EM Exposure Aware Transmission Design for Hybrid RIS and DMA Assisted Multiuser MIMO Uplink

Abstract

We investigate the electromagnetic (EM) exposure constrained spectral efficiency (SE) optimization design in uplink multiuser multiple-input multiple-output (MIMO) communications assisted by the reconfigurable intelligent surface (RIS) and dynamic metasurface antennas (DMAs). By adopting the alternating optimization (AO) method, the transmit covariance, RIS phase shift, and DMA weight matrices are jointly optimized. Specifically, we propose a modified SE maximization water-filling algorithm to obtain the optimal solutions of transmit covariance matrices. Then, the optimization of the RIS phase shift matrix is addressed via exploiting the weighted minimum mean square error, block coordinate descent, and minorize-maximization methods. Furthermore, we express the closed form solution of the unconstrained DMA weight matrix optimization problem and then design the DMA weights satisfying the constraint through an AO algorithm. Numerical results indicate the effectiveness of our proposed EM exposure aware SE maximization transmission scheme over the conventional algorithms.