Joint Optimization of PAR Reduction and Digital Predistortion for Wireless LAN Applications

Two closely related non-linear distortions introduced in a multicarrier modulation based wireless local area network (LAN) transmitter are clipping due to high peakto-average-power-ratio (PAR) and saturation due to nonlinear power amplifiers. Various PAR reduction and RF nonlinearity compensation schemes can be found in literature and implemented in realtime systems to tackle them. Although these two impairments are interdependent to some extent, most designs deal with them separately on problem formulation, optimization objective and implementation issues. Overall performance might not be maximized even if each of them has been optimized under their own criteria due to possible conflicts of interests. In this paper, we present an approach to jointly optimize PAR reduction and baseband RF nonlinearity compensation (so called digital predistortion) to achieve a better performance/complexity tradeoff under certain design limitations of a practical wireless LAN transceiver.