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应用科学学报

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低信噪比下调制信号载波相位的迭代估计

李明，郑辉
  

  1. 信号盲处理国家重点实验室 四川 成都 610041
  • 收稿日期:2007-07-18 修回日期:2008-01-18 出版日期:2008-07-31 发布日期:2008-07-31

Improved Iterative Estimator of Carrier Phase for Modulated Signal at Low SNR

LI Ming, ZHENG Hui
  

  1. National Key Laboratory of Blind Signals Processing, Chengdu 610041, China
  • Received:2007-07-18 Revised:2008-01-18 Online:2008-07-31 Published:2008-07-31

被引次数

1

摘要： 提出了一种低信噪比下期望－极大值（EM）迭代估计载波相位的改进算法。对期望－极大值算法采用新的一种并行初始化方式，在可能的相位区间设置多个初始值，并对初始化后第1次迭代进行了最优选择。经过这种处理不仅可以有效克服EM算法可能收敛到局部最大值点的问题，还可以解决非数据辅助（NDA）条件下的相位模糊问题，避免了对导频序列的需求。实验结果表明，该算法能够在低信噪比下获得比以往算法更好的估计性能，而且这种并行方式的运算量大大降低，收敛的速度和稳定性都得到了保证，具有实用价值。

关键词: 低信噪比, 期望－极大值迭代估计, 并行初始化, 相位模糊

Abstract: An improved iterative expectation-maximization estimator of carrier phase at low SNR is proposed. A new method of parallel initialization is provided, which gives multi-initialization at possible phase space and selects the best result as the new initialization after the first EM iterative process. Thus the EM algorithm can avoid convergence at local maximum and solve the phase ambiguity problem without the aid of a pilot sequence. Simulation results show that the proposed technique performs better than some previous methods, and is convenient to implement with lower complexity and faster convergence.

Key words: low SNR, EM iterative estimation, parallel initialization, phase ambiguity