Research On Timing And Carrier Frequency Synchronization In OFDM Systems

This thesis focuses on the training symbol aided synchronization algorithms in OFDM systems. In the thesis the influence of timing offset and carrier frequency offset on OFDM system is analyzed first. And then some classical training symbol aided synchronization algorithms are introduced systemically, including Schmidl's algorithm, some improved algorithms based on Schmidl's algorithm, and some CAZAC sequence based algorithms. Based on the research on these algorithms, a new CAZAC sequence based training symbol with low PAPR(peak-to-average power ratio) is developed. According to its conjugation and symmetry, a new timing offset estimation method is proposed. The training symbol can also be repeated to formulate a new periodic training symbol. Based on the two repeated training symbols, a new timing and carrier frequency synchronization algorithm for OFDM systems is proposed. Besides the ambiguity function and cross-ambiguity function of the designed training symbol, the effect of non-linear channel as well as the effect of quantization on the synchronization in OFDM systems is discussed.