Optimal cooperative relaying and jamming for secure communication

This letter considers joint cooperative beamforming and jamming schemes in a cooperative relay network where distributed relay nodes perform cooperative beamforming. The problem of interest is to keep the eavesdropper’s signal to interference and noise ratio (SINR) as low as possible while maintaining the legitimate receiver’s SINR requirement. Applying semidefinite relaxation (SDR) technique, it is shown that a rank-one optimal solution always exists if perfect channel information is available. An optimal relay beamforming scheme has also been proposed for the scenario where only the second-order statistics of the eavesdropper’s channel is available.