Terms Of Secrecy Outage Probability Research Articles

Secrecy Analysis of Underlay CRN in the Presence of Correlated and Imperfect Channel

The presence of correlated and imperfect channel state information (CSI) affects the secrecy performance of cognitive radio networks (CRN). In this paper, we propose a physical layer security analysis of underlay CRN in terms of secrecy outage probability (SOP), average secrecy rate (ASR), and amount of secrecy loss (ASL). Closed forms of SOP, ASR, and ASL are provided over imperfect CSI of Rayleigh fading environment where the legitimate channel is correlated with the eavesdropper channel. The analytical results are compared with the simulation results. The work is also compared with existing work. It has been observed that the secrecy performance of the network improves as peak interference power increases, and the correlation positively impacts the secrecy performance at a medium-to-high signal-to-noise ratio (SNR); however, it degrades the data security capability of the network at low SNR. Furthermore, asymptotic analysis shows that the secrecy performance of the network improves with the growing correlation between legitimate and eavesdropper channels when the SNR of the legitimate channel is much higher than that of the eavesdropper channel, whereas secrecy performance decreases with a reducing correlation when the SNR of the legitimate channel is approximately equal to SNR of eavesdropper channel.

Secure Swarm UAV-Assisted Communications With Cooperative Friendly Jamming

This article proposes a cooperative friendly jamming framework for swarm unmanned aerial vehicle (UAV)-assisted amplify-and-forward (AF) relaying networks with wireless energy harvesting. Due to the limited energy of the UAVs, we develop a collaborative time-switching relaying protocol which allows the UAVs to collaborate to harvest wireless energy, relay information, and jam the eavesdropper. To evaluate the secrecy rate, we derive the secrecy outage probability (SOP) for two popular detection techniques at the eavesdropper, i.e., selection combining and maximum-ratio combining. Monte Carlo simulations are then used to validate the theoretical SOP derivation and to show the effectiveness of the proposed framework in terms of SOP as compared with the conventional amplify-and-forward relaying system. Using the derived SOP, one can obtain engineering insights to optimize the energy harvesting time and the number of UAVs in the swarm to achieve a given secrecy protection level. The analytical SOP derived in this work can also be helpful in future UAV secure-communications optimizations (e.g., trajectory, locations of UAVs). As an example, we present a case study to find the optimal corridor to locate the swarm so as to minimize the system SOP.

Secrecy performance analysis for a NOMA based FSO-RF system with imperfect CSI

In this paper, we consider a non-orthogonal multiple access (NOMA) based mixed free space optical–radio frequency (FSO-RF) system with imperfect channel state information (CSI) and evaluate the secrecy performance in terms of secrecy outage probability (SOP). Specifically, a source ( S ) first forwards an optical NOMA signal to a relay ( R ) via an FSO link, and then R performs an optical–electrical conversion and broadcasts the converted signal to users over the RF links. Both the FSO and RF links are incorporated with the NOMA technique, and the CSI imperfection in both links is considered. Assuming both users have multiple antennas, and adopting the maximal ratio combining diversity schemes, we derive the analytical and asymptotic expressions for SOP when the FSO link undergoes gamma–gamma fading with pointing error and the RF links are subject to Rayleigh fading. In addition, both decode-and-forward and amplify-and-forward protocols are taken into account and compared. Monte Carlo simulations are also used to verify the accuracy of the derived results.

3-D Stochastic Geometry-Based Modeling and Performance Analysis of Efficient Security Enhancement Scheme for IoT Systems

Internet of Things (IoT) systems are becoming core building blocks for different services and applications supporting every day’s life. The heterogeneous nature of IoT devices and the complex use scenarios make it hard to build secure and private IoT systems. Physical-layer security (PLS) can lead to efficient solutions reducing the impact of the increasing security threats. In this work, we propose a new PLS-based IoT transmission scheme that offers a highly secured transmission probability, low-computational complexity, and reduced power consumption. We utilize 3-D stochastic geometry to model a more realistic IoT system and test our proposed scheme in different practical scenarios, where sensors, access points (APs), and eavesdroppers are randomly located in 3-D space. We focus on the system performance, in terms of secrecy outage probability (SOP) and secured successful transmission probability (SSTP), using tight closed-form expressions. An optimization problem is developed to deduce the optimal sensors’ transmit power, the APs’ density, and the maximum number of transmission tentative, when maximizing the SSTP. The proposed scheme outperforms the baseline retransmission scheme, in terms of SOP and SSTP based on analytical and simulation results.

