Patent ID: 7778339

Claim:
A transmission method comprising steps of: generating a first OFDM modulation signal and a second OFDM modulation signal, utilizing a plurality of OFDM modulation signal generators, by: inserting a symbol for demodulation in a first sub-carrier of the first OFDM modulation signal at a first time and a symbol where both of an in-phase (I) signal and a quadrature-phase (Q) signal in an I-Q plane are made to be zero in a first sub-carrier of the second OFDM modulation signal at the first time; inserting the symbol for demodulation in a second sub-carrier of the second OFDM modulation signal at the first time and the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a second sub-carrier of the first OFDM modulation signal at the first time; inserting the symbol for demodulation in a third sub-carrier of the first OFDM modulation signal at the first time and the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in an I-Q plane are made to be zero in a third sub-carrier of the second OFDM modulation signal at the first time; inserting the symbol for demodulation in a fourth sub-carrier of the second OFDM modulation signal at the first time and the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in a fourth sub-carrier of the first OFDM modulation signal at the first time; and inserting the symbol where both of an in-phase (I) signal and a quadrature-phase (Q) signal in an I-Q plane are made to be zero in the first sub-carrier of the first OFDM modulation signal at a second time and the symbol for demodulation in the first sub-carrier of the second OFDM modulation signal at the second time; inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the second sub-carrier of the second OFDM modulation signal at the second time and the symbol for demodulation in the second sub-carrier of the first OFDM modulation signal at the second time; inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in an I-Q plane are made to be zero in the third sub-carrier of the first OFDM modulation signal at the second time and the symbol for demodulation in the third sub-carrier of the second OFDM modulation signal at the second time; and inserting the symbol where both of the in-phase (I) signal and the quadrature-phase (Q) signal in the I-Q plane are made to be zero in the fourth sub-carrier of the second OFDM modulation signal at the second time and the symbol for demodulation in the fourth sub-carrier of the first OFDM modulation signal at the second time; and transmitting the first OFDM modulation signal from a first antenna and the second OFDM modulation signal from a second antenna, in an identical frequency band.