Diversity for noncoherent DPSK direct-sequence CDMA over a shadowed Rician-fading satellite channel

Abstract

Spatial-diversity schemes with distributed detection combining are analysed and compared with selection and maximal-ratio for noncoherent DPSK direct-sequence CDMA (DS-CDMA) in a shadowed Rician-fading land-mobile satellite channel. To evaluate the performance of the distributed-detection combining scheme, the Chernoff upper bound on its bit error probability is employed. In the distributed-detection combining system, two schemes are considered. In the first scheme, each branch sends its temporary decision to the combiner in which the demodulated signals of individual diversity branches are independent. In the second scheme, the demodulated signals are independent when conditioned on the channel state, and the combiner collects the detection results of the branches with the channel state information. Numerical results are presented for performance comparisons between the distributed detection, selection and maximal ratio combining for the DPSK DS-CDMA under light, average and heavy shadowing.