一种针对短码、周期长码直扩信号扩频序列盲估计方法

摘要

提出一种新的针对短码和周期长码直接序列扩频( DSSS,Direct Sequence Spread-Spectrum)信号的扩频序列盲估计方法.将周期长码DSSS信号建模为多用户短码DSSS信号系统,根据接收信号相关矩阵最大特征值个数,判断一个PN周期内调制信息符号个数,依此盲估计信息速率,同时形成分段相关矩阵矢量.利用改进二阶统计盲辨识( SOBI,Second Order Blind Identification)算法盲估计多用户分段DSSS的PN序列,根据特定约束条件(如m序列、Gold序列)去分段相位模糊,最终形成周期长码PN序列.仿真结果表明该算法的有效性,且适应较低信噪比.%A new method to blindly estimate the PN sequence of short-code ( SC ) and periodic long-code ( PLC ) direct sequence spread spectrum signals (DS-SS) is presented in this paper. The PLC DSSS signal is modeled as an multi-user short-code DSSS system. The information rate is blindly estimated according to the number of information symbols modulated during a period of spreading sequence according to the number of eigen-values of the received signal correlation matrices. This enables us to exploit an improved second order blind identification ( SOBI) to estimate users' spreading sequence, and make use of special constraint condition (such as m- or Gold-sequence) to eliminate the phase ambiguity, and form the blind estimation of long-code PN sequence lastly. Simulations show that the proposed method can provide a good estimation for all kinds DSSS signals in non-cooperative context, even in low signal-to-noise (SNR).