Current and next generations of wireless devices and services are substantially different than the original cellular phones which could only carry voice signals. Third/fourth generation cellular and wireless local area networks are designed to support data services, image and video communications as well as voice. Multimedia signals require higher data rates and larger bandwidths than their voice counterparts. This necessitates a more efficient use of already scarce radio resources. Furthermore, guaranteeing a desired level of signal quality for image and video, measured in terms of overall distortion, is especially difficult given that the wireless channel is unreliable and most efficient compression algorithms involve error propagation.
In order to provide robust wireless multimedia communications, this research uses cooperative communication techniques along with jointly optimized source compression and channel coding strategies. Cooperation of wireless terminals is achieved by overhearing other terminal's signals and retransmitting towards the desired destination. This provides signal diversity and enables robust source-to-destination routes which can adapt to changes in the wireless environment. In order to establish the theory and practice of cooperative source and channel coding, the research plan consists of three interrelated components: Information theory of source channel cooperation; design of cooperative source and channel coding techniques with numerical/simulation studies to jointly optimize the parameters; and application of these techniques to wireless video transmission.
