This letter studies the problem of secure communication for a dual-hop energy harvesting (EH) relay network in the presence of multiple eavesdroppers. An adaptive cooperative jamming (ACJ) scheme is proposed, which can adaptively adjust power allocation factor to maximize the secrecy rate in practical networks where there is no eavesdroppers' channel-state-information (CSI). To evaluate the performance of the proposed scheme, we analyze the ergodic secrecy capacity (ESC) of multi-antenna networks using the ACJ, and derive the closed-form expressions of the ESC for large antenna systems. Simulation results show that the proposed scheme outperforms the benchmark scheme.
This letter studies the problem of secure communication for a dual-hop energy harvesting (EH) relay network in the presence of multiple eavesdroppers. An adaptive cooperative jamming (ACJ) scheme is proposed, which can adaptively adjust power allocation factor to maximize the secrecy rate in practical networks where there is no eavesdroppers' channel-state-information (CSI). To evaluate the performance of the proposed scheme, we analyze the ergodic secrecy capacity (ESC) of multi-antenna networks using the ACJ, and derive the closed-form expressions of the ESC for large antenna systems. Simulation results show that the proposed scheme outperforms the benchmark scheme.
A two-hop relay network is considered, in which an eavesdropper can overhear the relaying signal. To prevent the eavesdropper from decoding this signal, a destination transmits a jamming noise while a source transmits the data signal to the relay. At the same time, the relay can harvest energy from both the source signal and the jamming noise, and use this harvested energy to forward the received signal to the destination. In such a wireless-powered relay system with cooperative jamming, we propose two adaptive relaying schemes based on power splitting and time switching techniques. In the proposed power splitting-based relaying (PSR) and time switching-based relaying (TSR) schemes, the relay controls the power splitting ratio (p) and time switching ratio (α), respectively, in order to achieve a balance between signal processing and energy harvesting. We find analytically the optimal values of p and α in each scheme to maximize the secrecy capacity under the assumption of high signal-to-noise ratio (SNR). Interestingly, although the eavesdropper's channel state information (CSI) is used in the derivation of the optimal control parameters (p and α), they are shown not to be affected by the eavesdropper's CSI in a high SNR regime. This implies that the proposed schemes can be effective even for practical environments where there is no eavesdropper's CSI. Furthermore, simulation results show that they well coincide with the exact solutions in practical environments even though the closed-form solutions are obtained with a high SNR assumption. Moreover, the comparisons of PSR and TSR in various scenarios show that the two relaying schemes have complementary performances depending on the network conditions. Specifically, PSR achieves greater secrecy capacity than TSR when the channel condition is unfavorable to the eavesdropper for wiretapping.
This paper investigates the secrecy performance of amplified-and-forward (AF) relay wiretap model by using energy harvesting (EH) and signal alignment technique. All nodes equipped with multi antennas play different roles in terms of source, destination, relay, eavesdropper and jamming node. The jamming node designs artificial noise based on signal alignment principle, and then transmits it to the eavesdropper with harvested energy. Due to different power limitations, we propose power allocation schemes called Local Power Constraints scheme (LPCS) and Global Power Constraints scheme (GPCS), which maximize the secrecy rate of the system and obtain better secrecy performance when compared with the non-EH scheme and the partial nodes power allocation EH scheme. Furthermore, we also analyze the effect of the energy harvesting on the secure degrees of freedom (SDOF) in the high signal-to-noise (SNR) region, and simulate the secrecy performance with convex optimization method by proving the convexity of the optimization problem. Results show that the proposed schemes outperform the compared schemes on the secrecy performance, and achieve more secrecy rate when the destination and the relay have more antennas.
Abstract In this paper, for energy harvesting (EH) two‐way relay (TWR) networks with two‐sided eavesdroppers, the problem of secure information transmission is investigated. Based on this system model, a novel full‐duplex (FD) relaying jamming scheme is proposed to achieve simultaneously information reception, EH and jamming signal transmission at the cooperative relay. Particularly, the entire transmission phase and received signal at relay node are divided into two different time durations and three different parts by time allocation (TA) and power splitting (PS), respectively. For the aim of maximizing the sum secrecy rate, adaptive TA factor and PS factor are jointly optimized. We derive the non‐convex optimization function. To solve this highly non‐convex optimization problem, a heuristic approach based on particle swarm optimization (PSO) is proposed. Numerical results verify the superior sum secrecy rate of the proposed scheme. Besides, the impact of system parameters on the output performance is analyzed.
To guarantee secure information transmission within two sources, a full-duplex (FD) relay jamming scheme for two-way energy harvesting (EH) cooperative networks is proposed, in which the relay can achieve simultaneous information reception and jamming transmission. The EH relay node scavenges energy from two source signals, and then, uses the harvested energy for information relaying and jamming transmission by the power splitting (PS) protocol. Considering multiple eavesdroppers, the non-convex optimization for maximizing the smaller bidirectional secrecy rates is formulated by jointly optimizing the power allocation and PS factor. Furthermore, an iterative algorithm based on successive convex approximation and alternate search method is proposed to solve this non-convexity. Simulation results verify the proposed iterative algorithm and show that the proposed jamming scheme can achieve substantial performance gain than other conventional schemes.
This paper studies the cooperative transmission for securing a decode-and-forward (DF) two-hop network where multiple cooperative nodes coexist with a potential eavesdropper. Under the more practical assumption that only the channel distribution information (CDI) of the eavesdropper is known, we propose an opportunistic relaying with artificial jamming secrecy scheme, where a “best” cooperative node is chosen among a collection of N possible candidates to forward the confidential signal and the others send jamming signals to confuse the eavesdroppers. We first investigate the ergodic secrecy rate (ESR) maximization problem by optimizing the power allocation between the confidential signal and jamming signals. In particular, we exploit the limiting distribution technique of extreme order statistics to build an asymptotic closed-form expression of the achievable ESR and the power allocation is optimized to maximize the ESR lower bound. Although the optimization problems are non-convex, we propose a sequential parametric convex approximation (SPCA) algorithm to locate the Karush-Kuhn-Tucker (KKT) solutions. Furthermore, taking the time variance of the legitimate links' CSIs into consideration, we address the impacts of the outdated CSIs to the proposed secrecy scheme, and derive an asymptotic ESR. Finally, we generalize the analysis to the scenario with multiple eavesdroppers, and give the asymptotic analytical results of the achievable ESR. Simulation results confirm our analytical results.
This paper proposes using cooperative relays to improve the ergodic secrecy capacity (ESC) of a multi-hop decode-and-forward (DF) relaying system where communication takes place in the presence of multiple non-colluding eavesdroppers. The proposed scheme is based on a recent approach to generate artificial noise in which transmitter of each hop allocates a portion of its power for generating an intentional interference at the eavesdroppers. Under the assumption that the transmitters can only use limited transmit power, a power allocation strategy has been developed which maximizes the secrecy capacity by optimally distributing the power between the original signal and the artificial noise. Since the optimal solution depends on the channel state information (CSI) of the eavesdroppers, which is difficult to obtain in practice, a sub-optimal solution is also presented in which the CSI of the eavesdroppers is not needed.