Wireless communication method, wireless communication system, and transmission device

1 . A wireless communication method for performing wireless communication between a transmission device and a reception device,

the wireless communication method comprising:

phase shift amount determination processing that determines a random phase shift amount for each of subcarriers of transmission data;

signal addition processing that adds a known signal, which is to be used in the reception device for estimating the random phase shift amount, to the transmission data;

modulation processing that modulates the transmission data and further shifts a phase according to the random phase shift amount for each of the subcarriers;

precoding processing that performs precoding on the transmission data after the modulation processing; and

transmission processing that transmits the transmission data after the precoding processing from the transmission device to the reception device, wherein

the signal addition processing is performed for each predetermined data unit that a slot, and

the signal addition processing adds the known signal to a head or end of the predetermined data unit.

2 . The wireless communication method according to claim 1 , wherein

the phase shift amount determination processing includes:

acquiring a phase shift pattern indicating a random sequence of the phase shift amount; and

determining the random phase shift amount for each of the subcarriers by repeatedly applying the random sequence every predetermined number of subcarriers.

3 . The wireless communication method according to claim 1 , wherein

the phase shift amount determination processing includes:

acquiring a plurality of types of phase shift patterns each indicating a random sequence of the phase shift amount;

selecting, from among the plurality of types of phase shift patterns, one that minimizes a peak to average power ratio (PAPR) of the transmission data after the precoding processing or one that maximizes a reception quality of the transmission data in the reception device; and

determining the random phase shift amount for each of the subcarriers based on the random sequence indicated by the selected phase shift pattern.

4 . The wireless communication method according to claim 1 , further comprising:

receiving, by the reception device, the transmission data transmitted from the transmission device as reception data;

estimating, by the reception device, the random phase shift amount based on the known signal; and

demodulation processing that demodulates the reception data based on the estimated phase shift amount.

5 . A wireless communication system comprising:

a transmission device; and

a reception device, wherein

the transmission device is configured to execute:

phase shift amount determination processing that determines a random phase shift amount for each of subcarriers of transmission data;

signal addition processing that adds a known signal, which is to be used in the reception device for estimating the random phase shift amount, to the transmission data;

modulation processing that modulates the transmission data and further shifts a phase according to the random phase shift amount for each of the subcarriers;

precoding processing that performs precoding on the transmission data after the modulation processing; and

transmission processing that transmits the transmission data after the precoding processing from the transmission device to the reception device, wherein

the signal addition processing is performed for each predetermined data unit that a slot, and

the signal addition processing adds the known signal to head or end of the predetermined data unit.

6 . The wireless communication system according to claim 5 , wherein

the reception device is configured to:

receive the transmission data transmitted from the transmission device as reception data;

estimate the random phase shift amount based on the known signal; and

demodulate the reception data based on the estimated phase shift amount.

7 . A transmission device that performs wireless communication with a reception device,

the transmission device comprising processing circuitry configured to:

determine a random phase shift amount for each of subcarriers of transmission data;

add a known signal, which is to be used in the reception device for estimating the random phase shift amount, to the transmission data;

modulate the transmission data and further shift a phase according to the random phase shift amount for each of the subcarriers;

perform precoding on the transmission data after modulation; and

transmit the transmission data after the precoding to the reception device, wherein

the addition of the known signal is performed for each predetermined data unit a slot, and

the known signal is added to head or end of the predetermined data unit.