xMax sparks low power wireless revolution

November 05, 2005

A little-known start-up has demonstrated wireless broadband 1000 times more efficient than WiMax – and claims the technique could also make wireless LANs that will run for years on watch batteries.

xG Technology, based in Sarasota, Florida, used a transmitter not unlike a cordless phone base station, operating in the unlicensed - and crowded - 900MHz band, to send a 3.7Mbit/s data signal to a radius of 18 miles across the suburbs of Miami, using 50mW and an omnidirectional antenna.

The data rate and specifications don't exactly match xG's original plan, which we reported in July, as the demo uses a narrower band and a lower data rate. However, with an omnidirectional antenna, the demonstration appears to have transmitted a signal at a power density other schemes would find impossible. The company's xMax technology uses a novel modulation scheme, described at xG's own site.

"xMax is unconventional," said Stuart Schwartz, professor of electrical engineering at Princeton Universithy, who has scrutinised xG's demonstration set-up, speaking at the xMax demonstration. "It is clever and innovative, but it is not magic. It uses single cycle modulation, and needs much less power than other technologies."

xG has promised to have commercial systems ready by the second half of next year, which can be sold off-the-shelf. "We're in discussion with channel partners, to make a shrinkwrapped package that would allow anyone to set up as a wireless ISP," said Mooers."In the longer term we see it rolling out to chips that will be in millions of different units."

The same technology could also make licensed broadband services more efficient, said Professor Schwartz: "WiMax would require 90 base stations to cover the same area."

Before any of this happens, more demonstrations are needed, to show the system is robust against interference and multipath, and can operate in an area more crowded than 18 miles of swamp. It will also need to be approved by the FCC and other regulators round the world.