Probability Of Non-zero Secrecy Capacity Research Articles

On the secrecy performance of RIS-enabled wireless communications over Nakagami-m fading channels

This paper examines the secrecy performance of reconfigurable intelligent surface aided wireless communication systems. Specifically, we derive the secrecy outage probability (SOP), intercept probability, probability of non-zero secrecy capacity, and ergodic secrecy capacity (ESC) expressions over Nakagami- m fading channels. We further evaluate the asymptotic SOP expressions to get some insights into the secrecy diversity order under two scenarios of interest; (1) when the signal-to-noise ratio approaches infinity, and (2) when the main-to-eavesdropper ratio tends to infinity. Also, we analytically show the effect of reflecting element density on the ESC performance. The numerical and simulation studies verify our analytical findings.

The Generalized-Fisher composite fading model for the next generation of mobile communication systems

The new generation of communication systems is moving towards using a millimeter-wave spectrum. Since the shadowing effects are undeniable in this type of propagation, the proposed Generalized Fisher (GF) distribution can be useful in modeling shadowed fading channels, considering the non-linearity and the multi-cluster nature of the diffusion medium. After introducing the model, its main statistics, including Probability Density Function (PDF), Cumulative Distribution Function (CDF), Moment Generating Function (MGF), and the distribution of the sum of an arbitrary number of independent and non-identically distributed (i.n.i.d.) random variables with GF distribution are calculated. Subsequently, some wireless communication application criteria such as ergodic and outage capacities, are computed. Finally, considering the classic Wyner's wiretap model and passive eavesdropping scenario, specific security criteria, such as the probability of non-zero secrecy capacity and secrecy outage probability, are also determined. These expressions are measured in terms of either univariate or multivariate Fox's H-function.

Physical-Layer Security for UAV-Assisted Air-to-Underwater Communication Systems with Fixed-Gain Amplify-and-Forward Relaying

We analyze a secure unmanned aerial vehicle-assisted two-hop mixed radio frequency (RF) and underwater wireless optical communication (UWOC) system using a fixed-gain amplify-and-forward (AF) relay. The UWOC channel was modeled using a mixture exponential-generalized Gamma distribution to consider the combined effects of air bubbles and temperature gradients on transmission characteristics. Both legitimate and eavesdropping RF channels were modeled using flexible α-μ distributions. Specifically, we first derived both the probability density function (PDF) and cumulative distribution function (CDF) of the received signal-to-noise ratio of the system. Based on the PDF and CDF expressions, we derived the closed-form expressions for the tight lower bound of the secrecy outage probability (SOP) and the probability of non-zero secrecy capacity (PNZ), which are both expressed in terms bivariate Fox’s H-function. To utilize these analytical expressions, we derived asymptotic expressions of SOP and PNZ using only well-known functions. We also used asymptotic expressions to determine the suboptimal transmitting power to maximize energy efficiency. Furthermore, we investigated the effect of levels of air bubbles and temperature gradients in the UWOC channel, and studied the nonlinear characteristics of the transmission medium and the number of multipath clusters of the RF channel on the secrecy performance. Finally, all analyses were validated using a simulation.

Mobile Collaborative Secrecy Performance Prediction for Artificial IoT Networks

The integration of artificial intelligence and Internet of Things (IoT) has promoted the rapid development of artificial IoT (AIoT) networks. A wide range of AIoT applications have generated a great deal of data. The fifth-generation (5G) mobile communication has powerful data processing capabilities, and it is a key technology to enable AIoT big data processing. The explosive growth of the 5G users has made information security in AIoT networks a significant issue. Real-time security evaluation in AIoT networks is difficult due to user mobility and dynamic wireless environments. Thus, the evaluation and prediction of secrecy performance is a very critical research. In this article, new expressions for the nonzero secrecy capacity probability (NSCP) are derived to evaluate the mobile collaborative secrecy performance. An improved convolutional neural network (CNN) model, named as SI-CNN in this article, is proposed to predict the NSCP performance. The SI-CNN model combines the SqueezeNet and InceptionNet, and it has four convolution layers, which all adopt the same convolution model. For the first two layers, they employ a 2 × 1 convolution and a three-branch convolution, which not only increase the number of channels but also extract more features. For the last two layers, they employ the same structure, but different convolution kernels. The proposed SI-CNN prediction algorithm is shown to provide better NSCP performance prediction than other state-of-the-art methods. In particular, compared with wavelet neural network, the prediction precision of SI-CNN is improved by 26.8%.

