The Correcting Algorithms And Simulation Of Carrier Frequency Offset In OFDM

Orthogonal Frequency Division Multiplexing(OFDM) is one of the key technologies in the mobile communication fields, it can realize the high rate data transmission in the wireless channels. It has been extensively applied in the wireless communication domain because of its high spectrum efficiency and good anti-multi-path interference ability. It will be one of the basic technologies in the future wireless broadband access system and it is promising to be a core technology of the fourth generation mobile communications. However, carrier frequency offset is the main drawbacks of OFDM system, it can make the SNR lower, cause loss of sub-carrier orthogonality, and thus can introduce inter-channel interference(ICI) and severely degrade the system performance.This thesis researches three correcting algorithms of carrier frequency offset around in theory and practice:the maximum likelihood algorithm based on circular prefix、the pilot symbol estimation algorithm based on the data aid and the blind estimation algorithm are researched:This thesis summarizes the emergence、development、principle、characteristics and the key technology of OFDM. According to the various synchroniazaiton error influence on the system’s performance, the thesis analyses the influence of the system performance and the performance simulation of frequency offset. Lists all kinds of typical algorithms of the OFDM synchronization algorithms and makes a brief to introduce and analyse them. The thesis detailedly analyses the synchronous algorithm based on CP. Takes the classical ML algorithm for example, analyses the theory of ML estimation method, and simulates it under the different channels. The thesis gives a new improved algorithm based on the ML algorithm and other related algorithms and simulates it under the multi-path channel. At the same time, the thesis deeply researches the typical S&C estimation algorithm which is based on the aid of pilot symbols and the improved algorithm of the S&C estimation algorithm, simulates these two algorithms under different channels and compares their performance. Classifies the blind synchronization algorithms, then briefly introduces the MUSIC algorithm and the ESPRIT algorithm which are based on subspace briefly, and then detailedly describes and analyses the blind synchronous algorithm based on the cycle stationarity characteristics and gives the advantages and disadvantages of the algorithm. At last, simulates the S&C algorithm、Kim algorithm、the improved S&C algorithm and blind synchronization algorithm based on the cycle stationarity characteristics and analyses their performance comparison.