Frequency-Varying Doppler Shift Effect on Wideband Orthogonal Time-Frequency Space Systems

In wideband communication systems, the Doppler shift of radio signal should be modeled as a frequency-varying quantity, not a constant. Accordingly, we studied the effect of frequency-varying Doppler shift (FV-DS) on wideband orthogonal time-frequency space (OTFS) systems. From analysis, it is shown that the FV-DS generates the bandwidth proportional interferences across a delay domain. Furthermore, the simulation results verified that the bit-error-rate performance of the wideband OTFS systems is degraded due to the FV-DS-induced interferences. Based on this study, it is concluded that an additional signal processing is necessary to resolve the performance degradation due to the FV-DS-induced interferences when the OTFS is applied to the wideband systems.