【作者】 肖鹏；

【导师】 符云清；

【作者基本信息】 重庆大学 ， 计算机系统结构， 2010， 硕士

【摘要】 近年来,随着无线通信技术的发展,移动自组网的研究成为了热点。移动自组网是由多个带有无线收发装置的移动节点组成的一个多跳的、没有中心节点和固定基站的自治网络系统。在这种网络中,各节点间的相互通信通常需要其他节点进行协助才能完成。在传统的移动自组网路由协议中,主要是基于节点间的链路是对称这样的假设来进行设计的。即所有节点有相同的信号覆盖范围。然而,对于现实的无线网络环境,各节点由于自身功率不同,往往造成非对称链路的存在。这就造成已有的路由协议不能较好适应这种情况。因此,设计适合非对称链路的无线移动自组网路由协议,对于移动自组网的发展有着重要的现实需求和学术意义。本文针对目前移动组网路由协议的不足,对AODV协议进行改进,提出了能够适应存在非对称链路的无线移动自组网路由协议。为了实现研究目标,本文围绕移动自组网的路由策略问题展开研究。首先叙述了移动自组网的三种路由模式:先应式路由、后应式路由和混合式路由。并分别介绍了这三种路由模式的经典路由协议DSDV、AODV、ZRP,同时对这三个协议进行了优缺点分析;在第三章,指出在移动自组网环境中,非对称链路的普遍存在,并分析了它的产生原因,以及对网络的影响;在第四章,我们给出了一种适合非对称链路的无线移动自组网按需路由协议。该协议通过在路由请求报文和路由应答报文中携带经过的路径节点来发现前向路由和后向路由,并在路由发现过程中计算链路权值。如果找到的路由是纯双向链路,则该路由发现过程成为为近似AODV路由协议的路由发现过程。如果找到的路由不是纯双向链路,则源节点还需要将RACK报文沿找到的回路路由循环一次,通过RACK的传播来通知中间节点建立起相应的路由。对于路由维护,本文提出了完整的存在单向链路情况下的链路终断检测方案。提出了路径关联节点表,使得路由维护过程更加适用于非对称链路环境。最后,本文对该路由算法的性能进行了仿真分析,并与AODV协议,AODV-H协议和RODA协议进行对比。实验结果表明,本文提出的路由协议能较好适用于非对称链路无线移动自组网环境。更多还原

【Abstract】 In recent years, with the development of wireless communication technology, the study of mobile ad hoc networks has been more and more popular. Mobile ad hoc networks is a kind of multi-hop and autonomous network system without central node and fixed base station, composed by a number of mobile nodes with wireless transceiver devices.In such a network, the communication between the nodes usually needs other nodes’assistance. The traditional routing protocols for mobile ad hoc networks are mainly designed on the base of the hypothesis that the links between nodes are symmetrical links. It means that all nodes have the same transmission range. However, the different power of nodes usally causes the existence of asymmetric links in real wireless network. Which will cause the existing routing protocols cannot better suit for this situation. Therefore, our research has the very practical demand and academic significance.In this text, we make several improvements for AODV and give the routing protocol adapting to the MANET with asymmetric links. In order to achieve the object, we carry out studies surrounding the mobile ad hoc routing strategy. Firstly, we introduce the three types of routing protocols for mobile ad hoc network: proactive routing protocols, reactive routing protocols,hybrid routing protocols.We introduc DSDV, AODV and ZRP of the classical routing protocols for the three types and analyze their merits and drawbacks.In chapter 3, we give the opinion that there are asymmetric links in real MANET.Then,we analyze the factors of its exists and its influences in networks.In chapter 4,we put forward an on-demand routing protocol for mobile ad hoc with asymmetric links. The routing protocol use RREQ (request message) and RREP (response message) to search the forward route and backward route.In the route discovery phase, RREQ and RREP will record the nodes which relay it and compute the weights of the links. If the route is a pure two-way path, the routing finding process will become an approximate AODV. If it is not a pure two-way path which includes some asymmetric links, the source needs to spread the RACK along the route and inform the route-related nodes to establish the corresponding route. For the route maintenance, we give a complete scheme of detecing link for MANET with asymmetric links. We propose route-related nodes table.It makes route maintenance better for the suitation with asymmetric links.Finally; we conduct simulation and analysis against performance of the routing algorithms and make the comparison with three protocols, including AODV, AODV-H and RODA. The experiment results show that the proposed routing protocol is fit on mobile Ad hoc networks with asymmetric links.更多还原