In this paper, we investigate the performance of wireless-powered communication (WPC) systems operating under the harvest-then-transmit protocol with a three-piecewise nonlinear energy harvesting (EH) model, which explicitly captures the sensitivity and saturation behavior of practical EH circuits. In parallel, we adopt a versatile fading characterization by assuming Nakagami-mchannels in the EH phase and generalized Gamma channels in the information transfer phase, the latter being of practical interest as it unifies several standard fading distributions and accurately approximates fading environments in next-generation networks. Based on this setting, we develop a novel analytical framework that yields, for the first time, exact analytical expressions for the average throughput in the delay-limited, delay-tolerant, and Quality of Service (QoS) delay-constrained transmission modes. We then apply the developed framework to study the throughput of WPC-enabled reconfigurable intelligent surface-assisted systems as a direct application example. We conduct extensive Monte-Carlo simulations under various system configurations to confirm the accuracy of the analytical results. Our results show that nonlinear EH effects yield a more realistic benchmark for the average throughput compared to the conventional linear EH model, particularly under stringent sensitivity and saturation constraints.

Thermal noise modulation (TNM) encodes information in thevarianceof Johnson noise, enabling ultra-low/zeropower operation with intrinsic physical-layer security. While recent demonstrations have focused on binary TNM, its twolevel alphabet fundamentally limits spectral efficiency. This paper develops anM-ary TNM (M-TNM) framework that maps symbols to multiple variance levels, thereby conveying (log2M) bits per channel use. We first establish a structural property of the optimal detector: for zero-mean Gaussian classes with ordered variances, the maximum-likelihood (ML) decision regions are contiguous in the energy statistic and each symbol’s boundaries depend only on its two adjacent variance levels. Leveraging this result, we derive closed-form expressions for theoptimalML detection thresholds and the associatedexactaverage symbol error rate (SER) forM-TNM. We then formulatevariance-constellation optimization—the selection and spacing of symbol variances—as a SER-minimization problem under practical constraints. Analytical results are validated via extensive Monte Carlo simulations, which show near-perfect agreement with theory and demonstrate substantial BES reductions for optimized constellations compared with naïve (e.g., uniformly spaced) variance levels. The proposedM-TNM framework thus improves spectral efficiency while preserving TNM’s energy and security promise, positioning variance-domain modulation as a viable physical-layer technique for bandwidth-limited, large-scale Internet of Things (IoT) deployments.

This work investigates the bit error probability (BEP) of thermal noise modulation (TNM) in Rayleigh fading channels. TNM has emerged as a promising ultra-low-power modulation scheme, where information is conveyed through variations in thermal noise variance. Existing studies provide only approximate BEP expressions and assume perfect channel state information (CSI) at the receiver. Furthermore, current detection strategies require per-symbol threshold adjustments, which, along with CSI estimation, introduce significant computational overhead for power-constrained devices. To address these limitations, we propose a fixed-threshold detection strategy that eliminates the need for channel estimation and threshold adaptation. Additionally, we derive an exact closed-form BEP expression for TNM under Rayleigh fading and formulate the problem of optimal threshold selection as an optimization task, solvable using efficient line-search techniques such as gradient descent. The accuracy of our analytical results is validated through Monte Carlo simulations, demonstrating strong agreement with theoretical predictions. These contributions provide a more precise characterization of TNM performance in fading environments, paving the way for its practical implementation in energy-efficient wireless systems.

The objective of this paper is to address the following question: Are shadowing, multi-path, and line-of-sight (LoS) effects friends or foes? To this end, we examine shadowed k-μ fading channels as they characterize shadowing, multi-path and LoS components. Furthermore, we explore the impact of various types of shadowing. To answer the main question of this paper, we consider different wireless communication systems, including selection combining, maximal-ratio combining, equal-gain combining, and space-shift keying multiple-input multiple-output modulation. Extensive Monte-Carlo simulation results reveal that there is no single definitive answer. In other words, the aforementioned phenomena can either be advantageous or disad-vantageous depending on the type of the wireless communication system. However, it is important to note that these insights apply to both perfect channel state information (CSI) and imperfect CSI.

