中文摘要：

在正交频分复用（orthogonal frequency division multiplexing, OFDM）系统接收端，错误估计快速傅里叶变换窗口起始点会导致OFDM帧偏差，从而造成严重的符号间干扰（inter symbol interference，ISI）以及子载波间干扰（inter carrier interference，ICI）。首先建立一个带有帧同步的OFDM系统模型，然后通过理论椎导得到帧偏差对OFDM系统的影响。利用伪随机序列自身较好的相关特性，设计了一种基于伪随机序列前导码的帧同步算法，并分析了3种基于循环前缀（eydi cprefix，CP）的传统帧同步算法。通过仿真实验，结果表明所提出的基于伪随机序列前导码的帧同步算法与传统算法相比，即使在较差的信道条件下，如在较低的信噪比或存在较大的载波频率偏移（carrier frequency offset，CF0）时，其帧偏差估计结果更为准确、稳定以及节省资源。

英文摘要：

At the receiver of an orthogonal frequency division multiplexing （OFDM） system, the wrong es- timation for the start point of fast Fourier transform （FFT） windows can lead to a frame offset of OFDM sym- bols, which can bring severe inter symbol interference （ISI） and inter carrier interference （ICI） for an OFDM system and decrease the OFDM modulation performance. Firstly, an OFDM system model with frame synchro- nization is built up. Then the influence of frame offset on the OFDM system is deduced theoretically. Conse- quently, an improved frame synchronization algorithm based on pseudo-noise （PN） sequence preamble is deve- loped by utilizing the relative good correlation characteristics of PN sequence. Three kinds of classical frame synchronization algorithms based on cyclic prefix （CP） are alse introduced. A group of simulation experiments are performed to compare and analyze the classical and improved algorithms. The simulation results indicate that the frame offset estimation results of the PN preamble based algorithm is much more accurate, stable and re- source-saving than the classical algorithms, even though under poor channel conditions, such as lower signal-to- noise ratio （SNR） or larger carrier frequency offset （CFO）.