A low-cost and robust maximum likelihood doppler spread estimator

This paper addresses the problem of Doppler spread estimation in Rayleigh flat fading channels using a new low-cost and robust maximum likelihood (ML) technique. Relying on a an elegant approximation of the channel covariance matrix by a two-ray model, we are able to invert the overall approximate covariance matrix analytically thereby obtaining a low-cost closed-form approximation of the likelihood function. We show by computer simulations that the new estimator is accurate over a wide Doppler spread range and that it outperforms many state-of-the-art techniques. In contrast to the latter, it exhibits an unprecedented robustness to the Doppler spectrum shape of the channel since it does not require its a priori knowledge.