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Simulating large-scale networks with analytical models

International Journal of Simulation: systems, Science and Technology 2005年第1-2期6卷 24-31页

作者： Scheidegger, Matthias Baumgartner, Florian Braun, Torsten Computer Networks and Distributed Systems Group Institute of Computer Science and Applied Mathematics University of Bern Neubrückstrasse 10 Bern Switzerland

Discrete-event simulation of computer networks has significant scalability issues, which makes simulating large-scale networks problematic. We propose a high-level abstraction modeling network domains, interdomain links and traffic with highly scalable analytical models, which is much more efficient but slightly less accurate than node-by-node models. Thus, simulation scenarios containing several ISP networks become feasible. We also propose a way to combine this modeling approach with traditional packet-based simulators and present some preliminary evaluation results of the concept. © 2005, UK Simulation Society. All right reserved.

关键词： Analytical models

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CSFS: A Java enabled network file storage system

CSFS: A Java enabled network file storage system

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作者： Hua, Han Yafei, Dai Xiaoming, Li Computer Networks and Distributed Systems Laboratory Department of Computer Science and Technology Peking University Beijing 100871 China

The CSFS (cryptographic storage file system) is a network file storage system that is suitable for a small-to-medium sized networks such as a campus network. In a CSFS, a lot of distributed file servers are organized in a star-liked architecture. File names are stored in a name server and file data are stored in distributed file servers. A CSFS has good scalability and is able to accommodate hundreds of file servers. We implemented a CSFS in pure Java and tested the system with a benchmark. The test results show that CSFS delivers acceptable performance for general file operations. Its performance of file upload and download is as efficient as FTP. It can support more than 450 concurrent online users. Copyright © 2005 John Wiley & Sons, Ltd.

关键词： File organization

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Simulative performance evaluation of a mobile peer-to-peer file-sharing system

Simulative performance evaluation of a mobile peer-to-peer f...

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Next Generation Internet networks, NGI 2005

作者： Hoßfeld, Tobias Tutschku, Kurt Andersen, Frank-Uwe De Meer, Hermann Oberender, Jens O. Department of Distributed Systems University of Würzburg Germany SIEMENS AG Berlin Germany Department of Computer Networks and Computer Communications University of Passau Germany

ISBN: (纸本)078038900X

Peer-to-Peer (P2P) file-sharing has become the killer application in the wired Internet and might also be highly attractive for mobile networks. In particular since UMTS operators are searching for new applications which do both: a) exploit the potential of the UMTS technology and b) motivate the user to adopt the new technology. In this work we are investigating the performance of an eDonkey-based mobile P2P file-sharing system by means of time-dynamic simulation. Mobile networks differ from wireline networks by the limited capacity of the radio link and the mobility of the users. P2P networks, in contrast, are overlays which consider the transport network in an abstract way. In a mobile environment, the question arises, whether the abstraction can be maintained and what will be the performance impact if there is any. We will show in detail how the mobile access technology (GPRS or UMTS), the churn behavior of mobile users, the file size of mobile specific content, and special infrastructure entities, such as a cache peer, influences the performance of the suggested mobile P2P file-sharing service. © 2005 IEEE.

关键词： distributed computer systems

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Speeding up fractal image compression by genetic algorithms

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MULTIDIMENSIONAL systems AND SIGNAL PROCESSING 2005年第2期16卷 217-236页

作者： Mohamed, F Aoued, B Department of Computer Science Evolutionary Engineering and Distributed Information Systems Laboratory EEDIS University of Sidi Bel-Abbès Algeria Department of Electronics Communications Networks Architectures and Multimedia Laboratory University of Sidi Bel Abbès Algeria

