Performance of Network-Assisted Full-Duplex for Cell-Free Massive MIMO

TLDR

The study investigates the spectral efficiency of network‑assisted full‑duplex communications in cell‑free massive MIMO with imperfect CSI and proposes a genetic‑algorithm based scheduling strategy to mitigate uplink‑to‑downlink interference. Using large‑dimensional random‑matrix theory, the authors derive deterministic equivalents for uplink and downlink sum‑rates with MMSE, ZF, and RZF receivers, compare spectral efficiencies across in‑band full‑duplex and half‑duplex duplexing, and introduce the genetic‑algorithm scheduling strategy. Numerical simulations confirm that the derived deterministic equivalents accurately predict system performance, that downlink‑to‑uplink interference cancellation and the genetic‑algorithm scheduling strategy substantially improve uplink and downlink spectral efficiencies, and that half‑duplex remote antenna units outperform full‑duplex configurations when the total number of antennas is fixed.

Abstract

In this paper, the spectral efficiency of network assisted full-duplex communications (NAFD) in cell-free (CF) massive multiple-input multiple-output (MIMO) network with imperfect channel state information is investigated under spatial correlated channels. Based on large dimensional random matrix theory, the deterministic equivalents for the uplink sum-rate with minimum-mean-square-error receiver as well as the downlink sum-rate with zero-forcing and regularized zero-forcing beamforming are presented. Numerical results show that under various environmental settings, the deterministic equivalents are accurate in both a large-scale system and system with a finite number of antennas. It is also shown that with the downlink-to-uplink interference cancellation, the uplink spectral efficiency of CF massive MIMO with NAFD could be improved. The spectral efficiencies of NAFD with different duplex configurations such as in-band full-duplex, and half-duplex are compared. With the same total numbers of transmit and receive antennas, NAFD with half-duplex remote antenna units offers a higher spectral efficiency. To alleviate the uplink-to-downlink interference, a novel genetic algorithm based user scheduling strategy (GAS) is proposed. Simulation results show that the achievable downlink sum-rate by using the GAS is greatly improved compared to that by using the random user scheduling.