A calibration method for a base station removes distortion in traffic signals incurred in transmit paths of the base station. The transmit paths are coupled to an antenna array for transmitting the traffic signals in a wireless network. The method includes conditioning a traffic signal to reduce a correlation with another traffic signal before the traffic signals enter the transmit paths. For each of the traffic signals, an impairment estimation is performed based on the traffic signals captured before entering the transmit paths and the traffic signals captured before entering the antenna array. An approximate inverse of the impairment estimation is applied to each of the traffic signals before the traffic signals enter the transmit paths.