New doubts have been raised over the future of ultra-wide band (UWB), by the chair of the group creating a standard for the fast networking technology.

If Europe and Asia apply more restrictions to the technology than the FCC in the US, the technology may not perform well enough to displace Wi-Fi, which is constantly improving, said Bob Heile, chair of the IEEE 802.15.3a working group.

"I believe we will see regulations in Europe that are substantially more restrictive than those applied by the FCC," said Heile, in France for a conference on the ZigBee sensor protocol. "Japan is likely to be even more conservative. If that happens, how good is the performance going to be?"

Stiff regulations would limit UWB to a smaller slice of spectrum, and reduce its speed and range. It would then have more trouble competing against faster versions of Wi-Fi. In two years' time, 802.11n will be established, with a theoretical limit of 110 to 200Mbit/s. "By the time you put in overhead factors, that's 45Mbit/s or throughput," he explained. Although UWB should have 480Mbit/s at short ranges, it would drop off with distance - particularly if the regulations limit the spectrum it can use. "By the time you've gone across a room, the data rate could be more like 802.11n."

Heile was not convinced by Ofcom's optimism that operators can learn to love UWB: "The operators literally don't want anyone else in their spectrum."

He also disagreed with Techworld's suggestion that the alliance with Bluetooth may help UWB get regulatory approval. "Will Bluetooth reconcile phone companies to UWB? I don't think so," he said. "It's a good marketing move from Bluetooth, though."

In his view, regulations were likely to be a more serious problem than the deadlocked UWB standards dispute in the IEEE, although he sounded weary of this argument: "I feel more like a referee than a chair," he said.

UWB vendors did not agree with Heile. "If they cut out the lower frequencies, I can move higher," said Bruce Watkins, chief executive of Pulse-Link, a vendor which promises to take speeds well beyond the 480Mbit/s currently proposed, and which recently joined the UWB Forum. "I can get the same throughput at 8GHz as I can at 4GHz."

He admitted, however that at higher frequencies, there is more absorbtion, so the effective range (and the throughput at a given range) goes down: "We can get the same throughput, but it will limit the functionality." Only UWB can promise enough speed to stream high definition TV, said Watkins.

"There's nothing about 802.11n that bothers my business model," said Watkins. "And I don't think there's anything about it that really invalidates [rival UWB group] Wimedia's business model."

Watkins is hopeful that next week's meeting of the UWB group of the international telecoms standards body, the ITU, may help.

"Things are not where we want them to be," he said, "but submissions [from the operators] have relaxed from six to nine months ago. They are still not appropriate, but the trend is better, not worse."