Secrecy Outage Performance Analysis of Massive MIMO Transmission with Multiple Non-Colluding Eavesdroppers and Partial Legitimate User CSI

Random unitary beamforming (RUB) can reduce the implementation complexity of massive multiple- input singleoutput (MIMO) downlink transmission by only requiring partial channel state information (CSI) at the transmitter. In this paper, we investigate the secrecy performance of a single- cell massive MIMO system with RUB in the presence of multiple noncolluding eavesdroppers. Specifically, we derive the closed-form expressions of the secrecy outage probability (SOP) for a massive MIMO transmission and its single legitimate user case. Numerical results are presented to illustrate the performance-complexity tradeoff among RUB based, zero-forcing (ZF) beamforming based, and maximum ratio transmission (MRT) based massive MIMO transmission schemes. We show that RUB based scheme can enhance secrecy performance of massive MIMO transmission with lower implementation complexity.