The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve ...The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve communication in non-line-of-sight (NLOS) transmission mode. Compared to line-of-sight (LOS) transmission, NLOS transmission does not require alignment and can be adapted to various underwater environments. The scattering coefficients of seawater at different depths are different, which makes the scattering of light in different depths of seawater different. In this paper, the received optical power and bit error rate (BER) of the photodetector (PD) were calculated when the scattering coefficients of blue-green light in seawater vary from large to small with increasing depth for NLOS transmission. The results show that blue-green light in different depths of seawater in the same way NLOS communication at the same distance, the received optical power and BER at the receiver are different, and the received optical power of green light is greater than that of blue light. Increasing the forward scattering coverage of the laser will suppress the received optical power of the PD, so when performing NLOS communication, appropriate trade-offs should be made between the forward scattering coverage of the laser and the received optical power.展开更多
针对超宽带(ultra wide band,UWB)定位中影响定位精度的非视距(non line of sight,NLoS)传播误差问题,提出了一种基于Kalman滤波的NLoS误差二次消除方法.该方法利用NLoS误差与测量误差之间的相互独立性,借助Kalman滤波将NLoS误差从总误...针对超宽带(ultra wide band,UWB)定位中影响定位精度的非视距(non line of sight,NLoS)传播误差问题,提出了一种基于Kalman滤波的NLoS误差二次消除方法.该方法利用NLoS误差与测量误差之间的相互独立性,借助Kalman滤波将NLoS误差从总误差中单独分离出来,对其进行实时估计,并将该NLoS误差估计值作为NLoS误差辨别及测距值修正的依据.通过Kalman滤波对到达时间(time of arrival,TOA)测距值进行二次估计、鉴别及修正以提高TOA测距精度,从而实现室内复杂环境下的UWB精准实时定位.仿真实验结果表明:该方法不仅能够对NLoS误差实现良好的跟踪估计,对视距(line of sight,LoS)/NLoS环境转变也具有较强的灵敏感知能力,同时NLoS误差测距值在应用该方法后的定位性能逼近于LoS环境下的理想状态.展开更多
针对蜂窝移动通信定位技术中常见的非视距传播(NLOS)问题,提出了一种利用来波信号强度和来波方位角测量值的联合条件概率判决NLOS的算法(JCPDS-RA,joint conditional probability decision scheme with RSS and AOA),并将其与数据融合...针对蜂窝移动通信定位技术中常见的非视距传播(NLOS)问题,提出了一种利用来波信号强度和来波方位角测量值的联合条件概率判决NLOS的算法(JCPDS-RA,joint conditional probability decision scheme with RSS and AOA),并将其与数据融合定位技术相结合,提高定位精度。推导了NLOS环境下RSS和AOA的条件概率密度模型,给出了JCPDS-RA算法和数据融合流程图,并进行了仿真实验,结果表明,该算法有效地提高了定位精度并有一定的普适性。展开更多
文摘The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve communication in non-line-of-sight (NLOS) transmission mode. Compared to line-of-sight (LOS) transmission, NLOS transmission does not require alignment and can be adapted to various underwater environments. The scattering coefficients of seawater at different depths are different, which makes the scattering of light in different depths of seawater different. In this paper, the received optical power and bit error rate (BER) of the photodetector (PD) were calculated when the scattering coefficients of blue-green light in seawater vary from large to small with increasing depth for NLOS transmission. The results show that blue-green light in different depths of seawater in the same way NLOS communication at the same distance, the received optical power and BER at the receiver are different, and the received optical power of green light is greater than that of blue light. Increasing the forward scattering coverage of the laser will suppress the received optical power of the PD, so when performing NLOS communication, appropriate trade-offs should be made between the forward scattering coverage of the laser and the received optical power.
文摘针对超宽带(ultra wide band,UWB)定位中影响定位精度的非视距(non line of sight,NLoS)传播误差问题,提出了一种基于Kalman滤波的NLoS误差二次消除方法.该方法利用NLoS误差与测量误差之间的相互独立性,借助Kalman滤波将NLoS误差从总误差中单独分离出来,对其进行实时估计,并将该NLoS误差估计值作为NLoS误差辨别及测距值修正的依据.通过Kalman滤波对到达时间(time of arrival,TOA)测距值进行二次估计、鉴别及修正以提高TOA测距精度,从而实现室内复杂环境下的UWB精准实时定位.仿真实验结果表明:该方法不仅能够对NLoS误差实现良好的跟踪估计,对视距(line of sight,LoS)/NLoS环境转变也具有较强的灵敏感知能力,同时NLoS误差测距值在应用该方法后的定位性能逼近于LoS环境下的理想状态.
文摘针对蜂窝移动通信定位技术中常见的非视距传播(NLOS)问题,提出了一种利用来波信号强度和来波方位角测量值的联合条件概率判决NLOS的算法(JCPDS-RA,joint conditional probability decision scheme with RSS and AOA),并将其与数据融合定位技术相结合,提高定位精度。推导了NLOS环境下RSS和AOA的条件概率密度模型,给出了JCPDS-RA算法和数据融合流程图,并进行了仿真实验,结果表明,该算法有效地提高了定位精度并有一定的普适性。
