基于概率及退避等待的车辆安全消息广播机制

Vehicular Safety Message Broadcast Mechanism Based on Probability and Backoff

在车辆自组织网中,针对安全消息广播的有效覆盖及竞争冲突问题,本文提出了基于概率及退避等待的广播机制(VANET Broadcast Mechanism based on Probability and Backoff,VBM-PB).该机制隶属于接受者机制,其复杂度低并且具有完全分布式计算特性.VBM-PB将车辆的地理位置信息和节点负载结合,计算各节点潜在的转发概率;构造概率转发函数并设计自适应退避等待方案,减少网络中数据包冗余、降低节点间数据发送冲突并保障消息覆盖率;利用超时重传机制确保消息发送的可靠性.仿真表明,VBM-PB与经典的几种广播机制相比,在数据包渗透速度、转发节点所占比例以及消息传输时延上均具有更好的性能.

In vehicular ad hoc network（VANET）, the efficient coverage and low transmission collision of safety message is the challenge. To solve this problem, a VANET broadcast mechanism based on probability and backoff（VBM-PB） are proposed in this paper. The mechanism is part of the recipient mechanism and is practicable due to low complexity and fully distributed computation. The geographical position and data load of vehicles are both considered to calculate the forward probability of each potential relay in VBM-PB. A function of forward probability is constructed combined with an adaptive backoff mechanism, which can reduce packet redundant in the network, relieve data collision among nodes and enhance coverage rate of safety message. Besides, timeout-retransmit mechanism is also applied to guarantee high reliability of transmission. The simulation results show that the performance of VBM-PB is superior to several traditional mechanism in terms of package permeability, forwarding node proportion and transmission delay.