New Digital Predistorter Architecture for Signals with High Peak-to-Average Power Ratios

Two closely related non-linear distortions are introduced to the frontend of a transmitting multicarrier signal: a clipping noise due to a high peak-to-average-power-ratio (PAPR) reduction and intermodulation distortions from the nonlinearity of high power amplifiers (HPAs). In recent years, there has been growing interest in various PAPR reduction and linearization techniques using predistortion schemes. Although these two impairments are somewhat interdependent, most designs deal with them separately as it relates to problem formulation, optimization objectives and implementation issues. The overall performance may not be maximized even if each of them is optimized under their own criteria due to possible conflicts of interest. In this paper, we present a new predistorter architecture that jointly optimizes PAPR reduction and digital predistortion, and achieves better transmitting signal quality for desired levels of PAPR. During the optimization, only the clipping noise was employed, so the proposed predistorter became an independent PAPR-specific reduction scheme, i.e., it is robust, and it can therefore operate with various standard and non-standard PAPR reduction solutions.