Using Site-Specific, Ray-Tracing Channel Models to Control Wireless Testbeds

Laboratory-based multi-node wireless testbeds are essential to building and experimenting with mobile wireless networks such as MANETs, DTNs, or custom radios and protocols. Several systems based on many-to-many channel emulators have been built, however these systems rely on either a simple deterministic channel model such as free-space path loss, or a general stochastic channel model, where the only input determining channel characteristics is node distance. In order to more thoroughly test radio and protocol performance in a wider variety of scenarios, it is necessary to incorporate site-specific channel characteristics. We have experimented with using RF ray-tracing software to model site-specific real-world environments at the University of Maryland (UMD) campus. We have used these channel model predictions to drive two different types of channel emulator-based wireless testbeds, and have compared results from those testbeds to field tests in the actual locations. Finally, we have experimented with various levels of detail in our environment models to evaluate the payoff, in terms of realism, for spending extra time and resources to build highly-detailed environmental models.