1、 本科毕业论文 题 目： 一种无线网状网中的多接口 多路径路由协议 姓 名： 学 院：软件学院 系：软件工程 专 业：软件工程 年 级： 学 号： 指导教师（校内）： 职称： 指导教师（校外）： 职称： 年 月I 摘 要 近 几 年来，无线网状网 (无线 Mesh 网 )逐渐成为一个研究热点。 无线网状网是一种基于多跳路由、对等网络技术的新型网络 。该类型无线 网络的潜力使无线宽带数据连接成为一种可实施 的技术。 作为移动自组网的一 个特例，组成无线网状网基础设施的路由结点通常是非移动性的，因此它 们可以被认为是固定结点的。而作为无线网络，其特性与有线网存在很多方面的不同，这导致了现有有线网的
2、很多概念都无法直接移植到无线网状网中。这些特殊性质让无线网状网的研究领域十分宽广。 在无线网状网的组网框架中，内部数据是通过一个或者多个网关与外部因特网相连通的，因此无线网状网路由协议的设计就尤其重要。目前已经涌现了不少针对提高网内数据传输能力的研究成果。本文正是在前人的基础上，通过比较四种无线网状网路由类型，试图通过提出一种新的 基于多接口、多路径的类 AODV 式路由协议来提升网络内部数据传输能力。该协议称为 MMAODV。 这个新提出的协议通过动态生成并维护两条或者两条以上的数据传输路径以增加单位时间内的数据传输量。而各个路径之间以及路径内部节点间通信的频道竞争、信号干扰问题则通过动态分
3、配频道、多接口同时工作的最优化选择来予以避免。 本文的最后利用 NS2 平台对于新协议进行了仿真实验，并通过与 AODV 路由协议和其他类型的路由协议的对比验证了 MMAODV 在性能方面的提升。 关键词 ： 无线网状网 ； 动态路由协议； 多路径； 多接口； 多频道 II Multi-Interface and Multi-Path Ad hoc On-Demand Distance Vector Routing Protocol in WMNs Abstract In recent years, Wireless Mesh Network (WMN) becomes a popular t
4、opic. WMN is a novel network base on multi-hop routing and equivalent network technology. Its potential makes broadband wireless internet access possible and practical. As a special case of mobile ad hoc networks, nodes of WMNs have relative fixed position, thus they can be considered to be static.
5、And as a case of wireless networks, it is quite different from wired networks, thus lots of existing network notions can not be used in WMNs any more. These special characters cause many research issues in this area. In the framework of WMN, inner nodes communicate with internet through one or more
6、gateways. Consequently, routing protocol for WMN is very important. Nowadays, a large quantity of work on this area has established various routing protocols in WMNs to improve end-to-end throughput, and this thesis is one of them. We summarize the existing works, compare four types of WMN routing s
7、cenarios, and set up a novel dynamic scheme called Multi-Interface and Multi-Path Ad hoc On-Demand Distance Vector (MMAODV) Routing Protocol based on the effort above. The proposed protocol dynamically establishes and maintains two or more paths for data transmission to increase the throughput of th
8、e flow in a distributed manner. Dynamical channel assignment is incorporated to avoid channel competition and interference intra and/or inter paths. A simulation study on NS2（ Network Simulator） was performed in our work to evaluate the system performance in terms of throughput in our proposed proto
9、col comparing to AODV and other WMN routing protocols in different scenarios. Key Words: wireless mesh network; dynamic routing protocol; multi-path; multi-interface; multi-channel III 目 录 第 1 章 绪论 . 1 1.1 什么是无线网状网 . 1 1.2 无线网状网研究方向 . 2 1.3 路由协议设计要素 . 2 第 2 章 路由协议 理论对比 . 4 2.1 单接口与 单路径 . 4 2.2 多接口与
10、单路径 . 5 2.3 单接口与 多路径 . 6 2.4 多接口与 多路径 . 7 2.5 小结 . 8 第 3 章 相关的研究 . 9 3.1 AODV 路由协议 . 9 3.2 多频道 MAC 层与 Link 层协议 . 9 3.3 多频道路由协议 . 10 3.4 多路径路由协议 . 11 3.5 JMM 路由协议 . 11 第 4 章 MMAODV 协议 . 12 4.1 概述 . 12 4.2 前提假设 . 12 4.3 算法 . 12 4.3.1 预定义 . 12 4.3.2 路径搜索 . 13 4.3.3 建立反向路径 . 14 4.3.4 建立发送路径 . 14 4.3.5 多
11、路径维护 . 14 4.3.6 数据传输 . 15 4.4 算法实现 . 15 4.4.1 实现环境 . 15 4.4.2 拓扑模型 . 15 4.4.3 解决方案讨论 . 15 4.4.4 类 MeshRouter 的分析 . 17 4.4.5 路径生成实验 . 20 4.4.6 算法小结 . 21 IV 第 5 章 仿真 . 22 5.1 仿真环境 . 22 5.2 仿真结果与讨论 . 24 5.2.1 吞吐量的提高 . 24 5.2.2 与跳数相关的性能表现 . 25 5.2.3 在其他传输流干扰下的表现 . 26 5.3 仿真小结 . 28 第 6 章 总结与展望 . 29 致谢 .
