Expressions For Secrecy Outage Probability Research Articles

Secrecy Performance of Amplify-and-Forward Relay Networks with Relay Selection under Nakagami-m Fading

In this paper, we examine the secrecy outage performance of a dual-hop relay network under Nakagami-m fading. Here, we consider a three-terminal wireless communication system, where one node (source) communicates to the other node (destination) via a group of relay nodes. Due to severe fading and heavy shadowing, the direct link between two communicating nodes is not suitable to achieve the desired performance. Therefore, one relay is opportunistically selected amongst K relay nodes to establish their communications. For providing relay cooperation, the best relay is selected based on criteria that maximize the secrecy outage performance. Selected relay applies amplify-and-forward operation to facilitate relay assistance by broadcasting the received signal. Along with the destination node, an eavesdropper also receives the broadcasted signals. For this setup, we derive the closed-form expressions of secrecy outage probability with the assumption that wireless channels experience Nakagami-m fading. Various numerical results are illustrated to highlight the key performance impact of different system and channel parameters. We also verify the accuracy of our derived expressions by comparing the results with similar work done in the literature.

Relay and Jammer Selection Scheme in Wireless Networks with the Statistical Information of Multiple Eavesdropping Channels

Abstract Physical layer security (PLS) based on cooperative communication has been regarded as a promising technique to enhance the system security. In this paper, considering the statistical information of multiple eavesdropping channels, we investigate the security performance of cooperative relay and jammer selection scheme based on maximizing secrecy capacity (SC), where an optimal relay is selected to assist the source transmission, and the selected jammer is used to transmit the interference signal to suppress the eavesdroppers. Furthermore, the asymptotic expression of secrecy outage probability (SOP), a fundamental metric in the research of physical layer security, is derived. Finally, simulation results validate the security performance of the proposed scheme, and give some significant insights into the network security.

Selection of Jammer and Analysis on Secrecy Outage Probability for WANETs

Abstract In this paper, we investigate the physical layer security (PLS) in wireless ad hoc networks (WANETs). For fixed transmission distance model, we introduce the jammer selection scheme to enhance the secrecy transmission capacity. The jammer can prevent the eavesdropper from stealing information by sending the interference signal to the eavesdropper, thereby improving the security of the system. Based on the probability density function (PDF) and cumulative distribution function (CDF) of a random variable, we establish the expression of secrecy outage probability (SOP), a main metric in PLS. Finally, simulated results validate the effectiveness of selecting the appropriate jammer and theoretical analysis.

Secrecy Outage Analysis Over Random Beamforming Transmission With User Scheduling: Collusion vs. Exclusion

In this letter, we study the interacting effects of the exclusion zone and eavesdropper colluding strategy on the secrecy performance of multiple-antenna transmission system. In particular, a base station (BS) applies random beamforming and user scheduling to enhance the legitimate user channel while multiple eavesdroppers try, either individually or jointly, to overhear the transmitted signal. We derive the closed-form expressions of secrecy outage probability (SOP) of the system with and without exclusion zone under different colluding strategies. Through selected numerical examples, we develop the design guideline on the size of the exclusion zone for a target security level subject to eavesdroppers’ density and colluding strategy.

Secure Transmission Designs for NOMA Systems Against Internal and External Eavesdropping

The key idea of non-orthogonal multiple access (NOMA) is to serve multiple users in the same resource block to improve the spectral efficiency. Whereas due to the resource sharing, a security flaw of NOMA emerges in the presence of internal untrusted users, especially untrusted near users who are closer to the base station and can easily access the confidential information for paired far users. To mitigate the flaw, in this paper, we investigate the reliable and secure transmission of NOMA systems with untrusted near users, and propose joint beamforming and power allocation (JBP) scheme for the scenario. Meanwhile, from security point of view, we extend to a worse-case scenario where both untrusted near users and external eavesdroppers exist, and propose joint artificial noise aided beamforming and power allocation (JANBP) scheme to achieve a reliable and secure transmission for the scenario. The exact and asymptotic closed-form expressions of secrecy outage probability (SOP) for the two scenarios are derived to evaluate the secrecy performance achieved by the proposed schemes, respectively. The analysis and simulation results show the superiority of the proposed JBP and JANBP schemes in terms of combating internal and external eavesdropping, and also indicate the two schemes can achieve the same SOP at high SNR.

