Digital Communications for 5G and beyond Wireless Communication Systems

A special issue of Electronics (ISSN 2079-9292). This special issue belongs to the section "Microwave and Wireless Communications".

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 10945

Special Issue Editor


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Guest Editor
Department of Informatics and Telecommunications, University of Peloponnese, 22100 Tripoli, Greece
Interests: wireless communications; digital communications; MIMO Systems; wireless; cooperative communications; cognitive radio
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Special Issue Information

Dear Colleagues,

Fifth generation (5G) wireless communication is happening, thus making the internet significantly faster and bringing next-generation wireless connectivity to millions of people. The global pandemic has also accelerated the push to innovative, high-quality services for wireless providers around the world, and the future belongs to those who can innovate and capitalize on the opportunities of the current and future generation of wireless digital communications.  Wireless networks are also becoming greener, with both carbon intensity and overall emissions decreasing.  Machine-learning (ML) and artificial intelligence (AI) techniques are envisaged to render current and future wireless networks more responsive to customer needs. With 5G deployment, high-speed applications such as video and gaming will download and interact with the user in real time. Equipment that requires low-latency, immediate response, such as vehicles in traffic and robots involved in time- and life-critical tasks, will be able to operate with virtually no wait, meaning less than a millisecond for a network connection versus several tens of milliseconds it takes today.  Motivated by the above, the objective of this Special Issue is to present studies in the emerging field of digital communications for 5G and beyond wireless communications systems. Researchers are invited to submit their manuscripts to this Special Issue and contribute their models, proposals, reviews, and studies.

Dr. Konstantinos Peppas
Guest Editor

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Keywords

  • Digital communications and signal processing for current and future wireless communications systems
  • Information theoretical results for 5G and beyond communications systems
  • Diversity, cooperative diversity
  • Green Communications, Wireless power transfer techniques
  • Free Space Optical Communications
  • Physical Layer Security
  • Machine Learning Techniques for Digital Communications
  • Digital Communications for Sensor Networks

Published Papers (6 papers)

