Optimization and Applications of Modern Wireless Networks and Symmetry

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Computer".

Deadline for manuscript submissions: closed (31 August 2022) | Viewed by 8887

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Guest Editor
School of Physics and Information, Fuzhou University, Fuzhou 350116, China
Interests: reliable wireless communications; channel coding for wireless communications; wirelesss physcial network coding; low-complexity channel decoding
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Guest Editor
School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
Interests: blockchain; mobile edge computing; wireless network coding
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Guest Editor
School of Information Engineering, Guangdong University of Technology, Guangzhou 510006, China
Interests: channel coding; coded modulation; wireless communication; machine learning
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Special Issue Information

Dear Colleagues,

Channel coding techniques are widely used in modern wireless communications to enhance reliability and spectral efficiency. In particular, low-density parity check (LDPC) codes and polar codes are being optimized for the next wireless standard. Moreover, over the past two decades, physical network coding was invented to improve wireless throughput, together with channel coding. This invokes a great deal of attention on the modern symmetry or asymmetry wireless communications.

Due to the future demands of IoT/5G communications, this Research Topic welcomes research that discusses channel coding, multi-access, physical network coding, and the related communication and network techniques for IoT/5G, and aims to present new research directions in the emerging fields of research.

Prof. Dr. Pingping Chen
Prof. Dr. Long Shi
Prof. Dr. Yi Fang
Guest Editors

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Published Papers (7 papers)

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Editorial

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2 pages, 159 KiB  
Editorial
Editorial of Special Issue “Optimization and Applications of Modern Wireless Networks and Symmetry”
by Pingping Chen, Long Shi and Yi Fang
Symmetry 2022, 14(9), 1825; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14091825 - 02 Sep 2022
Viewed by 833
Abstract
This book contains the successfully published submissions [...] Full article

