| Discrete-event simulation is among the most commonly used techniques to evaluate protocols and architectures for mobile ad hoc networks. However, detailed simulation of large wireless networks is computationally intensive due to the necessity of simulating the interference among multiple simultaneous transmissions in the radio channel. The first result of this work is establishing necessity of simulating physical layer factors such as signal reception, path loss, fading, interference and noise computation, and preamble length. It is shown that such factors are relevant to the performance evaluations of higher layer protocols. The second part of this work investigates a number of techniques to optimize the performance of such simulations. The specific techniques that have been used include geographic partitioning using the effects of signal propagation on basic simulator performance as well as the parallel optimizations needed to execute the simulation using a synchronous conservative parallel simulation algorithm.{09}The parallel optimizations primarily consist of extracting lookahead necessary for the conservative simulation algorithm from the IEEE 802.11 MAC protocol and radio models. The optimizations were implemented in GloMoSim, a parallel simulator for mobile ad hoc networks, and a set of experiments were performed to measure their impact on the execution time of the simulation. |
