多速率CDMA系统中多址干扰对系统容量的影响

第三代蜂窝移动通信系统能以不同的数据率和服务质量（Quality of Service，QoS）支持不同类型的通信业务。随着同时接入系统的用户数目的增加，多址干扰（MAI）也逐渐增加，不仅严重影响了CDMA通信系统的性能，也限制了系统容量的提高，且在异步传输方式下，多址干扰将更为严重。为此，首先在理论上分析了多址干扰对单速率CDMA系统容量的影响；然后，通过计算机仿真，讨论了异步多速率CDMA通信系统中多址干扰对系统容量的影响。

Impact of Multiple Access Interference on Capacity of a Multi-rate CDMA System

The third generation cellular mobile communication system is expected to support various kinds of communication services with different data rates and quality of service(QoS).The mutual interference among users due to random access of date traffic,i.e.multiple access interference(MAI) not only severely degrades the performance of CDMA systems,and limits the capacity as well,and furthermore MAI will be more serious in an asynchronous link.In this paper,the affect of MAI to the capacity of single-rate CDMA systems is firstly theoretically analyzed,and then through simulation the capacity decline caused by MAI in an asynchronous multi-rate DS-CDMA system is discussed.