城市环境下基于地理位置的VANETs路由协议研究

发布时间：2019-06-04 02:58

【摘要】：车辆自组织网络(Vehiclular Ad Hoc Networks,VANETs)是移动自组织网络的一个极具应用价值的研究方向,也是智能交通系统领域的关键组成部分。VANETs以行驶的车辆和路边基础设施为节点,节点之间可以进行单跳或者多跳的通信,相互交换各自的节点信息,如节点速度和地理位置等,从而自发地形成一个Ad Hoc网络。借助GPS、车载的传感器等设备,车辆自组织网络可以很方便的获取节点的和道路的各种信息,给驾驶员提供导向、道路预警和网络接入等服务,不仅提高了驾驶员行驶的安全性,而且增加了驾驶舒适性。在城市道路环境中,网络拓扑变化频繁、节点移动受道路布局限制以及无线信号的传输受障碍物阻挡等问题,使得VANETs中需要设计出更加复杂的路由协议。因此,设计出符合城市道路环境下VANETs特点的路由协议是个难点。本文针对VANETs的特点,提出了一种基于路段长度的交叉路口路由协议。在该协议中根据节点的位置,节点被分为普通节点和交叉路口节点两种。该协议的大体思路是:当前节点的交叉路口邻居节点获取相邻路段的连通信息,如果存在连通的相邻路段,在这些交叉路口邻居节点中选择距离目的节点最近的作为下一跳;否则,下一跳节点就为当前节点邻居表中距离目的节点最近的节点,如此重复直到到达目的节点或者遇到局部最优问题。该协议中针对路段长度小于无线信号通信半径和路段长度大于无线信号通信半径两种情况,分别采用不同的方法判断路段的连通性。在路段长度小于无线信号通信半径时,通过相邻路段或者其延伸路段是否存在交叉路口邻居节点的邻居节点判断路段的连通性;在路段长度大于无线信号通信半径时,利用实时的分布式方法获取路段的连通性。针对城市环境中由于建筑物的阻挡造成的频繁网络中断问题,本文提出了一种基于人工蛛网的地理位置路由协议。该协议中源节点利用GPS等导航设备获得当前节点和目的节点的地理位置、速度等信息,利用蜘蛛搜索电子地图获取搜索区域内路段的拓扑信息和各交叉路口的地理位置信息。根据这些信息,源节点计算出到达目的节点的可行路径;然后,源节点根据收到的广播的各路段的连通、延迟和跳数等信息,计算各可行路径的权重值之和,从中选择最佳路径;最后,源节点沿着最佳路径发送数据包。如果遇到局部最优问题或者转发失败,当前节点重新进行计算,确定新的最佳路径。
[Abstract]:Vehicle ad hoc network (Vehiclular Ad Hoc Networks,VANETs) is a valuable research direction of mobile ad hoc network, and it is also a key component in the field of intelligent transportation system. VANETs takes the driving vehicle and roadside infrastructure as the node. Single-hop or multi-hop communication can be carried out between nodes, and their respective node information, such as node speed and geographical location, can be exchanged with each other, so that a Ad Hoc network can be formed spontaneously. With the help of GPS, on-board sensors and other equipment, the vehicle self-organizing network can easily obtain all kinds of information about nodes and roads, and provide drivers with services such as guidance, road early warning and network access. It not only improves the safety of the driver, but also increases the driving comfort. In the urban road environment, the network topology changes frequently, the node movement is limited by the road layout and the wireless signal transmission is blocked by obstacles, which makes it necessary to design a more complex routing protocol in VANETs. Therefore, it is difficult to design a routing protocol which accords with the characteristics of VANETs in urban road environment. According to the characteristics of VANETs, a intersection routing protocol based on section length is proposed in this paper. In this protocol, according to the position of the node, the node is divided into two kinds: the ordinary node and the intersection node. The general idea of the protocol is as follows: the neighbor node of the current node obtains the connectivity information of the adjacent sections, and if there are connected adjacent sections, the nearest neighbor node to the destination node is selected as the next hop. Otherwise, the next hop node is the nearest node to the destination node in the current node neighbor table, so repeated until the destination node is reached or the local optimal problem is encountered. In this protocol, the connectivity of the section is judged by different methods when the length of the section is less than the radius of the wireless signal communication and the length of the section is larger than the radius of the communication of the wireless signal. When the length of the section is less than the radius of wireless signal communication, the connectivity of the road section is judged by whether there are neighbor nodes at the intersection or whether there are neighbor nodes in the adjacent section or its extended section. When the length of the road section is larger than the communication radius of the wireless signal, the real-time distributed method is used to obtain the connectivity of the road section. In order to solve the problem of frequent network outages caused by the blocking of buildings in urban environment, a geographical location routing protocol based on artificial spider web is proposed in this paper. In this protocol, the source node uses GPS and other navigation devices to obtain the geographical location and speed of the current node and destination node, and the spider search electronic map is used to obtain the topological information of the road section in the search area and the geographical location information of each intersection. According to these information, the source node calculates the feasible path to the destination node. Then, according to the information such as connectivity, delay and hop number of each section of the broadcast, the source node calculates the sum of the weight values of each feasible path and selects the best path. Finally, the source node sends packets along the best path. If you encounter a local optimal problem or a forwarding failure, the current node recalculates to determine the new optimal path.
【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

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