SOFT DECISION OUTPUT DECODER FOR CONVOLUTION CODING

摘要

PROBLEM TO BE SOLVED: To provide a soft decision output decoder for convolution coding that decodes a signal expressed in a grating with a block length N divided into windows with a length of L. SOLUTION: The decoding of a signal expressed in a grating with a block length N divided into windows having a length of L includes a step (206) where reverse recursions from a point P after the last window to the last window are reversely decoded and a point is selected for the point P at a distance sufficiently apart from the last window so that the reverse recursions decides a known state metric at the last window. The decoding also includes a step (208) where the signal is expressed in the window from the known state in the last window until the start point of the window reversely by using the reverse recursions to decide a reverse recursion state metric set to be stored, a step where a known state in the first window is decoded until the last point of the window forwardly by using the forward recursions, and a step (212) where a soft output in each stage of the forward recursions is calculated by using the reverse recursion state metric to be stored and a branch metric in each stage to provide the soft output of each stage.