Secrecy Outage Probability and Fairness of Packet Transmission Time in a NOMA System

In this paper, we analyze the secrecy outage probability (SOP) and the fairness of average packet transmission time for a non-orthogonal multiple access (NOMA) system which consists of a base station (BS) and two legal NOMA users in the presence of an eavesdropper (Eve). In order to extract the superimposed signal, the Eve is considered in two modes, i.e., successive interference cancellation (SIC) mode and parallel interference cancellation (PIC) mode. Accordingly, we analyze the secrecy performance of the considered system by deriving a new exact expression for SOP. Furthermore, the optimal power allocation between two legal users is determined such that the average transmission time from BS to two legitimate users are approximately equal to achieve the fairness of average packet transmission time. Monte Carlo simulations are provided to verify our analytical results.

Physical-Layer Security Enhancement via Relay-Aided D2D Communications Underlaying Cellular Networks

In this paper, we propose a relay-assisted device-to-device (D2D) communication as an underlay in a cellular network, where two sequential best relay nodes based on different selection criteria are chosen. Novel analytical expressions of the secrecy outage probability (SOP) and the probability of nonzero secrecy capacity (PNSC) are derived to evaluate the secrecy performance of the cellular network. In addition, we derive a simple and explicit approximation of the SOP in the high signal-to-noise ratio (SNR) to gain some insights on how various system parameters affect the aforementioned secrecy performance. Also, for the sake of comparison, the analytical SOP expression when only the cellular network exists, i.e., without the interference of the D2D communication, is obtained. Furthermore, to assess the usefulness of the cooperation between the D2D communication and the cellular network, we derive an analytical expression for the mutual outage probability (MOP) which represents the true outage probability across both the cellular and D2D networks. An asymptotic analysis of the MOP in the high SNR regime is obtained and the diversity order is derived. Finally, our proposed mathematical framework is compared with Monte-Carlo simulations to verify the accuracy of the derivations.

Secrecy Outage Performance of Opportunistic Relay Selection With Limited CSI Feedback

Opportunistic relay selection is an important approach to enhance physical layer secrecy of relaying networks, but that severely depends on the obtained CSIs. In this letter, we study the impact of limited CSI feedback on the secrecy performance of cooperative decode-and-forward (DF) relay networks with opportunistic relay selection. We first derive the exact closed-form expression for the secrecy outage probability (SOP), and the asymptotic expression for SOP in the high signal-to-noise ratio (SNR) region. Then, based on the derived expressions, we evaluate the impact of limited CSI feeback on secrecy outage probability and secrecy diversity order. Numerical results show that the secrecy diversity order is 2, regardless of the number of feedback bits. However, increasing the number of feedback bits can improve the secrecy outage performance.

Secrecy outage probability of inter‐vehicular cognitive radio networks

SummaryHerein, we consider an underlay cognitive radio network (CRN) where mobile secondary user wishes to transmit a confidential information to the secondary destination in the presence of an illegitimate eavesdropper which is trying to steal the classified message signal. The proposed scenario can be viable for a secondary safety task force working with a primary regiment, which wishes to transmit the confidential information to the commander while an eavesdropper is trying to intercept the classified information. In the analysis, two novel power allocation methods are considered by assuming perfect and limited feedback channels of the primary network, and for both methods, exact and asymptotic expressions of secrecy outage probability (SOP) are derived for N*Nakagami‐m fading channels which are used to model fading channels such as mobile‐to‐mobile/vehicle‐to‐vehicle communication systems where the nodes are moving into a rich scattering environment. We further verified our analytic results through Monte‐Carlo simulations. It is shown from the numerical results that the cascading degree of the channels has a worsening effect on the secrecy outage performance of the CRN systems.

