Wideband Near-field Extension for the 3GPP Geometry Based Stochastic Channel Model

This technical report presents a preliminary investigation into near-field propagation effects in wireless communication channels, extending the conventional 3GPP geometry-based stochastic channel model to account for spherical wavefront characteristics. Traditional radio channel models primarily assume far-field conditions, where the plane wave approximation is valid. However, as antenna arrays grow in electrical size, communication distances shorten, and higher frequency bands with wider bandwidths are deployed, near-field modeling becomes increasingly critical. This report introduces modifications to the existing 3GPP framework, incorporating near-field effects in both line-of-sight (LoS) and non-line-of-sight (NLoS) paths. A novel virtual image theory is proposed to determine specular reflection distances, while stochastic modeling techniques are applied to characterize scattered multipaths. The framework ensures consistency with existing channel models while improving accuracy in the Fresnel region. As this is an ongoing study, this document serves as an initial version and will be continuously updated with new findings, refinements, theoretical, and experimental validations. Acknowledgement: This work is funded by the Hexa-X-II project, receiving funding from the Smart Networks and Services Joint Undertaking (SNS JU) under the European Union’s Horizon Europe research and innovation programme under Grant Agreement No. 101095759.