| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize a turbo decoder based on a decoding method having performance higher than that of a conventional soft judgment viterbi decoder as a style suitable for a mobile information terminal such as a portable telephone. SOLUTION: The turbo decoder is provided with a 1st received signal memory 101 storing information series, a 2nd received signal memory 102 storing 1st and 2nd parity series, a-priori memories 103-1, 103-2 for storing external information/previous information for repeating processing, an adder 104 for adding the information series to the previous information, and a selector 105 for selecting the 1st and 2nd parity series. Four results, i.e., an added result including reversed polarity, a selected result including reversed polarity, an added result between the added result and the selected result, and zero, are individually selected by four kinds of 2nd selectors on the basis of the polarity of the operation result of the adder 104 and the polarity of a selection output from the selector 105 and alpha and beta metric are operated on the basis of respective outputs from these 2nd selectors.</p> |
