Abstract: In order to achieve the low latency and high reliability transmission of the safety application messages in the Internet of vehicles (IoV), this paper designs a QoS-oriented time division multiple access (TDMA) protocol. The protocol uses TDMA technique, and considers the transmission requirements of two kinds of safety application messages, cooperative awareness message (CAM) and decentralized environmental notification message (DENM), respectively. The combination of traffic simulation software SUMO and network simulation software OMNeT++ is used to build a vehicular network simulation platform—Veins, in which the relationship of traffic simulation and network simulation is bidirectional coupling and they can interact in real-time. The simulation of QoS-oriented TDMA protocol is implemented on the platform, and the performance is verified on it too. The simulation results show that the designed protocol does not improve the transmission reliability of CAM obviously, but improves the transmission reliability of DENM, and reduces the message transmission delay of both DENM and CAM. Compared with the IEEE 802.11p protocol, in the high speed scenario and the urban scenario respectively, the reception probability of the CAM in the QoS-oriented TDMA protocol is reduced by 5.8% and 7.1%, and the transmission delay of the CAM in the QoS-oriented TDMA protocol is reduced by 11.4% and 12.8%, the reception probability of the DENM in the QoS-oriented TDMA protocol is improved by 10.5% and 12.9%, and the transmission delay of the DENM in the QoS-oriented TDMA protocol is reduced by 13.3% and 15.1%.

Key words: Internet of vehicles (IoV), multiple access, safety application message, time division multiple access (TDMA)

摘要： 为了实现车联网安全应用消息的低时延高可靠传输，设计了一种基于时分多址（time division multiple access，TDMA）面向安全应用消息服务质量（quality of service，QoS）的多址接入协议QoS-oriented TDMA。该协议采用TDMA技术实现，并同时考虑了协同感知信息（cooperative awareness message，CAM）和分布式环境通知消息（decentralized environmental notification message，DENM）两种安全应用消息的传输需求。采用交通仿真软件SUMO和网络仿真软件OMNeT++相结合的，交通与网络仿真双向耦合、实时交互的车联网仿真平台Veins，对QoS-oriented TDMA协议进行了仿真实现和性能验证。仿真结果表明，CAM传输可靠性虽然没有明显改善，但是QoS-oriented TDMA协议提高了DENM传输可靠性，并降低了CAM和DENM传输时延。与IEEE 802.11p协议相比，QoS-oriented TDMA协议高速场景和市区场景中CAM接收概率分别降低了5.8%和7.1%，传输时延分别降低了11.4%和12.8%；DENM的接收概率分别提高了10.5%和12.9%，传输时延分别降低了13.3%和15.1%。

关键词: 车联网（IoV）, 多址接入, 安全应用消息, 时分多址（TDMA）