Search

In the new radio wireless system, use cases for automation, automotive safety and virtual reality will require transmission and reception with very high reliability and very low latency. Radio channel fading and the onset of strong interference combine to make this task hard, which require new methods for mitigation. The alternative studied in this article is to introduce fast signal to interference and noise ratio (SINR) feedback control supported by feed‐forward control from interference estimates, thereby improving the robustness of the networked loop. This challenging nonlinear networked control problem involves delay and coarse control signal quantization. To guarantee that the deployed feedback loop instances are always well‐behaved, the SINR feedback controller is designed to be globally ℒ2$$ {\mathcal{L}}_2 $$‐stable using a new loop gain—loop delay product condition, derived from the classical circle criterion. Monte‐Carlo simulations show that the proposed controller is able to reduce the SINR back‐off significantly. [ABSTRACT FROM AUTHOR]

Channel modeling is a first step towards the successful projecting of any wireless communication system. Hence, in this paper, we analyze the performance at the output of a multi-branch selection combining (SC) diversity receiver in a wireless environment that has been distracted by fading and co-channel interference (CCI), whereby the fading is modelled by newer Beaulieu-Xie (BX) distribution, and the CCI is modelled by the κ-µ distribution. The BX distribution provides the ability to include in consideration any number of line-of-sight (LOS) useful signal components and non-LOS (NLOS) useful signal components. This distribution contains characteristics of some other fading models thanks to its flexible fading parameters, which also applies to the κ-µ distribution. We derived here the expressions for the probability density function (PDF) and cumulative distribution function (CDF) for the output signal-to-co-channel interference ratio (SIR). After that, other performances are obtained, namely: outage probability (Pout), channel capacity (CC), moment-generating function (MGF), average bit error probability (ABEP), level crossing rate (LCR), and average fade duration (AFD). Numerical results are presented in several graphs versus the SIR for different values of fading and CCI parameters, as well as the number of input branches in the SC receiver. Then, the impact of parameters on all performance is checked. From our numerical results, it is possible to directly obtain the performance for all derived and displayed quantities for cases of previously known distributions of fading and CCI by inserting the appropriate parameter values. In the second part of the paper, a workflow for automated network experimentation relying on the synergy of Large Language Models (LLMs) and model-driven engineering (MDE) is presented, while the previously derived expressions are used for evaluation. Due to the aforementioned, the biggest value of the obtained results is the applicability to the cases of a large number of other distributions for fading and CCI by replacing the corresponding parameters in the formulas for the respective performances. [ABSTRACT FROM AUTHOR]

The purpose of this work is to perform the generalized secrecy capacity (i.e., secrecy rate and secrecy outage capacity) analysis of the scheduled transmit antenna selection scheme over non-identical Nakagami fading channels. Especially, this work considers maximal ratio combining (MRC) and selection combining (SC) at the authorized receiver and eavesdropper. To derive the secrecy capacity, this work derives accurate and asymptotic distribution functions (i.e., probability density function and cumulative distribution function) of the received signal to noise ratio (SNR) of the proposed scheme using MRC and SC receivers over non-identical Nakagami fading channels. Using the accurate distribution functions, this work derives the accurate average secrecy rate and tight average secrecy outage capacity of the proposed scheme for various combining scenarios over non-identical Nakagami fading channels. Using the asymptotic distribution functions, this work derives the asymptotic average secrecy capacity and quantifies the high SNR slope and the high SNR power offset for the average secrecy capacity over non-identical Nakagami fading channels. From numerical results, this work shows that the high SNR slope for the average secrecy capacity is one regardless of combining type. It means that neither the authorized parameters nor the eavesdropper parameters affect the high SNR slope over non-identical Nakagami fading channels. On the contrary, the high SNR power offset improves proportionally to the authorized parameters and inversely proportional to the eavesdropper parameters over non-identical Nakagami fading channels. [ABSTRACT FROM AUTHOR]

A nonlinear system, exhibiting a unique asymptotic behaviour, while being continuously subject to a stimulus from a certain class, is said to suffer from fading memory. This interesting phenomenon was first uncovered in a non-volatile tantalum oxide-based memristor from Hewlett Packard Labs back in 2016 out of a deep numerical investigation of a predictive mathematical description, known as the Strachan model, later corroborated by experimental validation. It was then found out that fading memory is ubiquitous in non-volatile resistance switching memories. A nonlinear system may however also exhibit a local form of fading memory, in case, under an excitation from a given family, it may approach one of a number of distinct attractors, depending upon the initial condition. A recent bifurcation study of the Strachan model revealed how, under specific train stimuli, composed of two square pulses of opposite polarity per cycle, the simplest form of local fading memory affects the transient dynamics of the aforementioned Resistive Random Access Memory cell, which, would asymptotically act as a bistable oscillator. In this manuscript we propose an analytical methodology, based on the application of analysis tools from Nonlinear System Theory to the Strachan model, to craft the properties of a generalised pulse train stimulus in such a way to induce the emergence of complex local fading memory effects in the nano-device, which would consequently display an interesting tuneable multistable oscillatory response, around desired resistance states. The last part of the manuscript discusses a case study, shedding light on a potential application of the local history erase effects, induced in the device via pulse train stimulation, for compensating the unwanted yet unavoidable drifts in its resistance state under power off conditions. [ABSTRACT FROM AUTHOR]

