多入多出超宽带信道建模与仿真

在IEEE802.15.3a超宽带(UWB)信道模型的基础上,利用平行波近似理论,根据天线阵列的结构和多径的传播方向,提出了一种新的多入多出(MIMO)超宽带统计信道模型。各个子信道的多径幅度、相位和波达时间被引入了信道模型。子信道的信道特征参数满足超宽带信道的特征。实际测量的统计结果表明,波离角(AOD)和波达角(AOA)服从拉普拉斯分布。空间相关性、信道容量和天线间距、角度扩展之间的关系表明,该信道模型满足实际的空间相关统计特性。该模型对MIMOUWB系统的研究具有重要意义。     

基于阵列天线的UWB定位方案研究

为实现简单而精确的定位,提出了一种基于阵列天线的超宽带(ultra wideband, UWB)定位方案。在定位源末端设置4根阵元天线,用于检测未知节点发射的UWB信号,各天线接收的信号经统一的中央处理单元,只需单个定位源就能完成未知节点的三维定位。通过UWB多径信号检测算法进行到达时间差(time difference of arrival, TDOA)估计,无需收发两端时钟同步,且避免了使用复杂的波束赋形技术。同时,提出了一种UWB多径信号检测算法,在分析误差模型对定位精度影响的基础上,以IEEE 802.15.4a信道模型的CM1~CM8为依据,对方案进行了误差性能仿真实验。结果表明,所提方案可实现精确定位,误差达厘米级。     

Single link tracking scheme based on UWB localization

To investigate the low-complex and high-precise tracking method, a novel single link tracking scheme based on UWB localization is proposed. Two antenna arrays are settled at the fixed station (FS) to receive the UWB signal from mobile terminal (MT), one FS is enough for the proposed scheme to track the MT. The UWB multipath detection algorithm for time difference of arrival (TDOA) estimation is presented and TDOA is thus adopted to estimate angle of arrival (AOA), avoiding the synchronization and complicated beamforming for AOA. The impacts of localization errors, concluding multipath and non-line-of-sight (NLOS) errors are simulated for the proposed track scheme. It is demonstrated that the simulation curve can match the real target moving, and the feasibility of the proposed scheme is proved.     

超宽带TH-PPM 调制技术抗干扰性能研究

针对超宽带TH-PPM调制技术在多个频带干扰条件下的抗干扰性能进行了分析研究。基于超宽带TH-PPM调制所使用脉冲波形的不同,推导得出了在多个频带干扰条件下,超宽带TH-PPM调制技术的抗干扰能力指标的通用数学表达式。该结果对单频带干扰也同样适用。此外,在多个频带干扰条件下,对超宽带TH-PPM调制技术、直接序列扩频调制技术和跳频调制技术的抗干扰性能进行了比较分析研究,并分别对其进行了数值仿真。仿真结果表明,在多数情况下,超宽带TH-PPM调制技术抑制多个频带干扰的能力,明显优于直接序列扩频调制技术和跳频调制技术。     

UWB通信系统隐蔽性能仿真分析及系统设计方法

超宽带(UWB)由于其低检测概率(LPD)特性而很有可能成为一种用于战术隐蔽通信的技术.针对两类常用的超宽带无线电信号IR-UWB和MB-OFDM,采用最佳未知信号检测接收机,通过仿真及与直接序列扩频(DSSS)系统比较,评估了超宽带系统的隐蔽性能并提出了提高系统隐蔽性的系统设计方法,剖析了提高IR-UWB通信系统隐蔽性的实现限制.     

On UWB system performance under impulsive noise environment

In this paper, the performance of UWB (ultrawide bandwidth) radio systems under impulsive noise environment (INE) is investigated. At first, the Middleton's class a model is used as a model of impulsive noise (IN), we investigate the statistical characteristics of in-phase and quadrature components of IN, and it is proved that unlike Gaussian noise (GN), they are dependent especially to IN with small impulsive indices, Then, making use of this dependence between in-phase and quadrature components, an ovel UWB radio receiver designed for IN is proposed. The exact expression for the average BER (bit error rate) of this receiver, which is a function of SNR (signal to noise power ratio) and threshold value, is derived. Thirdly, we'll discuss the optimum threshold value. We'll also estimate the performance of UWB radio systems with the proposed receiver designed for IN and with the conventional receiver designed for GN in INE. Numerical results show that the performance achieved by the proposed UWB radio receiver is much etter than that of the conventional UWB radio receiver. Meanwhile, it is shown that both impulsive index and threshold value have much effect on the performance of UWB radio system s under the condition of INE     

