Digital Predistortion for Wireless Transmitters in 5G: System Requirements and Design Challenges

In existing cellular base stations, to guarantee linearity, digital predistortion (DPD) is widely used to compensate for the nonlinear distortion generated by RF power amplifiers (PAs). In 5G, particularly in high frequency and wideband millimeter wave transmitters, the conventional DPD is no longer workable because high sampling rates are required that leads to high power dissipation and cost. Simply going back to analog predistortion seems not a solution since analog circuit is difficult to calibrate and it is not scalable. In this talk, we will discuss the future trends of 5G wireless transmitters and related modeling and system design challenges that we are facing in developing DPD techniques for such systems. Particular emphasis will be given to DPD model selection, feedback loop data acquisition, model extraction algorithms and various system architectures. Hardware and software system implementation issues will also be discussed.