Jammer-Aided Secure Communications for Cooperative NOMA Systems

This letter investigates a jammer-aided cooperative non-orthogonal multiple access (NOMA) system, where one relay is used to deliver information and other relays are acted as jammers. Two simple relay selection (RS) strategies, e.g., random RS and max-min RS, are considered in this letter. Analytical and asymptotical expressions for secrecy outage probability (SOP) under both RS schemes are developed. Simulation results show that NOMA system with jammer achieves a lower SOP than the one without jammer in the moderate to high SNR range. Moreover, by adopting max-min RS strategy, the secrecy outage performance can be further improved in the low SNR region, while still tends to a constant in high SNR region.

Physical-Layer Security Analysis over M-Distributed Fading Channels

In this paper, the physical layer security over the M-distributed fading channel is investigated. Initially, an exact expression of secrecy outage probability (SOP) is derived, which has an integral term. To get a closed-form expression, a lower bound of SOP is obtained. After that, the exact expression for the probability of strictly positive secrecy capacity (SPSC) is derived, which is in closed-form. Finally, an exact expression of ergodic secrecy capacity (ESC) is derived, which has two integral terms. To reduce its computational complexity, a closed-from expression for the lower bound of ESC is obtained. As special cases of M-distributed fading channels, the secure performance of the K, exponential, and Gamma-Gamma fading channels are also derived, respectively. Numerical results show that all theoretical results match well with Monte-Carlo simulation results. Specifically, when the average signal-to-noise ratio of main channel is larger than 40 dB, the relative errors for the lower bound of SOP, the probability of SPSC, and the lower bound of ESC are less than 1.936%, 6.753%, and 1.845%, respectively. This indicates that the derived theoretical expressions can be directly used to evaluate system performance without time-consuming simulations. Moreover, the derived results regarding parameters that influence the secrecy performance will enable system designers to quickly determine the optimal available parameter choices when facing different security risks.

Dispersed beamforming approach for secure communication in UDN

Wireless communication systems are prone to many security breaches due to open nature of the medium and exponential a rise in subscribers. Hence, physical layer security (PLS) has emerged as one of the dominant low complexity alternatives to overcome the impact of eavesdropping by managing the physical characteristics of the medium. In this paper, we ensure PLS to moving users which tends to experience rise in handover, as a result of proximity between users and base station. This study is based on ultra-dense network (UDN). To tackle this challenge, novel secure beamforming named as beam broadening and beam merging have been proposed. Besides, we propose a synchronization approach called synchronized mobility clustering for UDN to reduce the overheads generated due to the exchange of information about moving users. More specifically, we derive an analytical expression for secrecy outage probability—an important security metric. The effect of proposed approaches have been validated through numerical results and the results show the effectiveness of the proposed approaches against eavesdropping. Finally, the performance of the proposed scheme is evaluated and compared with the conventional beamforming approach. However, this proposed approach works well for a varied density of users and location to be targeted.

Secrecy Analysis in DF Relay Over Generalized-$K$ Fading Channels

In this paper, we analyze the secrecy performance of the decode-and-forward (DF) relay system in generalized- $K$ fading channels. In a typical four-node communications model, a source ( $S$ ) sends confidential information to a destination ( $D$ ) via a relay ( $R$ ) using DF strategy in two time slots, while an eavesdropper ( $E$ ) wants to overhear the information from $S$ to $D$ over generalized- $K$ fading channels. To be more realistic, we assume that $E$ can receive the signals of two time slots, and there is no direct link between $S$ and $D$ because of heavy fading. Based on those assumptions, we derive closed-form expressions for the secrecy outage probability (SOP) and ergodic secrecy capacity (ESC) by using a tight approximate probability density function of the generalized- $K$ model. Furthermore, asymptotic expressions for the SOP and ESC are also derived in the high signal-to-noise ratio region, not only because we can get some insights about SOP and ESC, but also because expressions for SOP and ESC can be simplified significantly. The single relay system is subsequently extended into a multi-relay system, where the asymptotic SOP analysis of three proposed relay selection strategies is investigated. Moreover, the security-reliability tradeoff analysis in the multi-relay system is also presented given that $S$ adopts a constant code rate. Finally, the Monte-Carlo simulation is used to demonstrate the accuracy of the derived closed-form expressions.

