Research

14 pages, 749 KiB

Open AccessArticle

Sum Rate Maximization for Intelligent Reflecting Surface-Assisted UAV-Enabled NOMA Network

by Songchao Chen, Fang Liu and Yuanan Liu

Electronics 2023, 12(17), 3616; https://doi.org/10.3390/electronics12173616 - 27 Aug 2023

Viewed by 715

In the next-generation network, intelligent reflecting surface (IRS), non-orthogonal multiple access (NOMA), and simultaneous wireless information and power transfer (SWIPT) are promising wireless communication techniques to effectively improve system sum rates. In traditional unmanned aerial vehicles (UAV) communication systems, the sum rate and [...] Read more.

In the next-generation network, intelligent reflecting surface (IRS), non-orthogonal multiple access (NOMA), and simultaneous wireless information and power transfer (SWIPT) are promising wireless communication techniques to effectively improve system sum rates. In traditional unmanned aerial vehicles (UAV) communication systems, the sum rate and coverage are greatly affected when there is an occlusion on the direct transmission link. To solve this problem, the IRS technology is introduced to improve the poor channel conditions. However, most of the previous research on IRS-assisted UAV to optimize system sum rate only considers frameworks that utilize the partially joint-combining techniques of IRS, NOMA, and SWIPT. In this paper, in order to further improve the sum rate of the system, we simultaneously integrate IRS, NOMA, and SWIPT technologies and establish a sum rate maximization optimization problem when the direct link is blocked. Then, an alternative optimization (AO) algorithm based on the maximizing system sum rate is proposed to solve the non-convex optimization problem, in which the IRS location and phase, the reflecting amplitude coefficient, UAV forwarding altitude, and power splitting factor are considered. To let the non-convex and non-linear function be transformed into a convex one, we first use an iterative approach to optimize the position of the IRS. After that, an optimization problem is constructed to maximize the system sum rate with the constraints of the IRS phase shifts, successful successive interference cancellation (SIC), maximum transmit power of base station (BS), and UAV. Numerical results show that the proposed algorithm outperforms the traditional orthogonal multiple access (OMA) and algorithms without IRS-assisted links in terms of the system sum rate. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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13 pages, 593 KiB

Open AccessFeature PaperArticle

Budgeted Thompson Sampling for IRS Enabled WiGig Relaying

by Sherief Hashima, Kohei Hatano, Eiji Takimoto and Ehab Mahmoud Mohamed

Electronics 2023, 12(5), 1146; https://doi.org/10.3390/electronics12051146 - 27 Feb 2023

Cited by 3 | Viewed by 986

Abstract

Intelligent reconfigurable surface (IRS) is a competitive relaying technology to widen the WiGig coverage range, as it offers an effective means of addressing blocking issues. However, selecting the optimal IRS relay for maximum attainable data rate is a time-consuming process, as it requires [...] Read more.

Intelligent reconfigurable surface (IRS) is a competitive relaying technology to widen the WiGig coverage range, as it offers an effective means of addressing blocking issues. However, selecting the optimal IRS relay for maximum attainable data rate is a time-consuming process, as it requires WiGig beamforming training (BT) to tune the phase shifts (PSs) for WiGig base station (WGBS) and IRS relays. This paper proposes a self-learning-based budgeted Thomson sampling approach for IRS relay probing (BTS-IRS) to address this challenge. The BT time cost of probing the IRS relay is incorporated into the main BTS formula, where both payoff and cost posterior distributions are sampled separately, their ratio is estimated, and the arm/IRS relay with the highest ratio is decided. This enables the IRS relay to be chosen with the lowest BT time cost. Numerical results demonstrate the improved performance of the BTS-IRS relaying technique regarding BT time consumption/cost, spectral efficiency, and attainable data rate when compared to other benchmarks. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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10 pages, 1284 KiB

