基于Markov过程的窄带地空信道建模与仿真

Modeling and Simulation of Narrowband Ground-to-Air Channel Based on Markov Process

针对大范围地空通信信道无法采用传统信道模型确切描述的问题,根据空基平台高度,利用Markov过程对改进和修正后的Rice信道模型和Loo信道模型进行相互转换来尽可能精确地描述地空衰落信道。对每个模型都将其分为经历轻度遮蔽和严重遮蔽2种状态,根据特定地区环境,利用Markov过程对2种不同环境状态进行切换。去掉多径来波入射角在[0,2π)上均匀分布的理想化假设,采用2个相关的实高斯随机过程构成Rice过程的方法,完成对Rice信道模型和Loo信道模型的改进和修正,推导得到了改进和修正后两模型的多普勒功率谱和幅相概率密度函数表达式。仿真结果表明:改进和修正后模型的多普勒功率谱曲线呈非对称形状,模型的自由度和适应性得到扩展和提升,可以描述不同信道情形对信号传输的不同影响,能较好地反映实际情况。

Aimed at the problem that the channel of wide-range Air-to-Ground communication is hard to be exactly described by adoting traditional model of channel, according to the height of flight platform, the Markov Process is utilized as exactly as possible to describe Air-to-Ground fading channel from the switch of the improved Rice model and Loo model. In the meantime, every model is divided into slight and heavy occlusion states, and the Markov Process is used to switch for the two different environment states according to special local environment. Getting rid of the ideal assumption that incident angles of arrival wave from multi-path are submitted to uniform distribution in , then two relevant and real Gaussian models are constructed as a Rice process, the Rice model and Loo model are modified and optimized, the Doppler power spectrum and Amplitude-phase Probability Density Function of the two models after modification are deduced. The simulation results show that the curve of Doppler power spectrum should be the unsymmetrical form after modification, hanced, the different influence to the degree of freedom （DOF） signal transmission in different and adaptability of the channel states is distinctly model are endepicted, and this can reflect the real conditions well.