Secrecy performance analysis of amplify-and-forward relay cooperative networks with simultaneous wireless information and power transfer

Simultaneous wireless information and power transfer (SWIPT) is a promising technology to enhance the power constraint issue in the wireless networks. In this paper, we investigate the secrecy performance of a selective cooperative relaying network with an energy harvesting (EH) technique, in which a source terminal communicates with a legitimate user at the destination terminal through N amplify-and-forward (AF) relays in the presence of multiple eavesdroppers. The relays deploy SWIPT with power splitting-based relaying (PSR) and time switching-based relaying (TSR) protocols to harvest energy. We present closed-form expressions for the secrecy performance metrics, consisting of the probability of non-zero secrecy capacity, the secrecy outage probability, and the average secrecy capacity to evaluate the physical layer security (PLS) of the system. Using the mathematical expressions, we obtain numerical results under the parameters of the system. These results demonstrate that using relay selection can significantly improve the secrecy performance of the system. Moreover, we compare the cooperative relay system without SWIPT and the system with SWIPT. It is observed that depending on the distance of eavesdroppers from the relays and the destination, the system based on SWIPT may achieve a better PLS than the system without SWIPT. Finally, we provide Monte-Carlo simulation results to confirm the validity of our analysis.

On Securing Cognitive Radio Networks-Enabled SWIPT Over Cascaded $\kappa$-$\mu$ Fading Channels With Multiple Eavesdroppers

In this paper, the physical-layer security (PLS) for an underlay cognitive radio network (CRN) with multiple non-colluding eavesdroppers is studied. We assume that a secondary user (SU) transmitter communicates with an SU receiver over a cascaded <inline-formula><tex-math notation="LaTeX">$\kappa$</tex-math></inline-formula>-<inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> fading channel and under the threat of eavesdropping. A cooperative jammer exists to improve the SUs&#x2019; security by harvesting energy from the SU transmitter using power splitting technique. This harvested energy is utilized to generate jamming signals to deteriorate the eavesdroppers&#x2019; reception quality. Moreover, the eavesdroppers are assumed to be randomly distributed according to a homogeneous Poisson point process (HPPP), in which the <inline-formula><tex-math notation="LaTeX">$k^{th}$</tex-math></inline-formula> closest eavesdropper to the SU transmitter will be selected in our analysis. Additionally, the legitimate receiver is assumed to harvest energy from the SU transmitter using the power splitting technique. In this context, we propose an optimum power splitting factor at the legitimate receiver that achieves the best privacy while constraining the amount of the harvested energy. Furthermore, on enhancing system security, we investigate the effectiveness of the jamming technique. The impact of distances over security is also examined. The results reveal an improvement in privacy as the legitimate receiver utilizes the adaptable power splitting factor. PLS is evaluated in terms of the probability of non-zero secrecy capacity and the intercept probability.

Cascaded κ-μ Fading Channels with Colluding and Non-Colluding Eavesdroppers: Physical-Layer Security Analysis

In this paper, the physical-layer security for a three-node wiretap system model is studied. Under the threat of multiple eavesdroppers, it is presumed that a transmitter is communicating with a legitimate receiver. The channels are assumed to be following cascaded κ-μ fading distributions. In addition, two scenarios for eavesdroppers’ interception and information-processing capabilities are investigated: colluding and non-colluding eavesdroppers. The positions of these eavesdroppers are assumed to be random in the non-colluding eavesdropping scenario, based on a homogeneous Poisson point process (HPPP). The security is examined in terms of the secrecy outage probability, the probability of non-zero secrecy capacity, and the intercept probability. The exact and asymptotic expressions for the secrecy outage probability and the probability of non-zero secrecy capacity are derived. The results demonstrate the effect of the cascade level on security. Additionally, the results indicate that as the number of eavesdroppers rises, the privacy of signals exchanged between legitimate ends deteriorates. Furthermore, in this paper, regarding the capabilities of tapping and processing the information, we provide a comparison between colluding and non-colluding eavesdropping.

