Precoding Optimization for Secure Target User in Multi-Antenna Broadcast Channel

In this paper, we focus on the physical-layer security of a multiuser cellular downlink system. A multi-antenna base station (BS) communicates with several legitimate users, where a target user is overheard by an eavesdropper in the downlink transmission. We aim at designing linear precoders for the BS to maximize the secrecy rate of target user under the condition that a certain Quality-of- Service (QoS) is guaranteed for the other legitimate users. To solve the non-convex optimization problem, we propose an iterative algorithm to transform the original problem into a sequence of approximate convex problems, which can be solved using interior point method. Simulation results reveal that compared with two other methods dealing with the similar optimization problem in previous works, our proposed method can achieve a higher secrecy rate.