车路协同网络中服务功能链可行时长优化映射算法

以车路协同网络为研究对象，针对物理链路间连通时长的差异性，本文提出优化可行时长的服务功能链映射算法。首先，建立车路协同的物理传输网络模型，并分别分析车车链路和车路链路的连通时长；其次，以映射可行时长为优化目标，以服务功能链的映射规则为约束，建立整数规划问题；最后，为求解该NP-hard问题，提出基于改进子图同构的映射算法，联合考虑车路协同环境中的节点属性、链路属性及链路间关联关系，设计剪枝策略，从而实现服务链路在物理链路上的组合优化映射。实验结果表明，通过考虑物理链路连通时长的差异性，并对其进行优化选择，提出算法在车间通信距离150m和最大车速60km·h-1 条件下，可将可行时长提升34.4%；同时，在车车通信范围、车辆数以及最大车辆速度这3项主要参数设置中均可验证发现，所提算法可有效提升映射可行时长。

Optimization Mapping Method on Feasible Duration of Service Function Chain in Vehicle-road Cooperative Network

Considering the difference in the connected duration of physical links in vehicle-road cooperative network, this paper proposes an optimization model of service function chains (SFC) mapping to maximize the feasible mapping duration. First, the physical transmission network model is proposed to represent the vehicle-road cooperative network, and the connected durations are analyzed for the vehicle-to-vehicle link and the vehicle-to-road link. Then, an integer programming problem is established, aiming to maximize feasible mapping duration with the mapping constraints of SFC. To solve the NP-hard problem, this paper provides an approximation technique based on the enhanced subgraph isomorphic and design the pruning based on node characteristics, link attributes, and the connection between links to reduce the complexity. By considering the difference in the connected duration of physical links and optimizing the selection, experimental results show that the feasible mapping duration of the proposed algorithm has increased by 34.4% under the communication range equal to 150 meters and the maximum speed of the vehicle equals 60 km ? h- 1 . Experimental results on the three main influencing factors, including the vehicle-vehicle communication range, the number of vehicles and the maximum vehicle speed, show that the proposed algorithm can effectively improve the feasible mapping duration of service.