Robust Beamforming Design for IRS-Assisted MIMO Systems with Imperfect Channels

In this paper, large-scale intelligent reflecting surface (IRS)-assisted multiple-input multiple-output (MIMO) system is considered in the presence of channel uncertainty. To maximize the average sum rate of the system by jointly optimizing the active beamforming at the BS and the passive phase shifts at the IRS, while satisfying the power constraints, a novel robust beamforming design is proposed by using the penalty dual decomposition (PDD) algorithm. In each iteration of this algorithm, the optimal solution for each variable can be obtained with closed-form expression. The convergence of this algorithm is also proved. Simulation results show that the proposed scheme achieves high performance with very low computational complexity.