Topics on modelling and simulation of wireless networking protocols

The use of computer simulation to study complex systems has grown significantly over the past several decades. This is especially true with regard to computer networks, where simulation has become a widespread tool used in academic, commercial and military applications. Computer model representations of communication protocol stacks are used to replicate and predict the behavior of real world counterparts to solve a variety of problems.The performance of simulators, measured in both accuracy of results and run time, is a constant concern to simulation users. The running time for high delity simulation of large-scale mobile ad hoc networks can be prohibitively high. The execution time of propagation e ects calculations for a single transmission alone can grow unmanageable to account for all potential receivers. Discrete event simulators can also su er from excessive generation and processing of events, both due to network size and model complexity. In this thesis, three levels of abstracting the Institute of Electrical and Electronics Engineers (IEEE) 802.11 Request to Send/Clear to Send (RTS/CTS) channel access mechanism are presented. In the process of assessing the abstractions' ability to mitigate runtimecost while retaining comparable results to that of a commercially available simulator, OPNET, the abstractions were found to be better suited to collecting one metric over another.Performance issues aside, simulation is an ideal choice for use in prototyping and developing protocols. The costs of simulation are orders of magnitude smaller than that of network testbeds, especially after factoring in the logistics, maintenance, and space required to test live networks. For instance, Internet Protocol version 6 (IPv6) stateless address autocon guration protocols have yet to be convincingly shown to cope with the dynamic, infrastructure-free environment of Mobile Ad hoc Networks (MANETs). This thesis provides a literature survey of autocon guration schemes designed for MANETs, with particular focus on a stateless autocon guration scheme by Jelger andNoel (SECON 2005). The selected scheme provides globally routable IPv6 pre xes to a MANET attached to the Internet via gateways. Using OPNET simulation, the Jelger-Noel scheme is examined with new cluster mobility models, added gateway mobility, and varied network sizes. Performance of the Jelger-Noel scheme, derived from overhead, autocon gura ion time and pre x stability metrics, was found to be highly dependent on network density, and suggested further re nement before deployment.Finally, in cases where a network testbed is used to test protocols, it is still advantageous to run simulations in parallel. While testbeds can help expose design aws due to code or hardware di erences, discrete event simulation environments can o er extensive debugging capabilities andevent control. The two tools provide independent methods of validating the performance of protocols, as well as providing useful feedback on correct protocol implementation and con guration. This thesis presents the Open Shortest Path First (OSPF) routing protocol and its MANET extensions as candidate protocols to test in simulated and emulated MANETs. The measured OSPF overhead from both environments was used as a benchmark to construct equivalent MANET representations and protocol con guration, made particularly challenging due to the wired nature of the emulation testbed. While attempting to duplicate and validate results of a previous OSPF study, limitations of the simulated implementation of OSPF were revealed.M.S., Electrical Engineering -- Drexel University, 200