Systems and Control Group

This papcr considers the problcm of estimating the time delays alnd doppler shifts of a known wavcform received via several distirict paths by an array of antennas. The general maximum likelihood estimator is presented, and is shown to require a 2d-dimensiorial non-linear minimization, where d is the number of received signal reflections. Two alternative solutions based on signal and noise subspace fitting are proposed, requiring only a d-dimensional min-imization. In particular, we show how to decouple the required search into a two-step procedure, where the delays are estimated and the dopplers solved for explicitly. Initial conditions for the time delay search can be obtained by applying generalizations of the MUSIC and ESPRIT algorithms. 1