Patent ID: 7366536

Claim:
A transmission power controlling method for a mobile packet communication system involving a mobile station, a plurality of base stations, and a radio network control apparatus that controls the base stations to achieve radio packet communication between the mobile station and one or a plurality of the base stations, the method comprising: a step in which the mobile station checks a signal state of a first downlink radio channel from each of one or a plurality of the base stations from which the mobile station can receive signal radio waves, and based on the signal state of the first downlink radio channel, transmits a transmission power control command to command a transmission power increase or decrease to each of the base stations through an uplink radio channel paired with the first downlink radio channel; a step in which each of the one or plurality of base stations specified by the radio network control apparatus to conduct communication with the mobile station checks a signal state of the uplink radio channel from the mobile station, and based on the signal state of the uplink radio channel, transmits a transmission power control command to command a transmission power increase or decrease through the first downlink radio channel paired with the uplink radio channel; a step in which the radio network control apparatus detects the number of diversity branches of the mobile station communicating with the base stations, increases an offset if the detected number of diversity branches is larger than a predetermined number, and decreases the offset if the number of diversity branches is smaller than the predetermined number, to thereby determine the offset; a step in which the radio network control apparatus specifies, from among the one or plurality of base stations, a transmitter base station to transmit signals to the mobile station through a second downlink radio channel and notifies the transmitter base station to set transmission power of the second downlink radio channel to transmit signals to the mobile station by multiplying transmission power of the first downlink radio channel by the offset; and a step in which the transmitter base station to transmit signals to the mobile station through the second downlink radio channel adjusts transmission power of the second downlink radio channel according to the notification from the radio network control apparatus and transmits downlink signals transferred from the radio network control apparatus.