Optimal Bilinear Equalizer for Cell-Free Massive MIMO Systems over Correlated Rician Channels
Published in arXiv, 2024
Abstract: In this paper, we explore the low-complexity optimal bilinear equalizer (OBE) combining scheme design for cell-free massive multiple-input multiple-output networks with spatially correlated Rician fading channels. We provide a spectral efficiency (SE) performance analysis framework for both the centralized and distributed processing schemes with bilinear equalizer (BE)-structure combining schemes applied. The BE-structured combining is a set of schemes that are constructed by the multiplications of channel statistics-based BE matrices and instantaneous channel estimates. Notably, we derive closed-form achievable SE expressions for centralized and distributed BE-structured combining schemes. We propose one centralized and two distributed OBE schemes: Centralized OBE (C-OBE), Distributed OBE based on Global channel statistics (DG-OBE), and Distributed OBE based on Local channel statistics (DL-OBE), which maximize their respective SE expressions. OBE matrices in these schemes are tailored based on varying levels of channel statistics. Notably, we obtain new and insightful closed-form results for the C-OBE, DG-OBE, and DL-OBE combining schemes. Numerical results demonstrate that the proposed OBE schemes can achieve excellent SE, even in scenarios with severe pilot contamination.
Index Terms: Cell-free massive MIMO, beamforming design, optimal bilinear equalizer, pilot contamination
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Recommended citation: Zhe Wang, Jiayi Zhang, Emil Björnson, Dusit Niyato, Bo Ai, "Optimal Bilinear Equalizer for Cell-Free Massive MIMO Systems over Correlated Rician Channels," arxiv: 2407.18531, 2024. https://arxiv.org/pdf/2407.18531