Mitsubishi Electric shows 802.15-based location system

Researchers at Mitsubishi Electric have developed a location finding and ranging system based on an emerging short-range wireless technology.

The system is capable of determining the location of an object to an accuracy of 15 centimeters over a distance of up to 30 meters and uses the IEEE802.15.4a ultra wideband (UWB) technology that's approaching in the final stages of standardization. It could be used in a hospital, for example, where sensors continuously monitor patients and alert doctors to any problems. The doctors could be sent directly to wherever the patient is in the hospital.

The research was presented on Thursday at Mitsubishi Electric's R&D Center here, but the development work has been going on at Mitsubishi Electric Research Laboratories in Cambridge, Massachusetts, in the U.S.

The location of an object is found through triangulation, said Jin Zhang, group manager of the digital communication and networking technology lab, at the U.S. research center.

This involves measuring the time it takes a transmitted signal to be picked up by several receivers. By comparing the time difference between at least three radios -- the location of which is fixed -- the location of the transmitter can be determined within a two dimensional space, such as the floor of a building or warehouse. It can also work for a three dimensional space with the addition of a fourth fixed receiver, said Zhang.

The IEEE802.15.4a standard on which the system operates is being developed for just such ranging and location services with the added ability to transmit high-speed data at low power. Communication should be possible at speeds of between 100Kbps and 26Mbps using the technology, said Zhang. The company's prototype system is currently working at the lower speed.

With the location finding and data aspects combined it makes possible a system whereby sensors can communicate between themselves and also with a base computer. Should the sensors alert to something that needs human intervention their location can quickly be determined even if they are part of a mobile device, she said.

"The specification is almost finished and will be published in the summer," said Zhang. "After the specification is complete we'll finalize our design. The next step is chip design and system design.

She anticipates the publication of the standard will spur Mitsubishi Electric and a handful of competitors to begin working on semiconductors based on the technology. The first commercial products could follow within a year or two.