Research On Key Technologies Of 5G-R Heterogeneous Networking With WLAN

Needs are mounting on research for the next generation of railway mobile communication system based on 5G.Developing and deploying key technologies of the railway communication network will further empower the business application with the new architecture of information and communication technology(ICT),accelerating the innovation of the whole railway industry.Thus the evolution from GSM-R to 5G-R is not only a change of single mobile communication technology,but a comprehensive,multi-dimensional and whole-scenario evolution with various key technologies.Under this background,this thesis has shed light on some key issues of the integration of 5G-R and WLAN.It mainly contributes to the following aspects:Firstly,two architectures of heterogeneous network between 5G-R and WLAN are summarized,then the key requirements of heterogeneous networking are analyzed from these three aspects below: heterogeneous network security,multi-access network transmission performance and wireless coverage.Secondly,a secondary authentication framework for WLAN access in loosely coupled heterogeneous network is designed and verified in various ways,aiming to satisfy the basic requirements for railway communication network security.The rationality and security of the protocol are verified by both formal and informal analysis,as well as automated protocol analyzing tools.Finally,the calculation and communication efficiency of the protocol are compared with other works.Thirdly,an optimal WLAN splitting strategy based on queuing theory in loosely coupled heterogeneous network is proposed.Packet average latency is selected as the optimization index in evaluating the performance of heterogeneous railway networks.The end-to-end delay of heterogeneous multi-access network is analyzed as well.Based on the mathematical model built on queuing theory and Markov chain,the delay optimization effect of parallel transmission strategy is verified through simulation,and the optimal WLAN distribution ratio with the lowest delay is determined.Eventually,a wireless coverage optimization scheme based on ray tracing is proposed.Taking the High Speed Railway(HSR)carriage as an example,the problems and challenges faced by high-speed rail wireless network coverage are firstly analysed.Then the physical model and ray model of HSR carriage are built and simulated in use of ray tracing theory,which leads to the engineering suggestions of train wireless LAN coverage,including the optimal combination of AP deployment number,deployment position and transmission power setting.