In a mobile communication system, each base station is provided with an array antenna, a section for estimating the respective directions of one or more mobile stations with which the base station is in communication, based on estimated incoming directions of radio waves received from these mobile stations, and sections for operating on respective signals of the antenna elements constituting the array antenna such as to shape the radiation pattern of the antenna to form peaks of directivity which are oriented in the estimated directions of these mobile stations, and can include a capability for shaping these peaks in accordance with estimated positions of these mobile stations, thereby minimizing interference between transmissions from that base station and communication being executed between other adjacent stations of the system, and minimizing the number of different transmission frequencies required in the overall system.