Near-Field Signal Processing: Unleashing the Power of Proximity

TL;DR

This paper reviews recent advances in near-field signal processing, highlighting new challenges and techniques in applications like wireless communications, holography, and medical imaging, driven by large arrays and wide bandwidths.

Contribution

It provides a comprehensive overview of state-of-the-art near-field signal processing techniques across various applications, emphasizing recent developments and challenges.

Findings

Advances in NF phase retrieval techniques.

Enhanced channel estimation and beamforming methods.

Application of NF localization with acoustic arrays.

Abstract

After nearly a century of specialized applications in optics, remote sensing, and acoustics, the near-field (NF) electromagnetic propagation zone is experiencing a resurgence in research interest. This renewed attention is fueled by the emergence of promising applications in various fields such as wireless communications, holography, medical imaging, and quantum-inspired systems. Signal processing within NF sensing and wireless communications environments entails addressing issues related to extended scatterers, range-dependent beampatterns, spherical wavefronts, mutual coupling effects, and the presence of both reactive and radiative fields. Recent investigations have focused on these aspects in the context of extremely large arrays and wide bandwidths, giving rise to novel challenges in channel estimation, beamforming, beam training, sensing, and localization. While NF optics has a longstanding history, advancements in NF phase retrieval techniques and their applications have lately garnered significant research attention. Similarly, utilizing NF localization with acoustic arrays represents a contemporary extension of established principles in NF acoustic array signal processing. This article aims to provide an overview of state-of-the-art signal processing techniques within the NF domain, offering a comprehensive perspective on recent advances in diverse applications.