随机射线方法研究无线电波多径传播特性

Multipath Propagation Properties of Radio Waves with Stochastic Ray Methods

把无线电波的物理传播环境建模为随机网格信道,使用最大熵原理得到发生k次反射随机射线在二维传播空间的概率分布。使用随机桥过程产生基本随机变量,以自由布朗桥过程和自由Langevin桥过程为例研究其统计特性,发现基本随机变量服从Rayle igh分布或者χ分布随机变量之和的分布。由基本随机变量得到描述无线信道特征参量(包括多径分量的到达时延,幅度增益绝对值和相位等)的表达式。对一个障碍物完全随机分布的二维传播环境的信道特性使用随机射线方法进行仿真分析,得到无线信道的一些特征参量的统计规律,结果与经典的信道特性一致,验证了随机射线方法的有效性。

The propagation environment of radio waves is modeled as random lattice channels, and the maximum entropy principle is utilized to calculate the probability of stochastic rays undergoing k reflections. The stochastic bridge processes are used to produce the basic random variables. Their statistical properties are analyzed in both cases of free Brownian bridge processes and free Langevin bridge processes. Their distribution is that of the sum of Rayleigh orx-random variables. The expression of channel parameters is constructed based on the basic random variables, including the time delay, the amplitude gains and the phase of muhipath components. Finally, the simulation is carried out in 2-dimensional random environment based on stochastic ray methods. The statistical properties of several characteristic parameters are obtained. They are consistent to the classical results. It demonstrates the effectiveness of the stochastic ray methods.