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Research

20 pages, 501 KiB  
Article
On the Fast DHT Precoding of OFDM Signals over Frequency-Selective Fading Channels for Wireless Applications
by Kelvin Anoh, Cagri Tanriover, Moisés V. Ribeiro, Bamidele Adebisi and Chan Hwang See
Electronics 2022, 11(19), 3099; https://doi.org/10.3390/electronics11193099 - 28 Sep 2022
Cited by 3 | Viewed by 1205
Abstract
Due to high power consumption and other problems, it is unlikely that orthogonal frequency-division multiplexing (OFDM) would be included in the uplink of the future 6G standard. High power consumption in OFDM systems is motivated by the high peak-to-average power ratio (PAPR) introduced [...] Read more.
Due to high power consumption and other problems, it is unlikely that orthogonal frequency-division multiplexing (OFDM) would be included in the uplink of the future 6G standard. High power consumption in OFDM systems is motivated by the high peak-to-average power ratio (PAPR) introduced by the inverse Fourier transform (IFFT) processing kernel in the time domain. Linear precoding of the symbols in the frequency domain using discrete Hartley transform (DHT) could be used to minimise the PAPR problem, however, at the cost of increased complexity and power consumption. In this study, we minimise the computation complexity of the DHT precoding on OFDM transceiver schemes and the consequent power consumption. We exploit the involutory properties of the processing kernels to process the DHT and IFFT as a single-processing block, thus reducing the system complexity and power consumption. These also enable a novel power-saving receiver design. We compare the results to three other precoding schemes and the standard OFDM scheme as the baseline; while improving the power consumption efficiency of a Class-A power amplifier from 4.16% to 16.56%, the bit error ratio is also enhanced by up to 5 dB when using a 12rate error-correction coding and 7 dB with interleaving. Full article
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14 pages, 431 KiB  
Article
Performance Analysis of Mixed Rayleigh and F Distribution RF-FSO Cooperative Systems with AF Relaying
by Liqiang Han, Xuemei Liu, Yawei Wang and Boyu Li
Electronics 2022, 11(15), 2299; https://doi.org/10.3390/electronics11152299 - 23 Jul 2022
Cited by 3 | Viewed by 1357
Abstract
This paper proposes a dual-hop mixed radio frequency-free-space optical (RF-FSO) cooperative system with amplify-and-forward (AF) relaying. The RF link is subject to Rayleigh fading and the FSO link is assumed to follow F-distributed fading with pointing error. The different types of detection, [...] Read more.
This paper proposes a dual-hop mixed radio frequency-free-space optical (RF-FSO) cooperative system with amplify-and-forward (AF) relaying. The RF link is subject to Rayleigh fading and the FSO link is assumed to follow F-distributed fading with pointing error. The different types of detection, including intensity modulation with direct detection (IM/DD) and coherent heterodyne detection (HD), are considered. The closed-form expressions for the cumulative distribution function (CDF), the moment generating function (MGF), and the moments of end-to-end signal-to-noise ratio (SNR) are derived. Furthermore, closed-form expressions for the outage probability, average bit error rate (BER), and ergodic capacity are presented. Asymptotic outage probability expressions are derived to obtain additional insights into the system performance. It is shown that the HD technique exhibits better performance than an IM/DD technique. The system performance is deteriorated by atmospheric turbulence and pointing error. Finally, analytical results are confirmed by Monte Carlo simulations. Full article
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19 pages, 2069 KiB  
Article
A Low-Complexity Detector for Uplink SCMA by Exploiting Dynamical Superior User Removal Algorithm
by Shufeng Li, Yuwei Feng, Yao Sun and Zhiping Xia
Electronics 2022, 11(7), 1020; https://doi.org/10.3390/electronics11071020 - 24 Mar 2022
Cited by 6 | Viewed by 2242
Abstract
Sparse Code Multiple Access (SCMA) is capable of ameliorating the performance of wireless communication systems for massive connectivity. The sparsity of the codeword allows SCMA to employ the message-passing algorithm (MPA) at the receiver to address the connection overload. The detection complexity of [...] Read more.
Sparse Code Multiple Access (SCMA) is capable of ameliorating the performance of wireless communication systems for massive connectivity. The sparsity of the codeword allows SCMA to employ the message-passing algorithm (MPA) at the receiver to address the connection overload. The detection complexity of traditional MPA, on the other hand, is exponentially exploding with the increasing number of connected devices. In this paper, a low-complexity MPA scheme is developed with the threshold and dynamical user removal algorithm (TB-RMPA) based on shuffled MPA (SMPA). By introducing the concept of Iterative Elimination of Dominated Strategies (IEDS) in game theory, a novel method of assigning different dominance levels to users is proposed hereby, and a threshold criterion is discussed to judge the reliability of user decoding. Inspired by this, users with reliable decoding in the iterative process will be dynamically eliminated in each iteration. The numerical analysis revealed that the new TB-RMPA detector’s implementation complexity decreases significantly compared with SMPA, while the symbol error ratio performance degrades unnoticeably. Full article
