Soft decision decoding of Reed-Solomon codes using trellis methods

Soft decision decoding of Reed-Solomon codes has been implemented by using trellis decoding methods. Trellis decoding schemes make it possible to incorporate both hard and soft decision methods easily. To establish maximum likelihood performance, the Viterbi decoding algorithm has been used. To reduce the decoder complexity caused by full search Viterbi decoding, reduced search methods have been tried, and a computationally efficient reduced search algorithm is suggested. Importance sampling simulation techniques have been used to reduce simulation time. The simulation results for the (15, 13) and the (15, 11) Reed-Solomon code showed that soft decision trellis decoding could give 2 dB and 2.5 dB coding gains relative to hard decision, respectively, and that the performance of reduced search decoding could approximate that of the Viterbi method with reductions in computation of one to two orders of magnitude