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These developments have the potential to foster additional innovation, facilitate future problem-solving and optimisation strategies, and ultimately contribute to mature OWC technologies. Keywords: optical communication; underwater optical wireless communication EN optical communication underwater optical wireless communication 87 90 4 08/24/23 20230801 NES 230801 Since 2011, optical wireless communication (OWC) technologies have gained momentum. These technologies include visible light communications (VLC), underwater VLC, Li-Fi, optical camera communications (OCC), visible light positioning, visible light sensing and free space optics, among others. [Extracted from the article]

Imperfect Channel State Information at the Transmitter (CSIT) is inevitable in modern wireless communication networks, and results in severe multi-user interference in multi-antenna Broadcast Channel (BC). While the capacity of multi-antenna (Gaussian) BC with perfect CSIT is known and achieved by Dirty Paper Coding (DPC), the capacity and the capacity-achieving strategy of multi-antenna BC with imperfect CSIT remain unknown. Conventional approaches therefore rely on applying communication strategies designed for perfect CSIT to the imperfect CSIT setting. In this work, we break this conventional routine and make two major contributions. First, we show that linearly precoded Rate-Splitting (RS), relying on the split of messages into common and private parts and linear precoding at the transmitter, and successive interference cancellation at the receivers, can achieve larger rate region than DPC in multi-antenna BC with partial CSIT. Second, we propose a novel scheme, denoted as Dirty Paper Coded Rate-Splitting (DPCRS), that relies on RS to split the user messages into common and private parts, and DPC to encode the private parts. We show that the rate region of DPCRS in Multiple-Input Single-Output (MISO) BC with partial CSIT is enlarged beyond that of conventional DPC and that of linearly precoded RS. Gaining benefits from the capability of RS to partially decode the interference and partially treat interference as noise, DPCRS is less sensitive to CSIT inaccuracies, networks loads and user deployments compared with DPC and other existing transmission strategies. [ABSTRACT FROM AUTHOR]

The text describes the organization of a Special Issue in the Sensors journal titled "Recent Trends and Advances in Telecommunications and Sensing." The Special Issue was based on papers presented at the 17th International Conference on Telecommunications (ConTEL) held at Graz University of Technology in Austria. The conference covered various topics related to telecommunications, including optical communications, satellite communications, IoT, and security. Nine papers were accepted for publication in the Special Issue, covering subjects such as network experimentation, optical camera communications in healthcare, and anomaly detection in firewall logs. The authors of the text are Erich Leitgeb, Maja Matijašević, Wilfried Gappmair, and Mario Kušek. [Extracted from the article]

The article discusses the telecommunication industry has evolved to provide services for new types of Internet of Things (IoT) devices in addition to basic mobile phone or internet services. Topics include the extended reality devices, sensors, and ground and aerial robots, to name a few. With the deployment of these new services, it is difficult for the wireless network to support ubiquitous connections with diverse quality-of-service (QoS) requirements.

In this correspondence, we compare the achievable throughput for the optimal strategy of dirty paper coding (DPC) to that achieved with suboptimal and lower complexity linear precoding techniques (zero-forcing and block diagonalization). Both strategies utilize all available spatial dimensions and therefore have the same multiplexing gain, but an absolute difference in terms of throughput does exist. The sum rate difference between the two strategies is analytically computed at asymptotically high SNR. Furthermore, the difference is not affected by asymmetric channel behavior when each user has a different average SNR. Weighted sum rate maximization is also considered. In the process, it is shown that allocating user powers in direct proportion to user weights asymptotically maximizes weighted sum rate. [ABSTRACT FROM AUTHOR]

Joint communications and sensing functionalities integrated into the same communication network have become increasingly relevant due to the large bandwidth requirements of next-generation wireless communication systems and the impending spectral shortage. While there exist system-level guidelines and waveform design specifications for such systems, an information-theoretic analysis of the absolute performance capabilities of joint sensing and communication systems that take into account practical limitations such as fading has not been addressed in the literature. Motivated by this, we undertake a network information-theoretic analysis of a typical joint communications and sensing system in this paper. Towards this end, we consider a state-dependent fading Gaussian multiple access channel (GMAC) setup with an additive state. The state process is assumed to be independent and identically distributed (i.i.d.) Gaussian, and non-causally available to all the transmitting nodes. The fading gains on the respective links are assumed to be stationary and ergodic and available only at the receiver. In this setting, with no knowledge of fading gains at the transmitters, we are interested in joint message communication and estimation of the state at the receiver to meet a target distortion in the mean-squared error sense. Our main contribution here is a complete characterization of the distortion-rate trade-off region between the communication rates and the state estimation distortion for a two-sender GMAC. Our results show that the optimal strategy is based on static power allocation and involves uncoded transmissions to amplify the state, along with the superposition of the digital message streams using appropriate Gaussian codebooks and dirty paper coding (DPC). This acts as a design directive for realistic systems using joint sensing and transmission in next-generation wireless standards and points to the relative benefits of uncoded communications and joint source-channel coding in such systems. [ABSTRACT FROM AUTHOR]

The concept of a person-based number is attractive due to several pressing demands in implementation of current wireless communication systems. Some of these are: sudden proliferation in number of area codes; the need for freedom from number changes due to changes in service provider, location, or area code; and demand for improved and integrated communication service for users. Some important factors that determine the efficiency of a mobility management scheme include fewer number of times that locations need to be updated, reduced amount of overhead data that represents mobility related information, and efficient storage mechanisms that allow for fast storage and retrieval of this information. In this paper, we shall outline a mobility management scheme that provides a globally unique personal number and offers important benefits in regard to the issues cited above. For an efficient implementation of such a scheme however, an investigation of its performance is required in order to estimate signaling traffic and signaling delays. This paper will focus on some recent studies conducted on an analysis of this scheme by using query and update operations as the metrics for determining average call delay and control data storage and transmission requirements. A comparative analysis is also performed with equivalent cases of query and update in the IS-41 system. This analysis provides a valuable tool to determine network management requirements in the implementation of a person-based number scheme. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This document is a foreword for a special issue of the journal Microsystem Technologies. The special issue features selected papers from the 11th International Conference on Computing, Communication and Sensor Network (CCSN) held in September 2022 at Utkal University in Bhubaneswar, Odisha, India. The conference covered various interdisciplinary areas such as computing, communication, sensor networks, and circuit designs. The papers included in this special issue have undergone a rigorous review process and were selected for publication. The foreword expresses the hope that readers will find the papers informative. [Extracted from the article]

