频率选择性衰落环境中MIMO系统信道容量研究  

On the capacity of MIMO systems in frequency selective fading environments

作　　者：王君[1] 朱世华[1] 王磊[1] 

机构地区：[1]西安交通大学电子与信息工程学院,陕西西安710049

出　　处：《电波科学学报》2006年第2期209-214,共6页Chinese Journal of Radio Science

基　　金：国家自然科学基金(60372055);国家高科技发展计划项目(2003AA123320);博士点基金(20020698024)资助

摘　　要：提出了一种频率选择性环境中多输入多输出系统信道容量的分析方法。该方法基于接收均匀圆阵构建了蕴含天线间距、散射角大小和多径数等模型物理参数的衰落空间相关模型。分析了MIMOOFDM系统信道衰落的统计特性。在此基础上利用Wishart分布的性质详细推导了任意天线数的MIMOOFDM系统的信道容量及其上下限。该方法回避了已有方法需要求取信道衰落相关特征值概率密度函数的问题,降低了运算量;并且可以有效地分析在频率选择性环境中模型物理参数对信道容量的影响。仿真结果表明,随着天线间距的增大,系统的平均信道容量也逐渐增大;但当天线间距增大到一定程度后,信道容量变化不明显。散射角越大,信道容量的增长速率越快。当接收信噪比较高时,平均信道容量的上下限接近于其实际值。A novel method was proposed to explore the channel capacity of Multiple Input Multiple Output （MIMO） systems in frequency selective fading environments. A fading correlation model considering antenna spacing,scattering angel and the amount of delay Spread was constructed assuming uniform circular antenna （UCA） at the receiver side. The stochastic characteristics of fading correlations were investigated. Then by using the properties of Wishart distribution, we derived the channel capacity and its upper and lower bounds for MIMO-OFDM systems with arbitrary number of antennas. The probability density function calculation of eigenvalues of the fading channel matrix was avoided and computational complexity was reduced in contrast to existing methods. With the proposed method, the impacts of channel model parameters on the channel capacity can be investigated effectively under frequency selective fading. Computer simulation results show that the channel capacity is maximized when the antenna spacing increases to a certain point, and further more, the larger is the scattering angle, the more quickly the channel capacity converges to its maximum. At high SNR, the upper and lower hounds on ergodic capacity are close to its real value.

关 键 词：多输入多输出 正交频分复用 衰落相关 信道容量 

分 类 号：TN929.533[电子电信—通信与信息系统]