针对车载自组织网络VANET（Vehicular Ad Hoc Networks）中广播信息发送所面临的延迟大、不可靠的问题，提出一种基于车辆位置信息的快速、可靠的多跳广播算法LFRB（A Location-based Fast and Reliable Multi-hop Broadcast Algorithm）。提出的LFRB算法从车辆定期交换的Hello消息中获取邻居车辆的位置信息，建立邻居信息表，根据转发车辆所处位置选择距离该车辆最远（单一路段）或距离路口最近（路口）的若干车辆作为下一跳转发车辆的候选者，并采用指数退避机制选择一个候选车辆作为转发车辆来转发数据包。为了保证信息传输的可靠性，引入确认机制来提高成功转发的概率，同时还使用了缓存机制来避免数据包的重复转发，减少了网络冗余。NS2仿真结果表明，与现有的多跳广播算法相比，该算法具有较好的可靠性和较低的传输时延。%In light of the problems of long delay and unreliability the vehicular Ad hoc networks (VANET)encounters in its broadcast information transmission,in this paper we propose a vehicle location-based fast and reliable multi-hop broadcast algorithm (LFRB).LFRB obtains the location information of its neighbouring vehicles from Hello messages periodically exchanged among the vehicles and then establishes a neighbour information table.According to its location,the message forwarding vehicle selects several vehicles which are either the farthest from it (at single road)or the closest to the intersection (at an intersection)as the candidates for next hop forwarding.We also use exponent backoff mechanism to select a candidate vehicle as the forwarding vehicle to forward the data packet,and introduce the acknowledgment mechanism to improve the probability of successful forwarding in order to guarantee the reliability of information transmission. Meanwhile,we also use caching mechanism to avoid repeated packet forwarding and to reduce network redundancy.The NS2 simulation results show that the proposed algorithm has better reliability and low transmission delay compared with existing multi-hop broadcast algorithms.
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