A radio transmission device (110a; 110b) comprising: a known signal generating unit to generate a first known signal (130a; 130c) and a second known signal (130b; 130d), wherein for each of the first known signal and the second known signal first signals and first null signals are mapped alternately in time direction and alternately in frequency direction in such a manner that, in each of a plurality of consecutive time periods corresponding to consecutive symbols, subcarriers for transmitting the first signals of a symbol of the first known signal in the respective period of time do not overlap with subcarriers for transmitting the first signals of a symbol of the second known signal in the same period of time, the first signals being known signals and not being 0; an inverse discrete Fourier transform unit to convert each of the first known signal (130a; 130c) and the second known signal (130b; 130d) from a frequency domain signal into a time domain signal; a guard interval inserting unit to insert a guard interval into each of the first known signal (130a; 130c) and the second known signal (130b; 130d) converted into time domain signals; a first transmission antenna to transmit the first known signal (130a; 130c) in which the guard interval is inserted; and a second transmission antenna to transmit the second known signal (130b; 130d) in which the guard interval is inserted, wherein the known signal generating unit is configured to perform block coding in the time direction or the frequency direction between the first known signal (130a; 130c) and the second known signal (130b; 130d) depending on a combination of the first signals and the first null signals , before mapping. a known signal generating unit to generate a first known signal (130a; 130c) and a second known signal (130b; 130d), wherein for each of the first known signal and the second known signal first signals and first null signals are mapped alternately in time direction and alternately in frequency direction in such a manner that, in each of a plurality of consecutive time periods corresponding to consecutive symbols, subcarriers for transmitting the first signals of a symbol of the first known signal in the respective period of time do not overlap with subcarriers for transmitting the first signals of a symbol of the second known signal in the same period of time, the first signals being known signals and not being 0; an inverse discrete Fourier transform unit to convert each of the first known signal (130a; 130c) and the second known signal (130b; 130d) from a frequency domain signal into a time domain signal; a guard interval inserting unit to insert a guard interval into each of the first known signal (130a; 130c) and the second known signal (130b; 130d) converted into time domain signals; a first transmission antenna to transmit the first known signal (130a; 130c) in which the guard interval is inserted; and a second transmission antenna to transmit the second known signal (130b; 130d) in which the guard interval is inserted, wherein the known signal generating unit is configured to perform block coding in the time direction or the frequency direction between the first known signal (130a; 130c) and the second known signal (130b; 130d) depending on a combination of the first signals and the first null signals , before mapping. <EOS>