Rate-Splitting for CF Massive MIMO Systems With Channel Aging

TL;DR

This paper explores rate-splitting in cell-free massive MIMO systems to counteract channel aging effects, proposing a robust precoding scheme and deriving a closed-form spectral efficiency expression to enhance mobile communication performance.

Contribution

It introduces a bisection-based precoding scheme for RS-assisted CF massive MIMO that outperforms existing methods and derives a new closed-form sum spectral efficiency expression.

Findings

RS mitigates interference in mobile CF massive MIMO.

The proposed precoding scheme outperforms superposition-based and random schemes.

Closed-form sum SE expression enhances understanding of system performance.

Abstract

The cell-free (CF) massive multiple-input multiple-output (MIMO) system is considered a cutting-edge technology in next-generation mobile communication due to its ability to provide high-performance coverage seamlessly and uniformly. This paper aims to mitigate the negative impact of channel aging due to the movement of user equipment in CF massive MIMO systems by utilizing rate-splitting (RS) technology. Taking into account the outdated channel state information, we obtain the achievable sum spectral efficiency (SE) of the RS-assisted CF massive MIMO system, where the private messages can directly adopt conventional maximum ratio, local minimum mean square error (MMSE), and centralized MMSE precoding schemes. Moreover, we propose a bisection-based precoding scheme that maximizes the minimum SE of common messages, which outperforms the superposition-based and random precoding schemes and exhibits strong robustness in complex mobile scenarios. Furthermore, we derive a novel closed-form sum SE expression for the considered system. The results demonstrate that RS technology can mitigate interference in mobile CF massive MIMO systems, improving overall system performance.