An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extr...An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extraction of unsupervised neural networks are exploited adequately. Theoretical analysis and experimental results are provided to show that this approach can work well on the lower S/N ratio input signals.展开更多
This paper introduces a new theory and algorithm that can be used in blind detection of the carrier wave signal and the pseudo-random sequence of the direct sequence spread spectrum （DS/SS） signal with negative SNR....This paper introduces a new theory and algorithm that can be used in blind detection of the carrier wave signal and the pseudo-random sequence of the direct sequence spread spectrum （DS/SS） signal with negative SNR. First, without any a priori knowledge of the DS/SS signal, the carrier wave signal can be detected from DS/SS signal with negative SNR by using stochastic differential equations and energy detection method. Based on this, the pseudo-random sequence can also be blindly detected in DS/SS signal with negative SNR by reducing noise of the nonlinear signal and the algorithm of wavelet multiscale decomposition algorithm. Finally, the computer simulation shows that we can detect the carrier wave signal with SNR=-27 dB and the pseudo-random sequence under error code ratio 10^-4with SNR =-10 dB.展开更多
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
为使WiFi无线传感器网络能够利用单次获取的接收信号强度指示(Received Signal Strength Indication,RSSI)快速定位目标并减小RSSI阴影衰落对定位的影响,提出一种改进的基于Dempster-Shafer(DS)证据理论的利用RSSI信息对室内移动目标定...为使WiFi无线传感器网络能够利用单次获取的接收信号强度指示(Received Signal Strength Indication,RSSI)快速定位目标并减小RSSI阴影衰落对定位的影响,提出一种改进的基于Dempster-Shafer(DS)证据理论的利用RSSI信息对室内移动目标定位(Locating Indoor Mobile Target with RSSI based on DS evidence theory,LIMT-DS)的方法。LIMT-DS方法根据传感器接收到的RSSI值构造关于目标位置估计的条件概率密度函数,并据此通过改进的证据构造方法生成各传感器关于定位环境中位置点的证据,对各位置点进行证据综合,最后通过改进的决策模式选择出目标存在可能性较大的数个定位点进行位置加权,获得目标的位置估计。仿真与实验结果表明,LIMT-DS方法可以用传感器网络单次获得的RSSI信息实现对目标的定位,其定位性能明显优于同类方法。展开更多
文摘An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extraction of unsupervised neural networks are exploited adequately. Theoretical analysis and experimental results are provided to show that this approach can work well on the lower S/N ratio input signals.
基金the National Defence Key Foundation of China (Grant No. 614144)
文摘This paper introduces a new theory and algorithm that can be used in blind detection of the carrier wave signal and the pseudo-random sequence of the direct sequence spread spectrum （DS/SS） signal with negative SNR. First, without any a priori knowledge of the DS/SS signal, the carrier wave signal can be detected from DS/SS signal with negative SNR by using stochastic differential equations and energy detection method. Based on this, the pseudo-random sequence can also be blindly detected in DS/SS signal with negative SNR by reducing noise of the nonlinear signal and the algorithm of wavelet multiscale decomposition algorithm. Finally, the computer simulation shows that we can detect the carrier wave signal with SNR=-27 dB and the pseudo-random sequence under error code ratio 10^-4with SNR =-10 dB.
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.
文摘为使WiFi无线传感器网络能够利用单次获取的接收信号强度指示(Received Signal Strength Indication,RSSI)快速定位目标并减小RSSI阴影衰落对定位的影响,提出一种改进的基于Dempster-Shafer(DS)证据理论的利用RSSI信息对室内移动目标定位(Locating Indoor Mobile Target with RSSI based on DS evidence theory,LIMT-DS)的方法。LIMT-DS方法根据传感器接收到的RSSI值构造关于目标位置估计的条件概率密度函数,并据此通过改进的证据构造方法生成各传感器关于定位环境中位置点的证据,对各位置点进行证据综合,最后通过改进的决策模式选择出目标存在可能性较大的数个定位点进行位置加权,获得目标的位置估计。仿真与实验结果表明,LIMT-DS方法可以用传感器网络单次获得的RSSI信息实现对目标的定位,其定位性能明显优于同类方法。
