Wireless Channel Modeling And Simulation For High-Speed Railway Viaduct Scenario

The rapid development of railway has greatly improved the efficiency of railway transportation, so that the people of different city closely together.In order to ensure the safe operation of high-speed trains, the study of new high-speed railway communication systems is especially important. To build a high-speed railway wireless channel model is the basis of coding and modulation, channel estimation for high speed railway wireless communication system. The high-speed railway viaduct is the most common operating environment, so wireless channel of this environment is the focus of this study.This paper first introduces the basic theoretical knowledge of the wireless channel. According to the large scale fading and small scale fading, the paper analysis several classical path loss model and the small scale fading. And the paper discusses two kinds of distribution of small scale fading which are Rayleigh distribution and Ricean distribution. Because of the high-speed railway under a viaduct, classic wireless channel model has certain limitation. Therefore, the paper analyzes the path loss and small scale fading under a viaduct. In this environment, there is a line of sight path between the transmitter and receiver, so the envelope of received signal subject to the Ricean distribution. In this paper, channel modeling based on sight and non-line-path path. Line-of-sight path modeling is not consider propagation delay and loss, only consider the doppler frequency shift. NLOS path modeling is Rayleigh fading signal There are several simulation methods to generated Rayleigh fading signal, we studied three methods. Based on the location of the train from the sation, the viaduct is divided into several areas. According to the references given in the path of each location number, time delay, the average path gain, this paper established a wireless channel model.Finally, the channel model under a viaduct were simulated. According to the value of path loss analyzes the received signals at different positions and the inpact of train’s velocity on the received signal. The paper verify the probability density function and the cumulative distribution distribution function of the received signal, as well as Ricean K factor values.