| 摘要 |
PROBLEM TO BE SOLVED: To provide a decoder which shortens the decoding execution time, when a transmission codeword is decoded based on the maximum posteriori probability decoding method, and to provide decoding method and program.SOLUTION: When decoding a transmission codeword from a received codeword based on the maximum posteriori probability decoding method, a decoder 10 normalizes 1/2 of the sum of a communication path value, i.e., an argument of a hyperbolic function, and a prior value, instead of calculating an external value by using a hyperbolic function, performs linear approximation of the hyperbolic function by 1/2 of the sum of a normalized communication path value and a prior value, and then calculates the external value by using the value subjected to linear approximation. Furthermore, the decoder 10 may perform calculation by multiplying the sum of the communication path value and prior value by the same real number, and representing by a 8-bit integer with code. Calculation of the external value is performed by any one of the linear approximation of a hyperbolic function, or integer linear approximation. |
