Cramer-Rao bounds and estimators for the parameters of time selective fading channels

We consider the problem of estimating the Doppler shift and rate of a linearly modulated digital signal subject to time selective Rician fading. We derive the Cramer-Rao bounds for the parameters; we propose an estimator, based on the higher-order ambiguity function (HAF), and show that it is consistent. We also establish some interesting results in the context of estimating the parameters of a polynomial phase signal in complex multiplicative noise.