Predicting the remaining useful life (RUL) of lithium-ion (Li-ion) batteries is crucial to preventing system failures and enhancing operational performance. Knowing the RUL of a battery enables one to perform preventative maintenance or replace the battery before its useful life expires, which is vital in safety-critical applications. The prediction of the RUL of Li-ion batteries plays a critical role in their optimal utilization throughout their lifetime and supporting sustainable practices. This paper conducts a comparative analysis to assess the effectiveness of multiple machine learning (ML) models in predicting the capacity fade and RUL of Li-ion batteries. Three case studies are analyzed to assess the performances of the state-of-the-art ML models, considering two distinct datasets. These case studies are conducted under various operating conditions such as temperature, C-rate, state of charge (SOC), and depth of discharge (DOD) of the batteries in Cases 1 and 2, and a different set of features and charging policies for the second dataset in Case 3. Meanwhile, diverse extracted features from the initial cycles of the second dataset are considered in Case 3 to predict the RUL of Li-ion batteries in all cycles. In addition, a multi-feature multi-target (MFMT) feature mapping is introduced to investigate the performance of the developed ML models in predicting the battery capacity fade and RUL in the entire life cycle. Multiple ML models that are developed for the comparison analysis in the proposed methodology include Random Forest (RF), extreme gradient boosting (XGBoost), light gradient-boosting machine (LightGBM), multi-layer perceptron (MLP), long short-term memory (LSTM), and attention-LSTM. Furthermore, hyperparameter tuning is applied to improve the performance of the XGBoost and LightGBM models. The results demonstrate that the extreme gradient boosting with hyperparameter tuning (XGBoost-HT) model outperforms the other ML models in terms of the root-mean-squared error (RMSE) and mean absolute percentage error (MAPE) of the battery capacity fade and RUL for all cycles. The obtained RMSE and MAPE values for XGBoost-HT in terms of cycle life are 69 cycles and 6.5%, respectively, for the third case. In addition, the XGBoost-HT model handles the MFMT feature mapping within an acceptable range of RMSE and MAPE, compared to the rest of the developed ML models and similar benchmarks. [ABSTRACT FROM AUTHOR]

The two-sided bimodality property of Alternate Rician Shadowed (ARS) fading channels makes it a suitable fading model for body-centric wireless communication. The ARS fading model consists of two fluctuating specular components in which only one is active at a time. To provide excellent spectral efficiency with higher quality of service, system transmitter employs an adaptive transmission scheme. This paper derives the exact closed-form expressions of the ARS fading channels capacity. Various adaptive transmission schemes such as channel inversion with a fixed-rate, truncated channel inversion with a fixed-rate, and optimal rate adaptation are considered. A comparison of these schemes is also highlighted. Performance expressions such as binary bit error rate for various coherent and non-coherent modulation schemes and the outage probability are also derived. The derived results are plotted and analyzed for varying fading parameters of the ARS channel. Finally, the results of all performance metrics are verified with Monte-Carlo simulation results. [ABSTRACT FROM AUTHOR]

In this paper, we study an uplink power-domain non-orthogonal multiple access (PD-NOMA) system, in which 2K+1 users are served. The user clustering process based on High-High/High-Low algorithm precedes the utilization of the data-rate based power allocation algorithm. Channels are characterized by Fisher-Snedecor composite fading model interpreted as model with a high level of generality. The influence of different fading/shadowing channel conditions, number of users and their positions is portrayed through the numerical results of data sum rate of the studied PD-NOMA system. [ABSTRACT FROM AUTHOR]

The capture effect is a frequently observed phenomenon in vehicular ad hoc networks (VANETs) communication. When conflicts arise during time slot access, failure to access does not necessarily occur; instead, successful access may still be achieved. The capture effect can enhance the likelihood of multiple access and improve communication efficiency. The security of VANETs communication is undoubtedly the primary concern. One crucial approach to enhance security involves the design of an efficient and reliable medium access control (MAC) protocol. Taking into account both aspects, we propose a novel framed slotted Aloha (FSA) MAC protocol model. Firstly, we derive the closed-form expression for the capture probability in the Rician fading channel in this paper. Subsequently, we analyze how the number of vehicles and time slots influence the success probability of vehicle access channels as well as examine the impact of the capture effect on this success probability. Then, under constraints regarding vehicle access channel success probability, we derive optimal values for slot numbers, access times, and transmission power while proposing a comprehensive implementation method to ensure high access channel success probabilities. We verify both theoretical derivations and proposed methods through simulation experiments. [ABSTRACT FROM AUTHOR]

Summary: In this paper, the massive multiple‐input multiple‐output fractional Fourier transform‐based orthogonal frequency division multiplexing (MIMO FrFT‐OFDM) system is investigated using the Long Range (LoRa) modulation technique. The conventional system relies on quadrature amplitude modulated (QAM) modulation technology; high‐power amplifiers are needed to transmit the QAM signal. The LoRa modulation technique produces long‐range and low power signals. The two‐wave with diffused power (TWDP) fading channel is used to examine the system's performance. The expression of the bit‐error rate (BER) of the proposed system is also represented in a unique closed form. The proposed system is applied to a state‐of‐the art hospital, one of the Internet of Things (IoT) applications. As the problem of heart stroke is common, it needs to be monitored every second. The electrocardiogram (ECG) data are used to evaluate how well the proposed system is working. Using the proposed model, the physicians get the patient's ECG data while moving in the hospital, getting it at a high data rate, at a low cost because of the extended battery life, a long range, and a low BER. The data considered are from the MIT‐BIH Arrhythmia Database. The result displays that the proposed model achieves a BER of 0.0005 at 10 dB of signal‐to‐noise ratio (SNR), and the conventional model achieves the same BER at 15 dB of SNR. The BER performance of the proposed system is improved by nearly 5 dB. [ABSTRACT FROM AUTHOR]

Summary: Distributed multitask learning over adaptive networks with non‐ideal links is studied in this paper. The performance of an adaptive multitask network with wireless communication links suffering from flat fading and additive white Gaussian noise is derived through simulation and theoretical analysis. The effect of the wireless link on the learning performance of a multitask network is analyzed. It is shown that this destroying effect is reduced by using local equalizers at each agent along with the intelligent cooperation policy based on the correntropy criterion. Stability condition, steady‐state and transient performances are studied theoretically. Finally, the theoretical results are validated by numerical simulations and computer experiments. [ABSTRACT FROM AUTHOR]

