Soft Decoding of a Block Codeword by A* Algorithm

C.L. Ho (Taiwan)

Keywords

Soft block decoding, A* Algorithm, Branch-and-Bound (B&B), Systematic generator matrix.

Abstract

The A* decoding algorithm is efficiently applied to decode a block codeword used in a communication system. It utilizes a decision tree to partition possible solutions into sets. The metric is derived by using the A* algorithm, which lies in judiciously choosing a heuristic function. The heuristic codeword obtained by using the hard decision is conveniently used for evaluating the metric, which only involves comparison and accumulation of traversed metric. By arranging the received samples in reliability order, the search can end in quite a few stages and a large portion of tree branches can be pruned in the early stage.

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