Soft-output M-algorithm for concatenation of detecting and decoding

In this paper, we investigated a reduced-search soft-output detection algorithm, the soft-output M-algorithm (SO-M-algorithm), which retains only M of the largest state values during the recursions of the maximum a posteriori probability (MAP) algorithm. SO-M-algorithm is applied to concatenation of detecting and decoding where interleaved 8PSK trellis coded modulation (TCM) is used. Error rate performance of the SO-M-algorithm is simulated for terrestrial mobile multi-path fading channels and compared with that of the reduced-state soft-output detection algorithm with the same complexity and that of the hard-output detection algorithm with channel state information (CSI).