摘要
提出一种基于循环移位前导序列的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统载波同步方法,该方法根据离散傅里叶变换(Discrete Fourier Transform,DFT)的时移性质,构造循环移位前导序列,并设计了两个频偏估计器。由估计器1完成粗同步,而精同步采用两个估计器的最优线性组合完成。在多径信道下优化估计器的设计,消除了均方误差中出现的地板效应。新算法与传统算法相比,估计范围大,运算精度高,且估计范围和精度可灵活调节。同时分析并得出了本估计方法的Cramer-Rao下限。仿真结果表明,新算法降低了均方误差和误码率,有效提高了系统性能。
A scheme based on cyclic-shifted preamble sequences is proposed for carrier frequency synchronization in OFDM system. According to the time property of DFT, the preamble sequences are constructed and two estimators are designed. The coarse frequency offset is realized by the first estimator. Once coarse frequency offset compensated, the fine estimation is achieved by the optimized linear combination of two estimators. In multi-path channel, two estimators are optimized in order to eliminate the floor phenomenon. Compared with the traditional algorithm, the new method has better estimation accuracy and larger estimation span, which can change more flexible. At the same time, the Cramer-Rao Lower Bound of the new method is analyzed and obtained. It is demonstrated that the algorithm can reduce MSE and BER, and improve the system performance significantly.
出处
《信息与电子工程》
2006年第5期326-330,共5页
information and electronic engineering