Physical layer secrecy performance analysis of relay selection in a cooperative wireless network

This paper investigates the performance of physical (PHY) layer secrecy in a cooperative relaying with opportunistic relay selection, where an eavesdropper intercepts the transmit signals between the authorized users. At first, theoretical expressions are derived for three performance criteria for evaluating the PHY security, namely: the secrecy outage probability, the average of secrecy capacity, and the probability of non-zero secrecy capacity. Then the secrecy performance in information transmissions is investigated. Moreover, using the computer simulations, the validity of the derived expressions and the carried out analyses are examined and verified. To show the enhancement on the secrecy performance in the presented system that employs opportunistic relay selection, the secrecy outage probabilities of the opportunistic relay selection system, one relay cooperation system, and direct transmission system are also compared.

Reconfigurable Intelligent Surfaces-Aided Physical Layer Security Enhancement in D2D Underlay Communications

This letter investigates a reconfigurable intelligent surfaces (RIS)-aided wireless communication system in an inband underlay Device-to-Device (D2D) communication, where the direct link between D2D users is unavailable. An RIS is used to adjust its reflecting elements to enhance the D2D communication data transmission while improving the cellular network's secrecy performance concurrently. Specifically, analytical results for the secrecy outage probability and the probability of non-zero secrecy capacity are derived for the cellular network. Moreover, the D2D outage probability is also provided. Simulation and analytical results are presented to verify the derived expressions' correctness and the effectiveness of the proposed scenario. Moreover, the asymptotic results are presented.

On the Performance of Secure Underlay Cognitive Radio Networks With Energy Harvesting and Dual-Antenna Selection

In this letter, we consider a secure underlay cognitive radio network consisting of a secondary source-destination pair and a primary transmitter-receiver pair in the presence of a primary passive eavesdropper. Herein, a secondary multi-antenna full-duplex destination node acts as a jammer to the primary eavesdropper in an effort to improve the physical layer security of the primary network. In return for this favor, the energy constrained secondary source gets access to the primary network to transmit its own information so long as the interference to the latter is below a certain level. In light of the aforementioned, we evaluate the system performance in terms of the outage probability for the secondary network, the secrecy outage probability, and the probability of non-zero secrecy capacity for the primary network. Numerical results are provided to verify the correctness of the proposed analytical framework.

Secrecy performance of multi-user multi-hop cluster-based network with joint relay and jammer selection under imperfect channel state information

In this paper, we propose and analyze two important secure performance metrics of cluster-based multi-hop relay networks with friendly jamming nodes under the presence of multi-eavesdroppers in condition of imperfect channel estimation. At each hop, partial relay and jammer selection are used to improve the network security. The close-form expressions of secrecy outage probability and the probability of non-zero secrecy capacity of the considered system are derived as criteria to evaluate system security performance. The system performance is analyzed for Rayleigh fading channels with imperfect channel state information. Monte Carlo simulations are also performed to verify the correctness of the analytical results.

Secrecy Zone Achieved by Directional Modulation With Random Frequency Diverse Array

This work analyzes the impact of the transceivers' relative locations on the physical layer security achieved by directional modulation with a random frequency diverse array (DM-RFDA). Based on the adopted path loss model, we first derive the probability of non-zero secrecy capacity, denoted by pn, achieved at a legitimate receiver for an eavesdropper with a fixed location. We then examine how far we need to push the eavesdropper away from the transmitter in order to guarantee pn ≥ δ, where δ is a given value determining a certain level of security. The results reveal that the DM-RFDA system ensures a high level of security (e.g., δ = 0.95) for the legitimate user who is significantly further away from the transmitter than the eavesdropper. Furthermore, the results demonstrate that it is easier to guarantee the required level of security when there are more resource (e.g., higher bandwidth and a larger number of transmit antennas) in the DM-RFDA system.

