基于SIR平衡的功率控制可能存在正反馈的问题,从而使得系统不稳定。讨论了在加性高斯白噪声及Rayleigh衰落信道下,CDMA上行链路闭环功率控制系统的SIR上限问题。通过折衷考虑系统的容量与QoS要求,可以确定临界稳定时的目标SIR上限,在设计功率控制算法时,目标SIR只有满足上限要求,才能确保CDMA系统稳定。 The power control based on SIR balance may have the problem of positive feedback, which makes the system unstable. The SIR ceiling of CDMA uplink closed-loop power control system is discussed under additive white Gaussian noise and Rayleigh fading channels. By compromising the capacity and QoS requirements of the system, the upper limit of the target SIR for critical stability can be determined. When designing the power control algorithm, the target SIR can only ensure the stability of the CDMA system only when the upper limit is satisfied.