A two-ray spectrum-approximation approach to Doppler spread estimation with robustness to the carrier frequency offset

We propose a new simple and accurate approach to estimate the Doppler spread which is a key parameter in the context of wireless communication systems. This new approach stems from the well known fact that the crosscorrelation of the channel is a weighted summation of monochromatic plane waves (or inverse Fourier transform of its power spectral density). In the case of Doppler spread, these plane waves are locally distributed around a main frequency which is nothing but the carrier frequency offset (CFO). This special feature accounts for the Taylor series expansions that we use herein to develop a two-ray spectrum approximate model. The resulting approximation allows us to determine a new simple and accurate closed-form estimator of the Doppler spread under the unique symmetry assumption on the channelpsilas spectrum. Simulations illustrate the advantages of the proposed technique and its robustness to the CFO.