In this study, the authors propose a generalisedswitching protocol (GSP) for increasing the flexibility of energy harvesting (EH) protocol and enhancing the security of amplify‐and‐forward (AF) multi‐antenna relaying system. The proposed GSP‐based relaying [generalised switching relaying (GSR)] system is established with target node assisted interference and EH technologies. In phase I, while the source transmits certain signal to the relay, the destination transmits an artificial noise to interfere the passive eavesdropper. In this phase, the relay harvests energy from the two nodes. In phase II, the relay node processes the two different received signals, which are from the source and destination, then AF them by utilising the harvested energy. The authors also derive a new analytical formula for the proposed protocol on ergodic secrecy capacity. The effect of the number of relay antennas N , the source transmitted power , the destination transmitted power and EH efficiency factors and on ergodic secrecy capacity are investigated. The simulation results show that as N , , , and increase, the ergodic secrecy capacity of GSR system increases accordingly. Moreover, the GSR protocol can provide higher ergodic secrecy capacity than both time switching relaying and powersplitting relaying protocols.
In this study, the authors propose a generalisedswitching protocol (GSP) for increasing the flexibility of energy harvesting (EH) protocol and enhancing the security of amplify‐and‐forward (AF) multi‐antenna relaying system. The proposed GSP‐based relaying [generalised switching relaying (GSR)] system is established with target node assisted interference and EH technologies. In phase I, while the source transmits certain signal to the relay, the destination transmits an artificial noise to interfere the passive eavesdropper. In this phase, the relay harvests energy from the two nodes. In phase II, the relay node processes the two different received signals, which are from the source and destination, then AF them by utilising the harvested energy. The authors also derive a new analytical formula for the proposed protocol on ergodic secrecy capacity. The effect of the number of relay antennas N , the source transmitted power , the destination transmitted power and EH efficiency factors and on ergodic secrecy capacity are investigated. The simulation results show that as N , , , and increase, the ergodic secrecy capacity of GSR system increases accordingly. Moreover, the GSR protocol can provide higher ergodic secrecy capacity than both time switching relaying and powersplitting relaying protocols.
In this paper, we proposed a generalized energy harvesting (GEH) protocol and utilized a non-linear energy harvesting (EH) model for AF Multi-Antenna Relaying Systems. In particular, the GEH protocol is a optimal EH protocol based on time switching relaying (TSR) and power splitting relaying (PSR) protocols. The whole communication process contains two phases. In phase I, the source transmits certain signal to the relay, meanwhile the destination transmits an artificial noise (AN) to interfere with the passive eavesdropper. The relay harvests energy from the two nodes. In phase II, the relay node processes the two different received signals, which are transmitted from the source and destination. Then the relay amplify-and-forward them by utilizing the harvested energy. To accurately reflect the non-linear nature of the practical EH circuit of GEH-based systems, we apply a special kind of quasi-concave function named logistic (sigmoidal) function to model the input-output characteristic. We also derive a new analytical formula for proposed generalized non-linear energy harvesting protocol on ergodic secrecy capacity. The effect of the number of relay antennas N, the source transmitted power Pthe destination transmitted power Pd on ergodic secrecy capacity are investigated. The simulation results show that as N, Ps, Pd increase, the ergodic secrecy capacity of GEH system increases accordingly. Moreover, the GEH protocol can provide higher non-linear ergodic secrecy capacity than time switching relaying (TSR) protocol and almost perform as better as power splitting relaying (PSR) protocol.
In this paper, we analyze the secrecy capacity of a half-duplex energy harvesting (EH)-based multi-antenna amplify-and-forward relay network in the presence of a passive eavesdropper. During the first phase, while the source is in the transmission mode, the legitimate destination transmits an auxiliary artificial noise (AN) signal which has two distinct purposes: 1) to transfer power to the relay and 2) to improve system security. Since the AN is known at the legitimate destination, it is easily cancelled at the intended destination, which is not the case at the eavesdropper. In this respect, we derive new exact analytical expressions for the ergodic secrecy capacity for various well-known EH relaying protocols, namely, time switching relaying (TSR), power splitting relaying (PSR), and ideal relaying receiver (IRR). Monte Carlo simulations are also provided throughout our investigations to validate the analysis. The impacts of some important system parameters, such as EH time, power splitting ratio, relay location, AN power, EH efficiency, and the number of relay antennas, on the system performance are investigated. The results reveal that the PSR protocol generally outperforms the TSR approach in terms of the secrecy capacity.
This paper analyzes the ergodic secrecy capacity of an energy-constrained multiple-antennas amplify-and-forward (AF) relaying system in the presence of a passive eavesdropper. In the first phase, the source broadcasts information signal, while the destination sends an artificial jamming signal. The jamming signal has two main purposes: 1) enhancing the system security; 2) increasing the energy harvesting (EH) at the relay node. In the second phase, the relay uses the harvested energy to amplify and forward the received signal to the destination. For this system model, explicit mathematical expressions for the ergodic secrecy capacity are derived for three different common EH-relaying protocols, namely, power splitting relaying (PSR), antenna selection and power splitting (ASPS) receiver, and ideal relaying receiver (IRR). Monte-Carlo simulations are included to validate the analysis and the effect of different parameters on the system security are investigated. The results show that, the ASPS receiver outperforms PSR in terms of secrecy capacity.
In this study, the authors propose a cooperative transmission scheme with energy‐harvesting (EH) relays under wiretapping of an eavesdropper. In this scheme, the relays harvest energy from radio‐frequency (RF) signals of a source through power‐splitting receivers, and process arrived signals by amplify‐and‐forward (EH‐AF protocol) and decode‐and‐forward (EH‐DF protocol) technologies. In the proposed protocols, a best relay is selected at the destination so that the end‐to‐end achievable secrecy rates are maximal. Exact and asymptotic secrecy outage probability expressions are used to evaluate the EH‐AF and EH‐DF protocols, respectively, and are confirmed by Monte Carlo simulations. The simulation results show that (i) the EH‐DF protocol outperforms the EH‐AF protocol, and both proposed protocols are improved when the number of cooperative relays and the distances of the relay–eavesdropper links increase and the relays move toward the destination, (ii) the secrecy performance of the EH‐AF and EH‐DF protocols is the best at optimal power‐splitting ratios, which are obtained by the golden section search method, (iii) the energy conversion efficiency and the noise at RF‐to‐baseband conversion units seriously affect the proposed protocols, and finally, (iv) the theoretical analysis results fit those of the Monte Carlo simulations.
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.
Summary In this paper, we investigate the problem of secure communication for a scenario, which consists of one pair of source‐destination nodes and one untrusted relay. The source communicates with the destination via the help of energy harvesting–aware untrusted relay, which acts as the helper to forward the source information to the destination; however, the relay also acts as the unintended user to eavesdrop the source information. To keep the source information confidential from untrusted relay, the destination‐assisted jamming technique is deployed. We evaluate the impact of energy harvesting protocols on such a secure communication scenario through the proposed energy transfer protocols, namely, source‐based energy harvesting protocol and maximum energy harvesting protocol. To evaluate the secrecy performance of these proposed schemes, we derive analytical expressions for two important performance metrics including intercept probability and strictly positive secrecy capacity. The numerical analysis reveals the different trade‐off between secure performance and relevant system parameters (i.e., power splitting ratio, time switching ratio, energy conversion efficiency, transmit signal‐to‐noise ratio, and relay location). Simulation results are also provided to demonstrate the accuracy of the developed analytical expression.