Simulating wireless networks accurately is a non-trivial task because of the large
parameter space that affects the performance of such networks. Increasing the amount of
detail in the simulation model increases these requirements by many times. Hence there
is a need to develop suitable abstractions that maintain the accuracy of the simulation
while keeping the computational resource requirements low. The topic of wireless network
simulation models is explored in this research, concentrating on the medium access control
and the physical layers.
In the recent years, a large amount of research has focussed on various kinds of wireless
networks to fit various application domains. Mobile Ad-Hoc Networks (MANETs), Wire-
less Local Area Networks (WLANs), and Sensor Networks are a few examples.The IEEE
802.11 Physical layer(PHY) and Medium Access Control (MAC) layer are the most popular
wireless technologies in practice. Consequently, most implementations use the IEEE 802.11
specifications as the basis for higher layer protocol design and analyses.
In this dissertation, we explore the correctness, efficiency, and realism of wireless network
simulations. We concentrate on the 802.11-based wireless network simulations, although the
methods and results can also be used for various other wireless network simulations too.
While many simulators model the IEEE 802.11 wireless networks, almost all of them tend to
make some abstractions to lessen the computation burden and to obtain reasonable results.
A comparitive study of three wireless simulators is made with respect to the correctness of
their ideal behavior as well as their behavior under a high degree of load.
Further, the physical-layer abstraction in wireless network simulations tends to be very
simplistic because of the huge computational requirements that are needed to accurately
model the various propagation, fading, and shadowing models. When mobility is taken into
account several other issues like the Doppler effect should also be accounted for.
This dissertation explores an empirical way to model the physical layer which cumula-
tively accounts for all these effects. From a network protocol designers perspective, it is
the cumulative effect of all these parameters that is of interest.
Our major contribution has been the investigation of novel empirical models of the
wireless physical layer, which account for node mobility and other effects in an outdoor
environment. These models are relatively more realistic and efficient when implemented
in a simulation environment. Our simulation experiments validate the models and pro-
vide simulation results which closely match our outdoor experiments. Another significant
contribution is in understanding and design of wireless network simulation models.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/14558 |
| Date | 10 January 2007 |
| Creators | Subbareddy, Dheeraj Reddy |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Detected Language | English |
| Type | Dissertation |
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