A radio unit (2000) separates a signal from a specific terminal among signals from array antennas (#1-#4) based on a reception weight vector calculated by a reception weight vector calculator (20). A reception response vector calculator (22) derives a reception response vector of a propagation path for the signal from the specific terminal. A transmission response vector estimator (40) regards an estimation result of the reception response vector calculator (22) as a composite waveform of a function of a plurality of frequencies, determined in accordance with a Doppler frequency, and predicts a transmission response vector at a time point of transmission by obtaining coefficients of respective function. A transmission weight vector calculator (30) controls antenna directivity in transmission, based on a prediction result of the transmission response vector estimator (40).