Multiple Non-colluding Eavesdroppers Research Articles

Improving secrecy performance of NOMA networks with multiple non-colluding eavesdroppers employing multiple aerial reconfigurable intelligent surfaces

This paper proposes exploiting multiple aerial reconfigurable intelligent surfaces (ARISs) for the secrecy performance enhancement of non-orthogonal multiple access (NOMA) networks. More specifically, multiple ARISs are deployed to aid two legitimate NOMA users when multiple non-colluding eavesdroppers (NCEs) also try to receive and detect the messages. Moreover, the transmitter-user paths are combined with the transmitter-ARIS-user paths at the users to increase the received message power. The mathematical expressions of secrecy outage probabilities (SOPs) of the proposed networks (referred to as the NOMA-ARIS networks) are derived over realistic Nakagami-m channels recommended for the fifth/beyond generations (5G/B5G) of wireless systems. In addition, the asymptotic expressions of SOPs in the high transmit power region are also provided. Numerical findings unequivocally indicate that the SOPs of the proposed NOMA-ARIS networks are significantly lower than those of the classical NOMA networks without ARISs. Moreover, the lowest SOPs of the proposed NOMA-ARIS networks are achieved faster than those of the classical NOMA networks. Consequently, utilizing ARISs can significantly reduce the transmit power and dramatically improve the secrecy performance of NOMA networks. On the other hand, some valuable recommendations are discussed after deeply investigating the effects of crucial parameters such as the number of reflecting elements (REs) in ARISs, secrecy target rate, position of NCEs, fading order, and power allocation coefficients on the SOPs of the proposed NOMA-ARIS networks.

Physical Layer Secrecy Performance Analysis of Jamming-Assisted Overlay Cognitive NOMA Networks With Hardware Impairments and Multiple Non-Colluding Eavesdroppers

Physical Layer Secrecy Performance Analysis of Jamming-Assisted Overlay Cognitive NOMA Networks With Hardware Impairments and Multiple Non-Colluding Eavesdroppers

Secure transmission in one-bit cell-free massive MIMO system with multiple non-colluding eavesdroppers

Secure transmission in one-bit cell-free massive MIMO system with multiple non-colluding eavesdroppers

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.

Secrecy Outage Performance of FD-NOMA Relay System With Multiple Non-Colluding Eavesdroppers

In this paper, we investigate the secrecy performance of a full-duplex (FD) non-orthogonal multiple access (NOMA) relay system under the presence of multiple non-colluding eavesdroppers over Rayleigh fading channels. Furthermore, to improve legitimate link's capacity, the partial relay selection (PRS) scheme is applied to choose the best relay. To evaluate the secrecy performance, we derive the closed-form expressions of the secure outage probability (SOP) of each user, the overall SOP and the sum effective secrecy throughput (EST) of the considered FD-NOMA relay system. We compare the SOP of the FD-NOMA relay system with that of the half-duplex (HD)-NOMA system and the SOPs of FD-NOMA relay system in the cases that PRS and multiple-relay (MR) schemes are employed at multiple relays. Monte-Carlo simulations verify the correctness of all derived mathematical expressions. Numerical results show that thanks to utilizing FD relays and PRS scheme, the considered FD-NOMA relay system has superior secrecy performance than other systems. Furthermore, increasing the number of FD relays, enhancing their self-interference cancellation capability, and selecting a suitable transmission power help to reduce the SOP of the considered FD-NOMA relay system. Meanwhile, the EST rapidly increases with the equivocation rate of the eavesdropping channel then gradually reaches the saturated maximum value.

Enhancing physical layer security via a UAV friendly jammer for NOMA‐based IoT systems with imperfect CSI

AbstractIn this article, we investigate physical layer security in downlink Internet of Things networks under imperfect channel state information (CSI), in which a controller (Alice) intends to serve two user devices (D1 and D2) simultaneously by using nonorthogonal multiple access (NOMA). Cooperative jamming (CJ) is introduced as a powerful solution for guaranteeing secure transmission. To be specific, we integrate an unmanned aerial vehicle (UAV) jammer that generates artificial noise to confuse multiple noncolluding eavesdroppers (Eves). Considering only D1 requires secure transmission, we develop an adaptive power allocation scheme to maximize the secrecy rate at D1 while meeting the desired quality of service (QoS) threshold at D2. Furthermore, a strategy can be utilized to obtain the optimal location of the UAV jammer is derived for further performance enhancement. Besides, we also examine the impact of the channel uncertainties on system performance. Numerical results are provided to confirm the superiority and applicability of the proposed CJ scheme over benchmark schemes in terms of secrecy performance and effective energy efficiency.

