Radio communication apparatus capable of switching modulation schemes

A transmitting method, comprising:

• generating a modulation signal by modulating transmission data using one of a plurality of modulation schemes, a first modulation scheme of the plurality of modulation schemes having a higher m-ary modulation value than other modulation schemes of the plurality of modulation schemes;
• generating a pilot signal having one of a plurality of amplitudes according to a frame timing signal;
• generating an orthogonal frequency division multiplexing (OFDM) signal by selecting the modulation signal and the pilot signal according to the frame timing signal;
• converting the OFDM signal to a radio signal;
• amplifying the radio signal;
• and
• transmitting the amplified radio signal from an antenna,
• wherein the pilot signal is inserted in the OFDM signal per a predetermined OFDM symbol and per a predetermined subcarrier and has a lower amplitude than a maximum amplitude of the first modulation scheme in an in-phase-quadrature (IQ) plane.

A receiving apparatus, comprising:

• an antenna that receives a radio signal;
• an orthogonal frequency division multiplexing (OFDM) signal converter that converts the ratio signal to an OFDM signal,
• an estimator that generates a distortion estimation signal which estimates transmission path distortion using a pilot signal included in the OFDM signal;
• and
• a demodulator that corrects a distortion of the radio signal using the distortion estimation signal and demodulates transmission data, wherein:
• the OFDM signal includes a modulation signal obtained by modulating the transmission data using one of a plurality of modulation schemes and a pilot signal;
• a first modulation scheme of the plurality of modulation schemes has a higher m-ary modulation value than other modulation schemes of the plurality of modulation schemes;
• and
• the pilot signal is inserted in the OFDM signal per a predetermined OFDM symbol and per a predetermined subcarrier and has a lower amplitude than a maximum amplitude of the first modulation scheme in an in-phase-quadrature (IQ) plane.

A receiving method, comprising:

• receiving a radio signal by an antenna;
• converting the ratio signal to an orthogonal frequency division multiplexing (OFDM) signal;
• generating a distortion estimation signal which estimates transmission path distortion using a pilot signal included in the OFDM signal;
• and
• correcting a distortion of the OFDM signal using the distortion estimation signal and demodulating transmission data, wherein:
• the OFDM signal includes a modulation signal obtained by modulating the transmission data using one of a plurality of modulation schemes and a pilot signal;
• a first modulation scheme of the plurality of modulation schemes has a higher m-ary modulation value than other modulation schemes of the plurality of modulation schemes;
• and
• the pilot signal is inserted in the OFDM signal per a predetermined OFDM symbol and per a predetermined subcarrier and has a lower amplitude than a maximum amplitude of the first modulation scheme in an in-phase-quadrature (IQ) plane.