Secure two-user AF relaying networks using cooperative jamming

In this paper, we investigate secure two-user AF relaying networks based on a destination assisted cooperative jamming (DACJ). We consider two sources, one destination, one eavesdropper and multiple amplify-and-forwards (AF) relays. In the first time slot, each source broadcasts the information signal to the relays. In order to protect the source message from being eavesdropped, the destination simultaneously transmits a jamming signal to each relay. The selected relay amplifies and forwards the combined signal to the destination and eavesdropper. We introduce reactive relay selection and power allocation to decrease the power consumption. Closed-form expressions for lower bound of ergodic secrecy capacity (ESC) are provided. Numerical results are presented to verify the exactness of the proposed mathematical analysis.