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AssigneeNihon University
InventorsMasayoshi Tanaka, Takuya Eguchi
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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(=22N)−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.
A multi-level modulation/demodulation method, wherein N (integer equal to or above 3) quadri-phase shift keying (QPSK) outputs having different amplitude levels, i.e., r2=r1·2−(i-31 1), i=2 . . . N with respect to a maximum amplitude level r1 are superposed after power amplification to form M(=22N)−valued/quadrature amplitude modulation (QAM), and N-1 outputs si of the respective executions of quadri-phase shift keying QPSK-i (i=2 to N) except the quadri-phase shift keying QPSK-1 having the maximum amplitude r1 are subjected to power amplification at the time of this formation, then the outputs are combined by a directional coupler having N-1 input terminals and one output terminal 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 multi-level modulation/demodulation apparatus comprising:
A multi-level modulation/demodulation apparatus, wherein an output having the highest level of outputs of a plurality of executions of quadri-phase shift keying (QPSK) is divided by a power division circuit and then amplified by a power amplifier to be fed to an antenna element, and the outputs other than the output having the highest level are combined, then divided by the power division circuit, and amplified by the power amplifier to be fed to the antenna element.
Dependencies are inferred from the claim text.