Basis expansion ideas are used for blind equalization of rapidly fading time-varying channels. Each time-varying coefficient is expanded onto a basis and the expansion parameters are estimated. It is shown that the mobile radio channel falls into this framework and its time-variation is well described by an exponential basis. Linear and nonlinear algorithms are derived to estimate the expansion parameters using time-varying cumulants. Identifiability and consistency are also established. Finally, a procedure for estimating the frequencies of the exponentials is delineated.<<ETX>>