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1st International Conference on Internet Multimedia Computing and Service, ICIMCS 2009

作者： Gong, Liyu Wang, Tianjiang Yu, Yan Liu, Fang Hu, Xiangen Intelligent and Distributed Computing Lab. School of Computer Science and Technology Huazhong University of Science and Technology Wuhan Hubei 430074 China Department of Information and Computing Science School of Science Wuhan University of Science and Technology Wuhan Hubei 430065 China Department of Psychology Institute for Intelligent Systems University of Memphis Memphis TN 38152 United States

ISBN: (纸本)9781605588407

In this paper, we propose a novel method to measure the distance between two Gaussian Mixture Models. The proposed distance measure is based on the minimum cost that must paid to transform from one Gaussian Mixture Model into the other. We parameterize the components of a Gaussian Mixture Model which are Gaussian probability density functions (pdf) as positive definite lower triangular transformation matrices. Then we identify that Gaussian pdfs form a Lie group. Based on Lie group theory, the geodesic length can be used to measure the minimum cost that must paid to transform from one Gaussian pdf into the other. Combining geodesic length with the earth mover's distance, we propose the Lie group earth mover's distance for Gaussian Mixture Models. We test our distance measure in image retrieval. The experimental results indicate that our distance measure is more effective than other measures including the Kullback-Liebler divergence. Copyright 2009 ACM.

关键词： Probability density function

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Improving performance bounds in feed-forward networks by paying multiplexing only once

Improving performance bounds in feed-forward networks by pay...

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2008 14th GI/ITG Conference on Measuring, Modelling and Evaluation of computer and Communication systems, MMB 2008

作者： Schmitt, Jens B. Zdarsky, Frank A. Martinovic, Ivan Disco Distributed Computer Systems Lab University of Kaiserslautern Germany

ISBN: (纸本)9783800730902

Bounding performance characteristics in communication networks is an important and interesting issue. In this study we assume uncertainty about the way different flows in a network are multiplexed, we even drop the common FIFO assumption. Under so-called arbitrary multiplexing we derive new bounds for the tractable, yet non-trivial case of feed-forward networks. This is accomplished for pragmatic, but general traffic and server models using network calculus. In particular, we derive an end-to-end service curve for a flow of interest under arbitrary multiplexing, establishing what we call the pay multiplexing only once principle. Finally, we present some numerical results to compare our bounds against the best known bounds for networks of arbitrary multiplexing nodes.

关键词： Calculations

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Placing multiple sinks in time-sensitive Wireless Sensor Networks using a Genetic Algorithm

Placing multiple sinks in time-sensitive Wireless Sensor Net...

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2008 14th GI/ITG Conference on Measuring, Modelling and Evaluation of computer and Communication systems, MMB 2008

作者： Poe, Wint Yi Schmitt, Jens B. Disco - Distributed Computer Systems Lab University of Kaiserslautern Germany

ISBN: (纸本)9783800730902

Performance issues in Wireless Sensor Networks (WSNs) play a vital role in many applications. Often the maximum allowable message transfer delay must be bounded in order to enable time-sensitive applications of WSNs like fire or intrusion detection systems. Hence, it is crucial to develop algorithms that minimize the worst-case delay in WSNs. In this work, we focus on the problem of placing multiple sinks such that the maximum worst-case delay is minimized while keeping the energy consumption as low as possible. For that purpose we develop an algorithm based on the Genetic Algorithm (GA) paradigm. To model and consequently control the worst-case delay of a given WSN we build upon the so-called sensor network calculus (a recent methodology introduced in [10]). In order to be able to assess the performance of the GA-based sink placement strategy we compare it to an exhaustive search algorithm as well as a Monte-Carlo search. All of the strategies are based on a discretization of the originally continuous search space into a finite search space, which forms a contribution of our work of independent interest. In the performance comparison with the other strategies the GA exhibits a favourable behaviour with respect to the quality of the solutions found and the computational effort invested. It thus seems to be a good candidate for addressing the problem of placing multiple sinks in large-scale time-sensitive WSNs.

