Timing Synchronization Method Based On Embedded Training Sequence For OFDM Systems

With the development of the mobile internet and multimedia business, it's a challenge that limited spectrum resources can't provide good and fast enough communication service to meet our requirement for better life. As an effective approach to transmit high-speed data, Orthogonal Frequency Division Multiplexing (OFDM) is considered to be one of the most important technologies for the next generation mobile communication.Because OFDM system is sensitive to time synchronization error and frequency offset. More efficient and accurate synchronization technique is the premise and guarantee for its application. Compared with other synchronization schemes, the synchronization method based on the training sequence for OFDM systems is the best one according to its speed, accuracy, ease of implementation. It has two different data-added approaches called the preamble and embedded synchronization. The embedded training sequence synchronization method, which embeds the training sequence directly into the OFDM symbol stream, has higher spectrum efficiency and wider application prospect for the next generation packet-based mobile communication service system, than the preamble method which sends synchronization information before the OFDM symbol.The thesis focuses on the timing synchronization of OFDM system, especially the embedded training sequence synchronization technique. First of all, on the base of OFDM basic principles description, OFDM system simulation model was constructed, and the topic of synchronization of OFDM system was discussed. Then, the embedded training sequence OFDM system was designed on the base of analyzing the classical preamble synchronization technique, corresponding timing synchronization algorithm was realized. Besides, an improved synchronization algorithm was proposed combining the correlation property of the embedded m-sequences and the cyclic prefix, which takes advantage of the time error information in the cyclic prefix. Simulation results show that the embedded scheme has low probability of error estimation, and the precision of improved timing algorithm is distinctly increased. At last, a new timing synchronization algorithm was proposed based on embedded constant amplitude zero autocorrelation (CAZAC) sequence. Compared with the synchronization scheme based on m-sequence, it has better precision. Moreover the sequence is easy to generate. In addition, the relationship between the length and power of the embedded training sequence and the performance of synchronization is researched for the OFDM systems.