移动自组网 AOMDV 协议

学校代码 分 类 号 密 学 级 号
10406 TP391.4 110085208006
ቤተ መጻሕፍቲ ባይዱ
题目
移动自组网 AOMDV 协议 改进研究
作者
任春利
学科、专业 指 导 教 师 申请学位日期
电子与通信工程 李洪烈 教授 2014 年 06 月 10 日
分类号：TP391.4
学校代码：10406 学号：110085208006
南昌航空大学 硕 士 学 位 论 文
（专业学位研究生）
移 动 自 组 网 AOMDV 协 议 改 进 研 究
硕士研究生： 导 师：
任春利 李洪烈 教授 徐新河 讲师
申请学位级别：硕士 学科、专业： 所在单位： 答辩日期： 电子与通信工程 南昌航空大学信息工程学院 2014 年 6 月
授予学位单位：南昌航空大学
I
Study on the improvement of AOMDV protocol in Mobile Ad Hoc Networks
A Dissertation Submitted for the Degree of Master On Electronics and Communication Engineering by Ren Chunli
Under the Supervision of Prof. Li Honglie, Xu Xinhe
School of Information Engineering Nanchang Hangkong University, Nanchang, China
June, 2014
II
摘要
移动自组网是一种没有中心节点、自组织的无线网络，其网络特性与传统的 无线网络及有线网络不同。对组建移动自组网来说，路由协议的地位至关重要。 移动自组网中拓扑不断发生变化，如何选择稳定的路由是首要考虑的问题。在研 发新的路由协议过程中，提高路由可靠性是研究的主要目标之一。本文对移动自 组网多径路由协议进行综合分析与研究，详细介绍多径路由的分类与基本构成， 论述多径路由的优势与不足，并指出目前研究面临的主要问题。 在移动自组网多径路由协议中，AOMDV 协议具有相对较好的性能，但它有 一个主要的缺点，即在选择一条路径时，跳数是其唯一考虑的特性参数，而忽略 路径的稳定性。在实际的无线通信环境中存在固有的信道衰落特性，对选定路由 的稳定性有较高的要求。为了更大程度地降低信道中信号衰落的影响，本文提出 一种应对衰落的 AOMDV 协议改进方案。该方案在路由寻找过程中，以结合了 AOMDV 协议中跳数准则的平均无衰时间（ANFD）作为度量来选择短而稳的路 径，而不是简单地选择最短的路径。这样就将路由稳定性和路径长度紧密结合在 一起，从而提高整体路由质量。在路由维护过程中，衰落发生之前，利用预测信 号强度来触发切换，降低源节点到目的节点连接中断率，并且断开链路的平均衰 落时间（AFD）被记录下来，一旦脱离衰落它仍可能被重新利用。 为论证 AOMDV 协议改进方案在提高网络性能方面的优越性，本文对其进 行理论分析。在建立的网络模型下，推导出一条路径与多条路径寿命的概率密度 函数,分析路由控制开销和网络吞吐量方面的性能。最后使用网络仿真器 NS2， 在设定的网络环境下，对 AOMDV 协议及其改进方案的性能进行仿真对比，验 证改进方案的优越性。通过分析仿真结果，可以发现 AOMDV 改进协议对网络 参数，比如数据包投递率、平均端到端时延、路由控制开销和网络吞吐量等的性 能提升效果显著。 关键词：移动自组网，多径路由，AOMDV 协议，ANFD 值,NS2 仿真器
I
Abstract
The Mobile Ad Hoc Network (MANET) is a non-center and self-organization network, whose feature is different from wired network and traditional wireless network. Routing protocol is one of the key technologies to realize MANET. The topology structure of MANET varies frequently, so the stability of the selected route is crucially important. How to improve the routing reliability is one of the main aims of the routing protocol research. In this paper, multipath routing protocols for MANET are studied in depth, and the classification and basic structure of multipath routing protocols is introduced in detail, and the advantages and the main problems of multipath routing research are discussed. In the multipath routing protocols of the MANET, AOMDV protocol performs well, but there is a shortcoming in the protocol. The only characteristic considered when choosing a path is the number of hops and path stability is ignored. There is an inherent characteristic of channel fading in real wireless communication environment, which presents a high demand on the stability of the selected route. In order to cope with the fading of channel effectively, an improved scheme of AOMDV protocol is proposed in this paper. In the route discovery process, ANFD is combined with the hop-count criterion from AOMDV to serve as a metric with which to select short but stable paths instead of simply choosing the shortest path. So, the improved scheme takes into account stability and length to improve overall path quality. In the route maintenance process, it uses predicted signal strength to trigger a handoff before a fade occurs, reducing the connection failure rate. The breaking link AFD is recorded, so that it maybe reutilize once out of the fade. In order to demonstrate the superiority of the improved scheme of AOMDV protocol, the theoretical analysis of the improved scheme is made in this paper. Under the established network model, the probability density functions of the lifetimes of a single path and multiple paths are derived and the performances in terms of routing control overhead and network throughput are analyzed. Finally, using the network simulator NS2, under the settings of network environment, a contrast is made with the performance of the AOMDV protocol and its improved scheme, verifying the superiority of the improved scheme. Simulation results show that the network