【作者】 葛文英；

【导师】 李腊元；

【作者基本信息】 武汉理工大学 ， 计算机应用技术， 2007， 硕士

【摘要】 随着科技的发展，便携式计算机和掌上型电脑日益普遍，无线通信技术得到迅速发展。在某些场合，例如，战场上部队快速展开和推进、发生地震活水灾后的营救，需要一种不依赖于任何预先架设的网络设施的通信技术，Ad Hoc网络应运而生。Ad Hoc网络是移动网络的一种特殊形式，不需要固定的基站，由一组带有无线收发装置的自主的无线节点或终端通过相互合作形成的网络，是一种自创造、自组织和自管理的网络。在Ad Hoc网络中，每一个主机都必须同时作为路由器。而且网络中的节点可以任意移动，导致Ad Hoc网络拓扑结构不可预测的频繁变化，路由协议就承担起及时维护和重建路径的工作。由于Ad Hoc网络的特殊特性使得传统的距离向量和链路状态路由协议并不适用于拓扑结构高度动态变化Ad Hoc网络。自从1970年美国国防部高级研究规划署资助了一项特别的研究——分组无线网络开始，Ad Hoc移动网络的大量协议就在不断的开发和发展中。Ad Hoc网络路由机制必须适应网络三个不断变化的基本特征：移动节点的总体密度，节点到节点的拓扑，网络的使用模式。目前Ad Hoc网络的路由协议有表驱动路由协议和按需路由协议。从移动自组网的移动性，拓扑动态性，带宽受限，功率约束等特点来看，按需驱动路由更能适应移动Ad Hoc网络的需要。本文首先阐述了课题研究的意义、目的和国内外研究现状及发展趋势。然后基于无线移动自组织网的网络环境，对多种Ad Hoc网络路由协议进行分析比较。采用AODV路由协议作为网络层协议，并且改进了传统的AODV路由协议算法，形成了改进的OAODV路由协议算法。OAODV协议中，路由表添加了记录前两跳和后两跳的域。这样，在路由发现过程通过报文携带的信息，记录下路由及反向路由的前两跳信息。在发现断路需要进行局部修复时，断链处的下游节点发送修复信息到其前两跳。这样不仅增大了局部修复成功的概率，并且在发生断路后能快速修复，从而减少了端到端延迟，提高了数据报文的成功发送率。本文采用目前流行的仿真平台NS2，在此平台的基础上，实现了OAODV路由协议算法。通过仿真比较传统的AODV路由协议和改进的OAODV路由协议的性能，验证了OAODV协议算法的性能优于原AODV协议。更多还原

【Abstract】 With the development of science and technology, portable computer and palmtop computer are increasingly prevalent, and the wireless communication technology develops promptly. In some cases, for instance, the rapid expansion of the army in a war, the rescue after earthquake or flood, it needs one communication technology that needn’t depend on any network facility erected beforehand. Then Ad Hoc network emerge as the times require. Ad Hoc network is one special kind of mobile networks that don’t need fixed basestation. It’s a self-creation, self-organization and self-supervisory network that formed by the cooperation of a boodle of autonomic wireless nodes or terminals with wireless R-T units.In Ad Hoc network, every host must be a router at the same time. And nodes in the network could move discretionarily, which make the topology change frequently and the routing protocol be expected to reconstructing and maintaining routing path in time. Because of the highly dynamic variation of topology in Ad Hoc network, the conventional distance vector routing protocols and link status routing protocols are not suitable. Since 1970 year, DARPA subsidized one extraordinary research—Ad Hoc network, a lot of protocols of Ad Hoc are under exploitating and developing. The route mechanism of Ad Hoc network should conform to three basic features: the population density of mobile node, the topology of nodes, and the operating mode of network.There are two kind of routing protocols for Ad Hoc network: table-driven and on-demand routing protocol. Considering the mobility, dynamic of topology, bandwidth limitation and power restriction, on-demand routing protocols are more suitable for Ad Hoc network.The thesis firstly described the significance and its’ target, it also describes the current status of the schedule. And then through analyzing and comparing many routing protocols of Ad Hoc Network, an optimized protocol: OAODV is presented which is preformed by AODV routing protocol. Rout table in OAODV is extended by adding two fields to save the previous two hop and the next two hop. And then, according the discovery packets, marked down the previous two hop of the router and the reverse router. When break occurred and need to local repair, the downstream node of the break point send the repair packets to its previous two hop. Thus can not only increase the probability of success, also repair the router immediately which decreased the end-to-end delay and increased the data delivery ratio.Simulation with different scenes is completed based on NS2, the popular simulated formwork, and performance of OAODV is analyzed according the data obtained by simulation to show that it is superior to the AODV.This thesis is supported by National Natural Science Foundation of China (Projects No: 90304018, 60672137) and Specialized Research Fund for the Doctoral Program Foundation of Ministry of Education of China Under Gram (No. 20060497015 ).更多还原