The DSP Algorithm Design And Implementation For The System Of Digital Pre-distortion

In this thesis the power amplifier characteristics are analyzed together with the nonlinearity distortion reason, and study the status and prospects of the pre-distortion technology native and abroad. Including the new material used, technology on the RF, PA and many other ways by digital signals processing, and one of the most important is digital pre-distortion, which has been widely used recently for its easy controlling and low costPresently, the technology of DPD(digital pre-distortion) mainly focus on the 3rd generation of communication, especially the research concentrated more on the system of TD-SCAMA and WCDMA, and less on the GSM. It shows that the nonlinearity is still evidence in the GSM system, and result in backing off the input power, and decreasing the efficiency of the power amplifier. So it is very important to research the technology of the DPD base on the GSM system for it will be a long time to exist with the 3rd generation of communication system together.This thesis pay more attention on the principle of the digital pre-distortion, and the PA model which is widely used, the most important thing is to simulator the performance of the DPD system through Lest- Square algorithm in mat lab with the memory polynomial model and show that it could achieve the target and improve the linearity of the PA.Briefly, the implementations of DPD with the structure of memory polynomial model include two kinds of work:First, with the approximate math function of PA model, and the ways of digital signal processing such as correlation, matrix inversion and etc, to gain the coefficient for digital pre-distortion.Second, collect the useful data and complete the multiplication of the coefficient and the structure of memory polynomial to achieve the pre-distortion.The main job of this thesis is to complete the first work; the simulation is completed through the mat lab and the implementation through the DSP. Details including:1,estimate the delay of the system exactly;2,adjust the distortion both of amplitude and angle;3,the implementation of least-Square algorithm using C programming; 4,the proper way for matrix inversion;5,the drive design of DSP;6,testing the system with kinds of targets.At the same time, a new scheme is proposed for rapid algorithm design and implementation which can speedup the way from design to implementation. And finally, the result of the experimentation show that this kind of DPD technology can significantly decreasing the nonlinear cased by the power amplifier and increasing the efficiency.