Space-time iterative and multistage receiver structures for CDMAmobile communication systems

摘要

We propose novel space-time multistage and iterative receivernstructures and examine their application in code division multiplenaccess (CDMA) mobile communication systems. In particular we derive annexpression for weighting coefficients in parallel interferencencancellers (PICs) in a system with a large number of users, wherendecision statistics bias is pronounced. We further examine thenparameters in this expression and show how to obtain a practical partialncancellation method that allows on-line estimation of the weightingncoefficients. In the proposed multistage PIC, the coefficients arencalculated by using only the variances of the detector outputs. We alsonexamine an iterative PIC and observe that this receiver has similarnlimitations as the multistage PIC. The application of the novel parallelninterference cancellation strategy in the iterative receiver structurenresults in a spectacular system capacity improvement with a negligiblencomplexity increase relative to the standard iterative receiver. Thenperformance of the proposed receivers is further enhanced by receivernadaptive array antennas and space-time processing