Publications

CONCRETE: A benchmarking framework to CONtrol and Classify REpeatable Testbed Experiments

Authors: Stratos Keranidis, Wei Liu, Michael Mehari, Pieter Becue, Stefan Bouckaert, Ingrid Moerman, Thanasis Korakis, Iordanis Koutsopoulos and Leandros Tassiulas

Conference: FIRE Engineering Workshop 2012, Gent, Belgium, November 2012

Abstract: The global research community has been recently directed towards implementation approaches and evaluation through experimentation in network- ing testbeds. A unique problem that arises during experimentation in such envi- ronments is that several di erent factors may impact the monitored performance of networks under consideration. More speci cally, the major factor that signif- icantly impacts performance is the e ect of interference that is generated either from testbed nodes that simultaneously transmit or from collocated commercial devices belonging to external networks. Moreover, as the level of interference signi cantly varies over time, the monitored performance may present high vari- ation among several executions of the same experiment. In order to ensure stable experimental conditions, speci c tools have to be developed that would be able to detect whether the gathered results have been a ected by external factors. In this work, we present a novel benchmarking framework, developed within the collaboration of CREW and OpenLab EU FP7 projects. The developed frame- work provides for proper evaluation of experimentally gathered results and thus enables the experimenter to arrive at solid conclusions regarding the validity of the conducted experiments.

Download paper: Keranidis_CONCRETE_FIRE_2012_paper.pdf

 

Novel Metrics and Experimentation Insights for Dynamic Frequency Selection in Wireless LANs

Authors: Giannis Kazdaridis, Stratos Keranidis, Adamantios Fiamegkos, Thanasis Korakis, Iordanis Koutsopoulos and Leandros Tassiulas

Conference: WiNTECH - MobiCom 2011, Las Vegas, Nevada, USA, September 2011

The rapidly increasing popularity of IEEE 802.11 WLANs has led the unlicensed frequency bands to unprecedented levels of congestion, especially in densely populated urban areas. Performance experienced by end-users, in such deployments, is significantly degraded due to contention and interference among adjacent cells. In this paper, we develop novel metrics and insights that we use for dynamic frequency selection, incorporating the various features that affect total network interference. The proposed scheme features a novel client feedback mechanism, which enables the nodes of the cell, as well as nodes belonging to different cells, to contribute to interference measurements. Furthermore, we incorporate a traffic monitoring scheme that makes the system aware of prevailing traffic conditions. We design a distributed protocol, through which messages containing the information above are passed by the stations to the access points, where the frequency selection is performed in a dynamic form. The proposed algorithm is implemented using the MADWiFi open source driver and is validated through extensive testbed experiments in both an indoor RF-Isolated environment, as well as in a rich interference, large-scale wireless testbed. Results obtained under a wide range of settings, indicate that our algorithm improves total network throughput, up to a factor of 7.5, compared to static approaches followed by wireless vendors.

Download paper: DFS_WinTECH_2011_paper.pdf

Optimization driven Multi-Hop Network Design and Experimentation: The Approach of the FP7 Project OPNEX

Authors: Kostas Choumas, Stratos Keranidis, Thanasis Korakis, Iordanis Koutsopoulos, Leandros Tassiulas, Felix Juraschek, Mesut Günes, Emmanuel Baccelli, Paweł Misiorek, Andrzej Szwabe, Theodoros Salonidis and Henrik Lundgren

Journal: IEEE Communications Magazine, Radio Communication Series, June 2012

Abstract: The OPNEX project exemplifies system and optimization theory as the foundations for algorithms that provably maximize capacity of wireless networks. The algorithms termed in abstract network models have been converted to protocols and architectures practically applicable to wireless systems. A validation methodology through experimental protocol evaluation in real network testbeds has been proposed and used. OPNEX uses recent advances in system theoretic network control, including the Back-Pressure principle, max-weight scheduling, utility optimization, congestion control, and the primal-dual method for extracting network algorithms. These approaches exhibited vast potential for achieving high capacity and full exploitation of resources in abstract network models and found their way to reality in high performance architectures developed as a result of the research conducted within OPNEX.

Download paper: kohoumas_commag_2012_opnex_journal.pdf

Experimentation in Heterogeneous European Testbeds through the Onelab Facility: The case of PlanetLab federation with the wireless NITOS Testbed

Authors: Stratos Keranidis, Dimitris Giatsios, Thanasis Korakis, Iordanis Koutsopoulos, Leandros Tassiulas, Thierry Rakotoarivelo and Thierry Parmentelat

Conference: TridentCom 2012,Thessaloniki, Greece, June 2012

The constantly increasing diversity of the infrastructure that is used to deliver Internet services to the end user, has created a demand for experimental network facilities featuring heterogeneous resources. Therefore, federation of existing network testbeds has been identified as a key goal in the experimental testbeds community, leading to a re- cent activity burst in this research field. In this paper, we present a federation scheme that was built during the Onelab 2 EU project. This scheme federates the NITOS wireless testbed with the wired PlanetLab Europe testbed, allowing researchers to access and use heterogeneous experimental facilities under an integrated environment. The usefulness of the resulting federated facility is demonstrated through the testing of an implemented end-to-end delay aware association scheme proposed for Wireless Mesh Networks. We present extensive experiments under both wired congestion and wireless channel contention conditions that demonstrate the effectiveness of the proposed approach in a realistic environment. Both the architectural building blocks that enable the federation of the testbeds and the execution of the experiment on combined resources, as well as the important insights obtained from the experimental results are described and analyzed, pointing out the importance of integrated experimental facilities for the design and development of the Future Internet.

Download paper: Keranidis_Federation_TridentCom_2012_paper.pdf

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