For the transmission of data at high speed, the requirement of using a larger bandwidth increases due to the rise in wireless communication technologies like smart devices, mobiles, etc. An abrupt increase in the requirement for internet data due to an increase in internet users demanded time-to-time upgrades in available techniques. A significant modernization has been done by technology in mobile and wireless communication and networking fields. Therefore, the development of mobile communication began with the First Generation (1G) and has progressed continuously to the Fifth Generation (5G). To address the weaknesses of previous generations, each successive generation has been developed with improvements. Fifth Generation (5G) is the latest technology in wireless communication cellular systems, providing the highest internet speeds to everyone, anywhere, anytime. 5G has attracted many global researchers, universities, and research institutes to invent new techniques for enhancement in channel capacity and spectrum utilization of communication systems. This paper describes the evolution of cellular networks, expectations from 5G, the challenges and advantages of 5G, and the techniques on which 5G relies. [ABSTRACT FROM AUTHOR]

This paper focuses on wireless-powered communication systems, which are increasingly relevant in the Internet of Things (IoT) due to their ability to extend the operational lifetime of devices with limited energy. The main contribution of the paper is a novel approach to minimize the secrecy outage probability (SOP) in these systems. Minimizing SOP is crucial for maintaining the confidentiality and integrity of data, especially in situations where the transmission of sensitive data is critical. Our proposed method harnesses the power of an improved biogeography-based optimization (IBBO) to effectively train a recurrent neural network (RNN). The proposed IBBO introduces an innovative migration model. The core advantage of IBBO lies in its adeptness at maintaining equilibrium between exploration and exploitation. This is accomplished by integrating tactics such as advancing towards a random habitat, adopting the crossover operator from genetic algorithms (GA), and utilizing the global best (Gbest) operator from particle swarm optimization (PSO) into the IBBO framework. The IBBO demonstrates its efficacy by enabling the RNN to optimize the system parameters, resulting in significant outage probability reduction. Through comprehensive simulations, we showcase the superiority of the IBBO-RNN over existing approaches, highlighting its capability to achieve remarkable gains in SOP minimization. This paper compares nine methods for predicting outage probability in wireless-powered communications. The IBBO-RNN achieved the highest accuracy rate of 98.92%, showing a significant performance improvement. In contrast, the standard RNN recorded lower accuracy rates of 91.27%. The IBBO-RNN maintains lower SOP values across the entire signal-tonoise ratio (SNR) spectrum tested, suggesting that the method is highly effective at optimizing system parameters for improved secrecy even at lower SNRs. [ABSTRACT FROM AUTHOR]

Mobile Ad Hoc Networks (MANETs) are decentralized networks where mobile nodes communicate through radio waves without fixed infrastructure. However, they are susceptible to security attacks like the black hole attack, where malicious nodes claim optimal routes to intercept packets. This paper focuses on detecting black hole attacks within MANETs using a hybrid routing protocol. Specifically, the Modified-Zone-Based Hierarchical Link State (M-ZHLS) routing protocol is proposed and evaluated against existing protocols using simulations in NS2. The proposed method employs on-demand topology information transmission and utilizes techniques like expanding ring flooding for route discovery. Simulation results demonstrate that M-ZHLS outperforms existing protocols by reducing average delay by 5%, lowering routing overhead by 4%, and increasing delivery ratio by 4.5%. Future work aims to further enhance network performance in real-time environments. [ABSTRACT FROM AUTHOR]

Wireless Mobile Ad Hoc Networks (MANETs) present topologies where nodes act as both hosts and routes, necessitating efficient routing protocols to handle frequent route updates and transmission congestion. This paper proposes a novel routing algorithm, Fuzzy Controller Ad hoc On-demand Distance Vector (FC-AODV), to address these challenges. The FC-AODV algorithm is designed to improve packet delivery ratio, throughput, end-to-end delay, packet loss, remaining energy, and routing overhead compared to the traditional AODVprotocol. Through extensive simulations using NS 2, the proposed algorithm demonstrates superior performance across varying network scenarios. Results indicate an average increase of 12.4% in packet delivery ratio, 10.27% in throughput, and a decrease of 5.37% in end-to-end delay compared to AODV. Additionally, FC-AODV reduces packet loss by 5.57%, increases remaining energy by 6.4%, and decreases routing overhead by 6.37%. Future research directions include applying the FC-AODV concept to satellite networks, exploring the integration of shortest path algorithms, and evaluating FC-AODV in real-time network environments. [ABSTRACT FROM AUTHOR]

The term "MANET," which stands for "Mobile Adhoc Network," refers to an ad hoc wireless network incorporating routing mechanism atop an ad hoc link layer network. These networks consist of wirelessly linked mobile nodes that self- configure and self-heal. Due to frequent changes in network architecture, MANET nodes have the freedom to move. Each node in the network serves as a router, forwarding traffic to specified nodes. Broadcast algorithms in wireless ad hoc networks typically follow two main approaches: static and dynamic. In the static approach, local algorithms proactively determine each node's status based on local topology information and a globally known priority function. This paper reveals that existing local broadcast algorithms based on the static approach fail to achieve a satisfactory approximation factor for the optimum solution to an NP-hard problem. However, it is demonstrated that a constant approximation factor is attainable when relative position information is available. The hybrid broadcast method dynamically determines each node's state "on-the-fly," ensuring complete delivery and maintaining a consistent value approaching the ideal outcome as closely as possible. [ABSTRACT FROM AUTHOR]

