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Non-orthogonal Multiple Access Techniques in Emerging Optical Wireless Sensor Networks

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Sensor Networks".

Deadline for manuscript submissions: closed (3 July 2023) | Viewed by 13953

Special Issue Editors


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Guest Editor
Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg, 1855 Luxembourg, Luxembourg
Interests: convex/nonconvex optimizations; wireless communication; 5G/6G; ambient backscatter communications; intelligent reconfigurable surfaces; artificial intelligence/machine learning; Internet of Things
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Electrical Engineering Department, University of Colorado Denver, Denver, CO 80204, USA
Interests: reconfigurable intelligent surface-aided networks; heterogeneous networks; massive MIMO; cooperative MIMO communications; energy harvesting; full-duplex communications; cognitive radio; small-cell; non-orthogonal multiple access (NOMA); secure PHY; UAV networks
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Non-orthogonal multiple access (NOMA) has gained considerable interest from both academia and industrial experts to address the unprecedented requirements for high data rate, ultra-low latency, high bandwidth efficiency and massive user access. NOMA has been envisioned as a key enabling technique which offers several appealing benefits, such as massive connectivity, high bandwidth efficiency, high reliability, reduced latency and enhanced spectrum efficiency. The baseline idea of NOMA is to accommodate multiple users using the same resource block, such as space, frequency and time. NOMA encourages spectrum sharing same as the concept of cognitive radio networks. NOMA simultaneously adjusts a multitude of users through superposition coding and successive interference cancellation (SIC), attaining enhanced user fairness and high spectral efficiency. It is also worth mentioning that NOMA has proven its stature by showing compatibility with various 5G scenarios such as Internet-of-Things (IoT) and machine-to-machine communication. Additionally, NOMA gives enhanced performance when it is incorporated with other wireless communication techniques like beamforming, multiple-input multiple-output (MIMO), massive-MIMO, cooperative communications, network coding, space-time coding, cognitive radios, full-duplex, etc. Apart from these benefits, there are still several open challenges (i.e., practical impairments like channel estimation, cross-layer optimization, coexistence with other conventional techniques and low complexity algorithms for user clustering) to realize the full potential of NOMA in practical systems. Similarly, spectrum sharing between users can cause strong interference which raises the need for sophisticated digital signal processing algorithms for multiuser detection and interference control. Furthermore, the enhanced sensing capability of multiple users through NOMA, leads to privacy and security concerns. Thus, there is a need to develop a set of security mechanisms from the physical to application layer in order to build an effective, efficient and robust system.

This Special Issue aims to provide a forum to bring together latest research innovations from both practitioners and leading researchers from diversified interests to unlock the potential and address breakthrough novelties of NOMA systems. We invite prospective authors to contribute articles of high quality scientific research based on theory and experiments for NOMA. The key focus of this feature topic is to bridge the gap between theory, practice in design and applications while tailoring NOMA to integrate in the promising optical wireless technologies. We seek original research articles, surveys and reviews on topics given, but not limited to:

  • Performance analysis of NOMA;
  • Hardware design and optimization for NOMA;
  • Channel coding and modulation for NOMA;
  • MIMO and massive MIMO techniques for NOMA;
  • Integration of NOMA with emerging optical wireless technologies;
  • Security issues in NOMA;
  • NOMA for Terahertz communications;
  • NOMA for unmanned aerial vehicles (UAVs);
  • NOMA for 5G and B5G;
  • VLC NOMA;
  • NOMA for WPT, LPT, SWIPT and SLIPT;
  • Intelligent reflecting surfaces and meta-surfaces for NOMA;
  • Emerging applications and challenges of NOMA;
  • Practical implementation of NOMA;
  • Resource allocation for NOMA;
  • Cognitive networking with NOMA;
  • Signal processing algorithms for NOMA;
  • NOMA for satellite communication;
  • NOMA for backscatter communication;
  • Artificial intelligence and machine learning algorithms for NOMA;
  • NOMA for D2D communication;
  • NOMA for intelligent transportation systems;
  • NOMA for underwater sensor communication;
  • NOMA for Internet-of-Things (IoT).

Dr. Syed Agha Hassnain Mohsan
Dr. Wali Ullah Khan
Dr. Dinh-Thuan Do
Guest Editors

Manuscript Submission Information

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Keywords

  • NOMA
  • wireless communication
  • 5G
  • internet of things
  • spectral efficiency
  • energy efficiency
  • signal processing

Published Papers (5 papers)

