Conflicts between Bluetooth and wireless LANs called minor

Conflicts between Bluetooth and wireless LANs called minor
By Rick Merritt, EE Times
February 21, 2001 (5:59 a.m. EST)
URL: http://www.eetimes.com/story/OEG20010220S0040

PHOENIX — Wireless Bluetooth links and 802.11b wireless LANs can clash, but the conflicts are within acceptable limits, according to tests from two systems makers. However, clouds still hang over the expected rollout of Bluetooth products later this year and some notebook makers said they will not build Bluetooth into their portables until 2002.

Symbol Technologies Inc., a maker of bar-code readers, and Toshiba Corp.'s notebook computer division reported that Bluetooth can significantly degrade performance for an 802.11b network in some instances. Their separate tests confirmed that the conflicts are not as bad as once expected, the managers said at the Mobile Insights conference here Monday (Feb. 19).

"We've just completed some tests for Avis, and we've found [the contention] is just not an issue," said Barry Issberner, vice president of business development at Symbol (Holtsville, N.Y.), which makes rugged handheld systems for vertical m arkets.

In Symbol's experiment, the company set two notebook computers with Bluetooth cards from Digianswer one 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 1 to 3 feet of the notebooks, the 802.11b network slowed down considerably, down from about 11 Mbits/second 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."

In the 3- to 6-foot range both connections experienced some degradation, though not nearly so severe. And at a range of 6 feet and beyond the two networks did not interfere, Issberner reported.

The result, he said: "It's not a big issue."

Toshiba, which provided no details on its tests, came to a similar conclusion in a recent white paper. "We saw some degradation," but the two links can run acceptably in the same area, said Steve Andler, vice president of marketing for Toshiba's notebook group.

Acceptable conflict

A Toshiba lab in Japan that handles much of the company's Bluetooth work circulated a thick report of its test work on the subject last month. Its conclusion was that the conflicts between the two links are acceptable.

"This was a big concern for the industry six months ago, and we all thought Bluetooth would blow everything out of the water," said Andler. "Intel has put a lot of research money into this area too."

That's not to say Bluetooth is completely out of the woods. Andler said his technical people at the last minute pulled built-in Bluetooth support from a line of Toshiba notebooks that shipped in January. The reason: The shift from a 1.0 to a 1.1b Bluetooth standard would require another six months of work before Toshiba would be prepared to ship such systems.

"I don't know if that will change chip sets," said Andler, "but I don't think we'll see any chip sets [supporting 1.1b] until the third quarter."

Another question that still hangs over the short-range wireless link is whether it will be adequately supported by Microsoft Corp.'s next generation of Windows, code-named Whistler. "We'll find out at WinHEC," said Andler, referring to Microsoft's hardware developers' conference scheduled for the end of March.

"One of the things that killed IrDA [an infrared data interconnect standard] was the lack of OS support," he noted.

Costs for Bluetooth chips and other components are also still quite high, Andler said. "We thought the [802.11b and Bluetooth] antennas would cost [a total of] about $5, but they wound up costing $20," he said.

Nevertheless, the Toshiba manager expressed confidence Bluetooth would eventually come to market. "There are too many people investing in Bluetooth outside the PC industry for it not to happen, even though we have a black eye from having another six-month pushout," he said.

Symbol's Issberner agreed, citing support from the automobile industry. "We learned from talking to Avis that they expect to get vehicles within 18 months that could have Bluetooth or 802.11 transceivers," he said. Those links could be used by Avis clerks to read a car's mileage, gas tank level or other key stats more quickly and accurately, he said.

Other managers here expressed similarly cautious optimism for Bluetooth. "We have Bluetooth-enabled notebooks now, but we won't have Bluetooth built into our notebooks until 2002. We want to wait until there are Bluetooth-enabled phones," said Leo Suarez, director of worldwide product marketing for IBM Mobile Systems.

Short on commitment

At a panel discussion here managers from the notebook divisions of Dell, Hewlett-Packard and Fujitsu similarly were reluctant to commit to building Bluetooth into their portables this year, though they generally expressed support for the technology.

Consultant Craig Mathias of the Farpoint Group said he thinks the last-minute standards changes, compounded by the wide diversity of chip sets in the works, could lead to possibly fatal interoperability problems for the 700-kbit/second wireless interconnect technology.

"I am still skeptical about Bluetooth," Mathias said. "Bluetooth already has one black eye for over-promising, now they may get another one for under-delivering. All it will take is for one widely respected reviewer to say this stuff doesn't work, and that could be the end of it in the consumer market."

For his part, Issberner said that Symbol continues to work with Intel to deliver as many as 85 products as part of a three-year cooperation on multimode cards that support both Bluetooth and 802.11a and -b wireless LANs. Those products include multifunction cards in a variety of formats including Compact Flash, PCMCIA, mini PCI and various kinds of embedded modules.