Open AccessCommunication

UTD-PO Solutions for the Analysis of Multiple Diffraction by Trees and Buildings When Assuming Spherical-Wave Incidence

by José-Víctor Rodríguez, María-Teresa Martínez-Inglés, Jose-Maria Molina Garcia-Pardo, Leandro Juan-Llácer and Ignacio Rodríguez-Rodríguez

Electronics 2023, 12(4), 899; https://doi.org/10.3390/electronics12040899 - 10 Feb 2023

Viewed by 891

Abstract

This paper presents two uniform theories of diffraction–physical optics (UTD-PO) formulations to undertake analysis of radiowave multiple diffraction resulting from the presence of both buildings and trees in vegetated urban areas, with the assumption of spherical-wave incidence. The solutions presented consider buildings modeled [...] Read more.

This paper presents two uniform theories of diffraction–physical optics (UTD-PO) formulations to undertake analysis of radiowave multiple diffraction resulting from the presence of both buildings and trees in vegetated urban areas, with the assumption of spherical-wave incidence. The solutions presented consider buildings modeled as knife-edges and rectangular sections (the latter being more complex and realistic) and the effect of the tree canopy (the assumption is that this exceeds the height of the average rooftop) is taken into account by adding proper attenuation factors/phasors to building diffraction phenomena. The validation of these formulations has been undertaken by comparing with other methods and measurements performed at 39 GHz on a scaled-model of the environment under analysis, consisting of an array of bricks and bonsai trees. The chief advantage of the solutions put forward is that because of recursion, the calculations only include single diffractions. This avoids any requirement for higher-order diffraction terms in the diffraction coefficients, which means less computer time/power is demanded. The results of this work may be useful when planning future mobile communication systems, including 6G networks and beyond. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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20 pages, 6209 KiB

Open AccessCommunication

Using the Uniform Theory of Diffraction to Analyze Radio Wave Propagation along Urban Street Canyons for Device-to-Device Communication

by Elena Brugarolas-Ortiz, Ignacio Rodríguez-Rodríguez, José-Víctor Rodríguez, Leandro Juan-Llácer and Domingo Pardo-Quiles

Electronics 2023, 12(3), 593; https://doi.org/10.3390/electronics12030593 - 25 Jan 2023

Viewed by 929

Abstract

This paper examines the propagation of radio waves in so-called urban street canyons through formulations based on Geometrical Optics (GO) and the Uniform Theory of Diffraction (UTD). As this type of environment comprises a street flanked by tall buildings more or less equally [...] Read more.

This paper examines the propagation of radio waves in so-called urban street canyons through formulations based on Geometrical Optics (GO) and the Uniform Theory of Diffraction (UTD). As this type of environment comprises a street flanked by tall buildings more or less equally spaced on both sides (creating a canyon-like morphology), estimating the attenuation that radio signals may experience in these scenarios is crucial to the planning of urban device-to-device (D2D) wireless communication. In this sense, the results obtained through the analysis based on GO/UTD (in the horizontal plane containing the transmitter and receiver) are validated by a comparison with experimental measurements, showing good agreement. This work demonstrates how the use of GO/UTD-based formulations can contribute to a simpler and computationally more efficient planning of D2D mobile communication systems in which the considered propagation environment can be modeled as an urban street canyon comprising rectangular and equispaced buildings. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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18 pages, 9535 KiB

Open AccessArticle

A Clutter Loss Model for Satellite Communication Systems

by Carlo G. Riva, Lorenzo Luini, Alberto Panzeri, Filippo Morandi, Laura Resteghini, Danilo De Donno, Christian Mazzucco and Renato Lombardi

Electronics 2023, 12(1), 186; https://doi.org/10.3390/electronics12010186 - 30 Dec 2022

Cited by 2 | Viewed by 2055

Abstract

Buildings and vegetation in the proximity of a terrestrial base station induce a significant additional loss, typically referred to as “clutter loss”, which sums up to free space loss and atmospheric attenuation. Clutter loss is essentially due to the radiowave reflection and diffraction [...] Read more.

