Harnessing Mutual Coupling in Cell-Free mMIMO
Abstract
This letter investigates a cell-free massive MIMO system with L access points (APs), each employing a small fixed-form-factor, uniform linear array of N potentially closely spaced antennas. Utilizing multiport communication theory, we analyze the impact of mutual coupling on uplink and downlink spectral efficiency (SE) under various impedance-matching strategies. We compare two deployment regimes: (i) increasing N while L is kept fixed, and (ii) increasing N while fixing the total antenna count M = NL. Numerical results show that, with a full matching network, mutual coupling itself becomes beneficial when an AP serves several user equipments, which is the typical operating regime of user-centric cell-free networks. Furthermore, with full matching, antenna densification can enhance SE or allow for a reduction in the number of APs without performance loss. Since full matching networks remain of manageable size in the small arrays of distributed APs, unlike in large centralized arrays, cell-free networks offer a natural setting for exploiting mutual coupling.
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BibTeX
@misc{tufa2026harnessing,
title = {{Harnessing Mutual Coupling in Cell-Free mMIMO}},
author = {Erind Tufa and Antonio A. D'Amico and Luca Sanguinetti},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.03193},
eprint = {2611.03193},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.03193},
}
RIS
TY - UNPB
TI - Harnessing Mutual Coupling in Cell-Free mMIMO
AU - Erind Tufa
AU - Antonio A. D'Amico
AU - Luca Sanguinetti
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.03193
UR - https://arxiv.org/abs/2611.03193
AB - This letter investigates a cell-free massive MIMO system with L access points (APs), each employing a small fixed-form-factor, uniform linear array of N potentially closely spaced antennas. Utilizing multiport communication theory, we analyze the impact of mutual coupling on uplink and downlink spectral efficiency (SE) under various impedance-matching strategies. We compare two deployment regimes: (i) increasing N while L is kept fixed, and (ii) increasing N while fixing the total antenna count M = NL. Numerical results show that, with a full matching network, mutual coupling itself becomes beneficial when an AP serves several user equipments, which is the typical operating regime of user-centric cell-free networks. Furthermore, with full matching, antenna densification can enhance SE or allow for a reduction in the number of APs without performance loss. Since full matching networks remain of manageable size in the small arrays of distributed APs, unlike in large centralized arrays, cell-free networks offer a natural setting for exploiting mutual coupling.
ER -