A Novel Dynamic Hybrid Beamforming Design for ELAA Systems

Extremely large-scale antenna array (ELAA) is deemed as one of several key candidate technologies for the sixth generation (6G) mobile networks. Nevertheless, the near-field effect poses a significant challenge for ELAA systems as a result of employing a substantial quantity of antennas for the transmission of high-frequency signals. Furthermore, the practical implementation of ELAA by employing a hybrid beamforming framework boosts the impact of the near-field effect on the system performance. In order to effectively address this severe near-field effect, we propose a novel dynamic hybrid beamforming architecture, in which each antenna is either adaptively connected to one radio frequency (RF) chain for signal transmission, or deactivated for power saving. The dynamic hybrid beamforming design algorithm is developed to maximize the achievable sum-rate under the constraints of the constant modulus of phase shifters, non-overlapping dynamic connection network, and the total transmit power. To address the resulting complicated nonconvex design problem, we employ the fractional programming (FP) method to transform the objective function into a more tractable form and exploit the manifold-based algorithm to tackle the nonconvex constraint. The simulation results demonstrate the advantages of the proposed dynamic hybrid beamforming and the effectiveness of the FP-manifold-based algorithm in ELAA near-field communication systems.