Network-Assisted Full-Duplex Cell-Free Massive MIMO Systems Under Infeasible Circumstances

TL;DR

This paper investigates full-duplex cell-free massive MIMO systems, deriving spectral efficiency expressions and proposing an adaptive algorithm for power and mode optimization under challenging conditions.

Contribution

It introduces a closed-form spectral efficiency analysis and a differential evolution-based algorithm for joint power and mode allocation in full-duplex cell-free MIMO networks.

Findings

The spectral efficiency expressions are validated through simulations.

The proposed algorithm outperforms benchmarks in spectral efficiency and fairness.

Some UEs may remain unscheduled under severe conditions.

Abstract

Cell-free massive multiple-input multiple-output is a potential candidate for future networks with pervasive connectivity by utilizing coherent joint transmission and distributed antenna arrays. This paper studies the exploitation of full-duplex communication for a distributed antenna array. Specifically, we derive a closed-form expression for the uplink and downlink ergodic spectral efficiency (SE) for a network where the APs can flexibly operate in either the full-duplex or half-duplex mode with linear processing and Rayleigh fading channels. A long-term total SE maximization problem is formulated subject to a network operation model and individual SE requirements with limited power budget. Due to the intrinsic nonconvexity and infeasible circumstances where some UEs might not be able to achieve the rate requirements, we adapt differential evolution to design a low computational complexity algorithm that can attain good power allocation and network operation mode in polynomial time. Numerical results demonstrate the effectiveness of our system design and proposed algorithm over state-of-the-art benchmarks with satisfactory service to the majority of UEs, although several ones may be unscheduled under harsh conditions.