基于分层处理的短码直扩信号盲解扩算法
|
摘要
针对实际截获的短码直扩(Direct Sequence Spread Spectrum,DSSS)信号信噪比存在波动、以及在低信噪比下伪噪声(Pseudo Random,PN)码盲估计困难的问题,提出了分层解调与解扩的处理方法。该算法将信噪比存在较大起伏的信号分为两层进行处理,首先从筛选出的高信噪比信号中估计扩频周期、短码序列起始位两个参数,然后利用估计出的参数,通过滑动窗口法实现全部信号的盲解扩。算法直接对调制过的BPSK信号进行处理,不需要数字相干信号、不需要估计PN码序列。仿真实验表明,用于参数估计的部分信号信噪比为0dB时,可以实现信噪比大于等于-12dB的信号的准确解扩。
Aiming at the fact that the signal-to-noise ratio(SNR)of real BPSK/DSSS signal often undulates,and that it is hard to estimate the pseudo-noise sequence under severe noisy circumstances,a method which hierarchically demodulate and despread signal was proposed.The algorithm firstly figured out the pseudo-noise sequence by using a sample from the received signal with high SNR,where coherent demodulation was employed.Then,by using the estimated pseudo-noise sequence the entire signal could be despread and demodulated in a cooperative way.Simulation showed the algorithm's performance curves under various SNR values,and the results showed that,by using the proposed method,effective despreading could be achieved when treating signal with undulating SNR values.
Aiming at the fact that the signal-to-noise ratio(SNR)of real BPSK/DSSS signal often undulates,and that it is hard to estimate the pseudo-noise sequence under severe noisy circumstances,a method which hierarchically demodulate and despread signal was proposed.The algorithm firstly figured out the pseudo-noise sequence by using a sample from the received signal with high SNR,where coherent demodulation was employed.Then,by using the estimated pseudo-noise sequence the entire signal could be despread and demodulated in a cooperative way.Simulation showed the algorithm's performance curves under various SNR values,and the results showed that,by using the proposed method,effective despreading could be achieved when treating signal with undulating SNR values.
引文
[1]Bouder C,Azou S,Burel G.A robust synchronization procedure for blind estimation of the symbol period and the timing offset in spread spectrum transmissions[C]//IEEE Seventh International Symposium on Spread Spectrum Techniques and Applications.US:IEEE,2002:238-241.
[2]Bouder C,Azou S,Burel G.Performance analysis of a spreading sequence estimator for spread spectrum transmissions[J].Journal of the Franklin Institute,2004,341(7):595-614.
[3]Tsatsanis M K,Giannakis G B.Blind estimation of direct sequence spread spectrum signals in multipath[J].Signal Processing IEEE Transactions on,1995,45(5):403.
[4]Peng Y,Tang B,Lu M.Fast method for spreading sequence estimation of DSSS signal based on maximum likelihood function[J].Journal of Systems Engineering&Electronics,2010,21(6):948-953.
[5]付卫红,杨小牛,刘乃安.基于盲源分离的CDMA多用户检测与伪码估计[J].电子学报,2008,36(7):1319-1323.
[6]任啸天,徐晖,王翔,等.一种针对短码、周期长码直扩信号扩频序列盲估计方法[J].宇航学报,2011,32(12):2596-2600.
[7]张花国,李鑫,张建华,等.基于半定松弛的长码DSSS信号扩频波形估计[J].电子学报,2016,44(2):334-339.
[8]张天骐.直扩信号的盲处理[M].北京:国防工业出版社,2012.
[9]谢然,张效义,田鹏武.一种基于循环谱的MPSK信号符号速率估计方法[J].计算机应用研究,2011,28(6):2294-2296.
[10]邓自立,许燕.基于Kalman滤波的白噪声估计理论[J].自动化学报,2003,29(1):521-524.
[11]孟宪波,鲍长春.基于最小控制GARCH模型的噪声估计算法[J].电子学报,2016,44(3):747-752.
[12]劳子轩,刘子扬,彭涛,等.全盲频谱感知:噪声估计与能量检测联合迭代算法[J].电子与信息学报,2013(8):1958-1963.
[13]张雪梅.直扩信号检测与参数估计方法研究[D].西安:西安电子科技大学,2014.
[2]Bouder C,Azou S,Burel G.Performance analysis of a spreading sequence estimator for spread spectrum transmissions[J].Journal of the Franklin Institute,2004,341(7):595-614.
[3]Tsatsanis M K,Giannakis G B.Blind estimation of direct sequence spread spectrum signals in multipath[J].Signal Processing IEEE Transactions on,1995,45(5):403.
[4]Peng Y,Tang B,Lu M.Fast method for spreading sequence estimation of DSSS signal based on maximum likelihood function[J].Journal of Systems Engineering&Electronics,2010,21(6):948-953.
[5]付卫红,杨小牛,刘乃安.基于盲源分离的CDMA多用户检测与伪码估计[J].电子学报,2008,36(7):1319-1323.
[6]任啸天,徐晖,王翔,等.一种针对短码、周期长码直扩信号扩频序列盲估计方法[J].宇航学报,2011,32(12):2596-2600.
[7]张花国,李鑫,张建华,等.基于半定松弛的长码DSSS信号扩频波形估计[J].电子学报,2016,44(2):334-339.
[8]张天骐.直扩信号的盲处理[M].北京:国防工业出版社,2012.
[9]谢然,张效义,田鹏武.一种基于循环谱的MPSK信号符号速率估计方法[J].计算机应用研究,2011,28(6):2294-2296.
[10]邓自立,许燕.基于Kalman滤波的白噪声估计理论[J].自动化学报,2003,29(1):521-524.
[11]孟宪波,鲍长春.基于最小控制GARCH模型的噪声估计算法[J].电子学报,2016,44(3):747-752.
[12]劳子轩,刘子扬,彭涛,等.全盲频谱感知:噪声估计与能量检测联合迭代算法[J].电子与信息学报,2013(8):1958-1963.
[13]张雪梅.直扩信号检测与参数估计方法研究[D].西安:西安电子科技大学,2014.