航空学报 > 2013, Vol. 34 Issue (6): 1389-1396   doi: 10.7527/S1000-6893.2013.0126

基于恒模特性的QPSK-DSSS信号扩频序列估计

张花国1,2, 魏平1   

  1. 1. 电子科技大学电子工程学院, 四川 成都 611731;
    2. 通信信息控制和安全重点实验室, 浙江 嘉兴 314033
  • 收稿日期:2012-11-10 修回日期:2013-02-25 出版日期:2013-06-25 发布日期:2013-03-01
  • 通讯作者: 张花国, Tel.: 028-61831099 E-mail: uestczhg@163.com E-mail:uestczhg@163.com
  • 作者简介:张花国 男, 博士, 讲师。主要研究方向: 复杂通信信号截获与分析。 Tel: 028-61831099 E-mail: uestczhg@163.com;魏平 男, 博士, 教授, 博士生导师。主要研究方向: 复杂通信信号截获与分析、 阵列信号处理。 Tel: 028-61836276 E-mail: pwei@uestc.edu.cn
  • 基金资助:

    国家自然科学基金(61201282);通信信息控制和安全重点实验室基金(9140C130304120C13064)

Spreading Sequence Estimation Based on Constant Modulus Property for QPSK-DSSS Signals

ZHANG Huaguo1,2, WEI Ping1   

  1. 1. School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China;
    2. Science and Technology on Communication Information Security Control Laboratory, Jiaxing 314033, China
  • Received:2012-11-10 Revised:2013-02-25 Online:2013-06-25 Published:2013-03-01
  • Contact: 10.7527/S1000-6893.2013.0126 E-mail:uestczhg@163.com
  • Supported by:

    National Natural Science Foundation of China (61201282);Science and Technology on Communication Information Security Control Laboratory Foundation (9140C130304120C13064)

摘要:

针对非合作低信噪比条件下的QPSK-DSSS信号,提出一种基于恒模特性的扩频序列估计算法。该算法首先将单用户QPSK-DSSS信号等效为两用户的BPSK-DSSS信号,其次通过对信号协方差矩阵进行特征分解,估计出由同相与正交两路扩频序列张成的二维信号子空间,最后利用扩频序列的恒模特性消除特征分解带来的酉阵模糊问题,实现扩频序列的精确估计。本文提出算法实现简单,相对目前现有传统算法具有较低的计算复杂度,而且计算机仿真表明:本文提出算法在低信噪比条件下具有优良的估计性能。

关键词: QPSK-DSSS信号, 扩频序列, 信号子空间, 恒模特性, 酉阵模糊

Abstract:

In this paper, a spreading sequence estimation algorithm based on constant modulus property is proposed for the QPSK-DSSS signals in low signal to noise ratio and non-cooperative scenarios. First, the single-user QPSK-DSSS signal can be equivalently represented as a two-user BPSK-DSSS signal, and then the two-dimensional signal subspace spanned by the in-phase and quadrature binary spreading sequences is estimated by the eigen-decomposition of the covariance matrix. Finally, to estimate the spreading sequences accurately, its constant modulus property is exploited to cope with the unitary matrix ambiguity resulting from eigen-decomposition. The proposed algorithm is simple and easy to implement, and has a lower computational complexity compared to existing methods. And simulation results demonstrate the significant performance gains of the proposed algorithm in low signal to noise ratio situations.

Key words: QPSK-DSSS signal, spreading sequence, signal subspace, constant modulus property, unitary matrix ambiguity

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