Timing synchronization based on Radon–Wigner transform of chirp signals for OTFS systems

Abstract

Accurate timing synchronization is fundamental for the orthogonal time frequency space (OTFS) system to work properly, but the severe Doppler effect makes it a challenging task in high-mobility environments and high carrier frequency systems. To tackle this challenge, we propose a timing synchronization algorithm based on the Radon-Wigner transform (RWT) of chirp signals for OTFS modulation systems in high-mobility environments, which makes full use of the anti-Doppler performance of chirp signals and the energy aggregation characteristics of RWT to achieve accurate timing synchronization in high-Doppler conditions. Firstly, a training sequence consisting of a dual-chirp signal is transformed from the time domain to the delay-Doppler domain and then superimposed on the user data at the transmitter side. Subsequently, the timing synchronization of the OTFS system is implemented by detecting the peak value of the chirp signal after RWT and computing the difference in peak position between the transmitted and received chirp signals. Simulation results demonstrate that the proposed scheme offers a superior performance gain in low signal-to-noise ratio and high-Doppler conditions.