基于IEEE 802.11p的车载自组网MAC层接入算法RLBSA

RLBSA Algorithm for VANET MAC Layer Based on IEEE 802.11p

基于多业务的p-persistent模型提出实时侦听的自适应算法(RLBSA)。该算法针对VANET4种优先级设置提出利用计算信道冲突/空闲比来优化信道的利用率,即当信道空闲较多时,节点根据自适应策略增加发送概率;而信道冲突较多时,则降低发送概率。该算法解决了在多种优先级业务并存的条件下需要对各个优先级发送节点数量进行估计的问题,且可以根据网络负载自适应调整刷新发送概率的时长,克服了需要预先根据网络密度设置侦听周期长度的弊端。仿真结果表明该算法可以很好解决当网络中存在大量高优先级数据时AC3业务的冲突问题,同时低优先级数据也能保证其访问信道的机会。

A real-time listening based self-adaptive algorithm（RLBSA） is proposed in this paper to enhance the channel utilization rate according to the collision/idle ratio computed for four priorities of vehicular ad-hoc network（VANET）. The nodes increase the transmission probability when the channel is relatively idle and decrease when channel is relatively busy. RLBSA has no need to know the number of nodes which can hardly be acquired by using mathematical method. Moreover, RLBSA can regulate the adjustment period of transmission probability according to the network load other than the fixed period which needs to be previously set. The simulation shows that RLBSA can successfully handle the collision problem of high priority data and the starvation of low priority data in the scenario with high node density.