| 摘要 |
PROBLEM TO BE SOLVED: To maintain the natural performance of MAP decoding, without impairing the transmission efficiency in a MAP decoder for MAP decoding of the encoded signal. SOLUTION: A transition probability calculating means 3 calculates the transition probability of a state, based on the encoded signal; a forward-direction route probability calculating means 4 calculates forward-direction route probability, based on the calculated transition probability; a final state detecting means 5 detects the state where the forward direction route probability at the final point becomes maximum, based on the calculated forward direction route probability; a backward-direction initial value setting means 6 calculates the backward-direction route probability, based on the preset initial value under the condition that the initial value of backward direction route probability for the detected state be set to 1, while the initial value of backward-direction route probability for the other state is set to 0; and the signal-detecting means 7, 8 detect the signals, before encoding for the signal encoded on the basis of the transition probability, forward-direction route probability, and backward-direction route probability. COPYRIGHT: (C)2009,JPO&INPIT
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