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Robust Sensor Bias Estimation for Ill-Conditioned Scenarios

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Tsinghua Science and Technology 2012年第3期17卷 319-323页

作者： Xiongjie Du Yue Wang xiuming shan Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

Sensor bias estimation is an inherent problem in multi-sensor data fusion systems. Classical methods such as the Generalized Least Squares （GLS） method can have numerical problems with ill-conditioned sets which are common in practical applications. This paper describes an azimuth-GLS method that provides a solution to the ill-conditioning problem while maintaining reasonable accuracy com- pared with the classical GLS method. The mean square error is given for both methods as a criterion to de- termine when to use this azimuth-GLS method. Furthermore, the separation boundary between the azi- muth-GLS favorable region and that of the GLS method is explicitly plotted. Extensive simulations show that the azimuth-GLS approach is preferable in most scenarios.

关键词： data fusion sensor bias estimation ill-conditioning

New theoretical framework for OFDM/CDMA systems with peak-limited nonlinearities

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Science in China(Series F) 2007年第5期50卷 783-792页

作者： WANG Jian ZHANG Lin shan xiuming REN Yong Department of Electronic Engineering Tsinghua University Beijing 100084 China

A new theoretical framework for the evaluation of the in-band nonlinear distortion effects on the performance of OFDM systems is presented. In contrast to previous works that approximate the nonlinear noise as a Gaussian additive random process, the new framework is based on the properties of the large deviations of a stationary Gaussian process and shot noise theories, which can evaluate the performance of the OFDM system with high accuracy, especially at realistic scenarios where the Gaussian approximation of the nonlinear noise is no longer valid. The approach can be used to evaluate many communication systems with peak-limited nonlinearities and high PAPR, such as the downlink performance analysis of large capacity DS-CDMA systems.

关键词： OFDM CDMA nonlinearities impulse noise

A topology control algorithm based on D-region fault tolerance

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Science China(Information Sciences) 2013年第7期56卷 33-41页

作者： SUN RuoZi WANG Yue YUAN Jian shan xiuming REN Yong Department of Electronic Engineering Tsinghua University Deparment of Applied Mathematics Harbin University of Science and Technology

In a wireless network, node failure due to either natural disasters or human intervention can cause network partitioning and other communication problems. For this reason, a wireless network should be fault tolerant. At present, most researchers use k-connectivity to measure fault tolerance, which requires the network to be connected after the failure of any up to k-1 nodes. However, wireless network node failures are usually spatially related, and particularly in military applications, nodes from the same limited area can fail together. As a metric of fault-tolerance, k-connectivity fails to capture the spatial relativity of faults and hardly satisfies the fault tolerance requirements of a wireless network design. In this paper, a new metric of fault-tolerance, termed D-region fault tolerance, is introduced to measure wireless network fault tolerance. A D-region fault tolerant network means that even after all the nodes have failed in a circular region with diameter D, it still remains connected. Based on D-region fault tolerance, we propose two fault-tolerant topology control algorithms--the global region fault tolerance algorithm (GRFT) and the localized region fault tolerance algorithm (LRFT). It is theoretically proven that both algorithms are able to generate a network with D-region fault tolerance. Simulation results indicate that with the same fault tolerance capabilities, networks based on both GRFT and LRFT algorithms have a lower transmission radius and lower logical degree.

关键词： fault tolerance connectivity spatial relativity topology control

Topology Control Algorithm Using Fault-Tolerant 1-Spanner for Wireless Ad Hoc Networks

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Tsinghua Science and Technology 2012年第2期17卷 186-193页

作者： Ruozi Sun Yue Wang Jian Yuan xiuming shan Yong Ren Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

A fault-tolerant 1-spanner is used to preserve all the minimum energy paths after node failures to cope with fault-tolerant topology control problems in wireless ad hoc networks. A fault-tolerant 1-spanner is a graph such that the remaining graph after node failures will not only remain connected, but also have a stretch factor of one. The fault-tolerant 1-spanner is used in a localized and distributed topology control algorithm, named the k-Fault-Tolerant 1-Spanner （k-FT1S）, where each node constructs a minimum energy path tree for every local failed node set. This paper proves that the topology constructed by k-FT1S is a k-fault-tolerant 1-spanner that can tolerate up to k node failures, such that the remaining network after node failures preserves all the minimum energy paths of the remaining network gained from the initial network by removing the same failed nodes. Simulations show that the remaining network after removal of any k nodes still has the optimal energy efficiency and is competitive in terms of average logical degree, average physical degree, and average transmission radius.

