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International Conference on distributed Computing systems Workshop

作者： Leonard Barolli Fatos Xhafa Arjan Durresi Akio Koyama Department of Information and Communication Engineering Fukuoka Institute of Technology Fukuoka Japan Department of Languages and Informatics Systems Polytechnic University of Catalonia Barcelona Spain Department of Computer Science Louisiana State University Baton Rouge LA USA Department of Informatics Yamagata University Yonezawa Yamagata Japan

The mobile cellular systems are expected to support multiple services with guaranteed quality of service (QoS). However, the ability of wireless systems to accommodate expected growth of traffic load and broadband services is limited by available radio frequency spectrum. Call admission control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. To deal with these problems, in this paper, we propose a fuzzy CAC system. We compare the performance of the proposed system with shadow cluster concept (SCC). We evaluate by simulation the performance of the proposed system. The proposed system has a good behavior on deciding the number of accepted connections while keeping the QoS for serving connections.

关键词： Call admission control Land mobile radio cellular systems Quality of service Wireless networks Traffic control Electronic mail Bandwidth Cellular networks Telecommunication traffic Multimedia systems

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Monitoring the Internet evolution adaptation in heavily-visited search services

Monitoring the Internet evolution adaptation in heavily-visi...

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IEEE International Conference on systems, Man and Cybernetics

作者： loannis Anagnostopoulos Christos-Nikolaos Anagnostopoulos Manolis Wallace University of the Aegean Department of Information and Communication Systems Engineering Karlovassi Samos island Greece Department of Cultural Technology and Communications University of the Aegean Mytilene Leicestershire UK Department of Cultural Technology and Communications University of the Aegean Mytilene Lesvos island GREECE Department of Computer Science University of Indianapolis Athens GREECE

This paper proposes an innovative method of monitoring the ability of Internet search services to maintain new and up-to-date results in their directories. The method is based on capture-recapture experiments performed in real wildlife biological studies. After the necessary modifications needed for conducting similar experiments on the Web, a sixteen-week period of capture-recapture experiments was made over the caches of Google and MSN. During this period the birth as well as the survival rates of Google's and MSN's cached results were estimated based on the Pollock's robust design method. The paper provides the implementation details of the applied model along with its initial assessment. The experimental results showed that this approach can be applied as a method for measuring the ability of Internet search services in terms of maintaining new and up-to-date results in their caches.

关键词： Monitoring Web and internet services Evolution (biology) Search engines Animals Sampling methods Error correction Wildlife Robustness IEEE directories

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Using a Grid Platform for Enabling Real Time User Modeling in On-line Campus

Using a Grid Platform for Enabling Real Time User Modeling i...

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International Conference on Complex, Intelligent and Software Intensive systems, CISIS

作者： Santi Caballe Fatos Xhafa Thanasis Daradoumis Joan Esteve Leonard Barolli Arjan Durresi Universitat Oberta de Catalunya Barcelona Catalunya ES Dept. of Languages and Informatics Systems Polytechnic University of Catalonia Barcelona Spain Department of Computer Science Multimedia and Telecommunication Open University of Catalonia Barcelona Spain Department of Information and Communication Engineering Fukuoka Institute of Technology (FIT) Higashi-ku Fukuoka Japan Department of Computer Science Louisiana State University Baton Rouge LA USA

User modelling in on-line distance learning is an important research field focusing on two important aspects: describing and predicting students' actions and intentions as well as adapting the learning process to students' features, habits, preferences, and so on. The aim is to greatly stimulate and improve the learning experience. Indeed, on the one hand, students' intentions may change during the realization of learning activities and thus their actions evolve accordingly as the learning process moves forward. On the other hand, adaptive systems can effectively plan and design appropriate learning tasks according to students' features, habits and interests with the aim of facilitating the achievement of the learning goal. In this context, user modelling implies a continuous processing and analysis of user interaction data during long-term learning activities, which produces large and considerably complex information. As a consequence, processing this information is costly and could require computational capacity beyond that of a single computer. In this paper, we show how a grid approach can considerably decrease the processing time of log data of on-line distance educational Web-based systems. Our prototype is based on the master-worker paradigm and is implemented using a peer-to-peer platform running on the Planetlab nodes. The results of our study show the feasibility of using grid middleware to speed and scale up the processing of log data and thus achieve an efficient and dynamic user modeling in on-line distance learning

