Models and Methodologies for Realistic Propagation Simulation for Urban Mesh Networks
University of Delaware Newark
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By providing connectivity to mobile users, mesh networks are poised to become a major extension of the Internet. More than 300 cities and towns have plans to deploy mesh networks, and several dozen cities have already deployed these networks. These mesh networks are meant to enhance city and emergency services communication as well as to provide city-wide, low-cost, ubiquitous Internet access for residents and visitors. Such networks promise to bring dramatic changes to data accessibility and hence have a major impact on society. Simulation is the integral step in the validation of mesh networking protocols. However, currently, most simulations use the trivial disk propagation model i.e., the signal propagates exactly R meters and no further or a highly idealized propagation model such as the free-space or the two-ray model. Due to the presence of buildings, propagation in urban environments is far more complicated than the propagation presented by these simple models. Consequently, channel variability, which is a key aspect of wireless networking, is not well modeled in todays simulations. The result is that many insights gained from the simplistic environment do not necessarily hold in the urban environment, casting doubt on the applicability of the conclusions drawn from these simulations. While the reasons that realistic propagation models are typically not included into network simulations is not well documented, it seems that one of the main reasons include the belief that propagation modeling is computationally intractable and that propagation cannot be realistically modeled due to small-scale fading and delay spread. This dissertation focuses on developing models for realistic propagation simulation and the implications of these models on simulation of urban mesh networks. The dissertation also provides measurements and models for time-varying nature of propagation and characterization of the effect of interference on packet success probability.
- Computer Systems