Patent ID: 8705656

Claim:
A transmission apparatus comprising: (a) a plurality of orthogonal frequency division multiplexing (OFDM) modulation signal generators configured to: (i) generate a first OFDM modulation signal by: inserting a first symbol for demodulation in a first plurality of sub-carriers at a first time and in a second plurality of sub-carriers at a second time; inserting a symbol, having both an in-phase (I) component and a quadrature-phase (Q) component in an I-Q plane of zero, in the second plurality of sub-carriers at the first time and in the first plurality of sub-carriers at the second time; and (ii) generate a second OFDM modulation signal by: inserting a symbol, having both an in-phase (I) component and a quadrature-phase (Q) component in the I-Q plane of zero, in the first plurality of sub-carriers at the first time and in the second plurality of sub-carriers at the second time; and inserting a second symbol for demodulation in the second plurality of sub-carriers at the first time and in the first plurality of sub-carriers at the second time; and (b) a transmitter configured to transmit the first OFDM modulation signal from a first antenna and the second OFDM modulation signal from a second antenna, in an identical frequency band.