Simultaneous wireless information and power transfer (SWIPT) has recently drawn significant interests for its dual use of radio signals to provide wireless data and energy access at the same time. However, a challenging secrecy communication problem arises in the SWIPT system since the messages sent to information receivers (IRs) may be eavesdropped by energy receivers (ERs), which are presumed to receive energy from the same signals broadcast by the transmitter. To tackle this problem, we propose in this paper an artificial noise (AN) aided transmission scheme to facilitate the secrecy information transmission to IRs and yet meet the energy harvesting requirement for ERs, under the assumption that the AN can be cancelled at IRs but not at ERs. Specifically, the proposed scheme splits the power at the transmitter into two parts, to send the confidential message to the IR and an AN to interfere with the ER against eavesdropping, respectively. Under a simplified three-node wiretap channel setup, the transmit power allocations and power splitting ratios over fading channels are jointly optimized to maximize the average secrecy information rate for the IR subject to a combination of average and peak power constraints at the transmitter as well as an average energy harvesting constraint at the ER. The formulated problem is shown to be non-convex, for which we propose an efficient algorithm by iteratively optimizing the transmit power allocations and power splitting ratios over fading channels. Finally, the performance of the proposed scheme is evaluated by simulations and compared against other heuristic schemes in terms of achievable (secrecy) rate-energy trade-off.
Simultaneous wireless information and power transfer (SWIPT) has recently drawn significant interests for its dual use of radio signals to provide wireless data and energy access at the same time. However, a challenging secrecy communication problem arises in the SWIPT system since the messages sent to information receivers (IRs) may be eavesdropped by energy receivers (ERs), which are presumed to receive energy from the same signals broadcast by the transmitter. To tackle this problem, we propose in this paper an artificial noise (AN) aided transmission scheme to facilitate the secrecy information transmission to IRs and yet meet the energy harvesting requirement for ERs, under the assumption that the AN can be cancelled at IRs but not at ERs. Specifically, the proposed scheme splits the power at the transmitter into two parts, to send the confidential message to the IR and an AN to interfere with the ER against eavesdropping, respectively. Under a simplified three-node wiretap channel setup, the transmit power allocations and power splitting ratios over fading channels are jointly optimized to maximize the average secrecy information rate for the IR subject to a combination of average and peak power constraints at the transmitter as well as an average energy harvesting constraint at the ER. The formulated problem is shown to be non-convex, for which we propose an efficient algorithm by iteratively optimizing the transmit power allocations and power splitting ratios over fading channels. Finally, the performance of the proposed scheme is evaluated by simulations and compared against other heuristic schemes in terms of achievable (secrecy) rate-energy trade-off.
Simultaneous wireless information and power transfer (SWIPT) has recently drawn significant interest for its dual use of radio signals to provide wireless data and energy access at the same time. However, a challenging secrecy communication issue arises as the messages sent to the information receivers (IRs) may be eavesdropped upon by energy receivers (ERs), which are presumed to harvest energy only from received signals. To tackle this problem, we propose in this paper an artificial-noise (AN)-aided transmission scheme to facilitate the secrecy information transmission to IRs and, yet, meet the energy harvesting requirement for ERs, under the assumption that the AN can be canceled at IRs but not at ERs. Specifically, the proposed scheme splits the transmit power into two parts: to send the confidential message to the IR and an AN to interfere with the ER, respectively. Under a simplified three-node wiretap channel setup, the transmit power allocations and power splitting ratios over fading channels are jointly optimized to minimize the outage probability for delay-limited secrecy information transmission or to maximize the average rate for no-delay-limited secrecy information transmission, subject to a combination of average and peak power constraints (APC and PPC) at the transmitter (Tx) and an average energy harvesting constraint at the ER. Both the secrecy outage probability minimization and average rate maximization problems are shown to be nonconvex, and for each, we propose the optimal solution based on the dual decomposition and the suboptimal solution based on the alternating optimization. Furthermore, two benchmark schemes are introduced for comparison where the AN is not used at the Tx and where the AN is used but cannot be canceled by the IR, respectively. Finally, the performances of proposed schemes are evaluated by simulations in terms of various tradeoffs for wireless (secrecy) information versus energy transmissions.
