Research Of Synchronization Technology In OFDM Communication System

Orthogonal Frequency Division Multiplexing(OFDM) is a kind of multi-carrier modulation technology, with the advantages of high spectrum efficiency, high data transmission rate and anti-multipath fading capability, OFDM becomes the core technology of next-generation mobile communication and the field of broadband wireless access, and it was widespread concerned by researchers. However, the technology of OFDM has its inherent shortcomings such as being sensitive to synchronization error, timing error will cause inter-symbol interference (ISI), and the frequency offset will introduce inter-carrier interference (ICI). So it is extremely important to achieve precise symbol synchronization and carrier synchronization.At the beginning of this thesis,the system model and the basic Principle of OFDM system is introduced,then research and focus on the variety of synchronization algorithms and techniques with OFDM communication system, in addition it details the classical algorithms such as S&C and Park algorithm,and carry out the simulation analysis, from the simulation analysis, the classical algorithm is optimized and improved.There improved method is proposed in this paper for classical algorithms, first in view of Park algorithm for maximum symbolic measure can only be taken in the middle of symbols is improved, then the symbol synchronization technology of OFDM is optimized in the implementation process, and the most important is for the shortcomings of not high symbol timing accuracy resulted of the "plateau" area in S&C algorithm, otherwise the defects of estimates and corrects integral frequency offset and fractional frequency offset in Park algorithm, an improved synchronization algorithm of OFDM based on a single training sequence was proposed. This algorithm is based on the classical synchronization algorithm, through the redesign of training symbol, the pseudo-random sequence weighting factor is introduced by a new approach, in order to improve the accuracy of time-frequency synchronization estimate in OFDM, and improve the performance of the system.