Projekte : AWDS - Wireless Multi-Hop Routing
AWDS - Wireless Multi-Hop Routing
Drahtlose Multihop-Netze erlauben die breitbandige Anbindung von Stadtteilen oder entlegenen Gebieten an das Internet,
erfordern aber meist aufwändige Administration. AWDS ist ein neues Routingverfahren, das unterhalb der IP-Schicht
operiert und die Pfadsuche und Adressvergabe transparent gestaltet. Es ist für den Einsatz in Embedded-Linux-Geräten
optimiert, kann aber auch anderweitig Verwendung finden.
Veröffentlichungen
Experimental Validation of the ns-2 Wireless Model using Simulation, Emulation, and Real Network
Svilen Ivanov, André Herms, and Georg Lukas,
Proceedings of the 4th Workshop on Mobile Ad-Hoc Networks (WMAN'07),
pp. 433 - 444,
Feb. 26. - March 2.,
2007
[abstract]
[BibTeX]
Wireless network research in the last years is often based on simulation.Ns-2 is a widely used wireless network simulation tool for this purpose.However, there are no published results about the accuracy of the ns-2 wireless model in the literature so far. In this paper we present a validation of the wireless model of ns-2 done by comparing the network characteristics of a simulated, an emulated, and a real wireless network. In order to show only the relevant differences, we have calibrated the radio propagation model of ns-2 to the real network and have used the same routing protocol implementation and the same application data traffic in all the compared networks. The results show that the packet delivery ratios, the connectivity graphs,and the packet latencies are represented in the model with an average error of 0.3, 10, and 57 respectively. Based on these results we conclude that the packet delivery ratios, and network topologies are accurately represented in ns-2, once the simulation parameters are properly adjusted. The accuracy of the packet latencies is lower and therefore statements about latencies in the real network based on the simulation results have a lower validity. Based on these results we provide recommendations for future development of the ns-2.
@inproceedings{cite:Ivanov2007,
author = {Svilen Ivanov and Andr\'e Herms and Georg Lukas},
title = {Experimental Validation of the ns-2 Wireless Model using Simulation, Emulation, and Real Network},
booktitle = {Proceedings of the 4th Workshop on Mobile Ad-Hoc Networks (WMAN'07)},
publisher = {VDE Verlag},
year = {2007},
pages = {433 -- 444},
url = {http://ivs.cs.uni-magdeburg.de/EuK/forschung/publikationen/pdf/2007/wman07magdeburg.pdf}
}
Interval based Off-Line Clock Synchronization for Wireless Mesh Networks
Georg Lukas, André Herms, and Daniel Mahrenholz,
Proceedings of the International Symposium on Computer Performance, Modeling, Measurements, and Evaluation,
2007
[abstract]
[BibTeX]
Wireless mesh networks suffer from various problems like congestion or packet collisions. To identify and overcome these problems an exact global view of the communication is required. However, it is not possible to observe the whole network from a single location. Instead, a distributed monitoring is necessary, which has to include clock synchronization. We present a new interval-based algorithm for the off-line synchronization of passively monitored network events. It calculates the worst-case time interval for every event on a global clock, while considering inaccuracies caused by processing jitter and non-uniform clock drifts. The experimental evaluation on a live mesh network shows an accuracy of better than $130�s$ over a four-hop distance, which is below the minimum transmission time of data packets. Thereby, our algorithm creates a highly precise global view of the network, which allows a detailed diagnosis of wireless mesh networks.
@inproceedings{cite:Perf2007,
author = {Georg Lukas AND Andr\'e Herms AND Daniel Mahrenholz},
title = {Interval based Off-Line Clock Synchronization for Wireless Mesh Networks},
booktitle = {Proceedings of the International Symposium on Computer Performance, Modeling, Measurements, and Evaluation},
publisher = {ACM},
year = {2007},
volume = {35}
}
Realism in Design and Evaluation of Wireless Routing Protocols
André Herms, Georg Lukas, and Svilen Ivanov,
Proceedings of First international Workshop on Mobile Services and Personalized Environments (MSPE'06),
Aachen, Germany,
November,
2006
[abstract]
[BibTeX]
In this paper we consider the problem of reliable communication in wireless routing protocols. Many routing protocols for wireless networks use assumptions, that are known to be invalid in this special kind of networks. These shortcomings are not detected in the protocol evaluation, because common simulation tools are also based on these assumptions. In this paper we present a more realistic simulation model and a simple way of enabling existing protocols to handle real conditions of wireless propagation. A proof-of-concept implementation is presented and evaluated using simulation and measurements in a real and emulated network.
@inproceedings{cite:awds06,
author = {Andr\'e Herms and Georg Lukas and Svilen Ivanov},
title = {Realism in Design and Evaluation of Wireless Routing Protocols},
booktitle = {Proceedings of First international Workshop on Mobile Services and Personalized Environments (MSPE'06)},
year = {2006},
url = {http://ivs.cs.uni-magdeburg.de/EuK/forschung/publikationen/pdf/2006/awds-mspe.pdf}
}
Unified Development and Deployment of Network Protocols
André Herms and Daniel Mahrenholz,
Proceedings of Meshnets '05,
Budapest, Hungary,
July,
2005
[abstract]
[BibTeX]
In this paper we describe GEA- an interface that enables the development of event-driven network protocols, their testing in a simulated network and deployment using a single, unmodified code. Normally testing and deployment requires separated implementations which results in a significant development and maintenance overhead. This is due to the different APIs of the underlying systems. As a solution to this problem we propose a common, generic event based interface called GEA. We present its design principles and show by example how to implement a network protocols with it. Finally we compare the execution of the protocol implementation in both environments to show the effectiveness of our approach.
@inproceedings{cite:Herms2005,
author = {Andr\'e Herms and Daniel Mahrenholz},
title = {Unified Development and Deployment of Network Protocols},
booktitle = {Proceedings of Meshnets '05},
year = {2005},
url = {http://www-ivs.cs.uni-magdeburg.de/EuK/forschung/publikationen/pdf/2005/gea.pdf}
}
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