Adaptive Simulator of Power Amplifier Nonlinearity Based on Piecewise Polynomial

Abstract

In the wireless communication system, power amplifier nonlinearity has bad effects on transmitting signals and changes channel characteristics. In order to exactly estimate communication system performance, a channel simulator needs to simulate power amplifier nonlinearity. This paper proposes a novel adaptive simulator based on piecewise polynomial. Learning from the digital predistortion technique of power amplifier, the proposed method uses adaptive study structure. It adds a nonlinear preprocessing module before the radio power amplifier of channel simulator, and uses adaptive algorithm to make their cascading characteristics gradually approach to the simulated power amplifier nonlinearity. In order to solve the disadvantages in traditional polynomial and look-up table techniques, the proposed method uses multiple lower-odd-order polynomials to piecewise fit nonlinearity for improving simulation precision. And the look-up table is used to store polynomial coefficients for reducing the computational load. The simulation results indicate that the proposed method provides high simulation precision and fast convergence speed.