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

Methodologies for Future Vehicular Digital Twins

The role of wireless communications in various domains of intelligent transportation systems is significant; it is evident that dependable message exchange between nodes (cars, bikes, pedestrians, infrastructure, etc.) has to be guaranteed to fulfill the stringent requirements for future transportation systems. A precise site-specific digital twin is seen as a key enabler for the cost-effective development and validation of future vehicular communication systems. Furthermore, achieving a realistic digital twin for dependable wireless communications requires accurate measurement, modeling, and emulation of wireless communication channels. However, contemporary approaches in these domains are not efficient enough to satisfy the foreseen needs. In this position paper, we overview the current solutions, indicate their limitations, and discuss the most prospective paths for future investigation.Comment: Submitted to IEEE Intelligent Transportation Systems Magazin

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

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

Ray-tracing-based mm-wave beamforming assessment

The use of large-size antenna arrays to implement pencil-beam forming techniques is becoming a key asset to cope with the very high throughput density requirements and high path-loss of future millimeter-wave (mm-wave) gigabit-wireless applications. Suboptimal beamforming (BF) strategies based on search over discrete set of beams (steering vectors) are proposed and implemented in present standards and applications. The potential of fully adaptive advanced BF strategies that will become possible in the future, thanks to the availability of accurate localization and powerful distributed computing, is evaluated in this paper through system simulation. After validation and calibration against mm-wave directional indoor channel measurements, a 3-D ray tracing model is used as a propagation-prediction engine to evaluate performance in a number of simple, reference cases. Ray tracing itself, however, is proposed and evaluated as a real-time prediction tool to assist future BF techniques

Wireless Communications and Mobile Computing

Presenting comprehensive coverage of this fast moving field, Wireless Communications and Mobile Computing provides the R&D communities working in academia and the telecommunications and networking industries with a forum for sharing research and ideas. The convergence of wireless communications and mobile computing is bringing together two areas of immense growth and innovation. This is reflected throughout the journal by strongly focusing on new trends, developments, emerging technologies and new industrial standards. Wireless Communications and Mobile Computing is archived in Portico, which provides permanent archiving for electronic scholarly journals, as well as via the LOCKSS initiative. It operates a fully open access publishing model which allows open global access to its published content. This model is supported through Article Processing Charges. Wireless Communications and Mobile Computing is included in many leading abstracting and indexing databases:ACM Digital Library Advanced Polymers Abstracts Ceramics Abstracts/World Ceramics Abstracts Computer and Information Systems Abstracts Computer Science Index CSA Civil Engineering Abstracts CSA Technology Research Database Current Contents - Engineering, Computing and Technology DBLP Computer Science Bibliography Directory of Open Access Journals (DOAJ) Earthquake Engineering Abstracts Ei Compendex Engineered Materials Abstracts Engineering Village INSPEC International Aerospace Abstracts Journal Citation Reports - Science Edition Materials Business File Mechanical and Transportation Engineering Abstracts METADEX Science Citation Index Expanded Scopus The most recent Impact Factor for Wireless Communications and Mobile Computing is 1.899 according to the 2016 Journal Citation Reports released by Clarivate Analytics in 2017

An Efficient Ray-Based Modeling Approach for Scattering from Reconfigurable Intelligent Surfaces

Reconfigurable Intelligent Surfaces (RISs), which can be implemented using metasurface technology or reflect/ transmit antenna array technology, have garnered significant attention in research studies focused on both their technological aspects and potential applications. While various modeling approaches have been proposed - ranging from electromagnetic simulations and analytical integral formulations to simplified approaches based on scattering matrix theory - there remains a great need for efficient and electromagnetically-consistent macroscopic models that can accurately simulate scattering from RISs, particularly for realistic simulations of RIS-based wireless networks. Building on previous work based on the characterization of the RIS through a surface impedance (or ”spatial modulation”) function and a few parameters, in the present paper we propose a fully ray-based approach for the computation of the re-radiated field that can be easily embedded in efficient, forward ray tracing (also known as ”ray launching”) models. We validate the proposed model by comparison to well established methods available in the literature. Results show that, although the considered method is based on a completely different formulation and is much more efficient than integral formulation methods, results are almost indistinguishable in some benchmark cases

Ray Tracing Algorithm for Accurate Solar Irradiance Prediction in Urban Areas

A ray tracing algorithm has been developed to model solar radiation interaction with complex urban environments and, in particular, its effects, including the total irradiance on each surface and overall dissipated power contribution. The proposed model accounts for multiple reflection and diffuse scattering interactions and is based on a rigorous theory, so that the overall power balance is satisfied at the generic surface element. Such approach is validated against measurements in the present work in simple reference scenarios. The results show the importance of multiple-bounce interactions and diffuse scattering to obtain reliable solar irradiance and heat dissipation estimates in urban areas