分布式天线系统中的系统下行中断概率分析

System Downlink Outage Probability Analysis in Distributed Antenna Systems

本文针对分布式天线系统的系统下行中断概率问题展开研究.文章首先建立了包含路径损耗、阴影衰落和瑞利衰落的复合信道模型.接着,在接收端采用最大比合并的方式接收信号,并运用矩生成函数推导出输出信噪比的概率密度函数.然后,对分布式天线采用选择传输策略,并分析出给定移动台位置时的中断概率的表达式.最后,考虑小区内移动台任意分布特点,进一步推导出系统下行中断概率闭合表达式.仿真结果表明,所推导的闭合表达式能准确地评估系统中断概率性能.

The main focus of this paper is to investigate the system downlink outage probability in distributed antenna systems（DAS）.Firstly,this paper establishes a composite channel model which takes into account three factors such as path loss,lognormal shadowing and Rayleigh fading.Then,by making use of the moment generating function（MGF）,this paper derives the probability density function（PDF） of the output signal-to-noise ratio（SNR） after maximal ratio combining（MRC） at the receiver.After that,an approximate analytical expression of the outage probability for a mobile station（MS） over a given position is derived with an antenna selective transmission（ST） scheme.Further,considering the distribution of MSs in the system,a closed-form expression of the system outage probability is obtained.Numerical results show that the closed-form expression can provide sufficient precision for evaluating the outage probability performance of DAS.