（中国科学技术大学，中国 合肥 230026）
Near-Field Communication and Positioning: From Spherical Wavefront Model to Electromagnetic Field Theory
CHEN Ang, CHEN Li, WEI Guo
(University of Science and Technology of China, Hefei 230026, China)
Abstract: The boundary conditions and radiation characteristics of the reactive near-field, radiative near-field, Fresnel, and far-field regions of the electromagnetic diffraction domain are introduced and derived. For communication in the radiative near-field region, the spherical wavefront model is introduced, through which the near-field communication signal can be modeled correctly. For the positioning in the radiative near-field region, the spherical wavefront model is no longer accurate. The electromagnetic field theory is used to model the near-field channel and a general near-field positioning model is proposed, and the Cramér-Rao bound of near-field positioning based on the estimation theory is derived.
Keywords: electromagnetic diffraction domain; near-field communication; near-field positioning; spherical wavefront model; electromagnetic field theory