Research

16 pages, 3635 KiB

Open AccessArticle

Millimeter-Wave Channel Measurements and Path Loss Characterization in a Typical Indoor Office Environment

by Lorenzo Rubio, Vicent M. Rodrigo Peñarrocha, Marta Cabedo-Fabres, Bernardo Bernardo-Clemente, Juan Reig, Herman Fernández, Jesús R. Pérez, Rafael P. Torres, Luis Valle and Óscar Fernández

Electronics 2023, 12(4), 844; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics12040844 - 07 Feb 2023

Cited by 3 | Viewed by 1806

Abstract

In this paper, a path loss characterization at millimeter-wave (mmWave) frequencies is performed in a typical indoor office environment. Path loss results were derived from propagation channel measurements collected in the 25–40 GHz frequency band, in both line-of-sight (LOS) and obstructed-LOS (OLOS) propagation [...] Read more.

In this paper, a path loss characterization at millimeter-wave (mmWave) frequencies is performed in a typical indoor office environment. Path loss results were derived from propagation channel measurements collected in the 25–40 GHz frequency band, in both line-of-sight (LOS) and obstructed-LOS (OLOS) propagation conditions. The channel measurements were performed using a frequency-domain channel sounder, which integrates an amplified radio over fiber (RoF) link to avoid the high losses at mmWave. The path loss was analyzed in the 26 GHz, 28 GHz, 33 GHz and 38 GHz frequency bands through the close-in free space reference distance (CI) and the floating-intercept (FI) models. These models take into account the distance dependence of the path loss for a single frequency. Nevertheless, to jointly study the distance and frequency dependence of the path loss, multi-frequency models were considered. The parameters of the ABG (A-alpha, B-beta and G-gamma) and the close-in free space reference distance with frequency path loss exponent (CIF) models were derived from the channel measurements in the whole 25–40 GHz band under the minimum mean square error (MMSE) approach. The results show that, in general, there is some relationship between the model parameters and the frequency. Path loss exponent (PLE) values smaller than the theoretical free space propagation were obtained, showing that there are a waveguide effect and a constructive interference of multipath components (MPCs). Since the measurements were obtained in the same environment and with the same configuration and measurement setup, it is possible to establish realistic comparisons between the model parameters and the propagation behavior at the different frequencies considered. The results provided here allow us to have a better knowledge of the propagation at mmWave frequencies and may be of interest to other researchers in the simulation and performance evaluation of future wireless communication systems in indoor hotspot environments. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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11 pages, 532 KiB

Open AccessFeature PaperArticle

A Formulation of the Log-Logistic Distribution for Fading Channel Modeling

by Iván Sánchez and Francisco Javier López-Martínez

Electronics 2022, 11(15), 2409; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics11152409 - 02 Aug 2022

Cited by 5 | Viewed by 1655

Abstract

In some scenarios, the log-logistic (LL) distribution is shown to provide the best fit to field measurements in the context of wireless channel modeling. However, a fading channel model based on the LL distribution has not been formulated yet. In this work, we [...] Read more.

In some scenarios, the log-logistic (LL) distribution is shown to provide the best fit to field measurements in the context of wireless channel modeling. However, a fading channel model based on the LL distribution has not been formulated yet. In this work, we introduce the

L

-distribution as a reformulation of the LL distribution for channel modeling purposes. We provide closed-form expressions for its PDF, CDF, and moments. Performance analysis of wireless communication systems operating under

L

-fading channels is exemplified, providing exact and asymptotic expressions for relevant metrics such as the outage probability and the average capacity. Finally, important practical aspects related to the use of the

L

-distribution for channel fitting purposes are discussed in two contexts: (i) millimeter-wave links with misaligned gain, and (ii) air–ground channels in unmanned aerial vehicle communications. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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14 pages, 2781 KiB

Open AccessArticle

High-Resolution Delay Spread of Wide-Band Wireless Link in Long Tunnels—Theory and Experimental Verification

by Yehuda Taragin, Liat Rapaport, Niv Elkayamn, Gad A. Pinhasi and Yosef Pinhasi

Electronics 2022, 11(14), 2140; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics11142140 - 08 Jul 2022

Viewed by 1209

Abstract

The need for wireless communication appears everywhere, and with as few interruptions as possible. An extensive and in-depth study has been conducted on the limitations of wireless communication in pedestrian tunnels. Using an analytical mathematical ray tracing model, and performing tunnel measurements, with [...] Read more.

