Soft-decision Viterbi decoding with diversity combining mobilesatellite communications

摘要

Diversity combining methods for convolutional coded andsoft-decision Viterbi decoded channels in mobile satellite communicationsystems are evaluated. Computer simulations confirm that thepre-Viterbi-decoding maximal-ratio combining method has betterperformance than other methods in Rician fading channels. Bit errorprobability performances derived from the analysis model using theprobability density function of Rician fading and the bit errorprobability performance of Viterbi decoding in additive white Gaussiannoise (AWGN) channels are shown to agree with the simulation results.The diversity method is applied to trellis-coded 8PSK modulation andcoherent detection/differential detection, and their performances arecompared with conventional QPSK modulation and coherent detection withhigh-coding-rate and high-coding-gain Viterbi decoding. QPSK withhigh-coding-rate Viterbi decoding can be an attractive candidate formobile satellite systems as well as trellis-coded 8PSK