Hybrid Precoding for Mixture Use of Phase Shifters and Switches in mmWave Massive MIMO

TL;DR

This paper introduces a hybrid precoding architecture using variable-phase shifters and switches for mmWave massive MIMO, along with efficient algorithms to optimize spectral efficiency while reducing complexity.

Contribution

It proposes a novel VPS-based hybrid precoding architecture and develops low-complexity algorithms, including a group-connected design, for improved efficiency and hardware simplicity.

Findings

Achieves satisfactory spectral efficiency with reduced complexity.

Proposes a group-connected architecture for hardware efficiency.

Develops closed-form solutions for fast implementation.

Abstract

A variable-phase-shifter (VPS) architecture with hybrid precoding for mixture use of phase shifters and switches, is proposed for millimeter wave massive multiple-input multiple-output communications. For the VPS architecture, a hybrid precoding design (HPD) scheme, called VPS-HPD, is proposed to optimize the phases according to the channel state information by alternately optimizing the analog precoder and digital precoder. To reduce the computational complexity of the VPS-HPD scheme, a low-complexity HPD scheme for the VPS architecture (VPS-LC-HPD) including alternating optimization in three stages is then proposed, where each stage has a closed-form solution and can be efficiently implemented. To reduce the hardware complexity introduced by the large number of switches, we consider a group-connected VPS architecture and propose a HPD scheme, where the HPD problem is divided into multiple independent subproblems with each subproblem flexibly solved by the VPS-HPD or VPS-LC-HPD scheme. Simulation results verify the effectiveness of the propose schemes and show that the proposed schemes can achieve satisfactory spectral efficiency performance with reduced computational complexity or hardware complexity.