Secure Communication For Buffer-aided Two-hop System

This paper investigates the link selection policy for secure communication over a bufferaided two-hop communication link.It is assumed that a source wishes to send information to a destination with the aid of a trusted half-duplex relay node compromised by a passive eavesdropper,and that there is no direct link between the source and the destination.The buffer-aided relay forwards the information to the destination by employing the decode-and-forward(DF)scheme.Both the source and the relay transmissions are assumed to be vulnerable to the eavesdropper.The perfect channel state information(CSI)of the network is assumed to be available at the source and the relay.Initially,conventional relaying protocols where equal partition of the time for the reception and transmission of the relay is considered.Then,the optimal time fraction with the optimal power control policy that maximizes the secrecy throughput is identified.Moreover,the optimal joint link selection and power control policy that maximizes the secrecy throughput is derived.Consequently,a low complex and asymptotically optimal link selection with on/off power control is then proposed.Numerical results demonstrate that the proposed link selection policies with power control can significantly improve the achievable secrecy throughput of the buffer-aided two-hop communication system.