Research

Jump to: Editorial

15 pages, 3552 KiB  
Article
New Unequal Error Protection Strategy for Image Transmission Based on Bilayer-Lengthened PLDPC Code in Half-Duplex Relay System
by Tian Gao, Min Xiao, Pingping Chen and Diyan Gao
Symmetry 2022, 14(8), 1662; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14081662 - 11 Aug 2022
Cited by 2 | Viewed by 1093
Abstract
To reduce the waste of energy in communications, unequal error protection (UEP) is used to provide asymmetric protection for messages with different levels of importance. This paper proposes new efficient strategies of UEP based on bilayer protograph-based low-density parity check (PLDPC) codes in [...] Read more.
To reduce the waste of energy in communications, unequal error protection (UEP) is used to provide asymmetric protection for messages with different levels of importance. This paper proposes new efficient strategies of UEP based on bilayer protograph-based low-density parity check (PLDPC) codes in decoding-and-forward (DF) relay systems. In particular, we jointly utilize source coding and channel coding to design UEP strategies and then save transmission energy. According to the different levels of importance of discrete cosine transform (DCT) coefficients of image and variance statistical characteristics of image sub-blocks, bilayer-lengthened PLDPC codes are exploited to protect the transmitted image information with different importance levels at the half-duplex relay system. In the end, the simulation result shows that the proposed UEP schemes achieve excellent performance gains compared to conventional equal error protection (EEP) scheme. Additionally, the complexity analysis of the UEP strategies is given. Full article
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21 pages, 4385 KiB  
Article
Unlicensed Spectrum Allocation for LTE and Wi-Fi Coexistence with HAP
by Wei Kuang Lai, Chin-Shiuh Shieh, Yuh-Chung Lin, Chun-Yi Tsai and Yu-Dai Yan
Symmetry 2022, 14(8), 1650; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14081650 - 10 Aug 2022
Cited by 2 | Viewed by 1415
Abstract
In order to accommodate the ever-increasing traffic demands, numerous approaches have been developed to improve spectrum utilization. Among others, the coexistence of LTE (Long-Term Evolution) and Wi-Fi, addressed by the 3GPP (3rd Generation Partnership Project) with hyper access points (HAPs) as bridges, is [...] Read more.
In order to accommodate the ever-increasing traffic demands, numerous approaches have been developed to improve spectrum utilization. Among others, the coexistence of LTE (Long-Term Evolution) and Wi-Fi, addressed by the 3GPP (3rd Generation Partnership Project) with hyper access points (HAPs) as bridges, is well recognized as a promising candidate solution. Aimed at improving the spectrum utilization of the unlicensed bands by following LTE-Unlicensed (LTE-U), this article contributes to the determination of the optimal time ratio, δ, for the time-division multiplexing of LTE and Wi-Fi over unlicensed bands. Symmetric allocation with a duty cycle of 50% cannot be an optimal option. Asymmetric allocation according to the quality of service (QoS) requirements and traffic demands should be considered. The problem is formulated as an optimization problem optimizing the total throughput. The lower and upper bounds of δ are obtained according to the QoS requirements of Wi-Fi and the admission control requirements of LTE. The detailed procedure for finding an adequate δ is developed and presented. A series of simulations are conducted to demonstrate the feasibility and effectiveness of the proposed approach. Simulation results show that the proposed approach improves the total throughput without compromising the fairness of Wi-Fi, as intended. Ten percent of improvement in throughput compared with LTE-U can be achieved. Full article
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16 pages, 522 KiB  
Article
A General Framework for Geometrically Uniform Codes and Signal Sets Matched to Groups
by Eduardo Michel Vieira Gomes, Edson Donizete de Carvalho, Carlos Alexandre Ribeiro Martins, Evandro Mazetto Brizola and Eduardo Brandani da Silva
Symmetry 2022, 14(6), 1214; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14061214 - 12 Jun 2022
Cited by 2 | Viewed by 1027
Abstract
Geometrically uniform codes are fundamental in communication systems, mainly for modulation. Typically, geometrically uniform codes are dependent on a given alphabet. The current work establishes the necessary and sufficient conditions for obtaining a matched labeling between a group G and a signal set [...] Read more.
Geometrically uniform codes are fundamental in communication systems, mainly for modulation. Typically, geometrically uniform codes are dependent on a given alphabet. The current work establishes the necessary and sufficient conditions for obtaining a matched labeling between a group G and a signal set S. It introduces the concept of the G-isometric signal set, allowing for the establishment of equivalences between different types of signal sets. In particular, we obtain isometries between groups and geometrically uniform codes with a minimal generator. We also draw attention to the influence of the environment metric space, the group metric, and the matched mapping on the labeling of a signal set. The results are valid for all environment metric spaces. The alphabet emerges naturally from the relationship between the signal set S and the label group derived from its symmetry group, Γ(S). Full article
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17 pages, 3790 KiB  
Article
Improving Decodability of Polar Codes by Adding Noise
by Lingjun Kong, Haiyang Liu, Wentao Hou and Bin Dai
Symmetry 2022, 14(6), 1156; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14061156 - 03 Jun 2022
