Secrecy analysis of multi-cell massive MIMO systems with RCI precoding and artificial noise transmission

In this paper, we study linear precoding for a secure multi-cell massive multiple-input multiple-output (MIMO) downlink system employing artificial noise generation. We consider the large system limit where the number of base station antennas, the number of mobile users, and the number of eavesdropper antennas are all growing without bound but with fixed ratio. The proposed precoder is based on regularized channel inversion (RCI) with regularization parameter κ. The optimal κ is derived such that the ergodic secrecy rate is maximized in the case of imperfect channel state information at the transmitter due to pilot contamination. Our analytical results show that the proposed RCI precoder outperforms other linear precoders.