关键词： Genetic algorithms

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Network calculus - What it can do for you and where it needs your help 08

Network calculus - What it can do for you and where it needs...

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4th Asian Internet Engineering Conference, AINTEC 2008

作者： Schmitt, Jens B. Distributed Computer Systems Lab. Computer Science Department University of Kaiserslautern 67653 Kaiserslautern Germany

ISBN: (纸本)9781605581279

In this talk, the theory of network calculus is discussed from the point of view: (1) how powerful it is in applications as well as (2) what fundamental challenges it still faces before it can be considered a similarly mature theory as the well-known classical queueing theory. To this end, we briefly review the basic concepts and mathematical foundations of network calculus, before we then show its applicability for the example of wireless sensor networks. The latter work culminated in the so-called sensor network calculus which is a customized and adequately extended set of methods based on the fundamental network calculus results enriched by the requirements stemming from the specific nature of wireless sensor networks. The lessons learned from this exercise are: on the one hand, network calculus provides already a rich and useful set of methods, but on the other hand, substantial work was still necessary to apply it to the particular context of wireless sensor networks (and to some degree still remains). Hence, in the second part of this talk, we outline some of the fundamental open issues with respect to the foundations of network calculus. We discuss current efforts to address these, although some of them are still completely open and thus constitute good opportunities for future research. Copyright 2008 ACM.

关键词： Wireless sensor networks

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Placing Multiple Sinks in Time-Sensitive Wireless Sensor Networks using a Genetic Algorithm

Placing Multiple Sinks in Time-Sensitive Wireless Sensor Net...

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GI/ITG Conference on Measuring, Modelling and Evaluation of computer and Communication systems

作者： Wint Yi Poe Jens B. Schmitt Distributed Computer Systems Lab University of Kaiserslautern Germany

关键词： Wireless Sensor Networks Optimal Sink Placement Genetic Algorithm Network Calculus Worst-Case Delay

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Improving Performance Bounds in Feed-Forward Networks by Paying Multiplexing Only Once

Improving Performance Bounds in Feed-Forward Networks by Pay...

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14th GI/ITG Conference - Measurement, Modelling and Evalutation of computer and Communication systems

作者： Jens B. Schmitt Frank A. Zdarsky Ivan Martinovic Distributed Computer Systems Lab University of Kaiserslautern Germany

关键词： Multiplexing Calculus Delay Aggregates Convolution Network topology Topology

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Towards multi-perspective intelligent layout design for context-driven route navigation

Towards multi-perspective intelligent layout design for cont...

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EMS 2008, European Modelling Symposium, 2nd UKSim European Symposium on computer Modelling and Simulation

作者： Anya, Obinna Tawfik, Hissam Nagar, Atulya Intelligent and Distributed Systems Lab. Deanery of Business and Computer Science Liverpool Hope University Liverpool L16 9JD United Kingdom

ISBN: (纸本)9780769533254

With the growing research interest in intelligent pervasive environments, there is a need to plan our layouts with sufficient criteria modelling so as to provide support for context-driven route navigation. However, current spatial layout modelling and simulation tools are largely inadequate for the task required since they are based on manual and heuristic techniques and do not provide a rich resource of context that will very well reflect user-perceived models of a layout. In this paper, we present an initial proof of concept prototype of a multi-perspective intelligent layout design and analysis framework to support context-driven navigation. We aim to show that some of the ideas to emerge from the field of intelligent systems, HCI, semantic technologies and advanced simulation could be combined with novel techniques in GIS-based information and image processing to analyse and visualise traffic networks and layouts from a range of design, travel and userrelated perspectives. © 2008 IEEE.

关键词： Intelligent systems

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Enabling authentic transmissions in WSNs — turning jamming against the attacker

Enabling authentic transmissions in WSNs — turning jamming ...

