A remote radio unit for a base transceiver station, wherein the remote radio unit comprises: a noise generator configured to provide a radio-frequency, RF, noise signal having predefined statistical properties; a communication interface configured to transmit, to a central unit of the base transceiver station, the RF noise signal, received from the noise generator, as a stimulus signal over a radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station, wherein the communication interface is further configured to receive from the central unit a pre-distorted target signal over a ROF downlink channel between the remote radio unit and the central unit of the base transceiver station; and an antenna for transmitting the pre-distorted target signal received by the communication interface; wherein the remote radio unit further comprises a power splitter configured to split the stimulus signal into a first stimulus signal and a second stimulus signal, wherein the communication interface is configured to transmit the first stimulus signal over the radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station and to transmit the second stimulus signal over a further radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station; wherein the remote radio unit further comprises a first local power control unit configured to control the power of the first stimulus signal to be transmitted over the radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station and a second local power control unit configured to control the power of the second stimulus signal to be transmitted over the further radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station. a noise generator configured to provide a radio-frequency, RF, noise signal having predefined statistical properties; a communication interface configured to transmit, to a central unit of the base transceiver station, the RF noise signal, received from the noise generator, as a stimulus signal over a radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station, wherein the communication interface is further configured to receive from the central unit a pre-distorted target signal over a ROF downlink channel between the remote radio unit and the central unit of the base transceiver station; and an antenna for transmitting the pre-distorted target signal received by the communication interface; wherein the remote radio unit further comprises a power splitter configured to split the stimulus signal into a first stimulus signal and a second stimulus signal, wherein the communication interface is configured to transmit the first stimulus signal over the radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station and to transmit the second stimulus signal over a further radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station; wherein the remote radio unit further comprises a first local power control unit configured to control the power of the first stimulus signal to be transmitted over the radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station and a second local power control unit configured to control the power of the second stimulus signal to be transmitted over the further radio-over-fiber, ROF, uplink channel between the remote radio unit and the central unit of the base transceiver station.