Research On Interference Effects Of LTE Physical Layer Caused By The Electromagnetic Disturbance Of High-speed Railway

ABSTRACT:Because of its superior performance, TD-LTE technology has become the main technology of the next generation of railway communications. However, the electric locomotive environment is a typical large complex electronic environment, especially the threats to the entire railway communication system caused by the pantograph and catenaries’ offline noise. It is of great significance to the new generation of communications technology to research on a convenient and easy way which can solve the problem of noise impacts on LTE communication performance.So far, no one has given the exact mathematical expression relationship between statistics and reliability within a communication system, and a easy and simple operational solution has not been proposed. Even no one has given a solution that how to make it easier to obtain results using APD statistical measurement method since LTE system was applied to high-speed rail system.Based on the statistical parameters measuring method and the Gaussian noise, the paper obtains the amplitude probability distribution curve of Gaussian noise and LTE system bit error rate under Gaussian noise by building the LTE system model. We find that the trends of the two curves are very consistent. Therefore, according to the quantitative relationship between the two, the expression formula of noise amplitude limit-SNR (A-SNR) is obtained. In order to verify the correctness of the theory expression above, the paper analyzes the impact of Rayleigh noise on LTE system to get the further evidence of the feasibility of A-SNR formula in LTE systems.Secondly, the paper analyzes the main noise on high-speed rail, that is pantograph and catenaries’offline noise. Also, the paper compares the relationship formula mentioned in this article and the relationship formula between one-dimensional noise statistics APD curve and the LTE system bit error rate curve. The relationship formula of the paper is also suitable for the noise, thus we further verify the availability of it. In addition, using the proposed method, we can get the effect of pantograph and catenaries’ offline noise on the LTE uplink and downlink.Based on these conclusions, we only need the statistical noise amplitude probability distribution when studying the impact of noise on railroad communications in the high- speed rail LTE system. According to the bit error rate threshold of the railway system under normal operation, the corresponding SNR threshold is obtained, further we can get the noise amplitude threshold. Thus we can simply observing the amplitude of the noise to determine the effects of electromagnetic interference on high-speed LTE communications.The paper provides a reliable, easy and convenient method for the future research on the impact to LTE system reliability caused by various noises. Based on the conclusions of this paper we can further analyze the immunity performance of high-speed rail TD-LTE quantitatively.