Physical Layer Security Enhancement With Reconfigurable Intelligent Surface-Aided Networks

Reconfigurable intelligent surface (RIS)-aided wireless communications have drawn significant attention recently. We study the physical layer security of the downlink RIS-aided transmission framework for randomly located users in the presence of a multi-antenna eavesdropper. To show the advantages of RIS-aided networks, we consider two practical scenarios: Communication with and without RIS. In both cases, we apply the stochastic geometry theory to derive exact probability density function (PDF) and cumulative distribution function (CDF) of the received signal-to-interference-plus-noise ratio. Furthermore, the obtained PDF and CDF are exploited to evaluate important security performance of wireless communication including the secrecy outage probability, the probability of nonzero secrecy capacity, and the average secrecy rate. Monte-Carlo simulations are subsequently conducted to validate the accuracy of our analytical results. Compared with traditional MIMO systems, the RIS-aided system offers better performance in terms of physical layer security. In particular, the security performance is improved significantly by increasing the number of reflecting elements equipped in a RIS. However, adopting RIS equipped with a small number of reflecting elements cannot improve the system performance when the path loss of NLoS is small.

Secrecy Performance Analysis of Mixed α − μ and Exponentiated Weibull RF-FSO Cooperative Relaying System

Increasing concerns regarding wireless systems’ security are leading researchers to exploit the physical properties of a medium while designing any secured wireless network. The secrecy performance of a mixed radio frequency-free space optical (RF-FSO) system with a variable gain relaying scheme is investigated in this paper under the attempt of wiretapping by an eavesdropper. We assume that the eavesdropper can intrude the target data from the RF link only. Both the RF links (main and eavesdropper) undergo the $\alpha -\mu $ fading statistics and the FSO link experiences the exponentiated Weibull fading statistics. Exploiting the amplify-and-forward (AF) relaying scheme while considering two detection techniques (i.e. heterodyne detection and intensity modulation/direct detection) with pointing error impairments, the mathematical formulations of the unified probability density function and cumulative distribution function are performed for the equivalent signal-to-noise ratio of the considered dual-hop RF-FSO link. Closed-form analytical expressions for average secrecy capacity, secrecy outage probability, and the probability of non-zero secrecy capacity are derived in terms of Meijer’s $G$ and Fox’s $H$ functions to quantify the system performance. Capitalizing on these expressions, the secrecy performance is further analyzed for various channel parameters of RF links, aperture sizes of the receiver, pointing errors, and atmospheric turbulence severity. The results reveal that aperture averaging can improve the secrecy performance remarkably by suppressing the effects of turbulence. Monte Carlo simulations are provided to justify the accuracy of the proposed model.

Impact of antenna correlation on the physical layer security of cooperative relaying with OSTBC system

This study presents an analysis for evaluating the physical layer (PHY) security performance of a two-hop amplify-and-forward cooperative relaying system employing Alamouti orthogonal space–time block coding (OSTBC) in the presence of an eavesdropper, where the transmit antennas for OSTBC are assumed to be spatially correlated. It is also assumed that the authorised main channels as well as the non-authorised eavesdropper channels follow Rayleigh fading distribution. Closed-form mathematical expressions are derived for three performance metrics for evaluating the PHY security, namely the probability of non-zero secrecy capacity, the secrecy outage probability, and the average secrecy capacity. Using the extensive numerical results obtained from the derived mathematical expressions, the impact of antennas correlation on the PHY secrecy performance of the system is studied and evaluated under different parameters. It is also shown that the antennas correlation corresponding to the main channels has more impact than the antennas correlation corresponding to the eavesdropper channels.

Unified Framework for Secrecy Characteristics With Mixture of Gaussian (MoG) Distribution

The mixture of Gaussian (MoG) distribution was proposed to model the wireless channels by implementing the completely unsupervised expectation-maximization (EM) learning algorithm. With the high convenience for density estimation applications, the focus of this letter is supposed to investigate the secrecy metrics, including secrecy outage probability (SOP), the lower bound of SOP, the probability of non-zero secrecy capacity (PNZ), and the average secrecy capacity (ASC) from the information-theoretic perspective. The above-mentioned metrics are derived with simple and unified closed-form expressions. The effectiveness of our obtained analytical expressions are successfully examined and compared with Monte-Carlo simulations. One can conclude that this letter provides a simple but effective closed-form secrecy analysis solution exploiting the MoG distribution.

