三维空间域多普勒功率谱及其多天线系统性能

Doppler power spectrum density and multi-antenna system performance in three-dimensional environment

在三维(3 dimensional,3D)空间域信道建模中,针对波达信号仰角(elevation angle,EA)在不同覆盖区散射体环境中的分布,提出了指数型EA仰角概率密度函数并对其信道特征实现建模.在假设波达信号方位谱为均匀分布时,采用近似算法在对称和非对称两种情况下导出其多普勒功率谱密度(power spectral density,PSD)闭合表达式.从分析结果可发现PSD与仰角函数式及波达信号边界角度参数βmin和βmax关系密切,并与多普勒频移密切相关.对该三维空间域中的多输入多输出(multiple input multiple output,MIMO)多天线信号衰落相关性(spatial fading correlation,SFC)进行了推导和仿真.结果表明MIMO多天线阵元间SFC与βmin和βmax关系密切,而EA仰角概率密度函数参数n对SFC影响较小.本文引入的指数型EA仰角概率密度函数可应用于多种无线通信环境下的信道参数估计,且与传统模型对比表明本模型的信道参数估计结果符合理论和经验值,拓展了对3D空间域统计信道的建模与MIMO多天线分析计算.

In this paper, we develop a series of exponential probability density functions for modeling different distributions of elevation angle （EA） of arrival signals in different tree-dimensional （3D） coverage area scattering environments, and implement the modeling of channel characteristics. First, by assuming that the distribution of azimuth angle is uniform, in this paper the closed-form expressions of power spectrum density （PSD） for both symmetric and asymmetric situations of EA are derived. It can be observed from the analysis results that the PSD is closely correlated to EA function and the boundary angles βmin and βmax of the arrival signals and also to the Doppler shift. Then the spatial fading correlation （SFC） of MIMO multi-antenna signals in 3D environment is derived and simulated. The results show that the SFC between MIMO multi-antenna elements is closely related toβmin andβmax, and the parameter of EA function has little effect on SFC. The exponential EA probability function which is introduced in this paper can be applied to channel parameter estimation of multiple wireless communication environments. Compared with traditional models, this model presents the parameter estimation that satisfies theoretical and empirical values, and this model also expands the modeling of statistical channel in 3D environment.