News

Companies Pare Down UWB Proposals

The task group charged with defining a new ultrawideband standard was back in Dallas last week for another round of proposals as the ultrawideband industry struggles to agree on a multimedia standard.

by Vikki Lipset Managing Editor of Ultrawidebandplanet.com [May 20, 2003]

The latest meeting of the Institute of Electrical and Electronics Engineers (IEEE) 802.15 Working Group for Wireless Personal Area Networks (WPAN) was a precursor to the "down select" process that will begin in July, when the 802.15.3a Task Group will vote on the remaining proposals.

The group's goal is to develop a high-speed alternative physical layer standard for applications that involve imaging and multimedia. Before they can decide on a standard, though, they'll need to whittle down the 23 proposals that were presented at the IEEE meeting in March.

As previously reported, the majority of those proposals advocated a multiband approach to the technology, which would divide the 7.5 GHz of spectrum allotted for UWB by the FCC into smaller bands of 500 MHz to 700 MHz that can be added and dropped based on interference from other systems.

The UWB Multi-Band Coalition, which is comprised of 14 companies, including Intel, Philips, Mitsubishi and General Atomics, is currently working to merge the various multiband proposals into one. The group held its own meeting in Dallas this week to discuss the merge process and to recruit new members. "There are a lot of secret handshakes going on behind the curtain trying to facilitate significant merging between now and the July meeting," said Jason Ellis of General Atomics.

It appears that they've already made some progress, as the number of proposals in this round was down to 13. Israeli chipset maker Wisair presented an updated proposal that included recommendations from the Coalition. UWB startup Time Domain is expected to present the final merged proposal at the July meeting in San Francisco.

Not all of the multiband proposals came from the Multi-Band Coalition, however. Texas Instruments (TI) is proposing its own flavor of multiband that uses orthogonal frequency division multiplexing (OFDM) to transmit information. TI's proposed solution divides the UWB spectrum into 14 bands of 528 MHz each. These bands are then divided into smaller bands of 4 MHz, called tones.

Anuj Batra, who works in TI's DSP R&D center in Dallas, said that the approach provides global scalability since the tones can be dynamically turned on or off in order to comply with different regulations.

The OFDM approach is a "digital heavy solution" that offers shorter design times and lower costs compared with analog, said Steve Turner, TI's UWB business development manager. Since more of the processing is done in digital than analog, it's easier to scale down designs, he said.

Motorola and Xtreme Spectrum, on the other hand, don't think multiband is best suited for the consumer electronics applications, such as high definition video transfer, that are expected to be the early "killer apps" for UWB. With a data rate capability of 110 Mbps and a range of 10 meters, UWB can stream multiple high-definition video streams wirelessly from a set-top box to TVs throughout the home. High-definition quality content runs at about 35 Mbps.

Motorola and Xtreme jointly presented a proposal at this week's meeting that advocates a dual-band, direct sequence code division multiple access (CDMA) approach for the standard. In March, Motorola's Semiconductor Product Sector announced that it would use Xtreme's UWB technology in its own chips.

Chris Fisher, Xtreme's vice president of marketing, said that for consumer electronics applications, it is crucial that the quality of the wireless link must be as good as the wired one. "There is a fundamental physics benefit that comes from wideband radio transmission vs. narrowband. We can provide wirelike transmissions with wideband. If we narrow up the bandwidth, we lose that."

In addition, he said, the standard must allow a home network to support many users while being able to provide high data rates to each of them. With multiband, there is a tradeoff of data rate vs. number of users, he said.

"The problem with the multiband 'frequency hopping' approach is you can't hop to the next frequency until the wave you launched in the initial frequency has settled down. It limits the rate at which you can move to next channel and limits the amount of data you can push through at any time."

Fisher said it's difficult to assess at this point which flavor of UWB will ultimately emerge from the standards process. There's still a long way to go; a proposal needs the approval of 75 percent of the Task Group before it is officially selected as the standard.

General Atomics' Jason Ellis said he doubts the standard will be finalized by the end of the year, but he thinks there will be at least a clear direction of which way it's headed. "You may not have a final text, but you'll be on your path."

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