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

Abstract

A CDMA mobile communication system is disclosed in which a reference value, an uplink signal SIR value, which is used in a closed-loop transmission power control is updated in base transceiver stations. The uplink signal target SIR value is updated independently at base transceiver stations and not at the base station controller. At the base transceiver station, when a decoder detects a loss of synchronization of a user signal from a mobile station, a demodulator adds a step value ASIR that has been set in advance to the uplink signal target SIR value that has been reported from the base station controller to obtain an 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, the uplink signal target SIR value is updated to the uplink signal target SIR provisional value.

1 . A method of controlling transmission power in a CDMA mobile communication system, said method comprising the steps of: 
 updating, in a base station, an uplink signal target SIR value that serves as a reference in closed-loop transmission power control; and    executing, in said base station, said closed-loop transmission power control using said updated uplink signal target SIR value.    
   
   
       2 . 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.    
   
   
       3 . A base transceiver station for implementing closed-loop transmission power control using an uplink signal target SIR value that is reported from a base station controller as reference, said base transceiver station comprising: 
 a synchronization loss detection means for detecting loss of synchronization of a user signal from a mobile station; and    an updating means for adding a step value ΔSIR that has been set in advance to the uplink signal target SIR value that has been reported from said base station controller to obtain an uplink signal target SIR provisional value when said synchronization loss detection means detects loss of synchronization, and when said 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 in closed-loop transmission power control to said uplink signal target SIR provisional value.    
   
   
       4 . 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.