Guest editorial: Smart communications and networking: architecture, applications, and future challenges

Guest editorial: Smart communications and networking: architecture, applications, and future challenges

Secrecy performance of transmit antenna selection for underlay MIMO cognitive radio relay networks with energy harvesting

In this paper, the secrecy performance in a MIMO cognitive radio (CR) relay network with energy harvesting (EH) and transmit antenna selection/maximal ratio combining (TAS/MRC) is invstigated, where the DF relaying protocol and multiple colluding passive eavesdroppers are considered. To improve the security of wireless transmission, two antenna selection schemes are proposed, namely, the optimal transmit antenna selection (OTAS) scheme and suboptimal transmit antenna selection (STAS) scheme. For the purpose of comparison, the space-time transmission (STT) scheme is introduced as a baseline. The exact and asymptotic closed-form secrecy outage probability (SOP) expressions for OTAS, STAS and STT schemes are derived over Rayleigh fading channels. An extension of the TAS framework to an artificial noise (AN) aided MIMO network is further presented and an AN aided transmit antenna selection (AN-TAS) scheme is proposed, in which the unselected antennas at R are used to emit AN for interfering with Es. Numerical results show that the OTAS and STAS schemes perform better than STT scheme in terms of SOP. Meanwhile, the SOP of AN-TAS scheme is much smaller than that of OTAS, STAS and STT schemes in the high SNR region, indicating the benefit of applying AN in MIMO network.

Security-Reliability Tradeoffs for Dual-Hop Satellite Communication Systems with AF Relaying Protocol

Satellite communication systems serve as an indispensable component of heterogeneous wireless networks in the next generation era for providing various critical civil and military applications. However, due to the broadcast nature and full accessibility of the wireless medium, such systems exist serious security threats. As an effort to address this issue, this paper, for the first time, investigates secure communication in a dual-hop communication system consisting of a satellite working as an amplified-and-forward relay. We first provide the theoretical modeling to analyze the fundamental system metrics in terms of secrecy outage probability and connection outage probability. By using the modeling, we then study the security-reliability tradeoffs and propose to transmit power schemes depending on the search algorithm. We further analyze asymptotic expressions of outage performance, which was further utilized to simplify the transmit power schemes. Simulation results show the validation of the proposed secure transmission model and design schemes of transmit power. Results also illustrate that transmit power schemes based on asymptotic analysis effectively achieve the optimal performance for the relay satellite communication system.

On secrecy performance for IoT enabled SWIPT multi-relaying NOMA systems

In this paper, we evaluate the secrecy performance in terms of secrecy outage probability (SOP) for Internet of things (IoT) enabled multi-relaying non-orthogonal multiple access (NOMA) networks with energy harvesting over Nakagami-m fading channels. Specifically, we consider the scenario that a power-constrained source and N(N⩾1) IoT relays first harvest energy from a dedicated power beacon under a time switching mode, and then the source sends a confidential information to a legitimate user via a selected IoT relay, which forwards the decoded signal together with its own information data under a NOMA protocol to two legitimate users in the presence of an eavesdropper. Moreover, a two-stage relay selection criterion is also adopted to enhance the system’s secrecy performance. As a benchmark, we also adopt a random relay selection scheme to analyze the secrecy performance. To clearly reveal the benefits of our proposed schemes, the analytical expressions for SOP under those two schemes have been obtained and validated through Monte-Carlo simulations.

Secure transmission for cooperative NOMA systems with source‐relay selection

Both cooperative non-orthogonal multiple access (NOMA) and physical layer security (PLS) are promising techniques for future communication systems. This paper investigates the PLS performance of a cooperative NOMA system where multiple sources transmit a superposed message to two users by utilizing either amplify-and-forward (AF) or decode-and-forward (DF) relays in both non-colluding and colluding eavesdropper scenarios. A source-relay selection scheme is proposed for this system aiming at improving the secrecy performance. Additionally, the closed-form expression of the secrecy outage probability (SOP) is derived for the proposed source-relay selection schemes. It is demonstrated that in the proposed schemes, the theoretical results match well with the simulation results. In addition, the proposed schemes outperform the conventional OMA system in terms of SOP.