This paper studies an Internet-of-Things (IoT) network employing a reconfigurable intelligent surface (RIS) over generalized fading channels. Inspired by the promising potential of RIS-based transmission, we investigate a RIS-enabled IoT network with the source node employing a RIS-based access point. The system is modelled with reference to a receiver-transmitter pair and the Fisher-Snedecor F model is adopted to analyse the composite fading and shadowing channel. Closed-form expressions are derived for the system with regards to the average capacity, average bit error rate (BER) and outage probability. Monte-Carlo simulations are provided throughout to validate the results. The results investigated and reported in this study extend early results reported in the emerging literature on RIS-enabled technologies and provides a framework for the evaluation of a basic RIS-enabled IoT network over the most common multipath fading channels. The results indicate the clear benefit of employing a RIS-enabled access point, as well as the versatility of the derived expressions in analysing the effects of fading and shadowing on the network. The results further demonstrate that for a RIS-enabled IoT network, there is the need to balance between the cost and benefit of increasing the RIS cells against other parameters such as increasing transmit power, especially at low SNR and/or high to moderate fading/shadowing severity.

In this paper, the performance of a mobile receiver in an Internet-of-Things (IoT) network is analyzed. In particular, a multi-antenna base-station sends information signals to a mobile receiver. The receiver employs the maximal-ratio transmission technique to improve the quality of the received signal. The mobility of the receiver is characterized by the well-known random waypoint mobility model. The wireless fading channels between the base-station and the receiver is described by the composite F fading model. Closed-form analytical expressions for several important metrics such as outage probability, average bit error rate, and average channel capacity are derived. The analytical expressions are validate by numerical and Monte-Carlo simulations.

In this paper, we consider a wireless-powered communication network with transmit antenna selection (TAS), where an energy-limited multi-antenna information source, powered by a dedicated power beacon, communicates with a mobile user (MU). The MU is equipped with a single-antenna and its mobility is characterized by the well-known random waypoint mobility model. Differently from previous works which considered only static scenarios, this paper aims to investigate wireless power and information transfer in the scenario with a random mobile user under Nakagami-m fading. To this end, exact analytical expressions for the outage probability, average delay-limited throughput, ergodic capacity, and average delay-tolerant throughput are derived. The analytical results are compared with Monte-Carlo simulations in order to validate the analysis and provide useful insights on the impact of different parameters on the system performance.

In this paper, we investigate the performance of energy detection-based spectrum sensing over F composite fading channels. To this end, an analytical expression for the average detection probability is first derived. This expression is then extended to account for collaborative spectrum sensing, square-law selection diversity reception, and noise power uncertainty. The corresponding receiver operating characteristics (ROC) are analyzed for different conditions of the average signal-to-noise ratio (SNR), noise power uncertainty, time-bandwidth product, multipath fading, shadowing, number of diversity branches, and number of collaborating users. It is shown that the energy detection performance is sensitive to the severity of the multipath fading and the amount of shadowing, whereby even small variations in either of these physical phenomena can significantly impact the detection probability. As a figure of merit to evaluate the detection performance, the area under the ROC curve (AUC) is derived and evaluated for different multipath fading and shadowing conditions. Closed-form expressions for the differential entropy and cross entropy are also formulated and assessed for different average SNR, multipath fading, and shadowing conditions. Then, the relationship between the differential entropy of F composite fading channels and the corresponding ROC/AUC is examined where it is shown that the average number of bits required for encoding a signal becomes small (i.e., low differential entropy) when the detection probability is high or when the AUC is large. The difference between composite fading and traditional small-scale fading is emphasized by comparing the cross entropy for Rayleigh and Nakagami-m fading. A validation of the analytical results is provided through a careful comparison with the results of some simulations.

This paper investigates the performance of energy detection-based spectrum sensing over Fisher-Snedecor F fading channels. To this end, an analytical expression for the corre- sponding average detection probability is firstly derived and then this is extended to account for collaborative spectrum sensing. The complementary receiver operating characteristics (ROC) are analyzed for different conditions of the average signal-to- noise ratio (SNR), time-bandwidth product, multipath fading, shadowing and number of collaborating users. It is shown that the energy detection performance is strongly linked to the severity of the multipath fading and amount of shadowing, whereby even small variations in either of these physical phenomena significantly impact the detection probability. Also, the versatile modeling capability of the Fisher-Snedecor F distribution is verified in the context of energy detection based spectrum sensing as it provides considerably more accurate characterization than the conventional Rayleigh fading model. To confirm the validity of the analytical results presented in this paper, we compare them with the results of some simulations.