The need for wireless communication appears everywhere, and with as few interruptions as possible. An extensive and in-depth study has been conducted on the limitations of wireless communication in pedestrian tunnels. Using an analytical mathematical ray tracing model, and performing tunnel measurements, with an autonomous measuring setup, the model was validated. An extraordinary wide band was used for the experiments, which also featured optical systems to ensure accurate results. Since the tunnel is narrow, the differences between the different paths are small, and in order to distinguish them a resolution of 0.2 ns was used. The RMS delay spread,

σ_{τ}

, decreases throughout the tunnel, and at no point exceeds 1 ns. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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17 pages, 1651 KiB

Open AccessArticle

A Stochastic Confocal Elliptic-Cylinder Channel Model for 3D MIMO in Millimeter-Wave High-Speed Train Communication System

by Eva Assiimwe and Yihenew Wondie Marye

Electronics 2022, 11(13), 1948; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics11131948 - 22 Jun 2022

Cited by 4 | Viewed by 1422

Abstract

Massive MIMO technology is among the most promising solutions for achieving higher gain in 5G millimeter-wave (mmWave) channel models for high-speed train (HST) communication systems. Based on stochastic geometry methods, it is fundamental to accurately develop the associated MIMO channel model to access [...] Read more.

Massive MIMO technology is among the most promising solutions for achieving higher gain in 5G millimeter-wave (mmWave) channel models for high-speed train (HST) communication systems. Based on stochastic geometry methods, it is fundamental to accurately develop the associated MIMO channel model to access system performance. These MIMO channel models could be extended to massive MIMO with antenna arrays in more than one plane. In this paper, the proposed MIMO 3D geometry-based stochastic model (GBSM) is composed of the line of sight component (LOS), one sphere, and multiple confocal elliptic cylinders. By considering the proposed GBSM, the local channel statistical properties are derived and investigated. The impacts of the distance between the confocal points of the elliptic cylinder, mmWave frequencies of 28 GHz and 60 GHz, and non-stationarity on channel statistics are studied. Results show that the proposed 3D simulation model closely approximates the measured results in terms of stationary time. Consequently, findings show that the proposed 3D non-wide-sense stationary (WSS) model is better for describing mmWave HST channels in an open space environment. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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14 pages, 1305 KiB

Open AccessArticle

Geometric Simplifications of Natural Caves in Ray-Tracing-Based Propagation Modelling

by Roman Novak, Andrej Hrovat, Michael D. Bedford and Tomaž Javornik

Electronics 2021, 10(23), 2914; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics10232914 - 25 Nov 2021

Cited by 1 | Viewed by 1587

Abstract

Natural caves show some similarities to human-made tunnels, which have previously been the subject of radio-frequency propagation modelling using deterministic ray-tracing techniques. Since natural caves are non-uniform because of their inherent concavity and irregular limestone formations, detailed 3D models contain a large number [...] Read more.

Natural caves show some similarities to human-made tunnels, which have previously been the subject of radio-frequency propagation modelling using deterministic ray-tracing techniques. Since natural caves are non-uniform because of their inherent concavity and irregular limestone formations, detailed 3D models contain a large number of small facets, which can have a detrimental impact on the ray-tracing computational complexity as well as on the modelling accuracy. Here, we analyse the performance of ray tracing in repeatedly simplified 3D descriptions of two caves in the UK, i.e., Kingsdale Master Cave (KMC) Roof Tunnel and Skirwith Cave. The trade-off between the size of the reflection surface and the modelling accuracy is examined. Further, by reducing the number of facets, simulation time can be reduced significantly. Two simplification methods from computer graphics were applied: Vertex Clustering and Quadric Edge Collapse. We compare the ray-tracing results to the experimental measurements and to the channel modelling based on the modal theory. We show Edge Collapse to be better suited for the task than Vertex Clustering, with larger simplifications being possible before the passage becomes entirely blocked. The use of model simplification is predominantly justified by the computational time gains, with the acceptable simplified geometries roughly halving the execution time given the laser scanning resolution of 10 cm. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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21 pages, 7161 KiB

Open AccessFeature PaperArticle

A Wideband Radio Channel Sounder for Non-Stationary Channels: Design, Implementation and Testing

by Luis A. López-Valcárcel and Manuel García Sánchez

Electronics 2021, 10(15), 1838; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics10151838 - 30 Jul 2021

Cited by 1 | Viewed by 1938

Abstract

The increasing bandwidths and frequencies proposed for new mobile communications give rise to new challenges for system designers. Channel sounding and channel characterization are important tasks to provide useful information for the design of systems, protocols, and techniques to fight the propagation impairments. [...] Read more.

