SWIPT-enabled Cell-free Millimeter-wave MIMO with Multiple IRSs.

In this paper, we investigate a simultaneous wireless information and power transfer (SWIPT)-enabled cell-free millimeter-wave multiple-input multiple-output (MIMO) system. Therein, multiple base stations (BSs) serve multiple users by using the SWIPT based on power-splitting (PS) protocol. To further improve the system throughput and harvested energy, multiple intelligent reflecting surfaces (IRSs) are deployed. We formulate an optimization problem that aims to optimize the beamformers of the BSs, phase shifts of the IRSs, and PS factors at users to maximize the minimum energy efficiency of the users. The max-min energy efficiency optimization problem is computationally intractable, and we propose an alternating descent algorithm to solve it with low computational complexity. Simulation results demonstrate the effectiveness of the proposed algorithm.