Intelligent Reflecting Surface Enabled Random Rotations Scheme for the MISO Broadcast Channel

The current literature on intelligent reflecting surface (IRS) focuses optimizing the IRS phase shifts to yield coherent beamforming gains, under assumption of perfect channel state information (CSI) individual IRS-assisted links, which is highly impractical. This work, instead, considers random rotations scheme at in elements only employ without requiring any CSI. CSI then needed base station (BS) overall implement transmission scheme. Under this framework, we derive sum-rate scaling laws large number users regime for multiple-input single-output (MISO) broadcast channel, with optimal dirty paper coding (DPC) and lower-complexity (RBF) deterministic (DBF) schemes BS. increases by exploiting multi-user diversity, but also compromises gain some extent due correlation. Finally, energy efficiency maximization problems terms BS antennas, transmit power are solved using derived laws. Simulation results show proposed improve sum-rate, performance becoming close that a users.