Electromagnetic information theory (EIT) is one of the important topics for 6G communication due to its potential to reveal the performance limit of wireless communication systems. For EIT, the research foundation is reasonable and accurate channel modeling. Existing channel modeling works for EIT in non-line-of-sight (NLoS) scenario focus on far-field modeling, which can not accurately capture the characteristics of the channel in near-field. In this paper, we propose the near-field channel model for EIT based on electromagnetic scattering theory. We model the channel by using non-stationary Gaussian random fields and derive the analytical expression of the correlation function of the fields. Furthermore, we analyze the characteristics of the proposed channel model, e.g., the sparsity of the model in wavenumber domain. Based on the sparsity of the model, we design a channel estimation scheme for near-field scenario. Numerical analysis verifies the correctness of the proposed scheme and shows that it can outperform existing schemes like least square (LS) and orthogonal matching pursuit (OMP).

翻译：电磁信息理论（EIT）因其揭示无线通信系统性能极限的潜力，成为6G通信的重要研究课题之一。对EIT而言，研究基础在于合理且准确的信道建模。现有针对非视距（NLoS）场景的EIT信道建模工作主要聚焦远场建模，无法准确捕获近场信道特性。本文基于电磁散射理论，提出了面向EIT的近场信道模型。我们利用非平稳高斯随机场对信道进行建模，并推导了场相关函数的解析表达式。进一步分析了所提信道模型的特性，例如波数域的稀疏性。基于该稀疏特性，我们设计了一种适用于近场场景的信道估计方案。数值分析验证了所提方案的正确性，并表明其性能优于现有方案，如最小二乘（LS）和正交匹配追踪（OMP）。