ABSTRACT
ABSTRACT: LTE is one of 3GPP standards developed as a fourth-generation mobile communications standard. In order to solve signal strength problems when the mobile users as UEs are located on the edge of a LTE eNB signal converge area. A new entity called Relay Node (RN) was introduced in LTEAdvanced by 3GPP. Compared to eNB device, the RN has low-power consuming, low-cost features, and can be used to enlarge the eNB radio signal coverage. This manuscript focuses on RN operating in High Speed Rail (HSR) to serve high-speed rail passengers. Since the RN equipped in HSR carriage becomes moveable, we called this type of moveable RN as Mobile RN (MRN). When UEs get on the rail carriage, UEs should automatically re-setup their connections to HSR's MRN. However, the period of conventional handover procedure might not enough for leaving UEs, since there are only 2-3 minutes for a rail arrival and departure at HSR station. Also, a large number of handover procedures would be triggered by many leaving UEs at HSR station due to sudden disconnections after the rail departure. It would further instantly increase the loads of handover signal process on LTE core network. This manuscript proposes a vertical handover scheme based on prediction of the UE’s movement on a HSR train. Furthermore, the proposed scheme with two mechanisms can prepare vertical handover in a short period and reduce huge signals overhead. The simulation results have demonstrated that the proposed scheme with two mechanisms has better performance than the conventional handover scheme. The proposed scheme also can smooth the handover overhead and reduce system load.
