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Ultrawideband companies gear up for FCC ruling

Posted: 05 Feb 2002 ?? ?Print Version ?Bookmark and Share

Keywords:uwb? ultrawideband? wireless home networking? multimedia? federal communications commission?

On the brink of this month's expected Federal Communications Commission ruling on ultrawideband (UWB) technology, a growing number of startups and established players are aiming their development efforts at leveraging UWB for streaming-multimedia applications in wireless home networking.

Proponents claim UWB technology could be ideal for next-generation physical-layer (PHY) chips for high-rate, short- to medium-range wireless home networking. That optimism is based on UWB's potentially low-cost implementation; low power consumption; high throughput, enabled by the wide bandwidth used; and accurate positioning information.

But UWB's promise won't be realized until regulatory hurdles are cleared. The FCC is expected to take action on Feb. 14 that either could create new rules or amend existing guidelines for UWB deployment. The commission has been working with government agencies and industry backers and opponents of UWB to craft rules that would allay concerns about interference with existing navigation systems and wireless networks.

Device makers are remaining optimistic. "UWB's very high data rate potential, at 500Mbps, can present a pretty interesting possibility for a wireless version of USB 2.0," said Ben Manny, director of wireless technology development at Intel Architecture Labs. One caveat: "At what cost, we don't know yet," Manny said.

Opponents claim that UWB emissions, designed to spread across a range of already assigned FCC frequencies, could interfere with such existing services as the Global Positioning System (GPS) and PCS wireless.

The technology of UWB spreads a very low-power signal across a wide swath of spectrumfrom 3GHz to 6GHz, depending on FCC parametersdiluting its energy to well below the detection threshold of conventional receivers. Conventional narrowband and wideband systems use RF carriers to move the signal in the frequency domain from baseband to the actual carrier frequency where the system is allowed to operate. In contrast, UWB, often described as a "carrier-free" system, can directly modulate an "impulse" that has a very sharp rise and fall time, resulting in a waveform that occupies several gigahertz of bandwidth.

The U.S. Department of Defense has been leading the charge to establish emission limits for UWB technology and has found an ally in the Commerce Department's National Telecommunications and Information Administration (NTIA), which helps oversee U.S. spectrum policy. The Transportation Department and NASA, concerned about aviation safety, continue to demand a higher frequency threshold for intentional emissions from UWB devices as a way to prevent interference with radars operating near 6GHz. They are pressing the FCC to authorize only UWB devices operating above 6GHz.

Meanwhile, in a Jan. 11 letter to NTIA, a senior Pentagon official called for limits on UWB emissions below 4.2GHz. He also argued that out-of-band emissions should meet strict DOD standards designed to prevent interference with GPS.

"We believe that compliance with these parameters can easily be achieved by installation at the input to UWB transmitting antennas of a high pass filter with a cutoff at 4.2GHz to produce an emission mask," the official wrote. That would allow "full implementation of UWB technology" above 4.2GHz.

As the regulatory debate over UWB reaches end game, UWB companies like XtremeSpectrum Inc. (Vienna, Va.) say they have forged compromises with the DOD on most interference issues, including the use of emission masks below 4.2GHz. The DOD proposal on UWB emission limits would exempt imaging systems such as ground-penetrating radars.

UWB proponents say the FCC has a tested solution at its disposal that would allow UWB to go forward while protecting existing spectrum users. "At this point, all the science has been worked out; the issues that remain are mostly political," said Martin Rofheart, chief executive of XtremeSpectrum.

Analyst Navin Sabharwal at Allied Business Intelligence Inc. (Oyster Bay, N.Y.) asserted that "most companies believe the approval of UWB is not a case of 'if' but 'when.' However, given the resistance of the military and the GPS community to UWB, it is possible that UWB's approval may be delayed further." Chances for the FCC's UWB approval on Feb. 14 are "probably 50-50," he added.

Ready-made silicon

Many UWB technology companies, including patent holders XtremeSpectrum and Time Domain (Huntsville, Ala.), claim they are ready to sample commercial UWB chipsets once the FCC makes a favorable ruling.

Chris Fisher, vice president of XtremeSpectrum, said the company's technology can deliver a 100Mbps or faster data rate at 200 mW for a bill of materials that comes in under $20.

"We can deliver our working silicon into the hands of consumer electronics companies in mid-2002," Fisher said. The first UWB-enabled consumer products could be available by Christmas 2003, he said.

Time Domain is developing a second-generation UWB chipset scheduled to ship commercially later this year. Jim Meyer, vice president of business development, said the company's next-generation PHY could deliver "hundreds of megabits per second of throughput" at a 1m distance when used for a high-rate wireless personal-area network (PAN) standard like IEEE 802.15.3.

Others said the ability to render UWB circuitry in CMOS technology will drive the technology into the consumer market. "As CMOS scales from 0.25 to 0.18 to 0.135m, so does the UWB circuitry," said Bruce Watkins, president and chief operating officer of Pulse~Link Inc. "As a result, some call UWB 'Moore's Law Radio.' "

500Mb throughput goal

The UWB direct-conversion receiver avoids multiple RF and IF stages, local oscillators and mixers required by traditional, superheterodyne radio architecture. The simple UWB spin is said to translate to lower material and assembly costs.

Intel, meanwhile, has developed a UWB prototype based on discrete components to show that "100Mbps data throughput is fairly easy to do," Manny said. Intel's research team is seeking to push throughput to 500Mbps by the end of 2002.

Intel has not decided whether to enter the UWB chip business. It already has various wireless products based on such standards as Bluetooth, HomeRF and 802.11x. "When the new UWB technology comes into the market, we need to understand how to minimize interference with existing wireless products," Manny said.

Pulse~Link, which last year bought rights to intellectual property developed by Fantasma Networks, is in final design review on two of the three chips in its initial solution, Watkins said. It has delayed its final chipset design pending FCC approval. "You hate the thought of going through the expense of finally achieving successful tapeout and then having to re-engineer and respin because the FCC won't allow you to deploy what you have," Watkins said.

Many UWB vendors are focusing on multimedia streaming applications, said Allied Business Intelligence's Sabharwal. "Home networking and especially multimedia streaming are the most lucrative applications of UWB technology," he said.

That's because wireless networking schemes for portable entertainment devices that gobble bandwidth and must be affordable constitute "a portion of the market that has not been addressed up to now," said XtremeSpectrum's Fisher.

UWB proponents do not claim the technology will replace existing wireless networking standards. Instead, they said, UWB offers advantages unavailable in the existing technologies.

"The higher throughput alone perhaps wouldn't justify UWB," Time Domain's Meyer said. Other key UWB features, he said, include its inherent location awareness, coexistence with narrowband standards and very low power consumption.

Junko Yoshida and George Leopold

EE Times

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