近场信道建模与分析

Near Field Channel Modeling and Analysis

超大规模天线阵列在近期取得了快速发展并有望在未来无线通信,尤其是在中频和毫米波频段取得广泛应用。随着天线孔径的提升,近场效应变得更为明显和突出,因此传统远场平面波假设不再适用。为更准确地对近场通信进行性能评估,建立准确反映近场信道特性的信道模型尤为关键,基于电磁理论和物理光学,建立了一般散射体的散射模型。通过对近场散射体散射特性的研究,分析了非视距(Non-Line of Sight,NLoS)径信道状态的变化特点以及近场场景中的空间非平稳(Spatial Non-Stationary,SNS)特征。基于大规模收发天线阵元间空间一致性特性,结合散射体散射特性,设计了基于空间一致性的近场信道参数生成方法,并提出一种衰减因子计算方法,用以表征空间非平稳特性。在3GPP标准信道建模流程基础上,设计了一种适用于近场电磁波传播的信道模型。提出的信道模型同时建模了球面波和空间非平稳特性对近场通信的影响,可准确评估近场通信性能,为近场码本设计、波束成型等技术的发展打下基础。

The evolution of the extremely large-scale antenna arrays has been achieved so far which is expected to be deployed in future wireless network,e.g.,in the middle frequency band and millimeter wave frequency band.Traditional far-field plane wave-front assumption will not applicable since the impact of near-field effect becomes more obvious and prominent along with the increased aperture size of antenna.To ensure the accuracy for performance evaluation of near-field communications,it is particularly important to establish a channel model that reflects the characteristics of near-field channel.This paper first establishes a scattering model for general scatterers based on electromagnetic theory and physical optics.By studying the scattering characteristics of near-field scatterers,the variation characteristics of the Non-Line of Sight(NLoS)path channel and the Spatial Non-Stationary(SNS)characteristics in near-field region are analyzed.Then a near-field channel parameter generation method is designed based on the spatial consistency among the elements in large antenna array and the scattering characteristics of scatterers.And an attenuation factor calculation approach is proposed to characterize the spatial non-stationary characteristics.Finally,a channel model suitable for near-field electromagnetic wave propagation is propose based on the 3GPP standard channel modeling procedure.The channel model introduced in this paper simultaneously captures the impacts of spherical waves and spatial non-stationarity on near-field communication.This channel model can accurately evaluate near-field communication performance and establishes a foundation for the development of near-field codebooks,beamforming,and other related technologies.