An electronic apparatus configured to transmit orthogonal frequency division multiplexing (OFDM) signals via subcarriers, comprising: a first antenna; a second antenna; an IFFT unit (107a, 107b) and a subcarrier insertion unit configured to generate first pilot signals Pa(i, j) to be transmitted via four pilot subcarriers of the subcarriers from the first antenna and second pilot signals Pb(i, j) to be transmitted via the four pilot subcarriers from the second antenna, wherein the first pilot signals Pa(i, j) are expressed by a product of a pseudorandom noise sequence PN(i) and first polarity data Sa(j), and the second pilot signals Pb(i, j) are expressed by a product of the pseudorandom noise sequence PN(i) and second polarity data Sb(j), where i is a symbol number in a time domain, and j is a pilot subcarrier number in a frequency domain, the first polarity data Sa(j) representing polarities of the first pilot signals Pa(i, j) provide a first vector and the second polarity data Sb(j) representing polarities of the second pilot signals Pb(i, j) provide a second vector and the first vector and the second vector are orthogonal, the subcarrier insertion unit is configured to output first data signals to be transmitted via data subcarriers of the subcarriers from the first antenna and the second data signals to be transmitted via data subcarriers of the subcarriers from the second antenna, wherein the IFFT unit (107a, 107b) is coupled to the first antenna and the second antenna and configured to perform an inverse fast fourier transform on the first data signals, the second data signals, the first pilot signals Pa(i, j), and the second pilot signals Pb(i, j).wherein the first data signals and the first pilot signals are transmitted via the first antenna and the second data signals and the second pilot signals are transmitted via the second antenna. a first antenna; a second antenna; an IFFT unit (107a, 107b) and a subcarrier insertion unit configured to generate first pilot signals Pa(i, j) to be transmitted via four pilot subcarriers of the subcarriers from the first antenna and second pilot signals Pb(i, j) to be transmitted via the four pilot subcarriers from the second antenna, wherein the first pilot signals Pa(i, j) are expressed by a product of a pseudorandom noise sequence PN(i) and first polarity data Sa(j), and the second pilot signals Pb(i, j) are expressed by a product of the pseudorandom noise sequence PN(i) and second polarity data Sb(j), where i is a symbol number in a time domain, and j is a pilot subcarrier number in a frequency domain, the first polarity data Sa(j) representing polarities of the first pilot signals Pa(i, j) provide a first vector and the second polarity data Sb(j) representing polarities of the second pilot signals Pb(i, j) provide a second vector and the first vector and the second vector are orthogonal, the subcarrier insertion unit is configured to output first data signals to be transmitted via data subcarriers of the subcarriers from the first antenna and the second data signals to be transmitted via data subcarriers of the first pilot signals Pa(i, j) are expressed by a product of a pseudorandom noise sequence PN(i) and first polarity data Sa(j), and the second pilot signals Pb(i, j) are expressed by a product of the pseudorandom noise sequence PN(i) and second polarity data Sb(j), where i is a symbol number in a time domain, and j is a pilot subcarrier number in a frequency domain, the first polarity data Sa(j) representing polarities of the first pilot signals Pa(i, j) provide a first vector and the second polarity data Sb(j) representing polarities of the second pilot signals Pb(i, j) provide a second vector and the first vector and the second vector are orthogonal, the subcarrier insertion unit is configured to output first data signals to be transmitted via data subcarriers of the subcarriers from the first antenna and the second data signals to be transmitted via data subcarriers of the subcarriers from the second antenna, wherein the IFFT unit (107a, 107b) is coupled to the first antenna and the second antenna and configured to perform an inverse fast fourier transform on the first data signals, the second data signals, the first pilot signals Pa(i, j), and the second pilot signals Pb(i, j).wherein the first data signals and the first pilot signals are transmitted via the first antenna and the second data signals and the second pilot signals are transmitted via the second antenna.