LSC-DSSS信号长短伪码盲估计

短码扩频长码加扰的直扩信号可视为特殊的长码直扩信号，将其短扩频码和长扰码作为复合码。首先通过特征值分解和酉矩阵去位置模糊实现复合码的盲估计；然后利用m序列的三阶相关函数特性识别短扩频码的类型；最后根据识别结果采用三阶相关法或延迟三阶相关法实现长短伪码的盲估计。仿真表明，复合码估计在信噪比-7.5dB以上可达到1%以下的误码率；当信噪比高于-6dB时，三阶相关法估计长短伪码本原多项式的正确率可以达到90%以上；当信噪比高于-4dB时，延迟三阶相关法估计长短伪码序列的误码率低于1%。 

Blind Estimation of Long and Short PN Code in LSC-DSSS Signals

The LSC-DSSS signal can be regarded as special long code DSSS signal, taking the short spreading code and the long scrambling code together as the composite code. Firstly, the composite code can be estimated blindly by using the eigenvector decomposition and the unitary matrix method of eliminating fuzzy relations. And then the type of short code can be identified by using properties of the triple correlation function(TCF) of m sequence. Finally, according to the results of identification, the long and short PN codes are blindly estimated by using TCF method or delayed TCF method. Simulations show that the bit error rate of composite code sequence is below 1% when the signal-to-noise ratio(SNR) is greater than -7.5dB. The correct rate of the primitive polynomial of long and short code can reach to 90% when the TCF method is used and the SNR is above -6dB. The bit error rate of long and short code sequence can be reduced to 1% when the delayed TCF method is used and the SNR is above -4dB.