Parameter estimation of range-migrating targets using OTFS signals from LEO satellites

Abstract

This study investigates a communication-centric integrated sensing and communication system that utilizes orthogonal time-frequency space (OTFS) modulated signals emitted by low Earth orbit (LEO) satellites to estimate the initial-range, range-rate, and amplitude of point-like targets experiencing range migration under a first-order range model over the OTFS frame. Leveraging the signal samples produced by off-the-shelf OTFS demodulators, we derive the delay-Doppler-domain input-output relationship governing the target echo under both ideal and rectangular shaping filters. The target response exhibits a sparse structure in the delay-Doppler domain, whose support is determined by the target initial-range and range-rate. Exploiting this sparse model, we derive a lower-complexity approximation of the maximum-likelihood estimator for the target parameters. The proposed method first obtains coarse estimates of the target initial-range and range-rate using block orthogonal matching pursuit; then, a bank of matched filters focused on a smaller initial-range/range-rate region refines these two estimates and computes the amplitude estimate. The single-target procedure is extended to multiple targets via iterative estimation, reconstruction, and cancellation of dominant echoes. Finally, numerical examples are provided to evaluate the estimation performance.