Secure Beamforming and Ergodic Secrecy Rate Analysis for Amplify-and-Forward Relay Networks with Wireless Powered Jammer

In this correspondence, we consider an amplify-and-forward relay network in which relayed information is overheard by an eavesdropper. In order to confound the eavesdropper, a wireless-powered jammer is also considered which harvests energy from a multiple-antenna source. We proposed a new secure beamforming scheme in which beamforming vector is a linear combination of the energy beamforming (EB) and information beamforming (IB) vectors. We also present a new closed-form solution for the proposed beamforming vector which is shown to achieve a higher secrecy rate as compared to the trivial EB and IB vectors. Moreover, a tight closed-form approximation for the ergodic secrecy rate is also derived for the asymptotic regime of a large number of antennas at the source. Finally, numerical examples and simulations are provided which validate our analytical results.