A coherent or a noncoherent transmission mode is automatically selected for a transmission on the basis of an estimated Doppler frequency shift due to a motion of a mobile terminal. A coherent mode is selected if a pilot signal overhead is not excessive to uniquely characterize a Doppler frequency shift, as at lower carrier frequency times relative velocity products. A noncoherent mode is selected if a pilot signal overhead would be excessive to uniquely characterize a Doppler frequency shift at higher carrier frequency times relative velocity products. Both the coherent and noncoherent modes have respective advantages for their respective carrier frequency time relative velocity regimes.