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Research

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18 pages, 11013 KiB  
Article
An Online Hashing Algorithm for Image Retrieval Based on Optical-Sensor Network
by Xiao Chen, Yanlong Li and Chen Chen
Sensors 2023, 23(5), 2576; https://doi.org/10.3390/s23052576 - 25 Feb 2023
Cited by 1 | Viewed by 1425
Abstract
Online hashing is a valid storage and online retrieval scheme, which is meeting the rapid increase in data in the optical-sensor network and the real-time processing needs of users in the era of big data. Existing online-hashing algorithms rely on data tags excessively [...] Read more.
Online hashing is a valid storage and online retrieval scheme, which is meeting the rapid increase in data in the optical-sensor network and the real-time processing needs of users in the era of big data. Existing online-hashing algorithms rely on data tags excessively to construct the hash function, and ignore the mining of the structural features of the data itself, resulting in a serious loss of the image-streaming features and the reduction in retrieval accuracy. In this paper, an online hashing model that fuses global and local dual semantics is proposed. First, to preserve the local features of the streaming data, an anchor hash model, which is based on the idea of manifold learning, is constructed. Second, a global similarity matrix, which is used to constrain hash codes is built by the balanced similarity between the newly arrived data and previous data, which makes hash codes retain global data features as much as possible. Then, under a unified framework, an online hash model that integrates global and local dual semantics is learned, and an effective discrete binary-optimization solution is proposed. A large number of experiments on three datasets, including CIFAR10, MNIST and Places205, show that our proposed algorithm improves the efficiency of image retrieval effectively, compared with several existing advanced online-hashing algorithms. Full article
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16 pages, 2795 KiB  
Article
Research on Power Allocation in Multiple-Beam Space Division Access Based on NOMA for Underwater Optical Communication
by Yanlong Li, Syed Agha Hassnain Mohsan, Xiao Chen, Riffat Tehseen, Shuaixing Li and Jianzhao Wang
Sensors 2023, 23(3), 1746; https://doi.org/10.3390/s23031746 - 03 Feb 2023
Cited by 5 | Viewed by 1944
Abstract
To meet the transmission requirements of different users in a multiple-beam access system for underwater optical communication (UWOC), this paper proposes a novel multiple-beam space division multiple access (MB-SDMA) system by utilizing a directional radiation communication beam of the hemispherical LED arrays. The [...] Read more.
To meet the transmission requirements of different users in a multiple-beam access system for underwater optical communication (UWOC), this paper proposes a novel multiple-beam space division multiple access (MB-SDMA) system by utilizing a directional radiation communication beam of the hemispherical LED arrays. The system’s access users in the different beams are divided into two categories: the users with a single beam and the users with multiple beams. We also propose a power allocation algorithm that guarantees the quality of service (QoS) for single beam and multiple beam access, especially the QoS for edge users, and fairness for all users. An optimization model of power distribution under the constraints of specific light-emitting diode (LED) emission power is established for two scenarios, which ensure the user QoS for edge users and the max–min fairness for fair users. Using the Karush–Kuhn–Tucker (KKT) condition and the bisection method, we obtain the optimal power allocation expression for the two types of users in the optimization model. Through simulation, we verify that the proposed user classification and power allocation method can ensure the fairness of fair users on the premise of ensuring the QoS of edge users. At the same time, we know that the number of users will affect the improvement of the minimum rate, and the throughput of the non-orthogonal multiple access (NOMA) system is greatly improved compared with the traditional orthogonal multiple access (OMA) systems. Full article
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23 pages, 1230 KiB  
Article
Empowering Intelligent Surfaces and User Pairing for IoT Relaying Systems: Outage Probability and Ergodic Capacity Performance
by Huu-Phuc Dang, Minh-Sang Van Nguyen, Dinh-Thuan Do, Minh-Hoa Nguyen, Minh-Triet Pham and Anh-Tuan Kim
Sensors 2022, 22(17), 6576; https://doi.org/10.3390/s22176576 - 31 Aug 2022
Cited by 1 | Viewed by 1481
Abstract
The evolution of Internet of Things (IoT) networks has been studied owing to the associated benefits in useful applications. Although the evolution is highly helpful, the increasing day-to-day demands of mobile users have led to immense requirements for further performance improvements such as [...] Read more.
The evolution of Internet of Things (IoT) networks has been studied owing to the associated benefits in useful applications. Although the evolution is highly helpful, the increasing day-to-day demands of mobile users have led to immense requirements for further performance improvements such as efficient spectrum utilization, massive device connectivity, and high data rates. Fortunately, reconfigurable intelligent surfaces (RIS) and non-orthogonal multiple access (NOMA) techniques have recently been introduced as two possible current-generation emerging technologies with immense potential of addressing the above-mentioned issues. In this paper, we propose the integration of RIS to the existing techniques (i.e., NOMA and relaying) to further enhance the performance for mobile users. We focus on a performance analysis of two-user group by exploiting two main performance metrics including outage probability and ergodic capacity. We provide closed-form expressions for both performance metrics to highlight how NOMA-aided RIS systems provide more benefits compared with the benchmark based on traditional orthogonal multiple access (OMA). Monte-Carlo simulations are performed to validate the correctness of obtained expressions. The simulations show that power allocation factors assigned to two users play a major role in the formation of a performance gap among two users rather than the setting of RIS. In particular, the strong user achieves optimal outage behavior when it is allocated 35% transmit power. Full article
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Review

