If AFC in the baseband processor CAN detect the doppler frequency shift ( I think AFC cannot distinguish Doppler frequency shift and carrier frequency offset in this case, right?), AFC will adjust the LO to cancel the freq offset. However, considering Jakes U-shape Doppler frequency model, there are two major tone (fc+fd) and (fc-fd) at the front-end of the receiver( Assume that signal bandwidth B>>fd and fc >> fd), LO equals any one will miss the other tone. And it is obvious that is this case the equivalent channel baseband model will occupy bandwith of 2*fd. Is that right?