Cdma mobile communication system in which updating of a reference value for controlling closed-loop transmission power is realized in a base transceiver station

A method of controlling transmission power in a CDMA mobile communication system wherein an uplink signal target SIR value that serves as the reference in closed-loop transmission power control is updated in a base transceiver station;

• said method comprising the steps of:
• when a loss of synchronization of a user signal from a mobile station is detected, adding a predetermined step value ASIR to an uplink signal target SIR value that has been reported from a base station controller and making the result an uplink signal target SIR provisional value;
• and
• if this uplink signal target SIR provisional value is smaller than an uplink signal target SIR maximum value that has been set in advance, updating the uplink signal target SIR value that serves as the reference for closed-loop transmission power control to said uplink signal target SIR provisional value.

A CDMA communication system provided with at least one mobile station that communicates with a base transceiver station via radio signals, a base station controller for controlling base transceiver stations, and a base transceiver station for implementing closed-loop transmission power control using, as a reference, an uplink signal target SIR value that has been reported from said base station controller;

• wherein said base transceiver station comprising:
• a means for adding a step value ASIR that has been set in advance to the uplink signal target SIR value that has been reported from said base station controller and uses the result as an uplink signal target SIR provisional value, when a loss of synchronization of a user signal from said mobile station is detected;
• and
• a means for updating the uplink signal target SIR value that serves as a reference in closed-loop transmission power control to said uplink signal target SIR provisional value, when this uplink signal target SIR provisional value is smaller than an uplink signal target SIR maximum value that has been set in advance.