Mathematical Formulations of Signal Propagation in Ultra-Wideband Transceiver Systems under a UWB Channel Environment with an Extension of Frequency Offset Correction

This paper analyzes mathematically the crucial aspects of signal processing in a Multi-Band (MB) Orthogonal Frequency Division Multiplexing (OFDM) based system considering Ultra-Wideband (UWB) channel environment. In the process of analysis, it emphasizes the significant features of UWB receiver design in comparison with ‘conventional’ narrow-band system. The analysis shows that the high dispersive nature of a frequency selective UWB channel effects the design of different signal processing blocks like pre-select filter, low noise amplifier (LNA) and analog-to-digital (A/D) converter in the receiver front end. The characteristic functions of each of these stages are now dominated by the channel characteristics and it needs to be modified accordingly. This analysis is extended further with the study of frequency offset error and its correction. The unbiased Cramer Rao Lower Bound (CRLB) of estimation error is calculated and supported by computer simulation. The performance of an MB-OFDM system with frequency offset correction in terms of Bit-Error-Rate (BER) is also reported.

基于UWB-PDOA的少基站自适应定位系统研究

超宽带(Ultra-Wideband,UWB)技术在室内外定位中应用广泛,针对传统多基站定位方案的局限性,提出了一种基于超宽带信号到达相位差(Ultra-Wideband Phase Difference of Arrival,UWB-PDOA)的少基站自适应定位系统。该系统利用UWB-PDOA技术和基于ESP32信号强度的权重自适应定位技术,大幅降低了对环境部署的依赖性,提高了定位的精度和稳定性。结合环境先验信息和目标高度的先验知识,构建了先验知识库,采用自适应定位技术,利用多个传感器的信息来调整对不同定位基站的置信度权重,进一步提高了定位精度和鲁棒性。实验结果表明,所提出的系统在视距(Line of Sight,LOS)和非视距(Non Line of Sight,NLOS)环境下都具有较高的定位精度和稳定性,并且仅需要不超过3个基站便可以满足室内环境定位的需求。

Structural Design of High-precision Positioning System in Weak Signal Environment Based on UWB and IMU Fusion

Aiming at the problem that indoor positioning technology based on wireless ultra-wideband pulse technology is susceptible to non-line-of-sight effects and multipath effects in confined spaces and weak signal environments,a high-precision positioning system based on UWB and IMU in a confined environment is designed.The STM32 chip is used as the main control,and the data information of IMU and UWB is fused by the fusion filtering algorithm.Finally,the real-time information of the positioning is transmitted to the host computer and the cloud.The experimental results show that the positioning accuracy and positioning stability of the system have been improved in the non-line-of-sight case of closed environment.The system has high positioning accuracy in a closed environment,and the components used are consumer-grade,which has strong practicability.

融合全局与局部特征的UWB雷达人体动作识别算法

为了消除雷达信号中杂波和噪声对人体动作识别的干扰,提高小样本数据下动作识别的精度,在去除杂波及噪声干扰的基础上,提出一种融合全局与局部特征的超宽带(ultra-wideband,UWB)雷达人体动作识别算法。用动目标指示(moving target indication,MTI)结合自适应中值滤波对雷达原始回波信号进行预处理,再对人体动作的雷达二维特征图像利用主成分分析(principal component analysis,PCA)提取主要分量作为全局特征表征,并用二维离散小波变换(2D discrete wavelet transform,2D-DWT)结合奇异值分解(singular value decomposition,SVD)获取特征图像在不同方向与尺度划分下动作的局部特征表征,并将全局与局部特征进行串联融合;根据融合特征,在网格搜索算法(grid search,GS)优化的支持向量机(support vector machines,SVM)模型中实现人体动作的识别分类。实验结果表明,该算法能有效获取雷达信号中的人体动作信息,平均识别准确率为95.63%,具有良好的识别性能。

A Novel UWB Signal Sampling Method for Localization based on Compressive Sensing

Ultra-wide-band (UWB) signals are suitable for localization, since their high time resolution can provide precise time of arrival (TOA) estimation. However, one major challenge in UWB signal processing is the requirement of high sampling rate which leads to complicated signal processing and expensive hardware. In this paper, we present a novel UWB signal sampling method called UWB signal sampling via temporal sparsity (USSTS). Its sampling rate is much lower than Nyquist rate. Moreover, it is implemented in one step and no extra processing unit is needed. Simulation results show that USSTS can not recover the signal precisely, but for the use in localization, the accuracy of TOA estimation is the same as that in traditional methods. Therefore, USSTS gives a novel and effective solution for the use of UWB signals in localization.

