Estimation of time-varying multipath channel parameters using chirp signals

We propose a method for estimating the parameters of linear time-varying multipath channels, based on the transmission of consecutive chirp signals having different sweep rates. We show that the channel parameter estimation problem can then be recast as a harmonics-in-noise problem. We estimate the number of paths and the parameters of each path, and then we use our estimates to predict the future channel evolution. We compute the variance of the proposed estimator, and show that performance is close to the Cramer-Rao bound, at least as far as the estimates of the Doppler frequency shifts are concerned.