We study opportunistic decode-and-forward relaying transmission in cooperative cluster-based wireless sensor networks (WSNs) with secrecy constraints, where a passive eavesdropper may overhear the source message. To deal with this problem, we consider the novel opportunistic relay section cooperative transmission for the cluster configuration of WSNs. The system performance in terms of the secrecy outage probability and the probability of nonzero secrecy capacity are analyzed and the exact closed-form expressions are derived over Rayleigh fading channels. Furthermore, we derive the asymptotic secrecy outage probability which accurately reveals the secrecy diversity order. Finally, numerical results are presented to verify the theoretical analysis and depict that node cooperation has a great potential to enhance physical layer security against eavesdropping.
We study opportunistic decode-and-forward relaying transmission in cooperative cluster-based wireless sensor networks (WSNs) with secrecy constraints, where a passive eavesdropper may overhear the source message. To deal with this problem, we consider the novel opportunistic relay section cooperative transmission for the cluster configuration of WSNs. The system performance in terms of the secrecy outage probability and the probability of nonzero secrecy capacity are analyzed and the exact closed-form expressions are derived over Rayleigh fading channels. Furthermore, we derive the asymptotic secrecy outage probability which accurately reveals the secrecy diversity order. Finally, numerical results are presented to verify the theoretical analysis and depict that node cooperation has a great potential to enhance physical layer security against eavesdropping.
In this study, we deal with a cooperative wireless communications system of security constraints in which there is no knowledge about channel state information (CSI) of the eavesdropper. In order to improve the tradeoff between security and reliability, we opportunistically employ relays via an incremental and selective cooperation with respect to the CSI of the main link. In this cooperation, named as opportunistic cooperative transmission (OCT), the first priority is communication through the direct link as far as possible. However, a relay that has the best link to the main destination is employed for retransmitting the source information when the direct link is so weak which cannot provide a specific quality. In fact, since improving the reliability of the favorable communications by use of the relays increases the risk of successful interception by the eavesdropper at the same time, the OCT scheme tries to avoid excess of rebroadcasting the secret information by the relays whenever the direct link is strong enough; otherwise it employs an opportunistically selected relayed link. Hence, it can improve the security for a specific level of reliability and vice versa. We derive closed-form expressions for the security-reliability tradeoff (SRT) and secrecy outage probability (SOP) of the OCT scheme. Moreover, we provide asymptotic analyses which are illustrative on the security behavior of the proposed scheme. Finally, simulation results are presented which confirm validity of the analysis and reveal the desired performance of OCT in terms of both SRT and SOP.
Abstract Cooperative communication has emerged as a pivotal innovation in wireless networks, allowing multiple sites with single antennas to collaborate in signal transmission, thereby improving power efficiency, enhancing spatial diversity, and increasing the reliability of signal reception. This paper introduces a cooperative communication system comprising two communicating nodes, multiple relays, and an eavesdropper. The eavesdropper attempts to intercept the signals transmitted between the two nodes. To mitigate this threat, a jamming signal is employed as artificial interference, degrading the quality of the wiretap channel and preventing the eavesdropper from successfully acquiring the transmitted data, thereby enhancing system security. The α−μ α - μ fading distribution is utilized as a generalized model for wireless channel fading. The system model is analyzed, and closed-form expressions for secrecy outage probability are derived for single-relay and the asymptotic secrecy outage probability is derived for multiple-relay scenarios, and finally the probability of the correct computation of the secrecy packets is evaluated. Analytical results are provided to substantiate the theoretical outcomes.
In this paper, we present a comprehensive investigation on the secrecy performance of opportunistic relay selection systems employing the decode-and-forward protocol over Rayleigh fading channels. Considering a practical setting where direct link between the source node (Alice) and the destination node (Bob) is available, we study the secrecy performance of three different diversity combining schemes, namely, maximum ratio combining (MRC), distributed selection combining (DSC), and distributed switch-and-stay combining (DSSC). Throughout the analysis, we consider two different scenarios based on the availability of the eavesdropper's channel state information (CSI), i.e., Scenario A, where the eavesdropper's CSI is not available at Alice and the relay, and Scenario B, where Alice and the relay have knowledge about the eavesdropper's CSI. For Scenario A, we derive exact closed-form expressions for secrecy outage probability and simple asymptotic approximations for the secrecy outage probability, which enable the characterization of the achievable secrecy diversity order and coding gains. For Scenario B, we derive closed-form expressions for the achievable secrecy rates. For both scenarios, we investigate the impact of feedback delay (outdated CSI) on the secrecy performance wherein exact and asymptotic secrecy outage probability and closed-form expressions of the secrecy achievable rates are obtained. Our analytical findings suggest that both the MRC and DSC schemes achieve the maximum diversity order of K+1 where K is the number of relays. In addition, the feedback delay has a significant impact on the achievable secrecy performance by reducing the achievable diversity order to two.
In this paper, we investigate the physical layer security of a dual-hop cooperative network in the presence of a full-duplex active eavesdropper, which can overhear the confidential signals and transmit jamming signals simultaneously. We utilize the optimal relay selection scheme to improve the secrecy performance, where the relay maximizing the secrecy capacity will be selected to forward the information. To evaluate the secrecy performance of our system, we derive a compact closed-form expression of the secrecy outage probability. Besides, we also analyze the asymptotic performance related to the position of the nodes. Finally, we verify our analysis through the numerical results, and demonstrate that there exists a secrecy protection region where the secrecy outage probability is below a target probability.
This paper investigates the security at the physical layer in cooperative wireless networks (CWNs) where the data transmission between nodes can be realised via either direct transmission (DT) or relaying transmission (RT) schemes. Inspired by the concept of physical-layer network coding (PNC), a secure PNC-based modify-and-forward (SPMF) is developed to cope with the imperfect shared knowledge of the message modification between relay and destination in the conventional modify-and-forward (MF). In this paper, we first derive the secrecy outage probability (SOP) of the SPMF scheme, which is shown to be a general expression for deriving the SOP of any MF schemes. By comparing the SOPs of various schemes, the usage of the relay is shown to be not always necessary and even causes a poorer performance depending on target secrecy rate and quality of channel links. To this extent, we then propose an opportunistic secure transmission protocol to minimise the SOP of the CWNs. In particular, an optimisation problem is developed in which secrecy rate thresholds (SRTs) are determined to find an optimal scheme among various DT and RT schemes for achieving the lowest SOP. Furthermore, the conditions for the existence of SRTs are derived with respect to various channel conditions to determine if the relay could be relied on in practice.