基于SideLink的LTE-V2X联合切换方案设计

在LTE-V2X系统中，针对车载用户切换过程中蜂窝链路及SideLink(SL)链路质量不高以及SL辅助切换过程中SL链路易中断的问题，该文提出一种基于SL的联合切换方案，主要包含:联合切换流程设计、联合切换信令流程设计以及联合切换判决算法设计。首先，在联合切换流程中利用SL技术实现联合切换，并对执行联合切换的SL链路质量进行筛选，以保证联合切换的可靠性；其次，对联合切换信令流程进行了完善，以优化SL辅助切换过程中SL链路易中断问题；最后，在联合切换判决算法中将车载用户的移动方向纳入切换判决条件，从而减少不必要的切换。仿真结果显示，该文所提方案能有效提升切换成功率，与此同时还能有效减少执行LTE切换的次数。

A SideLink-assisted Joint Handover Scheme for Long Term Evolution -Vehicle to Everything System

For LTE-V2X(Long Term Evolution-Vehicle to Everything) system, the cellular link and the SideLink (SL) are usually unstable in the handover process, and the situation is even deteriorating when the SL is employed to assist the normal handover process. To solve these problems, an SL-assisted joint handover scheme is proposed for vehicles in the network, which mainly includes: joint handover procedure design, signaling design, and the joint handover decision algorithm. Firstly, the SL is established for the vehicles that are about to request for handover. The SL is set up between the pair of vehicles with the best channel quality to ensure the link reliability. Secondly, in order to tackle the perplexing problem of SL being vulnerable in the fast changing radio environment, the joint handover signaling procedure is optimized with respect to two different realistic circumstances. Finally, the vehicle’s moving direction is further included in making the handover decision, thus reducing unnecessary handover operations. Simulation results illustrate that the SL-assisted joint handover scheme can effectively ameliorate the handover success rate and reduce significantly the number of LTE handovers.