Buildings and vegetation in the proximity of a terrestrial base station induce a significant additional loss, typically referred to as “clutter loss”, which sums up to free space loss and atmospheric attenuation. Clutter loss is essentially due to the radiowave reflection and diffraction caused by buildings and vegetation, and tends to reduce the interference between terrestrial systems, such as upper 6 GHz (U6G), and satellite systems operating in the same frequency bands. In fact, for example, at low elevation angles, the clutter loss could reach some tens of dB in the U6G band. A novel clutter loss model in urban and suburban environments for frequencies up to 10 GHz is proposed. The model relies on the Monte Carlo simulation approach presented in Report ITU-R P.2402-0, but some limitations have been removed to extend its applicability to more complex scenarios and possibly increase its accuracy for U6G systems. An analytical approach is also proposed to model the clutter loss statistics obtained by properly fitting the obtained statistics for the cities of London and Melbourne. Finally, the proposed model is validated by comparing its results to those obtained by a commercial ray tracer. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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20 pages, 5645 KiB

Open AccessArticle

Asynchronous Partial Gaussian Approximation Detection Algorithm for Uplink-Grouped MIMO-SCMA System

by Xue Wang, Ninghao Zhou and Jia Hou

Electronics 2022, 11(21), 3536; https://doi.org/10.3390/electronics11213536 - 30 Oct 2022

Viewed by 1004

Abstract

To relieve the impact caused by different arrival times of multiple users in the uplink MIMO-SCMA system, a grouped multiuser transmission model, according to different delays and its corresponding detection scheme, is proposed in this paper. Assuming perfect synchronization in one group, a [...] Read more.

To relieve the impact caused by different arrival times of multiple users in the uplink MIMO-SCMA system, a grouped multiuser transmission model, according to different delays and its corresponding detection scheme, is proposed in this paper. Assuming perfect synchronization in one group, a message-passing algorithm based on serial propagation (SP-MPA) is proposed to reduce the bit error rate (BER), which could transfer the updated information to the next symbol as its initial probability. Furthermore, with a more practical case, the partial Gaussian approximation method (PGA) is designed to decrease the interference resulting from the imperfect synchronization in one group. As the result, the computing complexity of the proposed PGA method could be decreased by at least 20% compared with SP-MPA and the BER could be improved by about 10%. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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18 pages, 7313 KiB

Open AccessArticle

V-Band Channel Modeling, Throughput Measurements, and Coverage Prediction for Indoor Residential Environments

by Brecht De Beelde, Andrés Almarcha, David Plets and Wout Joseph

Electronics 2022, 11(4), 659; https://doi.org/10.3390/electronics11040659 - 20 Feb 2022

Cited by 4 | Viewed by 1763

Abstract

With the increased resolution and frame rates of video recordings, in combination with the current evolution towards video-on-demand streaming services and the user expecting ubiquitous wireless connectivity, it is necessary to design wireless communication systems that allow high-rate data transfer. The large bandwidths [...] Read more.

With the increased resolution and frame rates of video recordings, in combination with the current evolution towards video-on-demand streaming services and the user expecting ubiquitous wireless connectivity, it is necessary to design wireless communication systems that allow high-rate data transfer. The large bandwidths that are available in the mmWave frequency band allow such high data rates. In this paper, we provide an experimental and simulated indoor residential radio channel model at V-band frequencies and perform packet error rate and throughput measurements at 60 GHz using IEEE 802.11ad transceivers. We compare the path loss and throughput measurements to simulations using a network performance prediction tool. The path loss measurement results using an omnidirectional transmit antenna correspond well to generic indoor mmWave channel models. Double-directional path loss measurements show that generic models underestimate path loss of non-Line-of-Sight (NLOS) links. A ray-launching algorithm is designed and validated, and used for IEEE 802.11ad throughput estimation based on link budget calculations. The link budget underestimates the achieved throughput, when comparing to adaptive-rate MCS selection in a commercial transceiver, based on the measured signal-to-noise ratio. Packet error rate measurements confirm that, even for NLOS links, throughputs exceeding 1 Gbps are possible. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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13 pages, 1519 KiB

