The Wireless Information Technology Lab (http://witlab.ee.ucr.edu/) led by Professor Zhengyuan Xu has received a $250K DoD grant for “Instrumentation for Multiuser Non-Line of Sight Optical Communications”. This grant will supplement existing support from the ARO and ARL on relevant fundamental research and past DoD support on building a single-user ultraviolet (UV) communication experimental testbed (see picture below). This one-year grant will be designated to developing an in-depth experimental study of multiuser UV communication under non-line-of-sight (NLOS) channel conditions. Measurement results based on the new multiuser testbed will provide a foundation for novel analytical studies of UV channel modeling, NLOS communication system theory, and networking.  Optical communication in the deep UV wavelength spectral band (200-280nm) has several unique characteristics. Firstly, solar radiation reaching the ground is negligible in this particular band due to strong ozone absorption in the upper atmosphere, resulting in a solar-blind band with almost no solar background noise. This property is unique to UV and different from other optical bands. Secondly, atmospheric molecules and aerosols are highly scattering of optical waves in the UV band, providing abundant propagation paths for UV photons from a transmitter to a receiver. Thus an NLOS communication link can be easily established without strict pointing and tracking of transmitter/receiver that are often associated with typical line-of-sight optical communication systems. Moreover, high atmospheric absorption brings about such additional features as enhanced range-dependent system security, covertness and jamming resistance. More background information on UV communications can be found in a recently published paper Z. Xu and B. M. Sadler, “Ultraviolet communications: potential and state-of-the-art,” IEEE Communications Magazine, vol. 46, no. 5, pp. 67-73, May 2008.and at the website http://www.ee.ucr.edu/~dxu/CFP-UVworkshop08.html of the ARO/ARL Workshop on Ultraviolet Devices and Communication Systems, held on April 23, 2008 and co-organized by Professor Zhengyuan Xu.
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