Study of ultra-wideband radar signals-generated technology using two-channel signal generator

Synthesis of ultra-wideband （UWB） linear frequency modulation radar signals is a very important technology for microwave imaging, target identification and detection of low radar-cross-section （RCS） targets. A new method of UWB radar signals generation with two-channel signal generator is presented. The realization structure is given; the principle and errors of signal synthesis are analyzed. At the same time, an automatic .adjustment measure of signal phase is proposed because of phase discontinuity of waveform in this method. The simulation experiment and analysis results indicate that radar signals with large instantaneous bandwidth can be generated by means of this method on the condition that the high-speed digital devices are limited.

High-resolution digital beamforming of UWB signals based on Carathéodory representation for delay compensation and array extrapolation

To realize high-resolution digital beamforming(DBF)of ultra-wideband(UWB) signals, we propose a DBF method based on Carath ′eodory representation for delay compensation and array extrapolation. Delay compensation by Carath ′eodory representation could achieve high interpolation accuracy while using the single channel sampling technique. Array extrapolation by Carath ′eodory representation reformulates and extends each snapshot, consequently extends the aperture of the original uniform linear array(ULA) by several times and provides a better realtime performance than the existing aperture extrapolation utilizing vector extrapolation based on the two dimensional autoregressive(2-D AR) model. The UWB linear frequency modulated(LFM) signal is used for simulation analysis. Simulation results demonstrate that the proposed method is featured by a much higher spatial resolution than traditional DBF methods and lower sidelobes than using Lagrange fractional filters.

HUID:DBN-Based Fingerprint Localization and Tracking System with Hybrid UWB and IMU

High-precision localization technology is attracting widespread attention in harsh indoor environments.In this paper,we present a fingerprint localization and tracking system to estimate the locations of the tag based on a deep belief network(DBN).In this system,we propose using coefficients as fingerprints to combine the ultra-wideband(UWB)and inertial measurement unit(IMU)estimation linearly,termed as a HUID system.In particular,the fingerprints are trained by a DBN and estimated by a radial basis function(RBF).However,UWB-based estimation via a trilateral method is severely affected by the non-line-of-sight(NLoS)problem,which limits the localization precision.To tackle this problem,we adopt the random forest classifier to identify line-of-sight(LoS)and NLoS conditions.Then,we adopt the random forest regressor to mitigate ranging errors based on the identification results for improving UWB localization precision.The experimental results show that the mean square error(MSE)of the localization error for the proposed HUID system reduces by 12.96%,50.16%,and 64.92%compared with that of the existing extended Kalman filter(EKF),single UWB,and single IMU estimation methods,respectively.

基于UWB技术的矿用车辆管理系统

为了解决目前矿用车辆定位过程中动态误差大、定位方向不准确、定位数据丢失等急问题,采用超宽带(UWB)无线载波通信技术,综合对比研究TDOA和TOF 2种时间差进行定位的方法,通过测量信号源与各监测点之间的距离精确的计算出信号源发生的位置。结果表明:当信号源位移速度在大于等于7 m/s的条件下,通过长距离测试验证,其所有信号源最大动态定位误差值均小于7.3 m的AQ 6211—2008标准要求,利用TDOA算法进行测量点与被测量点位置的确定,利用TOF算法进行测量点与被测量点距离的计算,可以有效解决误差、方向及数据等问题。

Impulse Radio UWB Signal Detection Based on Compressed Sensing

The extremely high sampling rate is a challenge for ultra-wideband (UWB) communication. In this paper, we study the compressed sensing (CS) based impulse radio UWB (IR-UWB) signal detection and propose an IR-UWB signal detection algorithm based on compressive sampling matching pursuit (CoSaMP). The proposed algorithm relies on the fact that UWB received signal is sparse in the time domain. The new algorithm can significantly reduce the sampling rate required by the detection and provides a better performance in case of the low signal-to-noise ratio when comparing with the existing matching pursuit (MP) based detection algorithm. Simulation results demonstrate the effectiveness of the proposed algorithm.

