Research On Handover Algorithm And Key Technology For High-Speed Railway Communication System

With the development of information society, the explosive growth of data services as well as wireless mobile Internet to flourish, high data transfer rates of long-term evolution of technology has been widely used around the world. The fourth generation TD-LTE communication system which dominated by China has also been formally put into commercial use in December2013. The popularity of wireless mobile Internet generates great requirements to enjoy high-speed wireless data transmission all the times. Due to its rapid and convenient and other characteristics, high-speed railway system in China has achieved tremendous development, which is on a large scale.How to integrate high-speed4G mobile system and high-speed railway system optimally has become an urgent problem.This paper focuses on the optimization strategies of handover technology used by TD-LTE wireless communication system under the high-speed mobile environment. This paper does research into the handover technology based on geographic location information that designed for high-speed rail network and then proposes two optimal handover reference point selection algorithm. We propose a handover algorithm of high-speed rail TD-LTE for high-speed rail system based on the primary backup relay.Firstly, this paper introduces the particularity of the communication system in the high-speed environment and the impact generated by the high-speed environment on the communication system. Secondly, it introduces the TD-LTE network system architecture designed for high-speed railway system, the module functions and signaling processes based on different interfaces. Besides this paper introduces system-level simulation platform LTE-SIM for LTE, which includes the main function module and the main application scenes.On that basis, add and improve the platform capabilities, handover signaling process module, handover decision module, primary backup relay switching mobility management module and viaduct simulation scenarios.Then this paper does research into the handover technology for high-speed railway private network based on geographic information, simulates and analyzes packet loss rate and throughput performance of different switching reference point and gets the effect of different switching reference points on handover performance. On that basis, we propose a standard on how to judge the merits of the switch reference point, and design two best reference point switch selection methods specifically for high-speed rail network based on geographic information, and obtain the statistical result of the best switch reference point under different scenarios at different speeds by using LTE-SIM simulation, and get a switching performance indicators about this best switch reference point, including link failure rate (RLF), packet loss rate (PLR) and other parameters.At last, we propose a primary backup relay handover algorithm for high-speed mobility railway environment. We elaborate on the process of the algorithm, give the signaling flow chart and the system framework diagram and analyze the performance of the algorithm. The algorithm utilizes the high speed mobile network and length of train, and designes a handover process that the primary backup handover relay carries user data. It can effectively reduce the handover interrupt latency, increase handover success rate and system throughput and improve overall system handover performance.