车载自组织网络环境下基于软件定义网络的数据协作调度算法

针对车载自组织网络（VANET）中路侧单元（RSU）应答车辆请求效率低下的问题，提出基于软件定义网络（SDN）的数据调度算法SDDS。首先，依据车辆状态信息生成策略冲突图，并求解其最大权重独立集，实现单个周期内被应答请求数目最大化；其次，通过分析数据在车辆节点中的冗余度对系统服务能力的影响确定最优参数，设计了一种基于地理位置的协助车辆挑选机制；最后，分析跨区切换车辆的特点和影响多RSU协作的因素，提出一种基于冲突避免的多RSU协作机制；此外，提出了新的评价指标——服务效能来评价系统的整体服务质量。仿真实验中，相比请求数目优先算法（MRF）和协作数据分发算法（CDD），SDDS的服务效能最高增幅达到15%和20%。仿真结果表明，SDDS能显著提高调度系统的服务效率和质量。

Data scheduling algorithm based on software defined network for vehicular Ad Hoc network

Focusing on the issue that the Road Side Unit (RSU) has inefficient response to the request of the vehicles in Vehicular Ad Hoc Network (VANET), a data scheduling algorithm based on Software Defined Network (SDN) architecture, namely SDDS, was proposed. Firstly, a graph of conflicting policies was generated based on status information of vehicles, and a maximum weighted independent set of the graph was solved to maximize the number of satisfied requests in current cycle. Secondly, the redundancy of data in vehicles was analyzed to figure out the optimum parameter, and a selection mechanism for collaborative vehicles was designed based on geographical position. Finally, the characteristics of handover vehicles and some factors that would affect the multi-RSU cooperation were analyzed, and a multi-RSU cooperation mechanism was put forward based on collision avoidance. In addition, a new evaluation indicator, service efficiency, was proposed to estimate the overall quality of service. Simulation results showed that compared with Most Requests First (MRF) and Cooperative Data Dissemination (CDD) algorithms, the service efficiency of SDDS algorithm was increased up to 15% and 20% respectively. The simulation results prove that SDDS algorithm can observably improve the sevice eficiency and quality of scheduling system.