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International Conference on Intelligent Environments

作者： Tserpes, Konstantinos Jacovi, Michal Gardner, Michael Triantafillou, Anna Cohen, Benjamin Distributed Knowledge and Media Systems Lab. National Technical University of Athens Athens Greece IBM Research Lab. - Haifa Haifa Israel School of Computer Science and Electronic Engineering University of Essex Colchester United Kingdom Athens Technology Center Athens Greece

ISBN: (纸本)9780769541495

Intelligent Environments most commonly take a physical form such as homes, offices, hotels, restaurants, shops, that are equipped with advanced networked computer based systems, which enable better or new lifestyles for people. However, Intelligent Environments can also take the form of virtual online spaces such as SecondLife, which can both mimic the real world and provide functionalities which could not be provided in reality, such as advanced simulations and movement. There is the growing trend for people to spend more time in such virtual environments and, to these ends, this work in progress paper reports on a new project, +Spaces which is developing a range of virtual world tools for e-government applications, and presents some of the concepts and technical challenges involved in creating these intelligent virtual spaces for e-government. © 2010 IEEE.

关键词： Virtual reality

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Node deployment in large wireless sensor networks: Coverage, energy consumption, and worst-case delay 09

Node deployment in large wireless sensor networks: Coverage,...

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Asian Internet Engineeering Conference, AINTEC 2009

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

ISBN: (纸本)9781605586144

Node deployment is a fundamental issue to be solved in Wireless Sensor networks (WSNs). A proper node deployment scheme can reduce the complexity of problems in WSNs as, for example, routing, data fusion, communication, etc. Furthermore, it can extend the lifetime of WSNs by minimizing energy consumption. In this paper, we investigate random and deterministic node deployments for large-scale WSNs under the following performance metrics: coverage, energy consumption, and message transfer delay. We consider three competitors: a uniform random, a square grid, and a pattern-based Tri-Hexagon Tiling (THT) node deployment. A simple energy model is formulated to study energy consumption for each deployment strategy. Using basic geometry we propose a novel strategy for calculating the relative frequency of exactly k-covered points, which uses k-coverage maps, for both a square grid and THT. 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 [7]). Finally, we analyze tradeoffs between these performance metrics for each deployment strategy to show which strategy is preferable under what factors, e.g., the number of nodes. Copyright 2009 ACM.

关键词： Energy utilization

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Sink placement without location information in large-scale wireless sensor networks 09

Sink placement without location information in large-scale w...

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Asian Internet Engineeering Conference, AINTEC 2009

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

ISBN: (纸本)9781605586144

Wireless Sensor networks (WSN) comprise a large number of sensor nodes that possess scarce energy supplies. To minimize energy consumption and to consequently extend the lifetime of WSNs, we propose a local search technique for sink placement in WSNs. In addition, a proper sink placement plays a vital role in performance-sensitive WSN applications. Since it is not feasible for a sink to use global information, especially for large-scale WSNs, we introduce a self-organized sink placement (SOSP) strategy that combines the advantages of our previous works [7] and [8]. Besides, this paper is a substantial extension of [9]. The goal of this research is to provide a better sink placement strategy with a lower communication overhead. Avoiding the costly design of using the nodes' location information, each sink sets up its own group by communicating to its n-hop distance neighbors. While keeping the locally optimal placement, SOSP exhibits a better solution quality with respect to communication overhead and computational effort than previous solutions. To analyze performance issues, especially the worst-case delay of a given WSN, we use a methodology called sensor network calculus [10]. Copyright 2009 ACM.

关键词： Sensor nodes

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Security by wireless: Why play fairer than the attacker 09

Security by wireless: Why play fairer than the attacker

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Asian Internet Engineeering Conference, AINTEC 2009

作者： Martinovic, Ivan Disco / Distributed Computer Systems Lab. Computer Science Department University of Kaiserslautern 67653 Kaiserslautern Germany

ISBN: (纸本)9781605586144

Security in wireless networks is a notorious problem, suffering from the following dilemma: On the one hand, wireless medium access puts the attacker into a much better position, on the other hand wireless devices most often have resource deficiencies (processing, memory, energy) which make conventional attack countermeasures based on cryptographic solutions impractical. Though, there have been many approaches towards lightweight security for wireless networks, this dilemma always persists, at least for the low-cost sector, say, for example, sensor networks or RFIDs. So far the overwhelming majority of wireless security approaches followed a conventional security paradigm which abstracts the physical communication as a logical channel. We depart from this paradigm, and try to leverage from the physical characteristics of wireless communications as much as possible, thus bringing us again in equality of arms with the attacker. This we coined the security by wireless principle. In the talk, several incarnations of the security by wireless principle are presented. These are taken from WLAN as well as wireless sensor network scenarios and show for different security goals that security by wireless designs can lead to interesting security solutions. Copyright 2009 ACM.

关键词： Wireless sensor networks

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SemanticQA: Web-based ontology-driven question answering 09

SemanticQA: Web-based ontology-driven question answering

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24th Annual ACM Symposium on Applied Computing, SAC 2009

作者： Tartir, Samir McKnight, Bobby Arpinar, I. Budak Large-Scale Distributed Information Systems Lab. Department of Computer Science University of Georgia Athens GA 30602-7404 United States

ISBN: (纸本)9781605581668

The ability to ask specific question to the internet using natural language and receiving answers instead of documents is highly desired. Recent advancements in semantic web technologies make it possible to support such capability with more accuracy compared to existing non-semantic techniques. Using our expertise in ontology building and semantic search and discovery we designed an ontology-driven question answering system that extracts answers from web documents. This system processes natural language queries using a background ontology and finds possible answer(s) to the question from web documents. Copyright 2009 ACM.

关键词： Ontology

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XPM statistics in 100% pre-compensated WDM transmission for different modulation formats and transmission fibres

XPM statistics in 100% pre-compensated WDM transmission for ...

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2009 14th OptoElectronics and Communications Conference, OECC 2009

作者： Fan, Zhang State Key Lab. of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing 100871 China

XPM statistics in 100% pre-compensated WDM transmission depends on bit rates, transmission fibres and modulation formats. XPM in DPSK systems shows much less stochastic than that in OOK systems. © 2009 IEEE.

ISBN: (纸本)9781424441037

关键词： Stochastic systems

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A Lie group based Gaussian mixture model distance measure for multimedia comparison 09

A Lie group based Gaussian mixture model distance measure fo...

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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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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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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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Loss cumulate generating function inference and application in wireless sensor network

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Journal of Computational Information systems 2008年第4期4卷 1399-1407页

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 of sensors, it is usually impractical to directly monitor each node or link in wireless sensor network. We consider the problem of inferring the internal link loss characteristics from passive end-to-end measurement in this paper. Specifically, the link loss performance inference during the data aggregation is considered. Under the assumptions that the link losses are mutually independent, we elab.rate a bias corrected link loss Cumulant Generating Function (CGF) algorithm. The simulation results show that the internal link loss CGF can be inferred accurately comparable to the sampled internal link loss CGF. At the end of this paper, we apply the result of internal link loss CGF inference to identify the lossy link in sensor network.

关键词： Sensor nodes

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