The Fisher-SnedecorFdistribution was recently proposed as an accurate and tractable composite fading model in the context of device-to-device communications. The present work derives the product of the Fisher-SnedecorFcomposite fading model, which is useful in characterizing fading effects in numerous realistic communication scenarios. To this end, novel analytic expressions are first derived for the probability density function, the cumulative distribution function and the moment of the product ofNstatistically independent, but not necessarily identically distributed, Fisher-SnedecorFrandom variables. Capitalizing on these expressions, we derive tractable closed-form expressions for channel quality estimation of the proposed model as well as the corresponding outage probability and average bit error probability for binary modulations. The offered results are corroborated by extensive Monte-Carlo simulation results, which verify the validity of the derived expressions. It is shown that the number of cascaded channels affects considerably the corresponding performance, as a variation of over an order of magnitude is observed across all signal-to-noise ratio regimes.

The performance of physical-layer security of the classic Wyner's wiretap model over Fisher-Snedecor F composite fading channels is considered in this work. Specifically, the main channel (i.e., between the source and the legitimate destination) and the eavesdropper's channel (i.e., between the source and the illegitimate destination) are assumed to experience independent quasi-static Fisher-Snedecor F fading conditions, which have been shown to be encountered in realistic wireless transmission scenarios in conventional and emerging communication systems. In this context, exact closed-form expressions for the average secrecy capacity (ASC) and the probability of non-zero secrecy capacity (PNSC) are derived. Additionally, an asymptotic analytical expression for the ASC is presented. The impact of shadowing and multipath fading on the secrecy performance is investigated. Our results show that increasing the fading parameter of the main channel and/or the shadowing parameter of the eavesdropper's channel improves the secrecy performance. The analytical results are compared with Monte-Carlo simulations to validate the analysis.

In this work, the authors study the performance of decode‐and‐forward cognitive multi‐hop networks in an underlay spectrum sharing strategy for Nakagami‐ m fading channels with additive white generalised Gaussian noise. To this end, new exact analytical expressions for the average bit error rate of M ‐ary quadrature amplitude modulation ( M ‐QAM) and M ‐ary phase shift keying are derived and evaluated. In addition, an exact expression for the average symbol error rate of M ‐QAM is provided. Moreover, lower‐ and upper‐bound expressions for the ergodic capacity are obtained. Different scenarios are presented to study the influence of various key system parameters, such as fading severity, noise shaping parameter, and interference temperature, on the system performance. The obtained analytical results are supported with Monte Carlo simulations to confirm the accuracy of the analytical derivations.

In this paper, we analyze the performance of decode-and-forward (DF) dual-hop relaying networks with wireless energy harvesting at the relay node over the generalized η-μ and κ-μ fading channels. In the analysis, the source and destination nodes are equipped with multiple antennas, whereas the relay node is equipped with a single antenna. Exact analytical expression for the system outage probability (OP) is derived and evaluated. The derived OP expression considers two practical energy harvesting techniques, namely, time switching-based relaying (TSR) and power splitting-based relaying (PSR). Some numerical examples are provided to study the overall system performance under different system parameters, such as fading parameters, energy harvesting time, power splitting factor, and signal-to-noise ratio (SNR). Our numerical results are supported with Monte-Carlo simulations to validate the accuracy of our analysis.

In this study, the authors consider the α − η − μ fading channels and derive a new form for the cumulative distribution function of the signal‐to‐noise ratio (SNR) in terms of the bivariate Fox H‐function. They also derive closed‐form expressions for the moments and the amount of fading of the SNR. The capacity of α − η − μ fading channels is analysed assuming different adaptive transmission protocols. To this end, they provide analytical closed‐form expressions for the average channel capacity with optimal rate adaptation ( C ORA ), optimal power and rate adaptation ( C OPRA ), channel inversion with fixed rate (CIFR) ( C CIFR ), and truncated CIFR ( C TIFR ). The derived expressions are valid for arbitrary values of the α , η , and μ fading parameters. The derived expressions can also be reduced to study the capacity of other fading distributions such as η − μ, α − μ , Weibull, and Nakagami. Numerical results are provided and compared with simulations to validate of the derived expressions.

