Plane-Wave UTD-PO Formulations for Multiple-Diffraction by Trees and Buildings at Millimeter-Wave Frequencies

Two uniform theories of diffraction or physical optics (UTD-PO) formulations for the analysis of the multiple-diffraction of millimeter plane waves which is caused by both trees and buildings, in vegetated residential areas, are hereby presented. The two solutions consider the buildings, modeled as knife-edges and rectangular sections (a more complex and realistic shape), respectively, and the influence of the tree canopies-assumed to be higher than the average rooftop height-is taken into account by considering the proper attenuation factors and phasors into the building diffraction phenomenon. The formulations have been validated through comparison with solutions previously published by other authors, and the main advantage of the proposed models is that, thanks to their recursion, only single diffractions are involved in the calculations. This way, the need of higher order diffraction terms in the diffraction coefficients is avoided, thereby lowering the computational effort. The results, focused on the 5G millimeter-wave (mmWave) candidate bands, can be applied in the planning of forthcoming mobile communication systems.