Toward Ubiquitous Real-Time Radio Propagation Modeling: The Exploitation of Cyber Resources, GPU and Fast and Accurate EM Algorithms

Radio propagation modeling and prediction play an important role in the understanding of electromagnetic (EM) wave propagation in complex environments, as well as in the design of wireless communications and radar systems

Use of a Realistic Ray-Based Model for the Evaluation of Indoor RF Coverage Solutions Using Reconfigurable Intelligent Surfaces

A previously developed Huygens-based, “antenna-array-like” macroscopic model for scattering from metasurfaces is embedded into a ray-tracing tool and used to carry out realistic RF-coverage evaluations in indoor environment. Using the reciprocity of the link, we extend prediction to multiple-bounce paths that include metasurface scattering at the beginning or at the end of the interaction chain. The proposed model allows us to carry out coverage evaluations for any realistic RIS design by modifying a few simple parameters. In this work, reference environments such as T–shaped and L–shaped corridor cases are considered with different deployment solutions of anomalous and focusing reflectors. The results show that a gain of about 15–20 dB can be obtained in blind-spot locations with proper RIS placement and configuration, without the use of any additional active radio head, even when using simple designs such as pre-configured lossy phase-gradient metasurfaces

A Reciprocal Heuristic Model for Diffuse Scattering from Walls and Surfaces

Diffuse scattering of electromagnetic waves from natural and artificial surfaces has been extensively studied in various disciplines, including radio wave propagation, and several diffuse scattering models based on different approaches have been proposed over the years, two of the most popular ones being Kirchhoff Theory and the so-called Effective Roughness heuristic model. The latter, although less rigorous than the former, is more flexible and applicable to a wider range of real-world cases, including non-Gaussian surfaces, surfaces with electrically small correlation lengths and scattering from material inhomogeneities that are often present under the surface. Unfortunately, the Effective Roughness model, with the exception of its Lambertian version, does not satisfy reciprocity, which is an important physical-soundness requirement for any propagation model. In the present work, without compromising its effectiveness and its simple and yet sound power-balance approach, we propose a reciprocal version of the Effective Roughness model, which can be easily implemented and replaced to the old version in ray-based propagation models. The new model is analyzed and compared to the old one and to other popular models. Once properly calibrated, it is shown to yield similar - if not better - performance with respect to the old one when checked vs. measurements

A Simple and Versatile Field Prediction Model for Indoor and Indoor-to-Outdoor Propagation

A simple field prediction model based on a combination of a two-parameter propagation formula and a multi-wall model is proposed for fast and yet accurate indoor and indoor-to-outdoor field prediction. The model's approach is based on: 1) simplicity; 2) physical soundness; and 3) adaptability to the available environment-database format. The model is validated versus both ray tracing and measurements in different environments and it is shown to perform very well in all cases. Moreover, the model is very fast and can exploit the accuracy plus of deterministic prediction based on the 3-D indoor building map whenever it is available

A Method for the Electromagnetic Characterization of Construction Materials Based on Fabry–Pérot Resonance

The determination of the complex permittivity of low-loss construction materials at frequency bands above 6 GHz that are being proposed to allocate forthcoming mobile radio services is of critical importance for the design and deployment of future wireless systems. In this paper, a simple free-space method for the electromagnetic characterization of construction materials that does not require multiple reflection or transmission coefficient measurements for different incidence angles or complex optimization procedures is proposed and tested. The method is shown to yield permittivity and conductivity values in agreement with the literature for some common-use materials using a relatively simple measurement setup and procedure

Ultra-wide bandwidth systems for the surveillance of railway crossing Areas

Level crossings are critical elements of railway networks where a large number of accidents take place every year. With the recent enforcement of new and higher safety standards for railway transportation systems, dedicated and reliable technologies for level crossing surveillance must be introduced in order to comply with the safety requirements. In this survey the worldwide problem of level crossing surveillance is addressed, with particular attention to the recent European safety regulations. In this context, the capability of detecting, localizing, and discriminating the vehicle/obstacle that might be entrapped in a level crossing area is considered of paramount importance to save lives, and at the same time avoid costly false alarms. In this article the main solutions available today are illustrated and their pros and cons discussed. In particular, the recent ultra-wide bandwidth technology, combined with proper signal processing and backhauling over the already deployed optical fiber backbone, is shown to represent a promising solution for safety improvement in level crossings

A Study on mm-Wave Propagation In and Around Buildings

mm-waves are envisaged as a key enabler for 5G and 6G wireless communications, thanks to the wide bandwidth and to the possibility of implementing large-scale antenna arrays and advanced transmission techniques, such as massive MIMO and beamforming, that can take advantage of the multidimensional properties of the wireless channel. In order to analyze in depth the peculiar characteristics of mm-wave propagation, joint measurement and simulation campaigns in indoor and outdoor microcellular environments have been carried out. The investigation highlights that the assumption that mm-wave NLoS connectivity is hardly feasible is not necessarily true as significant reflections, scattering and even transmission mechanisms can provide good NLoS coverage in the considered indoor and outdoor scenarios. This is also reflected in the limited angle-spread differences between LoS and NLoS locations in some cases. Finally, the contribution of different propagation mechanisms (reflection, diffraction, scattering and combination of them) to the received signal is analyzed in the paper with the help of ray tracing simulations. These outcomes can be helpful to predict the performance of mm-wave wireless systems and for the development of deterministic and geometric-stochastic mm-wave channel models

Characterizing the UAV-to-Machine UWB Radio Channel in Smart Factories

In this work, the results of Ultra-Wideband air-to-ground measurements carried out in a real-world factory environment are presented and discussed. With intelligent industrial deployments in mind, we envision a scenario where the Unmanned Aerial Vehicle can be used as a supplementary tool for factory operation, optimization and control. Measurements address narrow band and wide band characterization of the wireless radio channel, and can be used for link budget calculation, interference studies and time dispersion assessment in real factories, without the usual limitation for both radio terminals to be close to ground. The measurements are performed at different locations and different heights over the 3.1-5.3 GHz band. Some fundamental propagation parameters values are determined vs. distance, height and propagation conditions. The measurements are complemented with, and compared to, conventional ground-to-ground measurements with the same setup. The conducted measurement campaign gives an insight for realizing wireless applications in smart connected factories, including UAV-assisted applications

Item level characterization of mm-wave indoor propagation

According to the current prospect of allocating next generation wireless systems in the underutilized millimeter frequency bands, a thorough characterization of mm-wave propagation represents a pressing necessity. In this work, an “item level” characterization of radiowave propagation at 70 GHz is carried out. The scattering properties of several, different objects commonly present in indoor environment are investigated by means of measurements carried out in an anechoic chamber. The measured data have been also exploited to tune some parameters of a 3D ray tracing model