A radio transmitter circuit (10) for transmitting signals within an uplink or sidelink frequency band of a cellular communications system is disclosed. It comprises a signal-generation circuit (20) configured to generate a transmission signal to be transmitted, and a radio front-end circuit (30), connected to the signal-generation circuit (20) at an input of the radio front-end circuit (30), for receiving the transmission signal, and configured to be connected to an antenna (40) at an output of the radio front-end circuit and to transmit the transmission signal to a remote node via said antenna (40). The signal-generation circuit (20) is configured to select a distortion function (D1, D2) based on a location of an allocated radio frequency resource, within said uplink or sidelink frequency band, for the transmission signal. Furthermore, the signal-generation circuit (20) is configured to generate an intermediate transmission signal, based on information to be transmitted in the transmission signal. Moreover, the signal-generation circuit (20) is configured to generate the transmission signal by applying the distortion function (D1, D2) to the intermediate transmission signal.