Secrecy analysis for selection among transmit antennas with unequal average SNR performance

This paper presents a general analytical framework to evaluate the secrecy performance of transmit antenna selection (TAS) systems without requiring the identical average signal-to-noise ratios (SNRs) from different transmit antennas. Closed-form expressions of secrecy outage probability are derived in a multiple-input multiple-output (MIMO) wiretap channel. Moreover, a novel TAS scheme based on the limited feedback from both the receiver and the eavesdropper is proposed and analysed. With the additional consideration of the eavesdropper´s channel, security is shown to be enhanced although the instantaneous channel state information (CSI) keeps unknown to the transmitter. Finally, numerical results substantiate the aforementioned analysis.