Communication system using orthogonal frequency division multiplexed signal

A communication apparatus for communicating using an orthogonal frequency division multiplexed signal, comprising:

• a transmission means for performing orthogonal frequency division multiplex modulation on a carrier in accordance with data given by an inputted signal, to transmit a multiplexed signal;
• and
• a receiving means for performing orthogonal frequency division multiplex demodulation on the received signal to detect the modulation data and for outputting the signal given by the modulation data;
• wherein said transmission means comprises:
• a data sequence conversion means for arranging first data to be transmitted, in a predetermined order corresponding to two or more sub-carriers orthogonal to each other on a frequency axis;
• a delay means for delaying said first data for a predetermined time to generate second data;
• a power changing means for changing a power spectrum of said sub-carriers in accordance with said second data;
• an inverse discrete Fourier transform means for generating a time-base waveform by synthesizing the two or more sub-carriers changed by said power changing means;
• and
• an orthogonal modulation means for performing orthogonal modulation on a real axis signal and an imaginary axis signal which are orthogonal to each other and generated by said inverse discrete Fourier transform means, to synthesize the real axis signal and the imaginary axis signal;
• and
• said receiving means comprises:
• a quadrature detection means for performing quadrature detection on the received signal to obtain a first detection axis signal and a second detection axis signal which are quadrate to each other;
• a discrete Fourier transform means for sampling respective time-base waveforms of said first detection axis signal and said second detection axis signal at a predetermined sampling frequency, and for performing discrete Fourier transform on these sampled data to obtain two or more metrics distributed in a frequency domain;
• a first data extracting means for extracting said first data from respective phase changes of sub-carriers for each symbol, obtained by said discrete Fourier transform means;
• and
• a second data extracting means for extracting said second data from an envelope of a distribution of the metrics obtained by said discrete Fourier transform means.