AN ADAPTIVE SOFT-OUTPUT VITERBI EQUALIZER FOR FAST TIME-VARYING FREQUENCY-SELECTIVE FADING

In this paper, an adaptive soft-output Viterbi equalizer (SOVE) is pro posed for fast time-varying frequency-selective fading. The demodulato r can make a symbol-by-symbol or bit-by-bit soft-decision based on a p osteriori probabilities. The proposed adaptive SOVE has the following advantages: (1) it has a superior tracking ability for fast time-varyi ng frequency-selective fading, (2) it works in blind if the coding rul es are suitably designed, and (3) a good BER is obtained at the output of the decoder by introducing interleaves. In this paper, these advan tages are confirmed by computer simulations. In particular, in the pre sence of frequency-selective fading, we can show that the proposed met hod is superior to adaptive maximum-likelihood sequence estimation whi ch carries equalizing and decoding simultaneously. (C) 1998 Scripta Te chnica.