IMPACT OF DIGITAL PREDISTORTION ON OFDM SYSTEM

Abstract

In this work, theieffectsiofiainonlineariPoweriAmplifieri(PA) ion an Orthogonal FrequencyiDivision Multiplexing (OFDM) systems are investigated and compared with the theoretical framework. Because of the presence of, a high-power amplifier (HPA) atithe transmitter, wireless communication systems are inherently nonlinear. Nonlinearity has a greater impact on waveforms with a highipeak-to-average-power ratio, suchias orthogonal frequencyidivision multiplexingi(OFDM). A digitalipredistorter (DPD) is commonly usedito reduce theinonlinear distortionsicaused by HPAs. It hasibeen demonstrated that theireceived signal via the cascadediDPD+PA architecture contains both residualinoise and aimultiplicativeifactor. Theiresidualinoise is determined byithe DPD's nonlinearityiorder, whereas theimultiplicativeifactor is determined by the PA and DPD's gain. The Bit error rate as system performance and Normalized mean square error as transmitter performance is reported for various prametric models of solid state power amplifiers (SSPA) as well as Travelling Wave Tube Amplifiers (TWTAs).