9408957 Kahn Non-directed infrared radiation is a promising medium for high-capacity, short-range indoor communications. Infrared possesses several advantages over radio, including an enormous unregulated bandwidth and the fact that infrared radiation cannot pass through walls. As a result, high-speed links can operate in each room of a building without interference. There are now available commercially several infrared-based local-area networks for portable computers, which use diffuse transmission to achieve network capacities as high as 4 Mb/s per room over a range as long as 15m. The optical systems and modulation techniques used in current infrared will probably permit network capacities to be increased to about 10 Mb/s per room. Achievement of higher bit rates will require new solutions to overcome the noise induced by intense ambient infrared radiation, signal distortion due to multipath propagation, and interference from other users. The project will investigate components and techniques to enhance the performance of non-directed infrared communication systems operating at bit rates for 10 to 100 Mb/s, or even higher. To provide concrete guidance, the research will address the full-duplex communication requirements of a representative application in wireless multimedia computing. This application involves simultaneous transmission of multimedia from a base station to as many as 50 portable terminals within a single room, requiring an aggregate downlink bit rate of 50 to 100 Mb/s. As the portable terminals will not source video and most computations will be performed by servers on a backbone network, uplink requirements are modest, of the order of 10 Mb/s per room. For this application, it is desirable minimize the complexity and power consumption of the portable infrared transceivers, at the possible expense of increased of increased base-station power consumption and complexity. The research will encompass transmitter and receiver optical design, theoretical performance s tudies of modulation and detection techniques in the single-and multi-user environment, and experimental demonstration of full-duplex communication between a base station and portables. The first two years of activity will focus on study of key components and communication techniques, and with the third year devoted to constructing a prototype link incorporating the optimized components and techniques ***
