RIS-Aided Angular-Based Hybrid Beamforming Design in mmWave Massive MIMO Systems

TL;DR

This paper introduces a RIS-assisted hybrid beamforming approach for mmWave massive MIMO systems, optimizing system performance by combining angular-based beamforming with intelligent surface phase adjustments.

Contribution

It presents a novel three-stage RIS-AB-HBF architecture that reduces RF chain complexity and channel estimation overhead using angular parameters and PSO-based RIS phase shift optimization.

Findings

Enhanced system reliability and flexibility with RIS integration.

Significant performance improvements demonstrated through simulations.

Efficient beamforming design leveraging angular channel information.

Abstract

This paper proposes a reconfigurable intelligent surface (RIS)-aided and angular-based hybrid beamforming (AB-HBF) technique for the millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems. The proposed RIS-AB-HBF architecture consists of three stages: (i) RF beamformer, (ii) baseband (BB) precoder/combiner, and (iii) RIS phase shift design. First, in order to reduce the number of RF chains and the channel estimation overhead, RF beamformers are designed based on the 3D geometry-based mmWave channel model using slow time-varying angular parameters of the channel. Second, a BB precoder/combiner is designed by exploiting the reduced-size effective channel seen from the BB stages. Then, the phase shifts of the RIS are adjusted to maximize the achievable rate of the system via the nature-inspired particle swarm optimization (PSO) algorithm. Illustrative simulation results demonstrate that the use of RISs in the AB-HBF systems has the potential to provide more promising advantages in terms of reliability and flexibility in system design.