The use of millimeter-wave (mm-wave) frequency bands for fifth-generation (5G) cellular mobile communications has led to intense interest from academia and industry over these spectrum resources. Despite extensive measurement campaigns and channel modeling efforts, there is a lack of deterministic backscattering models addressing the impact of the size and orientation of static scatterers on the radio channel. In this article, two 3-D computationally efficient models for calculating backscattering based on the Fresnel integrals and the error function are proposed and validated both against simulations and measurements. In addition, applying the same methodology, state-of-the-art mm-wave blockage (forward-scattering) models are modified to capture backscattered fields. Furthermore, both the introduced and the modified models preserve the structure of geometry-based stochastic channel models (GSCMs) and thus their implementation in system-level simulators is substantially beneficial due to their good accuracy and short computation time.

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Computationally Efficient Millimeter-Wave Backscattering Models: A Single-Scattering Model

Geometry-based stochastic channel models (GSCMs) are suitable models at millimeter-wave (mm-wave) frequencies. Proper forward-scattering and back-scattering modeling is needed in order to realize realistic channel assessments. In this paper, a recently-proposed back-scattering model, 3D Fresnel, goes through further investigations: first, we investigate the impact of frequency in the results of a single scenario and, second, we study the effect of multiple surfaces. In both cases, the model shows good agreement with respect to the Physical Optics (PO) reference model.

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On a Fresnel-Integrals-Based Back-Scattering Model at Millimeter-Waves

The so-called e-wall is a recently introduced concept with the implementation goal of making a flexible and cost-efficient infrastructure for next generation wireless communication systems in indoor environments. This paper discusses the importance of the e-wall concept and presents some initial attempts to realize it.

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Realizing the E-Wall Concept for Indoor 5G

In the above article <xref ref-type="bibr" rid="ref1">[1]</xref>, the authors have become aware of a number of errors that require correction. In the following, we address them by order of appearance in the text. Note that the errors in equations and/or tables do not in any way affect the results and conclusions in <xref ref-type="bibr" rid="ref1">[1]</xref>.

Corrections to “Computationally Efficient Millimeter-Wave Backscattering Models: A Single-Scattering Model”

In the above article <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , the authors have become aware of a number of errors that require correction. In the following, we address them by order of appearance in the text. Note that the errors in equations and/or tables do not in any way affect the results and conclusions in <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . 

Corrections to “Computationally Efficient Millimeter-Wave Backscattering Models: A Single-Scattering Model” [Aug 20 6306-6316]

The millimeter-wave (mm-wave) frequency spectrum is envisioned as a way to meet the ambitious and stringent goals of the fifth-generation of mobile communications (5G). Therefore, proper characterization of environments of different nature is capital to gain insight into how such systems can become a reality. In this paper, the new concept of environment-embedded radiation pattern is introduced and worked out in a measurement campaign at 28 GHz. Scenarios with isolated large metallic objects and people have been designed to capture scattering, specular reflection, and diffraction phenomena, all incorporated in the embedded radiation patterns. The use of such environment-embedded radiation patterns is proposed for future mm-wave environments where the rich multipath assumption does not hold.

Environment-Embedded Radiation Patterns at Millimeter-Wave Frequencies

Deployable networks are foreseen to be one of the key technologies for public safety in fifth generation (5G) mobile communications and beyond. They can be used to complement the existing public cellular networks to provide temporary and on-demand connectivity in emergency situations. However, operating deployable networks in coexistence with public cellular networks can be challenging from an interference perspective. To gain insights on the deployment strategy for deployable networks, in this article, we present an extensive numerical study of coverage and interference analysis, considering four different co-existence scenarios and different types of deployable base stations (BSs), i.e., BS on a truck and BS on an Unmanned Aerial Vehicle (UAV). Our simulation results show that deploying deployable BSs in rural scenarios can provide good coverage to meet the service requirement for mission critical (MC) users. In addition, the interference impact is only substantial when the deployable and public networks are close to each other. Finally, allowing the MC users to access the public network can be of vital importance to guarantee their service when the interference level between public and deployable network is very high.

Deployable Networks for Public Safety in 5G and Beyond: A Coverage and Interference Study

This article introduces the FORMAT array, a reconfigurable millimeter-wave antenna array platform based on antenna tiles. FORMAT stands for Flexible Organization and Reconfiguration of Millimeter-wave Antenna Tiles, which is a unique hardware solution aiming to implement and demonstrate a variety of antenna array concepts, as well as different array architectures and configurations from the same basic module, providing even benchmark between different solutions and thus valuable insights into fifth-generation (5G) and beyond-5G antenna systems. The combination of a minimum-sized $2\times 2$ tile with 3D-printed frame parts enables antenna arrays of a variety of sizes, allows multiple beamforming architectures, and a range of different antenna element positioning in the array. The hardware implementation is thoroughly described, with a few different array assemblies being manufactured and measured, validating their antenna performance with over-the-air measurements. Finally, using FORMAT hardware as both base station and user equipment, a 5-m wireless communication link was set up, achieving 4.8 Gbps downlink speed with QAM64 modulation.

Adrian Lahuerta-Lavieja

Papers

Computationally Efficient Millimeter-Wave Backscattering Models: A Single-Scattering Model

On a Fresnel-Integrals-Based Back-Scattering Model at Millimeter-Waves

Environment-Embedded Radiation Patterns at Millimeter-Wave Frequencies

Deployable Networks for Public Safety in 5G and Beyond: A Coverage and Interference Study

FORMAT: A Reconfigurable Tile-Based Antenna Array System for 5G and 6G Millimeter-Wave Testbeds