Viterbi decoding apparatus and viterbi decoding method

A Viterbi decoding method, comprising:

• a) performing a Viterbi decoding process on input data to generate a set of main decoded results;
• b) performing a convolutional encoding process on the set of main decoded results to generate a set of re-encoded results;
• c) adjusting the input data to generate adjusted input data corresponding to a predetermined path in a Viterbi trellis diagram;
• d) generating a plurality of symbols according to the adjusted input data;
• and
• e) generating a set of secondary decoded results according to the plurality of symbols and the set of main decoded results
• wherein the step of generating the plurality of symbols comprises:
• selecting a survival path, which is traced back from a plurality of nodes of the predetermined path and different from the predetermined path, and for each of the plurality of nodes, calculating an accumulated branch metric difference from the selected survival path and the predetermined path to that node to accordingly generate the plurality of symbols, and
• wherein step (d) comprises:
• storing a plurality of symbol records and a metric index corresponding to each of the plurality of symbol records;
• receiving a latest accumulated branch metric difference, and comparing the latest accumulated branch metric difference with a currently recorded metric index;
• when it is determined that the latest accumulated branch metric difference is better than the currently recorded metric index, updating the currently recorded symbol record and metric index according to the latest accumulated branch metric difference and the corresponding survival path;
• determining whether to establish a new symbol record and a metric index corresponding to the symbol record;
• and
• when it is determined that the new symbol record and the metric index corresponding to the new symbol record are to be established, establishing the new symbol record and the metric index corresponding to the new symbol record according to the latest accumulated branch metric difference and the corresponding survival path.