Dual-Use of OTFS Architecture for Pulse Doppler Radar Processing

Orthogonal time frequency space (OTFS) modulation is a recently proposed modulation scheme that places the information symbols to be transmitted over the wireless channel in the delay-Doppler (DD) domain. In this paper, we argue that the OTFS discrete DD domain has a natural connection to the range-Doppler matrix encountered in radar signal processing. We show that we can transmit an arbitrary desired pulsed radar signal using an OTFS transmitter if the DD domain symbols at the input of the OTFS transmitter are given by the discrete Zak transform (DZT) of the desired signal. Furthermore, we show that the OTFS receiver processing is identical to that of a basic pulse Doppler radar receiver. Thus, we propose a framework to achieve pulse Doppler radar processing using an existing OTFS communications architecture, where the demodulated OTFS DD frame represents the range-Doppler matrix corresponding to the scattering environment. This dual-use of OTFS has an advantage in the shared spectrum context. We demonstrate this OTFS-based radar system with the help of a simulated example to detect the range and velocity of moving targets in a scattering environment.