Wireless Propagation in Non Line of Sight Urban Areas using Uniform Theory of Diffraction

Abstract

This paper describes a three-dimensional electromagnetic propagation model for signal power prediction in a non line of sight urban area located in Singapore. The model, which is implemented using the Ohio State NEC-BSC V4.2 basic scattering code and is based on ray theory and uniform theory of diffraction (UTD) takes into account first-order, second order, and third order effects including triple reflections and diffractions. The simplified propagation model of Raffles Place, the central business district of Singapore, uses more than 360 geometrical structures and is compared with data measured at 937.6 MHz along a drive route at the site. The results from the propagation model produced reasonable agreement with the measurements showing that a simplified model using UTD can be used to simulate the gross features of electromagnetic scatter in an urban area. It is shown that use of penetrable dielectric building walls are also necessary for accurate prediction of radio wave propagation in urban areas under non line of sight conditions. It is also found that third order scattering effects can be dominant in non line of sight situations and may be necessary for accurate predictions.