Research On Handover Scheme For High-speed Rail Wireless Communication System

High-speed rail?HSR?has progressively developed over the few years.Since the high-speed train is greener,safer and with larger transport capacity,it is getting more popular.Meanwhile,with the appearance of abundant wireless devices,high demands for various wireless services are required for passengers during a long time travel.However,the existing broadband wireless technology is far from satisfying the great demands for Quality of Services?QoS?.There are high frequent occurrences of poor wireless services or even drop calls on high-speed rail.Many challenges occur for HSR,among which handover is a great one.The handover is a procedure for the user equipment to detach with a Base Station and set up communication with another Base Station for better communication quality.This paper introduces the research background and the developing process of cellular network at the beginning.Then several major characters of the handover on HSR are discussed,including higher handover frequency,group handover,Doppler shift,unstable signal quality and so on.An optimized seamless dual-link handover scheme is proposed.The trigger algorithm is able to obtain an optimal handover opportunity,which depends on Received Signal Strength of both antennas and provides front antennas more chances to reduce handover failure probability.By means of simulation,the handover failure probability falls to 10^-6 from 10^-4averagely.Moreover,communication interruption probability declines as the number of front-antenna handover increases.This paper aims at the 5G C/U plane spit heterogeneous network,which is a potential technology to provide HSR with higher capacity,better reliability.A seamless dual-link handover scheme with optimized threshold for C/U plane network is proposed.Both the theoretical analysis and the simulation demonstrate that the proposed scheme reduces the handover failure probability remarkably and avoids the unnecessary handovers.Moreover,when the front antenna has two chances to implement handover,the handover failure probability could drop by 0.15 averagely compared to the original single-antenna scheme.