TY - GEN
T1 - Hybrid Digital-Wave Beamforming for Cell-Free Massive MIMO Systems With Fronthaul Compression
AU - Park, Eunhyuk
AU - Park, Seok Hwan
AU - Simeone, Osvaldo
AU - Di Renzo, Marco
N1 - Publisher Copyright:
© 2025 IEEE.
PY - 2025
Y1 - 2025
N2 - Stacked intelligent metasurfaces (SIMs), which are composed of multi-layer programmable metasurfaces, support beamforming in the wave domain, utilizing a limited number of radio frequency (RF) chains. This work investigates the application of SIMs in the downlink of cell-free massive multiple-input multiple-output systems with finite-capacity fronthaul links. Specifically, we address the joint optimization of fronthaul compression and hybrid digital and wave-domain beamforming. To tackle the resulting highly non-convex problem, an alternating optimization algorithm is proposed, which iteratively optimizes digital processing and wave beamforming variables. Numerical results demonstrate that the proposed method outperforms baseline schemes relying solely on digital or wave beamforming, achieving near fully-digital performance with a few RF chains, assuming a sufficiently high signal-to-noise ratio (SNR).
AB - Stacked intelligent metasurfaces (SIMs), which are composed of multi-layer programmable metasurfaces, support beamforming in the wave domain, utilizing a limited number of radio frequency (RF) chains. This work investigates the application of SIMs in the downlink of cell-free massive multiple-input multiple-output systems with finite-capacity fronthaul links. Specifically, we address the joint optimization of fronthaul compression and hybrid digital and wave-domain beamforming. To tackle the resulting highly non-convex problem, an alternating optimization algorithm is proposed, which iteratively optimizes digital processing and wave beamforming variables. Numerical results demonstrate that the proposed method outperforms baseline schemes relying solely on digital or wave beamforming, achieving near fully-digital performance with a few RF chains, assuming a sufficiently high signal-to-noise ratio (SNR).
KW - Cell-free massive MIMO
KW - hybrid digital-wave beamforming
KW - optimization
KW - stacked intelligent metasurface
UR - https://www.scopus.com/pages/publications/105030540436
U2 - 10.1109/PIMRC62392.2025.11275192
DO - 10.1109/PIMRC62392.2025.11275192
M3 - Conference paper
AN - SCOPUS:105030540436
T3 - IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC
BT - 2025 IEEE 36th International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2025
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 36th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2025
Y2 - 1 September 2025 through 4 September 2025
ER -