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30 pages, 4601 KiB  
Review
NOMA-Based VLC Systems: A Comprehensive Review
by Syed Agha Hassnain Mohsan, Muhammad Sadiq, Yanlong Li, Alexey V. Shvetsov, Svetlana V. Shvetsova and Muhammad Shafiq
Sensors 2023, 23(6), 2960; https://doi.org/10.3390/s23062960 - 09 Mar 2023
Cited by 20 | Viewed by 3808
Abstract
The enhanced proliferation of connected entities needs a deployment of innovative technologies for the next generation wireless networks. One of the critical concerns, however, is the spectrum scarcity, due to the unprecedented broadcast penetration rate nowadays. Based on this, visible light communication (VLC) [...] Read more.
The enhanced proliferation of connected entities needs a deployment of innovative technologies for the next generation wireless networks. One of the critical concerns, however, is the spectrum scarcity, due to the unprecedented broadcast penetration rate nowadays. Based on this, visible light communication (VLC) has recently emerged as a viable solution to secure high-speed communications. VLC, a high data rate communication technology, has proven its stature as a promising complementary to its radio frequency (RF) counterpart. VLC is a cost-effective, energy-efficient, and secure technology that exploits the current infrastructure, specifically within indoor and underwater environments. Yet, despite their appealing capabilities, VLC systems face several limitations which constraint their potentials such as LED’s limited bandwidth, dimming, flickering, line-of-sight (LOS) requirement, impact of harsh weather conditions, noise, interference, shadowing, transceiver alignment, signal decoding complexity, and mobility issue. Consequently, non-orthogonal multiple access (NOMA) has been considered an effective technique to circumvent these shortcomings. The NOMA scheme has emerged as a revolutionary paradigm to address the shortcomings of VLC systems. The potentials of NOMA are to increase the number of users, system’s capacity, massive connectivity, and enhance the spectrum and energy efficiency in future communication scenarios. Motivated by this, the presented study offers an overview of NOMA-based VLC systems. This article provides a broad scope of existing research activities of NOMA-based VLC systems. This article aims to provide firsthand knowledge of the prominence of NOMA and VLC and surveys several NOMA-enabled VLC systems. We briefly highlight the potential and capabilities of NOMA-based VLC systems. In addition, we outline the integration of such systems with several emerging technologies such as intelligent reflecting surfaces (IRS), orthogonal frequency division multiplexing (OFDM), multiple-input and multiple-output (MIMO) and unmanned aerial vehicles (UAVs). Furthermore, we focus on NOMA-based hybrid RF/VLC networks and discuss the role of machine learning (ML) tools and physical layer security (PLS) in this domain. In addition, this study also highlights diverse and significant technical hindrances prevailing in NOMA-based VLC systems. We highlight future research directions, along with provided insights that are envisioned to be helpful towards the effective practical deployment of such systems. In a nutshell, this review highlights the existing and ongoing research activities for NOMA-based VLC systems, which will provide sufficient guidelines for research communities working in this domain and it will pave the way for successful deployment of these systems. Full article
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35 pages, 4522 KiB  
Review
A Survey of Deep Learning Based NOMA: State of the Art, Key Aspects, Open Challenges and Future Trends
by Syed Agha Hassnain Mohsan, Yanlong Li, Alexey V. Shvetsov, José Varela-Aldás, Samih M. Mostafa and Abdelrahman Elfikky
Sensors 2023, 23(6), 2946; https://doi.org/10.3390/s23062946 - 08 Mar 2023
Cited by 25 | Viewed by 3434
Abstract
Non-Orthogonal Multiple Access (NOMA) has become a promising evolution with the emergence of fifth-generation (5G) and Beyond-5G (B5G) rollouts. The potentials of NOMA are to increase the number of users, the system’s capacity, massive connectivity, and enhance the spectrum and energy efficiency in [...] Read more.
Non-Orthogonal Multiple Access (NOMA) has become a promising evolution with the emergence of fifth-generation (5G) and Beyond-5G (B5G) rollouts. The potentials of NOMA are to increase the number of users, the system’s capacity, massive connectivity, and enhance the spectrum and energy efficiency in future communication scenarios. However, the practical deployment of NOMA is hindered by the inflexibility caused by the offline design paradigm and non-unified signal processing approaches of different NOMA schemes. The recent innovations and breakthroughs in deep learning (DL) methods have paved the way to adequately address these challenges. The DL-based NOMA can break these fundamental limits of conventional NOMA in several aspects, including throughput, bit-error-rate (BER), low latency, task scheduling, resource allocation, user pairing and other better performance characteristics. This article aims to provide firsthand knowledge of the prominence of NOMA and DL and surveys several DL-enabled NOMA systems. This study emphasizes Successive Interference Cancellation (SIC), Channel State Information (CSI), impulse noise (IN), channel estimation, power allocation, resource allocation, user fairness and transceiver design, and a few other parameters as key performance indicators of NOMA systems. In addition, we outline the integration of DL-based NOMA with several emerging technologies such as intelligent reflecting surfaces (IRS), mobile edge computing (MEC), simultaneous wireless and information power transfer (SWIPT), Orthogonal Frequency Division Multiplexing (OFDM), and multiple-input and multiple-output (MIMO). This study also highlights diverse, significant technical hindrances in DL-based NOMA systems. Finally, we identify some future research directions to shed light on paramount developments needed in existing systems as a probable to invigorate further contributions for DL-based NOMA system. Full article
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