Wireless communications system, wireless communications method, and wireless communications apparatus

A wireless communications system taking account of a transfer function of a communications channel between a transmitter and a receiver each having an antenna, the system comprising:

• a calibration coefficient obtainer which obtains a calibration coefficient for each of the antennas of the transmitter and the receiver by calculating a ratio of a transfer function of each of a transmission circuit and a reception circuit corresponding to each of the antennas;
• a reference signal feedback unit which feeds back a reference signal as compensated on the part of the receiver by using the calibration coefficient for the antenna of the receiver, to the transmitter;
• a transfer function calculator which compensates, on the part of the transmitter, the received calibrated reference signal by using the calibration coefficient for the antenna of the transmitter, and obtains a transfer function based on the compensated reference signal;
• and
• a data sender which transmits data using the transfer function.

A wireless communications method for a communication between a transmitter and a receiver each having a plurality of antennas, over a communications channel by multiplexing a signal, the method comprising:

• feeding back reference signals for respective antennas of the receiver from the receiver to the transmitter;
• calculating, based on the reference signals received by the transmitter, a channel information matrix H whose elements represent transfer functions of respective communication sub-channels of the channel each of which links one of the antennas of the transmitter and one of the antennas of the receiver;
• performing a singular value decomposition of the channel information matrix H to yield UDVH, so as to obtain a transmit antenna weighting coefficient matrix V whose entries represent weighting vectors for the respective antennas of the transmitter;
• sending the components of a reference signal from the respective antennas of the transmitter to the receiver with the components weighted by the transmit antenna weighting coefficient matrix V;
• calculating, based on the weighted reference signals received by the receiver, a channel information matrix H′ corresponding to the transmit antenna weighting coefficient matrix and respective antennas of the receiver;
• determining a receive antenna weighting coefficient matrix based on the channel information matrix H′;
• and
• decoding a signal received after obtaining the receive antenna weighting coefficient matrix based on the received antenna weighting coefficient matrix.

A wireless communications method taking account of a transfer function of a communications channel between a transmitter and a receiver each having an antenna, the method comprising steps of:

• obtaining a calibration coefficient for each of the antennas of the transmitter and the receiver by calculating a ratio of a transfer function of each of a transmission circuit and a reception circuit corresponding to each of the antennas;
• feeding back a reference signal as compensated on the part of the receiver by using the calibration coefficient for the antenna of the receiver, to the transmitter;
• compensating, on the part of the transmitter, the received calibrated reference signal by using the calibration coefficient for the antenna of the transmitter, and obtaining a transfer function based on the compensated reference signal;
• and
• sending data using the transfer function.