Viterbi decoder design and performance evaluation for mobile satellite fading channels

Abstract

The performance of a modified Viterbi decoding scheme which applies channel state information is examined for a rate-1/2, K=7 convolutional code in the Rician fading channel with direct-to-multiple-signal power C/M=7 dB. About 1-dB improvement is obtained at a 10/sup -6/ bit error rate compared to a conventional Viterbi decoding scheme. A hardware structure that is realizable by a conventional Viterbi decoder chip is proposed for the modified scheme. It is shown that a traceback length 11 times the code constraint length for such a fading channel provides the optimal result of an additional 0.3-dB gain compared to the optimal additive white Gaussian noise (AWGN) traceback length of five constraint lengths. >