UWB Caught on the Hop

The MultiBand OFDM Alliance (MBOA) led by Texas Instruments Inc. (NYSE: TXN) has won one of the first major battles to get its preferred technology adopted by the Institute of Electrical and Electronics Engineers (IEEE) Task Group that will draft a short-range, high-speed, ultrawideband (UWB) wireless networking standard.

However, Motorola Inc. (NYSE: MOT) and startup XtremeSpectrum are still pushing their own rival technology and claiming that the TI-backed approach breaks the strict Federal Communications Commission (FCC) rules about this sexy [ed. note: Well, it certainly has geeks the world over shyly fingering their pocket protectors] new radio technology (see Report Hypes Ultrawideband).

The IEEE Group is planning to draft a UWB specification capable of delivering 110 Mbit/s over a distance of 10 meters -- that's 100 times faster than the data rates the comparable Bluetooth standard can achieve today. However, before the propellerheads can get out their slide rules and lined paper they have to vote on which technology to adopt. Originally there were 23 (!) proposals on the table, this has now been whittled down to three (see UWBers Get Busy in Texas).

Last week, the MBOA proposal (see UWB Heavyweights Get Together) received over 90 supporting votes, with 66 votes against it, when it was put before Task Group members, according to Bob Heile, chair of the IEEE 802.15 Working Group on Wireless Personal Area Networks. However, it failed to achieve the 75 percent majority required to permanently exclude two other competing proposals from the process.

According to various sources, many of “no” voters were concerned that the MBOA technology would take longer to develop than alternate proposals.

The naysayers are also concerned that the frequency-hopping modulation techniques used by the MBOA contravene FCC regulations, which require frequency-hopping to be turned off while tests are being run to check that UWB devices comply with strict power emission limits.

Frequency-hopping refers to the repeated switching of frequencies during a radio transmission, where the transmitter "hops" across available frequencies according to a random or preprogrammed algorithm.

John Reed, a senior engineer invloved with drafting the FCC's UWB regulations, says the frequency-hopping issue is crystal clear. “When testing, the rules require that you stop the frequency hop from hopping, period,” he told Unstrung earlier today.

As is often the case, however, the rules are open to interpretation. Matt Welborn of XtremeSpectrum, for example, has presented a paper to the IEEE which argues that OFDM multiband technology falls afoul of the rules (download this document here: PDF 293KB), while members of the MBOA had earlier presented a paper to explain why multiband systems are allowed under the FCC rules (download this document here: Word 157KB).

Confusingly, both papers cite the same paragraph from the relevant FCC Report & Order document. Yesterday, Xtreme and Motorola filed a request for a declaratory ruling by the FCC, in which they urge it to adopt a position that would blow the MBOA proposal out of the game.

The next meeting of the IEEE UWB group is in Singapore in September. If the MBOA proposal passes the 75 percent threshold this time, the process moves on to the next stage, says the IEEE’s Heile. “If it does not, the process resets and we work through it again.”

— Gabriel Brown, Research Analyst, Unstrung