车载自组网中基于车辆密度的多跳广播协议

Vehicle density based multihop broadcast protocol in VANET

在车载自组网中,介质访问控制协议(MAC)的转发效率直接影响了数据消息的多跳广播传输性能。现有方法通常在每跳覆盖范围内选择最远节点来承担转发任务,通过降低转发次数实现快速多跳广播覆盖。然而,通过仿真实验和模型分析,当车辆密度变大时,现有方法导致信道竞争的接入延时剧增。因此,提出了一种基于IEEE802.11p协议的多跳广播协议VDF,根据车辆密度自适应地选择转发节点。事故预警和在线游戏2种典型应用仿真实验结果表明VDF降低了全网广播消息的覆盖延时,同时取得了信道冲突程度和多跳覆盖速度的合理折中。

In vehicular ad hoc networks（VANET）, the medium access control（MAC） protocol was of crucial importance to provide time-critical multihop broadcast. Contemporary multihop broadcast protocols in VANET usually choose the farthest node in broadcast range as the forwarder to reduce the number of forwarding hops. However, it was demonstrated that the farthest forwarder may experience long contention delay in case of high vehicle density. An IEEE 802.11p-based multihop broadcast protocol vehicle density based forwarding（VDF） was proposed, which adaptively chose the forwarder according to the vehicle density. The evaluation results in safety warning and online game applications show that, VDF could shorten broadcast delay by achieving the proper trade-off between the contention delay and coverage speed.