Transmitter, receiver, transmission method, reception method, and non-transitory computer readable storage medium for performing beamforming in wireless transmission

A receiver comprising:

• a plurality of antenna elements;
• a calibration signal generator which, in operation, generates a digital calibration signal;
• a transmission processing execution unit which, in operation, performs transmission processing including digital-to-analog conversion on the digital calibration signal to generate a first analog signal;
• a reception processing execution unit which, in operation, performs reception processing including analog-to-digital conversion on third analog signals to generate first digital signals each corresponding to respective one of the antenna elements, the third analog signals being obtained by adding the first analog signal to each of a plurality of second analog signals, the second analog signals each received via corresponding one of the antenna elements;
• a reception characteristics calculator which, in operation, performs correlation calculation between the digital calibration signal and each of the first digital signals to calculate reception delay characteristics each corresponding to respective one of the antenna elements and which, in operation, calculates reception delay correction amounts based on the reception delay characteristics, each of the reception delay correction amounts corresponding to respective one of the antenna elements;
• and
• a reception characteristics corrector which, in operation, corrects the reception delay characteristics based on the reception delay correction amounts.

A transmission method performed by a transmitter including a plurality of antenna elements, the transmission method comprising:

• generating a digital calibration signal;
• performing transmission processing including digital-to-analog conversion on second digital signals to generate first analog signals, the second digital signals being obtained by adding the digital calibration signal to each of a plurality of first digital signals, the first digital signals each corresponding to respective one of the antenna elements;
• performing reception processing including analog-to-digital conversion on the first analog signals to generate third digital signals each corresponding to respective one of the antenna elements, the first analog signals each passing through respective one of the antenna elements;
• performing correlation calculation between the digital calibration signal and each of the third digital signals to calculate transmission delay characteristics each corresponding to respective one of the antenna elements;
• calculating transmission delay correction amounts based on the transmission delay characteristics, each of the transmission delay correction amounts corresponding to respective one of the antenna elements;
• and
• correcting the transmission delay characteristics based on the transmission delay correction amounts.

A reception method performed by a receiver including a plurality of antenna elements, the reception method comprising:

• generating a digital calibration signal;
• performing transmission processing including digital-to-analog conversion on the digital calibration signal to generate a first analog signal;
• performing reception processing including analog-to-digital conversion on third analog signals to generate first digital signals each corresponding to respective one of the antenna elements, the third analog signals being obtained by adding the first analog signal to each of a plurality of second analog signals, the second analog signals each received via corresponding one of the antenna elements;
• performing correlation calculation between the digital calibration signal and each of the first digital signals to calculate reception delay characteristics each corresponding to respective one of the antenna elements;
• calculating reception delay correction amounts based on the reception delay characteristics, each of the reception delay correction amounts corresponding to respective one of the antenna elements;
• and
• correcting the reception delay characteristics based on the reception delay correction amounts.