Optimal Bilinear Equalizer for Cell-Free Massive MIMO Systems over Correlated Rician Channels
<|reference_start|>Optimal Bilinear Equalizer for Cell-Free Massive MIMO Systems over Correlated Rician Channels: 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.<|reference_end|>
@article{wang2024optimal,
    title={Optimal Bilinear Equalizer for Cell-Free Massive MIMO Systems over
  Correlated Rician Channels},
    author={Zhe Wang, Jiayi Zhang, Emil Bj"ornson, Dusit Niyato, Bo Ai},
    journal={arXiv preprint arXiv:2407.18531},
    year={2024},
    archivePrefix={arXiv},
    eprint={2407.18531},
    primaryClass={eess.SP cs.IT math.IT}
}