Electromagnetic information theory (EIT) is one of the emerging 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., channel degrees of freedom (DoF). Finally, we design a channel estimation scheme for near-field scenario by integrating the electromagnetic prior information of the proposed model. 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通信的新兴研究方向之一。对于EIT而言，合理且准确的信道建模是其研究基础。现有针对非视距（NLoS）场景的EIT信道建模工作主要集中于远场建模，无法准确刻画近场信道的特性。本文基于电磁散射理论，提出了适用于EIT的近场信道模型。我们采用非平稳高斯随机场对信道进行建模，并推导出场相关函数的解析表达式。此外，我们分析了所提信道模型的特性，例如信道自由度（DoF）。最后，通过融合所提模型的电磁先验信息，我们设计了一种面向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，并表明其性能优于最小二乘（LS）和正交匹配追踪（OMP）等现有方案。