Robust Hybrid Precoding Design for Securing Millimeter-Wave IoT Networks Under Secrecy Outage Constraint

Hybrid precoding architecture, as a cost-effective approach for millimeter-wave (mmWave) communications, can achieve an excellent tradeoff between spectrum efficiency and hardware implementation complexity. However, the design of a robust hybrid precoding for improving the physical layer security (PLS), which is insensitive to the uncertainty of eavesdropper's channel state information (CSI), has not been well studied. This article for the first time designs a probabilistically robust hybrid precoding scheme for securing broadcast communications in Internet of Things (IoT) with eavesdropper's imperfect CSI. Specifically, considering the Gaussian CSI error model, we maximize the minimum secrecy rate of multiple IoT devices (IoDs) by jointly designing analog and digital precoders under the constraints in terms of secrecy outage probability and per IoD's information rate. The optimization problem is challenging due to the coupling of the analog and digital precoders, and the secrecy outage constraint. To handle these challenges, we first employ a conservative probability inequality to transform the secrecy outage probability constraint into a deterministic one. Then, by employing the penalty dual decomposition (PDD) method, we develop a novel iterative algorithm to convert the resultant nonconvex problem into a sequence of convex problems, which can guarantee the convergence to its Karush-Kuhn-Tucker (KKT) solution. Simulation results show that the proposed algorithm can achieve significant secrecy performance gains compared with the benchmark algorithm.

Secrecy outage probability analysis of energy‐aware relay selection for energy‐harvesting cooperative systems

The secrecy outage performance for a cooperative cognitive radio energy-harvesting network is analyzed. The cognitive network is composed of an energy-constrained cognitive source (CS), multiple energy-constrained cognitive relays (CRs) and a cognitive destination (CD) as well as an eavesdropper (E) coexists with a primary network consisting of a primary transmitter (PT) and a primary receiver (PR). The CS and CRs are equipped with energy harvesters for collecting energy from the radio frequency signal from PT and their transmit powers are limited by the interference threshold at PR. To prevent confidential information leaking to E, an optimal relay selection (ORS) scheme and a suboptimal relay selection (SRS) scheme are proposed. In ORS scheme, the whole channels state information (CSI) of wireless links is available to CRs while SRS only needs to know the CSI of main channels from CRs to CD. Moreover, the closed-form expressions of secrecy outage probabilities for both ORS and SRS schemes are derived. For the purpose of comparison, the classical round-robin relay selection (RRRS) is also analyzed in terms of secrecy outage probability. Furthermore, the numerical results show that ORS achieves the best performance and RRRS performs the worst in terms of secrecy outage probability.

Secrecy Outage Probability of Energy-Harvesting Cooperative NOMA Transmissions With Relay Selection

Three relay selection techniques, aiming at achieving secure non-orthogonal multiple access in cooperative energy-harvesting (EH) communications, are proposed and compared. In the cooperative relaying system, the source node communicates with multiple users through amplify-and-forward EH relays in the presence of a passive eavesdropper. The relay selection is a two-stage strategy, where the first stage aims at achieving the users’ target data rate, and the second aims at optimizing the secrecy outage probability. New explicit analytical expressions for the secrecy outage probability are derived for three operating scenarios: i) when the channel state information (CSI) of the eavesdropper is unknown, and a two-stage conventional relay selection scheme is considered, ii) when CSI of the eavesdropper is known, and a two-stage optimal relay selection scheme is used, and iii) when multiple relays participate in forwarding the signal to the end users. Monte-Carlo simulations are provided to confirm the derivations, and the effects of the main system parameters on its secrecy are investigated. In particular, it is shown that the optimal relay selection scheme outperforms the conventional and the multiple-relays schemes in terms of secrecy outage probability, and that this superiority becomes more obvious when the number of the relays increases.

SECURITY CAPABILITY ANALYSIS OF COGNITIVE RADIO NETWORK WITH SECONDARY USER CAPABLE OF JAMMING AND SELF-POWERING

This paper investigates a cognitive radio network where a secondary sender assists a primarytransmitter in relaying primary information to a primary receiver and also transmits its own information toa secondary recipient. This sender is capable of jamming to protect secondary and/or primary informationagainst an eavesdropper and self-powering by harvesting radio frequency energy of primary signals.Security capability of both secondary and primary networks are analyzed in terms of secrecy outageprobability. Numerous results corroborate the proposed analysis which serves as a design guidelineto quickly assess and optimize security performance. More importantly, security capability trade-offbetween secondary and primary networks can be totally controlled with appropriate selection of systemparameters.

