High Power Amplifier Linearization Using Zernike Polynomials in a LTE Transmission
Digital Pre-Distortion (DPD) is a highly cost-effective technique to linearize High Power Amplifiers (HPAs) in wireless applications. The polynomial-type behavioral models are widely used both for HPAs and pre-distorters, but they often suffer from the numerical instability when high order nonlinearities are included. In this paper, the authors propose a new polynomial pre-distorter model considering the use of a orthogonal polynomial model based on a Zernike polynomial basis which is very robust and stable when classical identification techniques are applied. Computer simulations in a LTE uplink transmission confirm the pre-distorter computed with the Zernike polynomial model provides improvements in Adjacent Channel Leakage Ratio (ACLR) with stability and moderate complexity in the DPD coefficient estimation.