Beamforming Codebook Design for Near-Field Communications in XL-MIMO Systems

초록

We propose a codebook design framework to enable near-field beamforming in extremely-large-scale MIMO systems. The far-field beamforming codebook is designed by accounting for the angular distribution of user locations. The near-field beam-focusing codebook is derived from analytical results under a uniform spherical wave propagation model to mitigate distortion due to nonlinear phase shifts in near-field channels. The proposed framework integrates the design processes of both far-field beamforming and near-field beam-focusing codebooks. Numerical simulations confirm that the proposed codebook improves beamforming gains by reducing distortions associated with spherical wave propagation in the near-field region.

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