Urban radiowave propagation modelling: a 3-D wave analysis

Understanding the diffraction undergone by radiowaves propagating around 3-dimensional obstacles is essential in modelling the mobile radio channel in built-up areas. With the development of 3-dimensional building databases for cities the deterministic models are expected to become increasingly useful. For the propagation of radiowaves at typical mobile radio frequencies, the simplest representations for the building structures are knife-edges and plateaux. Most of the propagation models presented in past literature have been restricted to the two-dimensional problem, in which the great circle path constructed between the transmitter and receiver has been assumed to be the only propagation path. In these studies, the transverse variations of the obstacles have not been taken into consideration. A three-dimensional model is adopted in an attempt to produce a more realistic prediction in the practical scenario. The mathematical model used is based on the asymptotic path integral technique. The attenuation functions for paraxial radiowave propagation over a cascaded arrangement of finite-width knife-edges and plateaux can be derived by employing Huygens' principle and the propagator, or Green's function, over a linear, inclined ground plane segment.