Computerworld January 6, 2003
U.S. Tries to Restrict 5-GHz Wireless LANs; Worried about interference with military radar
By Bob Brewin
The U.S. Department of Defense is seeking to restrict the use of wireless LANs in the lower portion of the 5-GHz frequency band because of concerns about possible interference with military radar.
Portions of the 5-GHz band have already been assigned for unlicensed WLANuse in the U.S., Europe and Japan. But in a draft position paper submitted to the International Telecommunication Union (ITU), the U.S. government said it wants the 5-GHz band protected for radar systems that can pick "smaller and less reflective targets out of background clutter." That phrase refers to small boats or planes that terrorists could use to attack U.S. forces, said John Pike, a defense analyst at GlobalSecurity.org in Washington. He added that the Defense Department is also concerned about its ability to detect stealth aircraft that can hide from most conventional radar systems.
High Stakes
Badri Younes, director of spectrum management at the Pentagon, acknowledged that the war on terrorism has raised the stakes for radar operations. Attackers "could be coming from anywhere," Younes said, adding that the military has to be able to ensure that its radar systems can work without interference from WLANs.
The government's position paper was prepared for a meeting of the ITU in Geneva on Nov. 11. The ITU, the United Nations body that oversees spectrum allocations worldwide, plans to decide on the 5-GHz matter and other issues at its quadrennial World Radio Conference (WRC) in Geneva in June.
In the draft proposal, a copy of which was obtained by Computerworld, the U.S. said it wants to restrict the use of Wi-Fi WLANtechnology between 5.150 and 5.350 GHz. The government called for radar systems operating in that band to be protected by a technique known as dynamic frequency selection (DFS), which would shut down WLAN transmissions if a radar signal was detected.
Bill Calder, a spokesman for Intel Corp., declined to specify the DFSrestrictions being sought by the Pentagon. But he said that IT vendors view them as too conservative and are trying to reach a compromise with the government before the WRC meeting.
"We do not want to see that low band unduly restricted," Calder said.
Younes said Pentagon officials are willing to work with companies to devise a proposal that supports national security interests and the needs of WLAN vendors and users.
But Rich Redelfs, president and CEO of Atheros Communications Inc., a Sunnyvale, Calif.-based maker of chip sets for 5-GHz WLANs, described the attempt to limit use of the technology as "trying to put the genie back in the bottle."
Clyde Ensslin, a spokesman for the National Telecommunications and Information Administration, a division of the U.S. Department of Commerce, said the draft proposal represents the views of all federal agencies, including the Federal Communications Commission.
The radar section pertains to both military and commercial radars, including advanced systems that commercial pilots could use to detect small planes, Ensslin said.
Copyright © 2003 Computerworld, Inc