Open AccessArticle

A Novel Cooperative Transmission Scheme in UAV-Assisted Wireless Sensor Networks

by Yue Zang, Yuyang Peng, Sangdon Park, Han Hai, Fawaz AL-Hazemi and Mohammad Meraj Mirza

Electronics 2022, 11(4), 600; https://doi.org/10.3390/electronics11040600 - 15 Feb 2022

Cited by 2 | Viewed by 1821

Abstract

In wireless sensor networks (WSNs), the efficiency of data transmission within a limited time is critical, especially for sensors designed with small batteries. In this paper, we design a cooperative transmission scheme with an energy-charging function in a WSN where an unmanned aerial [...] Read more.

In wireless sensor networks (WSNs), the efficiency of data transmission within a limited time is critical, especially for sensors designed with small batteries. In this paper, we design a cooperative transmission scheme with an energy-charging function in a WSN where an unmanned aerial vehicle (UAV) is considered for sensory data collection and energy charging. Specially, the sensor nodes are powered by the UAV for their data transmission. In the first phase, the UAV transmits the energy signal to the sensor nodes distributed on the ground. All the energy received by the sensor nodes is used to collect and transmit the sensory data to the UAV. In the second phase, local data transmissions are conducted among the collaborating sensor nodes in one cluster. In the third phase, the cooperative nodes send the collected sensory data to the UAV in the form of cooperative transmission. In the proposed scheme, we discovered that the size of the modulation constellation and the assigned time ratio of each phase were the key factors affecting the data transmission efficiency. In order to achieve the maximum data transmission, the optimal modulation constellation size and the optimal time ratio of each phase were found using the Lagrange multiplier method. Numerical results show that the proposed scheme with the optimal constellation size and the optimal time ratio can outperform the existing scheme in terms of the data transmission efficiency. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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20 pages, 4878 KiB

Open AccessArticle

Objects Detection Using Sensors Data Fusion in Autonomous Driving Scenarios

by Razvan Bocu, Dorin Bocu and Maksim Iavich

Electronics 2021, 10(23), 2903; https://doi.org/10.3390/electronics10232903 - 24 Nov 2021

Cited by 3 | Viewed by 1547

Abstract

The relatively complex task of detecting 3D objects is essential in the realm of autonomous driving. The related algorithmic processes generally produce an output that consists of a series of 3D bounding boxes that are placed around specific objects of interest. The related [...] Read more.

The relatively complex task of detecting 3D objects is essential in the realm of autonomous driving. The related algorithmic processes generally produce an output that consists of a series of 3D bounding boxes that are placed around specific objects of interest. The related scientific literature usually suggests that the data that are generated by different sensors or data acquisition devices are combined in order to work around inherent limitations that are determined by the consideration of singular devices. Nevertheless, there are practical issues that cannot be addressed reliably and efficiently through this strategy, such as the limited field-of-view, and the low-point density of acquired data. This paper reports a contribution that analyzes the possibility of efficiently and effectively using 3D object detection in a cooperative fashion. The evaluation of the described approach is performed through the consideration of driving data that is collected through a partnership with several car manufacturers. Considering their real-world relevance, two driving contexts are analyzed: a roundabout, and a T-junction. The evaluation shows that cooperative perception is able to isolate more than

90 %

of the 3D entities, as compared to approximately

25 %

in the case when singular sensing devices are used. The experimental setup that generated the data that this paper describes, and the related 3D object detection system, are currently actively used by the respective car manufacturers’ research groups in order to fine tune and improve their autonomous cars’ driving modules. Full article

(This article belongs to the Special Issue Emerging Technologies for Next Generation Wireless Communication Systems)

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