Design & Development Of Simulation Test Platform For Low Evacuated Tube High-speed Maglev Vehicle-ground Communication System

Evacuated Tube Transport(ETT)is a form of transportation based on magnetic levitation rail technology and building a vacuum tube operating environment to achieve zero air resistance and frictionless operation of trains.At present,research on ETT test line projects has been carried out at home and abroad,such as the foreign Hyperloop project and the domestic high-speed flying train project.The train-to-ground wireless communication system,as an important part of the flying train operation control system,carries system services such as train operation control,operation status monitoring,and works with other train control subsystems to ensure the safe operation of trains.Establishing a semi-physical simulation platform that can accurately describe the ETT wireless communication environment and test and verify the communication technology scheme has important cutting-edge research and practical guidance significance.Aiming at the vehicle-ground wireless communication system project of the vacuum tube high-speed train,a hardware-in-the-loop simulation platform is designed and implemented based on the open source software defined radio platform,3D modeling and wireless channel simulation technology.The platform supports the flexible adjustment of different frequency bands,the access of commercial terminal equipment to the Internet,the simulation of multiple physical links,and the simulation of services such as train control.At the same time,it supports software upgrades for the research of nextgeneration wireless communication technologies such as 5G/NR.The work of this thesis is summarized as follows:(1)The technical scheme of the vehicle-to-ground wireless communication system is studied and a simulation model of the evacuated tube vehicle-to-ground wireless communication system is proposed.According to the technical proposal of the project,it is based on LTE(Long Term Evolution)technology,includes three subsystems corresponding to the functions of LTE’s core network,access network(base station)and terminal equipment respectively.At the same time,considering its wireless simulation and business requirements,the LTE communication platform based on open source software radio is combined with the air interface wireless channel modeling solution to realize the simulation of the vehicle-ground wireless communication system.(2)Based on the ray tracing method and 3D physical modeling technology,the air interface wireless channel simulation in the ETT environment is realized.This thesis uses the indoor/tunnel scene modeling function in the 3D modeling software Win Prop,and refers to the tube CAD design of the full-scale test line of the background project and specific building materials,and consults the electrical characteristics of the material,and finally builds a vacuum tube 3D model.At the same time,based on the ray tracing and the main path model,the channel fading and leaky cable radiation in the ETT environment are studied.(3)Based on the open source software defined radio platform OAI(Open Air Interface)and SRSLTE(Software Radio System LTE),the core network and wireless access network of the simulation platform are deployed.The platform implements a complete LTE communication system network element function on multiple generalpurpose computers.The core network function is undertaken by OAI EPC,and network element modules are deployed on one server in a containerized manner based on the Docker platform.The base station and terminal functions are undertaken by the OAI e NB and SRSUE respectively,and are deployed on different servers,using radio frequency hardware to realize the simulation of transmitting and receiving.(4)Based on the built-up vehicle-ground wireless communication simulation platform,this thesis tests it including terminal network access,multi-device connection,multi-base station support and other functional aspects,as well as transmission bandwidth,throughput,delay,doppler frequency offset and other performance aspects.It is verified that the simulation platform can meet vehicle-ground wireless communication business requirements and key technology simulation requirements,and achieves the original design goals.There are 71 figures,23 tables,and 87 references.