The main problem with all fractal compression implementation is execution time. Algorithms can spend hours to compress a single image. Most of the major variants of the standard algorithm for speeding up computation time have led to a bad-quality or a lower compression ratio. For example, the Fisher's [ 7] proposed classification pattern greatly accelerated the algorithm, but image quality was poor due to the search-space reduction imposed by the classification, which eleminates a lot of good solutions. By using genetic algorithms to address the problem, we optimize the domain blocks search. We explore all domain blocks present in the image but not in exhaustive way ( like a standard algorithm) and without omitting any possible block (solution) as a classification pattern does. A genetic algorithm is the unique method for satisfying these constraints. And it is a way to do be a random search because the genetic one is directed by fitness selection, which produces optimal solutions. Our goal in this work is to use a genetic algorithm to solve the IFS inverse problem and to build a fractal compression algorithm based on the genetic optimization of a domain blocks search. we have also implemented standard Barnsley algorithm, the Y. Fisher based on classification, and the genetic compression algorithm with quadtree partitioning. A population of transformations was evolved for each range block, and the result is compared with the standard Barnsely algorithm and the Fisher algorithm = based classification. We deduced an optimal set of values for the best parameters combination, and we can also specify the best combination for each desired criteria: best compression ratio, best image quality, or quick compression process. By running many test images, we experimentally found the following set of optimal values of all the algorithm parameters that ensure compromise between execution time and solutions optimality: Population size = 100, Maximum generations = 20, Crossover rat

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Enabling mobile Peer-to-Peer networking

Enabling mobile Peer-to-Peer networking

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First International Workshop of the EURO-NGI Network of Excellence

作者： Oberender, Jens O. Andersen, Frank-Uwe De Meer, Hermann Dedinski, Ivan Hoßfeld, Tobias Kappler, Cornelia Mäder, Andreas Tutschku, Kurt University of Passau Department of Computer Networks and Computer Communications Innstraße 33 94032 Passau Germany University of Würzburg Department of Distributed Systems Am Hubland 97074 Würzburg Germany SIEMENS AG Siemensdamm 62 13623 Berlin Germany

In this paper we present a P2P file-sharing architecture optimized for mobile networks. We discuss the applicability of current P2P techniques for resource access and mediation in the context of 2.5G/3G mobile networks. We investigate a mobile P2P architecture that is able to reconcile the decentralized operation of P2P file sharing with the interests of network operators, e. g. control and performance. The architecture is based on the popular eDonkey protocol and is enhanced by additional caching entities and a crawler. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Telecommunication networks

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Implementation of a cellular framework for spontaneous network establishment

Implementation of a cellular framework for spontaneous netwo...

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IEEE Conference on Wireless Communications and Networking

作者： M. Danzeisen T. Braun S. Winiker D. Rodellar Innovation Swisscom AG Bern Switzerland Computer Networks and Distributed Systems University of Bern Bern Switzerland

Wireless communication technologies enabled the possibility of building spontaneous networks between two or more users to exchange data. The problem in the establishment of such networks lies in the configuration that has to be agreed on and in the way the communicating parties can be identified. In prior publications we have presented our vision of convenient networking in a heterogeneous environment. In this paper, we describe an implementation that offers a dashboard-like tool, which can, with the help of a cellular network, ease the formation of spontaneous networks among heterogeneous nodes. Furthermore, the provided implementation is able to secure the acquired communication links in the spontaneous network and therefore protect the exchanged information against possible abuse.

关键词： Cellular networks Wireless LAN Communication channels Bluetooth Sections computer networks Communications technology Protection LAN interconnection Protocols

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M/sup 3/HN: an adaptive protocol for mobility management in multi-hop heterogeneous networks

M/sup 3/HN: an adaptive protocol for mobility management in ...

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IEEE Symposium on computers and Communications (ISCC)

作者： A. George A. Kumar Mobile Information Networks and Distributed Systems (MINDS) Lab Computer Engineering and Computer Science University of Louisville Louisville KY USA

One of the research challenges for 4G-wireless systems is the design of mobility management techniques that integrate cellular and ad-hoc networks. Currently there are no structured mobility management schemes for these heterogeneous multi-hop networks. In this paper we propose an adaptive protocol for mobility management in multi-hop heterogeneous networks (M/sup 3/HN) for seamless mobility in an integrated cellular and ad-hoc network. This paper describes techniques for tracking a mobile node in a multi-hop network with minimum overhead. Using M/sup 3/HN a node can migrate from a single-hop network to a multi-hop connectivity seamlessly. This scheme is independent of the routing protocol used in a multi-hop network.

