Secrecy Precoder Design fork-User MIMO Interference Channels

In this paper, we have studied the secrecy precoder design problem for ak-user multiple-input multiple-output (MIMO) interference channel (IFC), where an external eavesdropper intends to wiretap one of the legitimate wireless links. By adopting the “maxmin” fairness criteria, we define the secure precoding problem as an achievable secrecy-rate maximization problem, which is inherent nonconvex and pretty hard to deal with. To tackle the inherent complexity, we recast the original nonconvex problem into a difference-of-convex (DC) programming problem through a series of equivalent transformations. Based on these endeavors, a coordinated iterative precoding algorithm is designed to solve the achievable secrecy rate maximization problem within the framework of successive convex approximation (SCA) method. The basic idea of the proposed SCA method consists in recasting the DC-programming problem into a series of convexified subproblems, where the nonconvex parts of it are linearized to their first-order Taylor expansion. Moreover, in order to ensure the convergence of the proposed iterative algorithm, a regularization method based on the proximal point idea is also employed. Numerical simulations further show that our algorithm can achieve a satisfactory performance on the premise of ensuring convergence.