Research On Nonlinear Modeling Technology Of LED Communication Based On Orthogonal Polynomial

In recent years,light-emitting diode technology called "green lighting" is rapidly developing.LED(Light-emitting Diode,light-emitting diode)communication or visible light communication is a promising field,and is receiving increasing attention from research.LED is the main source of non-linearity in LED communication;LED non-linear modeling is successful by using storage polynomials and a series of related compensation measures.However,there is numerical instability in the estimates of the stored polynomial coefficients,which leads to inaccurate modeling and poor optimization nonlinear performance.Therefore,it is necessary to effectively model the nonlinearity and optimize the nonlinearity through pre-distortion or post-distortion techniques to Avoid severe degradation in communication performance.The main work of this article is as follows:Through qualitative analysis and simulation,the output noise and non-linear distortion of the LED communication receiving front-end are studied.It is pointed out that the non-linear distortion is the most important factor restricting the LED communication.Firstly,the model of visible light communication system is introduced,and several classical LED mathematical models are given according to the nonlinear characteristics of LED.This paper proposes a nonlinear modeling technology based on orthogonal polynomials,which utilizes LED communication with pulse amplitude modulation(PAM)signal to search for effective LED nonlinear modeling and appropriate nonlinear optimization technology,so as to optimize the nonlinearity of LED communication and reduce ISI(inter-symbol Interference)distortion in the channelSecondly,a difficulty in line-of-sight LED communication is that multipath dispersion can cause ISI effects at high data rates.We extend the work of LED modeling technology based on orthogonal polynomials and take into account LED nonlinearity and ISI distortion due to LED memory effects and multipathdispersion.A joint estimation method of LED nonlinear and composite ISI channels based on orthogonal polynomial technology is proposed.The ISI optical channel and the non-linearity of the LED with memory effect can be jointly estimated and optimized;a low-complexity frequency-domain equalization is applied to eliminate the distortion effect caused by the LED memory effect and the optical ISI channel;Finally,a post-distorter is used to optimize LED nonlinearity without memory effect;simulation results show that the proposed technology can effectively deal with LED nonlinearity and ISI distortion effects.