Research And Realize Of Digital Pre-Distortion For Power Amplifier Based On Multi-Channel Frequency Hopping System

Multi-channel frequency hopping system is based on LINK 16 data link military communication systems.The working band is L band,using TD-SCDMA frame structure,and frequency hopping technology.The power amplifier is an important part of communication system in transmission link.However,when the transmit power gradually increases,the nonlinearity of the power amplifier will be more and more serious.Such non-linearities will generate many unnecessary interferences that affect the overall quality of the communication system.Therefore,the linearization of power amplifier seems to be very important.In multi-channel frequency hopping system,we mainly face three critical problems:The first problem is high power.The communication of long-distance transmission needs to consider the power level of the power amplifier.The second problem is multi-carrier features.Multi-channel frequency hopping signals and multi-carrier signals have the same spectral structure.This article uses a two-channel signal simulation instead of multi-channel.The third problem is the fast frequency hopping feature.The time for each signal is pretty short,so the adaptive time needs to be short enough.At first,this paper introduces the method and principle of linearization of power amplifier.Then it introduces the traditional method of digital predistortion and then proposes a new method.Digital predistortion is mainly divided into three parts:learning structure,amplifier model and adaptive algorithm.The innovation of this paper mainly aims at the innovation of pre-distortion learning structure.The traditional pre-distorted learning structure has many practical problems when it is directly applied to the frequency hopping communication system.Therefore,it is very important to change its learning structure and propose new feasible methods.In the second part of this article,this paper simulates and compares the traditional method and the new proposed method.In this summary,we will answer the above three major questions by using the simulation results.The last chapter presents the shortcomings and areas for improvement and the research plan for the next step.