Decoding method and decoding device

A decoding device of decoding N received branchwords produced by a convolutional encoder using a tail-biting convolutional code, comprising:

• a memory storing the N received branchwords;
• and
• a data processing unit comprising:
• a successive performing unit which successively performs Viterbi updates on a sequence of branchwords, the sequence comprising a first block comprising S consecutive branchwords from the N received branchwords, a second block comprising the N received branchwords and a third block comprising T consecutive branchwords from the N received branchwords, where S and T are less than N, and where the Viterbi updates generate updated path metrics;
• a determining unit which determines a first encoder state at the end of the third block most likely to have generated the final branchword in the sequence from the best path metric;
• a first performing unit which performs a Viterbi traceback procedure from that first encoder state at the end of the third block to determine a second encoder state at the start of the third block of branchwords;
• a second performing unit which performs a Viterbi traceback procedure from that second encoder state at the start of the third block to determine a third encoder state at the start of the second block of branchwords;
• and
• an outputting unit which outputs a derived tail-biting path, if the second and third encoder states are identical.