Adaptive predistorter using NLMS algorithm for nonlinear compensation in visible-light communication system

A predistortion method using the adaptive normalised least mean square (NLMS) algorithm is proposed for the estimation of light-emitting diode distortion. The light emission characteristic could change nonlinearly depending on conditions of the physical environment, such as temperature variation, which cannot be ignored, especially in the case of high-power emissions. Instead of using the fixed values of the conventional memory look-up-table (LUT) for nonlinearity compensation, the proposed adaptive NLMS-based predistorter immediately estimates the distortion change according to environmental changes. The simulation results show that the proposed method has better performance than the conventional predistorter employing an LUT.