Enhancing Channel Estimation in High Mobility OTFS Systems: A Novel Pilot-Based Method Exploiting Doppler Axis Diversity in a TransPod Transportation System

In this paper, we introduce a novel pilot-based channel estimation approach for Orthogonal Time Frequency Space (OTFS) modulation systems. Our proposed method, which involves inserting a row of pilot symbols in the zero padding region of the ZP-OTFS system, offers significant advantages such as reduced overhead and lower Peak-to-Average Power Ratio (PAPR). Notably, by spreading pilot symbols across the Doppler axis, our method provides robust and accurate channel estimation even in high mobility scenarios, a characteristic feature of environments like the TransPod system for 1000 km/h+ transportation. This is crucial, as the Doppler shifts in such scenarios could otherwise lead to substantial degradation in system performance. We investigate the channel transfer function of the TransPod guideway using the ray-tracing propagation model to illustrate this advantage. Through simulation results, we demonstrate that our proposed method outperforms the conventional pilot-based estimation method, highlighting its potential to significantly enhance OTFS system performance in practical, high-mobility scenarios. This research offers valuable insight into the potential improvements in OTFS channel estimation techniques and their real-world applications.