PHY layer security in multiple antenna systems by joint transmitter/receiver artificial noise generation through semidefinite programming

We address physical layer security in multiple-input-multiple-output (MIMO) communications. We introduce a worst-case robust transmission strategy to broadcast artificial noise jointly from the transmitter and/or the receiver under a mismatched version of the channel state information (CSI) between all the communication parties. We determine the transmission covariance matrices that maximise the worst-case secrecy rate in a global power constrained system considering two cases regarding the knowledge about the eavesdropping channel: i) partial instantaneous, and ii) second-order statistics. The resulting problems turn out to be nonconvex and so we approximate them to tractable semidefinite programs (SDP). The proposed technique introduces flexibility to generate the artificial noise from either authorised source depending on the particular transmission conditions enhancing the security performance.