Stochastic Green's Function Based Channel Modeling for Holographic MIMO Systems

The emerging technology and transfer from far-field communications to powerful near-field communications bring favorable performance gain, however, the traditional channel modeling fails to accurately depict mutual coupling effects and represent near-field gains. To deal with this issue, this paper first proposes an effective electromagnetic channel model based on stochastic Green's functions to depict a practical multi-path environment for holographic multi-input multiple-output (HMIMO) systems. Specifically, there are numerous electromagnetic waves transmitted and reflected in the multi-path environment, thus the means and variances of these electromagnetic waves can be obtained through the law of large numbers. Subsequently, the stochastic Green's function is established to describe point-to-point transmission, including the polarization effects and spatial correlations. Based on this probabilistic channel model, both near-field and far-field HMIMO communications are modeled. Simulation results (channel correlation, eigenvalue distribution, and capacity) also validate the effectiveness of the proposed channel and substantiate the additional capacity gain for HMIMO systems brought by multi-path effects in far-field region.