车路通信中MAC层消息传输机制研究

发布时间：2018-08-22 16:14

【摘要】：当前交通系统运行效率较低与人们出行要求越来越高的的矛盾已逐渐暴露出来,成为当前交通行业亟需解决的一个根本问题。因此,研究以车路通信为重要组成部分的智能交通系统也显得愈加急迫和重要。相比传统的无线自组织网络,其车辆节点的移动速度更快,对实时性、可靠性要求较高,从而导致网络拓扑变化更为频繁、链路中断现象增加,节点通信困难,这就使得车路通信研究面临巨大的挑战。本文对车路通信中的消息传输机制做了如下工作:1、对车路通信技术的研究背景和意义、国内外研究、车路通信网络的特点、DSRC技术的优势、WAVE/1609协议标准、DCF机制、CSMA/CA机制以及一些待解决的问题等方面进行了分析和归纳。2、提出了一种MAC层的动态优先级调度机制。先就车路通信网络中的车辆运动模型、安全消息的相关研究等方面进行了归纳总结,然后分析并指出了现有的车路通信中存在的一些问题,如车路通信中节点的通信模式会导致网络中存在大量的冗余安全控制消息,导致有意义的安全消息无法得到可靠和及时的传输。在分析消息传输的特点之后,建立包含时间、距离、方向的函数动态判定消息的优先级,根据方向过滤无意义的消息,并引入绝对优先级保证特殊车辆的顺畅通信。3、针对信道竞争问题,提出了一种自适应的退避算法。在分析信道竞争中存在不公平现象进行分析的基础上,结合了车路网络中节点移动特征。该算法综合考虑了节点的移动速度、方向、位置等参数,调整竞争窗口的值,分配相应信道访问的优先权。4、通过NS2的仿真平台和VanetMobiSim生成的节点运动模型,对提出的两种机制进行了吞吐量、时延、链路稳定性以及公平性等方面的评估,验证了所提出的两种机制的有效性。
[Abstract]:At present, the contradiction between the low efficiency of the transportation system and the higher and higher travel requirements has been gradually exposed, which has become a fundamental problem that needs to be solved in the current transportation industry. Therefore, it is more and more urgent and important to study the intelligent transportation system which is an important part of vehicle-road communication. Compared with the traditional wireless ad hoc networks, the vehicle nodes move faster, require higher real-time and reliability requirements, resulting in more frequent network topology changes, increased link disruption phenomenon, node communication difficulties. This makes the study of vehicular communication facing a huge challenge. This paper has done the following work on the message transmission mechanism of vehicle-road communication: 1, the research background and significance of vehicle-road communication technology, domestic and foreign research, The characteristics of vehicle-road communication network and the advantages of DSRC technology are analyzed and summarized in the aspects of WAV / 1609 protocol standard / DCF mechanism, CSMA / CA mechanism and some problems to be solved, and a dynamic priority scheduling mechanism in MAC layer is proposed. In this paper, the vehicle motion model in vehicle-road communication network and the related research of security message are summarized, and then some problems existing in vehicle-road communication are analyzed and pointed out. For example, the communication mode of nodes in vehicle-road communication will lead to the existence of a large number of redundant security control messages in the network, resulting in meaningful security messages can not be reliable and timely transmission. After analyzing the characteristics of message transmission, a function including time, distance and direction is established to dynamically determine the priority of the message and filter the meaningless message according to the direction. An adaptive Backoff algorithm is proposed to solve the channel competition problem by introducing absolute priority to guarantee the smooth communication of special vehicles. Based on the analysis of the unfair phenomenon in channel competition, the characteristics of node movement in vehicular network are combined. The algorithm synthetically considers the moving speed, direction and position of the node, adjusts the value of the competing window, assigns the priority of the corresponding channel access .4. through the simulation platform of NS2 and the node motion model generated by VanetMobiSim. The proposed two mechanisms are evaluated in terms of throughput, delay, link stability and fairness, and the effectiveness of the proposed two mechanisms is verified.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U463.67;U495

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