Research On Handover Scheme Of Wireless Communication Network Under High-Speed Railway

Due to the rapid development of high-speed railway technology and the continuous update and iteration of mobile communication technology,the communication system in the highspeed railway scene is transitioning from the Global System for Mobile CommunicationsRailway(GSM-R)to a dedicated railway mobile communication system based on Long-Term Evolution for Railway(LTE-R).It is anticipated that both GSM-R and LTE-R communication networks will coexist for an extended period of time.Addressing the urgent issue of providing users with a good quality of service(Qo S)during high-speed rail handovers,this paper investigates two aspects: horizontal switching between homogeneous networks and vertical switching between heterogeneous networks.The main research objectives are:(1)Establishing a communication system model in the high-speed rail scenario,based on the characteristics of mobile communication in this environment.A homogeneous network handover algorithm is proposed,which utilizes double-threshold judgment and analyzes important indicators such as handover trigger probability and handoff call drop rate.This algorithm effectively overcomes interference caused by the fluctuation of Reference Signal Receiving Power(RSRP)due to fading,and considers the randomness of such fluctuations.It employs large and small thresholds for handover decisions,triggering handover only when the RSRP difference exceeds the smaller threshold for a duration greater than the system preset or immediately when it exceeds the larger threshold,thereby achieving a continuous and stable connection state.This algorithm also ensures that handover occurs when the high-speed rail crosses a base station(BS)coverage overlapping area,effectively avoiding untriggered handover due to various factors.(2)Addressing the characteristics of the heterogeneous network,a single RSRP is no longer suitable as the handover decision criterion.This paper models it as a multi-attribute decision-making problem and proposes a vertical handover scheme based on hierarchical adaptive weights.This scheme considers five attribute values of RSRP,delay,jitter,packet loss rate,and bandwidth,with RSRP being used as the necessary and sufficient condition for handover,and the rest of the attributes as optimizable conditions.The proposed approach constructs a decision matrix based on optimal conditions to obtain the subjective weight of each attribute value,and also calculates the objective weight of each attribute using the measured values of RSRP,delay,jitter,packet loss rate,and bandwidth.By combining the advantages of subjective and objective weights and considering the available range of each attribute value,the final weight of each attribute is obtained.Finally,a converged network consisting of LTER base station and GSM-R base station is designed,which can calculate the network contribution value of each network in different locations in real-time and select the appropriate network to connect into based on the sorted network contribution values.