We investigate a relay network where the source can potentially utilize an unauthenticated amplify-and-forward (AF) relay to augment its direct transmission of a confidential message to the destination. Since the relay is unauthenticated, it is desirable to protect the confidential data from it while simultaneously making use of it to increase the reliability of the transmission. We study the likelihood of achieving simultaneously secure and reliable message transmission via the secrecy outage probability (SOP) of the relay network. We first characterize the SOP for three different schemes: direct transmission, conventional AF relaying, and cooperative jamming. Subsequently, an asymptotic analysis is conducted to determine the optimal policies for different power budgets and channel gains. Numerical results are presented to verify the theoretical predictions of the preferred transmission policies from a secrecy outage perspective.
We investigate a relay network where the source can potentially utilize an unauthenticated amplify-and-forward (AF) relay to augment its direct transmission of a confidential message to the destination. Since the relay is unauthenticated, it is desirable to protect the confidential data from it while simultaneously making use of it to increase the reliability of the transmission. We study the likelihood of achieving simultaneously secure and reliable message transmission via the secrecy outage probability (SOP) of the relay network. We first characterize the SOP for three different schemes: direct transmission, conventional AF relaying, and cooperative jamming. Subsequently, an asymptotic analysis is conducted to determine the optimal policies for different power budgets and channel gains. Numerical results are presented to verify the theoretical predictions of the preferred transmission policies from a secrecy outage perspective.
We investigate the secrecy outage performance for a cooperative unauthenticated relay network where antenna selection is employed at the multi-antenna relay. Both traditional amplify-and-forward (AF) relaying and a cooperative jamming (CJ) protocol are studied. We characterize the exact secrecy outage probability (SOP) for the AF scheme, and analyze the asymptotic behaviour in terms of SOP for the CJ scheme. Although both the unauthenticated relay and the destination perceive diversity gain from antenna selection, we show that as the number of antennas grows, the SOP approaches one for AF, while it approaches zero for CJ. For a fixed number of antennas, we demonstrate that the CJ scheme is better than AF relaying for high SNR, and its SOP approaches zero when the SNR goes to infinity. The theoretical analysis is also validated via several numerical examples.
We investigate a relay network where the source can potentially utilize an untrusted non-regenerative relay to augment its direct transmission of a confidential message to the destination. Since the relay is untrusted, it is desirable to protect the confidential data from it while simultaneously making use of it to increase the reliability of the transmission. We first examine the secrecy outage probability (SOP) of the network assuming a single antenna relay, and calculate the exact SOP for three different schemes: direct transmission without using the relay, conventional non-regenerative relaying, and cooperative jamming by the destination. Subsequently, we conduct an asymptotic analysis of the SOPs to determine the optimal policies in different operating regimes. We then generalize to the multi-antenna relay case and investigate the impact of the number of relay antennas on the secrecy performance. Finally, we study a scenario where the relay has only a single RF chain which necessitates an antenna selection scheme, and we show that unlike the case where all antennas are used, under certain conditions the cooperative jamming scheme with antenna selection provides a diversity advantage for the receiver. Numerical results are presented to verify the theoretical predictions of the preferred transmission policies.
Considering a nonregenerative untrusted relay network, we investigate three different secure transmission strategies, for example, noncooperative strategy, conventional amplify-and-forward (AF) strategy, and cooperative jamming (CJ) strategy. To thoroughly assess the secrecy performance achieved by the three strategies, we derive the closed-form expressions for the connection outage probability and secrecy outage probability regarding each strategy. Based on these expressions, the reliability and security tradeoff (RST) is examined to facilitate the design of the transmitting parameters. We then present the closed-form expression for the effective secrecy throughput (EST) and characterize the overall efficiency of these transmission strategies. Furthermore, we conduct the asymptotic analysis for the secrecy throughput, which enables us to determine the optimal transmission strategy under different scenarios. Our analytical and numerical results demonstrate that compared with the noncooperative and AF strategies, the CJ strategy possesses the best performance in terms of RST. Additionally, we also find that the EST performance of the AF strategy is nearly invariable when the quality of the second hop changes.
In this paper, the secrecy outage performance of a three-node amplify-and-forward relay network with an untrustworthy relay is investigated. To enable a secure transmission, we consider a destination-based jamming technique to prevent the relay from successfully decoding the secret messages between the source and the destination. In addition, the relay is assumed to be an energy-constrained device, thus being first energized by the source in order to be able to retransmit the information to the destination. In doing so, a time switching-based simultaneous wireless information and power transfer scheme is used. A closed-form asymptotic expression for the secrecy outage probability is derived in order to obtain a tight approximation at medium-to-high signal-to-noise ratio. The accuracy of the performed analysis is corroborated by Monte Carlo simulations through different illustrative cases. Numerical results show the impact of key system parameters on the secrecy performance, such as the time allocation factor between the energy harvesting and information transmission phases, the power allocation factor between source and destination for cooperative jamming, and the relay position, so as to provide insights on the design criteria for energy efficient and secure networks.
In this paper, we investigate the secrecy performance of a dual-hop cooperative untrusted relay network. In this network, a source node communicates with the destination node via an untrusted fixed-gain amplify-and-forward (AF) relay node. We use destination-assisted jamming so as to keep the source and destination nodes information confidential from the relay node. Under this scenario, we derive the exact secrecy outage probability (SOP) expression, tight approximate SOP expression, and asymptotic SOP expression in the high signal-to-noise ratio regime under Nakagami-m fading channels. The analysis studied in this paper can be applicable to any AF relaying systems for fixed relay gain, and two scenarios to calculate the fixed gain are compared in terms of SOP performance. Finally, the numerical and simulation studies corroborate our analytical findings.
We study the secrecy outage probability of the amplify-and-forward (AF) relaying protocol, which consists of one source, one destination, multiple relays, and multiple eavesdroppers. In this system, the aim is to transmit the confidential messages from a source to a destination via the selected relay in presence of eavesdroppers. Moreover, partial relay selection scheme is utilized for relay selection based on outdated channel state information where only neighboring channel information (source-relays) is available and passive eavesdroppers are considered where a transmitter does not have any knowledge of eavesdroppers’ channels. Specifically, we offer the exact secrecy outage probability of the proposed system in a one-integral form as well as providing the asymptotic secrecy outage probability in a closed-form. Numerical examples are given to verify our provided analytical results for different system conditions.