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Gbit contender enters ultrawideband fray

Posted: 16 Mar 2005 ?? ?Print Version ?Bookmark and Share

Keywords:ultrawideband? uwb? pulse-link? chip? freescale semiconductor?

Throwing down the gauntlet to the established ultrawideband powerhouses, Pulse-Link Inc. has announced chips and details of its own UWB architecture, and formed an alliance to promote it. The moves set the stage for a confrontation with incumbents Freescale Semiconductor Inc. and the multiband-ofdm alliance (mboa).

Pulse-Link calls its approach more secure and spectrum-friendly than those proposed by the other two, while achieving higher data rates and greater range.

"We have 12 patents on this. No one's ever seen anything like this before," president and CEO Bruce Watkins said of the architecture. Pulse-Link's scheme is radically different from the approaches of both the Intel/Texas Instruments-led MBOA and the Freescale-led direct-sequence UWB effort.

Pulse-Link has demonstrated its architecture, but "kept the details under wraps until now because we didn't want to get stuck in a debate on the theory," Watkins said. "We wanted to wait until it was proven out." Those demonstrations at 667Mbps don't approach the capabilities of the architecture's physical layer, which can support 2Gbps operation, he said. A first-generation front-end transceiver chip reaches 1Gbps over distances of 2m to 3m and 1Mbps at wireless-LAN ranges of 100m"enough for streaming media throughout the home, and that's something the others are not even talking about right now," he said.

Pulse-Link's C-Wave architecture embeds data in a 1GHz-wide continuous wave, Watkins said. The direct-sequence (DS) UWB approach favored by Freescale uses a pulse; the MBOA's multiband orthogonal frequency-division multiplex scheme, multiple carriers. Pulse-Link's wave covers the 3.3GHz to 4.7GHz region and is modulated using binary or quadrature phase-shift keying. "This means we don't need mixers, oscillators, or up- or downconverters," Watkins said.

Simplicity was a fundamental objective. "We wanted to take everything out of the RF domain and put it in digital as soon as possible," said John Santhoff, Pulse-Link's founder and CTO. "So the baseband is the real breakthrough; the front end is relatively simple." That said, Watkins emphasized the advanced ADC at the heart of the design. "This is very low power with a high dynamic range of 40dB," he said.

In the digital domain, Pulse-Link implemented a number of dynamic link adaptation and flexible forward error-correction techniques that, when combined, provide extended range, spectral flexibility and lower power. Techniques include variable spreading codes that Watkins said can improve signal gain by up to 25 dB, resulting in higher data rates at shorter range.

Pulse-Link has first silicon for its transceiver from its foundry, Jazz Semiconductor. Watkins said it's made in an 0.18-micron silicon germanium process. Fujitsu will implement the company's combined media-access control/physical-layer (MAC/PHY) chip in a 0.11?m CMOS process. It will be available in April, said Watkins, who added that the full chip set will be sampling in August. The company plans to combine the transceiver and MAC/PHY chips next year.

To promote the technology, Watkins said, the company has worked with independent services provider AMS to form the C-Wave Alliance, which will compete with the MBOA and the DS-UWB-centric UWB Forum. Though Pulse-Link is now the only member, Watkins expects to announce content providers as members soon. The alliance does not yet operate a website.

Pulse-Link has also announced an evaluation kit that will be available to alliance members. "We want to make sure that the companies that get this are committed to what we're doing," said Watkins. It comprises four pc boards, one each for the MAC, PHY, transmit and receive portions. "When we're finished characterizing the transceiver, we'll be combining the transmit and receive boards into one," he said.

The evaluation kit will also be used for demonstrations before the Federal Communications Commission's Office of Engineering and Technology in the first week of March. So far, Freescale has the only FCC-certified chip for high-rate UWB communications.

- Patrick Mannion

EE Times

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