A Secure Relay Selection AN-Aided Scheme for Dual-Hop DF Relay Networks With Two-Sided Eavesdropping

We propose a new relay selection artificial-noise (AN)-aided scheme to enhance the security of relay networks. We assume the presence of two multi-antenna eavesdroppers where one of them is closer to the legitimate transmitter (Alice) and the other one is closer to the legitimate receiver (Bob). To improve the system's security, we optimize the transmit power allocation factor between data and AN. Moreover, we design the data and AN precoders at Alice, the AN precoder at Bob, the AN precoder at the relays, and data receive filter at Bob. We derive closed-form expressions for the links' rates and the instantaneous secrecy rate. Numerical results show that our proposed scheme achieves higher average secrecy rate than others in the literature.