Baseband compensation techniques for bandpass nonlinearities [RF front-ends]

In this paper, we present and compare several methods of compensating the nonlinearity of the RF front-end of a wireless system. Two baseband compensation techniques, namely predistortion and postdistortion (equalization) of the baseband signal are discussed and the problems associated with each one is addressed. Furthermore, a combination of a predistorter and a nonlinear equalizer, and also predistortion of an oversampled baseband signal, are analyzed. It is shown that under realistic conditions, with a frequently saturated amplifier, and ISI channel, the latter two methods are able to compensate for the nonlinearity to a good extent, while the first two methods can only operate under certain assumptions for channel conditions and nonlinearity type.