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Transmit signals need to be tamed in WiFi - Eaton calls for standards work

Dennis Eaton, chairman of the WiFi Alliance, predicted today that the market would probably "evolve" a standard for transmit power control, which would prevent the problem of too many radios "swamping" each other in a crowded area.

Eaton was speaking after his keynote speech at London's Enterprise Wireless Technology show at Olympia today, where he (predictably enough) emphasised the importance of conformance testing - which is what the Alliance does.

Transmit power control (TPC) is a feature of 802.11h - the European-inspired improvement on 802.11a WiFi - and it specifies that no wireless device should transmit with more power than it needs to reach the nearest access point.

One advantage is that it saves battery power; but another is that distant users aren't drowned out by close ones.

"We're already seeing some companies advocating this technology for 802.11b and 11g wireless," said Eaton, "and typically, when they start advocating it, they are probably developing the technology. So I'd expect to see proprietary schemes for controlling the transmit power appear over the next year or so."

What Eaton hopes, of course, is that the IEEE will take a hand, and step in with a standard - probably, one based on 11h.

"We're seeing dual-standard devices increasingly," he said. "That means that the ability to do it is going to be there, and it's just a question of developing a standard way to manage TPC for 11g as well as 11a or 11h frequency bands."

The lack of TPC has been blamed by some, for the failure of some large-scale WiFi setups - at events like the German exhibition, CeBIT, or the Microsoft TechEd conf in Barcelona.