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By combining software with its existing chips for Wi-Fi and Bluetooth networks, Texas Instruments has found a way to limit interference between the two wireless technologies in handheld devices.

The result could be a peaceful coexistence between Bluetooth support and wireless LAN transmissions, which could be either 802.11b or the newer 802.11g. Devices that use the new TI chip will likely be available early in the fourth quarter, according to the company.

Smoothing Signals

Bluetooth and 802.11b both send their signals across the 2.4-GHz frequency, which is also used for a variety of common products like baby monitors and garage door openers. In order to use Bluetooth and 802.11b in the same device effectively, the Dallas company needs to develop software that monitors wireless traffic on a packet level to route high-priority traffic and avoid packet collisions, says Matthew Shoemake, director of advanced technology in TI's WLAN business unit.

This "coexistence" package of chips and software is designed for cell phones, smart phones and personal digital assistants, Shoemake says. It can also be used in notebook computers, but it was conceived for small, handheld devices more prone to interference problems.

Bluetooth is a short-range wireless technology that is used primarily for PC peripherals, such as keyboards, or voice connections between a cell phone or smart phone and a wireless headset. The 802.11b standard is used mainly in notebook computers for connections to the Internet or corporate networks.

Users might see a slight performance degradation in Internet connection speeds while using their Bluetooth headsets, but most probably won't even notice, Strauss says. 802.11b networks have an effective connection speed of about 6 megabits per second, which is much faster than home broadband connections. But every user would notice static or problems with the voice connection, which is why that transmission deserves priority, he said.

TI's software gives the highest priority to Bluetooth voice traffic, because customers want clear voice connections without static or dropped calls, Shoemake said. But the user doesn't notice the prioritization, and can use a Bluetooth headset while checking their e-mail on a 802.11b network without any problems, he said.

Welcome Support

"TI has been shipping millions of Bluetooth chips through Nokia cell phones and has captured a reasonable percentage of the WLAN market. They know this market well," says Will Strauss, principal analyst at market researcher Forward Concepts.

TI expects products implementing the new chip set will be generally available in the fourth quarter, but a TI customer plans to release a device with this technology in September, Shoemake says. He declines to provide further details.

The two chips and the coexistence software cost less than $20 to the device manufacturers when purchased in volume, he says. The TI product will not be available to end users directly.

Future devices with the coexistence technology might resemble the Wireless Any Network Digital Assistant (WANDA) reference design that TI showed at the CTIA show in New Orleans in March. WANDA features Bluetooth, 802.11b, and Global System for Mobile Communications/General Packet Radio Services wireless chips. Products based on the design are expected in the third or fourth quarters, the company said in March.

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