Wavenumber-domain signal processing for holographic MIMO: Foundations, methods, and future directions

TL;DR

This paper introduces a wavenumber-domain signal processing framework for holographic MIMO systems, addressing the limitations of traditional methods in near-field and subwavelength regimes, and discusses future research directions.

Contribution

It provides a comprehensive overview of wavenumber-domain techniques for H-MIMO, including channel modeling, multiplexing, and waveform design, highlighting their advantages over classical approaches.

Findings

Wavenumber domain effectively models near-field H-MIMO channels.

Wavenumber-based methods improve channel estimation accuracy.

The framework supports advanced multiplexing and waveform design for next-gen systems.

Abstract

Holographic multiple-input multiple-output (H-MIMO) systems represent a paradigm shift in wireless communications by enabling quasi-continuous apertures. Unlike conventional MIMO systems, H-MIMO with subwavelength antenna spacing operates in both far-field and near-field regimes, where classical discrete Fourier transform (DFT) representations fail to sufficiently capture the channel characteristics. To address this challenge, this article provides an overview of the emerging wavenumber-domain signal processing framework. Specifically, by leveraging spatial Fourier plane-wave decomposition to model H-MIMO channels, the wavenumber domain offers a unified and physically consistent basis for characterizing subwavelength-level spatial correlation and spherical wave propagation. This article first introduces the concept of H-MIMO and the wavenumber representation of H-MIMO channels. Next, it elaborates on wavenumber-domain signal processing technologies reported in the literature, including multiplexing, channel estimation, and waveform designs. Finally, it highlights open challenges and outlines future research directions in wavenumber-domain signal processing for next-generation wireless systems.