12、31 参考文献 . 33 V Contents Chapter 1 Introduction . 1 1.1 What is Wireless Mesh Network (WMN) . 1 1.2 WMN Issues . 2 1.3 Key Elements of Routing Protocol Design . 2 Chapter 2 Comparison . 4 2.1 Single-Interface and Single-Path Scenario . 4 2.2 Multi-Interface and Single-Path Scenario . 5 2.3 Single-Int
13、erface and Multi-Path Scenario . 6 2.4 Multi-Interface and Multi-Path Scenario. 7 2.5 Summary. 8 Chapter 3 Related Work . 9 3.1 AODV Routing Protocol . 9 3.2 Multi-Channel MAC and Link Protocols . 9 3.3 Multi-Channel Routing Protocols .10 3.4 Multi-Path Routing Protocols . 11 3.5 JMM Protocol . 11 C
14、hapter 4 MMAODV Protocol . 12 4.1 Survey .12 4.2 Assumption .12 4.3 Algorithm .12 4.3.1 Predefinition.12 4.3.2 Path Discovery .13 4.3.3 Reverse Path Setup .14 4.3.4 Forward Path Setup .14 4.3.5 Multi-Path Maintenance .14 4.3.6 Data Transmission .15 4.4 Implementation .15 4.4.1 Environment .15 4.4.2
15、Topology Model .15 4.4.3 Issues .15 4.4.4 Class MeshRouter in the Demo .17 4.4.5 Path Discovery Experiments.20 4.4.6 Summary.21 VI Chapter 5 Simulation . 22 5.1 Environment .22 5.2 Result and Discuss .24 5.2.1 The Enhancement of Throughput .24 5.2.2 Performance related to Hops .25 5.2.3 Performance
16、against Interference from other Flow.26 5.3 Summary.28 Chapter 6 Conclusion . 29 Acknowledgement . 31 References . 33 1 Chapter 1 Introduction 1.1 What is Wireless Mesh Network (WMN)? Wireless Mesh Networks (WMNs) are believed to be a promising technology to offer broadband wireless access to the In
17、ternet and to build self-organized networks in places where wired infrastructure is not available or not worthy to deploy1. WMNs are dynamically self-organized and self-configured, with the mesh nodes in the network automatically establishing an ad hoc network and maintaining the mesh connectivity2.
18、 Mesh routers in WMNs could always be classified into two types, mesh routers and mesh client. The WMNs infrastructure is made up of mesh routers, and will be used by mesh clients. Usually, mesh routers are considered to be static and high power devices. I n t e r n e tFigure 1.1 Wireless Mesh Netwo
19、rk Architecture 2 1.2 WMN Issues The broadcast nature of the wireless medium cause many different issues of wireless networks to wired ones. They focus on each layer of WMNs, such as Routing, Fairness, MAC and Capacity, etc. One of the hottest research areas is Routing in network layer. Routing prot
20、ocols in WMNs are required to set up and maintaining the route from source node to the destination nodes. The route established has to reduce the collisions and interferences as much as possible among wireless communications in a limited area. There are some famous routing protocols existing, for ex
21、ample, AODV, DSR, etc. 1.3 Key Elements of Routing Protocol Design Many papers work on the improvement of routing protocols. Most of them are focus on the two key elements follow: Channel Competition Avoidance: Wireless communications in the same area using the same channel will course seriously col
22、lision and interferences. There become two problems if only one channel is used. First is the Exposed Terminal18. In case of a mesh node is transmitting data with others, no wireless communications in the transmitting channel will be admitted in its carry sensing area. Thus it limits the performance
23、 of the network. The second problem is Hidden Terminal9,18. Protocol Hidden Terminal causes collisions (always be solved by RTS/CTS System) and Physical Hidden Terminal (can not be solved by RTS/CTS System) causes interferences. Researchers implement multi-channel in order to avoid those two problem
24、s. Multi-channel assigns different channels to transmit data in a area so that different transmissions are parallel from others. Another notion has to be introduced here is Multi-Interface. Multi-Interface allows a node uses more than one antenna to receive or send data. As mentioned above, interfac
25、es using same channel in the same time is meaningless, consequently, interfaces are always allocated with different channels to achieve a 3 performance improvement. Thus in this thesis, Multi-Interface used this definition. Multi-path Enhancement: This is a distributed notion in transmitting data. M
26、ulti-path19 is a way of improving throughput. Using multi-path, each data flow is divided into several ones, and could be transmitted to destina tion concurrently, in order to achieve times of throughput than single flow. Base on the two key elements, most of the routing protocols could be classified into four scenarios which combine different channel and path using situation. The section follow will compares the performances between them, and then make the best choice from the evaluation.