Atmospheric turbulence causes transmitted light to fade randomly, which results in irradiance scintillation fluctuations in the received signal and significantly affects the quality of wireless optical communication systems. In this paper, we investigate the propagation characteristics of a monochromatic light-emitting diode (LED) light beam through weak-to-strong turbulence. Considering the spatial incoherence of a monochromatic LED light source, the emitted light field of a monochromatic LED light source is represented by a random field multiplied by a deterministic field that follows a Gaussian distribution. Then, based on the extended-Rytov theory, a closed expression for the irradiance scintillation index under weak-to-strong turbulence is derived. In addition, the expression for the fading probability governed by the Gamma–Gamma model is given. Finally, the effects of near-earth atmospheric refractive index structural parameters, signal propagation distances, and working light wavelengths on propagation characteristics of the LED-based VLC system are simulated and compared with those of the laser-based one. The results theoretically confirm that laser light sources are more susceptible to atmospheric turbulence along the propagation path than monochromatic LED light sources. The investigation in this paper can provide theoretical support for the design of visible light communication systems in practical applications. [ABSTRACT FROM AUTHOR]

Physical-layer security (PLS) has attracted much attention in wireless communications and has been considered one of the main candidates for enhancing wireless security in future 6G networks. Recent studies in the PLS area have focused on investigating and analyzing the characteristics of secure transmissions in multiuser networks (e.g., the massive number of Internet of Things (IoT) devices in 6G networks). Due to the difficulty of obtaining the exact secrecy capacity region in wireless multiuser networks, several alternative methods are used to characterize the secrecy performance of multiuser networks. For example, we can analyze the secrecy sum-rate scaling in terms of the number of users based on multiuser diversity (MUD). In this paper, we propose an opportunistic user scheduling scheme that achieves optimal MUD gain, combined with a power control mechanism for reducing information leakage to multiple eavesdroppers in wireless networks. The proposed scheme considers multiuser transmissions in one scheduling time slot by adopting orthogonal random beamforming at the receiver to exploit the full degrees-of-freedom gain with an assumption that each user (or IoT device) is equipped with a single antenna, and base station and eavesdroppers have multiple antennas. The main contribution of this paper is to derive the analytic result of the achievable secrecy sum-rate scaling in a high signal-to-noise ratio (SNR) regime. We evaluate the performance of the proposed scheduling scheme with a power control mechanism through simulations with both internal and external eavesdropping scenarios. We further discuss the extensibility of our analysis to various applications such as satellite communications and IoT networks. [ABSTRACT FROM AUTHOR]

Machine learning (ML) algorithms have been widely used to improve the performance of telecommunications systems, including reconfigurable intelligent surface (RIS)-assisted wireless communication systems. The RIS can be considered a key part of the backbone of sixth-generation (6G) communication mainly due to its electromagnetic properties for controlling the propagation of the signals in the wireless channel. The ML-optimized (RIS)-assisted wireless communication systems can be an effective alternative to mitigate the degradation suffered by the signal in the wireless channel, providing significant advantages in the system's performance. However, the variety of approaches, system configurations, and channel conditions make it difficult to determine the best technique or group of techniques for effectively implementing an optimal solution. This paper presents a comprehensive review of the reported frameworks in the literature that apply ML and RISs to improve the overall performance of the wireless communication system. This paper compares the ML strategies that can be used to address the RIS-assisted system design. The systems are classified according to the ML method, the databases used, the implementation complexity, and the reported performance gains. Finally, we shed light on the challenges and opportunities in designing and implementing future RIS-assisted wireless communication systems based on ML strategies. [ABSTRACT FROM AUTHOR]

The primary focus of this paper is to evaluate the channel capacity of a Terahertz (THz) communication system using a Multiple Input Multiple Output (MIMO) technique. By deriving mathematical expressions for channel capacity and considering practical constraints, the paper provides insights into the performance of such systems under various conditions. The channel model used in this work accommodates the channel accuracies and transceivers constraints. To validate the proposed channel capacity, some simulations by taking into account deferent parameters namely SNR (Signal to Noise Ratio), MIMO channel Matrix size, and distance between transmitter and receiver are performed. These simulations are carried out for 3 cases which are: (1) Channel State Information CSI is known to both transmitter (Tx) and receiver (Rx), (2) CSI is known to Rx but unknown to Tx, (3) CSI is unknown to both Tx and Rx. In this study, we introduce a mathematical formulation for a communication channel tailored for Terahertz (THz) applications. Using this channel model, we analyze the capacity of the THz channel. The suggested research has the potential to be applied in the design and enhancement of Terahertz (THz) wireless communication systems, aiding in the advancement of robust and high-capacity wireless networks that can fulfill the requirements of contemporary multimedia applications. [ABSTRACT FROM AUTHOR]

The development of intelligent transport systems, mobile cellular networks, microwave links, and vehicle communications has accelerated with the use of wireless connections as a communication channel in 5G wireless technology. Weather, including rain, fog, snow, sand, and dust, impacts wireless communication channels in various ways. These effects are more pronounced at the high frequencies of millimeter-wave bands. Recently, the 5G network has made it possible to support a variety of applications with fast speeds and high-quality content. To facilitate the use of high-millimeter-wave frequencies, a recent study investigated how sand and dust affect the 5G communication channel. In this paper, we consider the impact of frequent and heavy rainfall on millimeter-wave propagation and cross-polarization of the wave at various points along the propagation path caused by rainfall in urban and highway scenarios in Malaysia. We estimate rainfall attenuation, path loss, and link margin at various millimeter-wave frequencies. From our simulation results, it is evident that rainfall attenuation, path loss, and link margin depend on the operating frequency, path difference, and rainfall rate. In this paper, we estimate and compare the optimal path difference values under urban and highway scenarios both with and without rainfall attenuation. [ABSTRACT FROM AUTHOR]