关键词： fault-tolerant spanner energy-efficiency topology control stretch factor

Joint admission control algorithm in access network

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Frontiers of Electrical and Electronic Engineering in China 2008年第2期3卷 150-154页

作者： Linwei shan Jian YUAN Yong REN xiuming shan Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

To deal with long probing delay and inaccurate probing results in the endpoint admission control method,a joint local and end-to-end admission control algorithm is proposed,which introduces local probing of access net-work besides end-to-end *** local probing,the algorithm accurately estimated the resource status of the access *** shows that this algorithm can improve admission control performance and reduce users’average waiting time when the access network is heavily loaded.

关键词： admission control quality of service manage-ment access network differentiated service

Weak key analysis for chaotic cipher based on randomness properties

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Science China(Information Sciences) 2012年第5期55卷 1162-1171页

作者： YIN RuMing,WANG Jian,YUAN Jian,shan xiuming & WANG XiQin Department of Electronic Engineering,Tsinghua University,Beijing 100084,China 1. Department of Electronic Engineering Tsinghua University Beijing 100084 China

Weak key analysis is a key issue in the design of chaotic *** most of the existing research focusing on the degradation of the chaotic sequences which causes weak keys,we point out that the parameters for which the chaotic sequences do not degrade are still possible to be weak *** this paper,we propose a new approach based on the rigorous statistical test to improve the weak key *** weak keys of a specific chaotic cipher are investigated by using our method and a large number of new weak keys are *** results verify that our method is more *** the other hand,although statistical tests are now widely adopted to test the chaos-based bit sequences,there are few reports of analysis results on the weak keys or weak sequences of chaotic *** our work may be helpful for current research on statistical tests of chaotic cipher.

关键词： chaos cryptography statistical test weak keys sequence randomness

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基于SIP的域间网络会议安全框架

计算机工程 2006年第14期32卷 127-129页

作者：单琳伟山秀明任勇清华大学电子工程系北京100084

多媒体网络会议是一类重要的网络应用,为网络会议提供安全支持是一项必要的工作。该文介绍了会话初始协议(SIP)和域间网络会议模型,分析了网络会议安全框架的设计原则,提出了完整的安全框架,讨论了安全框架和网络会议管理功能的结合问题... 详细信息

多媒体网络会议是一类重要的网络应用,为网络会议提供安全支持是一项必要的工作。该文介绍了会话初始协议(SIP)和域间网络会议模型,分析了网络会议安全框架的设计原则,提出了完整的安全框架,讨论了安全框架和网络会议管理功能的结合问题,给出了一个信令流程实例。

关键词：会话初始协议网络会议安全框架

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基于一致关联数最大化的航迹关联算法

航空学报 2014年第11期35卷 3115-3122页

作者：田威王钺山秀明杨健清华大学电子工程系中国人民解放军91715部队

航迹关联(TTTA)是多传感器数据融合系统的核心模块之一,是系统误差估计和航迹融合的前提和基础。传感器存在的固有系统误差使得目标位置状态估计与真值发生偏离,容易诱发TTTA错误。传统的基于全局最小距离准则的TTTA算法,需要获得较高... 详细信息

航迹关联(TTTA)是多传感器数据融合系统的核心模块之一,是系统误差估计和航迹融合的前提和基础。传感器存在的固有系统误差使得目标位置状态估计与真值发生偏离,容易诱发TTTA错误。传统的基于全局最小距离准则的TTTA算法,需要获得较高精度的系统误差估计,来对航迹数据进行误差补偿。针对传感器具有系统误差环境下的TTTA问题,在对TTTA进行间接评估的基础上,定义了一致关联数的概念,提出了一致关联数最大化的TTTA准则,并在稳健交替迭代的框架下完成算法设计。与距离函数不同,一致关联数是一个离散量,放松了对系统误差估计精度的要求。最后,仿真实验验证了所提算法的有效性。

关键词：多传感器数据融合航迹关联系统误差全局最小距离错误关联一致关联数

An Overlay Network for Monitoring Activities of Computer Viruses

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Engineering Sciences 2008年第1期6卷 52-58页

作者： Li Ying Cao Yiqun Qiu Ben Jiao Jian shan xiuming Ren Yong School of Business SUN YAT-SEN University Guangzhou 510275 China Department of Electronic Engineering Tsinghua University Beijing 100084 China

To accurately track computer viruses,an overlay network that monitors the activities of viruses is *** and locating nodes infected by virus on network is achieved by a naming system in which a node in the network is mapped to a unique serial number of the *** carefully monitoring and recording sensitive communication between local system and remote nodes on the network,and suspicious operations on files that originate from remote nodes and entered via some form of file transfer,activities of viruses in both local and network level are recorded and ready for future *** data can also be used in analysis of the mechanism of a computer virus as well as its spreading mode and pattern.

关键词： overlay network virus observation DNS