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Deterministic field prediction has been widely used to provide channel data for coverage analysis. Among these prediction tools, point cloud-based methods have been developed for millimeter-wave frequencies in order to characterize the environment with higher precision, but they have not taken into account all the necessary propagation mechanisms. In this paper, we present the implementation for predicting both specular reflections and diffraction as well as the total channel, including the aforementioned mechanisms along with scattering and shadowing. Both line-of-sight (LOS) and non-LOS channels are predicted and validated against measurements in a cafeteria. The result shows excellent agreement between prediction and measurement in terms of power delay profiles, power angular spectra, path loss, mean delay, delay spread, and azimuth spread. [ABSTRACT FROM PUBLISHER]

In this work, we study the impact of antenna radiation patterns disturbed by urban furniture on propagation characteristics. The propagation in urban scenario is modeled with a ray-based deterministic tool. Different base station scenarios are discussed: antenna in proximity of a wall; antenna mounted on a lamp post; and antenna on a bus stop shelter. The statistical influence of the support is evaluated comparing the results in terms of pathloss with the ones obtained when the isolated antenna radiation patterns are considered. [ABSTRACT FROM PUBLISHER]

In this paper, we derive the backscattering coefficient/forward propagation equation for frequency-modulated waves of high-frequency radar over the sea. Numerical simulations have been performed in order to compare the characteristics of a constant frequency and frequency-modulated electromagnetic wave in the function of sea state and index profile. From these simulations, we have drawn some conclusion on the differences in the Doppler spectrum observed for the two waveforms. [ABSTRACT FROM PUBLISHER]

A novel deterministic approach to model the radio wave propagation channels in complex indoor environments reducing computational complexity is proposed. This technique combines a neural network and a 3-D ray launching algorithm in order to compute wireless channel performance in indoor scenarios. An example of applying the method for studying indoor radio wave propagation is presented and the results are compared with a very high resolution fully 3-D ray launching simulation as the reference solution. The new method allows the use of a lower number of launched rays in the simulation scenario whereas intermediate points can be predicted using neural network. Therefore a high gain in terms of computational efficiency (approximately 80% saving in simulation time) is achieved. [ABSTRACT FROM PUBLISHER]

The theory of propagating waves near a surface is reviewed with an eye to gain insight into the mechanisms involved, and to provide analytical-based models, for power-efficient on-body propagation. The Zenneck wave, and in particular the Norton wave, are appraised as candidate mechanisms for the propagation. For flush-mounted ("band aid") antennas, desired for on-body sensors, the Norton wave is the only direct propagation mechanism between the sensors. The Norton wave fits very well to simulation results presented here, and comparisons are also made with available published physical experiments, although these measurements typically feature the optical paths of elevated, or non-flush, antennas. [ABSTRACT FROM AUTHOR]

We examine two spurious numerical artifacts of the complex envelope (CE) alternating-direction-implicitfinite-difference time-domain (ADI-FDTD) method, viz, spurious charges and anomalous wave propagation (modes with positive phase velocity and negative group velocity). These artifacts are also present in the conventional ADI-FDTD; however, the spurious charges in CE-ADI-FDTD have a fundamental distinction from those of ADI-FDTD: they are static in ADI-FDTD and implicitly time-harmonic in CE-ADI-FDTD. Spurious charges are particularly detrimental to CE-ADI-FDTD simulations because they produce secondary radiation. We also show that spurious charges can be reduced by a fixed-point iterative correction in CE-ADI-FDTD. [ABSTRACT FROM AUTHOR]

A model is presented that extends the applicability of the propagation data collected during a long measurements campaign in a particular site and for a particular radiolink, to a generic link in a generic site. In fact, the objective of the model is to create a set of attenuation time series to be used in the design of advanced TLC systems. The model assumes that the marked differences of the rain statistics observed in various locations are, in first approximation, mainly due to the different frequency of occurrence of the various rainy events rather than to their shape. Starting from this assumption the model selects, from a large database of rain attenuation events collected in a particular site, a subset that, after an appropriate frequency and elevation scaling, can be used to represent time series of attenuation recorded in other experimental conditions (as for both site and link). The model has been applied to the attenuation data collected at Spino d'Adda (Milan, Italy) during the ITALSAT propagation campaign in order to simulate attenuation time series in several different links and sites. The model demonstrated good performance both in link conditions and climates, similar and different from the Spino d'Adda ones. [ABSTRACT FROM AUTHOR]

This paper presents a ray-tube tracing method to simulate waves propagating in curved road tunnels from base stations for mobile communications. Ray tubes are traced by including multiple reflections in the curved tunnels and diffractions from wedges of the tunnel structures, together with the direct path. To verify this ray-tube tracing approach, field measurements of 900 MHz signals in two curved road tunnels from GSM base stations were performed for comparisons with the ray-tube tracing simulations. By tracing ray tubes reflected and diffracted from the curved structures of the tunnels, the effects of the curvature on wave propagations in large guiding structures can be evaluated. Good agreement between simulations and measurements has been obtained. A parametric study of the influence of the tunnel geometry and the signal frequency on the path loss is also presented by applying this ray-tube tracing method. Curved tunnels for different radii of curvature in the tunnel cross-section and horizontal plane and also lengths of the curved part are compared, together with rectangular tunnels. Simulations of the field distribution over the cross-section of the curved tunnel away from the transmitting antenna are demonstrated as well. The ray-tube tracing program can be applied to determine the deployment of the base-station antennas for improving signal coverage in tunnels, which may have curved structures. [ABSTRACT FROM AUTHOR]

Deals with the use of a time-domain (TD) analysis for the prediction of radio wave propagation for wireless communications in urban environments. Comparison between measured propagation data and predictions given by a polygonal line (PL) simulator; Purpose of the TD analysis; Appraisal of predictions obtained with the PL simulator.

Proposes a ray-tracing approach for indoor and outdoor radio wave propagation through window structures. Results of the finite-difference time-domain method for the propagation; Description of a ray-tracing algorithm; Characteristics of a ray-optics window model.

Presents a ray-tracing procedure based on a triangular grid approach for predicting the propagation of radio waves in urban environments. Facts on the two-dimensional triangulation of propagation environments; Description of a ray-tracing algorithm; Comparison of simulations for radio wave propagation.

Considers scaled models of two-dimensional urban environments in order to investigate radio wave propagation along a vertical plane. Description of a polygonal line simulator; Comparisons on ray-tracing propagation simulation; Types of polygonal shapes examined to test the performance of the polygonal line simulator.

Examines the influence of a diffraction coefficient and building corner shape on predicting the propagation of radio waves in urban environments. Formulation of the diffraction coefficient; Information on a vertical plane launch ray tracing algorithm used in predicting the propagation; Description of a wide-band measurement system.

Presents a study which examined wet antenna attenuation during rain events. Methodology; Measured wet antenna characteristics; Path-attenuation statistics.

Presents a channel parameter simulation for wave propagation in a forest environment. Overview of the forest model; Details on the problems; Fast-field calculations based on reciprocity; Near-field calculation.

Describes a laboratory model designed to investigate radio wave propagation in the perturbed environment of the earth-ionosphere waveguide. Properties of Maxwell's equations involved in the construction of the model; Overview on the problem; Electromagnetic models; Conclusions.