| 网络透视中延迟推理算法的研究和改进 |
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| 引用本文： | 李东,张乃樑,孙怡.网络透视中延迟推理算法的研究和改进[J].哈尔滨工业大学学报,2009,41(1):89-92. |
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| 作者姓名： | 李东 张乃樑 孙怡 |
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| 作者单位： | 李东,孙怡,LI Dong,SUN Yi(哈尔滨工业大学计算机科学与技术学院,哈尔滨,150001);张乃樑,ZHANG Nai-liang(武汉第二船舶设计研究所,武汉,430064)
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| 摘 要： | 针对许多情况下网络参数不能直接测量的问题,网络透视方法将网络测量与统计推理相结合,间接得到网络中的链路性能参数.针对链路延迟的测量,介绍了网络透视中的基本EM算法,在减小矢量搜索空间,减少在一个时间窗口内调用EM算法次数,利用前面时间窗口的计算结果来避免当前时间窗口的重复EM计算等3个方面提出了降低EM算法计算复杂性的方法,并综合这些方法得出了改进的EM算法.实验表明,使用改进后的算法得到的推理结果能很好地逼近真实结果,并且在效率上有明显的提高.
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| 关 键 词： | 网络透视 延迟推理 EM算法 网络测量 |
Research and improvement on delay inference algorithm in network tomography |
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| LI Dong,ZHANG Nai-liang,SUN Yi.Research and improvement on delay inference algorithm in network tomography[J].Journal of Harbin Institute of Technology,2009,41(1):89-92. |
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| Authors: | LI Dong ZHANG Nai-liang SUN Yi |
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| Affiliation: | 1(1.School of Computer Science and Technology,Harbin Institute of Technology,Harbin 150001,China;2.Wuhan Second Institute of Ship Design,Wuhan 430064,China) |
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| Abstract: | Aimed at the problem that the direct network measurement is infeasible in many situations,the network tomography method that combines network measurement with statistical inference is able to get network link characteristics indirectly.Focused on the link delay,the basic EM algorithm in network tomography is introduced at first.By shrinking the vector search space,reducing the number of EM execution in one time window,and adopting the result of similar EM execution in previous time window to avoid repeat execution,the computation of EM algorithm is reduced.Based on these methods,an improved EM(IEM) algorithm is proposed at last.Experimental results show that,the inference result obtained from the IEM algorithm can agree well with the real result,and the efficiency is improved significantly compared with the basic EM algorithm. |
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| Keywords: | network tomography delay inference EM algorithm network measurement |
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