The Influence Of Pantograph Arcing Radiation Disturbance On Communication Quality Of LTE-R

As a new generation of mobile communication technology,LTE(Long Term Evolution)has the advantages of high transmission rate,low delay,high reliability,and flexible configuration of carrier bandwidth.However,the pantograph arcing is one of the most important disturbance sources in the complex high-speed railways scenarios which leads many electromagnetic interference problems.The disturbance generated by pantograph arcing has a wide frequency range.The radiation fields can couple into the communication system on-board,and interfere sensitive equipment.In addition,the applicability of LTE-R in 400MHz frequency band should be considered according to the existing spectrum resource distribution in China.To address this problem,this thesis mainly studies the pantograph arcing disturbance coupled to the LTE-R antenna in a high-speed railway environment and analyzes the impact of this disturbance on the communication quality of the LTE-R system.The initial part of the thesis deals with the channel,transmission resources and key technologies of LTE-R physical layer downlink.The electromagnetic disturbance that may affect the quality of LTE-R communication is explained in terms of the system characteristics,operating principle,and operating frequency band of LTE-R.The results suggest that the main source of disturbance is pantograph arcing whose spectrum has a strong component in the LTE-R operating frequency band,which may damage the normal operation of the LTE-R system.Secondly,combined with the pantograph arcing signal collected by the railway actual test,the time interval between two pulses and the duration of a single pulse are explored for build a continuous pantograph arcing disturbance,which provides the basis for the analysis of the disturbance on LTE-R communication quality.Then,an equivalent calculation model is developed for pantograph arcing radiation field based on the generation mechanism of pantograph arcing and the theory of traveling wave antennas.The equivalent calculation model is used for analyzing the longitudinal propagation characteristics of pantograph arcing,and calculating the radiation field at the LTE-R antenna.At the same time,the coupling of the pantograph arcing radiation disturbance is simulated by electromagnetic simulation software to confirm the validity of the simulation results.The last part of this thesis focuses on modeling LTE-R downlink physical layer link in software.The pantograph arcing radiation voltage at the LTE-R antenna on board is added to the LTE-R to investigate the system performance changes,followed by an actual LTE-R throughput data measured from the test in the high-speed railway confirming the validity of the simulation.Theoretical analysis and simulation results have demonstrated that when LTE-R is interfered by continuous pantograph arcing disturbance,throughput decreases by 21%on average,and the BLER rises to 10^-1 with poor signal-to-noise ratio.That is,the pantograph arcing disturbance does not make the LTE-R system operating at 400MHz completely unavailable,but it will degrade the performance of LTE-R communication thus failing to meet the quality of service.