6G超大规模天线阵列近场通信的波束赋形设计

Beamforming Design for Near-field Communications with ExtremelyLarge-scale Antenna Array in 6G

应用超大规模天线阵列(Extremely Large-scale Antenna Array, ELAA)是未来6G移动通信基站的发展趋势。ELAA的孔径增加使阵列近场区域扩大,原有研究中的远场假设不再成立,对于ELAA近场通信,应该建立正确的近场模型进行研究。基于此,建立了近场球面波信号模型并提出了ELAA近场多用户多输入多输出(Multiple-Input Multiple-Output, MIMO)通信系统模型,通过进行波束赋形设计优化近场通信的可达和速率。为了突出正确近场通信模型的重要性,对比了原有远场平面波假设下的波束赋形设计在近场通信中的性能。此外,考虑到ELAA的硬件开销,设计了相位提取-迫零(Phase Extraction Zero-Forcing, PE-ZF)混合波束赋形方法。结果表明基于近场正确建模的波束赋形设计拥有最佳的和速率,同时提出的PE-ZF混合波束赋形方法拥有良好的性能,验证了ELAA近场通信波束赋形设计的重要性。

The application of Extremely Large-scale Antenna Array(ELAA)is the future trend of the 6G mobile base station.Increase in aperture of the ELAA has expanded the near-field area and the far-field assumption in original study no longer exists,so that a correct near-field model should be developed for the study of near-field communications with ELAA.Based on this,we established a near-field spherical wave signal model and proposed a model for near-field Multiple-Input Multiple-Output(MIMO)communication system with ELAA in this paper,optimizing the reachability and rate of near-field communications by performing beamforming design.To highlight the importance of the correct near-field communications model,the performance of the beamforming design in near-field communications under original far-field plane wave assumption is compared.In addition,considering the hardware overhead of ELAA system,a Phase Extraction Zero-Forcing(PE-ZF)hybrid beamforming method is designed.Results show that the beamforming design based on the correct modeling of the near field has the best sum rate,which verifies the importance of beamforming design for ELAA near-field communications,while the proposed PE-ZF hybrid beam assignment method has good performance.