关键词： computer aided instruction Adaptive systems computer science Predictive models Context modeling Information analysis Peer to peer computing Software systems Application software Usability

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ON THE ASYMPTOTIC SUM-RATE IN 2×N×2 DUAL-HOP RELAYING WITH QUALITY BASED CHANNEL REPORTING AND RELAY SELECTION

ON THE ASYMPTOTIC SUM-RATE IN 2×N×2 DUAL-HOP RELAYING WITH...

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18th International Symposium on Personal, Indoor and Mobile Radio communications (PIMRC 2007), vol.6

作者： Eun-Hee Shin Dongwoo Kim Department of Electrical Engineering and Computer Science Hanyang University Ansan South Korea Department of Communication Systems KTH Kista Sweden

In this paper, we prove the asymptotic sum-rate growth like 2 log log N can be achieved in 2×N×2 dual-hop relaying systems with 2 transmit antennas at a base station (or a source), N≥2 single receive/transmit antenna relays and 2 destination users with a single antenna. The capacity is achieved when the base station transmits with zero-forcing beamforming and the relays that actively transmit are selected with semi-orthogonal relay selection principle. Since the base station should know the channel information to the relays, the feedback load grows prohibitively large if N→∞. To reduce the feedback load from the relays to the base station, we use quality-based channel state reporting (QBR). Numerical results show that the sum-rate achieved by N relays gets close to its multiuser counterpart if the amplifying gain at the relay is large. We also show how QBR is effective in reducing the feedback load when N is large.

关键词： Relays Base stations Transmitting antennas Receiving antennas Mobile antennas Array signal processing State feedback Downlink MIMO Land mobile radio

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REQUIREMENTS FOR AN EVENT-BASED SIMULATION PACKAGE FOR GRID systems

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Journal of Interconnection Networks 2007年第2期8卷 163-178页

作者： FATOS XHAFA JAVIER CARRETERO LEONARD BAROLLI ARJAN DURRESI Polytechnic University of Catalonia Department of Languages and Informatics Systems C/Jordi Girona 1-3 08034 Barcelona Spain . Polytechnic University of Catalonia Department of Computer Architecture C/Jordi Girona 1-3 08034 Barcelona Spain Department of Information and Communication Engineering Fukuoka Institute of Technology (FIT) 3-30-1 Wajiro-higashi Higashi-ku Fukuoka 811-0295 Japan Department of Computer Science Louisiana State University 298 Coates Hall Baton Rouge LA 70803 USA

In this paper we present a study on the requirements for the design and implementation of simulation packages for Grid systems. Grids are emerging as new distributed computing systems whose main objective is to manage and allocate geographically distributed computing resources to applications and users in an efficient and transparent manner. Grid systems are at present very difficult and complex to use for experimental studies of large-scale distributed applications. Although the field of simulation of distributed computing systems is mature, recent developments in large-scale distributed systems are raising needs not present in the simulation of the traditional distributed systems. Motivated by this, we present in this work a set of basic requirements that any simulation package for Grid computing should offer. This set of functionalities is obtained after a careful review of most important existing Grid simulation packages and includes new requirements not considered in such simulation packages. Based on the identified set of requirements, a Grid simulator is developed and exemplified for the Grid scheduling problem.