Cited by 3 | Viewed by 2821
Abstract
This paper presents an online perturbed and directed neural-evolutionary (Online-PDNE) decoding algorithm for polar codes, in which the perturbation noise and online directed neuro-evolutionary noise sequences are sequentially added to the received sequence for re-decoding if the standard polar decoding fails. The new [...] Read more.
This paper presents an online perturbed and directed neural-evolutionary (Online-PDNE) decoding algorithm for polar codes, in which the perturbation noise and online directed neuro-evolutionary noise sequences are sequentially added to the received sequence for re-decoding if the standard polar decoding fails. The new decoding algorithm converts uncorrectable received sequences into error-correcting regions of their decoding space for correct decoding by adding specific noises. To reduce the decoding complexity and delay, the PDNE decoding algorithm and sole neural-evolutionary (SNE) decoding algorithm for polar codes are further proposed, which provide a considerable tradeoff between the decoding performance and complexity by acquiring the neural-evolutionary noise in an offline manner. Numerical results suggest that our proposed decoding algorithms outperform the other conventional decoding algorithms. At high signal-to-noise ratio (SNR) region, the Online-PDNE decoding algorithm improves bit error rate (BER) performance by more than four orders of magnitude compared with the conventional simplified successive cancellation (SSC) decoding algorithm. Furthermore, in the mid-high SNR region, the average normalized complexity of the proposed algorithm is almost the same as that of the SSC decoding algorithm, while preserving the decoding performance gain. Full article
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12 pages, 405 KiB  
Article
A CNN-MPSK Demodulation Architecture with Ultra-Light Weight and Low-Complexity for Communications
by Bingrui Wang, Zhijian Lin and Xingang Zhang
Symmetry 2022, 14(5), 873; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14050873 - 25 Apr 2022
Cited by 1 | Viewed by 1736
Abstract
Modulation is an indispensable component in modern communication systems and multiple phase shift keying (MPSK) is widely studied to improve the spectral efficiency. It is of great significance to study the MPSK modulations of symmetric phases in practice. Based on convolutional neural networks [...] Read more.
Modulation is an indispensable component in modern communication systems and multiple phase shift keying (MPSK) is widely studied to improve the spectral efficiency. It is of great significance to study the MPSK modulations of symmetric phases in practice. Based on convolutional neural networks (CNNs), we propose a generic architecture for MPSK demodulation, referred to as CNN-MPSK. The architecture utilizes a single-layer CNN and a pooling trick to crop network parameters. In comparison with conventional coherent demodulation, the CNN-MPSK eliminates three modules, i.e., carrier multiplication, bandpass filter and sampling decision. Thus, we can avoid π-inverted phenomenon from the multiplication of two carrier waves with different phases, as the carrier multiplication is not employed. In addition, we can reduce errors introduced by sampling decision. Furthermore, we conduct bit-error-rate tests for binary-PSK, 4PSK, 8PSK, and 16PSK demodulation. Experimental results reveal that the performance of CNN-MPSK is almost the same to that of conventional coherent demodulation. However, the CNN-MPSK demodulation reduces computational complexity from O(n2) to O(n) as compared to the latter one. Additionally, the proposed scheme can be readily applied for demodulation of non-symmetric MPSK constellations that maybe distorted by linear and nonlinear impairments in communication systems. Full article
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20 pages, 3311 KiB  
Article
A Light and Anonymous Three-Factor Authentication Protocol for Wireless Sensor Networks
by Lianghong Zhu, Huaikun Xiang and Kai Zhang
Symmetry 2022, 14(1), 46; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14010046 - 30 Dec 2021
Cited by 8 | Viewed by 1637
Abstract
Recently, wireless sensor networks (WSNs) have been widely used in a variety of fields, and make people’s lives more convenient and efficient. However, WSNs are usually deployed in a harsh and insecure environment. Furthermore, sensors with limited hardware resources have a [...] Read more.
Recently, wireless sensor networks (WSNs) have been widely used in a variety of fields, and make people’s lives more convenient and efficient. However, WSNs are usually deployed in a harsh and insecure environment. Furthermore, sensors with limited hardware resources have a low capacity for data processing and communication. For these reasons, research on efficient and secure real-time authentication and key agreement protocols based on the characteristics of WSNs has gradually attracted the attention of academics. Although many schemes have been proposed, most of them cannot achieve all known security features with satisfactory performance, among which anonymity, N-Factor security, and forward secrecy are the most vulnerable. In order to solve these shortcomings, we propose a new lightweight and anonymous three-factor authentication scheme based on symmetric cryptographic primitives for WSNs. By using the automated security verification tool ProVerif, BAN-logic verification, and an informal security analysis, we prove that our proposed scheme is secure and realizes all known security features in WSNs. Moreover, we show that our proposed scheme is practical and efficient through the comparison of security features and performance. Full article
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