This Special Issue originates from the international conference 2021 Joint EuCNC & 6G Summit (Joint European Conference on Networks and Communications and 6G Summit), which was held in June 2021 in virtual format. The Technical Programme Chairs of the conference selected the best papers and invited authors to submit an extended version of their paper by at least one-third of their length. Only the top ranked papers were invited to this Special Issue, in order to fulfil its purpose. The main target was to collect and present quality research contributions in the most recent activities related to technologies, systems and networks beyond 5G. Through this Special Issue, the state-of-the-art is presented and the new challenges highlighted, regarding the latest advances on systems and network perspectives that are already being positioned beyond 5G, bridging as well with the evolution of 5G, including applications and trials. Therefore, the motivation for this Special Issue is to present the latest and finest results on the evolution of research of mobile and wireless communications, coming, but not exclusively (since Joint EuCNC & 6G Summit is a conference open to the whole research community), from projects co-financed by the European Commission within its R&D programmes. [ABSTRACT FROM AUTHOR]

The article presents a collection of six outstanding papers which were selected during the 2008 annual International Conference on Communications and Networking in China (CHINACOM). It mentioned that the conference was provided for researchers to present advances in communication network. Topics had covered from wireless communication and networking which include one such as the study by Sayed and colleagues on a busy tone based cooperative MAC protocol for wireless local area networks.

Recently, the vector dirty paper coding (DPC) achievable rate region has been shown to be the capacity region of a multiple-input multiple-output Gaussian broadcast channel (MIMO GBC). With DPC, the multiuser interference noncausally known at the transmitter can be completely removed. In this paper, we present a vector DPC structure for MIMO GBC. It is a generalization of the single antenna superposition dirty paper coding for the scalar Gaussian dirty paper problem proposed by Bennatan et al. In a theoretical random code setting, this construction is shown to be able to achieve the promised rate performance of the MIMO GBC. We also implement it with existing vector quantizer and capacity-achieving channel coding. "Combined with iterative decoding, a design example validates the effectiveness of our methods. [ABSTRACT FROM AUTHOR]

A few years back, a generic analysis approach referred to as the MGF method was introduced for the purpose of simplifying the evaluation of the performance of digital communication over fading channels. A particular case of high interest that fell under the umbrella of the methodology was the evaluation of the average error probability performance of systems that employ receive diversity to combat multipath as well as the possible inclusion of error-correcting coding/decoding for improving power efficiency. In this paper, we extend the methodology to space-time coded systems. Illustrative examples are explicitly given for space-time trellis coding. The emphasis of the paper is on the performance analysis tools and their application, as opposed to the design of the space-time codes themselves. Copyright © 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Unmanned Aerial Vehicles (UAVs) equipped with communication technologies have gained significant attention as a promising solution for providing wireless connectivity in remote, disaster-stricken areas lacking communication infrastructure. However, enabling UAVs to provide communications (e.g., UAVs acting as flying base stations) in real scenarios requires the integration of various technologies and algorithms. In particular 3D path planning algorithms are crucial in determining the optimal path free of obstacles so that UAVs in isolation or forming networks can provide wireless coverage in a specific region. Considering that most of the existing proposals in the literature only address path planning in a 2D environment, this paper systematically studies existing path-planning solutions in UAVs in a 3D environment in which optimization models (optimal and heuristics) have been applied. This paper analyzes 37 articles selected from 631 documents from a search in the Scopus database. This paper also presents an overview of UAV-enabled communications systems, the research questions, and the methodology for the systematic mapping study. In the end, this paper provides information about the objectives to be minimized or maximized, the optimization variables used, and the algorithmic strategies employed to solve the 3D path planning problem. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surface (RIS) has emerged as a promising technology to enhance the spectral efficiency of wireless communication systems. However, if there are many obstacles between the RIS and users, a single RIS may not provide sufficient performance. For this reason, a double RIS-aided communication system is proposed in this paper. However, this system also has a problem: the signal is attenuated three times due to the three channels created by the double RIS. To overcome these attenuations, an active RIS is proposed in this paper. An active RIS is almost the same as a conventional RIS, except for the included amplifier. Comprehensively, the proposed system overcomes various obstacles and attenuations. In this paper, an active RIS is applied to the second RIS. To reduce the power consumption of active elements, a partially active RIS is applied. To optimize the RIS elements, the sum of the covariance matrix is found by using channels related to each RIS, and the right singular vector is exploited using singular value decomposition for the sum of the covariance matrix. Then, the singular value of the sum of the covariance value is checked to determine which element is the active element. Simulation results show that the proposed system has better sum rate performance compared to a single RIS system. Although it has a lower sum rate performance compared to a double RIS with fully active elements, the proposed system will be more attractive in the future because it has much better energy efficiency. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth exploration of the evolution and performance analysis of Bluetooth Low Energy (BLE) 5.0 technology. Bluetooth has revolutionized wireless communication, and BLE 5.0 represents a significant advancement, promising enhanced performance, extended range, and improved interoperability. The evolution of Bluetooth from its early versions to BLE 5.0 is examined, highlighting key features and improvements in each. The architecture of BLE 5.0, including its hierarchical structure and layers, is discussed to provide insight into its design and functionality. Performance evaluations, including data transfer speeds, range capabilities, and power consumption, are conducted to assess the effectiveness of BLE 5.0 in various scenarios. Challenges such as compatibility issues with older devices and potential interference from other wireless technologies are identified, suggesting areas for further refinement and optimization. Future directions and challenges in Bluetooth technology, including advancements in data transfer speeds, range capabilities, security protocols, and energy efficiency, are also discussed. [ABSTRACT FROM AUTHOR]