Non-orthogonal multiple access (NOMA) has been envisaged as a key driving scheme for future wireless communication systems because of its huge connecting ability and superior spectrum efficiency. Integrating the concepts of Multiple-input-multiple-output (MIMO) into NOMA enhance the system capacity at the cost of hardware complexity. In this article, we consider an MIMO-NOMA-based system in which the users are partitioned to form a cluster. A beamforming vector that helps to maximize the channel gain has been designed to remove the inter-cluster interference. This work presents the effect of user pairing in downlink MIMO-NOMA systems. User pairing has a significant impact on the performance of MIMO-NOMA systems. Outage probability and Ergodic Capacity (EC) are analyzed for MIMO-NOMA systems. Exact outage probability expressions are provided for user pairing to reveal some useful insights that pairing two users with dissimilar channel conditions increases the probability that NOMA achieves a larger sum rate than traditional orthogonal multiple access (OMA) systems. This mathematical investigation is carried out by considering Nakagami-m fading channel. Furthermore, this notion of user pairing is presented for imperfect successive interference cancellation (SIC). Diversity order is also derived for the strong and weak users. Extensive simulation results are provided to validate the derived analytic expressions. Furthermore, it is also demonstrated that the EC of MIMO-NOMA systems is improved significantly when compared with traditional OMA systems. [ABSTRACT FROM AUTHOR]

The recent developments in unmanned aerial vehicles (UAVs) and indoor hybrid LiFi–WiFi networks (HLWNs) present a significant opportunity for creating low-cost, power-efficient, reliable, flexible, and ad-hoc HLWN-enabled indoor flying networks (IFNs). However, to efficiently operate and practically realize indoor HLWN, a unified physical layer (UniPHY) is indispensable for joint communication (control and data transfer) and sensing (e.g., localization). A UniPHY structure reduces costs and increases overall flexibility for HLWN-based IFNs. While conventional block-based wireless transceivers independently designed for LiFi and WiFi offer mediocre performance for a composite UniPHY waveform, a machine learning-based end-to-end learning framework for UniPHY can improve overall error performance and reduce the complexity of UAV transceiver hardware. Therefore, this paper proposes a novel generic end-to-end learning framework for a UniPHY system that can efficiently enable HLWN. The performance of the proposed learning framework based on deep neural networks (DNNs) and convolutional neural networks (CNNs) is investigated. Additionally, we assess the computational complexity of the proposed DNN and CNN learning frameworks. The results demonstrate that the performance of DNNs and CNNs varies depending on the considered channel model. Specifically, the analysis reveals that CNNs outperform traditional DNNs in WiFi (Rayleigh fading-based) channels. In contrast, traditional DNNs perform better than CNNs in LiFi (additive white Gaussian noise (AWGN)-based) channels. [ABSTRACT FROM AUTHOR]

A new composite model called shadowed Beaulieu-Xie (BX) is used in terahertz and millimeter-wave wireless communication systems. This model characterizes an environment with an arbitrary number of non-line-of-sight and line-of-sight signals. In this paper, an analysis of the average bit error rate (ABER) is done. The analysis is carried out for different coherent and non-coherent modulation techniques. The mathematical expressions of ABER are obtained using the probability density function of the output signal to noise ratio of the shadowed BX fading channel. A new closed-form ABER expression for gray-coded rectangular quadrature amplitude modulation over the shadowed BX channel is also evaluated. The effects of fading and shadowing parameters on the modulation techniques are analyzed and compared. [ABSTRACT FROM AUTHOR]

By reducing the transmitting power at the base station and expanding the coverage range of wireless communication, cooperative communication has turned into a higher imperative. This article evaluates the outage probability, average symbol error rate (ASER) for coherent as well as noncoherent modulation pattern, ergodic capacity and throughput of a multihop communication technique over the Fisher-Snedecor F fading channels. The multihop transmission scheme utilises a source, a set of relays and the destination node. The intervening relays of the system are regenerative with decode and forward type. Each hop of the system undergoes Fisher-Snedecor F fading channels. The MGF-based approach is used to derive the ASER of the system. The outage probability and ASER performance upgrade with the advancement of fading parameter as well as shadowing parameter of the channel. The ergodic capacity decreases with the improvement in shadowing parameter and the number of hops. The throughput of the system rises in connection with the reduction of total hops. Simulations validate the correctness of the numerically appraised results. [ABSTRACT FROM AUTHOR]

Apart from supporting the essential requirements of low power consumption in the IoT networks, Long Range (LoRa) technology provides wide-area coverage, and massive scalability at a low cost. The conventional LoRa network follows a single-hop approach, which may lead to greater path loss and rapid battery depletion thereby rendering low coverage and connectivity. In this work, a dual-hop LoRa technology incorporating cooperative communication is presented and a mathematical framework has been formulated in terms of received power and signal-to-noise ratio (SNR). Further, outage probability, spectral efficiency and throughput are computed under the Rayleigh fading channel to explore the proposed LoRa network performance. A critical comparative analysis of the dual-hop LoRa network with the conventional single-hop LoRa network has been done. Evaluation reveals 75%, 62% and 70% improvement in the outage probability, spectral efficiency and throughput respectively by incorporating a cooperative scenario in the LoRa network. In addition, to enhance the performance of the LoRa nodes in both cooperative as well as non-cooperative scenarios, a metaheuristic optimization approach known as the whale optimization algorithm (WOA) is utilized. Based on the mathematical model, an optimization problem is defined whose solution gives the optimal transmission parameters to maximize the received power. The performance metrics evaluated utilizing the optimized solution discovered using WOA demonstrate the improved performance of the LoRa nodes in both the cooperative as well as non-cooperative scenarios. [ABSTRACT FROM AUTHOR]

