随着卫星定位技术(Global Positioning System,GPS)在室外定位中的深入应用,人们在室外环境下对位置服务(Location Based Service,LBS)愈加依赖,而室内环境中的定位技术还有待发展。本文主要研究了目前室内环境下的主流定位技术及其解...随着卫星定位技术(Global Positioning System,GPS)在室外定位中的深入应用,人们在室外环境下对位置服务(Location Based Service,LBS)愈加依赖,而室内环境中的定位技术还有待发展。本文主要研究了目前室内环境下的主流定位技术及其解决方案,并将其优缺点进行了对比分析,最终给出选择超宽带定位技术的原因。同时,还分析了超宽带定位技术的基本原理及最终选择TDOA算法的原因,并给出求解其后续非线性方程组的建议。简述了在室内环境下影响移动目标精准定位的主要因素,其中,因为非视距传播最能影响信号传播,所以针对降低其对精度的影响力进行了相关算法介绍。展开更多
针对矿井TOA(Time of Arrival)定位精度易受电磁波NLOS(Non Line of Sight)传播时延的影响,且不能满足井下应急救援、人员作业管理以及矿井物联网建设等需求的问题,通过对NLOS时延参考模型和矿井巷道设备运动特点的分析,将巷道电磁波NLO...针对矿井TOA(Time of Arrival)定位精度易受电磁波NLOS(Non Line of Sight)传播时延的影响,且不能满足井下应急救援、人员作业管理以及矿井物联网建设等需求的问题,通过对NLOS时延参考模型和矿井巷道设备运动特点的分析,将巷道电磁波NLOS传播时延分为随机NLOS时延和固定NLOS时延,结合两类NLOS时延造成测距误差的特点,提出了基于改进卡尔曼滤波和参数拟合的矿井TOA定位方法。为了消除由矿井巷道中机车等移动设备以及不规律设置设备引起的、具有随机性和难以定量分析等特点的巷道随机NLOS时延误差,设计了将新息阈值引入卡尔曼滤波器中,提高其系统对脉冲误差的滤除能力的方法;为了抑制由矿井巷道中固定设施及设备造成的具有稳定性的巷道固定NLOS时延误差,建立了巷道测距误差模型,构建了井下固有设备参数与定位估计值间的函数关系,通过参数拟合与投影几何算法来提高系统的定位精度。仿真结果显示,测量数据经过基于新息阈值的卡尔曼滤波器处理之后,误差曲线趋于平稳,定位误差保持在1.9~3.1m,再经参数拟合和几何算法处理后,定位误差在0~0.8m,平均误差由2.4m降为0.3m;且相比于SDS-TWR(Symmetric Double-Sided Two-Way Ranging)方法、卡尔曼滤波和指纹定位方法以及卡尔曼滤波和参数拟合方法,所提方法平均定位误差分别减小了3.4,0.4和0.6m。从而表明所提方法对TOA定位误差具有较明显的抑制作用,可以实现TOA方法在矿井NLOS环境中的有效应用。展开更多
With rapid advances of solar blind ultraviolet LED and ultraviolet detecting technology in recent years, ultraviolet communication gradually becomes a research hotspot due to its inherent advantages: low solar backgro...With rapid advances of solar blind ultraviolet LED and ultraviolet detecting technology in recent years, ultraviolet communication gradually becomes a research hotspot due to its inherent advantages: low solar background noise, non-line-of-sight(NLOS) and good secrecy. The strong scattering characteristics in atmospheric render ultraviolet waveband the ideal choice for achieving NLOS optical communication. This paper reviews the research history and status of ultraviolet communication both in China and abroad, and especially introduces three main issues of ultraviolet communication: channel model, system analysis and design, light sources and detectors. For each aspect, current open issues and prospective research directions are analyzed.展开更多
In the process of indoor localization,the existence of the non-line of sight(NLOS)error will greatly reduce the localization accuracy.To reduce the impact of this error,a 3 dimensional(3D)indoor localization algorithm...In the process of indoor localization,the existence of the non-line of sight(NLOS)error will greatly reduce the localization accuracy.To reduce the impact of this error,a 3 dimensional(3D)indoor localization algorithm named LMR(LLS-Minimum-Residual)is proposed in this paper.We first estimate the NLOS error and use it to correct the measurement distances,and then calculate the target location with linear least squares(LLS)solution.The final nodes location can be obtained accurately by NLOS error mitigation.Our algorithm can work efficiently in both indoor 2D and 3D environments.The simulation results show that the proposed algorithm has better performance than traditional algorithms and it can significantly improve the localization accuracy.展开更多
An all-fiber sensor based on a cascaded optical fiber device is proposed and demonstrated, and its sensor head is composed of a core-offset Mach-Zehnder interferometer(MZI) and a long-period fiber grating(LPFG). In th...An all-fiber sensor based on a cascaded optical fiber device is proposed and demonstrated, and its sensor head is composed of a core-offset Mach-Zehnder interferometer(MZI) and a long-period fiber grating(LPFG). In the experiment, two dips shaped by the intermodulation between the interference fringe of MZI and the resonant wavelength of LPFG are monitored. Experimental results show that temperature sensitivities of two dips are 0.060 7 nm/°C and 0.056 3 pm/°C, and the refractive index(RI) sensitivities are –18.025 nm/RIU and –55.06 nm/RIU, respectively. The simultaneous measurement of the temperature and external RI is demonstrated based on the sensitive matrix. Its low fabrication cost, simple configuration and high sensitivity make this sensor have potential applications in chemical and biological sensing.展开更多
