Security performance of multiple antennas multiple relaying networks with outdated relay selection

We investigate physical-layer security (PLS) for multi-antenna and multi-relay networks with transmit beamforming and relay selection under feedback delay. The connection outage probability (COP) and secrecy outage probability (SOP) are derived to evaluate the reliability and security. Besides, we introduce a novel definition of the reliable-and-secure probability (RSP) to combat the correlation between COP and SOP introduced by the corporate source-relay link. Based on this, to measure the overall efficiency of the system achieving reliable and secure transmission, we further investigate the modified secrecy throughput performance and develop the optimal design of secrecy codeword rate setting to maximize the secrecy throughput. Numerical results verify the analysis and suggest the importance of secrecy codeword rate setting on the security performance.