In this paper, we address the problem of secrecy wireless information and power transfer (SWIPT) over interference channels, where an external eavesdropper is also interested in the transmitted message. Under a practical assumption that only imperfect eavesdropper channel state information (CSI) is available, our objective is to minimize the total transmit power while satisfying the constraints on the minimum amounts of individual harvested energy, the worst-case achievable secrecy rate of the wiretapped node, and the minimum signal-to-interference-plus-noise ratio (SINR) at the wiretap-free node. An optimal robust secure beamforming and power splitting scheme is obtained via the aid of a one-dimensional search. Moreover, in order to reduce the computational complexity, we also propose a suboptimal scheme based on zero-forcing beamforming (ZFB). Finally, simulation results validate the effectiveness of the proposed schemes.
In this paper, we address the problem of secrecy wireless information and power transfer (SWIPT) over interference channels, where an external eavesdropper is also interested in the transmitted message. Under a practical assumption that only imperfect eavesdropper channel state information (CSI) is available, our objective is to minimize the total transmit power while satisfying the constraints on the minimum amounts of individual harvested energy, the worst-case achievable secrecy rate of the wiretapped node, and the minimum signal-to-interference-plus-noise ratio (SINR) at the wiretap-free node. An optimal robust secure beamforming and power splitting scheme is obtained via the aid of a one-dimensional search. Moreover, in order to reduce the computational complexity, we also propose a suboptimal scheme based on zero-forcing beamforming (ZFB). Finally, simulation results validate the effectiveness of the proposed schemes.
This paper studies the secure beamforming design for simultaneous wireless information and power transfer in a multiple-input single-output broadcast channel with confidential messages and external eavesdroppers, where each receiver adopts the power splitting (PS) scheme to decode information and harvest energy concurrently, and it is also seen as a potential eavesdropper for messages not intended for it. Our objective is to minimize the total transmit power while guaranteeing the individual secrecy rate and energy harvesting constraints at each receiver by jointly optimizing transmit beamforming vectors, artificial noise covariance, and receive PS ratios. Both scenarios of perfect and imperfect channel state information (CSI) at the transmitter are considered. For the perfect CSI case, we propose a two-stage optimization approach to solve the original non-convex problem global optimality, and also provide a low-complexity suboptimal solution based on the particle swarm optimization algorithm. Furthermore, we also extend the above result to the colluding eavesdroppers scenario. For the imperfect CSI case, we propose a worst-case-based robust formulation, where the CSI errors are norm-bounded. With the aid of S-Procedure, we derive the equivalent forms for constraints and then transform the non-convex robust design into a convex optimization problem. Simulation results are finally presented to demonstrate the performance of our proposed schemes.
In this paper, we give a unified performance optimization for secrecy wireless information and power transfer over interference channels, where an external eavesdropper is also interested in the confidential message. We propose to perform cooperative energy beamforming between two sources to confuse the eavesdropper while satisfying the requirements on the minimum amounts of individual harvested energy, and the minimum signal-to-interference-plus-noise ratio at the wiretap-free node, even under an adverse condition that there exist channel uncertainties at the transmitters. Considering the maximization of secrecy rate subject to a power constraint and the minimization of power consumption with a minimum secrecy rate requirement are two commonly used design objectives for secure communications, we give a unified performance optimization from the both perspectives. Especially, since there exists channel uncertainty, we propose to optimize the worst performance, so as to satisfy the performance requirements under all channel conditions. To achieve a balance between system performance and implementation complexity, we present a robust cooperative beamforming and power splitting scheme for each secrecy problem while confining the information signal in the null space of the interference channel. Finally, simulation results validate the effectiveness of the proposed schemes.
