An Adaptive Soft-Output Viterbi Equalizer for Fast Time-Varying Frequency Selective Fading

In this paper, an adaptive soft-output Viterbi equalizer (SOVE) is proposed for fast time-varying frequency-selective fading. The demodulator can make a symbol-by-symbol or bit-by-bit soft-decision based on a posteriori probabilities. The proposed adaptive SOVE has the following advantages: (1) it has a superior tracking ability for fast time-varying frequency-selective fading, (2) it works in blind if the coding rules are suitably designed, and (3) a good BER is obtained at the output of the decoder by introducing interleaves. In this paper, these advantages are confirmed by computer simulations. In particular, in the presence of frequency-selective fading, we can show that the proposed method is superior to adaptive maximum-likelihood sequence estimation which carries equalizing and decoding simultaneously. © 1998 Scripta Technica. Electron Comm Jpn Pt 1, 81(4): 31–39, 1998