Zero-Index Metamaterial Superstrates UWB Antenna for Microwave Imaging Detection

Metamaterials(MTM)can enhance the properties of microwaves and also exceed some limitations of devices used in technical practice.Note that the antenna is the element for realizing a microwave imaging(MWI)system since it is where signal transmission and absorption occur.Ultra-Wideband(UWB)antenna superstrates with MTM elements to ensure the signal transmitted from the antenna reaches the tumor and is absorbed by the same antenna.The lack of conventional head imaging techniques,for instance,Magnetic Resonance Imaging(MRI)and Computerized Tomography(CT)-scan,has been demonstrated in the paper focusing on the point of failure of these techniques for prompt diagnosis and portable systems.Furthermore,the importance ofMWIhas been addressed elaborately to portray its effectiveness and aptness for a primary tumor diagnosis.Other than that,MTM element designs have been discussed thoroughly based on their performances towards the contributions to the better image resolution of MWI with detailed reasonings.This paper proposes the novel design of a Zeroindex Split RingResonator(SRR)MTMelement superstrate with a UWB antenna implemented in MWI systems for detecting tumor.The novel design of the MTM enables the realization of a high gain of a superstrate UWB antenna with the highest gain of 5.70 dB.Besides that,the MTM imitates the conduct of the zeroreflection phase on the resonance frequency,which does not exist.An antenna with an MTM unit is of a 7×4 and 10×5 Zero-index SRR MTM element that acts as a superstrate plane to the antenna.Apart from that,Rogers(RT5880)substrate material is employed to fabricate the designed MTM unit cell,with the following characteristics:0.51mm thickness,the loss tangent of 0.02,as well as the relative permittivity of 2.2,with Computer Simulation Technology(CST)performing the simulation and design.Both MTM unit cells of 7×4 and 10×5 attained 0°with respect to the reflection phase at the 2.70 GHz frequency band.The first design,MTM Antenna Design 1,consists of a 7×4 MTM unit cell that observed a rise of 5.70 dB with a return loss(S11)−20.007 dB at 2.70 GHz frequency.The second design,MTM Antenna Design 2,consists of 10×5 MTM unit cells that recorded a gain of 5.66 dB,having the return loss(S11)−19.734 dB at 2.70 GHz frequency.Comparing these two MTM elements superstrates with the antenna,one can notice that the 7×4 MTM element shape has a low number of the unit cell with high gain and is a better choice than the 10×5 MTM element in realizing MTM element superstrates antenna for MWI.

基于遗传算法的UWB信号非相干捕获方法

本文针对动态信噪比环境超宽带(UWB,Ultra WideBand)信号的非相干捕获,提出了一种基于遗传算法的信号捕获方案.以遗传算法结合在线估计接收信噪比,搜索积分窗口长度与定时位置的参数组合,实现系统要求的比特错误概率.该方法解决了传统捕获方案在未知信噪比条件下积分长度无法择优选取以及捕获门限难于设定的问题.仿真结果表明,基于遗传算法的二维参数捕获方法与传统Look and Jump by Ksteps算法相比有效的提高了未知信噪比条件下的系统捕获性能,拓展了UWB非相干系统的应用范围.

基于非线性光学环镜中SOA的XPM效应生成UWB信号的研究

利用非线性光学环镜(NOLM),提出了一种基于半导体光放大器(SOA)的交叉相位调制(XPM)效应生成超宽带(UWB)信号的方法,设计了系统结构,并进行了仿真实验,得到了中心频率约为6.7GHz、相对带宽约为161%的UWB信号,该信号符合美国联邦通信委员会(FCC)标准,从而验证了该方法的可行性。另外,所生成的UWB信号的中心频率及带宽还具有可调性。

基于动态阈值检测的UWB测距算法

对于高时间分辨率的超宽带(ultra wideband,UWB)信号来说,在测距应用中主要通过估计信号到达时间(time of arrival,TOA)来计算距离。文章提出了一种基于动态阈值检测的TOA估计算法以提高测距精度并降低算法复杂度。对接收方收到的匹配滤波输出脉冲进行峰值检测,确定直达单径(direct path,DP)的检测区间;设定一个能够反映出信号和信道特性的联合度量参数,根据该参数的不同设置相应的最佳阈值因子,在检测区间中通过阈值检测搜索DP精确位置对应的时刻,得到TOA的估计值。仿真采用IEEE802.15.4a标准信道,其结果表明所提算法适用于不同信噪比和延时特性的信道,并兼顾运算复杂度与算法精度。

