26/00, 4:56 p.m. EST

LONDON — Ultrawideband communications, which uses timed high-frequency
pulses to transmit over radio rather than conventional continuous
modulated signals, may be one of the communications industry's best-kept
secrets. But it won't stay that way for long, according to the company
developing the pulse-timing technology, which it describes as the answer
to just about every communications issue around. 

"It's like the Internet in the early 1990s — this is the dynamic," said
Ralph Petroff, president and chief executive officer of Time Domain
Corp. (Huntsville, Ala.). "[But] right now people are scratching their
heads. If anything, the potential for ultrawideband has been
underhyped." 

For starters, Petroff said the technology could solve "spectrum
drought," which he called "the only thing that can slow down the
wireless industry and bring it to its knees — we are running out of
spectrum." 

Petroff believes it's possible to get 10 to 30 times the number of
equivalent communications channels into the same spectrum when using
ultrawideband's pulsed techniques rather than conventional signaling. He
anticipates the advent of ultrawideband systems in three years or less. 

In May the U.S. Federal Communications Commission issued a Notice of
Proposed Rulemaking for the technology — in essence, a proposal to
consider permitting use of the technology on an unlicensed basis. This
is seen as a stepping stone toward a final rule for its deployment "in a
manner compatible with existing radio services," though the FCC has
advised that further research and testing are needed in bands below 2
GHz. Test results are expected by late next month.

Petroff described ultrawideband as "a radio world in which everything is
backwards. It's radio without continuous sine waves, without assigned
frequencies, without resonance or power amplifiers" — a place where the
multipath interference problems that dog many radio technologies are
"not an enemy, but a friend." 

Applications range from enhancing videogames so that people can play
against each other across whole neighborhoods to more serious uses. The
technology has been on trial with U.S. emergency services. Time Domain
received a waiver last year from the FCC to produce 2,500 RadarVision
devices —  "through-wall" motion detectors that can report the location
of people. One possible use of a solids-penetrating radar system is to
find survivors after earthquakes and other disasters, "using a fraction
of the transmission power [of conventional systems]," said Petroff.
"It's a better mousetrap." 

Ultrawideband can be used for covert communications among law enforcers.
It can also distribute wireless services such as phone, cable and
computer networking throughout a building. The U.S. Army Space and
Missile Defense Battle Laboratory has tested its use as a local-area
network technology. 

"Never before has there been a wireless technology that fuses
communications, precise positioning and radar," said Petroff. 

Noisy effects

Yet for all its promise, ultrawideband has drawn its share of fire,
mostly on account of the pervasive effect of the technology on existing
communications. The global positioning by satellite (GPS) community and
other groups worry that ultrawideband radios could cause interference
with their signals. 

The GPS consortium, the Federal Aviation Authority, and some cellular
telephony and TV operators have complained that large numbers of such
systems would cause interference by raising the overall noise floor
right across the spectrum. 

"I think it's a political issue, not a technological one. There is no
difference in this and other low-power radio emitters," Petroff said,
citing laptops and palmtops. "The GPS community would like all these
devices to have zero tolerance. That's not possible." 

The pulses in ultrawideband comms are based on forms known as Gaussian
monocycles. The shape of the monocycle effectively spreads the energy in
each pulse across a bandwidth of about 3 GHz. The energy cuts across
most of the TV bands, cellular telephony and satellite channels, plus a
few military channels. This is the main reason ultrawideband has run
into problems with other users. 

Time Domain claims that the signals are undetectable, even at short
range, by a receiver not designed to receive ultrawideband signals,
because the pulses are sent at sub-milliwatt power levels and the energy
is spread across a huge range. 

Petroff now thinks the FCC has been largely persuaded by ultrawideband's
merits: "The regulatory hurdles are a lot smaller than they used to be,"
he said. 

Time Domain has raised $70 million so far, and has spent between $30
million and $40 million on R&D and intellectual property. Investors
include Sony and telecommunications operator US West. Time Domain has
quadrupled its head count to 200 in the past year, and is looking to
establish offices in London, Tokyo, Munich and Seattle. 

Petroff said the United Kingdom is playing an important role in bringing
the technology to market in Europe. Racal Research is investigating how
ultrawideband could be used to supplement the signal from Galileo, the
proposed European equivalent of GPS, inside buildings. 

Petroff believes products that incorporate Time Domain's chip sets,
which now exist as prototypes, will roll out in one to three years. 


— Additional reporting by Chris Edwards. 

Ian Cameron is business editor of Electronics Times, EE Times' sister
publication in the United Kingdom. 

http://www.eetimes.com/story/OEG20000926S0057