In this paper, we analyze multiple-input multiple-output quadrature spatial modulation (QSM-MIMO) systems that operate under imperfect channel information over correlated α-μ fading channels. A simple and closed-form expression for the pairwise error probability (PEP) is provided. Based on the obtained PEP, a closed-form upper bound expression for the average bit error probability (BEP) is obtained. The obtained results clearly show the effect of the fading parameters on the average BEP. In case of the α-μ fading channels, increasing a has larger negative impact on the average BEP compared to increasing μ. In addition, the results demonstrate that the correlation coefficient of the transmit-antennas significantly deteriorates the average BEP when compared to the correlation coefficient of the receive-antennas.

In this study, the authors analyse the performance of maximal‐ratio combining in η − μ fading channels under imperfect channel estimation. More specifically, unified and novel analytical expressions for the average symbol error probability (SEP) and average channel capacity are obtained. The average SEP expression is valid for a wide range of coherent and non‐coherent modulation schemes. The system performance is analysed and discussed through some representative numerical examples. Furthermore, to validate the correctness of the authors’ derivations, the numerical results are compared with Monte‐Carlo simulation results. Both results are in excellent agreement over a wide range of average signal‐to‐noise ratio and different values of the fading parameters.

In this paper, we present a comprehensive framework for quadrature spatial modulation (QSM) in generalized fading channels. In particular, the performance analysis of QSM systems in the presence of imperfect channel knowledge and under correlated fading channels is presented. A simple and closed-form expression for the pairwise error probability (PEP) is provided. Based on the obtained PEP, a closed-form upper bound expression for the average bit error probability (BEP) is obtained. The analysis is unified in the sense that it is applicable for any fading channel once its envelope and phase distributions are available. As such, different generalized fading distribution models, namely, η-μ, κ-μ, and α-μ distributions, are considered. The obtained results clearly show the influence of the fading parameters on the average BEP. In the case of the α-μ fading channels, increasing α has larger negative impact on the average BEP compared with increasing μ. For the κ-μ channels, increasing μ results in increasing the average BEP dramatically when compared with increasing κ. In the same context, in η-μ fading channels, as μ increases the average BEP degrades whereas increasing η slightly improves the average BEP. In addition, it is demonstrated that transmit-antenna correlation significantly deteriorate the average BEP when compared with receive-antenna correlation.

Space modulation techniques, such as spatial modulation (SM) and space shift keying (SSK), are spatial multiplexing MIMO techniques that use multiple transmit- and receive-antenna in a new and resourceful fashion to enhance the overall spectral efficiency of wireless communication systems. In this paper, the performance of space modulations over the generalized κ-μ fading channels under imperfect channel state information (CSI) is analyzed. In particular, a generalized, simple and exact closed-form expression for the pairwise error probability (PEP) of SM- and SSK-MIMO systems that operate over the generalized κ - μ fading channels is derived and evaluated. The PEP expression jointly considers the envelope-phase distribution of the fading channel. Based on the derived PEP and the union bound technique, a closed-form expression for the average bit error rate (BER) is obtained. The system performance is analyzed and discussed through representative numerical examples over a wide range of the fading parameters (κ and μ) and under the channel estimation error. The numerical results are corroborated with Monte-Carlo simulations to validate our analytical results.

This paper analyzes the performance of space modulation techniques over generalized fading channels with imperfect channel estimation. In particular, a unified approach for calculating the pairwise error probability (PEP) of spatial modulation (SM) and space shift keying (SSK) modulation techniques for multiple-input multiple-output (MIMO) wireless communication systems is presented. A new, simple, and exact closed-form expression for the PEP over generalized α-μ fading channels under imperfect channel state information (CSI) is derived. The PEP expression considers the joint distributions of the envelope and the phase of the fading channel. Furthermore, the derived PEP and the union bound technique are used to obtain a closed-form expression for the average bit error rate (BER). The influence of the fading parameters α and μ and the channel estimation error on the system performance is analyzed and discussed through representative numerical examples. The correctness of our derivations is validated by means of MonteCarlo simulations.

