An adaptive handover trigger scheme for wireless communications on high speed rail

Handover triggered probability is the probability of handover triggered before the train arrives at a specific position. A low handover triggered probability at the cell edge will result in serious communication interruptions and call drops. This paper analyzes the impact of overlapped area and user measurement report period on the performance of handover triggered probability. Moreover, an adaptive handover trigger scheme is proposed to guarantee a high handover triggered probability by configuring overlapped area and measurement report period adaptively according to the train speed. Numerical and simulation results are provided. It is shown that analytical results are close to the simulations. Moreover, using the proposed scheme, the handover triggered probability at cell edge approaches to 99.8% while the number of base stations is reduced by 17.6% compared to GSM-R systems. Finally, for high speed trains whose velocity is below 540km/h, it is verified that signal strength measurement report period can be configured to 200ms, just the same as that of long term evolution (LTE) systems.