Performance analysis of superimposed pilot channel estimation for OTFS in fractional doppler channels

Official URL: https://dx.doi.org/10.1109/SIU71813.2026.11636808

Orthogonal Time Frequency Space (OTFS) modulation is a promising technology for 6G and beyond, as it overcomes severe Doppler shifts in high-mobility environments. However, physical channel paths introduce fractional Doppler shifts that cause inter-Doppler interference. Conventional pilot-based channel estimation mitigates this by transmitting pilots in time-multiplexed frames (block pilots), which degrades spectral efficiency. In this study, a Superimposed Pilot (SP) based channel estimation architecture for OTFS is implemented and evaluated against Block Pilot, Pseudo-Noise sequence, and Ideal Channel State Information methods. By overlaying the pilot directly onto the data across the delay-Doppler grid, the need for dedicated pilot time slots is eliminated. Simulation results under 3GPP Extended Vehicular A conditions at 500 km/h show that the SP scheme achieves higher throughput than the Block Pilot scheme while maintaining comparable reliability at high signal-to-noise ratio.