关键词： Mobile radio mobility management Intelligent networks Spread spectrum communication Ad hoc networks Cellular networks Land mobile radio cellular systems Broadcasting Wireless application protocol Mobile computing computer networks

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An energy-aware medium-access-control protocol with frequent sleeps for wireless sensor networks

An energy-aware medium-access-control protocol with frequent...

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IEEE Symposium on computers and Communications (ISCC)

作者： C.K. Nguyen A. Kumar Mobile Information Networks & Distributed Systems (MINDS) Laboratory Department of Computer Engineering & Computer Science (CECS) University of Louisville Louisville KY USA

The paper proposes an energy-aware contention-based protocol for the medium access control (MAC) sub-layer for wireless sensor networks. The innovative approach with frequent sleeps proactively and aggressively reduces the wasted energy while increasing the throughput and decreasing the latency. The proposed MAC protocol solves the energy inefficiency caused by idle listening, control-packet overhead, and overhearing. Simulation experiments have been performed to demonstrate the effectiveness of the proposed approach, especially compared to the S-MAC and T-MAC protocols.

关键词： Wireless application protocol Wireless sensor networks Media Access Protocol Throughput Access protocols Delay Energy consumption Communication system control Communication channels

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Simulative performance evaluation of a mobile peer-to-peer file-sharing system

Simulative performance evaluation of a mobile peer-to-peer f...

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Conference on Next Generation Internet networks, NGI

作者： T. Hopfeld K. Tutschku F.-U. Andersen H. de Meer J.O. Oberender Dept. of Distributed Syst. Wurzburg Univ. Germany Department of Distributed Systems University of Wiirzburg Germany SIEMENS AG Berlin Germany Chair of Computer Networks and Computer Communications University of Passau Germany

Peer-to-peer (P2P) file-sharing has become the killer application in the wired Internet and might also be highly attractive for mobile networks. In particular since UMTS operators are searching for new applications which do both: a) exploit the potential of the UMTS technology and b) motivate the user to adopt the new technology. In this work we are investigating the performance of an eDonkey-based mobile P2P file-sharing system by means of time-dynamic simulation. Mobile networks differ from wireline networks by the limited capacity of the radio link and the mobility of the users. P2P networks, in contrast, are overlays which consider the transport network in an abstract way. In a mobile environment, the question arises, whether the abstraction can be maintained and what will be the performance impact if there is any. We will show in detail how the mobile access technology (GPRS or UMTS), the churn behavior of mobile users, the file size of mobile specific content, and special infrastructure entities, such as a cache peer, influences the performance of the suggested mobile P2P file-sharing service.

关键词： Peer to peer computing 3G mobile communication Telecommunication traffic Communication system traffic control computer networks Mobile communication Application software Radio link Ground penetrating radar Payloads

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9. Reliability and load balancing in distributed hash tables

9. Reliability and load balancing in distributed hash tables

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作者： Rieche, Simon Niedermayer, Heiko Götz, Stefan Wehrle, Klaus Universität Tübingen Protocol-Engineering and Distributed Systems Group Morgenstelle 10c 72076 Tübingen Germany Universität Tübingen Computer Networks and Internet Morgenstelle 10c 72076 Tübingen Germany

9.1 Storage Load Balancing of Data in distributed Hash Tables 9.1.1 Definitions 9.1.2 A Statistical Analysis 9.1.3 Algorithms for Load Balancing in DHTs 9.1.4 Comparison of Load-Balancing Approaches 9.2 Reliability of... 详细信息

ISBN: (纸本)354029192X

关键词： Redundancy

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