With the increase in demand for high data rates and high bandwidth because of multiple users all over the globe, the technology has moved toward the next-generation of wireless communication. This rapid advancement of wireless communication technologies has led to the emergence of 5G networks, which promise significantly higher data rates, lower latency, and enhanced connectivity. Researchers believe that five essential techniques can enable 5G. Beamforming is one of those essentials, as it plays a vital role in achieving reliable and high-capacity communication. This review article portrays a comprehensive analysis of the 5G beam-former Microstrip Patch Antenna array techniques for communication systems. The paper comprises of a deep overview of the fundamental concepts and principles of beamforming, including analog, hybrid, and digital beamforming techniques. It explores the advantages and disadvantages of each approach and discusses their suitability for 5G applications. An in-depth examination of various beamforming techniques employed in 5G, encompassing traditional beamforming, massive Multiple- Input-Multiple-Output beamforming, hybrid beamforming, and adaptive beamforming. The discussion encompasses the strengths, weaknesses, and performance trade-offs of each technique, along with their applicability in diverse deployment scenarios and applications. The review of multiple couplers that are used for the feeding of the antenna is discussed with included hybrid coupler, Wilkinson power divider, branch line coupler, and butler matrix in beamformer smart antenna for 5G/6G communications. Numerous beamforming techniques are compared based on their merits, demerits, and applications. Moreover, the dielectric substrate utilized to design the beamformer was also reviewed. The findings presented in this paper serve as a valuable resource for the researcher, scholars, and engineers working in the field of 5G wireless communications and antenna designing, facilitating the development and deployment of efficient and robust beamforming solutions for future 5G networks. [ABSTRACT FROM AUTHOR]

This review presents a concise overview of RF (radio frequency) power transistor behavior models, which is crucial for optimizing RF performance in high-frequency applications like wireless communication, radar, and satellites. The paper highlights the significance of accurate modeling in understanding transistor behavior and traces the evolution of behavior modeling techniques. Different behavior modeling strategies, such as LUT (look-up table) based models, polynomial equation-based models, and machine learning based models, are discussed along with their unique characteristics and modeling challenges. The review explores the difference between behavior models and the conventional empirical or physics-based modeling approaches, addressing the challenges of the accurate characterization of transistors at high frequencies and power levels. This paper concludes with an outlook of emerging trends, such as physical models combined with behavior models, shaping the future of RF power transistor modeling for more efficient communication systems. [ABSTRACT FROM AUTHOR]

Underwater visible light communication emerges as a promising technique to enhance the capacity of underwater wireless communication networks for upcoming generation. Major technical problem with underwater visible light communication systems in motion is the pointing, acquisition, and tracking. To ease pointing, acquisition, and tracking, hence it is important to navigate optical information beam over broad range and adjust the transmitter beam divergence angle according to the link condition, which is adjusted by the Optisystem software. In this paper, performance comparison among wide range of transmittance optical beams in underwater visible light communications system for high-speed communication is presented for PIN as well as for Avalanche photodiode. The effect of using variable transmittance beam-divergence angle on the bit-error rate, signal-to-noise ratio, communication link distance is also investigated. OptiSystem and MATLAB software is used to implement the underwater visible light communication transceiver system. Finally, it is shown in the paper that in the presence of pointing errors, adaptive beam control techniques improve the performance of high-speed Underwater visible light communication system. [ABSTRACT FROM AUTHOR]

Tracking and tracing network nodes and monitoring network topology pose a huge challenge in Wireless Mesh Networks (WMNs). This becomes even more challenging in the scenario of multiple clusters, which keep performing hand-off handovers among each other for load management or link management purposes. In the dynamic and fragile WMN scenario, loss of connectivity is very common. In the case of multi-hop multi-gateway WMNs, such a scenario is very common. The architecture of the IEEE 802.11s WMN proposes a network wherein each node selects a gateway through which it routes its packets. A node selects the gateway based on its proximity in terms of the number of hop-distance and the Air Time Link Metric. Since the selection of gateway is done by a node on basis of its local information, more than often the scheduling of gateway becomes unfair. This leads to gateway congestion and a drop in the throughput of the network. In this paper, a model of a centralized gateway scheduling scheme is proposed. This paper proposes a matrix model of a clustered WMN. A well-defined gateway service set (cluster) is formed and then this is mapped onto the matrix model of the clustered WMN. In such a centralized scheme, an additional responsibility of tracking the nodes for connectivity is also addressed through this matrix model. This ensures no lost nodes or repeated nodes while the formation of clusters. Thereafter, the paper presents the process for validation of the integrity of WMN and its clusters through a mathematical model of WMN. [ABSTRACT FROM AUTHOR]

Accurate and efficient channel estimation (CE) is critical in the context of autonomous driving. This paper addresses the issue of orthogonal frequency-division multiplexing (OFDM) channel estimation in 5G communication systems by proposing a channel estimation model based on the Parrot Optimizer (PO). The model optimizes for the minimum bit error rate (BER) and the minimum mean square error (MMSE) using the Parrot Optimizer to estimate the optimal channel characteristics. Simulation experiments compared the performance of PO-CE with the Least Squares (LS) method and the MMSE method under various signal-to-noise ratios (SNR) and modulation schemes. The results demonstrate that PO-CE's performance approximates that of MMSE under high SNR conditions and significantly outperforms LS in the absence of prior information. The experiments specifically included scenarios with different modulation schemes (QPSK, 16QAM, 64QAM, and 256QAM) and pilot densities (1/3, 1/6, 1/9, and 1/12). The findings indicate that PO-CE has substantial potential for application in 5G channel estimation, offering an effective method for optimizing wireless communication systems. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surfaces (RISs), as one of the potential key technologies in sixth generation (6G) mobile communications, feature low costs, low energy consumption, and ease of deployment. In this paper, we introduce the RIS technology into the maritime wireless communication scenario, which can transform the wireless transmission environment from uncontrollable to controllable. In the considered communication model, we derive the complex channel impulse response for the RIS propagation link and non-line-of-sight propagation link, respectively. This can be used to capture the physical properties of a communication model from different perspectives. Furthermore, based on the designed communication model, we investigate the correlation properties of propagation links in the space and time domains; they are the space correlation statistics and time correlation statistics. The provided framework addresses the technical bottleneck of the existing RIS channel modeling methods that fail to balance precision and efficiency, improves the channel model matching efficiency in the design process of RIS-enabled near-field maritime communication systems, and provides technical support for the rapid development of the 6G mobile communication industry. [ABSTRACT FROM AUTHOR]

