Abstract: A transmit power control method in a Code Division Multiple Access (CDMA) mobile communication system includes checking whether more than one base transceiver station (BTS) is connected. When two or more BTSs are connected, CH receive SIRs (Signal to Interference Ratios) corresponding to the connected BTSs are selected for a calculation. A reference value Sref is changed according to the calculation. When only one BTS is connected, the reference value Sref is set to an upper limit. The changed reference value Sref is reported to all the connected BTSs. The reference value Sref is decided in response to the variation in selection/synthesis gain due to an increase or decrease of the number of connected BTSs.

Abstract: The transmit power of a CDMA downlink channel is controlled from a base station by receiving a command signal from a mobile station requesting it to decrease the transmit power of the downlink channel. In response, the base station decreases the transmit power if a hypothetically decremented value of the transmit power is higher than a nominal lower limit of its power control range, and further decreases the transmit power if the downlink channel still has a quality higher than a specified value at the mobile station even when the hypothetically decremented value is lower than the nominal lower limit. The base station sets the transmit power equal to the nominal lower limit if the hypothetically decremented value is lower than the nominal lower limit and the downlink channel still has a quality higher than the specified value at the mobile station.

Abstract: A method for controlling a reference SIR used for a closed loop control in a CDMA mobile communications system is disclosed. When an uplink channel has insufficient communication quality, the reference SIR is increased by a predetermined increase amount. When the uplink channel has sufficient communication quality, it is determined whether the base station is involved in the closed loop control. When the base station in involved in the closed loop control, the reference SIR in decreased by a predetermined first decrease amount. When the bane station is not involved in the closed loop control, the reference SIR is decreased by e predetermined second decrease amount which is greater than the predetermined first decrease amount.

Abstract: The transmit power of a CDMA downlink channel is controlled from a base station by receiving a command signal from a mobile station requesting it to decrease the transmit power of the downlink channel. In response, the base station decreases the transmit power if a hypothetically decremented value of the transmit power is higher than a nominal lower limit of its power control range, and further decreases the transmit power if the downlink channel still has a quality higher than a specified value at the mobile station even when the hypothetically decremented value is lower than the nominal lower limit. The base station sets the transmit power equal to the nominal lower limit if the hypothetically decremented value is lower than the nominal lower limit and the downlink channel still has a quality higher than the specified value at the mobile station.