A radio communications method, includes carrying out, by a transmitter: generating or receiving digital symbols to be transmitted; generating, every S digital symbols generated/received (with S integer higher than three), a corresponding multi-mode digital signal; generating a multi-frame digital signal comprising successive, non-overlapped time frames, each of which has the predefined time length and carries a respective multi-mode digital signal generated; and transmitting a radio frequency signal carrying the multi-frame digital signal. The radio communications method further includes carrying out, by a receiver: receiving the radio frequency signal transmitted by the transmitter; processing the received radio frequency signal to obtain a corresponding incoming digital signal; performing, on the basis of the incoming digital signal, carrier synchronization, clock synchronization, and frame synchronization; and extracting, on the basis of the carrier, clock and frame synchronizations.