中文摘要：

该文对基于非实时信道状态信息（Channel State Information,CSI）的多用户放大转发（Amplify-and-Forward,AF）协作通信系统的性能进行分析。系统采用一点对多点的通信系统模型,中继节点根据过时的CSI选择用户。通过推导得出中断概率、信道容量和符号错误概率（Symbol Error Rate,SER）的近似表达式。理论分析适用于链路同分布或者非同分布。仿真结果验证理论的正确性,并说明了各种参数对系统性能的影响。同时指出,增加用户数并不能提高系统性能,性能的提高可以通过改变中继的位置来实现。

英文摘要：

The performances analysis of a multiuser Amplify-and-Forward（AF） cooperative communication networks is presented based on the outdated Channel State Information（CSI）.The system architecture is point-to-multipoint and the user selection is based on outdated CSI.Asymptotical expressions of outage probability,channel capacity and Symbol Error Rate（SER） are derived.Analysis is applicable to Independent Identically Distributed（IID） or Independent None-identically Distributed（IND） fading channels.Finally,simulations are carried out to verify the correctness of theoretical analysis and illustrate the effort of parameters on the performance.Results show that performances dose not improve with the increase of user number and relocation of the relay node can be regarded as one way of performance enhancement.