in this paper, a new propagation model based on utd for multiple diffraction paths in cellular mobile radio communications in urban environments is proposed. moreover, the most rigorous novel utd-based expressions for multiple diffractions by buildings and excess path losses are d - rived and analyzed. for this purpose, building rows are supposed to have rectangular cross-sections with the same...

Designers of low-power radio systems for use in urban areas would benefit from accurate computer-based predictions of signal loss due to shadowing. This paper presents a propagation prediction method that exploits a building database and considers the three-dimensional profile of the radio path. Models and algorithms are provided that allow the application of Fresnel-Kirchhoff diffraction theor...

Ray tracing algorithms rely on two dimensional or three dimensional database. They use ray optical techniques referred to as the uniform theory of diffraction (UTD) using building database given as polygons. Building geometries can also be modelled as having non-planar geometries, and this would be important in modeling of shadowing loss due to curved structures in urban radio propagation. To d...

An efficient algorithm that dynamically calculates all possible ray paths in outdoor (macroand micro-cells and land mobile satellite, LMS) and indoor environments is presented in this paper. The algorithm is based on the sweep line technique. Additionally a quadtree (bounding box [1]) division of the study environment is used to reduce search time. For indoor and microcellular environments wall...

The analysis and simulation of electromagnetic (EM) wave propagation represent a crucial task in planning cellular networks for mobile communication. When an adequate building database is available, deterministic 3D ray tracing techniques are quite useful and accurate to face this problem, but since their computational complexity is time consuming, a preprocessing step is necessary. Such a step...

In this paper, detailed numerical simulations of sound propagation in an urban environment are presented. The focus is on propagation from a “source canyon” to a distant “receiver canyon”. Such numerical simulations have to take into account multiple reflections, both specular and diffuse, multiple diffractions, the presence of different building materials, and also the interaction with a movin...

A ray tracing based cellular coverage simulator has been parallelized in order to speed up excecution. The simulator has been developed for accurate prediction of radio wave propagation in urban microcells. It combines a vertical plane model simulating the wave propagation over the buildings and a horizontal plane model simulating the wave propagation in the street canyons between the buildings...

The radar cross-section patterns of lossy dihedral corner reflectors are calculated using a uniform geometrical theory of diffraction for impedance surfaces. All terms of up to third order reflections and diffractions are considered for patterns in the principal plane. The surface waves are included whenever they exist for reactive surface impedances. The dihedral corner reflectors examined hav...

The effects of anomalous dispersion (resonance) on multiple reflection of x rays and their interference in crystals at atomic absorption edges are studied. Intensity ratios of two inversion-symmetry-related multiple diffractions at or near absorption edges exhibit highly phase-sensitive profiles with strong asymmetric characteristics, unlike those far from the edges. A new resonance perturbatio...