A Diversity-Embedding Approach for High-Rate Reliable Multimedia Wireless Communications

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There is a fundamental tradeoff between rate and reliability (diversity)in multiple-antenna wireless communications. This research views diversityas a systems resource and explores allocation of this resource to achieve adesirable rate-diversity tradeoff in multimedia wireless communications.Multimedia data is often complex and consists of various components withdifferent rate/reliability requirements. For example, a real-time datastream is a candidate to receive more diversity (protection) thannon-real-time data. Other examples include complex data streams such ascompressed video, whose various components require different levels oferror protection. Over-provisioning of diversity to one data componentwill mean the loss of rate to that and other data components, a waste ofsystem resources.The focus of this research is on the creation of a flexible poolof space-time resources rather than the design of fixedmaximum-diversity schemes. The investigators design high-rate space-time codes that have a high-diversity code embedded within them. This allows a form of wireless communications where the high-rate codeopportunistically takes advantage of good channel realizationswhile the embedded high-diversity code ensures that at least partof the information is decoded reliably. The proposeddiversity-embedding codes do not require channel knowledge at thetransmitter and outperform time-sharing schemes. Using the proposed coding scheme, each traffictype constitutes a transmission layer that operates at a suitablerate-diversity tradeoff point. The investigators explore this point of view withdesignissues, specific code constructions, and application to multimediacommunications.