Wavenumber-Division Multiplexing in Holographic MIMO with NLoS Channels

TL;DR

This paper extends wavenumber-division multiplexing (WDM) to NLoS holographic MIMO channels, providing theoretical analysis and numerical evaluation of capacity and degrees of freedom in complex scattering environments.

Contribution

It introduces a novel application of WDM to NLoS channels, deriving the angular-domain representation and closed-form models for isotropic scattering.

Findings

WDM applied to NLoS channels yields an angular-domain representation.

Closed-form characterization for isotropic scattering matches Jakes' model.

Numerical results show capacity and degrees of freedom depend on scattering conditions.

Abstract

Wavenumber-division multiplexing (WDM) was introduced as a counterpart of orthogonal frequency-division multiplexing in the spatial-frequency domain for line-of-sight holographic multiple-input multiple-output (MIMO) systems. In this paper, we extend WDM to holographic MIMO channels with non-line-of-sight (NLoS) propagation. We show that applying WDM to the NLoS channel yields the corresponding angular-domain representation, which we characterize through the power spectral factor and power spectral density. We further obtain a closed-form characterization for the case of isotropic scattering, recovering Jakes' isotropic model. The analysis is complemented by numerical results evaluating the degrees of freedom and ergodic capacity under both isotropic and non-isotropic scattering.