Blind Wide-Range Carrier Frequency Offset Estimation for CP-OTFS System

Orthogonal Time-Frequency Space (OTFS) modulation has been popularized for its impressive advantages in mobile communication scenario. However, carrier frequency offset (CFO) caused by high-speed motion and transceiver frequency inconsistency can lead to inter-carrier interference. Furthermore, CFO may exceed the subcarrier spacing in some scenarios, such as satellite communication. Existing methods designed for OTFS mainly focus on fractional CFO, ignoring the integer CFO estimation task. In this letter, a blind wide-range CFO estimation method is proposed for cyclic prefix OTFS system to solve the problem of narrow CFO estimation range. Based on the cyclic prefix in the Delay-Doppler domain, a cost function is constructed to minimize the difference between cyclic prefix and its replicated part. Further, a two-stage estimation method is designed by computing the above cost function and existing fractional CFO estimator using multi-frame data to accomplish rough and precise estimation. The simulation results show that the proposed two-stage estimation method has a wider range and better accuracy compared to the previous CFO estimator.