Ultrawide band communication could lead next wave in image transmission

A new wireless technology may transform the way diagnostic images and other medical data will be managed in the future, according to proponents. Ultrawide band communication may enable uncompressed digital images to be downloaded in near-perfect security many times faster than is possible with available technology.

First developed in the 1960s for the U.S. military, UWB was classified for more than 30 years. Now it is being touted as the next wave in wireless communications. The Federal Communications Commission approved UWB for commercial use last February.

UWB expands what was once thought to be a finite number of available communications frequencies. It operates by emitting a series of extremely short electrical pulses (billionths of a second or shorter) that exist not on any particular frequency, but on all frequencies simultaneously. Some have called this a blast of electrical noise.

By dividing information into these tiny pulses instead of continuous sine waves, transmission becomes less vulnerable to interruption. Not only can UWB devices carry more information - faster and over a wider spectrum - they can transmit through walls.

The narrower the pulse, the more widely spread the signal, reducing the potential for interference from other frequencies. The key to turning UWB into communication lies in the timing of the pulses, said Bert Dugal, president of Parco Merged Media of Portland, ME, believed to be the first company to develop commercial UWB systems.

"In order to hear the information in each series, a UWB receiver has to know the exact pulse sequence used by the transmitter," he said. "Therefore, with UWB you have to know exactly when to listen in order to receive data, which makes it is all but impossible to intercept the signals."

UWB technology thus inherently protects the sharing of confidential information across the enterprise, according to Dugal. Another attractive feature is its speed: UWB can transmit data at a sustained minimum of 20 Mb per second, a number expected to grow.

While UWB can be used to locate people in earthquake rubble and to detect oncoming cars for collision avoidance, Parco plans to use it to transmit images and track medical equipment, personnel, and patients throughout the enterprise.

Low cost and UWB technology's ability to 'see' through walls are additional advantages. These features are lacking in current optical wireless networks or expensive fiber-optic cable systems.

On the downside, UWB is still a radio-frequency wireless technology, subject to the same laws of physics as all RF technologies. Tradeoffs must be made in signal-to-noise ratio versus bandwidth and range versus peak. UWB trades bandwidth for distance, so longer links (1-km limit) are slower.