On the secrecy outage probability and performance trade-off of the multi-hop cognitive relay networks

We study the physical-layer security of multi-hop secondary network under spectrum sharing constraint caused by the primary, which consists of many simultaneously independent direct transceiver pairs. The existence of a secondary eavesdropper, which attempts to hear confidential information, results in secure communication to be needful. The PUs’ interference forces low secondary SIRs. The secondary power constraint according to PUs causes the QoS to diminish, especially when the PUs transmission simultaneously operates. In this paper, we derive the closed-form of end-to-end multi-hop secrecy outage probability expression with independent non-identically distributed (i.n.i.d) Rayleigh fading. Furthermore, the secondary intercept probability is derived. Combining the outage probability, we present the security-reliability of the system. Besides, the impact of different numbers of primary transceivers on end-to-end multi-hop outage probability is investigated. Finally, our theoretical results verified via extensive Monte Carlo simulations.

Physical layer security of hybrid satellite‐terrestrial relay networks with multiple colluding eavesdroppers over non‐identically distributed Nakagami‐ m fading channels

This study investigates the physical layer security of a downlink hybrid satellite-terrestrial relay network (HSTRN) where the satellite channel follows shadowed-Rician fading and terrestrial channels are assumed to undergo independent and non-identically distributed Nakagami- m fading. Herein, the authors consider a multi-antenna satellite, which communicates with a terrestrial user via an amplify-and-forward relay in the presence of multiple colluding eavesdroppers at the earth. They derive novel expressions of secrecy outage probability (SOP), ergodic secrecy capacity, and probability of positive secrecy capacity for the proposed network. They further obtain the achievable secrecy diversity order of the considered HSTRN by employing asymptotic analysis of SOP expression. Finally, numerical and simulation results are provided to validate the accuracy of the proposed analysis and to highlight the impact of a multi-antenna satellite on future wireless systems.

Secrecy Analysis for Cooperative NOMA Networks With Multi-Antenna Full-Duplex Relay

In a downlink non-orthogonal multiple access (NOMA) system, the reliable transmission of cell-edge users cannot be guaranteed due to severe channel fading. On the other hand, the presence of eavesdroppers can severely threaten the secure transmission due to the open nature of wireless channel. Thus, a two-user NOMA system assisted by a multi-antenna decode-and-forward relay is considered in this paper, and a two-stage jamming scheme, full-duplex-jamming (FDJam), is proposed to ensure the secure transmission of NOMA users. In the FDJam scheme, using full-duplex, the relay transmits the jamming signal to the eavesdropper while receiving confidential messages in the first stage, and the base station generates the jamming signal in the second stage. Furthermore, we eliminate the self-interference and the jamming signal at the relay and the legitimate node, respectively, through relay beamforming. To measure the secrecy performance, analytical expressions for secrecy outage probability (SOP) are derived for both the cell-center and cell-edge users, and the asymptotic SOP analysis at high transmit power is presented as well. Moreover, two benchmark schemes, half-duplex-jamming and full-duplex-no-jamming, are also considered. Simulation results are presented to show the accuracy of the analytical expressions and the effectiveness of the proposed scheme.

