MULTI-VALUE MODULATION/DEMODULATION METHOD AND MULTI-VALUE MODULATION/DEMODULATION DEVICE

Multi-level modulation that is hardly affected by non-linear characteristics of a power amplifier and is equal to or above 64-valued quadrature amplitude modulation (64-QAM) is provided. N (integer equal to or above 3) quadri-phase shift keying (QPSK) outputs having different amplitude levels, i.e., r2=r1·2 -(i-1) , i=2 ... N with respect to a maximum amplitude level r1 are superposed after power amplification to form M(=2 2N )-valued/quadrature amplitude modulation (QAM), and N-1 outputs si except the quadri-phase shift keying QPSK-1 having the maximum amplitude r1 are subjected to power amplification in this formation, then the outputs are combined by a directional coupler to obtain a combined signal, and an output of the quadri-phase shift keying QPSK-1 and the combined signal are transmitted from two systems of antennas to be vectorially superposed and combined in a space. A series/parallel converter is provided before each QPSK unit to divide and input input data of 2N bits, and a variable gain unit and a variable phase shifter adjust a gain and a phase.