基于正交特性的短码直扩信号伪码序列盲估计  

Blind estimation of PN sequence based on orthogonal characteristics for short-code direct sequence spread spectrum signals

作　　者：朱照阳[1] 高勇[1] 

机构地区：[1]四川大学电子信息学院,四川成都610065

出　　处：《系统工程与电子技术》2017年第9期2125-2131,共7页Systems Engineering and Electronics

基　　金：中央高校基本科研业务费专项资金(2082604194194)资助课题

摘　　要：在短码直扩信号伪码序列的估计中,当使用特征值分解(eigenvalue decomposition,EVD)算法、奇异值分解(singular value decomposition,SVD)算法和压缩投影逼近子空间跟踪(projection approximation subspace tracking with deflation,PASTd)算法来估计伪码序列时,存在着当最大特征值和次大特征值相近时最大特征向量会受到干扰,进而影响伪码序列估计的问题。针对此问题,提出了一种基于正交特性的伪码序列估计算法。在已知码片速率和伪码周期的前提下,该算法首先把接收信号划分成长度为两倍码元宽度、数据重叠50%的数据段,然后用SVD估计出最大特征向量和次大特征向量,由于最大特征向量和次大特征向量是相互正交的,可以利用两者的正交特性来估计扩频序列。该算法不但能在信号失步时间未知的情况下估计伪码序列,而且仿真结果表明该算法具有稳定性高,需要的数据量少和能在低信噪比下有较好的估计性能等优点。When using the eigenvalue decomposition algorithm,the singular value decomposition（SVD）algorithm and projection approximation subspace tracking with the deflation（PASTd）algorithm to estimate pseudo-noise（PN）sequence in the estimation of PN sequence of direct sequence spread spectrum signals,there is a problem that the maximum eigenvector will be disturbed when the largest eigenvalue and the next largest eigenvalue are close,which will affect the estimation of the spread spectrum sequence.To solve this problem,a spreading sequence estimation algorithm based on orthogonal characteristic is proposed.Firstly,the received signal is divided into data segments with the length of twice the symbol width and 50% of the data overlapping after the chip rate of PN sequence and the PN sequence period are estimated.Then the largest eigenvector and the next largest eigenvector are estimated by SVD.Finally,the spreading sequence can be estimated with both orthogonal characteristics.The algorithm can estimate spreading sequence without the knowledge of desynchronization time and the simulation results show that the algorithm has the advantages of high stability,less data required and good estimation performance at a low signal-to-noise ratio.

关 键 词：伪码序列 奇异值分解 特征值分解 子空间跟踪 正交特性 

分 类 号：TN914.42[电子电信—通信与信息系统]