Smart Hybrid Beamforming and Pilot Assignment for 6G Cell-Free Massive MIMO

TL;DR

This paper proposes a hybrid beamforming and pilot assignment strategy for 6G cell-free massive MIMO, optimizing spectral efficiency and network performance while reducing hardware complexity.

Contribution

It introduces a novel joint optimization framework for hybrid beamforming and pilot assignment in cell-free massive MIMO networks, with derived asymptotic spectral efficiency expressions.

Findings

Optimized beamforming and pilot assignment significantly improve spectral efficiency.

Hybrid transceivers reduce hardware complexity compared to fully digital systems.

Simulation results confirm performance gains from the proposed optimization.

Abstract

This paper investigates Cell-Free massive MIMO networks, where each access point (AP) is equipped with a hybrid transceiver, reducing the complexity and cost compared to a fully digital transceiver. Asymptotic approximations for the spectral efficiency are derived for uplink and downlink. Capitalizing on these expressions, a max-min problem is formulated to optimize the (i) analog beamformer at the APs and (ii) pilot assignment. Simulations show that the optimization of these variables substantially increases the network performance.