The Doppler spread associated to a transmission channel with a gain represented by a random process, is estimated by transmitting on the channel a digital signal (DPCCHI,Q), which comprises at least one pilot signal, which in turn comprises fields of known symbols, and estimating, on the basis of the pilot signal(DPCCHI,Q), the channel so as to generate a signal indicating the aforesaid gain. There is then detected the zero-crossing rate (η) of the aforesaid signal during a given time interval, and there is also estimated the signal-to-noise ratio (SNR) associated to the channel. The bandwidth ({circumflex over (f)}D) of the aforesaid random process is estimated according to a reference quantity (ID(2)), which comprises: a first term ({circumflex over (η)}2π2), representing an estimate ({circumflex over (η)}) of said zero-crossing rate (η); and a second term ( I N ( 2 ) - η ^ 2 ⁢ π 2 ⁢ I N ( 0 ) 2 ⁢ SNR ) , which includes said signal-to-noise ratio of the channel.