The physical layer security performances of low-complexity opportunistic transmission strategy based on multiple antenna are investigated for cooperative adaptive decode-and-forward relaying system in Nakagami-m fading channels. To fully utilize the antenna diversity gain to improve the system security performance, the transmitting nodes apply the transmit antenna selection strategy, and the receiving nodes apply the maximal ratio combining strategy. The closed-form expressions of secrecy outage probability are derived, the asymptotic analysis of secrecy performance is further provided, and the secrecy diversity order are also obtained. Simulation results verify the correctness of theoretical analysis and identify the effects of several system parameters on the secrecy performance of the opportunistic transmission strategy. It is shown that the system secrecy performance can be greatly improved by increasing the number of antennas at the legitimate nodes and increasing the Nakagami fading channel parameters of legitimate channels.
The physical layer security performances of low-complexity opportunistic transmission strategy based on multiple antenna are investigated for cooperative adaptive decode-and-forward relaying system in Nakagami-m fading channels. To fully utilize the antenna diversity gain to improve the system security performance, the transmitting nodes apply the transmit antenna selection strategy, and the receiving nodes apply the maximal ratio combining strategy. The closed-form expressions of secrecy outage probability are derived, the asymptotic analysis of secrecy performance is further provided, and the secrecy diversity order are also obtained. Simulation results verify the correctness of theoretical analysis and identify the effects of several system parameters on the secrecy performance of the opportunistic transmission strategy. It is shown that the system secrecy performance can be greatly improved by increasing the number of antennas at the legitimate nodes and increasing the Nakagami fading channel parameters of legitimate channels.
This paper investigates secure cooperative transmissions in a dual-hop MIMO relay system using a combined transmit antenna selection (TAS) and maximal-ratio combining (MRC) scheme over the Nakagami-m fading channels, where an adaptive decode-and-forward relaying protocol and an multi-antenna eavesdropper are considered. Due to the feedback delay, channel state information (CSI) for TAS might be outdated at both the source and the relay. To evaluate the secrecy performance of the TAS/MRC scheme and the impacts of outdated CSI, the closed-form expressions for the metrics of exact ergodic secrecy rate and exact secrecy outage probability are derived under both perfect and outdated CSI conditions in a channel feedback error model. In order to explicitly reveal the behaviors of the secrecy performance in high signal-to-noise ratio regime, asymptotic expressions for both the metrics are further derived. As validated by simulation results, analytically numerical results demonstrate that outdated the CSI always results in a loss in the secrecy performance, but the loss can be recovered by increasing the number of antennas at legitimate receivers. Furthermore, the outdated CSI yields a reduced secrecy diversity order, whereas only the perfect CSI leads to the full secrecy diversity order.
This Paper presents a comprehensive analysis of secrecy performance in a multicast wireless communication network operating over Nakagami- 0.5 fading channels. The Probability of non-zero secrecy multicast capacity (PNSMC) and the secure outage probability for multicasting (SOPM) are analytically developed under the influence of multiple relays, legitimate users, and eavesdroppers. To ensure enhanced secrecy reliability, an opportunistic relay selection approach is integrated with selection combining (SC) diversity at the destination. Verified the analytical results through extensive Monte Carlo simulations, exhibiting a strong correspondence with theoretical predictions. Numerical evaluations indicate that an increased number of relays and destination antennas notably strengthen secrecy performance, whereas stronger eavesdropper channels deteriorate it. In general, the framework presented provides useful design guidelines for cooperative secure multicast communication systems operating in severe fading environments.
In this paper, we investigate the performance of cooperative amplify-and-forward (AF) multi-relay networks with relay selection strategy over independent and identically distributed (i.i.d.) Nakagami-m fading channels. In this system we study multiuser cooperative relaying to have a secure transmission from source to destination, since transmitted information may be wiretapped by multiple eavesdroppers. The secrecy outage probability is derived in closed-form using signal-to-noise-ratio statistics, while a useful expression is presented for the asymptotically low outage regime. Our results explicitly demonstrate significant improvement of the secrecy outage probability in the multi-relay scenario.
Transmit beamforming is a diversity technique in multiple-input multiple-output (MIMO) systems. It improves the diversity order and enhances the information security of the MIMO systems. In this paper, we mathematically analyze the secure performance of a MIMO decode-and-forward (DF) relay system under the presence of an eavesdropper and with the imperfect channel state information (CSI) of the eavesdropping channel. To enhance the secrecy performance, we employ multiple antennas at all legitimate nodes and utilize two linear beamforming schemes, i.e., maximal ratio transmission (MRT) and transmission zero-forcing (TZF), at the transmitter and maximal ratio combining (MRC) scheme at the receiver. The probability density function (PDF) of the output SNR for different numbers of antennas at the transmitter and receiver is plotted and discussed. After that, we apply this PDF to derive the closed-form expressions of the secrecy outage probability (SOP) and ergodic secrecy capacity (ESC) of the considered MIMO-DF relay system over Rayleigh fading channels for MRT/MRC and TZF/MRC schemes. In addition, based on the obtained analysis results, we provide the location of the relay that minimizes the system SOPs. All the analysis results are validated by Monte-Carlo simulations. The results show that the TZF/MRC scheme provides better SOP and ESC than the MRT/MRC scheme. Moreover, the number of antennas at the legitimate nodes and the location of the eavesdropper significantly impact the secrecy performance.
Joint Relay and Eavesdropper Selection Strategy Against Multiple Eavesdroppers over Nakagami-m Fading Channels in Cooperative Decode-and-Forward Relay Networks
Physical layer security (PLS) in the presence of multiple eavesdroppers over Nakagami-m fading channels for cooperative decode-and-forward (DF) relay network that consists of one source, one destination, and multiple relays is investigated. Different from the recent PLS system model that only considers one eavesdropper during eavesdropping attack, this paper extends the one-eavesdropper case to a multiple-eavesdropper scenario and investigates joint relay and eavesdropper selection (JRES) strategy against eavesdropping attack over Nakagami-m fading channels. In the proposed strategy, the best relay is selected via the maximum relay forward channel capacity. In addition, since eavesdroppers are noncooperative, the worst case is considered. Namely, the wiretap channel between the best relay and the chosen eavesdropper has the maximum capacity. Traditional direct transmission and opportunistic relay selection (ORS) scheme in the presence of one eavesdropper over Rayleigh channel are regarded as benchmarks. Moreover, a security-reliability tradeoff (SRT) performance is analyzed, where the reliability performance is expressed by outage probability (OP), while the security performance is measured by intercept probability (IP). Closed-form expressions of OP and IP are derived. The numerical results show that the proposed JRES scheme outperforms the traditional direct transmission and the ORS scheme in the presence of one eavesdropper over Rayleigh channel. The SRT performance is enhanced obviously with the increasing of relay numbers and Nakagami channel fading factor m for a given number of eavesdroppers, which extends the PLS and SRT performance analysis to a more general case in a cooperative DF relay network.
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( ) in terms of SOP, and in terms of intercept probability, where and 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.