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OPNET Technologies © 2008 OPNET Technologies,
Inc. |
University: University of Twente,
Netherlands Using Bloom filters for service discovery and context awareness: For our research OPNET is being used by Fei Liu, M.Sc. and Ir.
Patrick Goering in the projects Context Aware Networking and Personal
Networks @ Home. Bloomfilters where introduced in as a hash coding
technique that provides a trade-off between space usage or hash size
and time needed to test the membership of a message in a given set of
messages. A small chance of false positives is allowed, that is a
message is not a member of the given set while the system claims it
probably is. A false positive might not be a big problem as long as the
chance is low enough. We want to apply bloomfilters in the service
discovery mechanisms used in above mentioned projects. OPNET is used to
verify the design of this service discovery mechanism as well as find
how well it performs. We want to further investigate the performance in
case of mobile users and/or services and compare the results obtained
in the simulator with analytical results to verify both. For our research, OPNET is being used by Robert Taniman, M.Sc. (and possibly some Master students working on related subject) in the project Full Service Access Networks using Multimode Fibre. The use for multimode fibre may lead to a cost-effective solution for broadband access networks. But using the conventional baseband transmission is not viable with multimode fibre for typical distances and expected bandwidt. In this reasearch, we investigate the use of multicarrier passband transmission on multimode fibre to overcome the aforementioned limitations. The physical link characteristics model is provided with our own code, while OPNET is used as the platform to assess the performance of our algorithm for the subcarrier assignment (resource allocation) in terms of achievable throughtputs and mean sojourn times, in comparison with other algorithms. We also would like to investigate the behavior of our link-layer protocol, currently under work, on OPNET platform. Resource sharing in Multihop Ad-Hoc networks: OPNET is being used by dr. Anne Remke for her research into modelling multihop ad-hoc networks. We are using the IEEE 802.11e differentiation mechanism for giving prioritized access to bottlenecks in multihop ad-hoc networks. Stations can become a bottleneck because they have to forward traffic flows for multiple other stations, whereas in the standard CSMA/CA mechanism they share the medium with these other stations on an equal basis. In this study, OPNET is mainly used to verify the results of a mathematical modelling approach using quasi birth-death processes. Authored papers: Remke, A.K.I. and Haverkort, B.R.H.M. and Heijenk, G.J. and Cloth, L. (2008) Bottleneck Analysis for Two-Hop IEEE 802.11e Ad Hoc Networks. In: Analytical and Stochastic Modeling Techniques and Application, 04-06 Jun 2008, Nicosia, Cyprus. pp. 279-294. Lecture Notes in Computer Science 5055. Springer. ISSN 0302-9743 ISBN 978-3-540-68980-5Goering, P.T.H. and Heijenk, G.J. and Haverkort, B.R.H.M. and Haarman, R. (2007) The effect of mobility on local service discovery in the Ahoy ad-hoc network system. In: Proceedings of the European Performance Engineering Workshop, EPEW 2007, 27 - 28 Sept 2007, Berlin, Germany. pp. 284-300. Lecture Notes in Computer Science 4748. Springer Verlag. ISBN 978-3-540-75210-3 Liu, F. and Goering, P.T.H. and Heijenk, G.J. (2007) Modeling service discovery in ad-hoc networks. In: Proceedings of the Fourth ACM International Workshop on Performance Evaluation of Wireless Ad Hoc, Sensor, and Ubiquitous Networks, PE-WASUN 2007, 22 - 26 Oct 2007, Chania, Greece. pp. 9-16. Association for Computing Machinery. ISBN 978-1-59593-808-4 Goering, P.T.H. and Heijenk, G.J. (2006) Service discovery using Bloom filters. In: Proceedings of the twelfth annual conference of the Advanced School for Computing and Imaging, June 14-16, 2006, Lommel, Belgium. pp. 219-227. Advanced School for Computing and Imaging (ASCI). ISBN 90-810849-1-7 OPNET Technologies, Inc. is a leading provider of solutions for managing networks and applications. OPNET's best-in-class solutions address application troubleshooting, application monitoring, network monitoring, network configuration management, capacity management, and network simulation. OPNET’s solutions have been operationally proven in thousands of customer environments worldwide, including corporate and government enterprises, government and defense agencies, network service providers, and network equipment manufacturers. For more information about OPNET and its products, visit www.opnet.com. |
