在闭环功率控制中,终端对下行链路的测量是对基站进行下行功控的基础,测量的准确性和及时性将对网络性能造成直接的影响。文中首先分析测量误差和时延产生的原因和量级,进而基于线性的功控模型,给出了测量误差和功控误差的计算方法,并得到链路BER解析式,最后分析了网络容量受影响的情况。仿真结果表明,测量误差标准差大于4 dB,时延对功控误差没有影响;大于10 dB,时延对链路性能和系统容量没有影响。要保证系统有较好的质量和容量,应将测量误差标准差控制在1 dB以内。因此,加强对入网终端测量能力的把控,对于提升网络整体性能将有积极的意义。
In closed loop power control for TD-SCDMA system, the control is based on the measurement of downlink from UE. In this paper the cause and magnitude of measurement errors and delay are analyzed, and a rigorous analysis on a simple analytical model based on stochastic linear system under imperfect conditions is presented, the simu- lation to show the relationship between measurement errors and demodulation threshold Eb/No is performed, and the im- pact on the capacity for TD-SCDMA system is extended. The results show that if the SIR measurement error standard de- viation is greater than 4dB, the measurement delay has no effect on power control errors; if the measurement error stan- dard deviation is greater than 10dB, then the link performance and system capacity has no difference. To ensure better system performance, the measurement error standard deviation should be less than ldB. Therefore, the enhancement of UE measurement ability testing will make the whole network better.