SNR-independent methods for estimating maximum Doppler frequency

In this letter, we propose two maximum Doppler frequency estimators that are based on the level crossing rate (LCR) and the covariance function (COV). To eliminate the effect of additive noise, we analyze the conditions for the estimators independent of the signal-to-noise ratio (SNR) and implement the conditions with a simple downsampling process. The proposed methods achieve good SNR-independent performance.