1. A method of modelling a power amplifier fed by one of a wideband signal and an intra-band carrier aggregated signal, the method comprising: receiving the one of the wideband signal and the intra-band carrier aggregated signal; generating a discrete base band equivalent, BBE, Volterra series based on the received signal, the series having distortion products grouped according to determined shared kernels, the discrete BBE Volterra series being used to model the power amplifier; the shared kernels being determined based on a transformation of a real-valued continuous-time pass band Volterra series without pruning of kernels; and applying the discrete BBE Volterra series to predistort the one of the wideband signal and the intra-band carrier aggregated signal to achieve a linearization of the power amplifier.