Multiuser diversity receivers for frequency-selective Rayleigh fading CDMA channels

Adaptive receiver structures for coherent and differentially coherent multiuser detection with diversity combining in the frequency-selective Rayleigh fading CDMA channels are proposed. The receiver employs a recursive-least-squares (RLS) multipath MMSE filter-bank at the front-end to mitigate the multiple-access interference and the multipath interference. Two suboptimal schemes for joint channel estimation and symbol detection are developed, namely, the decision-directed symbol-by-symbol detection and the per-survivor sequence detection. A differentially coherent detection scheme is also considered. Finally, the performance of these adaptive detectors are assessed by simulations. A salient feature of the adaptive receivers proposed in this paper is that their implementations can be mapped to VLSI systolic arrays to exploit massively parallel signal processing computation.