In this work, we continue the analysis of a probabilistic approach and the corresponding stochastic multi-parametric model of wave propagation in built-up areas with randomly distributed buildings. We Concentrate on the influence of buildings' overlay profiles on signal spatial decay, and on path-loss dependence in the frequency domain within UHFIX-band urban propagation channels. Using different buildings' overlay profiles, the field-intensity attenuation along radio paths is examined, taking into account single-scattering and multiple-scattering phenomena, and diffraction from buildings' corners and rooftops, for various positions of receiver and transmitter antennas with respect to surrounding obstacles. The comparison between experimental and theoretical predictions was motivated by the proposed stochastic multi-parametric model and the experimental data obtained for actual areas in Jerusalem (Israel) and Lisbon (Portugal), as well as by other models of multiple diffraction. The discussion is presented for realistic elevations of both terminal antennas to assess the accuracy and limits of the proposed stochastic model. A sensitivity analysis of the influence on the path loss of built-up terrain parameters and the elevation of antennas relative to the buildings surrounding them is presented.
In this work a theoretical and experimental investigation analyzing VHF/ UHF radio wave propagation in a suburban environment with a grid-type street plan is presented for the purpose of personal communication services prediction. A waveguide with randomly distributed gaps (slits) between the sides of buildings is considered as a model of straight streets with two-and three-story buildings. The average field intensity and path loss at the street level, taking into account the reflection from the ground, multireflection, and diffraction from the walls and building edges, are investigated in line-of-sight (LOS) conditions using a new three-dimensional multislit waveguide model. This model gives good agreement with the two-rays model and with an experimentally found law of field intensity attenuation at the street level with high and low building density up to 1-2 km from the source. cumstances there are wide shadow zones with sharp transitions to the illuminated zones. In both zones the multireflection propagation creates an interference picture. In general, the main influence on the field formed in regions with dense buildings is defined by the type of area planning [Walfisch and Bertoni, 1988]. This process of radio wave propa-313
A unified three-dimension probabilistic model is presented to describe multipath phenomena in various built-up areas with randomly distributed buildings placed on rough terrain. The joint information regarding angle-of-arrival and time delay spread is obtained through study of the main propagation mechanisms in urban wireless communication channels. Comparison with other models and with measurements carried out in different urban environments is presented. It is shown that in dense urban areas the distribution of the obstructions surrounding the base station and the moving vehicle, as well as the elevations of both antennas contribute to the signal power profiles in the space and time domains. Using a combination of the statistical description of the built-up terrain and the 3D deterministic approach based on Kirchhoff approximation, the effects of scattering and diffraction phenomena on signal power spatial and temporal distribution are examined.
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