This paper proposes a novel pilot-aided algorithm for estimation of rapidly varying wireless channels in OFDM systems.This approach is specifically designed for channels varying on the scale of a single OFDM symbol duration. From the pilot information,we recover information about the channel taps in the framework of the Basis Expansion Model (BEM). In this paper explicit formulas forthe BEM coefficients in terms of the receive signal are derived. For a system with L channels taps, our method uses (Llog L) operationsand
(L) memory per OFDM symbol.