电子学报 ›› 2021, Vol. 49 ›› Issue (8): 1480-1488.DOI: 10.12263/DZXB.20200024

• 学术论文 • 上一篇    下一篇

基于ML的多径信道下直扩信号PN码和信道的联合盲估计

刘秋红, 许漫坤, 李天昀   

  1. 信息工程大学,河南 郑州 450001
  • 收稿日期:2019-12-25 修回日期:2020-08-19 出版日期:2021-08-25 发布日期:2021-08-25
  • 作者简介:刘秋红 女,1991年出生,江苏连云港人.现为信息工程大学研究生.研究方向为通信信号分析与处理.E-mail:1217283177@qq.com
    许漫坤 女,1977年出生,河南安阳人.现为信息工程大学副教授.研究方向为智能信号、图像处理与模式识别.
    李天昀 男,1979年出生,江西萍乡人.现为信息工程大学副教授、硕士生导师.研究方向为软件无线电、通信信号处理.

Joint Blind Estimation of PN Codes and Channels with Maximum Likelihood for DSSS Signals in Multipath Channels

Qiu-hong LIU, Man-kun XU, Tian-yun LI   

  1. Information Engineering University,Zhengzhou,Henan 450001,China
  • Received:2019-12-25 Revised:2020-08-19 Online:2021-08-25 Published:2021-08-25

摘要:

针对非协作通信下多径信道直接序列扩频信号伪随机(PN,Pseudorandom)码的估计难题,本文在分析信号二阶统计特性的基础上,提出了一种基于最大似然(ML,Maximum Likelihood)的PN码和多径信道联合盲估计的方法.该方法首先建立PN码和信道序列的最大似然数学模型,然后通过交替转换数学模型和使用迭代最小二乘投影(ILSP,Iterative Least Square Projection)算法实现PN码和多径信道的联合估计.为了进一步降低算法复杂度和避免矩阵求逆,本文给出了算法的自适应求解方式.此外,针对低信噪比下信道估计误差引起PN码的估计精度下降的问题,本文提出了一种基于迭代总体最小二乘投影的改进算法.所提算法不受PN码码型限制,并通过仿真实验验证了算法的有效性.

关键词: 直接序列扩频, 多径信道, 伪随机码, 最大似然, 迭代最小二乘投影, 总体最小二乘

Abstract:

To solve the problem of pseudorandom (PN) codes estimation for direct sequence spread spectrum (DSSS) signals over multipath channels in non-cooperative communication, based on analyzing the second-order statistics of the signals, a method for joint blind estimation of PN codes and channels with maximum likelihood (ML) is proposed. First, we establish a ML mathematical model of PN codes and multipath channels. Then, we iteratively transform the mathematical model and use the iterative least square projection (ILSP) algorithm to estimate the PN code and channel. Furthermore, to reduce the complexity of the algorithm and avoid the matrix inversion, we present an adaptive rule of our algorithm. Finally, to avoid the decrease of PN code estimation accuracy caused by the channel estimation error, especially under low signal-to-noise ratio, an improved algorithm based on the iterative total least squares projection (ITLSP) is presented. The proposed methods are applicable to all types of PN codes and the simulation results are presented to demonstrate the effectiveness of the algorithms.

Key words: DSSS, multipath channels, PN codes, maximum likelihood, iterative least square projection (ILSP), total least squares

中图分类号: