Super-Resolution Sensing of User Equipment Using Delay-Doppler Pilot-Data Structure in RIS-Aided OTFS Systems

In this paper, we propose a delay-Doppler (DD) domain pilot-data structure for OTFS systems and model the channel estimation (CE) problem as a sparse recovery problem in the time domain (TD). The pilots and data are arranged in the DD frame in such a way that they can be well separated in the TD. We then consider a reconfigurable intelligent surface (RIS) assisted OTFS system and use the proposed DD domain frame structure sent by the user to sense its range-velocity parameters leveraging the orthogonal matching pursuit (OMP) with fractional refinement algorithm. Simulation results show the superior performance of the proposed CE framework in OTFS systems over the traditional embedded pilot (EP) aided scheme in terms of normalized channel mean square error and validate the feasibility of the pilot-data structure-aided sensing scheme in RIS assisted OTFS systems.