Development & Analysis of Multi-user Receivers for Multi-rate Wireless Communication

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9505881 Urbashi Mitra In order for future wireless communications networks to accommodate a variety of potentially disparate sources (voice, data and video signals), multi-rate communication schemes must be developed. Possible sources such as voice, video, and data communications have inherently different quality of service (QoS) requirements. A constant bit-rate paradigm as exists in the current wireless network will not serve such multi-rated services of the future. The principal aim of this research is to begin the analysis and development of communication receivers for multi-user spread-spectrum communications with different information rates. Several multi-rate multi-user access schemes will be considered for Direct-Sequence Spread Spectrum Code-Division Multiple-Access communications. Three activities are planned for the preliminary study. First, existing single bit rate receivers will be investigated to determine whether they are easily extensible to multi-rate communications. Second, multi-user receivers will be created to explicitly exploit the redundancy in the mixture of narrowband and wideband user signals. Third, a cost function will be developed to compare the various receivers created. Due to the nature of the signals being considered, the probability of bit detection error does not fully capture the performance of a given receiver. The ultimate goal of the proposed preliminary research is to position the applicant to perform research on the design and analysis of true variable bit rate communications (e.g. video transmissions); communications where the bit rate is changing for each individual user. In multi-rate communications each user transmits at a constant rate which may differ from user to user. It is believed that such receivers must be adaptive in nature to properly support the variable rated traffic.