HiSAC: High-Resolution Sensing with Multiband Communication Signals

TL;DR

HiSAC is a novel multiband ISAC system that achieves super-resolved passive ranging by combining diverse, non-contiguous subbands across wide frequency ranges, reusing communication signals and phase coherence techniques.

Contribution

It introduces the first multiband ISAC system that effectively combines sparse subbands for high-resolution sensing, addressing phase incoherence and non-contiguity issues.

Findings

Enhances sensing resolution by up to 20 times.

Operates across different frequencies and technologies.

Validated on millimeter-wave platform with objects and humans.

Abstract

Integrated Sensing And Communication (ISAC ) systems are expected to perform accurate radar sensing while having minimal impact on communication. Ideally, sensing should only reuse communication resources, especially for spectrum which is contended by many applications. However, this poses a great challenge in that communication systems often operate on narrow subbands with low sensing resolution. Combining contiguous subbands has shown significant resolution gain in active localization. However, multiband ISAC remains unexplored due to communication subbands being highly sparse (non-contiguous) and affected by phase offsets that prevent their aggregation (incoherent). To tackle these problems, we design HiSAC, the first multiband ISAC system that combines diverse subbands across a wide frequency range to achieve super-resolved passive ranging. To solve the non-contiguity and incoherence of subbands, HiSAC combines them progressively, exploiting an anchor propagation path between transmitter and receiver in an optimization problem to achieve phase coherence. HiSAC fully reuses pilot signals in communication systems, it applies to different frequencies and can combine diverse technologies, e.g., 5G-NR and WiGig. We implement HiSAC on an experimental platform in the millimeter-wave unlicensed band and test it on objects and humans. Our results show it enhances the sensing resolution by up to 20 times compared to single-band processing while occupying the same spectrum.