Spectral Efficiency Optimization for mmWave Wideband MIMO RIS-assisted Communication

TL;DR

This paper proposes a joint optimization framework for power allocation and RIS phase shifts in wideband mmWave MIMO systems, enhancing link performance with new modeling and an efficient gradient ascent algorithm.

Contribution

It introduces a comprehensive system model including pathloss and blockage effects, and develops a gradient ascent algorithm for co-design of power and RIS phases in 28 GHz MIMO systems.

Findings

Improved system modeling with realistic propagation effects.

Development of an efficient gradient ascent co-design algorithm.

Complexity analysis demonstrating scalability of the proposed method.

Abstract

Reconfigurable Intelligent Surfaces (RIS) are passive or semi-passive heterogeneous metasurfaces and consist of many tunable elements. RIS is gaining momentum as a promising new technology to enable transforming the propagation environment into controllable parameters. In this paper, we investigate the co-design of per-subcarrier power allocation matrices and multielement RIS phase shifts in downlink wideband MIMO transmission using 28 GHz frequency bands. Our contributions in improving RIS-aided links include (1) enhanced system modeling with pathloss and blockage modeling, and uniform rectangular array (URA) design, (2) design of gradient ascent co-design algorithm, and (3) asymptotic (Big O) complexity analysis of proposed algorithm and runtime complexity evaluation.