Towards High Energy Efficiency for Cell-Free Massive MIMO: A Low-Complexity Approach

In this correspondence, we investigate the energy efficiency (EE) of the uplink in a cell-free massive multiple-input multiple-output (MIMO) system equipped with low-resolution analog-to-digital converters (ADCs). Under the assumption of phase-unaware Ricean fading channels, we derive closed-form expressions for both the achievable rate and EE. Subsequently, we formulate an optimization problem aimed at maximizing EE through the joint design of receiver weights and power control factors. To tackle this non-convex challenge, the alternating optimization method is employed, facilitating the development of low-complexity, closed-form algorithms. These algorithms leverage the generalized eigenvalue, quadratic transformation, and Lagrangian dual transformation techniques. Our numerical results corroborate the theoretical analysis and underscore the efficacy of the proposed EE optimization algorithm.