基于ZC序列的OFDM系统定时同步改进算法

为提高OFDM( Orthogonal Frequency Division Multiplexing) 系统的定时同步精确度，提出了一种改进的基于ZC( Zadoff-Chu) 序列的定时同步算法。该算法将经典的Minn 算法序列的取反方法与Park 算法的序列共轭方法结合，利用良好自相关性且低互相关性的ZC 序列，替代原有的PN( Pseudo-Noise Sequence) 序列，构成新序列结构。改进算法在定时位置发生错误时，仍能保证系统精确进行定时同步。在加性高斯白噪声( AWGN:Additive White Gaussian Noise) 信道，子载波的数量是256，16QAM( Quadrature Amplitude Modulation) 调制和解调下，Matlab 仿真表明改进算法消除了Minn 算法和Park 算法中副峰对定时同步的影响，定时偏差与均方误差( MSE: Mean Square Error) 在信噪比－ 15 ～ 15 dB 内，较于Minn 算法和Park 算法更低，提高了定时精度。信噪比是15 dB 时，改进算法定时均方误差为4． 2 × 10 － 6 ，是估计性能最优状态。

Improved Timing Synchronization Algorithm for OFDM System Based on ZC Sequence#br#

An improved timing synchronization algorithm based on ZC( Zadoff-Chu) sequence is proposed in order to improve timing synchronization accuracy of OFDM ( Orthogonal Frequency Division Multiplexing ) system． This algorithm combined the sequence inversion of Minn algorithm with the sequence conjugate of Park algorithm． The new sequences replaced PN sequences with ZC sequences that good autocorrelation and low crosscorrelation．Even in the timing position error，the system can still be precisely timing synchronized． Under the channel of AWGN ( Additive Gaussian White Noise) ，the number of subcarriers is 256，16QAM modulation and demodulation，Matlab simulation shows that the improved algorithm eliminates the influence of minor peak on timing synchronization in Minn algorithm and Park algorithm． Timing deviation and MSE ( Mean Square Error) are lower than Minn algorithm and Park algorithm within － 15 ～ 15 dB，which improves timing accuracy． When the SNR is 15 dB，the timing MSE of the improved algorithm is 4． 2 × 10 － 6，which is the optimal state for estimating performance．