# Joint User Scheduling and Precoding for XL-MIMO Systems with Imperfect CSI

## TL;DR

This paper introduces a joint user scheduling and precoding algorithm for XL-MIMO systems that accounts for imperfect CSI, improving spectral efficiency by leveraging long-term channel information and realistic channel conditions.

## Contribution

It presents a novel algorithm that jointly optimizes user selection and precoding in XL-MIMO systems under realistic, imperfect CSI conditions.

## Key findings

- Improved achievable sum spectral efficiency with the proposed method.
- Effective use of long-term CSI for user scheduling.
- Highlighting the importance of considering CSI imperfections in system design.

## Abstract

We propose an algorithm for joint precoding and user selection in multiple-input multiple-output systems with extremely-large aperture arrays, assuming realistic channel conditions and imperfect channel estimates. The use of long-term channel state information (CSI) for user scheduling, and a proper selection of the set of users for which CSI is updated allow for obtaining an improved achievable sum spectral efficiency. We also confirm that the effect of imperfect CSI in the precoding vector design and the cost of training must be taken into consideration for realistic performance prediction.