高速铁路高架桥场景下无线通信信道建模与研究

发布时间：2019-01-10 09:35

【摘要】：高速铁路运输以其运行速度快、载货能力强、受外界环境影响小、对环境污染小、能耗低、安全系数高等诸多优点成为铁路发展的必然趋势。可靠稳定的无线通信系统是保证高速列车安全可靠运行的关键,无线信道的模型是通信系统设计的关键,通过建立无线信道模型并进行仿真分析可以了解无线通信系统的性能并对已有通信系统进行优化改进提供参考依据。论文研究了高架桥场景下无线信号在不同影响因素下的信道模型。主要内容包括:首先,介绍了无线信号传播过程中可能产生的衰落类型,从大尺度衰落和小尺度衰落两方面分析了无线信道的传播特性和几个经典信道模型,研究了不同模型的适用场景及适用条件,并结合MIMO系统信道特点讨论了基于几何的随机信道模型的适用条件,为建立高架桥场景下的信道模型提供了理论依据。其次,结合高速铁路高架桥的特点,分析了高架桥高度和基站发射天线高度对无线信号传播过程中路径损耗的影响,因此建立了基于高架桥高度H和基于基站天线高度h的路径损耗模型及路径分布情况的信道统计模型,并对建立的模型进行仿真,将仿真结果与理论结果对比,修正相关影响因子,使建立的信道模型适用性最佳。然后,根据经过基站前后列车的接收天线和基站发射天线之间距离对称分布的特点,将高架桥区域分为5个部分,建立了高架桥场景下不同位置的区域模型。通过分析不同位置下无线信号传播的路径分布情况,建立基于距离的多径抽头延迟模型,并对不同区域的路径损耗及莱斯K因子分布特性进行仿真分析,确定不同区域的路径分布情况。经过仿真分析,不同区域接收信号包络的概率密度函数和累积分布函数的仿真结果与莱斯K因子理论结果仿真对比基本一致,确定所建立信道模型符合无线信号的实际传播场景。最后,分析了基于几何的随机信道模型的建模过程及相关模型的参数生成方法。结合高架桥场景特点建立高架桥场景下基于几何的单环散射模型,并分析了无线信号空间相关性影响因素。从基站天线的数目,移动台天线的数目,天线的倾斜角等方面进行仿真验证。仿真结果与相关参考文献的实测结果基本一致,证明了建立模型的正确性及不同影响因子对系统性能的影响。
[Abstract]:High speed railway transportation has become the inevitable trend of railway development because of its advantages such as fast running speed, strong loading capacity, little influence by external environment, low environmental pollution, low energy consumption, high safety factor, and so on. The reliable and stable wireless communication system is the key to ensure the safe and reliable operation of high-speed train. The model of wireless channel is the key to the design of communication system. The performance of the wireless communication system can be understood by establishing the wireless channel model and simulation analysis, and the reference for the optimization and improvement of the existing communication system can be provided. In this paper, the channel model of wireless signal in viaduct scene under different influence factors is studied. The main contents are as follows: firstly, the possible types of fading in the process of wireless signal propagation are introduced, and the propagation characteristics of wireless channel and several classical channel models are analyzed from two aspects: large scale fading and small scale fading. The suitable scenarios and applicable conditions of different models are studied, and the suitable conditions of geometric stochastic channel models are discussed according to the channel characteristics of MIMO system, which provides a theoretical basis for the establishment of channel models in viaduct scenarios. Secondly, considering the characteristics of high speed railway viaduct, the influence of viaduct height and base station antenna height on the path loss in the process of wireless signal transmission is analyzed. Therefore, the path loss model based on viaduct height H and base station antenna height h and the channel statistical model of path distribution are established, and the simulation results are compared with the theoretical results. The correlation influence factors are corrected to optimize the applicability of the established channel model. Then, according to the characteristic of distance symmetry distribution between the receiving antenna of train and transmitting antenna of base station before and after passing through the base station, the viaduct area is divided into five parts, and the region model of different position in viaduct scene is established. By analyzing the path distribution of wireless signal propagation in different locations, the multipath tap delay model based on distance is established, and the path loss and the distribution characteristics of Rice K factor in different regions are simulated and analyzed. Determine the path distribution of different regions. Through the simulation analysis, the simulation results of probability density function and cumulative distribution function of the envelope of received signals in different regions are basically consistent with the simulation results of Les K factor theory. It is determined that the established channel model accords with the actual propagation scene of the wireless signal. Finally, the modeling process of the geometric stochastic channel model and the method of parameter generation of the related model are analyzed. Based on the characteristics of viaduct scene, a geometric single loop scattering model is established, and the influence factors of wireless signal spatial correlation are analyzed. The number of base station antennas, the number of mobile station antennas and the tilt angle of the antennas are simulated and verified. The simulation results are in good agreement with the measured results of relevant references, which proves the correctness of the model and the influence of different influence factors on the system performance.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN92;U285.2

【参考文献】