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20 pages, 5004 KiB  
Article
The Effect of Rainfall on the UAV Placement for 5G Spectrum in Malaysia
by Abdulrahman M. Shalaby and Noor Shamsiah Othman
Electronics 2022, 11(5), 681; https://doi.org/10.3390/electronics11050681 - 23 Feb 2022
Cited by 3 | Viewed by 1637
Abstract
In this paper, the influence of rainfall on the deployment of UAV as an aerial base station in the Malaysia 5G network is studied. The outdoor-to-outdoor and outdoor-to-indoor path loss models are derived by considering the user’s antenna height, rain attenuation, and the [...] Read more.
In this paper, the influence of rainfall on the deployment of UAV as an aerial base station in the Malaysia 5G network is studied. The outdoor-to-outdoor and outdoor-to-indoor path loss models are derived by considering the user’s antenna height, rain attenuation, and the wall penetration loss at high frequencies. The problem of finding the UAV 3D placement is formulated with the objective to minimize the total path loss between the UAV and all users. The problem is solved by invoking two algorithms, namely Particle Swarm Optimization (PSO) and Gradient Descent (GD) algorithms. The performance of the proposed algorithms is evaluated by considering two scenarios to determine the optimum location of the UAV, namely outdoor-to-outdoor and outdoor-to-indoor scenarios. The simulation results show that, for the outdoor-to-outdoor scenario, both algorithms resulted in similar UAV 3D placement unlike for the outdoor-to-indoor scenario. Additionally, in both scenarios, the proposed algorithm that invokes PSO requires less iterations to converge to the minimum transmit power compared to that of the algorithm that invokes GD. Moreover, it is also observed that the rain attenuation increases the total path loss for high operating frequencies, namely at 24.9 GHz and 28.1 GHz. Hence, this resulted in an increase of UAV required transmit power. At 28.1 GHz, the presence of rain at the rate of 250 mm/h resulted in an increase of UAV required transmit power by a factor of 4 and 15 for outdoor-to-outdoor and outdoor-to-indoor scenarios, respectively. Full article
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14 pages, 973 KiB  
Article
Optimal Beamforming for IRS-Assisted SWIPT System with an Energy-Harvesting Eavesdropper
by Zhixiang Deng and Yan Pan
Electronics 2021, 10(20), 2536; https://doi.org/10.3390/electronics10202536 - 18 Oct 2021
Cited by 6 | Viewed by 1579
Abstract
In this paper, we study a simultaneous wireless information and power transfer (SWIPT) system aided by the intelligent reflecting surface (IRS) technology, where an AP transmits confidential information to the legitimate information receiver (IR) in the presence of an energy harvesting (EH) receiver [...] Read more.
In this paper, we study a simultaneous wireless information and power transfer (SWIPT) system aided by the intelligent reflecting surface (IRS) technology, where an AP transmits confidential information to the legitimate information receiver (IR) in the presence of an energy harvesting (EH) receiver that could be a potential eavesdropper. We aim to maximize the secrecy rate at the legitimate IR by jointly optimizing the information beamforming vector and the energy transfer beamforming vector at the access point (AP), and the phase shift matrix at the IRS, subject to the minimum harvested power required by the EH receiver. The semi-definite relaxation (SDR) approach and the alternating optimization (AO) method are proposed to convert the original non-convex optimization problem to a series of semi-definite programs (SDPs), which are solved iteratively. Numerical results show that the achievable secrecy rate of the proposed IRS-assisted SWIPT system is higher than that of the SWIPT system without the assistance of the IRS. Full article
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14 pages, 962 KiB  
Article
Accurate and Efficient Evaluation of Bit Error Rate for Dynamic Directional Modulation for Standard Modulation Schemes
by Josep Parrón, Edith Cabrera-Hernandez and Alan Tennant
Electronics 2021, 10(7), 776; https://doi.org/10.3390/electronics10070776 - 25 Mar 2021
Viewed by 1789
Abstract
Directional modulation (DM) has been proposed as a technique to enhance physical layer security of wireless transmissions. In DM, the improvement of security is achieved by increasing the transmitted power in such a way that the bit error rate (BER) is degraded in [...] Read more.
Directional modulation (DM) has been proposed as a technique to enhance physical layer security of wireless transmissions. In DM, the improvement of security is achieved by increasing the transmitted power in such a way that the bit error rate (BER) is degraded in the observation angles out of the desired secure direction. The performance of DM in terms of BER is typically evaluated by transmitting a stream of symbols for every observation angle, but this approach can be time consuming. In this communication, we propose an approach to evaluate, accurately and efficiently, the BER of dynamic DM (DDM) for standard modulation schemes. Several DDM configurations will be tested to illustrate the benefits and limitations of the evaluation method. The proposed approach is also used to present a non-iterative DDM synthesis with restrictions in the BER response. Full article
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