Performance of an adaptive viterbi decoder employing respective‐state channel estimation

Abstract

AbstractThis paper discusses a performance of an adaptive Viterbi decoder, which performs the carrier recovery and the Viterbi decoding simultaneously. the authors have already considered the combined maximum‐likelihood sequence estimator (MLSE), according to trellis combined equalization and the Viterbi decoding and showed that the bit‐error rate in the fading environment can be improved by applying channel estimation respecitvely for states of the Viterbi algorithm. the adaptive Viterbi decodere discussed in this paper corresponds to the combined MLSE in the case of no intersymbol interference and and easily be extended to the case of the diversity reception.First, the square Euclidean distance is derived approximately by combining the channel estimation by the least mean squares (LMS) and MLSE, and it is shown that the adaptive Viterbi decoder can perform the diversity combining without carrier phase information, with only a little performance degradation compared to the ideal Viterbi decoding with known carrier phase. Then, by a computer simulation, the results of analysis and the numerical calculation are confirmed and the proposed adaptive Viterbi decoder is shown to be effective in the carrier frequency offset and fading environment.