References & Further Reading

References

H. Q. Ngo, A. Ashikhmin, H. Yang, E. G. Larsson, and T. L. Marzetta, Cell-Free Massive MIMO Versus Small Cells, 2017
The foundational paper on cell-free massive MIMO. Introduces the system model with conjugate beamforming (Level 1) and derives the UatF SINR bound used as the starting point for distributed processing analysis.
E. Bjornson and L. Sanguinetti, Making Cell-Free Massive MIMO Competitive with MMSE Processing and Centralized Implementation, 2020
Introduces the four levels of cooperation (L1–L4) and shows that centralized MMSE (Level 4) significantly outperforms local MRC (Level 1). The primary reference for the cooperation level framework in Section 13.2.
E. Bjornson and L. Sanguinetti, Scalable Cell-Free Massive MIMO Systems, 2020
Formalizes scalable cell-free massive MIMO with user-centric clustering and defines the distributed processing framework. Provides the LSFD analysis used in Section 13.3.
O. T. Demir, E. Bjornson, and L. Sanguinetti, Foundations of User-Centric Cell-Free Massive MIMO, 2021
The comprehensive monograph on cell-free massive MIMO. Chapters 5–7 cover centralized vs. distributed processing, LSFD, and fronthaul-constrained design in full detail.
G. Interdonato, E. Bjornson, H. Q. Ngo, P. Frenger, and E. G. Larsson, Ubiquitous Cell-Free Massive MIMO Communications, 2019
Overview of cell-free massive MIMO with detailed discussion of cooperation levels, pilot assignment, and power control. Provides the taxonomy of local vs. centralized processing used in this chapter.
F. Göttsch and G. Caire, Optimal User Load and Energy Efficiency in User-Centric Cell-Free Massive MIMO, 2023
The CommIT contribution analyzed in Section 13.4. Derives the optimal user load per AP that maximizes energy efficiency in user-centric cell-free networks, accounting for fronthaul power, AP circuit power, and transmit power.
F. Göttsch, M. Sarajlic, and G. Caire, Energy-Efficient User-Centric Cell-Free Massive MIMO: AP Switching and Clustering, 2024
Extends the energy efficiency analysis to include AP on/off switching and dynamic clustering. Shows that turning off underutilized APs can improve network energy efficiency by 30–50 percent.
S. Buzzi and C. D'Andrea, Cell-Free Massive MIMO: User-Centric Approach, 2017
One of the first papers proposing the user-centric approach. Compares local MMSE processing against centralized combining and quantifies the performance gap.
T. L. Marzetta, E. G. Larsson, H. Yang, and H. Q. Ngo, Fundamentals of Massive MIMO, 2016
The textbook on massive MIMO fundamentals. Chapter 4 covers the distributed processing architecture for multi-cell systems that inspired the cell-free paradigm.
E. Bjornson, J. Hoydis, and L. Sanguinetti, Massive MIMO Networks: Spectral, Energy, and Hardware Efficiency, 2017
Comprehensive treatment of massive MIMO performance analysis. Chapters 5–6 cover MMSE processing and energy efficiency metrics that form the basis of the analysis in this chapter.
M. Bashar, K. Cumanan, A. G. Burr, H. Q. Ngo, E. G. Larsson, and P. Xiao, Energy Efficiency of the Cell-Free Massive MIMO Uplink with Optimal Uniform Quantization, 2019
Analyzes fronthaul quantization in cell-free massive MIMO. Derives the optimal quantization bit allocation that minimizes fronthaul load subject to a rate constraint. The primary reference for Section 13.5.
M. Bashar, K. Cumanan, A. G. Burr, H. Q. Ngo, M. Debbah, and P. Xiao, Cell-Free Massive MIMO with Limited Fronthaul, 2020
Comprehensive treatment of limited-fronthaul cell-free massive MIMO. Analyzes both scalar and vector quantization and proposes a joint quantization-power control optimization framework.