  This letter proposes a novel hybrid half-/full-duplex relaying scheme to
enhance the relay channel security. A source node (Alice) communicates with her
destination node (Bob) in the presence of a buffer-aided full-duplex relay node
(Rooney) and a potential eavesdropper (Eve). Rooney adopts two different
relaying strategies, namely randomize-and-forward and decode-and-forward
relaying strategies, to improve the security of the legitimate system. In the
first relaying strategy, Rooney uses a codebook different from that used at
Alice. In the second relaying strategy, Rooney and Alice use the same
codebooks. In addition, Rooney switches between half-duplex and full-duplex
modes to further enhance the security of the legitimate system. The numerical
results demonstrate that our proposed scheme achieves a significant average
secrecy end-to-end throughput improvement relative to the conventional
bufferless full-duplex relaying scheme.
