Modeling And Research Of Wireless Channel In High-speed Railway Viaduct Scenario

Because of many merits of High-speed rail transport,in including strong cargo capacity,the external environment impact of small,low pollution to the environment,low power consumption and high safety coefficient,high-speed railway has become the inevitable railway development trend of future.Reliable and stable wireless communication system is the key to ensure the safe operation of high-speed trains,and the models of the wireless channel are the key of the communication system design.We can understand the performance of the system and provide the reference for the optimization and improvement of the existing communication system,through the establishment of the wireless channel model and simulation analysis.In the paper,it is studied that the channel model of wireless signal under different influence factors in viaduct scene.The main contents of the paper include:Firstly,this paper introduces the types of fading that may occur during the propagation of wireless signals.The propagation characteristics of the wireless channel and several classical channel models are analyzed from the aspects of large scale fading and small scale fading.The applicable scenarios and the conditions of different models are studied.The applicable conditions of the stochastic channel model based on geometric are discussed in combination with the characteristics of MIMO system channel,which provides a theoretical basis for establishing the channel model under the viaduct.Secondly,according to the characteristics of the high-speed railway viaduct,the influence of the height of the viaduct and the height of the transmitting antenna of the base station on the path loss in the process of wireless signal propagation is analyzed.So the channel statistical model based on the height of the viaduct H and the path loss model and path distribution based on the height h of the base station antenna is established.The simulation results are compared with the theoretical results,and the relevant influencing factors are modified to determine the best applicability of the channel model.Then,according to the characteristics of distance symmetry distribution between the receiving antenna and the transmitting antenna of the base station,the viaduct area is divided into five parts,and the regional model of the different positions under the elevated bridge scene is established.The wireless signal propagation and the path loss of different regions is analyzed,then the path distribution of different regions are determined.The multipath tap delay model based on distance is established.The path loss of different regions and the distribution characteristics of the Rice K factor are simulated and analyzed to determine the path distribution in different regions.After simulation analysis,the results of the probability density function and the cumulative distribution function of the received signal envelope in different regions are basically consistent with the results of the Rice K factor theory,so the actual channel in which the established channel model conforms to the wireless signal.Finally,the modeling process of the stochastic channel model based on geometry and the parameter generation method of the related model are analyzed.Based on the characteristics of the viaduct,the single-ring scattering model based on geometrical geometry is established,and the influence factors of spatial correlation of wireless signals are analyzed.After the model is established,it is simulated from the antenna number and tilt angle and so on.The simulation results are consistent with the measured results of the relevant references,which proves the correctness of the established high-speed railway wireless channel model and the influence of different influencing factors on system performance.