In this paper, a novel downlink cooperative non-orthogonal multiple access scheme (C-NOMA) is proposed with various receiver diversity combiner techniques, such as maximal-ratio-combiner, equal gain combiner and selection combiner technique over η - μ fading channel. In addition, a user pairing is deployed for the proposed system model to reduce system complexity. To be more specific, to serve NOMA scheme, two users are selected out of multiple users in the proposed system model. The mathematical expressions of outage probability (OP) for the selected users are derived with M branch diversity combiner over η - μ fading channel, thereby the outage of the user pairing is obtained and analysed. Furthermore, the impact of various parameters such as number of receiver antennas M , user pairing, imperfect successive interference cancellation and target rate of users γ th , on OP are examined. From the analytical and simulation results it is evident that the proposed system outperforms the C-OMA system. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel method for a tighter approximation of the Q -function using the two-point Gauss quadrature rule. In the proposed method, the integral used for approximation can be divided into any number of sub-intervals and result in an approximated expression, which is a simple summation of exponentials. The proposed approximation provides lesser relative error not only at smaller but also at larger arguments of Q -function. As an application, the proposed approximation of the Q -function can be efficiently used to evaluate the closed-form expressions of symbol error probability (SEP) for various modulation techniques over generalized fading channels. In order to show the applicability and tightness of the proposed approximation, we have derived more accurate approximated expressions for binary phase shift keying (BPSK) and triangular quadrature amplitude modulation (TQAM) schemes over α–κ–μ fading channel. The results indicate a comparison between the proposed approximation and existing approximations while demonstrating improved accuracy in terms of the relative error and hence achieve a tighter bound while calculating the error performance of the digital modulation schemes at both lower and higher values of SNRs. The accuracy of the proposed work is also verified by analytical and Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

Lamb and Rayleigh waves-based dispersion analysis has been carried out for non-destructive surface wave testing of different slab-like structures involving a concrete roof slab, a concrete floor, a concrete pavement, and an asphaltic pavement. An impact was generated by gently striking the slab's free surface with a hammer. A method has also been given to generate the governing (predominant) dispersion mode in the case of Rayleigh wave propagation considering the complex nature of the dispersion function $\vert {{ D}\lpar {c\comma \; \kappa } \rpar } \vert$ | D (c , κ) | ; $c$ c and $\kappa$ κ refer to phase velocity and wavenumber, respectively. The theoretical dispersion plots generated from the inversion analysis by varying the values of different input parameters were subsequently closely matched with the corresponding obtained field dispersion images for different cases in order to back compute the elastic profile of the slab/pavement. For developing the dispersion images, the Park's wavefield transformation method was employed. For checking the thicknesses of the different layers, cylindrical cores were also extracted. The study is expected to be useful for evaluating different slab-like structures, including pavements, by using surface wave-based non-destructive tests. [ABSTRACT FROM AUTHOR]

Summary: Different from the prior works, this paper presents the performance analysis of an intelligent reflecting surface (IRS)‐assisted communication link in a static and mobile scenario impaired by Rayleigh fading and additive white generalized Gaussian noise (AWGGN). Precisely, the IRS is configured as an intelligent access point, and the mobile behavior of the nodes is characterized by the random waypoint (RWP) model. To this end, closed‐form expressions of average bit error rate (BER), average channel capacity (ACC), and outage probability (OP) in both static and mobile scenarios are obtained. To gain further insight into the system performance at high signal‐to‐noise ratio (SNR), asymptotic expressions are obtained. Moreover, the effect of the number of reflective elements (N) and the shaping parameter (λ) on the system performance is thoroughly studied. The results indicate that introduction of IRS leads to significant improvement in the overall system performance. The derived results are corroborated with Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

The current paper studies comprehensive analysis of various cooperative spectrum sensing (CSS) schemes in generalized $ \kappa -\mu $ κ − μ fading environment. More precisely, the optimization of several network parameters as well as throughput performance analysis of various CSS schemes are studied. In each CSS scheme, every cognitive radio user (CRU) first senses and receives the primary user (PU) signal using sensing channels, performs an energy detection (ED) operation. Depending upon the type of the scheme, CRU makes and forwards its local binary decision or simply forwards its data to the fusion center (FC) with the help of reporting channels. Then FC implements any one of the CSS schemes for making a final decision about busy or free status on PU. The novel expressions for missed and false detection probabilities subject to CSS scheme under fading are developed. The performance of several decision and data CSS schemes through total error rate, considering different network and $ \kappa -\mu $ κ − μ fading parameters is investigated. The impact of erroneous channel conditions on each CSS scheme is investigated. The expressions for optimal system parameters of decision-based CSS schemes under fading are developed and optimal values for different network conditions are estimated. Further, the throughput performance of decision-based CSS schemes for different networks and $ \kappa -\mu $ κ − μ fading parameters values is studied. [ABSTRACT FROM AUTHOR]

Calculations of angles between magnetic moments and rotation axes have been carried out for radio pulsars located at different distances from the "death line." We have shown that these angles decrease from 36° to 10° when pulsars move to the "death line". Such values correspond to kinematic ages from 1 to 10 millions of years. We also argue that radio luminosities of pulsars decrease for these ages. This means that radio pulsars fade out when their age increases. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) is a new para-digm for achieving ubiquitous connectivity by enormously deploying physical objects like sensors, actuators, and controllers. Wireless communication is one of the main enabling technologies that make the IoT a reality. However, due to the open nature of wireless communication and constraints on energy consumption, this raises concerns about the security of the IoT. Eavesdropping is a major threat to the wireless communications security. To counteract such an attack, physical layer security is among the promising solutions. The aim of this work is to evaluate the secrecy performance of two-hop wireless communication systems. This evaluation is done in the presence of potential eavesdropping threats over Nakagami-m and mixed Rayleigh–Nakagami-m fading channels. To enhance the security of the system, the use of cooperative jamming and opportunistic relaying has been considered. In particular, based on classical probability theory, we first analyze the secrecy outage performance for scenario 1, where all channels (S-R, R-D, R-R, S-E, R-E) experience Nakagami-m fading. Then, we examine the secrecy performance for scenario 2, where the channel coefficients for links (S-R, R-D, S-E, R-E) are subject to Nakagami-m fading and the channel coefficients for the link (R-R) follow Rayleigh fading. Finally, simulation and numerical results are presented to validate our theoretical achievements. The results suggest that as the fading parameter m increases, the probability of secrecy outages decreases, leading to an improvement in the security performance of the wireless IoT data collection process. [ABSTRACT FROM AUTHOR]

