TITLE:
A Discrete Newton's Method for Gain Based Predistorter
AUTHORS:
Xiaochen LIN, Minglu JIN, Aifei LIU
KEYWORDS:
Predistortion, Discrete Newton’s Method, Power Amplifiers (PAs), Lookup Table (LUT)
JOURNAL NAME:
International Journal of Communications, Network and System Sciences,
Vol.1 No.1,
June
4,
2008
ABSTRACT: Gain based predistorter (PD) is a highly effective and simple digital baseband predistorter which compensates for the nonlinear distortion of PAs. Lookup table (LUT) is the core of the gain based PD. This paper presents a discrete Newton’s method based adaptive technique to modify LUT. We simplify and convert the hardship of adaptive updating
LUT to the roots finding problem for a system of two element real equations on athematics. And we deduce discrete Newton’s method based adaptive iterative formula used for updating LUT. The iterative formula of the proposed method is in real number field, but secant method previously published is in complex number field. So the proposed
method reduces the number of real multiplications and is implemented with ease by hardware. Furthermore, computer simulation results verify gain based PD using discrete Newton’s method could rectify nonlinear distortion and improve system performance. Also, the simulation results reveal the proposed method reaches to the stable statement in fewer
iteration times and less runtime than secant method.