Using FDTD to evaluate ray-tracing models for propagation prediction in urban microcells

In recent years a number of ray-tracing based models have been developed for making site-specific propagation predictions in urban microcells. These models have usually been validated by comparison with path loss and delay spread measurements. Because of the complexity of the environments in which the measurements are made it is often not clear from the comparisons why the predictions are inaccurate in some areas and how the models can be improved. The purpose of this paper is to introduce some simple techniques by which the finite difference time domain (FDTD) method can be used to evaluate the accuracy of ray-tracing based propagation models.