Wireless Channel Modeling And Coverage Optimization Design For GSM-R Network

GSM-R as the railway mobile communication network in use at present,can provide the carrying services required by train control system in various topography and railway areas such as tunnels,stations,mountainous areas,urban areas,plains and hills along the passenger and freight tracks,as well as satisfy the wireless communication needs of passengers on high-speed trains.However,with the continuous improvement of railway operation speed,the CTCS-3 train control system puts forward higher business requirements,Quality of Service(QoS)requirements and network design requirements for GSM-R network.In high-speed railway mobile communication,the receiver may be affected by doppler frequency shift and multipath fading,resulting in network switching failure or even communication interruption.This thesis focuses on the wireless coverage optimization design of GSM-R network of high-speed railway(referred to as high-speed railway).Firstly,the thesis analyzes the development of mobile communication network and its role in railway transportation.The subsequent study summarizes the characteristics of wireless channel fading including large-scale fading and small-scale fading,which lays a theoretical foundation for research.The review of various network channel modeling methods shows that the deterministic model and the statistical model are not suitable for modeling on high-speed mobile terminals such as railways.The former is often more suitable for the design of fixed-scenario signal networks,while the latter requires a large amount of The statistics may not cover all communication scenarios.The semi-deterministic model combines statistical records with simulation schemes and is a more common type of modeling.Summarizes the commonly used methods in network optimization and common problems such as signal coverage.Through the summary of the problems and optimization test of a high-speed rail line GSM-R network,the base station frequency planning of the public network or private network of the GSM-R network is not proper.The E-GSM frequency band(930~934MHz)used by the railway network has Obvious third-order intermodulation interference interferes with the GSM-R network.The use of band-stop filters(930~934MHz)for moving public/private network base stations along the railway can effectively reduce GSM intermodulation interference and avoid signal interference.Optimize the frequency configuration of the mobile public network or private network base station along the dedicated railway,and use the frequency point above 45 to avoid third-order intermodulation interference to the railway GSM-R network.At the same time,the analysis shows that in a high-speed railway transportation,a certain base station failure can cause a handover problem,and the adjacent base station is not correctly cut.At this time,by adjusting the handover threshold and increasing the handover difficulty,the handover problem of the base stationduring transportation can be reduced.At the same time,the common problems of GSM-R network in the speed train are sorted out.Signal weakening and multi-base station switching are common problems.