The radio system comprises a radio unit and an antenna unit coupled to the radio unit. The antenna unit is physically separate and located remote from the radio unit. The antenna unit further comprises a digital pre-distortion engine configured to pre-distort a modulated digital data signal; a digital to analog converter configured to convert the pre-distorted digital data signal to a pre-distorted analog data signal; and a power amplifier configured to amplify the pre-distorted analog data signal which distorts the pre-distorted analog data signal. The distortion introduced by the power amplifier is opposite to the pre-distortion introduced by the digital pre-distortion engine such that the pre-distortion introduced by the digital pre-distortion engine approximately cancels the distortion introduced by the power amplifier. The radio unit further comprises a coefficient computation engine configured to calculate coefficients used by the digital pre-distortion engine to pre-distort the modulated digital data signal.