Artificial Noise Aided Secrecy Enhancement in Amplify-and-Forward Relay Networks

Cooperative relaying and cooperative jamming have been used to improve the secrecy of wireless networks. In this paper, Artificial Noise (AN) based secrecy enhancement of a dual-hop wireless network consisting of 'n' amplify-and-forward (AF) relays in the presence of a passive eavesdropper (E) is studied. A practical setting where direct links exist between source-destination (S-D) and source-eavesdropper (S-E) is considered. The source allocates some of its available power to transmit AN in order to confuse the eavesdropper and thereby degrades its channel. The optimum power allocation factor (a) and maximum secrecy rate are estimated analytically and by simulation. The performance is evaluated based on secrecy rate (R-s) and bit error rate (BER); for the case of randomly distributed relays and for any eavesdropper location. Numerical results show the improvement of the proposed cooperative scheme over other schemes.