RIS-Assisted D-MIMO for Energy-Efficient 6G Indoor Networks

TL;DR

This paper introduces an optimization framework for RIS-assisted D-MIMO systems to enhance energy efficiency in 6G indoor networks, jointly optimizing power and RIS configurations under realistic constraints.

Contribution

It presents a novel joint optimization approach for power and RIS phase configurations in D-MIMO systems, addressing both coherent and non-coherent modes with practical constraints.

Findings

Proposed scheme outperforms baseline methods in energy efficiency.

RIS phase-shift optimization significantly improves system performance.

Insights into RIS size and control architecture impact on energy efficiency.

Abstract

We propose an alternating optimization framework for maximizing energy efficiency (EE) in reconfigurable intelligent surface (RIS) assisted distributed MIMO (D-MIMO) systems under both coherent and non-coherent reception modes. The framework jointly optimizes access point (AP) power allocation and RIS phase configurations to improve EE under per-AP power and signal-to-interference-plus-noise ratio (SINR) constraints. Using majorization-minimization for power allocation together with per-element RIS adaptation, the framework achieves tractable optimization of this non-convex problem. Simulation results for indoor deployments with realistic power-consumption models show that the proposed scheme outperforms equal-power and random-scatterer baselines, with clear EE gains. We evaluate the performance of both reception modes and quantify the impact of RIS phase-shift optimization, RIS controller architectures (centralized vs. per-RIS control), and RIS size, providing design insights for practical RIS-assisted D-MIMO deployments in future 6G networks.