AdaptiveSpace-TimeReduced-RankInterference Suppression for Asynchronous DS-CDMA based on a Diversity-Combined Decimation and Interpolation Scheme

An adaptive low-complexity space-time reduced-rank processor is proposed for interference suppression in asynchronous DS-CDMA systems based on a diversity-combined decimation and interpolation method. The novel design approach for the processor employs an iterative procedure to jointly optimize the interpolation, decimation and estimation tasks for reduced-rank parameter estimation. We describe joint iterative least squares (LS) design parameter estimators, propose alternative decimation structures, including the optimal decimation scheme, and develop low complexity adaptive recursive least squares (RLS) algorithms for the proposed structure. Linear space-time receivers with antenna arrays based on the proposed reduced-rank processor are presented and investigated for mitigating multi-access interference (MAI) and intersymbol interference (ISI) in an asynchronous DS-CDMA system uplink scenario.