Tdd Baseband Key Technology Research In The System

In digital receiver in the TDD（Time Division Duplex）system, the symbolsynchronization technique is not only the basic technique in the baseband techniques,but also one of the most critical receiver functions in the synchronous communicationsystem. It has a decisive influence on the accuracy of the code in the digital receiver.The digital communications needs high-speed data transmission over band-limitedchannels. Hence, the channels are subject to inter symbol interference (ISI). The ISI is aprimary cause to degrade the performance of digital communication systems.Equalization applying after symbol synchronization is one of the techniques to mitigatethe effects of ISI.This thesis mainly deals with the bit synchronization and equalizationfor digital receiver.The main work and achievements of this paper are summarized as follows:1. This paper studys two common symbol synchronization methods in a digitalcommunication: the Gardner algorithm-based synchronizer and Mueller-Mulleralgorithm-based synchronizer. The author analyzs the two synchronization methods andsimulates them in simulink. Because Mueller-Muller algorithm-based synchronizer issubjected to carrier phase offset and frequency offset, but the Gardner algorithm-basedsynchronizer is not, the Gardner algorithm-based synchronizer is suitable for thisproject realization.2. The paper systematically studys and summarizes the basic theory of blindequalization.The author focuses on analyzing Constant Modulus Algorithm (CMA) andModified Constant Modulus Algorithm (MCMA), simulates them in Simulink andobserves the constellation diagram before and after the equilibrium. Because theMCMA equalizer can effectively overcome the phase rotation, but CMA can not, theMCMA equalizer is suitable for applying in the digital receiver.