Cramer-Rao lower bounds of joint delay-Doppler estimation for an extended target

The Cramer-Rao Lower Bounds (CRLBs) of the joint time delay and Doppler stretch estimation for an extended target is derived in this paper. The results indicate that the CRLB of the Doppler stretch is inversely proportional to the effective time-bandwidth product of the transmitted signal. The estimator using wideband ambiguity function (WBAF) is evaluated for the extended target case through numerical experiments. Our results indicate that the WBAF estimator, which is derived under the single point scatterer assumption, is not appropriate to the parameter estimation for an extended target.