The present technology relates to a channel estimator configured to operate based on a discrete wave channel model and measured channel responses between a transmitter having at least one transmit antenna and a receiver having at least one receive antenna. The channel estimator comprises a windowed likelihood determiner and a maximization processor. The windowed likelihood determiner is configured to determine a windowed likelihood function based on the measured channel responses, a selected window function, and modeled channel responses defined based on a number of discrete waves according to the discrete wave channel model. The maximization processor is configured to perform maximization of the windowed likelihood function, using initial input in the form of at least one of predetermined wave propagation delay(s) and predetermined wave propagation direction(s) for at least one of the discrete waves, to extract the wave parameters of the discrete waves.