基于MEC服务器优先服务的路侧单元MAC层调度策略

MAC layer scheduling strategy of roadside units based on MEC server priority service

针对多接入边缘计算(MEC)服务器高可靠、低时延和大数据量的数据传输要求,基于无冲突接入、优先级架构和弹性服务技术,提出一种适用于车辆边缘计算场景下的媒体访问控制(MAC)调度策略。所提策略由车联网(IoV)路侧单元(RSU)集中协调信道接入权,优先确保车载网络中车载通信单元(OBU)与MEC服务器之间的链路传输质量,以及时传输车辆到网络(V2N)业务数据;同时,对本地OBU之间的业务采取弹性服务方式,增强密集车辆接入时应急消息传输的可靠性。首先,构建调度策略的排队分析模型;其次,根据各时刻系统状态变量的无后效性特点建立嵌入式马尔可夫链,并通过概率母函数的分析方法对系统进行理论分析,得到MEC服务器通信单元和OBU的平均排队队长、平均等待时延和RSU查询周期等关键指标的精确解析表达式。计算机仿真实验结果表明,统计分析结果与理论计算结果一致,所提调度策略在高负载情况下能够提高IoV的稳定性和灵活性。

Aiming at the Multi-access Edge Computing(MEC)server data transmission requirements of high reliability,low latency and large data volume,a Media Access Control(MAC)scheduling strategy based on conflict-free access,priority architecture and elastic service technology for the vehicle edge computing scenario was proposed.The proposed strategy was based on the centralized coordination of channel access rights by the Road Side Unit(RSU)of the Internet of Vehicles(IoV),which prioritized the link transmission quality between the On Board Unit(OBU)and the MEC server in the vehicle network,so that the Vehicle-to-Network(V2N)service data could be transmitted in a timely manner.At the same time,an elastic service approach was adopted for services between local OBUs to enhance the reliability of emergency message transmission when dense vehicles were accessed.First,a queuing analysis model was constructed for the scheduling strategy.Then,the embedded Markov chains were established according to the non-aftereffect characteristics of the system state variables at each moment,and the system was analyzed theoretically by the analysis method of probability generating functions to obtain the exact analytical expressions of key indicators such as the average queue length,and the average waiting latency of MEC server communication units and OBUs,and RSU query period.Computer simulation experimental results show that the statistical analysis results are consistent with the theoretical calculation results,and the proposed scheduling strategy can improve the stability and flexibility of the IoV under high load conditions.