# What is the Most Efficient Technique for Uplink Cell-Free Massive MIMO?

## TL;DR

This paper compares various uplink techniques for cell-free massive MIMO, establishing a unified framework and optimization strategy to identify the most efficient method considering fairness, capacity, signaling, and complexity.

## Contribution

It introduces a unified analytical framework and a universal power control strategy to evaluate and identify the optimal uplink technique for practical deployments.

## Key findings

- Identifies the most efficient uplink technique based on comprehensive metrics.
- Provides a unified analytical approach applicable to diverse system configurations.
- Offers insights into trade-offs among fairness, capacity, signaling, and complexity.

## Abstract

This paper seeks to determine the most efficient uplink technique for cell-free massive MIMO systems. Despite offering great advances, existing works suffer from fragmented methodologies and inconsistent assumptions (e.g., single- vs. multi-antenna access points, ideal vs. spatially correlated channels). To address these limitations, we: (1) establish a unified analytical framework compatible with centralized/distributed processing and diverse combining schemes; (2) develop a universal optimization strategy for max-min power control; and (3) conduct a holistic study among four critical metrics: worst-case user spectral efficiency (fairness), system capacity, fronthaul signaling, and computational complexity. Through analyses and evaluation, this work ultimately identifies the optimal uplink technique for practical cell-free deployments.