| 摘要 |
A decoding apparatus that is capable of calculating of the likelihood information at high speed while suppressing increases in processing amount and in circuit scale. In this apparatus, in computations of the backward probability in a backward probability computing section (112), while one processing system calculates the backward probability betak from the backward probability betak+2, the other processing system calculates the backward probability betak-1 from the backward probability betak+1 in parallel. Specifically considering the case of k=1, backward probabilities beta1, and beta0 are calculated in parallel in two processing systems. The calculated backward probabilities are stored in a storage section (114) on a window basis. Further, as in the backward probability, in a forward probability computing section (113), forward probabilities alphak and alphak+1 are calculated in parallel in two processing systems. When the forward probabilities are calculated, a likelihood computing section (115) calculates the likelihood information using the forward probabilities and backward probabilities stored in storage section 114.
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