SAR/ISAR Imaging in 6G Network

2026-04-01

AI Summary

This work addresses the challenge of achieving high-resolution radar imaging in 6G integrated sensing and communication systems, which typically operate with only MHz-level bandwidth—far below the GHz–THz bandwidths required by conventional radio-frequency imaging techniques for precise range estimation. To overcome this limitation, the paper introduces two novel paradigms: bandwidth-independent synthetic aperture radar (BI-SAR) and inverse synthetic aperture radar (BI-ISAR). These approaches enable high-resolution imaging solely through Doppler information, eliminating reliance on range-domain data by leveraging either a moving base station observing a static target or a static base station observing a rotating target. The proposed framework breaks from traditional SAR/ISAR assumptions by realizing, for the first time, purely Doppler-driven, bandwidth-agnostic imaging. An iterative adaptive Doppler association (IAA-DA) algorithm, combined with 360° observation geometry, effectively resolves coherence degradation caused by directional scattering. Real-world experiments validate the feasibility and efficacy of high-resolution radar imaging under MHz-level bandwidth constraints.

Abstract

Imaging is a crucial sensing function that finds wide applications in environmental reconstruction, autonomous driving, etc. However, the signal processing methods for existing radio imaging techniques, such as millimeter wave (mmWave) imaging, require high-resolution range estimation enabled by Gigahertz-level or even Terahertz-level bandwidth, and cannot be applied in 6G integrated sensing and communication (ISAC) network with Megahertz-level bandwidth. This paper proposes two novel high-resolution radio imaging schemes that can work on the 6G signals with limited bandwidth - bandwidth-independent synthetic aperture radar (BI-SAR), where the movable base station (BS) revolves along the static targets by 360 degrees; as well as bandwidth-independent inverse synthetic aperture radar (BI-ISAR), where the BS is static and the targets revolve along an axis by 360 degrees. Different from conventional SAR and ISAR counterparts that rely on range estimation, our proposed imaging schemes solely utilize Doppler information to perform imaging without any range information. The main technical challenge of our schemes lies in the anisotropic scattering functions over different directions, which hinder the coherent synthesis of the backscattered signals from all directions. We design an iterative adaptive approach-based Doppler association (IAA-DA) algorithm to tackle the above issue. Moreover, we also derive the imaging resolution to characterize the reconstruction quality. Real-world experiments are provided to show the feasibility and the effectiveness of our proposed 6G imaging schemes.

Problem

• SAR/ISAR imaging
• 6G ISAC
• limited bandwidth
• high-resolution imaging
• Doppler-based imaging

Innovation

• Bandwidth-Independent SAR
• Doppler-only Imaging
• 6G ISAC
• IAA-DA Algorithm
• Anisotropic Scattering