面向城市场景的车辆自组织网络路由协议研究

发布时间：2018-08-25 07:45

【摘要】：车辆自组织网络(Vehicular Ad-hoc NETworks,VANETs)给人们日常生活带来了很多便利,是智能交通的重要组成部分,受到越来越多研究机构和人员的重视,逐渐成为一个非常重要的研究领域,近些年已经取得了许多有价值的研究成果。由于VANETs网络环境较复杂,网络拓扑具有高动态性,链路连接会频繁的中断,尤其是车辆密度小的情况下,网络的不连通概率更高,对于链路故障也很难预测,在移动终端之间建立完整可靠的端到端传输路径是很困难的。目前已有的基于地理的路由协议是VANETs中的主流路由协议,能较好的适应VANETs网络的高动态性,但这类协议仍然存在着两个方面的问题:问题一,节点位置信息不准确和链路质量不稳定;问题二,目前已有的地理路由协议几乎都是平面式的路由,而真实的VANETs城市场景是三维立体化的,将这些平面式路由应用于三维城市场景会使这些协议的性能受损。因此,研究适合VANETs这种特殊网络环境下的路由协议是亟需解决的一个重点难题。本文针对VANETs网络特点及以上提出的两个方面的问题,提出了两种路由协议——基于链路质量和节点实时位置估计的地理机会方向路由GOD和基于链路质量的分层道路路由协议LSHR。GOD协议主要应用于平面化的城市场景,采用机会路由思想,机会路由中,源节点并不是选择单一路径到目的节点,而是利用无线网络的广播特性,在源节点和目的节点之间选择许多潜在的中继节点,这类路由最大的优势是采用额外的备用链路,使更多的节点参与到数据转发过程中,提高了传输的可靠性。GOD选取转发节点集时综合考虑各邻节点到目的节点的实时距离、各邻节点与当前节点的运动方向及单条链路的投递率需求;对转发节点进行优先级排序时,综合考虑了各转发节点的运动方向,各转发节点与目的节点的实时距离,以及当前节点链路的ETX值,使得既离目的节点近,链路质量又好且不断靠近目的节点的节点优先转发数据包。LSHR是在分析城市场景三维特性的基础上提出的一种基于简单三维场景的路由协议,这里的简单三维场景指由两条或两条以上平行但具有不同高度的道路组成的场景。LSHR协议包括路口判决策略和分组传输策略两部分内容。路口判决时根据交叉口处节点提供的各相邻路段单位长度上的通信时延信息以及各对应交叉口到目的节点的距离,为每个相邻路口计算一个权值,然后选择计算结果最小的相邻路口作为数据包传输的下一个临时目的交叉口;分组传输时以优先选择两跳传输范围大的邻节点作为转发节点的原则进行分组的传送。在减少路由跳数降低传输时延的同时增加了分组的投递率,提高了通信链路的质量和路由的整体性能。
[Abstract]:The vehicle Ad Hoc Network (Vehicular Ad-hoc NETworks,VANETs) has brought a lot of convenience to people's daily life and is an important part of its. It has been paid more and more attention by more and more research institutions and personnel, and has gradually become a very important research field. In recent years, many valuable research results have been obtained. Because of the complexity of the VANETs network environment, the network topology is highly dynamic, the link connection will be interrupted frequently, especially in the case of small vehicle density, the disconnection probability of the network is higher, and it is difficult to predict the link failure. It is difficult to establish a complete and reliable end-to-end transmission path between mobile terminals. The existing geo-based routing protocols are the mainstream routing protocols in VANETs, which can better adapt to the high dynamic nature of VANETs networks. However, there are still two problems in this kind of protocols: first, The location information of nodes is inaccurate and the link quality is unstable. Second, most of the existing geographic routing protocols are planar routing, and the real VANETs urban scene is three-dimensional. The performance of these protocols will be compromised by applying these planar routes to three-dimensional urban scenarios. Therefore, it is an important problem to study the routing protocol suitable for the special network environment of VANETs. This paper aims at the characteristics of VANETs network and the two problems mentioned above. In this paper, two routing protocols, geo-opportunistic directional routing (GOD) based on link quality and real-time location estimation of nodes, and hierarchical road routing protocol (LSHR.GOD) based on link quality are proposed. In opportunistic routing, the source node does not choose a single path to the destination node, but selects many potential relay nodes between the source node and the destination node by using the broadcast characteristics of the wireless network. The biggest advantage of this kind of routing is the use of extra standby links to enable more nodes to participate in the process of data forwarding. The reliability of transmission is improved. When selecting the set of forwarding nodes, the real-time distance from each neighbor node to the destination node is considered synthetically. The moving direction of each neighbor node and the current node and the demand of single link delivery rate. When priority ranking is carried out on the forwarding node, the movement direction of each forwarding node and the real-time distance between each forwarding node and the destination node are considered synthetically. And the ETX value of the current node link, which makes it close to the destination node, LSHR is a routing protocol based on simple 3D scene, which is based on the analysis of 3D characteristics of urban scene. The simple 3D scene here refers to scenario. LSHR consists of two or more parallel but different height roads. LSHR protocol includes two parts: intersection decision strategy and packet transmission strategy. According to the communication delay information on the unit length of each adjacent road section and the distance from each corresponding intersection to the destination node, a weight value is calculated for each adjacent intersection when the intersection is judged. Then the adjacent intersection with the smallest calculation result is selected as the next temporary destination intersection for packet transmission, and the packet transmission is based on the principle that the neighbor node with a wide range of two hops is selected as the forwarding node in priority in packet transmission. While reducing the number of hops and reducing the transmission delay, the packet delivery rate is increased, and the quality of the communication link and the overall performance of the routing are improved.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U495;TN929.5;TP391.44

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