Subtrellises for low-weight codewords of binary linear block codes have been recently used in a number of trellis-based decodingalgorithms to achieve near-optimum or suboptimum error performance with a significant re...
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Subtrellises for low-weight codewords of binary linear block codes have been recently used in a number of trellis-based decodingalgorithms to achieve near-optimum or suboptimum error performance with a significant reduction in decoding complexity. An algorithm for purging a full code trellis to obtain a low-weight subtrellis has been proposed by H.T. Moorthy el. al. This algorithm is effective for codes of short to medium lengths, however for long codes, it becomes very time consuming. This paper investigates the structure and complexity of low-weight subtrellises for binary linear block codes. A construction method for these subtrellises is presented. The state and branch complexities of low-weight subtrellises for Reed-Muller codes and some extended BCH codes are given. In addition, a recursivealgorithm for searching the most likely codeword in low-weight subtrellis-based decodingalgorithm is proposed. This recursivealgorithm is more efficient than the conventional Viterbi algorithm.
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