User-centric Handover in mmWave Cell-Free Massive MIMO with User Mobility

TL;DR

This paper explores user-centric handover strategies in mmWave cell-free massive MIMO systems with user mobility, addressing channel aging and proposing beamforming and association techniques to improve performance.

Contribution

It introduces a new mmWave channel model considering mobility and channel aging, and proposes beamforming and dynamic user association methods for mobile scenarios.

Findings

Proposed beamforming techniques improve signal quality.

Dynamic user association enhances handover efficiency.

Numerical results confirm effectiveness of the methods.

Abstract

The coupling between cell-free massive multiple-input multiple-output (MIMO) systems operating at millimeter-wave (mmWave) carrier frequencies and user mobility is considered in this paper. First of all, a mmWave channel is introduced taking into account the user mobility and the impact of the channel aging. Then, three beamforming techniques are proposed in the considered scenario, along with a dynamic user association technique (handover): starting from a user-centric association between each mobile device and a cluster of access points (APs), a rule for updating the APs cluster is formulated and analyzed. Numerical results reveal that the proposed beamforming and user association techniques are effective in the considered scenario.