This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise （PN） sequence estimation in low signal to noise ratios （SNR） dire...This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise （PN） sequence estimation in low signal to noise ratios （SNR） direct sequence spread spectrum （DS-SS） signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.展开更多
为了扩大盲信噪比SNR的估计范围,同时降低计算的复杂性,提出了一种新的基于样本的协方差矩阵的信号子空间方法和联合信息标准(Combined information criterion,CIC)的盲信噪比估计算法。算法中采用的CIC克服了AIC(Akaike information cr...为了扩大盲信噪比SNR的估计范围,同时降低计算的复杂性,提出了一种新的基于样本的协方差矩阵的信号子空间方法和联合信息标准(Combined information criterion,CIC)的盲信噪比估计算法。算法中采用的CIC克服了AIC(Akaike information criterion)惩罚度较小和MDL(Minimum description length)惩罚度较大的缺点,并且推导出了CIC的最大似然形式。算法不需要信号调制方式、波特率和载波的先验知识。计算机仿真结果表明,该算法可以用小样本对在加性白高斯噪声和Rayleigh衰落信道下常用的数字调制方式进行盲估计,在SNR从-10 dB^25 dB范围内平均估计误差小于1 dB。展开更多
基于信号相位匹配原理,给出了利用由双平行线列阵组成的平面阵进行声源方位估计的奇异值分解算法(Singular Value Decomposition for Signal Phase Matching,SVDSPM),推导了空间谱搜索所需的时延计算公式;分析了双线阵间距对不同频率方...基于信号相位匹配原理,给出了利用由双平行线列阵组成的平面阵进行声源方位估计的奇异值分解算法(Singular Value Decomposition for Signal Phase Matching,SVDSPM),推导了空间谱搜索所需的时延计算公式;分析了双线阵间距对不同频率方位估计精度的影响,从而确定了双线阵的间距;分析了声源频率对方位估计精度的影响;给出了给定频率时方位估计精度与信噪比的关系并与MUSIC算法获得的结果进行了比较;给出了利用平面阵进行低空目标的声探测时存在的声探测盲区的描述方法,并分析了声源的频率、目标初始俯仰角、阵元数、阵型对声探测盲区的影响。仿真结果表明:(1)在低信噪比时SVDSPM算法的方位估计性能优于MUSIC算法;(2)声探测盲区的范围与声源的频率和目标初始俯仰角有关,而与阵元数、阵型无关。声探测盲区的分析和研究为立体阵的设计和方位估计提供了依据。展开更多
在MIMO-OFDM水声通信系统中,由于信道间的相互干扰和水声信道严重时延扩展产生的频率选择性衰落,系统的通信误码率较高。针对这一问题,研究了空频编码的MIMO-OFDM通信,提出空频迭代信道估计与均衡(Spatial Frequency Iterative Channel ...在MIMO-OFDM水声通信系统中,由于信道间的相互干扰和水声信道严重时延扩展产生的频率选择性衰落,系统的通信误码率较高。针对这一问题,研究了空频编码的MIMO-OFDM通信,提出空频迭代信道估计与均衡(Spatial Frequency Iterative Channel Estimation and Equalization,SFICEE)方法。该方法通过载波间的空频正交性进行各收发阵元对的信道估计,并通过空频均衡获得符号初始估计,迭代更新信道估计,而后通过符号后验软信息反馈进行迭代空频软均衡。仿真结果表明,当误码率为10^(-3)时,文中所提出的SFICEE方法经过二次迭代与STBC方法相比具有4.8 d B的性能增益,相对于SFBC方法有2.8 d B的性能提升。当输入信噪比相同时,文中所提出方法的星座图更加收敛,可以更好地降低水下通信系统的误码率。展开更多
基金supported by the National Natural Science Foundation of China (10776040 60602057)+4 种基金Program for New Century Excellent Talents in University (NCET)the Project of Key Laboratory of Signal and Information Processing of Chongqing (CSTC2009CA2003)the Natural Science Foundation of Chongqing Science and Technology Commission (CSTC2009BB2287)the Natural Science Foundation of Chongqing Municipal Education Commission (KJ060509 KJ080517)
文摘This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise （PN） sequence estimation in low signal to noise ratios （SNR） direct sequence spread spectrum （DS-SS） signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.
文摘为了扩大盲信噪比SNR的估计范围,同时降低计算的复杂性,提出了一种新的基于样本的协方差矩阵的信号子空间方法和联合信息标准(Combined information criterion,CIC)的盲信噪比估计算法。算法中采用的CIC克服了AIC(Akaike information criterion)惩罚度较小和MDL(Minimum description length)惩罚度较大的缺点,并且推导出了CIC的最大似然形式。算法不需要信号调制方式、波特率和载波的先验知识。计算机仿真结果表明,该算法可以用小样本对在加性白高斯噪声和Rayleigh衰落信道下常用的数字调制方式进行盲估计,在SNR从-10 dB^25 dB范围内平均估计误差小于1 dB。
文摘基于信号相位匹配原理,给出了利用由双平行线列阵组成的平面阵进行声源方位估计的奇异值分解算法(Singular Value Decomposition for Signal Phase Matching,SVDSPM),推导了空间谱搜索所需的时延计算公式;分析了双线阵间距对不同频率方位估计精度的影响,从而确定了双线阵的间距;分析了声源频率对方位估计精度的影响;给出了给定频率时方位估计精度与信噪比的关系并与MUSIC算法获得的结果进行了比较;给出了利用平面阵进行低空目标的声探测时存在的声探测盲区的描述方法,并分析了声源的频率、目标初始俯仰角、阵元数、阵型对声探测盲区的影响。仿真结果表明:(1)在低信噪比时SVDSPM算法的方位估计性能优于MUSIC算法;(2)声探测盲区的范围与声源的频率和目标初始俯仰角有关,而与阵元数、阵型无关。声探测盲区的分析和研究为立体阵的设计和方位估计提供了依据。
文摘在MIMO-OFDM水声通信系统中,由于信道间的相互干扰和水声信道严重时延扩展产生的频率选择性衰落,系统的通信误码率较高。针对这一问题,研究了空频编码的MIMO-OFDM通信,提出空频迭代信道估计与均衡(Spatial Frequency Iterative Channel Estimation and Equalization,SFICEE)方法。该方法通过载波间的空频正交性进行各收发阵元对的信道估计,并通过空频均衡获得符号初始估计,迭代更新信道估计,而后通过符号后验软信息反馈进行迭代空频软均衡。仿真结果表明,当误码率为10^(-3)时,文中所提出的SFICEE方法经过二次迭代与STBC方法相比具有4.8 d B的性能增益,相对于SFBC方法有2.8 d B的性能提升。当输入信噪比相同时,文中所提出方法的星座图更加收敛,可以更好地降低水下通信系统的误码率。