Lamb and Rayleigh waves-based dispersion analysis has been carried out for non-destructive surface wave testing of different slab-like structures involving a concrete roof slab, a concrete floor, a concrete pavement, and an asphaltic pavement. An impact was generated by gently striking the slab's free surface with a hammer. A method has also been given to generate the governing (predominant) dispersion mode in the case of Rayleigh wave propagation considering the complex nature of the dispersion function $\vert {{ D}\lpar {c\comma \; \kappa } \rpar } \vert$ | D (c , κ) | ; $c$ c and $\kappa$ κ refer to phase velocity and wavenumber, respectively. The theoretical dispersion plots generated from the inversion analysis by varying the values of different input parameters were subsequently closely matched with the corresponding obtained field dispersion images for different cases in order to back compute the elastic profile of the slab/pavement. For developing the dispersion images, the Park's wavefield transformation method was employed. For checking the thicknesses of the different layers, cylindrical cores were also extracted. The study is expected to be useful for evaluating different slab-like structures, including pavements, by using surface wave-based non-destructive tests. [ABSTRACT FROM AUTHOR]

This paper investigates the power allocation in a massive multiple‐input multiple‐output (MIMO) downlink system, where the base station (BS) simultaneously transmits information and energy to information terminals and energy terminals without resorting to any wireless energy harvesting (EH) protocol, respectively. First, with respect to this system, the closed‐form expressions of achievable rate and harvested energy are, respectively, derived for Rayleigh fading channels. Then, from these expressions, three optimization problems are formulated based on quality‐of‐service (QoS) requirements, with the purposes of maximizing achievable sum rate, harvested sum energy and joint QoS requirements, respectively. The optimization problem of maximizing achievable sum rate is transformed into a sequence of geometric programmings (GPs), which can be solved efficiently with standard convex optimization tools. The optimization problem of maximizing harvested sum energy is proved to be solvable as a linear program. The optimization problem of maximizing joint QoS requirements is shown to be a multi‐objective optimization problem (MOOP) and solved by a one‐dimensional search based on GP. Finally, numerical results manifest that the proposed power allocation algorithms can provide good system performances of achievable sum rate and harvested sum energy, and jointly guarantee QoS fairness in terms of achievable rate and harvested energy. [ABSTRACT FROM AUTHOR]

With the progress of communication technology, the increasing wireless devices are hooked up the networks, and the consequent security problems cannot be ignored. At present, the solutions mainly include secret key system and physical layer security (PLS). However, secret key system that relies on highly complex algorithms for encryption and decryption still has the risk of being cracked by powerful computers. In this paper, the PLS of Beaulieu‐Xie fading channels is studied. To improve the transmission quality and support higher speed data transmission, the single‐input multiple‐out (SIMO) system considered is the Wyner eavesdropper model with decoding and forwarding (DF) relay over Beaulieu‐Xie fading. The closed‐form theoretical formulas for secure outage probability (SOP) and strictly positive secrecy capacity (SPSC) are obtained by complex unified functional representation, which includes two cases: LRD≤LRE${L_{RD}} \le {L_{RE}}$ and LRD>LRE${L_{RD}} > {L_{RE}}$. Moreover, the theoretical formulas are verified by Monte Carlo results. By comparing the simulation results with the theoretical analysis, the authors discussed the factors to improve the secure performance. Experiments show that the larger ratio of (λRD,λRE)$({{\lambda _{RD}},{\lambda _{RE}}})$, the smaller ratio of (mRD,mRE)$({{m_{RD}},{m_{RE}}})$, smaller signal‐to‐noise ratio (SNR) of eavesdropping channels, smaller threshold Cth${C_{th}}$ and more legitimate antennas LRD${L_{RD}}$ are beneficial to the improvement of anti‐interference capability for the relay networks with Beaulieu‐Xie distributions when the legal channel link R→D is in a state of high SNR. [ABSTRACT FROM AUTHOR]

This paper investigates intelligent reconfigurable surface‐assisted non‐orthogonal multiple access (NOMA) networks for short packet communications where the source with multiple antennas utilizes beamforming technology to serve two end users including a near user and a far user. The analysis system, closed‐form expressions of the average block error rates (BLERs), latency and reliability at all users are derived under assuming perfect channel state information over quasi‐static Rayleigh fading channels. For evaluating the improvement of the network system, a deep neural network (DNN) framework is designed to predict the performance parameters in two cases: (i) BLERs prediction of the users, (ii) transmit power allocation under the constraints of BLERs at each user which satisfy the extremely high reliability requirements of uRLLCs. The extensive results demonstrate that first, the DNN‐based estimation results are more accurate than Monte‐Carlo simulation results with low execution time. Second, the allocated power for each user can be accurately predicted at the high layers. Finally, two methods of evaluating the effectiveness of the DNN model, i.e. root mean square error and mean absolute percentage error, reach low error which verify the power of the designed DNN model for future analysis. [ABSTRACT FROM AUTHOR]

