Outage-Constrained Robust Beamforming for Intelligent Reflecting Surface Aided Wireless Communication

In intelligent reflecting surface (IRS) aided wireless communication systems, channel state information (CSI) is crucial to achieve its promising passive beamforming gains. However, CSI errors are inevitable in practice and generally correlated over the IRS elements due limited training with discrete phase shifts, which degrade data transmission rate reliability. this paper, we focus on investigating effect of outage performance an IRS-aided multiuser downlink system. Specifically, aim jointly optimize active transmit precoding vectors at access point (AP) shifts minimize AP's power, subject constraints maximum CSI-error induced probability for users. First, consider single-user case derive user's terms mean signal power (MSP) variance received user. Since there a trade-off tuning these two parameters probability, propose maximize their weighted sum optimal weight found by one-dimensional search. Then, general case, since users' probabilities difficult obtain closed-form inter-user interference, novel constrained stochastic successive convex approximation (CSSCA) algorithm, replaces non-convex properly designed surrogate approximations. Simulation results verify effectiveness proposed robust beamfoming algorithms show significant improvement various benchmark schemes.