A Simple Evaluation for the Secrecy Outage Probability Over Generalized-K Fading Channels

A simple approximation for the secrecy outage probability (SOP) over generalized-K fading channels is developed. This approximation becomes tighter as the average signal-to-noise ratio (SNR) of the wiretap channel decreases. Based on this simple expression, we also analyze the asymptotic SOP in the high SNR region of the main channel. Besides simplifying the SOP expression significantly, this asymptotic SOP expression reveals the secrecy diversity order in a general case. Numerical results demonstrate the high accuracy of our proposed approximation results.

Physical‐layer security for cellular multiuser two‐way relaying networks with single and multiple decode‐and‐forward relays

AbstractWe investigate the secrecy performance of cellular multiuser two‐way relay networks, where the bidirectional information exchange between a multiantenna base station (BS), and several users can be accomplished with the assistance of decode‐and‐forward relay(s) in the presence of a multiantenna passive eavesdropper. We employ low‐complexity antenna selection strategy at the BS coupled with user scheduling for maximizing the end‐to‐end signal‐to‐noise ratios (SNRs). To enhance the wiretap probability, the eavesdropper applies a maximal ratio combining technique to combine the received signals. Under such considerations, in the single‐relay scenario, we deduce the exact closed‐form secrecy outage probability (SOP) expression under Rayleigh fading channels. For more insights into the system secrecy diversity order, we derive the closed‐form asymptotic SOP expressions at high SNR based on the quality of the main and wiretap links. In the multirelay scenario, we formulate an opportunistic relay selection strategy, followed by its impact on the SOP performance in the presence of Rayleigh channels. To show the impact of multiple relays on the secrecy diversity order, we derive the asymptotic SOP expressions in the high SNR regime depending on the quality of the main and wiretap links. It is shown from the asymptotic SOP expressions under both single‐relay and multirelay scenarios that the secrecy diversity order reduces to zero in the high SNR regime, regardless of number of antennas, number of users, and number of relays. Our results also reveal that the SOP performance diminishes with an increased number of eavesdropper antennas. Numerical and simulation results verify our derived analytical findings.

On Secure QoS-based NOMA Networks with Multiple Antennas and Eavesdroppers over Nakagami-m Fading

In this paper, we study the physical layer security of a downlink multi-input single-output non-orthogonal multiple access (NOMA) system, in which transmit antenna selection (TAS) scheme, users’ quality of service (QoS) requirements, Nakagami-m fading channel, and user selection solution are considered for secure NOMA transmission. Specifically, we investigate the scenario that a base station (BS) (source) communicates with two legitimate user (LU) clusters with different priority depending on their QoS requirements in the presence of multiple passive eavesdroppers over Nakagami-m fading. To enhance the secrecy performance, we examine a TAS scheme and a user selection method. In this context, prior to transmission, a transmit antenna and a user in high-priority LU cluster are jointly selected to maximize the channel quality of the link from the BS to the selected user. Furthermore, together with the selected high-priority user, a user in low-priority LU cluster, which has the best channel condition, is chosen for performing two-user NOMA. In order to evaluate the secrecy performance, tight and asymptotic closed-form expressions of secrecy outage probability for selected LUs and overall system are derived. Our theoretical results confirmed by Monte–Carlo simulation show that in QoS-based NOMA system, high-priority users cause the higher effects on the overall secrecy performance in comparison with low-priority users. Finally, these results also indicate that our proposed communication protocol achieves the secrecy performance greater than conventional protocol.

Secrecy Analysis in SWIPT Systems Over Generalized-$K$ Fading Channels

In this letter, we investigate the secrecy performance of the simultaneous wireless information and power transfer (SWIPT) system over generalized- $K$ fading channels. After analyzing the communications scenario, we derive the closed-form expression for the secrecy outage probability (SOP), and give some simplified expressions for SOP in some special cases. Effective secrecy throughput is also investigated to capture the amount of secure transmitted information. To derive the diversity order, the asymptotic SOP is also analyzed when the average signal-to-noise ratio is sufficiently large. Finally, numerical results are used to validate the correctness of our derived expressions.