The increasing bandwidths and frequencies proposed for new mobile communications give rise to new challenges for system designers. Channel sounding and channel characterization are important tasks to provide useful information for the design of systems, protocols, and techniques to fight the propagation impairments. In this paper, we present a novel radio channel sounder capable of dealing with non-stationary channels. It can be operated in real-time and has a compact size to ease transport. For versatility and cost purposes, the core of the system is implemented in Field Programmable Gate Arrays (FPGAs). Three measurement campaigns have been conducted to illustrate the performance of the sounder in both static and non-static channels. In its current configuration, the sounder reaches an RF null-to-null bandwidth of 1 GHz, providing a delay resolution of 2 ns, a maximum measurable Doppler shift of 7.63 kHz, and 4.29 s of continuous acquisition time. A comparison with other channel sounders in the literature reveals that our proposal achieves a good combination of performance, cost, and size. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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15 pages, 23201 KiB

Open AccessArticle

Office Room Channel Modeling and Object Attenuation at Sub-THz Frequencies

by Brecht De Beelde, Emmeric Tanghe, Claude Desset, André Bourdoux, David Plets and Wout Joseph

Electronics 2021, 10(14), 1725; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics10141725 - 18 Jul 2021

Cited by 4 | Viewed by 1903

Abstract

Large bandwidths are needed to meet the high-throughput requirements of future wireless communication systems. These larger bandwidths are available at mmWave and sub-THz frequencies, such as the V-band ranging from 50 to 75 GHz and the D-band ranging from 110 to 170 GHz. [...] Read more.

Large bandwidths are needed to meet the high-throughput requirements of future wireless communication systems. These larger bandwidths are available at mmWave and sub-THz frequencies, such as the V-band ranging from 50 to 75 GHz and the D-band ranging from 110 to 170 GHz. In this paper, we present channel measurements in an office environment, covering the full D-band. Line-of-Sight (LOS) path loss (PL) is modeled as a function of frequency and distance. Both a single-frequency floating-intercept and multi-frequency alpha-beta-gamma model provide a good fit to the measured LOS PL data. Attenuation due to blockage of the LOS path by various desk objects, such as computer peripherals and cables, is determined, as well as attenuation due to plant obstructions. Attenuation due to an obstructed LOS path ranges from 3 dB for a single universal serial bus (USB) cable, and up to 25 dB for a laptop power supply, computer mouse, computer monitor, or plant. Because of a higher diffraction angle, the measured attenuation is higher when the distance between the antennas decreases. We measure diffraction around a computer monitor for dual polarization and verify whether communication via the reflected non Line-of-Sight path makes high-throughput wireless communication possible when the LOS path is blocked. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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15 pages, 484 KiB

Open AccessArticle

Fading Channel Models for mm-Wave Communications

by José David Vega Sánchez, Luis Urquiza-Aguiar and Martha Cecilia Paredes Paredes

Electronics 2021, 10(7), 798; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics10070798 - 27 Mar 2021

Cited by 13 | Viewed by 3206

Abstract

A realistic performance assessment of any wireless communication system requires the use of a fading channel model that reflects its main characteristics. The traditional Rayleigh and Nakagami-m models have been (and still are) the basis of most theoretical research on wireless technologies [...] Read more.

A realistic performance assessment of any wireless communication system requires the use of a fading channel model that reflects its main characteristics. The traditional Rayleigh and Nakagami-m models have been (and still are) the basis of most theoretical research on wireless technologies today, even for emerging technologies, such as millimeter-wave communications (mm-Wave). In this article, we show that the fluctuating multiple-ray (FMR) and

κ

-

μ

shadowed models had a better fit (i.e., lowest mean square error statistical test) to field measurements in outdoor environments at 28 GHz than the conventional channel models. Therefore, these generalized models are feasible alternatives that can be used as a benchmark when evaluating communication performance in mm-Wave scenarios. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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21 pages, 3259 KiB

Open AccessArticle

LoS Theoretical and Experimental MIMO Study from 1–40 GHz in Indoor Environments

by Juan Pascual-García, Maria-Teresa Martinez-Ingles, Davy P. Gaillot, Leandro Juan-Llácer and Jose-Maria Molina-Garcia-Pardo

Electronics 2020, 9(10), 1688; https://0-doi-org.brum.beds.ac.uk/10.3390/electronics9101688 - 15 Oct 2020

Cited by 1 | Viewed by 1827

Abstract

In this work, line-of-sight multiple-input multiple-output (MIMO) measurements in the frequency range from 1 GHz to 40 GHz are presented for an indoor environment in the scope of new 5G bands. For the sake of comparison, the measured radio channels are reproduced with [...] Read more.

In this work, line-of-sight multiple-input multiple-output (MIMO) measurements in the frequency range from 1 GHz to 40 GHz are presented for an indoor environment in the scope of new 5G bands. For the sake of comparison, the measured radio channels are reproduced with great accuracy using ray-tracing techniques by tuning all propagation mechanisms. The relative received power, root mean square of the delay spread (RMS DS) and K-factor provide an insight of how propagation behaves in indoor scenarios within a large and contiguous frequency band. Results show that a decay factor behaves nearly constant with frequency and the RMS DS is quite sensible to frequency. From these results, faithful one-slope 5G models are proposed. Finally, the contribution of the simulated propagation mechanisms to the radio channel is investigated which suggests that the simulation of the low-mmW radio channel can be simplified. Full article

(This article belongs to the Special Issue Channel Measurements, Modelling and Simulations for Future Wireless Communication Systems)

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