System Secrecy Outage Probability Research Articles

A hybrid uplink-downlink secure transmission scheme for UAV-aided coordinated multi-point networks

Recognized as a pivotal facet in Beyond Fifth-Generation (B5G) and the upcoming Sixth-Generation (6G) wireless networks, Unmanned Aerial Vehicle (UAV) communications pose challenges due to limited capabilities when serving as mobile base stations, leading to suboptimal service for edge users. To address this, the collaborative formation of Coordinated Multi-Point (CoMP) networks proves instrumental in alleviating the issue of the poor Quality of Service (QoS) at edge users in the network periphery. This paper introduces a groundbreaking solution, the Hybrid Uplink-Downlink Non-Orthogonal Multiple Access (HUD-NOMA) scheme for UAV-aided CoMP networks. Leveraging network coding and NOMA technology, our proposed HUD-NOMA effectively enhances transmission rates for edge users, notwithstanding a minor reduction in signal reception reliability for strong signals. Importantly, the system's overall sum rate is elevated. The proposed HUD-NOMA demonstrates resilience against eavesdroppers by effectively managing intended interferences without the need for additional artificial noise injection. The study employs a stochastic geometry approach to drive the Secrecy Outage Probability (SOP) for the transmissions in the CoMP network, revealing superior performance in transmission rates and lower SOP compared to existing methods through numerical verification. Furthermore, guided by the theoretical SOP derivation, this paper proposes a power allocation strategy to further reduce the system's SOP.

Secrecy Performance Analysis of Mixed RF/FSO Systems Based on RIS Reflection Interference Eavesdropper

This paper proposes and studies the physical layer security of a mixed radio frequency/free space optical (RF/FSO) system based on reconfigurable intelligent surface (RIS)-aided jamming to prevent eavesdropping. This work considers Nakagami-m fading for the RF links and Málaga (M) turbulence for the FSO links. A two-hop decode-and-forward (DF) relaying method was used and the eavesdropper actively eavesdropped on the information transmitted by the RF link. The eavesdropper was thwarted by a wireless-powered jammer that transmits jamming signals, which were reflected by the RIS to the eavesdropper to ensure secure communication in the mixed RF/FSO system. The expressions of secrecy outage probability (SOP) and average secrecy capacity (ASC) of the RIS-aided mixed RF/FSO system were derived for the system model discussed above. The Monte Carlo method was utilized to verify the accuracy of these expressions. In the RIS-aided mixed RF/FSO system, the effects of the time switching factor, energy conversion efficiency, and average interference noise ratio on the system secrecy outage probability were analyzed and compared to the RIS-free mixed RF/FSO system. Meanwhile, the influence of the number of RIS reflecting elements, link distances before and after reflection, and fading severity parameter on the security performance of a mixed RF/FSO system assisted by RIS were also investigated.

Physical Layer Security Performance of Multi-User Mixed Radio-Frequency/Free-Space-Optics System Based on Optimal User Interference.

This paper presents research on the physical layer security performance of a multi-user mixed RF/FSO system based on optimal user interference. In this system model, the RF link experiences Rayleigh fading, and the FSO link follows the Fischer-Snedecor F distribution. The system adopts a double-hop-decode-and-forward (DF) relay scheme. We also consider the effect of directivity errors in the FSO link and assume the presence of an illegal eavesdropper with a single antenna near the RF link. The source node controls the energy collection and information forwarding using a multi-user structure based on simultaneous wireless information and power transfer (SWIPT). We select the optimal user to jam the eavesdropper's communication. We derive closed-form expressions for the mixed RF/FSO communication system's secrecy outage probability (SOP) and average secrecy capacity (ASC). Monte Carlo simulations are performed to verify the accuracy of these expressions. By formulating and simulating the simulation system, the impact of various important factors on the mixed system's physical layer security (PLS) is analyzed. The analysis indicates that increasing the number of antennas and interference signal-to-noise ratio (SNR) of the optimal user, the time allocation factor and energy conversion efficiency, and the improvement in the quality of atmospheric channels with improved weather will significantly enhance this system's PLS.

A Mixed FSO/RF Integrated Satellite-High Altitude Platform Relaying Networks for Multiple Terrestrial Users with Presence of Eavesdropper: A Secrecy Performance

