On SOVA for nonbinary codes

For binary codes, Fossorier et al. (1998), have shown that the soft-output Viterbi algorithm (SOVA) becomes equivalent to the max-log-maximum a posteriori (MAP) algorithm after a modification. In this letter, such modified SOVA is generalized into nonbinary cases. The equivalence between the modified SOVA and the max-log-MAP algorithm is proved more straightforwardly. The modified SOVA requires only add-compare-select operations and is suitable for high-speed parallel implementation.

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