关键词： Grid systems event-based simulation requirements scheduling

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AN EXPERIMENTAL STUDY ON GENETIC ALGORITHMS FOR RESOURCE ALLOCATION ON GRID systems

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Journal of Interconnection Networks 2007年第4期8卷 427-443页

作者： FATOS XHAFA LEONARD BAROLLI ARJAN DURRESI Polytechnic University of Catalonia Department of Languages and Informatics Systems C/Jordi Girona 1-3 08034 Barcelona Spain Department of Information and Communication Engineering Fukuoka Institute of Technology (FIT) 3-30-1 Wajiro-higashi Higashi-ku Fukuoka 811-0295 Japan Department of Computer and Information Science Purdue University School of Science Indianapolis 723 W. Michigan St. SL 280M Indianapolis IN 46202 USA

Computational Grid (CG) is an emerging paradigm in which geographically distributed resources are logically unified as a computational unit. A challenging problem in such systems is the allocation of jobs to resources that minimizes both makespan and flowtime parameters. In this paper, we present an experimental study on Genetic Algorithms (GAs) for scheduling independents jobs to Grid resources based on two replacement strategies: Steady-State GA (SSGA) and Struggle GA (SGA). SSGA distinguishes for its accentuated convergence of the population that rapidly reaches good solutions though it is soon stagnated. The SGA is based on struggle replacement and adaptively maintains diverse population, reducing thus convergence rapidity. The experimental results, based on a benchmark simulation model, showed that SGA outperforms SSGA for moderate size instances. On the other hand, the time needed by the SGA to reach makespan values obtained by the SSGA rapidly increases as more jobs and machines are added to the Grid. Thus, for larger size instances, SGA is not able to improve the results of the SSGA. Finally, we also report and analyze flowtime values for the considered benchmark.

关键词： Resource allocation Genetic Algorithm Job Scheduling Computational Grids ETC Simulation model

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A distributed QoS Routing and CAC Framework: Performance Evaluation of Its SSRA and InterD Agents

A Distributed QoS Routing and CAC Framework: Performance Eva...

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International Conference on Complex, Intelligent and Software Intensive systems, CISIS

作者： Leonard Barolli Makoto Ikeda Arian Durresi Fatos Xhafa Akio Koyama Department of Information and Communication Engineering Fukuoka Institute of Technology Fukuoka Japan Graduate School of Engineering Fukuoka Institute of Technology Fukuoka Japan Department of Computer Science Louisiana State University Baton Rouge LA USA Department of Languages and Informatics Systems Polytechnic University of Catalonia Barcelona Spain Department of Informatics Yamagata University Yonezawa Yamagata Japan

In order to support multimedia communication, it is necessary to develop routing algorithms which use for routing more than one QoS parameters. This is because new services such as video on demand and remote meeting systems require better QoS. Also, for admission control of multimedia applications different QoS parameters should be considered. In our previous work, we proposed an intelligent routing and CAC strategy using cooperative agents. In this paper, we propose and evaluate the performance of SSRA algorithm and a GA-based InterD agent. Performace evaluation shows that proposed agents have a good behavior

关键词： Routing Quality of service Electronic mail Intelligent agent Competitive intelligence Fuzzy control Admission control Broadband communication Artificial intelligence Multimedia communication

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On Simulations in MAS Development Deriving Stochastic Models from Agent Implementations to Examine Self - Organizing Dynamics

On Simulations in MAS Development Deriving Stochastic Models...

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ITG/GI-Fachtagung, Kommunikation in Verteilten Systemen

作者： Jan Sudeikat Wolfgang Renz Distributed Systems and Information Systems Computer Science Department University of Hamburg Vogt-Kölln-Str. 30 22527 Germany Multimedia Systems Laboratory Department of Information and Electrical Engineering Hamburg University of Applied Sciences Berliner Tor 7 20099 Germany

The decomposition of a software system into a set of autonomous entities (agents) is a promising modeling approach to today's distributed applications. Agent interplay in these sets of agents, so-called Multi-agent systems (MAS), enables the rise of complex, i. e. self-organizing and emergent system dynamics. Engineers revise agent implementations and face the challenge to comprehend, validate and finally predict the resulting system-level behaviors. In this paper we discuss the usage of simulation models to assist engineers in examining MAS dynamics. Particularly, we show how stochastic transition systems can be inferred from agent implementations. The resulting models allow engineers to explore the stochastic processes that may underlay agent designs, facilitating both system design and validation as well as system optimization. We present tool support to assist model derivation from MAS implementations, following the established BDI agent architecture and exemplify its usage in a case study.