文摘随着卫星定位技术(Global Positioning System,GPS)在室外定位中的深入应用,人们在室外环境下对位置服务(Location Based Service,LBS)愈加依赖,而室内环境中的定位技术还有待发展。本文主要研究了目前室内环境下的主流定位技术及其解决方案,并将其优缺点进行了对比分析,最终给出选择超宽带定位技术的原因。同时,还分析了超宽带定位技术的基本原理及最终选择TDOA算法的原因,并给出求解其后续非线性方程组的建议。简述了在室内环境下影响移动目标精准定位的主要因素,其中,因为非视距传播最能影响信号传播,所以针对降低其对精度的影响力进行了相关算法介绍。
文摘针对矿井TOA(Time of Arrival)定位精度易受电磁波NLOS(Non Line of Sight)传播时延的影响,且不能满足井下应急救援、人员作业管理以及矿井物联网建设等需求的问题,通过对NLOS时延参考模型和矿井巷道设备运动特点的分析,将巷道电磁波NLOS传播时延分为随机NLOS时延和固定NLOS时延,结合两类NLOS时延造成测距误差的特点,提出了基于改进卡尔曼滤波和参数拟合的矿井TOA定位方法。为了消除由矿井巷道中机车等移动设备以及不规律设置设备引起的、具有随机性和难以定量分析等特点的巷道随机NLOS时延误差,设计了将新息阈值引入卡尔曼滤波器中,提高其系统对脉冲误差的滤除能力的方法;为了抑制由矿井巷道中固定设施及设备造成的具有稳定性的巷道固定NLOS时延误差,建立了巷道测距误差模型,构建了井下固有设备参数与定位估计值间的函数关系,通过参数拟合与投影几何算法来提高系统的定位精度。仿真结果显示,测量数据经过基于新息阈值的卡尔曼滤波器处理之后,误差曲线趋于平稳,定位误差保持在1.9~3.1m,再经参数拟合和几何算法处理后,定位误差在0~0.8m,平均误差由2.4m降为0.3m;且相比于SDS-TWR(Symmetric Double-Sided Two-Way Ranging)方法、卡尔曼滤波和指纹定位方法以及卡尔曼滤波和参数拟合方法,所提方法平均定位误差分别减小了3.4,0.4和0.6m。从而表明所提方法对TOA定位误差具有较明显的抑制作用,可以实现TOA方法在矿井NLOS环境中的有效应用。
基金supported by the National High-tech R&D Program of China grant 2015AA043302the Basic research project of Shenzhen grant JCYJ20140417115840236
文摘With rapid advances of solar blind ultraviolet LED and ultraviolet detecting technology in recent years, ultraviolet communication gradually becomes a research hotspot due to its inherent advantages: low solar background noise, non-line-of-sight(NLOS) and good secrecy. The strong scattering characteristics in atmospheric render ultraviolet waveband the ideal choice for achieving NLOS optical communication. This paper reviews the research history and status of ultraviolet communication both in China and abroad, and especially introduces three main issues of ultraviolet communication: channel model, system analysis and design, light sources and detectors. For each aspect, current open issues and prospective research directions are analyzed.
基金supported in part by the foundation of Nanjing University of Posts and Telecommunications (No. NY215164)by the National Experimental Teaching Demonstration Centre Reform Project: Virtual 201106+2 种基金supported by the Key University Science Research Project of Jiangsu Province under Grant (No. 14KJA510003)supported by the Postgraduate Research & Practice Innovation Program of Jiangsu Province under Grant No. SJCX19_0275supported by the National Natural Science Foundation under grant No. 61771257, No. 61605085 and No.61571233, No.61871232
文摘In the process of indoor localization,the existence of the non-line of sight(NLOS)error will greatly reduce the localization accuracy.To reduce the impact of this error,a 3 dimensional(3D)indoor localization algorithm named LMR(LLS-Minimum-Residual)is proposed in this paper.We first estimate the NLOS error and use it to correct the measurement distances,and then calculate the target location with linear least squares(LLS)solution.The final nodes location can be obtained accurately by NLOS error mitigation.Our algorithm can work efficiently in both indoor 2D and 3D environments.The simulation results show that the proposed algorithm has better performance than traditional algorithms and it can significantly improve the localization accuracy.
基金supported by the National High Technology Research and Development Program(No.2013AA014200)the National Natural Science Foundation of China(No.61107052)+1 种基金the Natural Science Foundation of Tianjin(No.14JCYBJC16500)the Tianjin University's Science and Technology Development Fund Projects(No.2012)
文摘An all-fiber sensor based on a cascaded optical fiber device is proposed and demonstrated, and its sensor head is composed of a core-offset Mach-Zehnder interferometer(MZI) and a long-period fiber grating(LPFG). In the experiment, two dips shaped by the intermodulation between the interference fringe of MZI and the resonant wavelength of LPFG are monitored. Experimental results show that temperature sensitivities of two dips are 0.060 7 nm/°C and 0.056 3 pm/°C, and the refractive index(RI) sensitivities are –18.025 nm/RIU and –55.06 nm/RIU, respectively. The simultaneous measurement of the temperature and external RI is demonstrated based on the sensitive matrix. Its low fabrication cost, simple configuration and high sensitivity make this sensor have potential applications in chemical and biological sensing.
