 | December 1, 2000 |
Feel the pulse
OUTLOOK: Ultra-wideband wireless nears market debut
Bluetooth, 802.11b, 3G, and other continuous-wave wireless communication schemes hold great promise in convergence applications, but some upstart innovators believe pulse-based wireless technology may provide a better alternative. Indeed, investors, developers, and the FCC are eyeing a revolutionary technology that allows a transmitter to reuse radio frequencies already allocated to millions of devices, including cell phones, satellites, TV stations, and emergency-services radios.
Ultra-wideband (UWB) technology uses narrow pulses to spread a signal over as much as 5 GHz of the available spectrum, thereby creating only infinitesimal interference within any specific frequency band. UWB signals emanate from a transmitter as a series of precisely timed pulses, each as short as a few picoseconds. Like CDMA systems, UWB can stuff multiple channels into the same physical area and frequency band. UWB also has potential beyond communications, in applications such as motion- and location-detection.
UWB proponents see the technology as a perfect replacement for the continuous-wave schemes in wide use today. For instance, Time Domain, arguably the inventor of UWB, developed a prototype 50-microwatt system capable of 5 Mbit/sec data rates and a range of 10 meters. For comparison, the scheme provides a data rate more than five times faster than Bluetooth, uses less transmit power, and potentially supports more channels.
So what's holding up the move? Technically, a UWB system needs mucho MIPs to perform its magic, and only recently have semiconductor advancements made UWB feasible in low-cost systems. In fact, detractors claim that even though UWB uses low transmit power, power requirements for the processor in the receiver might prove problematic in battery-powered portable devices. A now-settled legal skirmish between Time Domain and Lawrence Livermore also stymied development.
A bigger concern has been that UWB transmissions are illegal. But that appears to be changing. Time Domain received an FCC waiver last year to sell a limited number of UWB-based motion-detection products. And the FCC may be poised to allow broader deployment. In April, the FCC approved a proposal to consider unlicensed UWB transmissions. While the FCC mulls the proposal, the National Telecommunications and Information Administration is performing detailed interference testing. Completion had been expected by the end of October, but is now slated for February 2001. UWB proponents expect approval soon thereafter.
—Warren Webb
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