Characterization of Closely‐Located Users in Measured Cell‐Free Massive MIMO Networks
Abstract
This letter investigates the spatial separability of closely-located users in cell-free massive multiple-input multiple-output (CF-mMIMO) systems using high-diversity real-world channel measurements. We evaluate the orthogonality of four closely-located users under various CF topologies. To ensure a fair comparison, a constant aggregate number of 64 transmit antennas is maintained across all configurations. Our results demonstrate that transitioning from a co-located to a distributed architecture significantly enhances spatial multiplexing: increasing the number of access points (APs) from one to eight reduces both the median channel correlation and the condition number by approximately 50%, while the median spectral efficiency is increased by 5%-6.7% from one to four APs. However, scaling beyond these thresholds results in a performance saturation, as additional APs contribute negligible power due to decreasing large-scale fading coefficients. These findings suggest that excessive AP densification leads to marginal improvements, highlighting a practical trade-off between spatial diversification and the effective signal strength of additional distributed APs.
Related
- Diffractive optical-digital neural networks for robust EUV mask phase-defect characterization and classification
- Modal interactions in strongly nonlinear coupled oscillators with closely spaced modes and nonclassical damping distribution
- Repeated evolution of convergent iridescence in closely related species of Morpho butterflies living in sympatry
- Analysis of image quality degradation in freeform off-axis reflective systems based on measured local sag deviations
- Understanding the high-resolution spectral signatures of Ar-D2O in the 3OD stretch region measured by cavity ringdown absorption spectroscopy
BibTeX
@article{nixarlidis2026characterization,
title = {{Characterization of Closely‐Located Users in Measured Cell‐Free Massive MIMO Networks}},
author = {Dimitrios Georgios Nixarlidis and Eric Pierre Simon and Davy Gaillot and Valentin Picquet and Pierre Laly and Joumana Farah},
journal = {Electronics Letters},
year = {2026},
month = oct,
doi = {10.1049/ell2.70734},
url = {https://hal.science/hal-05820914v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Characterization of Closely‐Located Users in Measured Cell‐Free Massive MIMO Networks
AU - Dimitrios Georgios Nixarlidis
AU - Eric Pierre Simon
AU - Davy Gaillot
AU - Valentin Picquet
AU - Pierre Laly
AU - Joumana Farah
PY - 2026
DA - 2026/10/07
JO - Electronics Letters
DO - 10.1049/ell2.70734
UR - https://hal.science/hal-05820914v1
AB - This letter investigates the spatial separability of closely-located users in cell-free massive multiple-input multiple-output (CF-mMIMO) systems using high-diversity real-world channel measurements. We evaluate the orthogonality of four closely-located users under various CF topologies. To ensure a fair comparison, a constant aggregate number of 64 transmit antennas is maintained across all configurations. Our results demonstrate that transitioning from a co-located to a distributed architecture significantly enhances spatial multiplexing: increasing the number of access points (APs) from one to eight reduces both the median channel correlation and the condition number by approximately 50%, while the median spectral efficiency is increased by 5%-6.7% from one to four APs. However, scaling beyond these thresholds results in a performance saturation, as additional APs contribute negligible power due to decreasing large-scale fading coefficients. These findings suggest that excessive AP densification leads to marginal improvements, highlighting a practical trade-off between spatial diversification and the effective signal strength of additional distributed APs.
SN - 0013-5194
SN - 1350-911X
ER -