  In this work, we consider the use of buffer-aided relays, linear precoding
techniques and multiple antennas for physical-layer security in wireless
networks. We develop relay selection algorithms to improve the secrecy-rate
performance of cooperative multi-user multiple-antenna wireless networks. In
particular, we propose a novel finite buffer-aided relay selection algorithm
that employs the maximum likelihood (ML) criterion to select sets of relays
which fully exploit the flexibility offered by relay nodes equipped with
buffers. Numerical results show the benefits of the proposed techniques as
compared to prior art.