关键词： Mathematical model Equations Biological system modeling Markov processes Calculus Algebra

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PERFORMANCE EVALUATION OF REACTIVE AND PROACTIVE PROTOCOLS FOR AD-HOC SENSOR NETWORKS USING DIFFERENT RADIO MODELS

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Journal of Interconnection Networks 2007年第4期8卷 387-405页

作者： TAO YANG LEONARD BAROLLI MAKOTO IKEDA ARJAN DURRESI FATOS XHAFA Graduate School of Engineering Fukuoka Institute of Technology (FIT) 3-30-1 Wajiro-Higashi Higashi-Ku Fukuoka 811-0295 Japan Department of Information and Communication Engineering Fukuoka Institute of Technology (FIT) 3-30-1 Wajiro-Higashi Higashi-ku Fukuoka 811-0295 Japan Department of Computer and Information Science Indiana University Perdue University Indianapolis 723 W. Michigan Street SL 280 Indianapolis IN 46202 USA Polytechnic University of Catalonia Department of Languages and Informatics Systems C/Jordi Girona 1-3 08034 Barcelona Spain

In this paper, we consider the behavior of a wireless ad-hoc sensor network for different radio models. By means of simulations, we analyze the performance of three protocols: AODV, DSR, and DSDV considering two radio models TwoRayGround and Shadowing. In difference with other works, we generalize the type of radio model by allowing the path loss randomnesses to be present in the service environment of the network. We study the perceived Goodput and Depletion of the ad-hoc sensor network and compare the performance of three protocols for different scenarios. The simulation results confirm the fact that the shadowing phenomena, by destroying the regularity of the network, reduce the mean distance among nodes and at the same time increase the interference level and the latency of packet transmission. In particular, we found a maximum relative difference of 70%. On the other hand, for the proactive DSDV routing protocol the energy consumption rate seems to be independent of the radio model, at least for moderate size of the network (256 nodes). Also, we found that the packet delivery ratio of AODV and DSR routing protocols are more stable than DSDV protocol.

关键词： Sensor networks Sensor-actor networks Ad-hoc networks Radio models Reactive protocols Proactive protocols

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Real-time coordination of autonomous vehicles

Real-time coordination of autonomous vehicles

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ITSC 2006: 2006 IEEE Intelligent Transportation systems Conference

作者： Bouroche, Mélanie Hughes, Barbara Cahill, Vinny Distributed Systems Group Computer Science Department Trinity College Dublin

ISBN: (纸本)1424400945

Autonomous vehicles seem to be a promising approach to both reducing traffic congestion and improving road safety. However, for such vehicles to coexist safely, they will need to coordinate their behaviour to ensure that they do not collide with each other. This coordination will typically be based on (wireless) communication between vehicles and will need to satisfy stringent real-time constraints. However, real-time message delivery cannot be guaranteed in dynamic wireless networks which means that existing coordination models that rely on continuous connectivity cannot be employed. In this paper, we present a novel coordination model for autonomous vehicles that does not require continuous real-time connectivity between participants in order to ensure that system safety constraints are not violated. This coordination model builds on a real-time communication model for wireless networks that provides feedback to entities about the state of communication. The coordination model uses this feedback to ensure that vehicles always satisfy safety constraints, by adapting their behaviour when communication is degraded. We show that this model can be used to coordinate vehicles crossing an unsignalised junction. © 2006 IEEE.

关键词： Ground vehicles

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