Over the past two decades, numerous research projects have concentrated on cognitive radio wireless sensor networks (CR-WSNs) and their benefits. To tackle the problem of energy and spectrum shortfall in CR-WSNs, this research proposes an underpinning decode-&-forward (DF) relaying technique. Using the suggested time-slot architecture (TSA), this technique harvests energy from a multi-antenna power beam (PB) and delivers source information to the target utilizing energy-constrained secondary source and relay nodes. The study considers three proposed relay selection schemes: enhanced hybrid partial relay selection (E-HPRS), conventional opportunistic relay selection (C-ORS), and leading opportunistic relay selection (L-ORS). We present evidence for the sustainability of the suggested methods by examining the outage probability (OP) and throughput (TPT) under multiple primary users (PUs). These systems leverage time switching (TS) receiver design to increase end-to-end performance while taking into account the maximum interference constraint and transceiver hardware inadequacies. In order to assess the efficacy of the proposed methods, we derive the exact and asymptotic closed-form equations for OP and TPT & develop an understanding to learn how they affect the overall performance all across the Rayleigh fading channel. The results show that OP of the L-ORS protocol is 16% better than C-ORS and 75% better than E-HPRS in terms of transmitting SNR. The OP of L-ORS is 30% better than C-ORS and 55% better than E-HPRS in terms of hardware inadequacies at the destination. The L-ORS technique outperforms C-ORS and E-HPRS in terms of TPT by 4% and 11%, respectively. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we have presented the outage probability analysis of multiple intelligent reflecting surface (IRS)‐assisted single‐input‐single‐output (SISO) system with switched diversity schemes. The switched diversity is simpler than the selection combining diversity technique, which can help in reducing the channel estimation overhead. There are two main types of switch diversity schemes, namely, switch and stay combining (SSC) and switch and examine combining (SEC). We consider a SISO wireless scenario in which a single transmitting antenna is sending its message to the receiving antenna with the aid of multiple IRS panels. This communication scenario will arise as a typical application of uplink scenario for future 6G wireless systems. The outage probability (OP) expressions for dual‐IRS‐panel‐aided SSC system and multiple‐IRS‐panel‐aided SEC system are analyzed, respectively, over Rician fading channels. We derive tight approximate OP expressions in closed form for a large number of IRS elements. Further, we derive a simple asymptotic OP for studying diversity order and coding gain. The OP performance with respect to each system parameter is thoroughly explored. Several numerical OP results are presented with corresponding simulated OP results to validate the accuracy of the presented analytical analysis. [ABSTRACT FROM AUTHOR]

In this work, we study the possibility of using a new non-homogeneous stochastic diffusion process based on the Rayleigh density function to model the evolution of the active cases of COVID-19 in Morocco. First, the main probabilistic characteristics and analytic expression of the proposed process are obtained. Next, the parameters of the model are estimated by the maximum likelihood methodology. This estimation and the subsequent statistical inference are based on the discrete observation of the variable x (t) "number of active cases of COVID-19 in Morocco" by using the data for the period of 28 January to 4 March 2022. Then, we analyze the mean functions by using simulated data for fit and forecast purposes. Finally, we explore the illustration of using this new process to fit and forecast the active cases of COVID-19 data. [ABSTRACT FROM AUTHOR]

A networked control system is an enhanced version of a control system that works in tandem with two independent technologies, viz. communication and control. One of the major concerns in using wireless channels for measurement and control data transfer is packet drops. These packet drops can be correlated in time when considering a more realistic channel condition such as fading. The goal of this study is to develop a state estimation algorithm and optimal control strategy for networked control systems in the presence of correlated packet drops, determine bounds on estimation error covariance and validate the results through simulations using a specific mobile robot model. [ABSTRACT FROM AUTHOR]

In this manuscript, the regulation of one degree-of-freedom Euler–Lagrange systems subject to input saturation is addressed. In particular, the design and analysis of a nonlinear static state feedback controller is presented. As a result, it is proven via Lyapunov's direct method that, in the presence of Rayleigh dissipation, the closed-loop equilibrium point is globally asymptotically stable with a strict Lyapunov function. Since saturation occurs in the system which contains the actuator model, the proposed control law is unconstrained and can be simplified to a proportional-derivative with desired gravity compensation algorithm. As a by-product global asymptotic stability is also proven for the case where Rayleigh dissipation is null. Numerical simulations on a crank-slider mechanism are presented. Moreover, experimental results on a DC-DC buck power converter are also shown and confirm the viability of our approach. [ABSTRACT FROM AUTHOR]

In cooperative spectrum sensing (CSS), in order to maximise the energy efficiency (EE) of cognitive radio (CR) users, users are divided into clusters. In this paper, the optimal inter-fusion rule threshold formula for different number of clusters and users is proposed for maximum EE in cluster-based CSS (CB-CSS). Different fusion rules are investigated for this purpose over Nakagami and Rician fading channel conditions. Simulations are conducted for different number of clusters and users using AND and OR intra-fusion rules and inter-fusion rule threshold is optimised in CB-CSS over the Nakagami-m fading channel and the Rician fading channel. The obtained mathematical expression for the inter-fusion rule threshold is verified by the results. It is investigated that when number of clusters are P = 4 and number of users in a cluster are K = 6 , OR-AND ( n = 1 , r = P) fusion rule achieves 2.46% more EE than AND-OR ( n = K , r = 1) fusion rule in case of Nakagami fading channel and 5.06% more EE than AND-OR fusion rule in case of Rician fading channel. Further, EE with respect to number of users is compared between additive white gaussian noise (AWGN) channel and Nakagami and Rician fading channels. [ABSTRACT FROM AUTHOR]

Electromagnetic nano communication (EMNC) is an evolving field of modern communication technology. Terahertz imaging, sensing, food safety and security, quality control and simultaneous localisation and mapping, which all together make it a suitable use case for 6 G, are the most lively applications of EMNC. This manuscript proposes unified expressions of error rate under different modulation schemes for EMNC. For this, mixture gamma (MG) fading distribution, including almost all the fading channels, under dual selection combining (SC) diversity is developed and employed. Also, generalised Gaussian distribution (GGD), which is appropriate for the EMNC system under an aqueous medium, is employed in the analysis. Specifically, analytical expressions for BER of BPSK, M-PAM and M-QAM schemes over MG fading under dual SC diversity are derived in the presence of GGD noise. Proposed analytical expressions are numerically compared with those available in the literature without SC diversity. Comparison shows that irrespective of the value of fading severity ' m ' and/or noise shaping parameter ' p ', dual SC offers a significant improvement in BER. It is most important to mention that proposed expressions are unified in nature because a variety of results can be reproduced for different values of ' N ' and ' p '. [ABSTRACT FROM AUTHOR]

