Abstract: A Vehicular Ad-Hoc Network(VANET) is a Mobile Ad-Hoc Network(MANET) composed of mobile vehicular nodes.It does not rely on infrastructure to either establish a communication link orrealize communication. Owingto the high mobility of vehicles and limited wireless-communication resources, it is difficult for VANETs to guarantee Quality of Service(QoS).To solve this problem, this paper introduces a Software-Defined Network(SDN).In particular, amulti-constrained QoS routing algorithm suitable for Doftware-Defined Vehicular Ad-Hoc Network(SDN-VANET) is proposedthatharnessesthe advantages of SDN control and forwarding separation to ensurevehicle QoS.First, the SDN controller schedules a vehicle's service based on deadline constraints.Second, this paper proposesan Adaptive Hybrid Shuffled Frog-Leaping Algorithm(AH-SFLA).The SDN controller calculates the appropriate value of the data on the transmission link according to the QoS index and the global topology information and uses this as a benchmark to search for an optimized path.At the same time, alternative link mechanisms and QoS resource consumption thresholds are set to implement routing maintenance in order toreduce the probability of network failures.Finally, mininet-wifi and SUMO are combined to build an SDN-VANET environment, and the AH-SFLA routing algorithm is compared with the performances ofIGA and IICSFLA.The experimental results show that compared with IGA and IICSFL, AH-SFLA can improve the average end-to-end delay index by 57.74% and 46.6%, reduce the packet-loss rate by 29.9% and 18.6%, and increase the cost of standardized routing by 36.93% and 27.2%, respectively, effectively guaranteeingQoS in VANET.

Key words: Vehicular Ad-Hoc Network(VANET), Software-Defined Network(SDN), frog leaping algorithm, adaptive, Quality of Service(QoS)

摘要： 车载自组织网络（VANET）是由移动车辆节点组成的移动自组织网络（MANET），其不依赖基础设施即可建立通信链路实现通信。由于车辆的高机动性和无线通信资源的限制，VANET难以保障车辆业务的服务质量（QoS）。针对该问题，引入软件定义网络（SDN），提出一种适用于软件定义车载自组织网络（SDN-VANET）的多约束QoS路由算法。利用SDN控制转发分离的优势保障各业务的QoS，SDN控制器会根据车辆业务的截止日期对业务实现顺序调度，并基于蛙跳算法设计自适应中继节点选择算法（AH-SFLA），SDN控制器根据QoS指标和全局拓扑信息计算数据在传输链路上的适度值，以此为基准搜索优化路径。在此基础上设置备选链路机制和QoS资源消耗阈值共同实现路由维护，减少网络故障发生的概率。联合Mininet-wifi和SUMO搭建SDN-VANET环境，并将AH-SFLA路由算法与IGA、IICSFLA进行对比验证分析。实验结果表明，与IGA和IICSFL相比，AH-SFLA在平均端到端延迟指标上分别提高了57.74%和46.6%，丢包率平均降低了29.9%和18.6%，标准化路由开销提升了36.93%和27.2%，能有效保证VANET中的QoS。

关键词: 车载自组织网络, 软件定义网络, 蛙跳算法, 自适应, 服务质量

CLC Number: 

• TP393