On Radio Propagation Model Under Typical Scenarios Of High-speed Railways

ABSTRACT:Railway transportation is welcomed in many countries around the world because of its accuracy, huge transport volume, low power consumption and small environmental effects. Along with the rapid progress of railway industry and train speed, the wireless communication system dedicated for train has become more and more strict to the data transmit rate and network reliability. It is well known that wireless communication is easily affected by the environment, distance and local terrain. So the received signal levels going through wireless channels have very complex fadings, which make the reliability of received data less dependable than that of wired systems. As a result, radio propagation modeling has always been a key in solving wireless channel pathloss and receive power issues. These radio propagation models under typical scenarios of high-speed railways aim to model specific scenarios of high-speed trains, complex radio environments and various surrounding along the rails. On the basis of some general models, the establishment of railway radio propagation can be derived from proper modification and adjustment.This paper mainly focuses on the radio propagation modeling of three typical railway scenarios:the viaducts, the tunnels and the cuttings. From the basic electromagnetic theories it is possible to apply different statistic models, and thus derive accurate formulas of receive power and field strength. After that, some actual testing data from Zhengzhou-Xi'an high-speed express is taken in the following analysis, and this part of work can be referenced for further researches.The total thesis is organized as follows:Chapter 1 introduces the national and domestic development of high-speed railways and related current researches; Chapter 2 introduces usual radio propagation models and their applicable scenarios, those models include classical empirical models and statistic models; Chapter 3 analyzes three typical scenarios and their radio propagation models geometrically, then derives the accurate receive field strength and power intensity expressions. Chapter 4 processes the actual testing data from Zhengzhou-Xi'an high-speed railway, contracts the landform characteristics and fits data with presented models. Chapter 5 summaries the whole thesis and evaluates the derived models, and then gives the possible research directions and suggestions regarding the future study based on current researches and studies.