The secrecy performance of a wireless‐powered relaying system is investigated in the presence of imperfect channel state information. To improve the system secrecy performance, the destination splits a part of power to transmit the cooperative interference signal while the source transmits confidential information to the relay. The relay is assumed to be equipped with a non‐linear energy harvester and to harvest energy from the source and destination for information processing. A joint power splitting and time allocation scheme is studied to maximise the system secrecy rate. The joint optimisation problem is dealt with by the interior‐point method. For the sake of comparison, the equal time allocation scheme and the equal power splitting scheme are also investigated. The numerical results verify that the proposed scheme could achieve higher secrecy rate.
The secrecy performance of a wireless‐powered relaying system is investigated in the presence of imperfect channel state information. To improve the system secrecy performance, the destination splits a part of power to transmit the cooperative interference signal while the source transmits confidential information to the relay. The relay is assumed to be equipped with a non‐linear energy harvester and to harvest energy from the source and destination for information processing. A joint power splitting and time allocation scheme is studied to maximise the system secrecy rate. The joint optimisation problem is dealt with by the interior‐point method. For the sake of comparison, the equal time allocation scheme and the equal power splitting scheme are also investigated. The numerical results verify that the proposed scheme could achieve higher secrecy rate.
In this paper, the secure information transmission of an energy harvesting (EH) cooperative network is considered, in which multiple eavesdroppers can overhear the forwarded relay signal. To prevent multiple eavesdroppers from decoding confidential signals, the destination transmits the jamming signal while the source transmits the confidential signal to the relay. Simultaneously, the relay can harvest more energy from source signals and destination jamming by the power splitting (PS) protocol, which is depicted as a non-linear EH process. Considering the imperfect self-interference cancellation (SIC) at the destination, secrecy rate maximization optimization is formulated to optimize the transmission power of source and destination. However, the formulated optimization is non-convex. To solve this problem, an iterative algorithm is proposed based on the difference of convex functions (DC) programming, which can transform non-convex optimization problems into successive approximate convex problems. Simulation results show that the proposed algorithm has a quick convergence rate, and the proposed scheme leads to a higher achievable secrecy rate.
Abstract The secrecy rate of two‐way untrusted relay networks with imperfect channel state information based on SWIPT is investigated when multiple relays harvest energy from two sources. Despite assisting in information forwarding, the relays are considered untrusted in that they might attempt to eavesdrop on confidential information. To interfere with eavesdropping by untrusted relays, sources‐based friendly cooperative jamming is introduced. A joint power allocation and time switching strategy has been studied to maximize the sum secrecy rate of the system under total block transmission duration and power constraints. The genetic algorithm (GA) is introduced to optimize the proposed joint power allocation and time switching (JPTs) scheme. In addition, two suboptimal schemes are proposed: the power allocation and time switching scheme for individual power constraints and the power allocation scheme for equal time allocation. Simulation results demonstrate that the proposed joint power allocation and time switching strategy performs better in contributing to the total secrecy rate of the system.
The broadcast nature of the wireless medium allows unintended users to eavesdrop on confidential information transmission. In this regard, we investigate the problem of secure communication between a source and a destination via a wireless energy harvesting untrusted node that acts as a helper to relay the information; however, the source and destination nodes wish to keep the information confidential from the relay node. To realize the positive secrecy rate, we use destination-assisted jamming. Being an energy-starved node, the untrusted relay harvests energy from the received radio-frequency (RF) signals, which include the source's information signal and the destination's jamming signal. Thus, we utilize the jamming signal efficiently by leveraging it as a useful energy source. At the relay, to enable energy harvesting and information processing, we adopt power splitting (PS) and time switching (TS) policies. To evaluate the secrecy performance of this proposed scenario, we derive analytical expressions for two important metrics, viz., the secrecy outage probability and the ergodic secrecy rate. The numerical analysis reveals design insights into the effects of different system parameters such as PS ratio, energy harvesting time, target secrecy rate, transmit signal-to-noise ratio (SNR), relay location, and energy conversion efficiency factor, on secrecy performance. Specifically, the PS policy achieves better optimal secrecy outage probability and optimal ergodic secrecy rate than that of the TS policy at higher target secrecy rate and transmit SNR, respectively.
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.
In this paper, we investigate the achievable secrecy rate in a relay channel where the source and the destination wish to keep the information confidential from an untrusted relay (potential eavesdropper). The relay has no energy supply, and harvests its required energy for relaying from its received signals. For radio-frequency (RF) Energy Harvesting (EH) at the relay, we adopt power splitting (PS) approach. We study the problem of achieving positive secrecy rates between the transmitter and the receiver while making use of an untrusted relay. Energy limitation at the relay makes the problem more interesting. Because, the relay must choose either to eavesdrop the signal to be able to decode or to harvest energy (from the information signal) to be able to forward the message. Our scheme to guarantee the secrecy uses cooperative jamming by either the destination or an extra jammer node. We derive the achievable secrecy rates for the compress-and-forward (CF) and amplify-and-forward (AF) relays for two different scenarios. First, we assume the destination and the jammer are two separate nodes. Then, we consider destination-assisted jamming. In addition, we let the relay to use both the sources and the jammers transmitted signals to harvest energy. Our numerical results show that our proposed schemes guarantee a positive secrecy rate by properly locating the jammer and allocating enough jamming power. However, for a given power budget (i.e., fixed total transmission and jamming power) there is an optimum amount for the jamming power.
In this study, the problem of energy‐efficient power allocation (EEPA) for secrecy wireless information and power transfer in a massive multiple‐input multiple‐output relay aided secure communication system is well addressed. The relay forwards the signal sent from a source to a legitimate destination with the harvested energy based on a decode‐and‐forward relaying protocol, while a passive eavesdropper intends to intercept the message. The authors first derive a closed‐form expression for the secrecy energy efficiency of the considered system under practical conditions, i.e. no instantaneous eavesdropper channel state information (CSI) and only imperfect legitimate CSI. Then, they propose an EEPA scheme for maximising the secrecy energy efficiency. Finally, simulation results validate the effectiveness of the proposed scheme.