Jams ahead for wireless lans

Too much of a good thing to crowd airwaves

Just as wireless LANs are starting to hit the mainstream, users are facing warnings about overloaded bandwidth.

The spectrum used by the LANs' signals is expected to become crowded so quickly that companies could find themselves replacing all of their wireless equipment in just two to three years, as wireless technology is forced to move to less-obstructed, higher frequencies.

"At some point, this band will get filled up. It will be perceived as a garbage band, and then we'll move to 5 GHz," said Phil Belanger, vice president of wireless business development at Wayport Inc. in Austin, Texas, which plans to install wireless LAN networks in 20 airports this year.

Wireless LAN users - who enjoy speeds of 11M bit/sec. and network connectivity without cables - share the 2.4-GHz frequency band not only with other wireless LAN users but also with other devices. These range from microwave ovens to cordless phones to short-range Bluetooth devices, designed to provide wireless connections between laptops and printers.

In addition, major network equipment vendors have developed wireless LAN products for home offices, providing mobility for laptops equipped with $99 wireless LAN cards.

These and other developments are expected to drive 41% growth in the wireless LAN market over the next two years, peaking at 33.9 million units in 2002, according to Cahners In-Stat Group in Newton, Mass.

David Ziembicki, chief technology officer at Global Digital Media.com in Boston, which is installing wireless LANs in airports in Boston and Philadelphia, said his company has "concerns about interference" in the 2.4-GHz band.

He suggested that corporate information technology managers considering deployment of a wireless LAN "conduct a site survey like we do to determine existing sources of noise and frequency interference" and then work to alleviate as many of those as possible.

Brent Miller, a senior engineer at IBM's pervasive computing division in Research Triangle Park, N.C., said anyone planning to use 2.4-GHz wireless products "needs to account for interference," including static between Bluetooth and wireless LANs. But "under the worst of circumstances," he said, "performance degrades gracefully."

Jan Haagh, wireless product manager at Lucent Technologies Inc.'s Orinoco division in Utrecht, Netherlands, said wireless LAN manufacturers need to design systems "that can cope with microwave ovens. . . . They power on and off, and we have a way to make our packets smaller so they can squeeze between the pulses of the microwave." Interference from other devices operating in the 2.4-GHz band could cause a degradation in performance from 15% to 30%, said Haagh.

Mike Francini, director of the wireless LAN business unit at San Jose-based Cisco Systems Inc., recommended that corporate IT managers hire a radio frequency consultant before installing a wireless network; Cisco offers such consulting services as part of its wireless LAN offerings.

Adopting a "defensive" strategy before installation should help manage problems, Francini said.

Dewayne Hendricks, CEO of Dandin Group Ltd. in Fremont, Calif., serves on a Federal Communications Commission advisory group that's looking into interference on the 2.4-GHz band.

Hendricks said he believes that crowding will become so severe within a short period of time that 2.4 GHz "will only work outside of urban areas. . . . The FCC is getting complaints about interference, and this is a real issue today."


Copyright © 2000 IDG Communications, Inc.

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