A Robust Frequency MMSE Estimator Based on the Weighted Average of Multipath Signal for OTFS Systems

A robust frequency minimum mean square error (MMSE) estimator based on the weighted average of multipath signal for OTFS systems is proposed in this paper. Previous frequency estimators are based on the strongest single path signal or equally weighted average of multiple path signals so that the accuracies of estimators are limited. We generalise the weight coefficients to be taken arbitrarily, and their optimal values are determined such that the MSE of estimator is minimum. Simulation results show that the proposed method outperforms existing frequency estimators in terms of MSE performance, particularly when the normalized carrier frequency offset (CFO) is less than 0.5 and the symbol signal-to-noise ratio (SNR) of received signal is below 2 dB. Under static channel conditions, the proposed estimator can achieve a reduction in pilot energy of approximately 21.6 dB.