| In the wireless mobile channel, to realize high speed and high quality service is the target and requirement of wireless communications. Orthogonal Frequency Division Multiplexing (OFDM) has attracted more and more attention for its high spectrum efficiency and strong immunity to multi-path interference in the wireless communications. However, it leads interference of OFDM symbols and inter-carrier, system performance degradation due to the uncertainty of OFDM symbol time of arrival, deviation of the oscillator between the receiver and transmitter, Doppler frequency shift and other factors. Therefore, synchronization of system is particularly important.Firstly, this paper introduces the principle of OFDM system and its characteristics, analyzes the impact of system performance for the various types of synchronization. There are two algorithms of non-blind synchronization estimation and blind synchronization estimation currently, but the focus of this paper is mainly non-blind synchronization estimation. The text describes in detail maximum likelihood estimation algorithm based on cyclic prefix and synchronization algorithm based on training sequence.Secondly, based on the training sequence synchronization algorithm, proposes a method of completing symbol timing synchronization that using the new training sequence. It compared with applying algorithm and existing algorithm by computer simulation, analyzes disadvantage and advantage of several algorithms and provides a direction for further research.Finally, this paper proposes a method of symbol timing synchronization applying mismatch sequence. According to its own characteristics and features, through the MATLAB simulation, it compared with new method and the synchronization estimation method using m-sequence in bad channel environment. Simulation result confirms feasibility of the mismatch sequence applied to the actual communication systems. |
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