车载自组织网络中面向安全应用的消息分发机制的研究

发布时间：2018-02-02 12:26

本文关键词： 车载自组织网络周期性安全消息紧急告警消息模糊逻辑交通流理论自适应单跳广播协议动态多跳广播协议　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：交通运输行业快速发展的同时也带来了诸如交通事故、拥堵及大气污染等问题。车载自组织网络中基于车间通信(V2V)的广播方式能够将安全消息在全网快速分发,使驾驶员的感知视野得到大范围拓展,保障交通运输的可靠性。车载自组织网络中的安全消息包括周期性安全消息和紧急告警消息两大类。周期性安全消息通过单跳广播方式周期性地传播,且只在一跳范围内的节点之间进行。现有的固定周期单跳广播协议在车流密度过大时易造成较大网络负载;而大多数自适应调整广播周期的单跳广播协议也存在影响因素分析不全面、模型复杂等局限性。因此,本文提出了一种基于模糊逻辑的自适应单跳广播协议FL-ASB(Fuzzy Logic Based Adaptive Single-hop Broadcast Protocol)。该协议综合考虑了车辆速度、一跳邻居节点数目、接收信号强度、能见度四方面因素,建立了基于模糊逻辑的广播周期自适应调整模型,动态调整周期性安全消息的广播周期,在实时性和信道负载之间找到平衡。紧急告警消息在VANET中具有更高的优先级,需要在更短时间内以更高的投递率传播给更远的车辆,因此通常以多跳广播方式传播。下一跳转发节点的选择机制和免碰撞机制是影响多跳广播协议实时性和可靠性的关键因素。现有的一些多跳广播协议通常不能根据交通流的变化动态调整通信区域的划分和竞争窗口的长度,时延过长,可扩展性差。为了应对上述问题,本文提出了一种基于交通流理论的动态多跳广播协议 TF-DMB(Traffic Flow Theory Based Dynamic Multi-hop Broadcast Protocol)。该协议基于交通流理论,模拟出不同车流密度下的车辆分布规律,从而实现如下两方面的动态特性:一是动态划分通信区域,一次定位候选转发节点,降低时延;二是根据车流密度的变化对竞争窗口大小进行动态的调整,使碰撞概率减小。本文通过VanetMobisim和NS2软件的联合仿真对协议进行性能验证。首先通过VanetMobisim模拟了设计时速120km/h的双向四车道高速公路,随后将轨迹文件导入NS2中,并分别对FL-ASB和TF-DMB两个协议进行时延、网络负载等方面的性能验证。仿真结果证明,与同类协议对比,FL-ASB和TF-DMB均具有良好的性能。
[Abstract]:The rapid development of the transportation industry has also brought about traffic accidents. Traffic congestion and air pollution. The broadcast mode based on workshop communication V2V) in the vehicle-borne ad hoc network can quickly distribute the security message across the whole network, so that the driver's perceptual field of vision can be expanded in a wide range. Security messages in vehicle-borne ad hoc networks include periodic security messages and emergency alarm messages. Periodic security messages are transmitted periodically through a single hop broadcast mode. The existing fixed cycle single hop broadcasting protocol is easy to cause a large network load when the traffic density is too high. However, most of the single-hop broadcast protocols with adaptive broadcast cycle adjustment also have some limitations, such as incomplete analysis of influencing factors and complex models. In this paper, an adaptive single-hop broadcasting protocol based on fuzzy logic, FL-ASB (. Fuzzy Logic Based Adaptive Single-hop Broadcast protocol. The protocol takes vehicle speed into account. One hop neighbor node number, received signal intensity and visibility are four factors. A fuzzy logic adaptive broadcast cycle adjustment model is established to dynamically adjust the broadcast period of periodic security messages. Find a balance between real-time and channel load. Emergency alarm messages have a higher priority in VANET and need to be transmitted to more distant vehicles in a shorter time with a higher delivery rate. The selection mechanism and collision free mechanism of the next hop forwarding node are the key factors that affect the real-time and reliability of the multi-hop broadcast protocol. Some existing multi-hop broadcast protocols usually cannot root. According to the change of traffic flow, dynamically adjust the length of communication area and competition window. Long delay, poor scalability. In order to deal with the above problems. This paper presents a dynamic multi-hop broadcasting protocol TF-DMBbased on traffic flow theory. (Traffic Flow Theory Based Dynamic Multi-hop Broadcast Protocol). The protocol is based on traffic flow theory. The vehicle distribution law under different traffic density is simulated, and the following two dynamic characteristics are realized: one is to divide the communication area dynamically, the other is to locate the candidate forwarding node once to reduce the delay; The second is the dynamic adjustment of the size of the competition window according to the change of the traffic density. In this paper, the performance of the protocol is verified by the joint simulation of VanetMobisim and NS2 software. Firstly, the design speed of 12 speed is simulated by VanetMobisim. 0km / h, two-way four-lane highway. Then the track file is imported into NS2, and the performance of FL-ASB and TF-DMB are verified in terms of delay, network load and so on. The simulation results show that it is compared with the similar protocols. Both FL-ASB and TF-DMB have good performance.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5;U495

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