车体横向振动对高铁光通信指向误差的影响

Influence of train body lateral vibration on pointing errorin high-speed railway optical communication

为研究在高速列车场景下车体横向振动对自由空间光(free space optical,FSO)通信指向误差的影响,首先利用TB/T 3352—2014《高速铁路无砟轨道不平顺谱》中的轨向、轨距不平顺功率谱推导出横向合成不平顺谱公式,用谱公式仿真生成横向合成不平顺数据;其次建立1/4车体3自由度横向车体振动模型,使用拉普拉斯变换推导出车体横向振动微分方程组的传递函数,搭建车体振动的Simulink仿真模型,推导车体横向位移的功率谱密度(power spectrum density,PSD),经统计得出仿真车体横向位移的概率密度函数(probability density function,PDF);最后利用车体横向位移PDF推导其导致的指向性误差的PDF。仿真验证了轨道横向合成不平顺谱公式、车体横向位移的PSD和PDF,以及横向位移导致的指向性误差的PDF。本研究获得的指向性误差的PDF可用于高铁FSO通信链路的信道建模和系统性能分析。

In order to study the influence of train body lateral vibration on the pointing error of the free space optical(FSO)communication in the case of high-speed railway,first and foremost,the formula of lateral composite irregularity spectrum was derived by employing the spectrum of track direction and gauge irregularity of TB/T 3352—2014 the PSD of ballastless track irregularities of high-speed railway,with the lateral composite irregularity data simulated by the spectrum formula;next,a 3-DOF lateral vibration model of 1/4 train body was established,and the transfer function of differential equations of lateral vibration of train body was derived by using the Laplace transform,constructing the Simulink model of the train body vibration.The power spectrum density(PSD)of the lateral displacement of the train body was derived,obtaining statistically the probability density function(PDF)of the simulated lateral displacement of the train body;finally,the PDF of pointing error caused therein was further derived by using the PDF of the lateral displacement of the train body.The simulation has verified the formula of track lateral composite irregularity spectrum,the PSD and PDF of the lateral displacement of the train body,and the PDF of pointing error caused by lateral displacement.The PDF of pointing error obtained in this study can be used for channel modelling and system performance analysis of high-speed railway FSO communication link.