PHY Security Enhancement of Threshold-Based User Selection in Co-Channel Interference Environment

This paper investigates the secrecy performance of a multiuser threshold-based transmit antenna selection scheme (TAS/tSD) in the presence of co-channel interference (CCI) signals and the existence of a passive eavesdropping node. In particular, an exact closed-form expression for the secrecy outage probability is derived. Then, the asymptotic secrecy outage closed-form expression is obtained at the high signal-to-noise ratio (SNR) values. Based on the obtained asymptotic analysis, an optimization problem for power allocation is formulated and solved to improve the secrecy performance of the system concerning minimizing the asymptotic secrecy outage probability. Numerical and simulation results are obtained to justify the obtained analysis.