A radio system for relaying packetized radio signals, the radio system comprising: - at least one transmit path (70-1, 70-2,..., 70-N) adapted to forward a packetized payload signal as a transmit signal (75-1, 75-2,..., 75-N), - a single synchronisation unit for extracting a temporal order of the packetized payload signal and providing a clocking signal from the packetized payload signal, - a base band calibration signal generator synchronised by the clocking signal and adapted to insert a base band calibration signal into the packetized payload signal, so that the base band calibration signal is synchronised to the packetized payload signal, - a calibration signal modulator adapted to provide a calibration signal responsive to receiving the base band calibration signal, wherein the calibration signal is adapted for calibrating the feedback path, - a digital predistortion unit adapted to apply a digital predistortion (310-1, 310-2,..., 310-N) to the packetized payload signal for linearising a transfer characteristic of the radio system, - a calibration unit adapted to apply phase and amplitude changes to the at least one transmit path (70-1, 70-2,..., 70-N), - a feedback path for feeding back a feedback signal commonly used by the digital predistortion unit and the calibration unit, wherein at least one of the phase and amplitude changes (210-1, 210-2,..., 210-N) and the digital predistortion (310-1, 310-2,..., 310-N) is adapted using the feedback signal, wherein the digital predistortion unit updates the digital predistortion in response to the feedback signal, and wherein the payload signal is correlated with the feedback signal for updating the at least one of the phase and amplitude changes or the digital predistortion, - wherein the calibration signal is forwarded as the feedback signal, and wherein the calibration signal comprises a portion pertaining to the calibration of the phase and amplitude changes, said portion being provided with at least one of a frequency outside a frequency band used in connection with the digital predistortion or in the form of a narrow band signal of vanishing mean value. - at least one transmit path (70-1, 70-2,..., 70-N) adapted to forward a packetized payload signal as a transmit signal (75-1, 75-2,..., 75-N), - a single synchronisation unit for extracting a temporal order of the packetized payload signal and providing a clocking signal from the packetized payload signal, - a base band calibration signal generator synchronised by the clocking signal and adapted to insert a base band calibration signal into the packetized payload signal, so that the base band calibration signal is synchronised to the packetized payload signal, - a calibration signal modulator adapted to provide a calibration signal responsive to receiving the base band calibration signal, wherein the calibration signal is adapted for calibrating the feedback path, - a digital predistortion unit adapted to apply a digital predistortion (310-1, 310-2,..., 310-N) to the packetized payload signal for linearising a transfer characteristic of the radio system, - a calibration unit adapted to apply phase and amplitude changes to the at least one transmit path (70-1, 70-2,..., 70-N), - a feedback path for feeding back a feedback signal commonly used by the digital predistortion unit and the calibration unit, wherein at least one of the phase and amplitude changes (210-1, 210-2,..., 210-N) and the digital predistortion (310-1, 310-2,..., 310-N) is adapted using the feedback signal, wherein the digital predistortion unit updates the digital predistortion in response to the feedback signal, and wherein the payload signal is correlated with the feedback signal for updating the at least one of the phase and amplitude changes or the digital predistortion, - wherein the calibration signal is forwarded as the feedback signal, and wherein the calibration signal comprises a portion pertaining to the calibration of the phase and amplitude changes, said portion being provided with at least one of a frequency outside a frequency band used in connection with the digital predistortion or in the form of a narrow band signal of vanishing mean value.