Physical layer security for multiuser multi‐eavesdropper multi‐input multi‐output (MIMO) system in the presence of imperfect feedback

SummaryIn this work, we analyze the physical layer security (PLS) for a multiuser (MUS) multi‐input multi‐output multi‐eavesdropper (MIMOME) wireless network using selection transmission (ST) at the base station (BS) with maximum ratio combining (MRC) at both of the receivers, receivers of legitimate users (LUs) as well as the receivers of illegitimate users over an uncorrelated Rayleigh fading channel. In this scenario, multiple users communicate to a BS at the same time multiple eavesdropper user may intercept the transmission. Next, we drive exact closed‐form expression for probability of nonzero secrecy capacity (PNZSC) and secrecy outage probability (SOP) in the presence of imperfect channel state information (ICSI). At last, we present the simulation results to authenticate the analytical results and analyze the impact of ICSI on PLS of MUS‐MIMOME system.

Secrecy Analysis Over Cascaded $\kappa -\mu$ Fading Channels With Multiple Eavesdroppers

In this paper, secrecy performance is investigated over the cascaded fading channel for the κ-μ distribution. The probability density function (PDF) and the cumulative distribution function (CDF) for the cascaded κ-μ fading channels as well as for some of its special cases, such as the Rayleigh and Rician fading channels are derived. A communication system operating over the cascaded κ-μ fading channel is analyzed in which the outage probability (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> ), the average symbol error probability (ASEP), and the average channel capacity (ACC) are obtained in terms of the Meijer G-function. In addition, the secrecy is examined for a system model where we have a transmitter, a receiver, and multiple colluding eavesdroppers attempting to overhear the information received. The secrecy performance is investigated in terms of the secrecy outage probability (SOP) and the probability of non-zero secrecy capacity (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nzc</sup> ). The analyses illustrate that increasing the number of eavesdroppers in the network degrades the secrecy of the system. Furthermore, increasing the cascade level in the channel degrades the system performance as well as the information security. In addition, the impact of the wiretap channel parameters and the average received signal-to-noise-ratio (SNR) at the eavesdroppers over the security are studied. To verify the accuracy of the derived analytical expressions, Monte-Carlo simulations are utilized.

Secrecy Performance Analysis of UAV Assisted Relay Transmission for Cognitive Network With Energy Harvesting

The unmanned aerial vehicle (UAV) assisted transmission can significantly improve the spectrum efficiency and coverage of the wireless communication network. The paper proposed a cooperative secrecy transmission mechanism, which can take advantage of transmitter signal of primary user (PU) as a dedicated radio frequency (RF) source with decode and forward (DF) UAV selection and energy harvesting (EH) under cognitive network. Specifically, the transmitting signal of PU in the cognitive network can be viewed and used as energy to drive secondary user (SU) nodes and multi-relay nodes to send signals. It was worth noting that the DF UAV relay may bring about the unexpected noise and decrease the received signal to noise ratio (SNR), therefore, the multiple UAV assisted relays selected with secrecy capacity maximization criteria under cognitive network was proposed and investigated in detail, where the destination node equipped with multiple antennas and adopted the optimal antenna selection receiver. Moreover, By using the function analysis method, the closed expressions of the system secrecy outage probability (SOP) and the probability of non-zero secrecy capacity were calculated and derived accurately. Furthermore, the asymptotic expressions of the UAV assisted relay system under the large SNR cases were analyzed in detail, where the expressions of secrecy diversity order and secrecy diversity gain of the UAV assisted relay cognitive system were obtained thoroughly. Simulation results verified the effectiveness of the proposed mechanism and the correctness of the calculation.

On the Physical Layer Security of Underlay Relay-Aided Device-to-Device Communications

In this paper, we study the underlay relay-aided Device-to-Device (D2D) communications to improve the physical layer (PHY) security of the cellular network. We propose a cooperative scheme, whereby the D2D pair, in return of being allowed to share the spectrum band of the cellular network, serves as a friendly jammer, through its multiple-input multiple-output relay, to degrade the wiretapped signal at an eavesdropper. This paper aims to show that spectrum sharing is advantageous for both D2D communications and cellular networks with respect to reliability and robustness for the former, and the physical layer security enhancement for the latter. To assess the proposed cooperative system model, closed-form expressions for the D2D outage probability, the secrecy outage probability, and the probability of non-zero secrecy capacity are derived. More importantly, the benefits due to the cooperation scheme are verified through numerical and simulation results.