Pulse Shaping in High Mobility Zak-OTFS Radar Sensing

High-mobility radar environments present significant challenges for traditional radar systems due to large Doppler shifts. This paper explores the use of Zak based Orthogonal Time Frequency Space (OTFS) modulation as a solution for robust radar sensing under high-velocity conditions. By using the delay-Doppler (DD) domain for transmission, OTFS enables improved resistance to time-frequency dispersion. The Zak transform inherently connects the DD domain and the time domain. We focus on two high velocity impairments, the first being the Fractional Doppler Interference (FDI), which appears due to fractional Doppler shifts, and the second being the Doppler Squint Effect (DSE), which appears due to frequency dependent Doppler shifts. To reduce these effects, we perform pulse shaping in DD domain, where we use pulses with small sidelobes. To obtain such pulses we investigate two kinds of DD domain filters, the Root Raised Cosine filter and the Gaussian filter, which we implement as a twisted convolution in the DD domain. Simulation results demonstrate the superior resilience of the filtered Zak-OTFS to FDI and DSE.