The paper proposes a hybrid beamforming architecture for RHS-based cell-free networks. The holographic beamformer at each distributed base station is designed based on local channel state information to maximize the channel gain, while the digital beamformer at the central processing unit is designed using the minimum mean squared error criterion based on the overall channel state information.
The theoretical analysis and simulation results show that the phase shift errors at the RHS elements and the hardware impairments at the radio frequency chains of transceivers limit the spectral efficiency in the high signal-to-noise ratio region. However, increasing the number of base stations can compensate for these impairments.
The paper also derives the asymptotic capacity bound for an infinite physical size of the RHS in the near-field channel model, and demonstrates that the ergodic spectral efficiency based on the near-field channel model is higher than that based on the far-field channel model assumption.
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by Qingchao Li,... at arxiv.org 05-03-2024
https://arxiv.org/pdf/2405.01150.pdfDeeper Inquiries