The end-to-end performance of dual-hop relaying networks with beamforming over generalized η-μ fading channels is investigated. In our analysis, we assume fixed-gain relays with single antennas, whereas the source and destination terminals are equipped with multiple antennas. Novel expressions for the generalized moments of the end-to-end signal-to-noise ratio (SNR), the cumulative density function (CDF), probability density function (PDF), and moment generating function (MGF) are derived. These analytical expressions are then used to derive new expressions for Rayleigh fading channels as a special case. The new derived expressions, for Rayleigh fading channels, for the PDF and MGF of the end-to-end SNR are simpler and more tractable than those reported in the literature. Simulation results show the tightness and accuracy of the newly derived expressions.

In this work we investigate the problem of video streaming in cognitive radio networks from a cognitive radio video source to a set of cognitive radio destinations using multicasting. Our objective is to improve the overall quality of the received video by all destinations. To achieve this, we propose a cross layer approach to multicast the video packets. The video source implements the proposed approach to multicast a video packet to all destinations at the same time by selecting the best unified channel of all available channels for all destinations to send the video packet on. To select the best unified channel, the source jointly considers the required transmission time of the packet and the average spectrum availability time of the available channels. Moreover, by using the proposed approach, the video source guarantees that the required transmission time of the packet over the selected channel is less than its average spectrum availability time. We conduct simulation experiments to evaluate the performance of our proposed protocol under various network parameters. We compare our protocol with three multicast protocols. The first one selects the unified channel based on the minimum transmission time. The second one selects the unified channel based on the average spectrum availability time. The last one selects the unified channel randomly. We use packet delay, the ratio of bad frames, and control overhead as performance metrics. Simulation results demonstrate that the proposed multicasting routing protocol achieves significantly better performance compared to the other studied routing protocols in terms of all studied performance metrics. Specifically, it reduces the packet delay by at least 25%, the control overhead by at least 5%, and the ratio of bad frames 44%.

In this paper, we analyze and evaluate the performance of spatial modulation (SM) systems that operate over independent and identically distributed (i.i.d) η - μ fading channels. More specifically, a closed-form expression in terms of Appell's hypergeometric function for the pairwise error probability (PEP) is derived. Furthermore, simplifications for some special fading distributions such as Nakagami-m, Rayleigh, and Nakagami-q (Hoyt) are then presented. The derived expressions are valid for integer, as well as for non-integer values of μ. Simulation results demonstrate that the average bit error rate (BER) improves when η and μ increase, whilst the effect of μ is more pronounced than that of η.

The performance of dual-hop wireless communication systems with semi-blind amplify-and-forward (AF) relays over independent, but not necessarily identically distributed, η-μ fading channels is investigated. This performance is studied based on the evaluation of the outage probability, average bit-error probability (ABEP), and average end-to-end received signal-to-noise ratio (SNR). To this end, novel expressions for the outage probability and average end-to-end received SNR are derived. Moreover, an expression for end-to-end SNR of the probability density function (PDF) is derived. Based on the derived PDF, we then obtain a novel expression for the generalized moments of the received SNR. We conduct extensive simulation in order to study the effect of the fading parameters (i.e., η and μ) on the system performance. Our findings show that, in contrast to the fading parameter η, μ has a significant impact on the system performance. In addition, simulation results demonstrate that, the derived expressions match very well with the numerical simulations.

In this paper, we propose a novel CRN MAC, called MAX-PS-MAC. MAX-PS-MAC uses a probabilistic channel assignment mechanism that attempts at maximizing the packet success probability of each transmission by exploiting statistical information regarding availability durations and link quality conditions of idle channels. While most of previously proposed CRN MAC protocols account for PR channel dynamics by requiring communicating CR users to consistently perform dynamic channel switching according to PR activities, MAX-PS-MAC avoids the significant overhead and delay of channel switching by providing communicating CR users with the idle channel that provides the highest probability of success. Simulation results indicate that compared to typical CRN MAC protocols, MAX-PS-MAC significantly reduces the forced-termination rate of CR transmissions, which consequently improves network throughput by up to 110%.