In this paper, the secrecy performance of a mixed free space optical (FSO)/radio frequency (RF) integrated satellite-high altitude platform (HAP) relaying networks for terrestrial multiusers with the existence of an eavesdropper is investigated. In this network, FSO is adopted to establish the link between the satellite and HAP for which it experiences Gamma-Gamma distributions under different detection schemes (i.e., heterodyne and intensity modulation direct detection). The transmission between the amplify-and-forward (AF) relaying HAP and terrestrial multiusers is through the RF and is modeled as shadowed-Rician fading distribution. Owning to broadcasting nature of RF link, it is assumed that an eavesdropper attempts to intercept the users’ confidential message, and the eavesdropper link is subjected to Rician distributions. Specifically, the closed-form expression for the system equivalent end-to-end cumulative distribution function is derived by exploiting the Meijer’s G and Fox’s H functions. Based on this expression, the exact closed-form expressions of the system connection outage probability, secrecy outage probability, and strictly positive secrecy capacity are obtained under the different detection schemes at HAP. Moreover, the asymptotic analyze of the system secrecy outage probability is provided to obtain more physical insights. Furthermore, the accuracy of all the derived analytical closed-form expressions is verified through the Monte-Carlo simulations. In addition, the impact of atmospheric turbulence, pointing errors, shadowing severity parameters, and Rician factor are thoroughly evaluated. Under the same system conditions, the results depict that heterodyne detection outperforms the intensity modulation direct detection.

Secrecy Outage Performance Analysis of Cooperative NOMA Networks With SWIPT

In this letter, we investigate the secrecy outage performance of a cooperative non-orthogonal multiple access (NOMA) network, where a base station (BS) communicates with multiple cell-centre users and a cell-edge user in the presence of an eavesdropper. It is assumed that there is no direct link between the BS and the cell-edge user, and thus one of the cell-centre users is selected to act as a relay for the cell-edge user. Particularly, the selected cell-centre user adopts the simultaneous wireless information and power transfer (SWIPT) for decoding information and harvesting energy for forwarding. The closed-form approximate expression for the system secrecy outage probability is derived under the max-min user selection (MMUS) strategy. The theoretical results are verified by simulations, and it is shown that the MMUS strategy outperforms various benchmark strategies.

Secrecy outage probability analysis for RIS‐assisted NOMA systems

In this Letter, the physical layer security for a novel reconfigurable intelligent surface (RIS)-assisted non-orthogonal multiple access (NOMA) system in a multi-user scenario is investigated, where the authors consider the worst case that the eavesdropper also utilises the advantage of the RISs. More specifically, they derive analytical results for the secrecy outage probability (SOP). From the numerical results, they observe that the use of RISs can improve the secrecy performance compared to traditional NOMA systems. However, for the worst case that the received signals at the eavesdropper come from the RISs and source, increasing the number of intelligent elements on the RIS has a negative impact on the secrecy performance. At high signal-to-noise ratios, the system's SOP tends to a constant. Finally, the secrecy performance can be improved through group selection.

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 Security of Relay Assisted Cognitive Radio Networks in the Presence of Primary Transceiver Network

In this paper, the benefit of distinguishable diversity order within a co-operative relay system is exploited to overcome the problem of secure communication in an underlay wiretap cognitive radio network. This network is in a coexistence with a primary transceiver network and it is subjected to multiple eavesdropping attacks which employ a specific interception strategy. To improve the physical layer security, simple relay selection schemes will be proposed that aims at maximizing the minimum of the dual hop communication secrecy rates under primary network constraints. For Rayleigh fading channels, exact and asymptotic closed form expressions will be derived for the secondary system outage and secrecy rate. Furthermore, based on the network topology, tight inner and outer bounds will subsequently be derived on the system secrecy outage probability. By employing analytical and simulation results, the gain of the system diversity order is obviously investigated and emphasized.

Minimizing Secrecy Outage Probability in Multiuser Wireless Systems With Stochastic Traffic

We first extend the definition of the secrecy outage probability to wireless systems with adaptive transmission rates and secrecy rates. Then, we consider a scheduling problem in the aforementioned system, jointly considering the reliability, security, and stability, where the scheduler tries to allocate wireless resources to the legitimate users, stabilize the system, and minimize the secrecy outage probability. A stochastic network optimization framework is used to decompose the problem, and an online algorithm is proposed. We further consider a related problem, discuss the optimal solution, and show that the proposed algorithm cannot lead to optimal solution in some scenarios. By comparing the offline algorithm with our first algorithm, we further propose a second refined online algorithm, which is an optimal one. Extensive simulations are conducted to show the impact of the information arrival rate and the channel conditions on the system secrecy outage probability. These observations provide important insights and guidelines for the design and resource management of future wireless networks using secure communication technologies.

Multiuser untrusted relay networks with joint cooperative jamming and opportunistic scheduling under perfect and outdated CSI

A joint cooperative jamming and opportunistic scheduling (CJOS) scheme is proposed for a downlink multiuser relay network (MRN) with an untrusted fixed-gain amplify-and-forward relay. Specifically, the source's confident message is protected by employing CJ at the destinations and multiuser diversity is harvested via OS. Unified tight approximation and asymptotic expressions for the system secrecy outage probability with perfect/outdated channel state information (CSI) are derived. Our results explicitly show that with perfect CSI, CJOS scheme can improve the secrecy diversity order from 1/2 in single-user networks up to full diversity of 1 in MRNs. However, the outdated CSI degrades the secrecy diversity order from 1 to 1/2.