Handover Performance Improvement for Ultra Dense Network of High-Speed Railway

Nowadays the implementation of mobile Internet access services for high-speed railway (HSR) passengers are facing several challenges. In particular, the extra penetration loss of the train, frequent handovers, poor received signal and handover lag caused by fast time-varying fading channel may result in serious communication interruption. This paper investigates the mobility management of heterogeneous ultra dense network for HSR, in which macro base stations (BS) provide seamless coverage and millimeter-wave (mmWave) super micro BS provide high data rate services. With this network approach, a gray model (GM) prediction based handover algorithm is designed to prevent handover lag. To ensure service continuity for passengers, a combination factor is introduced into the handover decision to select target BS. Extensive simulation results prove the superiority of the proposed handover scheme in reducing handover failure probability and providing passengers with continuous services.