Millimeter-wave (mmWave) antenna arrays are pivotal components in modern wireless communication systems, offering high data rates and improved spectrum efficiency. However, the performance of mmWave antenna arrays can be significantly affected by structural distortions, such as mechanical deformations and environmental conditions, which may lead to deviations in beamforming characteristics and radiation patterns. In this paper, we present a comprehensive sensitivity study of mmWave antenna arrays to structural distortion, employing a coupled structural–electromagnetic statistical concept. The proposed model integrates structural analysis techniques with electromagnetic simulations to assess the impact of structural distortions on the performance of mmWave antenna arrays. In addition, the model incorporates random element positioning, making it easy to analyze radiation pattern sensitivity to structural deformation. Demonstrating the applicability of the model, a 10 × 10 microstrip patch antenna array is designed to assess the performance of the model with a random position error and saddle shape distortion. The results of the model are then compared against the acceptable results from the HFSS software (version 13.0), where a good agreement is observed between the two results. The results show the gain variation and sidelobe level under various degrees of distortion and random errors, respectively. These results provide a guide for design, deployment, and optimization of mmWave communication networks in real-world environments. In addition, the model provides valuable insights into the trade-offs between antenna performance, structural integrity, and system reliability, paving the way for more efficient and dependable mmWave communication systems in the era of 5G and beyond. [ABSTRACT FROM AUTHOR]

One of the key advantages of terahertz (THz) communication is its potential for energy efficiency, making it an attractive option for green communication systems. Coherent THz transmission technology has recently been explored in the literature. However, there exist few error performance results for such a wireless link employing coherent THz technology. In this paper, we explore a comprehensive terrestrial channel model designed for wireless line-of-sight communication using THz frequencies. The performance of coherent THz links is analyzed, and it is found to be notably affected by two significant factors, atmospheric turbulence and pointing errors. These could occur between the terahertz transmitter and receiver in terrestrial links. The exact and asymptotic solutions are derived for bit error rate and interrupt probability for binary phase-shift keying coherent THz systems, respectively, over log-normal and Gamma–Gamma turbulent channels. The asymptotic outage probability analysis is also performed. It is shown that the presented results offer a precise estimation of coherent THz transmission performance and its link budget. [ABSTRACT FROM AUTHOR]

In a number of wireless communication systems with multibeam antennas, the distance from the antenna to subscribers in different parts of the service area varies significantly. Such systems include high-altitude platform station communication systems, communication systems based on low Earth orbit and medium Earth orbit satellites, and several others. If such a system uses an antenna with identical beams, the throughputs of communication lines in different cells can differ by more than an order of magnitude due to the variation in distance. To equalize throughputs across all cells within the service area, an antenna with different beams can be employed. The gain of these beams should be proportional to the squared slant ranges to the centers of the served cells. The gain of a beam can be modified by altering its size and shape. This paper proposes a method for service area partitioning in communication systems that accounts for the slant range to subscribers. It determines the shapes and profiles of the ideal contoured beams and presents optimized contoured beams for a real antenna. [ABSTRACT FROM AUTHOR]

The reconfigurable intelligent surfaces (RIS) represent a transformative technology in wireless communication, offering a novel approach to managing and enhancing radio signal propagation. By dynamically adjusting their electromagnetic properties, RIS can significantly improve the performance and efficiency of 5G and beyond communication systems. In this paper, we study a cognitive RIS-aided non-orthogonal multiple access (NOMA) network that serves multiple users and improves spectrum efficiency. Our analysis assumes a secondary network operates under multi-primary user constraints and interference from the primary source. We derive approximation closed-form formulas for outage probability (OP), and system throughput. To obtain further insights, an asymptotic expression for OP is computed by taking into account two power configurations at the source. Additionally, numerical results show the effects of important factors on performance, confirming the accuracy of the theoretical derivation. According to the simulation results, performance by the system under consideration might be improved considerably by combining a RIS and NOMA, particularly when compared to an orthogonal multiple access scheme. [ABSTRACT FROM AUTHOR]

Optical wireless technologies like Free Space Optics (FSO) have proven to be a perfect choice for 5G communication systems. FSO can offer low latency, high capacity, extensive connectivity, and high reliability at a low cost. However, the major limitation of FSO is its susceptibility to atmospheric turbulences, especially rain at high frequencies. In this paper, a rain efficient 10 Gbps 5G communication system using multibeam FSO and multilevel Differential Phase Shift Keying (M-ary DPSK) encoder is proposed. To evaluate the system performance at different rain intensities, the state-of-the-art Charbonneau channel model for rain attenuation has been used. The performance efficiency of the proposed system is evaluated in terms of quality factor (Q-factor), bit error rate (BER), optical signal-to-noise ratio (OSNR), and received power. The results convey that the proposed system can perform well up to 4.25 km, 3.24 km, and 2.55 km under below average, average, and above average rain conditions, respectively, with attenuation of 6.28 dB/km, 9.65 dB/km, and 19.27 dB/km, respectively. Moreover, the comparative analyses show that the proposed system performs better than the recent conventional systems in terms of bandwidth and power efficiency. [ABSTRACT FROM AUTHOR]

Several papers considered the problem of routing in ad hoc wireless networks using the positions of the mobile hosts. Perimeter routing12 gives an algorithm that guarantees delivery of messages in such networks without the use of flooding of control packets. However, this protocol is likely to fail if the transmission ranges of the mobile hosts vary because of natural or man-made obstacles. It may fail because either some connections are not considered, which effectively results in a disconnection of the network, or because some crossing connections are used, which could misdirect the message. In this paper, we describe a robust routing protocol, a variant of perimeter routing, which tolerates up to 40% of variation in the transmission ranges of the mobile hosts. More precisely, our protocol guarantees message delivery in a connected ad hoc wireless network without the use of message flooding whenever the ratio of the maximum transmission range to the minimum transmission range is at most √2. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In fact, there will have many challenges for 5G networks, towards 2030 for example, that will be progressed in B5G networks. The results show that the OTFS modulation over two-ray channels and the combination of multiple-input multiple-output systems with OTFS modulation can provide a reliable airborne communication network with low BER. In this paper, the authors consider the physical layer security (PLS) in a non-orthogonal multiple access (NOMA) relaying network with radio frequency energy harvesting (RF EH). [Extracted from the article]

