ACCOR: Attention-Enhanced Complex-Valued Contrastive Learning for Occluded Object Classification Using mmWave Radar IQ Signals

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Abstract:Millimeter-wave (mmWave) radar provides robust sensing under adverse conditions and can penetrate thin materials for non-visual perception in industrial and robotic settings. Recent work with MIMO mmWave radar has demonstrated its ability to penetrate cardboard packaging for occluded object classification. However, existing models leave room for improvement and extensions across different sensing frequencies. Building on recent work with MIMO radar for occluded object classification, we propose ACCOR, an attention-enhanced complex-valued contrastive learning approach for radar, enabling robust occluded object classification. ACCOR processes complex-valued IQ radar signals via a complex-valued CNN backbone, a multi-head attention layer and a hybrid loss. The hybrid loss combines a weighted cross-entropy term with a supervised contrastive term. We extend an existing 64 GHz dataset with a new 67 GHz subset and evaluate performance across both bands. ACCOR achieves 96.60 % accuracy at 64 GHz and 93.59 % at 67 GHz on 10 objects, surpassing prior radar-specific and adapted image models. Results demonstrate the benefits of integrating complex-valued deep learning, attention, and contrastive learning for mmWave radar-based occluded object classification.

Comments: 9 pages, 8 figures

Subjects:

Signal Processing (eess.SP)

Cite as: arXiv:2512.11556 [eess.SP]

(or arXiv:2512.11556v4 [eess.SP] for this version)

https://doi.org/10.48550/arXiv.2512.11556

arXiv-issued DOI via DataCite

Submission history

From: Stefan Hägele [view email] [v1] Fri, 12 Dec 2025 13:38:59 UTC (1,650 KB) [v2] Thu, 5 Mar 2026 13:28:30 UTC (1,980 KB) [v3] Fri, 6 Mar 2026 13:43:52 UTC (1,979 KB) [v4] Thu, 2 Apr 2026 08:19:11 UTC (2,195 KB)