Secrecy Performance Analysis of Air-to-Ground Communication With UAV Jitter and Multiple Random Walking Eavesdroppers

Flexible mobility and random jitter are two unique features of UAV communication platforms. Although advantages of mobility have been extensively explored, the random jitter of UAV platforms, caused by airflow and body vibrations, has been rarely studied. This work aims to answer the two fundamental questions: i) how to analyze the secrecy performance when considering UAV jitter and ii) can this inherent characteristic of UAV be exploited to enhance secrecy? Detailed, we study the modeling and analysis of UAV jitter on the secrecy performance in an air-to-ground (A2G) wiretap system with multiple non-colluding eavesdroppers, where a UAV-mounted transmitter equipped with directional antennas illuminates ground terminals in a finite area. Random waypoint model is applied to characterize the mobility of eavesdroppers. To be specific, by modeling UAV jitter in both horizontal azimuth and vertical elevation, distortion and shift of UAV illumination area are analyzed. Further, beam-illumination probability of a randomly located ground terminal is obtained. Following which, a tractable framework for analyzing the secrecy coverage probability (SCP) and ergodic secrecy capacity (ESC) is developed. Expressions for SCP and ESC are derived with characterizations for the signal-to-noise ratio received at legitimate receiver and eavesdroppers. Finally, extensive simulations are provided to validate the theoretical analysis. This is the first work to find that UAV jitter can be exploited to enhanced secrecy performance of A2G wiretap system with appropriate UAV height and beamwidth.

Cooperative Secure Transmission in MISO-NOMA Networks

In this paper, we investigate cooperative secure transmission in non-orthogonal multiple access (NOMA) networks where a source (Alice) intends to transmit confidential messages to one legitimate user with high-level security requirement (LU1), and serve another normal one (LU2) simultaneously. In order to enhance the transmission security, a cooperative jammer (Charlie) is employed to confuse multiple non-colluding eavesdroppers (Eves). Taking both secrecy outage restriction of LU1 and the desired quality of service (QoS) requirement of LU2 into consideration, we propose an adaptive power allocation strategy for maximizing secrecy rate. Numerical results are provided to validate that our proposed scheme significantly outperforms the conventional NOMA secure transmission scheme.

Secure communications with untrusted relays: a multi‐pair two‐way relaying approach

Physical-layer security is usually ensured by the injection of artificial noise (AN) at the legitimate source or destination when relays are cooperative but untrusted. In this work, in order to avoid the power-consuming AN at the legitimate user pairs, the authors investigate multi-pair two-way relaying as a solution for secure transmission in wireless relay networks with untrusted relays. They formulate a generalised problem for the joint design of cooperative beamforming (CB) and AN at relays to maximise the secrecy sum-rate in wireless networks with multi-pair legal users, multiple untrusted relays as well as multiple non-colluding eavesdroppers. Further, they reformulate, approximate and relax the original non-convex problem into a sequence of convex sub-problems based on semi-definite relaxation (SDR) and Taylor series approximation. Particularly, for the reformulated problem they prove that the SDR is in fact tight, and hence propose an iterative algorithm for CB and AN design at the relays. In the simulations, they demonstrate the fast convergence and high achievable secrecy sum-rate of the proposed algorithm. Also, they simulate and discuss the impact of the number of user pairs on the secrecy sum-rate, and reveal the change of performance gain with the number of multiple user pairs.

On the security of cooperative cognitive radio networks with distributed beamforming

This paper investigates the secrecy performance of amplify-and-forward (AF)-relaying cooperative cognitive radio networks (CCRNs) over Rayleigh-fading channels. Specifically, we consider practical passive eavesdropping scenarios, where the channel state information of the eavesdropper’s link is not available at the secondary transmitter. In order to avoid interfering with the primary receiver and enhance the secrecy performance, collaborative distributed beamforming is adopted at the secondary relays. Closed-form and asymptotic expressions for the secrecy outage probability of CCRNs in the presence of single and multiple non-colluding eavesdroppers are derived. The asymptotic analysis reveals that the achievable secrecy diversity order of collaborative distributed beamforming with M AF relays is M−1 regardless of the number of eavesdroppers. In addition, simulations are conducted to validate the accuracy of our analytical results.

Artificial-Noise Aided Secure Transmission in Large Scale Spectrum Sharing Networks

We investigate beamforming and artificial noise generation at the secondary transmitters to establish secure transmission in large scale spectrum sharing networks, where multiple noncolluding eavesdroppers attempt to intercept the secondary transmission. We develop a comprehensive analytical framework to accurately assess the secrecy performance under the primary users’ quality of service constraint. Our aim is to characterize the impact of beamforming and artificial noise generation (BF&AN) on this complex large scale network. We first derive exact expressions for the average secrecy rate and the secrecy outage probability. We then derive an easy-to-evaluate asymptotic average secrecy rate and asymptotic secrecy outage probability when the number of antennas at the secondary transmitter goes to infinity. Our results show that the equal power allocation between the useful signal and artificial noise is not always the best strategy to achieve maximum average secrecy rate in large scale spectrum sharing networks. Another interesting observation is that the advantage of BF&AN over BF on the average secrecy rate is lost when the aggregate interference from the primary and secondary transmitters is strong, such that it overtakes the effect of the generated AN.

A Closed-Form Power Allocation for Minimizing Secrecy Outage Probability for MISO Wiretap Channels via Masked Beamforming

In this letter, we aim to achieve secure communication for a multiple-input single-output (MISO) wiretap channel in the presence of multiple non-colluding eavesdroppers. It is assumed that the eavesdroppers' channels are unavailable to the transmitter, and artificial noise (AN) is used to provide masked beamforming for degrading the eavesdroppers' channels. First, we derive the secrecy rate outage probability for the masked beamforming system and then the optimal power allocation between data and AN is obtained in closed form for minimizing the secrecy rate outage probability under a total power constraint. The effects of the number of transmit antennas, the transmit power, and the target secrecy rate on the optimal power allocation parameter are characterized. Numerical results are presented to show the performance of our proposed power allocation scheme.