A New Trend in Propagation Prediction

Abstract

Owing to its direct applicability in solving problems of the telecommunications industry, propagation prediction for a long time has been an important area of research and development. Because of the increasing complexity of wireless networks, growing number of smaller cells, and higher intercell interference, software tools that aid in network optimization are necessary. There fore, in the study of particular environments, where wireless networks are deployed, deterministic propagation models play an important role. Deterministic models can predict the path loss in a given scenario through the simulation of the main propagation phenomena such as reflections and diffractions. The most commonly used deterministic solutions for radio coverage prediction are ray models, which model electromagnetic (EM) waves through optical laws. However, since their appearance nearly 40 years ago, there has been an increasing interest in using other techniques such as finite-difference EM methods. These methods [the most well known is finite-difference time-domain (FDTD) method] solve Maxwell's equations on a discrete space time grid. They can provide highly accurate results, provided there are accurate boundary conditions, since the reflections, diffractions, and scattering effects are implicit. This contrasts with ray-based methods that must account explicitly for a limited number of rays. This also explains why Yee's FDTD methods, have been and are still widely used today, especially in confined environments such as for antenna design that involves reasonable grid sizes.