Performance Analysis of Secure Communication in Massive MIMO with Imperfect Channel State Information

In recent years, physical layer security has been regarded as a promising concept to provide secure communications in next generation mobile systems, where theoretically massive MIMO can significantly enhance the system secrecy performance due to its advantage in shaping the transmitted signals to null the interference or leakage. However, in practical systems, the channel state information is often imperfect due to the outdated channel effect and the channel estimation error. In this paper, we investigate the physical layer security problem in a multi-user massive MIMO system under imperfect CSI. We first derive a tight asymptotic lower bound of the ergodic system secrecy capacity under imperfect CSI, and then analyze how imperfect CSI affects the system secrecy performance. Simulation results reveal the negative impact of the imperfect CSI on the secrecy performance of massive MIMO systems and the accuracy of our theoretical derivations and analysis.