Electronic Design

UWB Development Continues Without Standard Consensus

The IEEE's 802.15.3a working group met again in Singapore the week of September 15 to arrive at a final standard for ultra-wideband (UWB) personal-area networks (PANs). Most members support the orthogonal frequency-division multiplexing (OFDM) method being developed by the Multiband OFDM Alliance (MBOA). Yet the MBOA proposal only garnered 59% of the total vote, while 75% is needed to confirm a standard.

The MBOA standard uses a unique approach to UWB. Instead of the usual monopulses of traditional UWB, the MBOA method uses OFDM over three bands in the 3.1- to 4.8-GHz range (14 bands over the entire 3.1- to 10.6-GHz UWB spectrum). These 528-MHz channels are divided into 128 multiple carriers or tones, each modulated by binary phase-shift keying. The result is a data rate of 110 Mbits/s at up to 10 meters. OFDM makes this transmission more reliable because of its superior performance indoors and in other environments with multipath and fading problems. Even higher data rates of 220 Mbits/s or 480 Mbits/s can be achieved using quadrature phase-shift keying or multilevel quadrature amplitude modulation.

The goal of course is to create the ultimate consumer home entertainment network for TV sets, audio equipment, digital cameras, and camcorders. UWB at 110 Mbits/s can easily stream video to any nearby TV set, set-top box, LCD wall screen, or digital video recorder.

The competing technology uses the more standard pulsed UWB. Here, Gaussian monopulses are modulated with coded data using a biphase technique. XtremeSpectrum Inc. and Motorola are the main supporters of this approach. Xtreme has invested heavily in its Trinity chip set, which is nearing the marketplace. It's no wonder this startup with a major investment in its new chip set is fighting hard to establish its methods as a standard. Still, many believe the OFDM approach will ultimately win.

Meanwhile, development of OFDM chip sets continues in large corporations and in numerous startups. Alereon is developing a two-chip set for the 802.15.3a OFDM standard with a silicon-germanium analog front end and a CMOS baseband with a USB/1394 interface. It's expected to be able to form 4 piconets and hit the 110-Mbit/s rate at 10 meters with quality-of-service and less than 100-mW power consumption.

The UWB working group will meet again in Albuquerque in November. While most expect an OFDM win, most winning standards are determined not only by their technical merit but also by heavy political and business considerations, with tense interaction between the players.

Multiband OFDM Alliance
www.multibandofdm.org

Alereon Inc.
www.alereon.com

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