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| 有限自治域网络节点状态独立性研究 |
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王春芳1,2, 王毓晗1,2, 马正新1,2, 刘序明1,2
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1.微波与数字通信国家重点实验室,北京,100084;2.清华大学,电子工程系,北京,100084
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| 摘要: |
| 以节点延时为状态研究路由问题是网络路由研究的一个方向,这类问题的研究过程经常假设节点状态是独立的.这一假设为以延时为约束条件的路由问题,特别是以节点延时的概率密度函数为状态信息的QoS路由问题提供了一种较为实际的处理手段.探讨了在节点个数有限的自治域网络(简称有限自治域网络)中,各节点状态具有独立性这一假设的合理性,并通过网络仿真对其合理性进行了验证.在仿真过程中,实际测量了网络中60条链路延时和15条路径延时的概率密度函数.然后,基于独立性假设,用相应链路延时概率密度函数的卷积计算这15条路径延时的概率 |
| 关键词: 节点状态 节点延时 概率密度函数 独立性假设 方向散度 |
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| 基金项目:Supported by the National High-Tech Research and Development Plan of China under Grant No.2001AA121062(国家高技术研究发展计划(863)) |
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| Research on Node-State Independence in Autonomous Systems with Limited Node Number |
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WANG Chun-Fang,WANG Yu-Han,MA Zheng-Xin,LIU Xu-Ming
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| Abstract: |
| QoS routing based on node-delay information is an active research area these years. When delay is used as node state, it is often assumed that the state between each node is independent. Node-State independence assumption can provide a more tractable solution to delay constrained routing, especially when state information is Probability Density Function (PDF) of delay at each node. In this paper, the effectiveness of node-state independence assumption in Autonomous Systems with limited node number is investigated, and the conclusion is verified through vast simulation, whereas 60 link-delay PDFs and 15 path-delay PDFs in the network are observed. The 15 path-delay PDFs are also calculated by convolving the PDFs of contributing link-delays based on independence assumption. The statistical distance between the two sets of path-delay PDFs is measured by calculating divergence and comparing their delay expectation, variation and loss probability. Simulation and analysis results indicate that for Autonomous Systems with limited node number, node-state independence assumption is reasonable and path metrics calculated based on this assumption approximates well the original values and can be used in QoS routing. |
| Key words: node-state node-delay probability density function independence assumption divergence |
