|Alternative Title||The Research and Application on Forwarding Mechanism in the Opportunistic Networks
|Place of Conferral||兰州
|Abstract||Ad hoc网络自上世纪诞生以来，虽然研究成果丰硕，却一直难以在实际应用中大量普及。其中一个重要的原因便是这类网络要求内在连通性，即假设网络是全连通的，节点可通过中间节点的转发以多跳的方式实现数据传输。然而在实际应用中往往会因为节点移动、物体阻挡、信号干扰、节点失效或能量受限等多种原因，使得节点之间常会由于断线而无法通信，进而导致网络被划分成若干个彼此无法通信的内连通区域。针对这一情况，机会网络的概念被提了出来。在机会网络中，网络节点因为各种原因被分割成多个孤立的连通区域，源节点和目的节点之间可能不存在一条端到端的路径，节点通过移动与其它节点相遇形成通信机会，并利用这种通信机会以节点之间的转发形式实现数据的传输。作为一种更为自然的组网方式，机会网络十分适合各种具备短距离通信能力的移动设备如无线传感器、车载智能设备和手持设备等的组网与应用。由机会网络的定义可知转发机制是机会网络的核心问题之一，即如何确定最为合适的下一跳节点。本文围绕这一问题主要开展了以下工作：1、提出了一种基于机会网络的分布式计算环境架构ON-DEC，描述了其工作流程，对其中的转发机制展开了详细探讨。首先分析了下行阶段的任务分发机制，提出了两种分发算法DWOF和DWF并进行了比较，证明了DWF算法更为高效。在此基础上，通过仿真实验进一步分析了DWF算法中消息拷贝数 与节点密度和网络迟延之间的关系。|
|Other Abstract||Since the ad hoc networking technology emerged from last century, there has been abundant research production which hardly been prevalent to implement in reality. The most important reason is that the ad hoc network could work unless with a complete connectivity condition, and the data can be forwarded via mid-nodes from source to destination. However, because of the network disconnecting frequently caused by movement of nodes, block of some other objects, signal interference, invalidation of nodes or energy limit, the network is often divided into several regions which cannot communicate each other but keeping link within them.Then the opportunistic network (Oppnet) was proposed for this situation. In the Oppnet, all of the nodes are divided into several isolated parts in which nodes can link each other. There might be no a whole existing path from source to destination. The only communication opportunity is created through the encounter among moving nodes, and then data could be transferred between two meeting nodes. Therefore, as a more natural manner of networking, the Oppnet is fit for networking and application of those mobile devices with capability of short-distance communication, for instance, wireless sensors, vehicular intelligent devices and hand devices.The forwarding mechanism is one of the key problems in Oppnet research, which means to choose the most reasonable mid-node for the next hop. The thesis mainly focuses on the aspect of this problem and has achieved the following work.1. A distributed computing environment which is called ON-DEC based on Oppnet was proposed to carry out distributed computing in many hand mobile devices. We described its work flow at first and analyze the dissemination method occurred during the down phase which includes two different way called DWOF and DWF respectively, and then we compared these two ways and proved DWF was more effective. Based on this result, we demonstrated the upper bound of value for k which could be used to control the number of copy of tasks.|
邓毓博. 机会网络中转发机制的理论研究与应用[D]. 兰州. 兰州大学,2011.
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