Performance of M-algorithm MLSE equalizers in frequency-selective fading mobile radio channels

The performance loss of an adaptive M-algorithm maximum likelihood sequence estimation (MLSE) equalizer system is presented for frequency-selective fading mobile ratio channels, assuming a two-ray and a six-ray multipath fading model. The use of a computer simulation of a time division multiple access (TDMA) digital mobile radio link demonstrates that the M-algorithm can be substituted for the optimum Viterbi algorithm in adaptive MLSE equalizers for frequency-selective fading mobile radio channels. For a two-ray channel model, the degradation due to the use of the M-algorithm is less than 1 dB if the number M of evolved paths is 2 or larger. For channels with a heavy multipath propagation, such as the six-ray channel, the M-algorithm MLSE equalizer suffers from a considerable degradation