Robust Beamforming Techniques for MISO Secrecy Communication with a Cooperative Jammer

This paper investigates robust beamforming techniques for a multiple-input-single-output (MISO) secrecy transmission with a cooperative jammer by incorporating two different types of channel uncertainties. We solve the worst-case signal-to-interference-plus-noise ratio (SINR) maximization of the legitimate user with the worst-case SINR constraint of the eavesdropper and the transmit power constraint. The original problems are not convex in terms of transmit covariance matrices, and cannot be solved directly. Thus, we present two approaches to convert these problems into semidefinite programmings (SDPs) by exploiting S-Procedure and deriving the corresponding Lagrangian dual problem. Numerical results are provided to validate the performance of the proposed robust schemes.