In this paper, we study the secrecy communication in two-user MISO interference networks where an external eavesdropper is interested in the messages transmitted by both transmitters. We propose a beamforming design to maximize the achievable secrecy sum rate of the transmitters subject to the individual power constraint at each transmitter. To transform this complex non-convex problem into a convex one, we propose an iterative algorithm based on the constrained concave convex procedure (CCCP) and successive convex approximation (SCA). It is observed that the proposed algorithm converges fast to a stationary point within a few iterations. Furthermore, we also propose a low-complexity null-space beamforming design scheme in which the beamforming vectors have closed-form solutions. Simulation results show the effectiveness of the two proposed schemes in improving the secrecy sum rate performance.
In this paper, we study the secrecy communication in two-user MISO interference networks where an external eavesdropper is interested in the messages transmitted by both transmitters. We propose a beamforming design to maximize the achievable secrecy sum rate of the transmitters subject to the individual power constraint at each transmitter. To transform this complex non-convex problem into a convex one, we propose an iterative algorithm based on the constrained concave convex procedure (CCCP) and successive convex approximation (SCA). It is observed that the proposed algorithm converges fast to a stationary point within a few iterations. Furthermore, we also propose a low-complexity null-space beamforming design scheme in which the beamforming vectors have closed-form solutions. Simulation results show the effectiveness of the two proposed schemes in improving the secrecy sum rate performance.
In this paper, we study the secrecy communication in two-user MISO interference networks where an eavesdropper is only interested in one of the transmitters, i.e., transmitter 1. We propose a generalized beamforming design to maximize the achievable secrecy rate of transmitter 1 while guaranteeing the quality of service (QoS) of the other destination. The non-convex problem can be transformed into a two-stage problem. The inner stage is a semidefinite program (SDP) problem based on the semidefinite relaxation (SDR) and the outer stage is a one dimensional line search problem. It is also shown in the proof that the SDR is always tight and yields a rank-one solution. Furthermore, we also propose a low-complexity null-space beamforming design scheme in which the beamforming vectors can be obtained by solving a second-order cone program (SOCP) problem. Simulation results show the effectiveness of the two proposed schemes in improving the secrecy rate performance.
In this paper, we investigate the secrecy rate maximization problem for a multi user multiple-input single-output (MISO) broadcast interference communication system with simultaneous wireless information and power transfer (SWIPT), in the presence of external eavesdroppers. Assuming that the channel state information is perfectly known at the transmitter, the main aim is to maximize the secrecy rate of the system under signal to interference plus noise ratio (SINR), energy harvesting (EH) and total transmit power constraints. The original secrecy rate maximization problem is non-convex in terms of transmit beamforming matrix and power splitting ratios, usually solved via semi-definite relaxation. In order to circumvent this nonconvexity issue, we propose a concave-convex procedure (CCCP) based iterative algorithm, which provide a local maximum for the secrecy rate maximization. Simulation results are presented to validate the effectiveness of our proposed algorithm. It is demonstrated that our proposed CCCP based iterative algorithm achieves higher secrecy rate and has a lower computational complexity as compared to the conventional SDR technique.
In this letter, we consider secrecy communications over multiple-input single-output K-user interference channel in the presence of multiple eavesdroppers. Each legitimate data link is wiretapped by several eavesdroppers. To keep the eavesdroppers ignorant of the confidential messages, we propose a co-ordinated secure beamforming scheme for maximizing the secrecy sum-rate subject to the individual power constraint of each transmitter. To solve the resultant nonconvex problem, we approximate it into a few semidefinite programs (SDPs) by employing the semidefinite relaxation (SDR) technique and a conservative convex approximation. It is demonstrated experimentally that the proposed algorithm converges within a few iterations. Furthermore, we prove that the SDP problem obtained via SDR always yields a rank-one solution such that the SDR is tight. Simulations show the efficacy of the proposed scheme.
In this paper, we consider max-min fairness for a downlink two-user multi-input single-output (MISO) system with imperfect channel state information available at transmitter (CSIT) taking into account the total power constraint and the physical layer security. Considering the worst-case channel uncertainty for a potential eavesdropper (PE), we study the robust secure beamforming algorithm design which maximizes the minimum achieved worst-case secrecy rate among single-antenna legitimate users. In contrast to existing schemes adopted in the literatures, we propose a rather unorthodox rate splitting (RS) scheme which advocates the dual use of a common message serving both as a desired message and artificial noise (AN) for legitimate users and the PE, respectively. The algorithm design is formulated as a non-convex optimization problem which is generally intractable. As a compromise approach, we apply the successive convex approximation (SCA) method which facilitates the design of a low-complexity suboptimal iterative algorithm. In each iteration, a rank-constrained semi-definite program (SDP) is solved optimally by SDP relaxation (SDR). Simulation results demonstrate that our proposed robust secure beamforming scheme in the MISO-RS secure transmission system outperforms that of the non-robust counterpart. Moreover, our results also unveil that the proposed RS scheme can achieve a superior performance compared to the existing non-orthogonal multiple access (NOMA) schemes and the traditional scheme.
This paper studies the beamforming design problem of a multi-user downlink network, assuming perfect channel state information (CSI) known to the base station (BS). In this scenario, the BS is equipped with multiple antennas, and each user is wiretapped by a specific eavesdropper where each user or eavesdropper is equipped with one antenna. It is supposed that the BS employs transmit beamforming with a given requirement on sum transmitting power. The object is to maximize the sum secrecy rate (SSR) of the network, which leads to a nonconvex complicated structure, and makes he considered beamforming design problem difficult to handle. To solve this problem, a beamforming design scheme is proposed to transform the original problem into a convex approximation problem, by employing semidefinite relaxation (SDR) and first-order approximation technique based on Taylor expansion. Besides, with the advantage of low complexity, a zero-forcing (ZF) based beamforming method is presented in the case that BS is able to nullify he eavesdroppers' rate. Numerical results show that the former strategy achieves better performance than the later one, which is mainly due to the ability of optimizing beamforming direction, and both outperform the traditional signal-to-leakage-and-noise ratio (SLNR) based algorithm.
This paper considers an energy-efficient transmit design in a multiple-input single-output (MISO) wiretap channel. In particular, a transmitter sends one confidential message to a legitimate receiver, which must be kept perfectly secure from multiple external single-antenna eavesdroppers. Assuming statistical eavesdroppers' channel state information (ECSI) at the transmitter, we aim to design the transmit beamformer, such that the outage secrecy energy efficiency (SEE) is maximized, subject to the outage-constrained secrecy rate and transmit power constraints. The resultant problem is intractable to solve even after introducing a semidefinite relaxation (SDR) reformulation. To handle it, an equivalent parametric reformulation, based on the fractional programming and difference-of-concave programming theories, is proposed to recast this problem as a convex problem. By this means, the maximum outage SEE can be found in an iterative fashion. Moreover, we also give an approach to constructing a rank-one covariance matrix from our proposed method, implying the feasibility of transmit beamforming to achieve the obtained SEE performance. Numerical results are presented to show the effectiveness of our proposed method.