Passive Sensing and Channel Estimation Methods for OTFS-ISAC System

Integrated sensing and communication (ISAC) sys-tems have attracted considerable attention in recent years. This paper proposes an ISAC system based on orthogonal time frequency space (OTFS) modulation, designed to enhance performance in high-mobility environments. We introduce a novel passive sensing method that enables high-resolution target parameter estimation through fine-grained grid search, two-stage parameter refinement. Additionally, we develop a channel estimation method that leverages sensing parameters, utilizing delay-Doppler domain information in OTFS systems to enhance accuracy in high-mobility scenarios. Simulation results across various Signal-to-Noise ratio (SNR) conditions demonstrate the effectiveness of the proposed methods, showing a significant reduction in the root mean square error (RMSE) of distance and velocity estimations as SNR increases. These findings highlight the accuracy of the proposed algorithms in high-noise environments.