基于微波光子微分原理的灵活UWB信号产生方法

为了有效克服传统电子信号发生器在工作带宽和工作频率方面存在的电子瓶颈,满足未来光载超宽带系统应用需要,提出了一种光子学超宽带(UWB)信号产生方法。基于微波光子微分的原理,该方法在光域中对高斯脉冲进行灵活处理,进而实现UWB信号的产生。通过理论推导和计算机仿真,对所提方法进行了分析与验证,结果表明,该方法可根据需要实现多种UWB信号波形的产生与调制。此外,通过对系统进行优化配置,还可在输出UWB信号的功率谱中引入一个频率可调的零点,从而避免UWB信号与现有WiFi信号之间的相互干扰。

RBF神经网络辅助的UWB/INS组合导航算法

针对UWB/INS组合导航中由UWB信号中断导致无法对INS进行误差补偿的问题,提出一种径向基神经网络辅助的UWB/INS组合导航算法:当UWB信号可用时,以单独INS解算的位置信息和INS的角速率、比力值信息作为RBF神经网络的输入,以单独INS与UWB/INS组合解算的位置差值作为RBF神经网络的输出进行训练;当UWB信号中断时,利用训练好的RBF神经网络预测INS的位置误差,并对其误差进行校正。实验结果表明:相较于无辅助的UWB/INS组合方法,加入RBF神经网络辅助机制可提高UWB/INS组合导航模型的稳定性及精度。

基于Simulink的Chirp-UWB通信系统综合实验设计

将通信新技术引进教学,设计了我校信息工程专业通信系统综合实验的拓展内容——Chirp-UWB通信系统综合实验。运用Matlab/Simulink构建了ChirpUWB系统仿真模型,实现了二进制正交键控(BOK)调制发送、以及两种接收方案包括匹配滤波器接收和锁相环接收的整个系统仿真,并比较了两种接收方案的性能,给出了在AWGN信道中误码率仿真曲线。实践表明,该综合实验加强了学生对通信系统原理的理解,提高了综合运用所学知识解决实际问题的能力。

Chirp-UWB系统匹配滤波解调接收机的设计与实现

Chirp-UWB通信系统具有低功率谱密度、强抗干扰能力、易同步实现、远距离通信以及高的测距精度等优点,因而获得研究人员的广泛关注和研究。Chirp-UWB通信系统获得这些优良特性的关键之一是接收机采用匹配滤波解调技术实现。利用MATLAB/Simulink仿真平台,对匹配滤波解调的Chirp-BOK UWB通信系统进行了建模,构建的系统模型参数修改方便、实时性强。改变信道参数,能够检验系统在不同信噪比条件下的接收机的解调性能,为接收机硬件电路设计提供理论依据与参考,极大地减少了硬件电路设计和实验过程的盲目性。

基于FPGA的TH-UWB窄脉冲信号发生器设计与实现

给出了一种基于FPGA的TH-UWB窄脉冲信号发生器的实现方法。信号采用脉冲位置调制,调制后的信号利用FPGA片内逻辑门的延时特性,编写延时程序产生携带调制信息的窄脉冲。在AlteraDE2开发平台下实现了全数字化的TH-UWB信号发生器。该发生器系统的信号调制、窄脉冲产生都在FPGA芯片内部进行,与传统模拟发生器相比,可以使整个发生器成本显著降低,易于实现,工作稳定,结构简单且便于系统调试和更改。时序仿真和硬件实测数据表明,所得信号能达到TH-UWB纳秒量级窄脉冲的各项要求。

基于脉冲响应消岐重构的UWB测距优化方法

UWB测距技术因功耗低、安全性高等优势在工业领域应用日益广泛。工业非视距场景下UWB脉冲信号由于穿透衰减和多通道反射等因素,存在首径信号衰减和多径延迟的问题,将会降低系统的定位精度。针对该问题,通过对UWB信号传递及响应建模,提出一种基于UWB信道脉冲响应的消岐重构算法,将信道脉冲簇信号进行泊松过程解析,对代表直线传播距离的首径信号进行特征增强,实现了复杂多径干扰下的首径信号提取与分离,提高了信号到达时间辨识精度,减少了UWB测距误差。进一步地,依据IEEE802015.4a标准对UWB信道响应进行仿真,并实现了不同遮挡环境下的实验研究,仿真和实验结果表明,本文提出的消岐重构算法能够显著提高多干扰环境下的定位精度,在存在多反射源和多遮挡物的工业非视距场景下,可使定位误差相较于传统阈值法降低约79.1%。