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arXiv · 2607.17001

Off-grid Variational Bayesian Parameter Estimation for Fractional Delay-Doppler OTFS-ISAC

Van-Chung Luu·Duy H. N. Nguyen
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Abstract

This letter proposes an off-grid variational Bayesian (OVB) method for fractional delay-Doppler (DD) estimation in OTFS-based integrated sensing and communication (ISAC) systems. To enable off-grid parameter estimation, the OTFS channel is reformulated using separable delay and Doppler steering vectors, and the corresponding phase variables are modeled by von Mises distributions. Closed-form variational updates provide posterior statistics for identifying significant paths and pruning redundant candidates, enabling automatic path-number estimation. Simulation results demonstrate that the proposed method achieves higher channel and parameter estimation accuracy than conventional fractional DD estimation approaches.

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Van-Chung Luu, Duy H. N. Nguyen. 2026-07-18. Off-grid Variational Bayesian Parameter Estimation for Fractional Delay-Doppler OTFS-ISAC. https://arxiv.org/abs/2607.17001

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