Research On Synchronization And Channel Estimation In OFDM Systems

Orthogonal Frequency-Division Multiplexing(OFDM) has high spectrum efficiency and is robust to the multi-path fading. Owing to these advantages, OFDM has become the core technology in the fourth generation mobile communication systems. Whereas, some techniques in OFDM systems are still not consummate, especially in Synchronization and Channel Estimation.After the basic principle of OFDM systems was intrduced, this thesis firstly studies synchronization technology, based on the analysis of the influence of each kind of synchronization error on the system performance, the thesis focuses on the ML algorithm based on the cyclic prefix and S&C algorithm based on the training sequence and its improved algorithms, then carries on the simulation of various algorithms. Then the thesis focuses on the channel estimation, mainly researches the pilot-aided estimation technology, after the thesis studies the channel estimation algorithms based on the LS critirion or the MMSE criterion and their improved algorithms, the thesis researches the interpolation algorithms of non-pilot positions, at last, the thesis carries on the simulation analysis of each algorithm.Based on the research in the above, the thesis presents a combined synchronization and channel estimation algorithm for OFDM based on maximum likehood, in order to maximize the use of resources and improve the performances of system. Simulation results show the effectiveness of the proposed estimation algorithm.