Researching On The Characteristics Of Radio Propagation With High-Speed Railway Environment

Based on the research of the former, the basic characteristics of wideband radio wave with the multipath propagation environments of high-railway are researched. The distribution of the path-number, angle of incidence, times of reflection, attenuation and delay are analyzed, simulated and discussed by combining stochastic process theory with wireless communications principles. The emphasis is, with the analysis to the characteristics of instantaneous path-number distribution and the dynamic change characteristics of the path-number in the course of movement, the distributions that obey Poisson distribution and the Birth-and-Death process in finite state space respectively are presented, and deduced strictly; the suppose is presented that makes the mean of Poisson distribution equal to the mean of the Birth-and-Death process in finite state space and the parameter of Poisson distribution equal to the occurrence probability of the path of the Birth-and-Death process in finite state space, the dynamic simulation that the wave path-number received in the course of movement is realized, through a large amount of simulation testing to base band impulse response, the feasibility of this method is verified. The following conclusions are drawn:(1)Close to the mean of the Path-number, its distribution probability of the Birth-and-Death process in finite state space is between the Poisson distribution and the surveying value, which is larger than the former.(2) With the locomotive far from the base station, the phenomenon that mean time delay and square time delay reach unanimity will be observed.(3) In the vicinity or middle district, discrete time delay power spectrum is similar to index distribute. In the far district ,discrete time delay power spectrum is similar to mean distribute without visible wave.(4) If the relative power is certain, the influence of Doppler frequency on instantaneous relative power is depended on the union distribution of the azimuth and angle of elevation.(5) In every sample section, the instantaneous relative power spectrum keeps intacto If the length of sample section is smaller than the sampling distance, path-number will take place greater change, which may result greater influence on communication performance?,(6) With the increase of the speed of movement, path-number change time will be shorten .The azimuth in the direction and close to unanimous or opposite of the direction of the locomotive movement will act on longer time.