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    DTN网络的延时模型分析

    • 摘要: DTN(delay-tolerant network)是从ad hoc, WSN(wireless sensor network)等自组织无线网络中抽象出来的一种网络模型.其典型特征是节点之间的链路间歇性中断且中断持续时间较长,以至于在任意时刻源节点和目的节点间可能不存在路径.人们对DTN的研究尤其是对路由机制的研究已经很深入,但是作为路由算法所依赖的重要信息——延时——的分析模型还没有建立起来.从DTN数据包的投递过程出发,建立起DTN的延时模型,并利用排队论的相关知识进行分析,找出系统中各特征参数之间的关系,给出一般的结论.并对某些情形进行仿真,实验的数据显示理论结果和仿真数据拟合的很好.

       

      Abstract: DTN (delay-tolerant network) is an abstract network model that comes from some mobile self-organized networks such as ad hoc, WSN (wireless sensor network), satellite networks, etc. Its main characteristic is that the links between nodes are volatile and may break down for a long time at any time, so the network always suffers from long time partitioning. Being different from ad hoc, the partitioning in DTN may last such a long time that it can't be assumed that a path exists between the source node and destination node in DTN. DTN is proposed to deal with these situations. As a network model, routing algorithm is the pivot problem in those such as system architecture, packet format, neighbor discovery, etc. There have been many studies on routing algorithm in DTN, but there is still no mathematical model to analyze the delay which is the most important metric in most routing protocols. In this paper the procedure of delivering a packet in one hop in DTN is studied, and then a model is constructed for analyzing this one-hop delay. Finally queuing theories are used to give some important results which show the relations between some parameters such as average delay, average queue length and traffic distribution etc. Simulations prove that the results match the simulation situation.

       

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