中国空间科学技术

›› 2011, Vol. 31 ›› Issue (6): 58-64.doi: 10.3780/j.issn.1000-758X.2011.06.009

• 技术交流 • 上一篇    下一篇

正交频分复用系统中一种抗多径衰落的联合时频同步算法

 刘程贞1, 金蓬嘉1, 吴学英2   

  1. (1上海航天电子有限公司， 上海 201821）（2中国空间技术研究院， 北京 100094）
  • 收稿日期:2011-04-07 修回日期:2011-12-25 出版日期:2011-12-25 发布日期:2011-12-25
  • 作者简介:刘程贞 1983年生，2008年毕业于哈尔滨工业大学电子信息工程专业，现为上海航天技术研究院硕士研究生。研究方向为OFDM系统中的同步算法。

Robust Timing and Frequency Synchronization under Multipath Fading Channel for Orthogonal Frequency Division Multiplexing  Systems

LIU  Cheng-Zhen1, JIN  Peng-Jia1, WU  Xue-Ying2   

  1. （1 Shanghai Aerospace Electronic Co. Ltd, Shanghai 201821）（2 China Academy of Space Technology, Beijing 100094）
  • Received:2011-04-07 Revised:2011-12-25 Published:2011-12-25 Online:2011-12-25

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摘要： 在正交频分复用（Orthogonal frequency division multiplexing,OFDM）通信系统中提出了一种基于新颖训练序列的同步算法。该训练序列只使用了一个OFDM符号,并且具有中心对称和前后部分一致的双重结构。在进行完粗定时同步和小数倍频率同步后，使用逆快速傅里叶变换（IFFT）运算来进行精确的联合信道路径定时和整数倍频偏估计。IFFT运算使得算法复杂度得到较大简化并且估计速度增快。在精定时同步阶段，提出了信干比最大的准则来估计最佳定时位置，这一准则使得定时估计的精度更高。试验仿真表明：提出的同步算法比传统的同步算法在抗多径衰落和伪多径方面具有更加优越的性能。

关键词: 正交频分复用, 同步, 多径信道, 卫星通信

Abstract: A synchronization scheme for  orthogonal frequency division multiplexing (OFDM) systems based on a novel training sequence was proposed. The training sequence consists of only one centrosymmetric OFDM symbol with two identical parts to  achieve reliable timing and frequency accuracy in the time domain. After coarse timing and fractional frequency synchronization  achieved, a successful estimation was declared for both channel path timing and integer frequency offset by IFFT algorithm which can largely reduce the computational load of the algorithm. For fine timing synchronization, a metric called signal to interference ratio  （SIR）was devised. Based on this metric, a fine timing synchronization method was developed to improve the timing precision. Comparison of the proposed fine adjustment algorithm and conventional synchronization algorithms by using computer simulation illustrates  that the method is more robust to multipath and pseudo multipath.

Key words: Orthogonal frequency division multiplexing, Synchronization, Multipath channel , Satellite communication