Secrecy Outage Analysis of Transmit Antenna Selection Assisted With Wireless Power Beacon

This paper considers a multiple-input-multiple-output (MIMO) energy-harvesting (EH) system, which is made up of a source (S) and a destination (D) as well as an eavesdropper (E). In this system, S, D and E are equipped with multiple antennas and S can be charged by a power beacon (PB) in the EH phase of the total communication process. To enhance the physical-layer security, we propose optimal antenna selection (OAS) scheme and suboptimal antenna selection (SAS) scheme, relying on whether the global channel state information (CSI) is available or unavailable to S. Moreover, the analysis of the conventional space-time transmission (STT) is carried out as a baseline. In order to intuitively show the effect of the number of antennas on secrecy outage performance, the secrecy diversity analysis for STT, SAS and OAS schemes is carried out through the asymptotic secrecy outage probability as the MER (the average gains between main channel from S to D and wiretap channel from S to E) tends to infinity. Additionally, the results show that the secrecy diversities of STT, SAS and OAS are the product of the number of antennas at S and D, which has no relation to E. Furthermore, the research findings indicate that our proposed OAS scheme performs the best in terms of secrecy outage probability and STT scheme achieves the worst secrecy performance.

Physical layer security in space‐time block codes from coordinate interleaved orthogonal design

In this study, the physical layer (PHY) security performance of orthogonal space-time block coding (OSTBC) employing a coordinate interleaved orthogonal design (CIOD) is analysed and investigated using two metrics: average secrecy capacity and secrecy outage probability. It is shown that the CIOD system is superior than OSTBC in terms of secrecy outage probability. Closed-form expressions for PHY security metrics in OSTBC as well as CIOD are presented and compared. Then, an extended model of CIOD with arbitrary number of antennas is considered. Furthermore, the effects of artificial noise and imperfect channel estimation on PHY security of OSTBC and CIOD systems are investigated. The validity of theoretical expressions is verified by simulation, and it is shown that in practical cases the CIOD system has a better secrecy outage performance than that of the OSTBC system.

Secrecy Analysis for Multi-Relaying RF-FSO Systems With a Multi-Aperture Destination

In this paper, we investigate the physical layer security for an asymmetric dual-hop radio frequency-free space optical (RF-FSO) communication system, in which a source transmits information to a multi-aperture destination (D) through a best relay under the wiretapping of a multi-aperture eavesdropper (E). The best relay is selected by a partial relay selection scheme in terms of maximum instantaneous channel gain for the RF link. Moreover, equal gain combining scheme is also used to process the multiple copies of receiving signal at D and E. Assuming all the RF channels are subject to independent and identical distributed (i.i.d.) Nakagami-m fading and all the FSO channels are modeled by i.i.d. Gamma-Gamma process, the secrecy performance in terms of secrecy outage probability and the probability of strictly positive secrecy capacity are studied, and the accuracy of the analytical results is verified by Monte-Carlo simulations.

Secure Transmission in Cognitive Wiretap Networks with Full-Duplex Receivers

This paper studies the secure transmission in the dual-hop cognitive wiretap networks, where the secondary transmitter (Alice) aims to transmit confidential information to the secondary receiver (Bob) in the face of a multi-antenna relay (Relay), while the malicious eavesdropper (Eve) is used to eavesdrop the confidential information from Alice and Relay. To improve security, we design two transmission schemes, namely maximal-ratio combining/maximal-ratio transmission-selection combining (MRC/MRT-SC) with half-duplex (HD) receiver and maximal-ratio combining-zero forcing beamforming/maximal-ratio transmission-selection combining-zero forcing beamforming (MRC-ZFB/MRT-SC-ZFB) with full-duplex (FD) receiver. To evaluate the secrecy performance obtained from the proposed schemes comprehensively, the new closed-form and simple asymptotic expressions for the secrecy outage probability (SOP) and secrecy throughput (ST) of our considered networks with MRC-ZFB/MRT-SC-ZFB and MRC/MRT-SC schemes are derived, respectively. Thus, we explore the effect of various schemes on system secrecy performance in terms of SOP and ST. Analytical results and numerical simulations demonstrate that MRC-ZFB/MRT-SC-ZFB achieves better performance in the two proposed schemes. In particular, we show that the FD receiver plays a crucial role in designing the cognitive wiretap networks for protecting the legitimate link against attack from the malicious eavesdropping.

