Wireless "standards keepers" have kept a strong collective eye on the emerging technology known as ultrawideband (UWB) communications, perhaps as much for fear that it could interfere with existing wireless formats as much as for fear that it could become a viable, high-data-rate wireless option. Almost a year and a half after the US Federal Communications Commission (FCC) gave a green light for the use of about 7 GHz of bandwidth for low-power UWB transmitters and receivers, a number of significant players, including Intel, Motorola, and Taiyo Yuden, have announced their intentions to compete in the UWB playground. The future of the technology may depend on how well it can coexist with more established wireless formats, or possibly how quickly it can replace them.

By adopting a First Report and Order last February, the FCC permitted the marketing and operating of certain types of UWB devices, in about 7 GHz of spectrum from 3.1 to 10.6 GHz. That First Report and Order includes standards to protect the operation of existing and proposed radio services from interference caused by UWB devices. In contrast to a conventional communications system in which transmitted energy is focused within a relatively narrow band or channel, an UWB system spreads its transmissions over a fairly wide bandwidth but with a lower effective power level than in a conventional radio channel.

The technology is yet another development of military laboratories to find its way to commercial manufacturers, much like Global Positioning System (GPS) receivers and code-division-multiple-access (CDMA) technology for cellular telephones. The promise of sending high rates of data over low-cost, low-power UWB links has attracted numerous small and large companies and investors, and almost as many proposed "standards." To help sort through the different slants on UWB technology, the Institute of Electrical and Electronics Engineers (IEEE) 802.15.3 Task Group (www.ieee.org/groups/802/15/) is chartered to draft a new standard for wireless personal-area networks (WPANs). The proposed IEEE 802.15.3a specification (expected to be final in late 2004) will include a standard physical-layer definition for short-range, low-power, high-data-rate (100 Mb/s and more) WPANs.

A total of 23 proposals for the new UWB standard were submitted during a March IEEE meeting (from 31 original presentations), representing a variety of different modulation formats. In essence, the proposals fall into two camps on the use of the FCC's allotted bandwidth. One seeks to achieve high data rates at low power levels, without necessarily limiting the amount of FCC-allotted bandwidth that is occupied. The other favors a more "narrowband" use of spectrum, at first concentrating on the spectrum from 3.1 to 4.8 GHz, and then moving upward in frequency when the technology becomes more cost-effective at those higher frequencies.

With last month's meeting of the IEEE 802.15.3a Task Group, one of the proposals stood out as the leading candidate for the final IEEE 802.15.3a standard. The proposal is based on orthogonal frequency-division multiplexing (OFDM) and backed by the Multiband OFDM Alliance (MBOA). The alliance was formed just this June, and includes one of the UWB pioneers, Time Domain Corp. (www.timedomain.com), as well as some leading electronics suppliers, such as Focus Enhancements, Intel, Mitsubishi, Panasonic, Philips, Samsung, and Texas Instruments. Although the proposal garnered only 60 percent of the required 75 percent of the group's vote for confirmation of a standard, the MBOA plans to address task-group members' reservations (including compliance with FCC regulations) in time for the next meeting/vote in September.