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Wi-Fi spectrum battle pits antiterrorism efforts against commercial growth

By Bob Brewin
December 31, 2002 12:00 PM ET

Computerworld - The U.S. Department of Defense has played the antiterrorist and rogue-state card in its attempts to restrict the use of wireless LANs, including those already operating in the lower portion of the 5-GHz band, according to engineers and analysts.
The Pentagon is concerned about the ability of military radar to detect terrorist vehicles as well as stealth aircraft or missiles operated by foreign powers in the face of WLAN interference, the analysts added.
Portions of the 5-GHz band have already been assigned for unlicensed WLAN use in the U.S., Europe and Japan with more than 50 manufacturers making products that operate in these bands.
At a meeting Nov. 11 in Geneva of the International Telecommunications Union (ITU), the United Nations body that oversees spectrum allocations worldwide, the U.S. said it wants the 5-GHz band protected for the use of radars that can "pick out smaller and less reflective targets out of background clutter" and therefore can't afford any interference from WLANs, according to the official U.S. draft position paper submitted to the ITU and obtained by Computerworld.
John Pike, a defense analyst at in Washington, said the references to "small targets and background clutter" pertain to small boats or planes that terrorists could use to attack U.S. forces. He added that the Defense Department is also concerned about the ability of its radars to pick up stealth aircraft. Pike said China is capable of developing stealth technology similar to that used by the U.S. B-2 bomber, which allows the aircraft to hide its presence from most conventional radars.
Will Strauss, a former radar engineer and analyst at Forward Concepts Co. in Tempe, Ariz., said it would be a "small task" for a country such as China to develop its own stealth aircraft.
The U.S. wants to protect these radars by sharply restricting the use of Wi-Fi gear in 5.15-5.35-GHZ portions of the 5-GHz band already opened up for use in the U.S., Japan and Europe.
The U.S. position paper, submitted to the ITU at its November meeting in preparation for the ITU's World Radio Conference (WRC) in June, where the spectrum decisions will be made, endorses a global allocation for WLANs in the 5.15-5.35-GHz band as long as radars are protected by a technique known as Dynamic Frequency Selection (DFS), which shuts down WLAN transmissions when a radar signal is detected.
Bill Calder, a spokesman for Intel Corp., which plans to incorporate WLAN chips into its next-generation mobile computing technology, said that the industry views the Pentagon's DFS restrictions, which he didn't specify, as too conservative. He

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