直接序列扩频信号PN序列盲估计方法

Blind Estimation of PN Sequence of a Direct Sequence Spread Spectrum Signal

在非协作信息侦测情况下,提出了一种实用的直接序列扩频(DS-SS)通信信号PN码序列的快速盲估计方法。该方法根据DS-SS基带信号的特点,首先采用二阶循环统计量估计PN码周期,然后利用分段互相关平均估计PN码同步始点;并在准确预估计这2个参数的基础上,将接收信号以PN码周期分成多个时段,利用多重互相关方法估计PN码序列。理论分析与仿真表明,该方法在截获信号信噪比很低的情况下有很好的估计性能,且无需任何先验知识,对PN码码型也没有任何限制,是一种有效的快速盲估计方法。

An efficient method that can blindly estimate and synchronize to PN sequence of direct sequence spread spectrum （DS-SS） signal quickly is presented in a non-cooperative context. The method is based on the character of the DS-SS signal, firstly the period of PN sequence is estimated with a second-order cyclic-cumulant, and then the method of segmented cross-correlation is used to identify the synchronous start bit of the PN codes. The intercepted signal is divided into windows, from which the cross-correlation average is computed, and then the multiple correlations are utilized to estimate the PN sequence. Both theoretical analysis and simulations show that this method can get a good estimation without prior knowledge even if the intercepted signal is far below the noise, and it also has no hypothesis on the nature of the PN code sequence.