Research On High Speed Railway Handover Algorithm Based On LTE

With the rapid development of high-speed railway construction and the continuous improvement of train operating speed,train control systems have become more stringent in terms of railway mobile communication technology.The increasing demand for wireless communication technology has become an indispensable factor to promote the sustainable development of high-speed railways.The communication system based on Long Term Evolution(LTE)has the advantages of high data rate,flexible system deployment,and low network delay.Unternational Union of Railways(UIC)has decided that the next-generation railway mobile communication system will move to Long Term Evolution for Railway(LTE-R).And the handover is an important part of the railway mobile communication system.Once the handover fails,communication between the train and the ground will be interrupted,which will cause serious safety risks to high-speed trains.Therefore,in-depth research on the handover scheme of the LTE-R system is of great significance for ensuring the reliability and safety of high-speed trains.Based on the analysis of key technologies of LTE-R system and handover related factors,a handover algorithm based on beamforming-distance and an early handover algorithm based on dual-cast mechanism and location assistance are designed.The former is mainly from the perspective of signal receiving power and handover timing.The latter is considered from the perspective of handover delay.In order to achieve the purpose of improving the performance of handover,and verify the effectiveness of the algorithm through theoretical analysis and software simulation.Firstly,introduce the overall architecture of the LTE-R system,then explain the core network and access network in the architecture,then analyze the key technical support of the LTE-R system,and describe in detail the railway wireless coverage method,handover process and handover classification provides theoretical basis and ideas for the design of subsequent handover algorithms.Secondly,the large-scale fading of the wireless channel is simulated and analyzed to provide a basis for the simulation verification of the handover algorithm.Aiming at the effect of train speed on the handover decision,a speed-based handover hysteresis dynamic adjustment method is presented.Then,a beamforming-distance-based handover algorithm is designed.The beamforming gain is adjusted in different ranges of the handover overlap area and a distance factor is added to achieve the purpose of avoiding communication interruption and assisting handover.The implementation method of beamforming-distance switching algorithm is explained in detail,and then a probability model and theoretical analysis of the proposed algorithm are established,and the validity of the algorithm is verified by Matlab tool simulation.Finally,design an early handover algorithm based on the dual-cast mechanism and location assistance,using the pre-bearing point as a reference point,to start the dual-cast initialization process and the target cell allocation and resource reservation in sequence in advance in advance.Method for shortening handover time to improve handover performance.The method of signalling process analysis was used to evaluate the feasibility of the algorithm,and the validity of the algorithm was verified by Matlab software.