Date Added: Apr 2011
In recent years there has been growing interest in study of multi-antenna transmit designs for providing secure communication over the physical layer. This paper considers the scenario of an intended multi-input single-output channel overheard by multiple multi-antenna eavesdroppers. Specifically, the authors address the transmit covariance optimization for Secrecy-Rate Maximization (SRM) of that scenario. The challenge of this problem is that it is a non-convex optimization problem. This paper shows that the SRM problem can actually be solved in a convex and tractable fashion, by recasting the SRM problem as a SemiDefinite Program (SDP). The SRM problem they solve is under the premise of perfect Channel State Information (CSI). This paper also deals with the imperfect CSI case.