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This master thesis deals with the evaluation and comparison of different network simulation tools. Choosing an appropriate simulator can be very hard, as a lot of tools are available and the familiarisation with a simulator is very time-consuming. So usually a researcher selects one tool and then uses it for all his/her research studies. This thesis assists with that decision by comparing three leading simulators—ns-2, OMNeT++, and QualNet—with a real-world testbed.
At the beginning of this thesis, the state-of-the-art in wired and wireless network simulations is described and the most important findings are summarised. The main aspect of the thesis is the analysis of the quality of the different simulators. The approach used for the rating of their accuracy is to define different scenarios and implement them as accurately and similarly as possible in all three tools. On the basis of several metrics, the results of the simulation are compared to the measuring in a testbed. Beside the accuracy of the different simulators/models, also some additional aspects are drawn on in comparison, such as the ease of use and the extensibility and scope of operations of the tools.
Concerning the accuracy, it was found out that no simulator is superior to its competitors. Instead it highly depends on the actual simulation scenario. QualNet's models are identified as more complex than those of ns-2. Therefore they sometimes provide a more detailed simulation and allow a deeper analysis of the network's originalities. Ns-2's models on the other hand provide very good approximations of the `overall process' and come closer to reality regarding the final values. OMNeT++ is not recommended in this thesis because certain features are still missing.
As ns-2 and QualNet performed almost coequal as far as the accuracy is concerned, for the decision which tool to use, aspects should be drawn on that are independent from the accuracy. An advantage of QualNet is the graphical user interface that animates simulation runs in a very enlightening way. Ns-2 on the other hand is free of charge and predestined to be extended with new features such as a newly developed protocol.
| Scenario Wireless Simple Access Point | ||
The office hallway for the indoor experiment
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The footpath (looking north-east) for the outdoor experiment,
Google Earth it
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The footpath (looking south-west) for the outdoor experiment,
Google Earth it
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| Scenario Wireless Propagation Models | ||
Open field next to the river Sieg (looking east),
Google Earth it
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Open field next to the river Sieg (looking west),
Google Earth it
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| Screenshots | ||
Screenshot from QualNet. Blue circles indicate WLAN signals,
green arrows indicate packet transmissions.
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Screenshot from nam, a visualisation tool for ns-2. The circles indicate
broadcast messages, the blue rectangle indicates a packet transmission.
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Screenshot from OMNeT++ and the INET Framework. Next to the main window
(bottom left), some modules are shown in detail, e.g. for host[1] and
networkLayer of host[1] (right).
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| © 2008 Karsten Reineck | Impressum |