MI-ISAC: Magneto-Inductive Integrated Sensing and Communication in the Reactive Near-Field for RF-Denied Environments

TL;DR

This paper introduces MI-ISAC, a magneto-inductive approach for integrated sensing and communication in RF-denied environments, achieving high accuracy and robustness by exploiting reactive near-field coupling.

Contribution

The paper presents a novel magneto-inductive ISAC paradigm that leverages reactive near-field coupling for effective sensing and communication in RF-denied environments, with foundational theoretical and practical results.

Findings

Tri-axial coils enable joint range-and-angle estimation.

Coupling strength varies sharply with range, allowing sub-millimeter accuracy.

Coupling gradient provides high-resolution sensing despite narrow bandwidth.

Abstract

Radio-frequency integrated sensing and communication (RF-ISAC) is ineffective inunderground, underwater, and in-body environments where conductive media attenuate electromagnetic waves by tens of dB per meter. This article presents magneto-inductive ISAC (MI-ISAC), a paradigm that exploits the reactive near-field quasi-static coupling inherent to MI links, enabling a fundamentally different approach to ISAC in these RF-denied environments. Five foundational results are established: (i)~tri-axial coils are necessary and sufficient for identifiable joint range-and-angle estimation; (ii)~coupling strength changes sharply with range, enabling theoretical sub-millimeter accuracy at typical MI distances despite kHz-level bandwidth; (iii)~time-of-flight is ineffective under such narrow bandwidth, but the coupling gradient provides approximately six orders of magnitude finer resolution; (iv)~MI-ISAC can provide 4--10+\,dB sensing gain over time-division baselines; and (v)~the MI-MIMO channel is geometry-invariant and well-conditioned across all orientations. Applications and a research roadmap are discussed.