A wireless communication system in which at least a first base station and a second base station among a plurality of base stations (1-1, 1-2, 1-3) are operable to transmit data signals to a mobile terminal by collaborating with each other, the first base station including: a wireless receiving unit operable to receive from the mobile terminal a precoding-matrix-indicator notice value indicating a combination of a weight coefficient for the first base station and a weight coefficient for the second base station determined according to an estimated value of a propagation path condition between the first base station and the mobile terminal and an estimated value of a propagation path condition between the second base station and the mobile terminal; a transfer unit operable to transfer the precoding-matrix-indicator notice value received by the wireless receiving unit to the second base station; and a first precoding unit operable to perform precoding of a data signal to be transmitted by collaborative transmission to the mobile terminal performed by the first base station and the second base station according to predetermined timing, by using the weight coefficient for the first base station identified by means of the latest precoding-matrix-indicator notice value received by the wireless receiving unit, the second base station including: an information receiving unit operable to receive the precoding-matrix-indicator notice value transferred from the first base station; and a second precoding unit operable to perform precoding of a data signal to be transmitted by collaborative transmission together with the data signal transmitted from the first base station according to the predetermined timing, by using the weight coefficient for the second base station identified by means of the latest precoding-matrix-indicator notice value received by the information receiving unit and different from that for the weight coefficient for the first base station used for precoding of the data signal to be transmitted by collaborative transmission according to the predetermined timing. a wireless receiving unit operable to receive from the mobile terminal a precoding-matrix-indicator notice value indicating a combination of a weight coefficient for the first base station and a weight coefficient for the second base station determined according to an estimated value of a propagation path condition between the first base station and the mobile terminal and an estimated value of a propagation path condition between the second base station and the mobile terminal; a transfer unit operable to transfer the precoding-matrix-indicator notice value received by the wireless receiving unit to the second base station; and a first precoding unit operable to perform precoding of a data signal to be transmitted by collaborative transmission to the mobile terminal performed by the first base station and the second base station according to predetermined timing, by using the weight coefficient for the first base station identified by means of the latest precoding-matrix-indicator notice value received by the wireless receiving unit, an information receiving unit operable to receive the precoding-matrix-indicator notice value transferred from the first base station; and a second precoding unit operable to perform precoding of a data signal to be transmitted by collaborative transmission together with the data signal transmitted from the first base station according to the predetermined timing, by using the weight coefficient for the second base station identified by means of the latest precoding-matrix-indicator notice value received by the information receiving unit and different from that for the weight coefficient for the first base station used for precoding of the data signal to be transmitted by collaborative transmission according to the predetermined timing.