Study On Symbol Timing Synchronization Of OFDM

Orthogonal frequency division multiplexing (OFDM) has become the key technique in broadband wireless access and the next generation mobile communication system. Extensive attentions have been paid to OFDM due to its high spectral efficiency, high data rate and well anti-multipath ability. As a special muticarrier modulation, OFDM is very sensitive to timing synchronization error. And now symbol timing synchronization in OFDM has become a hotspot in the research of modern communication.This paper mostly focuses on the symbol timing synchronization of OFDM. Firstly, the fundamental principles and synchronization technology of OFDM are briefly introduced, analyzing the effects of timing synchronization errors to the system performance. Secondly, many kinds of synchronization algorithms are introduced and discussed in detail, such as Schmidl&Cox's synchronization algorithm based on symbol timing and the carrier frequency. The improved algorithm is proposed by H.Minn to eliminate the timing plat of timing synchronization in Schmidl&Cox algorithm. Because of approximate correlation factor, Minn algorithm has many side peaks and no steep symbol timing main peak.Based on analyses of the existing algorithms, new approach is introduced with time training sequence. The even number bits of training sequence send real sequence, modulated by IFFT and obtained inverse conjugate sequence. Based on the characteristics of this conjugate sequence, the measure function of new algorithm can be derived. Simulation results indicate that the new approach has higher accuracy to mean square error than the known model in additive white gaussian channel.