Theoretical Investigation of Digital Predistortion System

Some doubt has been cast upon the predistortion system applying indirect learning structure (IDLS). In this paper, using the polynomial model for the predistorter (PD), theoretical investigation and simulation on the predistortion system performance basing on IDLS is put out. The result shows that the performance of IDLS predistortion system is affected by PD modeling error and the measurement noise, and the upper bound of the system normalized nean square error (NMSE) caused by the measurement noise is just the noise to signal ration, and if the measurement noise is low enough, there is a NMSE floor caused by modeling error. This is a novel result which can help to make predict approximate estimation of the factual IDLS predistortion system performance.