Patent ID: 8010148

Claim:
A mobile terminal conducting a cyclic redundancy check on a transmitted signal from a base station to detect a communication environment of a communication with the base station, and increasing or decreasing a target SIR for deciding a transmission power from the base station, comprising a target Signal-to-Interference-Ratio (SIR) control unit that: after increasing the target SIR by a preset increase amount according to a No Good determination result of the cyclic redundancy check and before decreasing the target SIR by a burst error criterion that is a preset decrease amount, detects that the No Good determination result of the cyclic redundancy check occurs again, determines that a detected state is a burst error state indicating a deterioration in the communication environment, and decreases the target SIR by a first decrease amount whenever an OK determination result of the cyclic redundancy check is obtained after determining the burst error state; after detecting the burst error state, detects a state in which the target SIR is decreased by a burst error return criterion that is a preset decrease amount, determines that a detected state is a burst error return state indicating a return of the communication environment, and decreases the target SIR by a preset second decrease amount whenever the OK determination result of the cyclic redundancy check is obtained; and detects a state in which the target SIR is decreased by a normal communication criterion that is a preset decrease amount after detecting that the No Good determination result of the cyclic redundancy check occurs, or detects that the target SIR is below a preset normal communication state threshold value after determining the burst error return state, then determines that the detected state is a normal communication state indicating a good state of the communication environment, and decreases the target SIR by the first decrease amount.