Patent ID: 7809078

Claim:
An orthogonal frequency domain multiplexing (OFDM) modulator, comprising: a quadrature amplitude modulation (QAM) modulator for performing primary conversion of transmit data supplied as serial data; a serial to parallel converter for blocking a complex symbol signal sequence outputted from the QAM modulator for each set of a predetermined number of complex symbols and outputting them as parallel complex symbol signals; a subcarrier mapping unit for mapping each of the complex symbol signals outputted from the serial to parallel converter into one of a plurality of subcarriers whose frequencies are mutually different based on subcarrier map information M; an inverse fast Fourier transform (IFFT) unit for performing an inverse fast Fourier transform on the complex symbols outputted from the subcarrier mapping unit and outputting it serially as a complex signal X 1 ; a guard interval insertion unit for adding a cyclic prefix acting as a guard interval to the complex signal X 1 and performing window processing; and a parallel to serial converter for converting an output of the guard interval insertion unit into a serial signal; wherein the OFDM modulator further includes a peak factor reduction unit for converting the complex signal X 1 into a complex signal X 2 with a reduced peak factor based on the subcarrier map information M, being located between the IFFT unit and the guard interval insertion unit, wherein the guard interval insertion unit is configured to add a cyclic prefix to the complex signal X 2 with a reduced peak factor and perform the window processing, wherein the subcarrier map information M specifies a frequency of a transmit subcarrier that should transmit a complex symbol generated by the QAM modulator and a frequency of a stop wave subcarrier that does not contain an effective complex symbol, and wherein the peak factor reduction unit converts the complex signal X 1 into the complex signal X 2 with a reduced peak factor based on a complex exponential function matrix B that corresponds to the transmit subcarrier frequencies generated based on the subcarrier map information M.