User location is becoming an increasingly common and important feature for a wide range of services. Smartphone owners increasingly use location-based services, as service providers add context-enhanced functionality such as car-driving routes, COVID-19 tracking, crowdedness indicators, and suggestions for nearby points of interest. However, positioning a user indoors is still problematic due to the fading of the radio signal caused by multipath and shadowing, where both have complex dependencies on the indoor environment. Location fingerprinting is a common positioning method where Radio Signal Strength (RSS) measurements are compared to a reference database of previously stored RSS values. Due to the size of the reference databases, these are often stored in the cloud. However, server-side positioning computations make preserving the user's privacy problematic. Given the assumption that a user does not want to communicate his/her location, we pose the question of whether a passive system with client-side computations can substitute fingerprinting-based systems, which commonly use active communication with a server. We compared two passive indoor location systems based on multilateration and sensor fusion using an Unscented Kalman Filter (UKF) with fingerprinting and show how these may provide accurate indoor positioning without compromising the user's privacy in a busy office environment. [ABSTRACT FROM AUTHOR]

Internet of Things (IoT) systems cooperative with unmanned aerial vehicles (UAVs) have been put into use for more than ten years, from transportation to military surveillance, and they have been shown to be worthy of inclusion in the next wireless protocols. Therefore, this paper studies user clustering and the fixed power allocation approach by placing multi-antenna UAV-mounted relays for extended coverage areas and achieving improved performance for IoT devices. In particular, the system enables UAV-mounted relays with multiple antennas together with non-orthogonal multiple access (NOMA) to provide a potential way to enhance transmission reliability. We presented two cases of multi-antenna UAVs such as maximum ratio transmission and the best selection to highlight the benefits of the antenna-selections approach with low-cost design. In addition, the base station managed its IoT devices in practical scenarios with and without direct links. For two cases, we derive closed-form expressions of outage probability (OP) and closed-form approximation ergodic capacity (EC) generated for both devices in the main scenario. The outage and ergodic capacity performances in some scenarios are compared to confirm the benefits of the considered system. The number of antennas was found to have a crucial impact on the performances. The simulation results show that the OP for both users strongly decreases when the signal-to-noise ratio (SNR), number of antennas, and fading severity factor of Nakagami-m fading increase. The proposed scheme outperforms the orthogonal multiple access (OMA) scheme in outage performance for two users. The analytical results match Monte Carlo simulations to confirm the exactness of the derived expressions. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical framework using multiple reconfigurable intelligent surfaces (RISs) for enhancing the secrecy performance of wireless systems. In particular, multiple RISs are exploited to support transmitter-legitimate user communication under the existence of an eavesdropper. Two practical scenarios are investigated, i.e., there are only transmitter-eavesdropper links (case 1) and there are both transmitter-eavesdropper and transmitter-RIS-eavesdropper links (case 2). We mathematically obtain the closed-form expressions of the average secrecy capacity (ASC) of the considered system in these two investigated cases over Nakagami-m fading channels. The impacts of the system parameters, such as the locations of the RISs, the number of REs, and the Nakagami-m channels, are deeply evaluated. Computer simulations are used to validate our mathematical analysis. Numerical results clarify the benefits of using multiple RISs for improving the secrecy performance of wireless systems. Specifically, the ASCs in cases 1 and 2 are significantly higher than that in the case without RISs. Importantly, when the locations of the RISs are fixed, we can arrange the larger RSIs near either the transmitter or legitimate user to achieve higher ASCs. In addition, when the numbers of reflecting elements (REs) in the RISs increase, the ASCs in cases 1 and 2 are greatly enhanced. [ABSTRACT FROM AUTHOR]

Generalized frequency division multiplexing (GFDM) system with maximal ratio transmission (MRT) scheme is considered to analyse the symbol error rate (SER) performance over α - μ fading channel. In present days, low latency and low consumption of energy devices are used and these can be achieved using multicarrier techniques. The GFDM is one such multicarrier technique which has a capable to provide these requirements. Low out-of-band (OOB) radiation is one of the GFDM technique's main benefits. Initially, in this study, GFDM-MRT system is used to investigate the SER expression analysis in α - μ fading. Initially, we have addressed the closed form of novel mathematical analysis of SER expression under α - μ fading channel. The Rayleigh, Nakagami-m, and Nakagami-q fading channels are all special instances in the suggested derivation. Later, a Monte-Carlo simulation-based test-bed is developed in MATLAB software and simulations are evaluated for various values of fading parameters, different roll-off factors, and the number of transmitting antennas Nt. The GFDM-MRT technology provides lower SER values and it is more dependable for highspeed communications, it can be inferred. The main object of this paper is to compare the SER of GFDM-MRT system with GFDM system without using MRT technique in α - μ fading channel for different comparing parameters like at number of transmitting antennas Nt, different values of roll-off factors (β) and fading parameters α and μ. [ABSTRACT FROM AUTHOR]

Terahertz (THz) band offers a vast amount of bandwidth and is envisioned to become a key enabler for a number of next generation wireless applications. In this direction, appropriate channel models, encapsulating the large and small-scale fading phenomena, need to be developed for both indoor and outdoor communications environments. The THz large-scale fading characteristics have been extensively investigated for both indoor and outdoor scenarios. The study of indoor THz small-scale fading has recently gained the momentum, while the small-scale fading of outdoor THz wireless channels has not yet been investigated. Motivated by this, this contribution introduces Gaussian mixture (GM) distribution as a suitable small-scale fading model for outdoor THz wireless links. In more detail, multiple outdoor THz wireless measurements recorded at different transceiver separation distance are fed to an expectation-maximization fitting algorithm, which returns the parameters of the GM probability density function. The fitting accuracy of the analytical GMs is evaluated in terms of the Kolmogorov-Smirnov, Kullback-Leibler (KL) and root-mean-square-error (RMSE) tests. The results reveal that as the number of mixtures increases the resulting analytical GMs perform a better fit to the empirical distributions. In addition, the KL and RMSE metrics indicate that the increase of mixtures beyond a particular number result to no significant improvement of the fitting accuracy. Finally, following the same approach as in the case of GM, we examine the suitability of mixture Gamma to capture the small-scale fading characteristics of the outdoor THz channels. [ABSTRACT FROM AUTHOR]

