Distance Threshold Viterbi Decoding of Convolutional Codes

This work introduces a reduced complexity Viterbi decoding algorithm for convolutional codes. Since the guaranteed error correcting capability is determined by the minimum free distance of the convolutional code, the proposed algorithm will use the free distance threshold as an elimination rule at each state. This discarding threshold is simple in a sense that it does not need updating from one trellis time index to another. The proposed algorithm yields almost the same error performance as the Viterbi algorithm while requiring a substantially smaller average number of computations. Nonetheless, the proposed algorithm has inherent flexibility such that a good compromise between complexity reduction and error performance is fulfilled.