【作者】 李鑫；

【导师】 孙延涛；

【作者基本信息】 北京交通大学 ， 计算机技术（专业学位）， 2022， 硕士

【摘要】 移动自组织网络(Mobile Ad Hoc Network,MANET)是由一组不需要基站等基础设施的移动节点组成,以自组织的方式进行动态组网,各节点独立的进行路由决策,并需要适应不断变化的拓扑结构,其在军事战争、抢险救灾等领域中应用广泛。随着无线通信技术的不断发展,人们对于网络质量的要求也越来越高,由于MANET分布式的特征,其在组网时受制于网络资源的局部可见性,难以根据全网状态信息提供最佳路由和效率最佳的资源利用。而软件定义网络(Software Defined Network,SDN)的集中控制思想为解决上述问题提供了新的思路。目前已有研究人员提出将SDN技术引入MANET,提出了软件定义移动自组织网络(Software Defined Mobile Ad Hoc Network,SDMANET)的概念,但是该技术尚不成熟,存在诸多亟待解决的问题,比如在节点不断移动的情况下不能保证通信的稳定性、资源利用率低,路由信息维护开销大等问题。本文立足于SDMANET中的组网技术,为上述问题提供解决策略,主要研究工作及创新点如下:首先,本文提出一种基于多模电台和骨干网优化的组网方法,SDN控制器通过带外控制信道与网络节点进行通信,进而对整个网络进行控制。为了提高信道利用率,本文采用集中式支配集方法选择具有支配地位的节点作为骨干节点,只有骨干节点与控制器建立控制连接。同时针对周期性重选骨干节点所造成的丢包率问题提出改进算法,以渐进式的方式进行骨干节点和普通节点身份的切换。为了避免骨干节点承载过多的控制消息,本文设计了普通节点选择骨干节点的负载均衡策略。实验结果表明该方法能够有效降低网络丢包率。其次,本文提出一种集中式路由方法,SDN控制器在收集全局拓扑信息和资源状态信息后进行路由计算,结合A*算法从链路稳定性和时延等方面对路由路径进行优化。另外,本文采用源路由方式下发流表以减少路由控制开销,并针对链路中断情况设计响应机制以提高网络的鲁棒性。最后,本文使用Riverbed仿真软件和RYU控制器搭建SDMANET仿真平台,对本文提出的集中式骨干网构建算法和路由方法进行有效性验证。仿真结果表明,该方法能够有效降低路由控制开销,并对时延、丢包率等网络性能有明显改善。更多还原

【Abstract】 Mobile Ad Hoc Network(MANET)is composed of a group of mobile nodes that do not require infrastructure such as base stations.It conducts dynamic networking in a selforganizing manner.Each node makes routing decisions independently and needs to adapt to constant changes of the topological structure.MANET is widely used in military warfare,emergency rescue,disaster relief and other fields.With the continuous development of wireless communication technology,the requirements for network quality are getting higher and higher.Due to the distributed characteristics of MANET,it is subject to the local visibility of network resources during networking,and it is difficult to provide the best routing and optimal resource utilization based on the status of the entire network.The centralized control idea of Software Defined Network(SDN)provides new ideas for solving the above problems.At present,researchers have proposed the introduction of SDN technology into MANET,and proposed the concept of Software Defined Mobile Ad Hoc Network(SDMANET).However,this technology is not yet mature and there are many problems to be solved urgently.For example,in case of constant movement of nodes communication stability cannnot be guaranteed,resource utilization is low,and routing information maintenance overhead is high.Based on the networking technology in SDMANET,this dissertation provides solutions to the above problems.The main research work and innovations are as follows:First,this dissertation proposes a networking method based on multi-mode radio and backbone network optimization.The SDN controller communicates with network nodes through an out-of-band control channel,and then controls the entire network.In order to improve the channel utilization,this dissertation adopts the centralized dominance set method to select the dominant node as the backbone node,and only the backbone node establishes a control connection with the controller.At the same time,an improved algorithm is proposed for the packet loss rate caused by periodic reselection of backbone nodes,and the identities of backbone nodes and ordinary nodes are switched in a gradual manner.In order to avoid the backbone nodes from carrying too many control messages,this dissertation designs a load balancing strategy in which ordinary nodes select backbone nodes.Experiments show that this method can effectively reduce the network packet loss rate.Secondly,this dissertation proposes a centralized routing method.The SDN controller performs routing calculations after collecting global topology information and resource status information,and combines the A* algorithm to optimize the routing path in terms of link stability and delay.In addition,this dissertation uses source routing to issue flow tables to reduce routing control overhead,and designs response mechanisms for link interruptions to improve the robustness of the network.Finally,this dissertation uses Riverbed simulation software and RYU controller to build an SDMANET simulation platform to verify the effectiveness of the centralized backbone network construction algorithm and routing method proposed in this dissertation.The simulation results show that this method can effectively reduce the routing control overhead and significantly improve the network performance such as delay and packet loss rate.更多还原