The purpose of inner loop power control of the WCDMA system is to maintain a certain signal-to-interference ratio of transmission signal power when the signals reach the receiving end. However, in different multi-path environments, even if the mean signal-to-interference ratio is kept above a certain threshold, it is likely that the communication quality requirement (BER or FER or BLER) is not satisfied. So a kind of outer loop power control mechanism is required to adjust the threshold of inner loop power control dynamically in order to meet the communication quality requirement. Through the estimation of signal bit error rate (BER) or block error rate (BLER), the upper layer of RNC or UE adjusts the target signal-to-interference ratio (SIRtarget) in fast power control to accomplish the goal of power control. Since this kind of power control is accomplished through upper layer, it is called outer loop power control. When the quality of the received signals becomes bad (that is, bit error rate or block error rate increase), the upper layer will increase the target signal-to-interference ratio (SIRtarget) to improve the quality of received signals