With the rapid development of wireless communication technology, intelligent communication has become one of the mainstream research directions after the fifth generation (5G). In particular, deep learning has emerged as a significant artificial intelligence technology widely applied in the physical layer of wireless communication for achieving intelligent receiving processing. Channel estimation, a crucial component of physical layer communication, is essential for further information recovery. As a motivation, this paper aims to review the relevant research on applying deep learning methods in channel estimation. Firstly, this paper briefly introduces the conventional channel estimation methods and then analyzes their respective merits and drawbacks. Subsequently, this paper introduces several common types of neural networks and describes the application of deep learning in channel estimation according to data-driven and model-driven approaches, respectively. Then, this paper extends to emerging communication scenarios and discusses the existing research on channel estimation based on deep learning for reconfigurable intelligent surface (RIS)-aided communication systems. Finally, to meet the demands of next-generation wireless communication, challenges and future research trends in deep-learning-based channel estimation are discussed. [ABSTRACT FROM AUTHOR]

Filter bank multicarrier (FBMC) is a new waveform candidate in the visible light communication system (VLC). FBMC is a particular sort of multi-carrier modulation that can be viewed as an option in contrast to orthogonal frequency division multicarrier (OFDM) with CP (cyclic prefix). The point is to defeat some innate disadvantages of the normally utilized optical OFDM schemes. The principles of key transceiver should be intended to suit the necessities of the channel of IM/DD. Peak to average power ratio (PAPR) and bit error rate (BER) performance of FBMC based VLC are discussed and compared with scheme of optical OFDM. FBMC based VLC system with clipping technique has the lowest PAPR and good BER performance compared to conventional system in this paper. This paper recommends that FBMC based VLC has an incredible potential for optical wireless communication systems with high-speed. Matlab program simulations confirm the analysis. The results may shed light into potential research line on FBMC based VLC systems. [ABSTRACT FROM AUTHOR]

As a novel approach to enhance information security, physical-layer key generation is based on the channel reciprocity and spatial decorrelation of the wireless channels between two legitimate sides. Due to the half-duplex mode of communication systems, the channel responses detected by the two sides are not exactly reciprocal. Also, the eavesdropper may be extremely close to the legitimate side, and information leakage could arise due to the spatial correlation in this case. To solve this problem, this paper proposes an efficient physical-layer key generation scheme based on the combination of an autoencoder and Domain-Adversarial Training of Neural Networks (DANN), i.e., Domain-Adversarial Training of Autoencoder (DAAE). DAAE extracts the reciprocal channel features of the legitimate sides while maximizing the feature difference on the eavesdropper. Simulation experiments are conducted to verify the effectiveness of DAAE, and the experimental results show that based on DAAE, the correlation of extracted features between the eavesdropper and its adjacent node is weakened without significant influence on the legitimate sides. Meanwhile, after quantization, the primary key shows a good consistency rate and randomness. The proposed method has a good potential for industrial applications. [ABSTRACT FROM AUTHOR]

This paper proposes a MAC protocol for ad hoc networks using In-band Full-duplex (IBFD) wireless communications, which are named as AdHoc-FDMAC. To utilize IBFD communications in ad hoc networks, this protocol modifies a number of control frames in the IEEE 802.11 Distributed Coordination Function (DCF) MAC standard. Here, the detailed time sequences for all types of IBFD communications are shown for the data transmission and routing. In this paper, the probability and throughput equations for IBFD communications in different situations have been derived. The performance of the proposed AdHoc-FDMAC has been analysed in terms of probability, throughput, and routing time. The Maximum throughput of AdHoc-FDMAC has been found to be 48.34 Mbps, and it is compared with a recently published ad hoc MAC as well as with the conventional HD MAC. The AdHoc-FDMAC outperforms the recently published ad hoc MAC and conventional HD MAC by 16.80% and 66.50% throughput gain, respectively. AdHoc-FDMAC incorporates the existing Ad hoc On-demand Distance Vector (AODV) routing protocol, but this AODV routing is utilized here using IBFD communications. This paper also compares the routing time of the IBFD-based AODV with the conventional AODV. The result shows that the IBFD-based AODV requires 33.33% less routing time than that of the conventional AODV for 3-hop distance between the transmitter and receiver. This paper suggests that the AdHoc-FDMAC protocol provides much more throughput in ad hoc networks by utilizing IBFD communications. [ABSTRACT FROM AUTHOR]

The reconfiguration of wireless channels with reconfigurable reflecting surface (RIS) technology offers new design options for future wireless networks. Due to its high altitude and increased probability of establishing line-of-sight linkages with ground source/destination nodes, aerial RIS (ARIS) has greater deployment flexibility than traditional terrestrial RIS. It also provides a wider-view signal reflection. To leverage the advantages of ARIS-enabled systems, this paper defines air-to-ground linkages via Nakagami-m small-scale fading and inverse-Gamma large-scale shadowing, considering realistic composite fading channels. To construct a tight approximate closed-form formula for the outage probability (OP), a new mathematical framework is proposed. Additionally, a deep-learning-based system called the BiLSTM model is deployed to evaluate OP performance in the 3D spatial movement of the ARIS system. In the offline phase, the proposed model is trained with real-value channel state estimation sets and enhances OP performance in the online phase by learning channel information in a bidirectional manner. Simulation results demonstrate that the proposed BiLSTM model outperforms all other models in analyzing OP for the ARIS system. [ABSTRACT FROM AUTHOR]

