| 摘要 |
PROBLEM TO BE SOLVED: To apply to a mobile communication system or the like and to prevent the decline of the transmission efficiency of signals by maximum likelihood estimation of a modulation index at a reception side without transmitting control signals at a transmission side especially in the case of changing the modulation index based on channel power gain. SOLUTION: For received signals 101 to which the information of the modulation index at the time of transmission is not added, respective modulation index estimation parts 102 calculate the average values or dispersion values of carrier power for the respective modulation indexes and calculate the difference of them and the reference average value or reference dispersion value of the carrier power stipulated beforehand for the respective modulation indexes as likelihood function values ΛML#1 -ΛML#X for the respective modulation indexes. A minimum likelihood function value selector 104 selects the modulation index corresponding to the likelihood function value provided with a maximum likelihood value among the likelihood function values and makes a data selector 105 select the output of a modulation index demodulation part 103 corresponding to it as demodulation signals 106. |
