基于NS2的AODV协议研究与改进

发布时间：2019-05-24 03:44

【摘要】：移动自组织网络(Mobile Ad Hoc network,MANET)作为一个无中心基站且节点随机移动的无线通信网络,其拓扑结构无规则变化以及节点能量有限的特性使得路由协议设计成为Ad Hoc网络中的关键问题。而作为Ad Hoc网络中按需路由协议的代表,AODV协议虽然能够在网络中迅速建立一条路由,但是由于节点能量有限并且拓扑结构频繁发生变化,建立的路由随时可能发生断裂,影响网络的性能,因此对AODV协议的研究显得非常有意义。论文首先对Ad Hoc网络路由协议的研究背景及发展现状进行了阐述;接着介绍了Ad Hoc网络路由协议的主要分类,并对不同分类下的参数和性能进行比较,然后对Ad Hoc网络中的按需距离矢量路由(Ad Hoc On-demand Distance Vector Routing,AODV)的帧格式和工作机制进行了比较细致的分析;最后对经典的AODV协议进行了改进。第一种方案,因为传统的AODV协议只有一条通信链路,当该条链路发生断裂后就需要重新执行路由发现过程,这将严重影响网络的性能。本文研究了智能选择主备份路由的AODV协议(Smart Selection of Primary and Backup for Ad Hoc On-Demand Distance Vector Routing,SSPB-AODV),通过增加一条备份路由,并且通过对历史数据进行分析,智能的选择切换路由还是修复路由:即对于主路由,当发生路由中断时,会根据历史数据选择局部修复还是切换到备份路由;而对于备份路由,在路由发生断开后,会根据历史数据选择是修复路由还是向源节点发出路由错误由源节点进行处理。在NS2下的仿真实验表明,SSPB算法提高了分组投递率,减少了端到端的时延、路由发起频率和路由开销。第二种方案,由于在Ad Hoc网络中,带宽和能量都是极其有限的,这就要求路由协议的设计要将能量和负载状况纳入考量范围。本文研究了一种基于跳数代价衡量能量及负载的AODV协议(Measure Energy and Load Based on Hop Cost,EL-AODV),把节点的剩余能量和负载以跳数代价的形式表示出来,并结合链路本身的跳数,选择总跳数最小的链路作为通信链路,这样减少了在剩余能量小且拥塞严重的节点上创建路由,优化了网络中的能量并均衡了网络中的负载,提高了网络的性能。根据NS2的仿真结果可得,EL-AODV协议提高了网络的分组投递率和节点的剩余能量,减少了端到端的时延和路由开销。
[Abstract]:Mobile ad hoc network (Mobile Ad Hoc network,MANET) as a wireless communication network with no central base station and random movement of nodes, The irregular change of topology and the limited energy of nodes make routing protocol design a key problem in Ad Hoc networks. As the representative of on-demand routing protocol in Ad Hoc network, AODV protocol can quickly establish a route in the network, but because of the limited energy of nodes and frequent changes in topology, the established route may break at any time. It affects the performance of the network, so the research on AODV protocol is very meaningful. Firstly, the research background and development status of Ad Hoc network routing protocol are described in this paper. Then the main classification of Ad Hoc network routing protocol is introduced, and the parameters and performance of different categories are compared, and then the on-demand distance vector routing (Ad Hoc On-demand Distance Vector Routing, in Ad Hoc network is compared. The frame format and working mechanism of AODV) are analyzed in detail. Finally, the classical AODV protocol is improved. The first scheme, because the traditional AODV protocol has only one communication link, needs to rerun the routing discovery process when the link breaks, which will seriously affect the performance of the network. In this paper, the AODV protocol (Smart Selection of Primary and Backup for Ad Hoc On-Demand Distance Vector Routing,SSPB-AODV, which intelligently selects the main backup route, is studied. By adding a backup route, and by analyzing the historical data, Intelligent choice of switching route or repair route: for the main route, when the route is interrupted, the local repair or switching to the backup route will be selected according to the historical data; For backup routing, after the route is disconnected, whether to fix the route or send a routing error to the source node is processed by the source node according to the historical data. The simulation results under NS2 show that the SSPB algorithm improves the packet delivery rate, reduces the end-to-end delay, routing initiation frequency and routing overhead. The second scheme, because the bandwidth and energy are extremely limited in Ad Hoc networks, requires the design of routing protocols to take energy and load conditions into account. In this paper, a AODV protocol (Measure Energy and Load Based on Hop Cost,EL-AODV based on hop cost to measure energy and load is studied, which represents the residual energy and load of nodes in the form of hop cost, and combines the hop number of the link itself. The link with the smallest total hops is selected as the communication link, which reduces the creation of routing on the nodes with small remaining energy and serious congestion, optimizes the energy in the network and balances the load in the network, and improves the performance of the network. According to the simulation results of NS2, the EL-AODV protocol improves the packet delivery rate and the residual energy of the nodes, and reduces the end-to-end delay and routing overhead.
【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】：TN929.5;TN915.04

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