Secrecy Outage Analysis of Transmit Antenna Selection with Switch-and-Examine Combining over Rayleigh Fading

In this paper, we contribute to the secrecy outage analysis of transmit antenna selection (TAS) with switch-and-examine combining (SEC) in the Multiple-input multiple-output (MIMO) wiretap channel. The complexity of SEC is lower than maximum-ratio combining (MRC) and selection combining (SC). The transmit antenna which maximizes the instantaneous signal-to-noise ratio (SNR) at the receiver is selected. Two scenarios are studied here: 1) SEC at both the receiver´s side and the eavesdropper´s side (SEC/SEC); 2) SEC at the receiver´s side while MRC at the eavesdropper´s side (SEC/MRC). Expressions for the exact and asymptotic secrecy outage probability are derived and validated by simulation results. It is demonstrated that SEC may achieve competitive secrecy performance in the low SNR regime with less estimation cost. In the high SNR regime, it achieves full secrecy diversity order NaNb with careful threshold´s design even under the condition of MRC applied at the eavesdropper.