The need for faster and more dependable wireless communication networks has encouraged the development of 6G networks. This article explores the integration of Mobile Edge Computing (MEC) cloud architectures and the potential of self-driving Vehicle-to-Everything (V2X) communication to achieve ultra-low latency and high dependability in 6G networks. By integrating MEC into the 6G network fabric, latency is reduced by bringing data processing closer to end-users, particularly vehicles, thus enhancing computational capabilities at the network's edge. The fusion of MEC with self-driving V2X communication holds the key to realizing the potential of 6G networks, enabling seamless communication among vehicles, roadside infrastructure, and individuals. Extensive testing and simulations predict that the 6G network's latency for User Equipments (UEs) will fall within an impressive range of 4ms to 10ms, unlocking new opportunities for mission-critical services, augmented reality, and real-time applications. The paper substantiates the dependability of 6G networks under various scenarios, ensuring a stable and reliable communication infrastructure. The objectives of the study are twofold: firstly, to evaluate the potential of MEC integration in 6G networks and its impact on reducing latency for end-users, particularly in the context of self-driving V2X communication; and secondly, to predict and verify the ultra-low latency capabilities of 6G networks for UEs through extensive testing and simulations, thereby enabling new opportunities for mission-critical services, augmented reality, and real-time applications. The real network simulation carried in the MATLAB environment shows that for UEs in the 6G network, the predicted latency will be approximately 4ms to 10ms, which showcasing unprecedented opportunity of possibilities in communication and services. [ABSTRACT FROM AUTHOR]

This paper investigates the design of transmit beamforming in an integrated sensing and communication system, where an unmanned aerial vehicle (UAV) equipped with a uniform linear array (ULA) transmits combined information‐carrying and dedicated sensing signals to perform multi‐user communication and simultaneously sense potential targets. First, the transmit beamforming design is formulated as a series of non‐convex optimisation problems, and then jointly design the information and sensing beamforming to maximise the minimum communication rate under an optimised UAV deployment location, subject to the sensing beampattern gain requirements and the limited transmit power of the UAV. However, due to the application of ULA on the UAV, the formulated problems are highly non‐convex and difficult to solve optimally. To address the aforementioned issue, an efficient algorithm is proposed to find suboptimal yet high‐quality solutions. This is achieved by adopting the successive convex approximation and semidefinite relaxation. The numerical results confirm the effectiveness of the proposed algorithm and demonstrate that the transmit beamforming design achieves a balance between communication and sensing performance. [ABSTRACT FROM AUTHOR]

With increasing needs for high-bitrate, ultra-reliability, spectral efficiency, power efficiency, and reducing latency in the wireless network, global studies on the sixth generation of this network began in 2020. In this paper, we will look at intelligent reconfigurable surface structure and its application in new promising physical layer technologies, such as terahertz communications and UM-MIMO systems, to support very high-bitrate and superior network capacity in the 6G wireless communications. However, terahertz communications and UM-MIMO systems are the primary research points and confront many challenges for practical implementation. They require many RF chains and create problems in terms of cost and hardware complexity which RIS can simplify hardware and reduce cost. Therefore, we will present different modeling of wireless communication systems based on RIS for different phase information. Simulation results obtained by examining SNR performance and the error probability that shows the improvement of the received signal quality. According to results, RIS-based wireless communications can become an optimized model for future wireless communication systems. [ABSTRACT FROM AUTHOR]

In this paper, a downlink energy efficiency maximization problem is investigated in an intelligent reflective surface (IRS)-assisted visible light communication system. In order to extend wireless communication coverage of the onshore base station, an IRS mounted on a unmanned aerial vehicle (UAV) is introduced to assist an onshore lighthouse with simultaneously providing remote ship users wireless communication services and illumination. Aiming to maximizing the energy efficiency of the proposed system, a resource allocation problem is formulated as the ratio of the achievable system sum rate to the total power consumption under the constraints of the user's data requirement and transmit power budget. Due to the non-convexity of the proposed problem, the Dinkelbach method and mean-square error (MSE) method are adopted to turn the non-convex origin problem into two equivalent problems, namely transmit beamforming and reflected phase shifting. The Lagrangian method and semidefinite relaxation technique are used to obtain the closed-form solutions of these two subproblems. Accordingly, an alternative optimization-based resource allocation scheme is proposed to obtain the optimal system energy efficiency. The simulation results show that the proposed scheme performs better in terms of energy efficiency over benchmark schemes. [ABSTRACT FROM AUTHOR]

With the rapid development of Internet of Things (IoT) technology, the number of IoT users is growing year after year. IoT will become a part of our daily lives, so it is likely that the security of these devices will be an important issue in the future. Quantum computing is maturing, and the security threat associated with quantum computing will be faced in the transmissions of IoT devices, which mainly use wireless communication technologies. Therefore, to ensure the protection of transmitted data, a cryptographic algorithm that is efficient in defeating quantum computer attacks needs to be developed. In this paper, we propose a device authentication and secure communication system with post-quantum cryptography (PQC) for AIoT environments using the NTRU and Falcon signature mechanism, which can resist quantum computer attacks and be used in AIoT environments to effectively protect the confidentiality, integrity, and non-repudiation of transmitted data. We also used Raspberry Pi to simulate AIoT devices for implementation. [ABSTRACT FROM AUTHOR]

This paper investigates the potential of active reconfigurable intelligent surfaces (RIS) to enhance wireless-powered communication networks (WPCNs), addressing the evolving connectivity needs of the internet of things (IoT). Active RIS, capable of amplifying and reflecting signals, offers a solution to surpass the limitations of passive RIS, such as double-fading attenuation, aiming to significantly improve network throughput and coverage. Our research focuses on exploiting the amplification capabilities of active RIS to boost the overall network sum throughput, engaging in a comprehensive optimization of critical network parameters, including time allocation, reflection coefficients, and phase shift matrices specific to active RIS. The formulated problem is non-convex and highly complex due to the coupling of optimization variables. We employed a successive convex approximation algorithm to solve the throughput maximization problem by converting the non-convex constraints into approximated convex constraints and solving them iteratively. Through extensive simulations, we demonstrate that our active RIS-assisted network substantially outperforms networks facilitated by passive RIS, marking a significant advancement in WPCN performance. These findings underscore the potential of active RIS technology in realizing the full capabilities of IoT connectivity. [ABSTRACT FROM AUTHOR]