In this paper, we study simultaneous wireless information and power transfer (SWIPT) in orthogonal frequency division multiple access (OFDMA) systems with the coexistence of information receivers (IRs) and energy receivers (ERs). The IRs are served with best-effort secrecy data and the ERs harvest energy with minimum required harvested power. To enhance the physical layer security for IRs and yet satisfy energy harvesting requirements for ERs, we propose a new frequency-domain artificial noise (AN) aided transmission strategy. With the new strategy, we study the optimal resource allocation for the weighted sum secrecy rate maximization for IRs by power and subcarrier allocation at the transmitter. The studied problem is shown to be a mixed integer programming problem and thus nonconvex, while we propose an efficient algorithm for solving it based on the Lagrange duality method. To further reduce the computational complexity, we also propose a suboptimal algorithm of lower complexity. The simulation results illustrate the effectiveness of proposed algorithms as compared against other heuristic schemes.
This paper studies the secure transmission issue for simultaneous wireless information and power transfer (SWIPT) in a multiuser system with multiple eavesdroppers, where the base station transmitter broadcasts confidential message to legitimate multiple single-antenna information receivers (IRs) and multiple single-antenna energy-harvesting receivers (ERs). Our objective is to optimize the information bearing beam and artificial energy-carrying noise beam in order to maximize the secrecy rate of the IRs subject to individual harvested energy constraints of the ERs for the case where the ERs can form eavesdropping party to carry out joint decoding in an attempt to illicitly decode the secret message intended for the IRs. The initial non-convex problem is converted to convex problem through semi-definite programming (SDP) relaxation for both perfect CSI and imperfect CSI. Numerical simulations are presented to demonstrate the performance.
In this paper, we investigate the secure transmission in multiple-input multiple-output (MIMO) communication systems with simultaneous wireless information and power transfer (SWIPT), where the energy receivers (ERs) may eavesdrop the confidential information send to the desired receiver (DR). By taking into account both artificial noise (AN) and power splitting (PS), we aim to maximize the secrecy rate at the DR by jointly designing the precoding matrix, AN covariance matrix and PS ratio at the desired receiver, under the transmit power constraint and the energy harvesting (EH) constraints at all the receivers. To solve the formulated non-convex problem, we propose an alternating optimization (AO) algorithm through a judicious reformulation, wherein the problem is handled by solving a series of convex problems in an alternating method. Finally, numerical results are provided to validate our proposed algorithm.
The simultaneous wireless information and power transfer (SWIPT) technique is regarded as a promising approach to enhance performance of wireless networks with limited energy supply. However, due to the broadcast nature of wireless radio, the energy receiver may act as a potential eavesdropper to eavesdrop the information sent to the information receiver. To address this issue, in this paper, we propose an optimization framework of the target secrecy rate and the power allocation ratio based on the secrecy outage probability and the effective secrecy throughput in the SWIPT system over fading wiretap channel. Moreover, we derive the closed-form expression of the secrecy outage probability and the effective secrecy throughput for two secrecy transmission modes. Furthermore, we formulate the effective secrecy throughput maximization problem under the reliability constraint in the on-off and adaptive transmission modes and provide the closed-form optimal solutions of the power allocation ratio and the target secrecy rate. Finally, we provide numerical results that give an insight into the effect of various system parameters on the secrecy outage probability and the effective secrecy throughput, such as the target secrecy rate, the power allocation ratio, and average gains of the main channel and the eavesdropper channel.
Owing to the tendency of RF-powered wireless devices to be located closer to the RF sources in SWIPT systems, the secrecy performance of RF transmissions needs to be carefully studied. In this paper, we study the secrecy performance of a wireless network that is simultaneously transmitting information and power to information receivers (IRs) and energy receivers (ERs), respectively. Considering the ERs as potential eavesdroppers, we provide a generalized model that captures three popular secrecy enhancing techniques: (i) adding artificial noise (AN) to the transmitted signal, (ii) surrounding the information transmitters (ITs) with secrecy guard zones, and (iii) using directional beamforming towards the intended IRs. Assuming an interference-limited system, we use the proposed generalized model to derive the successful connection and the secrecy outage probabilities of the IR (Pconand Pout, respectively) and the energy coverage probability (Penergy) of the ER for each of the three techniques. We then study the influence of the guard zone radius, the AN power splitting ratio, and the beamwidth on these performance metrics. We focus on two parameter selection criteria: (i) minimizing Poutfor given constraints on Pconand Penergy, and (ii) maximizing Pconfor given constraints on Pout and Penergy. At lower densities of ERs, the results demonstrate the optimality of the GZ technique for the first selection criterion and the BF technique for the second selection criterion. At higher densities of ERs, however, the AN technique is shown to be optimal for both the selection criteria.