Physical layer security in cooperative amplify‐and‐forward relay networks over mixed Nakagami‐ m and double Nakagami‐ m fading channels: performance evaluation and optimisation

The authors investigate the secrecy performance of a cooperative relaying network, wherein a fixed source communicates with a fixed destination via an amplify-and-forward mobile relay in the presence of a passive mobile eavesdropper. They assume that the source-to-relay channel and relay-to-destination channel experience Nakagami-m fading, whereas relay-to-eavesdropper link follows double Nakagami-m fading. Under such a mixed fading environment, they derive the novel tight closed-form expressions for the secrecy outage probability (SOP), probability of non-zero secrecy capacity, and intercept probability of the considered system. They also deduce the asymptotic secrecy outage and intercept probability expressions in the high signal-to-noise ratio regime to highlight the impact of fading parameters and channel conditions on the secrecy diversity order. It is shown that the system can achieve secrecy diversity order of min( m SR , m RD ) in terms of SOP, and m RD in terms of intercept probability, where m SR and m RD represent the fading severity parameters between source and relay and between relay and destination, respectively. They also formulate and investigate analytically two optimisation problems, namely, optimal relay location with fixed power allocation and optimal power allocation with fixed relay location, to minimise the system SOP. They verify analytical findings via numerical and simulation results.

Two-Way Secure Communication with Multiple Untrusted Half-Duplex AF Relays

In this paper, we analyze the secrecy outage probability (SOP) of a cognitive cooperative radio network in a two-way communication in which two secondary source communicate with each other via multiple untrusted half-duplex amplify and forward relays in the absence of direct link. Due to the cognitive scenario, power is allocated to secondary nodes on the basis of outage constraint of the primary network. In the absence of direct link between two sources, communication completes in two time slots. In the first time slot, both of the sources broadcast the information signal and in the second time slot, a selected relay broadcasts the amplified information signals of both of the sources. Relays being untrusted, they can eavesdrop the message from the information signal. A particular relay, which maximizes the end-to-end secrecy capacity, is selected to broadcast the signal. The selected untrusted relay can only eavesdrop the message and other relays forcefully remain in idle condition. At the untrusted relay, information signals of both of the sources act as a jamming to each other. The selected untrusted relay harvests the energy using a power splitting ratio scheme. We observe the performance of the proposed model in terms of SOP. We find the optimal values of energy harvesting factor at which SOP becomes minimum. Several important parameters such as the impact of number of untrusted relays, primary transmit power, peak transmit power of secondary sources, threshold outage rate of primary receiver and threshold secrecy rate on SOP is indicated. An analytical expression for the SOP has been developed in a single integration form. Numerical results based on analytical expression are verified by MATLAB simulation.

Energy-efficient secure multiuser scheduling in energy harvesting untrusted relay networks

In this paper, we investigate opportunistic secure multiuser scheduling in energy harvesting untrusted relay networks, where an energy-constrained amplify-and-forward (AF) relay harvests energy from the received radio frequency signal via using the power splitting protocol. To exploit the potential advantages (e.g., multiuser diversity and direct links) for secrecy improvement, we examine three opportunistic user scheduling schemes, i.e., optimal scheduling scheme, maximum scheduling scheme, and minimum scheduling scheme. Specifically, the optimal scheduling scheme performs user selection by maximizing the ratio between the signal-to-noise-ratio (SNR) at the destination and the corresponding SNR at the untrusted relay. The maximum scheduling scheme is conventional user selection that maximizes the channel gain of the direct links. For the minimum scheduling scheme, we try to reduce the overheard information at the untrusted relay by selecting the user with the lowest channel gain of the relay links. For these three schemes, we comprehensively examine the achievable secrecy performance including probability of positive secrecy rate, secrecy outage probability (SOP), asymptotic SOP, secrecy throughput (ST), as well as secure energy efficiency (SEE) to help facilitate an energy-efficient secure transmission design. Simulation results demonstrate that the maximum scheduling scheme outperforms the minimum scheduling scheme in terms of SOP at relatively low SNRs and target secrecy rates.