This paper investigates secure communications of energy harvesting untrusted relay networks, where the destination assists jamming signal to prevent the untrusted relay from eavesdropping and to improve the forwarding ability of the energy constrained relay. Firstly, the source and the destination transmit the signals to the relay with maximal ratio transmission (MRT) technique or transmit antenna selection (TAS) technique. Then, the destination utilizes maximal ratio combining (MRC) technique or receive antenna selection (RAS) technique to receive the forwarded information. Therefore, four transmission and reception schemes are considered. For each scheme, the closed-form expressions of the secrecy outage probability (SOP) and the connection outage probability (COP) are derived. Besides, the effective secrecy throughput (EST) metric is analyzed to achieve a good tradeoff between security and reliability. In addition, the asymptotic performance of EST is also considered at the high signal-to-noise ratio (SNR). Finally, simulation results illustrate that: (1) the EST of the system with MRT and MRC scheme are superior to other schemes, however, in the high SNR regime, the EST of the system with MRT scheme is inferior to TAS; and (2) for the source node, there exists an optimal number of antennas to maximize the EST of the proposed schemes.
This paper investigates secure communications of energy harvesting untrusted relay networks, where the destination assists jamming signal to prevent the untrusted relay from eavesdropping and to improve the forwarding ability of the energy constrained relay. Firstly, the source and the destination transmit the signals to the relay with maximal ratio transmission (MRT) technique or transmit antenna selection (TAS) technique. Then, the destination utilizes maximal ratio combining (MRC) technique or receive antenna selection (RAS) technique to receive the forwarded information. Therefore, four transmission and reception schemes are considered. For each scheme, the closed-form expressions of the secrecy outage probability (SOP) and the connection outage probability (COP) are derived. Besides, the effective secrecy throughput (EST) metric is analyzed to achieve a good tradeoff between security and reliability. In addition, the asymptotic performance of EST is also considered at the high signal-to-noise ratio (SNR). Finally, simulation results illustrate that: (1) the EST of the system with MRT and MRC scheme are superior to other schemes, however, in the high SNR regime, the EST of the system with MRT scheme is inferior to TAS; and (2) for the source node, there exists an optimal number of antennas to maximize the EST of the proposed schemes.
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.
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.
In this work, we focus on the issue of secure communication in energy harvesting untrusted relay networks taking into account the impact of hardware impairments, where an energy‐constrained relay, powered by received radio frequency signals, attempts to decode sensitive data from the source without authorization. To achieve secure communication, we employ destination‐assisted jamming to prevent the untrusted relay from decoding sensitive data while serving as a useful energy source. We derive the interception probability (IP), connection outage probability (COP), and effective secrecy throughput (EST) in closed form for time switching relaying (TSR) strategy. Subsequently, we conduct an asymptotic analysis in the high signal‐to‐noise ratio (SNR) regime to provide practical insights into how various system parameters affect security, reliability, and efficiency, including time switching factor and the level of hardware impairments. Our findings demonstrate that the presence of hardware impairments improves security performance but compromises reliability performance, which does more harm than good.
In this work, we investigate the secrecy performance in multi-antenna untrusted relay networks, where destination-aided jamming is incorporated to help reduce the amount of confidential information leaked to an untrusted relay. We conduct a robust secrecy performance analysis for the worst-case scenario, where the antenna selection technique is performed at the untrusted relay for data reception and retransmission, and the selected antenna is the one with the highest probability of interrupting the confidential information. In addition, maximal ratio transmission is used at the source and destination for sending information and jamming signals. Under this transmission scheme, we derive the novel exact and asymptotic closed-form expressions for the secrecy outage probability (SOP) to evaluate the secrecy performance with arbitrary number of antennas. Numerical and simulation results indicate that there exists an optimal number of transmit antennas at the source to achieve the tradeoff between reliability and security.
This article studies a secure communication of a simultaneous wireless information and power transfer system in which an energy-constrained untrusted relay, which harvests energy from the wireless signals, helps the communication between the source and destination and is able to decode the source’s confidential signal. Additionally, the source’s confidential signal is also overheard by a passive eavesdropper. To create positive secrecy capacity, a destination-assisted jamming signal that is completely cancelled at the destination is adopted. Moreover, the jamming signal is also exploited as an additional energy source. To evaluate the secrecy performance, analytical expressions for the secrecy outage probability (SOP) and the average secrecy capacity are derived. Moreover, a high-power approximation for the SOP is presented. The accuracy of the analytical results is verified by Monte Carlo simulations. Numerical results provide valuable insights into the effect of various system parameters, such as the energy-harvesting efficiency, secrecy rate threshold, power-splitting ratio, transmit powers, and locations of the relay and eavesdropper, on the secrecy performance.
This paper proposes a secure wireless communication system that integrates Physical Layer Security (PLS) with Energy Harvesting (EH) to improve both data confidentiality and network sustainability. The system model consists of a source node S, powered by energy harvested from spatially distributed power stations, a multi-antenna destination node D, and an eavesdropper node E located within the communication range. A time-switching protocol enables the source node S to alternate between energy harvesting and secure data transmission. To enhance signal quality and system security, the destination node D employs Selection Combining (SC) and Maximal Ratio Combining (MRC) techniques to mitigate fading effects and eavesdropping risks. Analytical expressions for the Signal-to-Noise Ratios (SNRs) at both the destination D and the eavesdropper E are derived, along with the Probability Density Function (PDF) and Cumulative Distribution Function (CDF) of these SNRs under block Rayleigh fading conditions. Furthermore, an exact analytical formulation for Secrecy Outage Probability (SOP) is presented, quantifying the probability of information leakage under various system configurations. The proposed model is validated through extensive Monte Carlo simulations, which confirm the accuracy of the mathematical analysis of SOP. Based on simulation results, the impact of key system parameters—such as energy harvesting efficiency η, time-switching protocol parameter α, the number of antennas M at the destination node, and the number of beacon nodes N—on SOP is analyzed. The results provide valuable insights for optimizing secure and energy-efficient communication in wireless networks.