Multiple Eavesdropper-Based Physical Layer Security in TAS/MRC System With Antenna Correlation

In this paper, we analyze the impact of the antenna correlation on the secrecy of multiple-input multiple-output (MIMO) wiretap channels with multiple eavesdroppers, where transmit antenna selection (TAS) and maximal-ratio combining (MRC) are employed at the transmitter, receiver and eavesdroppers, respectively. For the practical passive eavesdropping, we first develop new and closed general formulas for the secrecy outage probability and the probability of non-zero secrecy capacity to characterize the effect of spatial correlation, and results prove that the enhanced security performance can be achieved when multiple antennas are provided at the transmitter. We then explore how spatial correlation affects the asymptotic secrecy outage probability, and the secrecy diversity order is revealed. Based on these, the results show that when the average SNR of the main channel is relatively low, higher antenna correlation is more perfect to the secrecy. When the average SNR of the main channel is relatively high, higher antenna correlation is more destructive to the secrecy.