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IEEE Workshop on Secure Network Protocols (NPSec)

作者： Adam Bachorek Ivan Martinovic Jens B. Schmitt Disco Distributed Computer Systems Lab University of Kaiserslautern Germany

Traditional methods for message authentication are based on the cryptographic verification of received data using some sort of a shared secret. While this task is not critical for traditional networks, Wireless Sensor Networks (WSNs) may pay a high price for the gained protection - sensor nodes are forced to invest their already scarce resources in receiving a message and executing cryptographic computations, only to discard the message afterwards in case of a failed authentication. This work introduces a different, crypto-free approach for enabling authenticated communication by leveraging peculiarities of wireless communication, in particular its broadcast nature and the feasibility of channel capacity jamming. Instead of receiving and then verifying transmitted data, sensor nodes are prevented from receiving fake data at all. This is achieved by coupling physical characteristics of signal propagation with legitimate transmissions. Such a coupling enables the detection and invalidation of impersonation attacks by using short jamming pulses emitted by surrounding WSN nodes. We justify this concept by designing a novel communication protocol explicitly integrating the jamming feature, and analyze factors which impact the efficiency of successful jamming, such as the frame length, transmission timing accuracy, and various other issues identified through extensive empirical measurements.

关键词： Jamming Timing Wireless sensor networks Receivers Wireless communication Cryptography Accuracy

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Firewalling wireless sensor networks: Security by wireless

Firewalling wireless sensor networks: Security by wireless

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Conference on Local computer Networks (LCN)

作者： Ivan Martinovic Nicos Gollan Jens B. Schmitt Disco-distributed computer systems lab University of Kaiserslautern Germany

Networked sensors and actuators for purposes from production monitoring and control to home automation are in increasing demand. Until recently, the main focus laid on wired systems, although their deployment requires careful planning and expensive infrastructure that may be difficult to install or modify. Hence, solutions based on wireless sensor networks (WSNs) are gaining popularity to reduce cost and simplify installation. Clearly, one of the key issues rising from the switch to wireless communication lies in security; while an air gap is among the most effective security measures in wired networks, wireless communication is not as easy to isolate from attack. In this paper, we propose a system leveraging the peculiarities of the wireless medium, such as the broadcast nature of wireless communication and the unpredictability of indoor signal propagation to achieve effective protection against attacks based on the injection of fake data. Using a real-world WSN deployment and a realistic implementation of an attacker, we analyze this protection scheme and demonstrate that neither position change, transmission power manipulation, nor complete knowledge of wireless parameters can help an attacker to successfully attack the network. As a result, this work demonstrates how the chaotic nature of radio communication, which is often considered a disadvantage in regard to security objectives, can be used to enhance protection and support implementation of lightweight security mechanisms.

关键词： Wireless sensor networks Wireless communication Sensors Security Communication system security Distance measurement Antenna measurements

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Loss temporal dependency characteristic inference in wireless sensor network

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Journal of Computational Information systems 2008年第5期4卷 2303-2308页

作者： Li, Yongjun Ji, Wenli Dai, Yafei Computer Networks and Distributed Systems Laboratory Peking University Beijing 100871 China School of Computer Science Northwestern Polytechnical University Xi'an 710072 China School of Communication Engineering Xi'an University of Science and Technology Xi'an 710075 China State Key Lab. for Adv. Opt. Commun Syst and Networks Beijing 1000871 China

The internal link loss characteristic inference has become an increasingly important issue for operating and evaluating a wireless sensor network. Due to the inherent stringent bandwidth and energy constraints, it is usually impractical to directly collect link loss statistical data from each node in sensor network. Here we consider the problem of inferring the internal link loss characteristics from end-to-end measurement. We use the Gilbert error model to model the sensor link losses, formulate the problem of link loss characteristics estimation as a Bayesian inference problem, and propose a Markov Chain Monte Carlo (MCMC) algorithm to solve it. The simulation shows that the link loss performance parameters can be inferred accurately, and the proposed algorithm scales well according to the sensor network size. © 2008 Binary Information Press.

关键词： Inference engines

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