Co-Ordinated Secure Beamforming in $K$ -User Interference Channel With Multiple Eavesdroppers

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.