Summary: To achieve high data rates expected from beyond 5G communications, higher‐order modulation techniques have been explored. The energy‐efficient modulation technique with a high data rate has encouraged researches towards an optimum two‐dimensional hexagonal‐shaped constellation, namely, hexagonal quadrature amplitude modulation (HQAM). Thus, in this work, we analyze the average symbol error rate (ASER) of HQAM schemes by considering a two‐user nonorthogonal multiple access (NOMA) pair. Closed‐form expressions for ASER of HQAM schemes for users are derived over generalized Nakagami‐ m fading channels. Further, for the HQAM constellation feasibility in two‐user downlink NOMA systems, the power allocation criterion for the users is presented. Furthermore, the impact of modulation order of the users over the systems ASER analysis is investigated and valuable insights are drawn. [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]

Power control in an RS-coded orthogonal frequency division multiplex (OFDM) system with error-and-erasure correction decoding in Rayleigh fading channels was investigated. The power of each symbol within a codeword was controlled to reduce the codeword error rate (WER). Several RS-coded OFDM systems with power control are proposed. The WERs of the proposed systems as a function of the signal-to-noise ratio per bit were derived. We found that channel inversion at the transmitter in combination with the erasure generation by ordering fading amplitudes at the receiver provided the lowest WER among the considered systems. Furthermore, the erasure generation by ordering fading amplitudes was found to be better than the erasure generation by comparing fading amplitudes with a threshold. [ABSTRACT FROM AUTHOR]

This paper improves energy efficiency and communications reliability for wireless transmission under κ - μ shadowed fading (i.e., integrating all channel impairments including path loss, shadowing, fading) and hardware impairment by employing a nonlinear energy harvester and multi-antenna power transmitter. To this end, this paper provides explicit formulas for outage probability. Numerous results corroborate these formulas and expose that energy-harvesting nonlinearity, hardware impairment, and channel conditions drastically deteriorate system performance. Notwithstanding, energy-harvesting nonlinearity influences system performance more severely than hardware impairment. In addition, desired system performance is accomplished flexibly and possibly by choosing a cluster of specifications. Remarkably, the proposed communications scheme obtains the optimal performance with the appropriate selection of the time-splitting factor. [ABSTRACT FROM AUTHOR]

This paper proposes a novel M -ary differential permutation index (DPI) differential chaos shift keying (DCSK) by using the Bahl–Cocke–Jeline–Raviv (BCJR) decoding (DPI-DCSK-BCJR) for chaos-based communications. By exploiting the characteristics of differential modulation and quasi-orthogonality of chaotic signals, the proposed DPI-DCSK-BCJR can provide two more calculated energies to decide the transmitted bits. Theoretical analysis of bit-error-rate (BER) is carried out over multipath Rayleigh fading channel and then validated via simulations. The proposed scheme is demonstrated to outperform the conventional DPI-DCSK by 2 dB for different M. This performance gain is especially increased over high-delay channels. Furthermore, the advantage of the proposed frequency-modulated DPI-DCSK-BCJR is verified over practical ultra-wideband (UWB) wireless channels. In addition, we investigate the proposed DPI-DCSK-BCJR for more generalized multiuser communications. The simulation result shows that DPI-DCSK-BCJR can achieve performance gains up to 5 dB as compared to the conventional PI-DCSK and DPI-DCSK for both two and three user systems. Consequently, the proposed DPI-DCSK-BCJR can be considered as a low-cost alternative for low-complexity and high-rate chaotic-based wireless communication. [ABSTRACT FROM AUTHOR]

Vehicular ad hoc networks (VANETs) have recently drawn a large amount of attention because of their enormous potential in road safety improvement and traffic management as well as infotainment service support. As the standard of medium access control (MAC) and physical (PHY) layers for VANETs, IEEE 802.11p has been proposed for more than a decade. Though performance analyses of IEEE 802.11p MAC have been performed, the existing analytical methods still need to be improved. In this paper, to assess the saturated throughput and the average packet delay of IEEE 802.11p MAC in VANETs, a two-dimensional (2-D) Markov model is introduced by considering the capture effect under Nakagami-m fading channel. Moreover, the closed-form expressions of successful transmission, collided transmission, saturated throughput, and average packet delay are carefully derived. Finally, the simulation results are demonstrated to verify the accuracy of the proposed analytical model, which also proves that this analytical model is more precise than the existing ones in terms of saturated throughput and average packet delay. [ABSTRACT FROM AUTHOR]

For a serial relaying underwater wireless optical communication (UWOC) system with ON‐OFF keying modulation, we theoretically evaluate the optimal power allocation techniques in order to minimise the end‐to‐end bit error rate (BER), subject to transmission power constraints. At first, we evaluate the end‐to‐end BER with respect to all degrading effects of the UWOC channel, namely scattering, absorption, and turbulence‐induced fading and then develop a closed‐form BER expression as a function of transceiver parameters and water type. The optimal power allocation methods are obtained using the perfect channel state information available at the receiver (CSIR) and transmitter (CSIT) for both detect‐and‐forward (DF) and amplify‐and‐forward (AF) serial relaying systems. For each relaying method, we consider a dual‐hop UWOC system and determine optimal power allocation to minimise the BER. Afterwards, the optimal power allocation in a multi‐hop system is obtained to minimise the end‐to‐end BER. Compared to the equal power allocation, our results illustrate that UWOC relaying systems with optimal power allocation can significantly improve the end‐to‐end BER and expand the communication link. For instance, the proposed power allocation method for the DF and AF relay node in a 60 m single relay system improves the system performance at the BER of 10−5 by 2.5 and 1.8 dB compared to the equal power allocation, respectively. [ABSTRACT FROM AUTHOR]

This paper studies the problem of membership-function-dependent memory output feedback (MOF) controller design for interval type-2 (IT2) fuzzy systems under fading channels. A time-varying stochastic process is introduced to model the unpredictable channel fading phenomenon. Taking the impact of channel fading into consideration, a non-parallel distribution compensation (non-PDC) strategy is employed to construct a class of memory output feedback fuzzy controllers. By fully exploiting the membership functions, the membership-function-dependent performance analysis and controller synthesis results have been obtained, such that the closed-loop system can be guaranteed with mean-square exponential stability and H ∞ performance γ. Finally, simulation studies have been presented to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]