Designing an appropriate routing metric in cognitive radio networks (CRNs) is a challenging problem. In a multi-hop CRN, both spectrum handoff (quantified by channel availability time) and required transmission time can significantly impact network connectivity and routing. Specifically, spectrum handoff can cause a significant degradation in CRN performance when the availability time of an assigned channel is smaller than the required transmission time over that channel. In this case, the percentage of CR transmissions that will be terminated due to primary user (PU) activities, can significantly increase, leading to a reduction in network throughput. To reduce the percentage of terminated CR transmissions, we introduce a novel routing metric that jointly considers spectrum availability time and required CR transmission time. Based on this metric, we propose a probabilistic routing algorithm for multi-hop CRNs that attempts at computing the path with the maximum probability of success from a given source to its destination (including the channel assignment along that path). Simulation results show that our proposed algorithm leads to a significant performance improvement over two reference algorithms presented in this paper.

This paper addresses the problem of video multicast for heterogeneous destinations in mobile ad hoc networks. Multiple Description Coding (MDC) is used for video coding. MDC generates multiple independent bit-streams, where the multiple bit-streams are referred to as multiple descriptions (MD). Furthermore, MDC enables a useful reproduction of the video when any description is correctly received. Specifically, we propose Sequential MDMTR (Multiple Disjoint Multicast Trees Routing) protocol for video multicast. It builds multiple disjoint multicast trees and assigns MD video in a centralized fashion. Sequential MDMTR protocol aims at increasing the number of assigned MD video to each destination. We extensively evaluate our proposed protocol by simulations and show that it outperforms the existing work.

In this paper, we investigate how Multiple Description Coding (MDC) can improve the user's satisfaction for a group of heterogeneous destinations for video multicast over wireless ad hoc networks. Specifically, we explore the independent-description property of MDC with multiple paths to improve the user's satisfaction. In our approach, the assignment of multiple description (MD) video is randomly done by a multicast source node. Based on the assignment of MD video, the multicast source constructs multiple multicast trees accordingly. Simulation results demonstrate that our approach can achieve higher user's satisfaction regardless of the multicast group size.

In this paper, we address the issue of video multicast for heterogeneous destinations in mobile ad hoc networks (MANETs). By exploiting multiple node-disjoint trees and multiple description coding (MDC), we propose an efficient video multicast routing protocol for heterogeneous destinations (EVMR-HD). EVMR-HD deploys, for the first time, the independent-description property of MDC to increase number of video descriptions requested by each destination and therefore improve the quality of the received video. Our results show that EVMR-HD outperforms Serial MDTMR in terms of several metrics.

This paper presents a novel approach for the construction of Multiple Shortest Path Trees (MSPT) using multiple description (MD) video coding to satisfy the destination requirements (i.e., each destination has a preference number, which depends on its capacity, of video layers). Specifically, the independent-descriptions property of multiple description (MD) video coding along with multiple trees are exploited to increase user satisfaction. This approach is suitable for heterogeneous wireless ad hoc networks. Simulation results demonstrate that our proposed scheme (MSPT-MDC) outperforms MSPT-LC (multiple trees with layered coding) in terms of user satisfaction. In addition, simulation results show that user satisfaction, of the proposed scheme, is insensitive to the change of the number of destinations.

In this paper, we address the issue of multilayered multicast routing in wireless ad hoc networks (WAHNs). Existing multilayered multicast protocols assume homogeneous ad hoc wireless networks; in which all nodes are of the same type (they have the same processing, data rate and communication capabilities and characteristics). A more realistic assumption is a heterogeneous network; in which nodes have different processing, communication capabilities and other characteristics. In this paper, we assume heterogeneous network; in which nodes have different capabilities. Two multilayered multicast routing algorithms are proposed, namely, multiple trees based on shortest path tree (MSPT) and multiple trees based on Steiner minimum tree (MSMT). We assume that each destination has a preference number of video layers; which is equal to its capacity. Moreover, we do not consider only the capacities of nodes in the network but also the bandwidth of each link. Simulations show that the proposed schemes greatly improve the QoS requirements (improve user satisfaction ratio (USR)) for a set of destinations. In addition, simulations show that multiple trees schemes achieve substantially higher satisfaction ratio than the single tree scheme.