A transmission apparatus includes orthogonal frequency division multiplexing (OFDM) modulation signal generating circuitry. The circuitry generates a first OFDM modulation signal by inserting symbols for demodulation in a first plurality of subcarriers at a first time and in a second plurality of sub-carriers at a second time adjacent to the first time, the symbols for demodulation being reception processing reference symbols of a reception apparatus, and, inserting symbols, 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. The circuitry generates a second OFDM modulation signal by inserting the symbols for demodulation in the second plurality of subcarriers at the first time and in the first plurality of sub-carriers at the second time, and, inserting the symbols, having both the I component and the 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. The apparatus includes transmitting circuitry to transmit the first and the second OFDM modulation signals, from respective different antennas, in an identical frequency band.