Tests highlight Bluetooth/WLAN conflicts

Wireless vendors have shown that conflicts between Bluetooth devices and 802.11b Wireless Ethernet networks, while not as bad as anticipated, are still severely limiting.

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By  Jon Tullett Published  February 21, 2001

Wireless LAN research is suggesting that Bluetooth interference can cause serious degradation. EETimes reports that Symbol Technologies, which makes mobile devices such as barcode scanners, conducted tests with the Bluetooth devices and 802.11b wireless Ethernet interfaces in laptops. Although the company brushed off the results as “acceptable”, WLAN users may not agree.

However, clouds still hang over the expected rollout of Bluetooth products later this year and some notebook makers said they won't build Bluetooth into their portables until 2002.

"We've found [the contention] is just not an issue," said Barry Issberner, vice president of business development at Symbol.

In Symbol's experiment, the company set two notebook computers with Bluetooth cards from Digianswer 1 foot apart, continuously transmitting FTP files. Engineers then turned on a handheld computer with an 802.11b card that regularly "pinged" an access point set 40 feet away.

"When we got the handheld within one to three feet of the notebooks, the 802.11b network slowed down considerably, down from about 11 Mbits/s to about 1 Mbit/s," said Issberner. "But data still got through all the time. The Bluetooth connection also experienced issues, but it kept going."

One to three feet? That is easily as close as a notebook user will be positioned from his machine when operating it. If carrying a Bluetooth-enabled PDA or mobile phone is going to force a wireless LAN NIC into its lowest permitted operating mode before the connection is terminated, a lot of potential users are going to think twice.

Incidental interference is also a risk; will casual visitors to your desk cause your download to fail? Only at a range of six feet and beyond did the devices cease to interfere, Issberner reported. Despite this, he stated: "It's not a big issue."

Toshiba, which conducted similar tests, pulled support for Bluetooth from its January range of notebooks, but cited delays in chipsets supporting the newer 1.1b Bluetooth standard as the reason.

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