In this paper, we investigate multiple-input single-output (MISO) simultaneous wireless information and power transfer (SWIPT) broadcast channels with confidential messages (BCC) scenario, in which a multiple-antenna transmitter simultaneously transmits confidential messages and power to multiple single-antenna receivers. Considering the imperfect channel state information (CSI), we study the joint optimization of transmit beamforming vectors, covariance of artificial noise, and power splitting ratios so as to minimize the total transmit power while satisfying the worst-case conservative secrecy rate and energy harvesting constraints. The original optimization is non-convex and intractable in general. To handle this challenge, in this paper, we first derive the exact upper or lower bounds of the constraints in original optimization problem by using the Lagrangian approach, and then convert the corresponding non-convex problem into a convex one with the aid of the rank relaxation technique. Finally, we provide simulation results to illustrate the robustness of the proposed design.
This paper addresses robust designs of secure simultaneous wireless information and power transfer for multiple-input single-output (MISO) multiuser systems. By using a bounded uncertainty model for the channel state information (CSI) from transmitters to legitimate receivers and under the assumption of only available statistic knowledge of the CSI to eavesdroppers, we consider the robust designs with both worst-case and chance-constrained optimizations. To jointly optimize transmit beamforming vectors and power splitting factors, we formulate three problems aiming at minimizing the system power, maximizing the sum secrecy rate, and maximizing the minimal secrecy rate, respectively, subject to both energy harvesting and secrecy outage constraints. These problems are intractable in their original forms due to the CSI models and their non-convexity. To reach computationally efficient solutions, we first rewrite the original problems by semi-definite relaxation, then transform the CSI uncertainty related constraints by S-procedure, and finally approximate the non-convex constraints by the first-order Taylor expansion. By the reformulations, we present iterative successive convex approximation algorithm for approaching the optimized solutions. Simulation results under various setups of system parameters are provided to examine the system performance and validate the effectiveness of the proposed schemes.
This paper studies a simultaneous wireless information and power transfer (SWIPT) system in which the transmitter not only sends data and energy to many types of wireless users, such as multiple information decoding users, multiple hybrid power-splitting users (i.e., users with a power-splitting structure to receive both information and energy), and multiple energy harvesting users, but also prevents information from being intercepted by a passive eavesdropper. The transmitter is equipped with multiple antennas, whereas all users and the eavesdropper are assumed to be equipped with a single antenna. Since the transmitter does not have any channel state information (CSI) about the eavesdropper, artificial noise (AN) power is maximized to mask information as well as to interfere with the eavesdropper as much as possible. The non-convex optimization problem is formulated to minimize the transmit power satisfying all signal-to-interference-plus-noise (SINR) and harvested energy requirements for all users so that the remaining power for generating AN is maximized. With perfect CSI, a semidefinite relaxation (SDR) technique is applied, and the optimal solution is proven to be tight. With imperfect CSI, SDR and a Gaussian randomization algorithm are proposed to find the suboptimal solution. Finally, numerical performance with respect to the maximum SINR at the eavesdropper is determined by a Monte-Carlo simulation to compare the proposed AN scenario with a no-AN scenario, as well as to compare perfect CSI with imperfect CSI.
In this paper, we consider a multiuser multiple-input multiple-output (MIMO) downlink communication system with simultaneous wireless information and power transfer (SWIPT). In particular, we focus on a realistic and efficient multi-receiver multi-eavesdropper MIMO SWIPT system, in which the channel state information (CSI) of each legitimate receiver and energy receiver (i.e., potential eavesdropper) is partially known to the transmitter. Based on this, we propose a robust artificial noise (AN)-aided secure transmission scheme for the system, where the channel uncertainties are modeled by the worst-case model. In the proposed scheme, we aim to maximize the worst-case achievable secrecy rate under the transmit power constraint and the energy harvesting (EH) constraint, by jointly optimizing the transmit precoding matrix and the AN covariance matrix. We utilize the S-Procedure and Taylor series approximation to transform the non-convex problem. Then, we apply the interior point method to tackle the transformed convex problem, obtaining the approximate optimal matrices and the corresponding maximum worst-case secrecy rate. Simulation results show that our proposed scheme achieves significant performance improvements in terms of convergence and the worst-case achievable secrecy rate.