Deterministic simulation of UWB indoor propagation channel

A site-specific model of UWB pulse propagation in indoor environment is addressed. The simulation utilizes the principles of geometrical optics （GO） for direct and reflected paths＇ tracing and the time domain technique for describing the transient electromagnetic field reflected from wall, floor, ceiling, and objects. The polarization of the received waveform is determined by taking into account the radiation pattern of the transmitting and receiving antennas, as well as the polarization changes owing to every reflection. The model provides more intrinsical interpretations for UWB pulse propagation in realistic indoor environment.     

新型超宽带脉冲探地雷达接收机的设计与研制

基于等效时间采样原理,提出了一种新型超宽带脉冲探地雷达接收机的设计方法,并研制了实用的超宽带接收机模块,其关键电路包括皮秒级采样脉冲产生电路、肖特基二极管平衡取样门、信号保持与放大电路以及微带魔T结构。该接收机的采样带宽为4 GHz,与理论计算值相一致,采样效率高达40%。实验测试表明,接收机等效采样后重建的基带信号波形与原始微波信号形状吻合度好,证明该接收机具有良好的超宽带特性,满足脉冲探地雷达回波信号接收要求。     

Receiver design of UWB radio systems for an impulsive noise environment

1 .INTRODUCTIONUltrawidebandwidth (UWB )radiosystemshavedrawnalotofattentionduringthelastfew years[1,2 ] .Suchsystems ,basedontimehoppingspread spec trum (THSS)impulseradio (IR ) ,are plannedtoworkinco existencewithotherdigitalsystemsoverabandwidthranging…     

UWB雷达信号设计方法研究

本文首先讨论了高斯白噪声环境下超宽带（ＵＷＢ）雷达信号设计问题，提出了一种自适应最优波形设计方法。这种方法可以集中目标散射回波能量，从而大大提高了接收信号的信噪比；其次，对杂波干扰下的低能量相干目标环境，根据牛曼—皮尔逊准则提出了一种非线性方程牛顿迭代法，与现有的ＵＷＢ信号方法相比，信噪比要改善１０ｄＢ左右。     

毫米波探测器的超宽带耦合特性

探测器是近程探测系统的目标敏感装置, 容易受到电磁脉冲干扰。针对某型毫米波探测器超宽带(ultra-wideband, UWB)电磁脉冲抗扰度不清的实际情况, 围绕UWB辐照环境展开该型探测器的电磁脉冲耦合特性研究。将时域有限积分算法(finite integration technology, FIT)应用于探测器腔体耦合特性研究, 并结合UWB试验系统对探测器开展了辐照试验, 验证了FIT算法的有效性。仿真和试验结果表明, 探测器在竖直状态下的腔体屏蔽效能最差, 仿真试验中其屏蔽效能为20.40 dB; 试验得出探测器的效应场强阈值约为150 kV/m, 在辐照下会出现死机、虚警和硬损伤3种现象, 其中死机现象可通过电源复位恢复, 虚警和硬损伤为不可逆效应现象。     

基于IEEE 802.15.4a信道的超宽带脉冲信号仿真研究

针对超宽带通信技术在远距离、低速率、精确定位方面的应用,对超宽带脉冲信号波形设计和特性进行了研究。采用了优化组合的方法进行了超宽带脉冲信号设计并对其性能进行了研究。通过仿真计算,分析了超宽带脉冲信号在IEEE 802.15.4a信道中的传播特性,得出了信道对脉冲信号影响的相关结论。结果表明,采用优化组合方法设计的超宽带脉冲信号能满足FCC辐射掩蔽标准要求,IEEE802.15.4a信道模型能较好的反映信号传播的基本规律,多路径信道对超宽带信号功率谱影响不大,超宽脉冲带信号具有抗多径干扰能力强的特点,适合低速率无线个域网、精确定位等领域的应用。     

UWB多目标异步定位及算法

基于到达时间法(TOA)和超宽带信息帧往返传输(RTT)原理,提出一种新的UWB多目标异步定位及其算法.系统节点均具有收发功能,在测量某个节点时,往返传输(RTT)的UWB帧只需使用一次,也不需要保证接收节点时钟严格同步的光纤连接等系统条件的限制.与同步方法相比较,本方法和算法具有低复杂性、一般性和实用性.仿真结果也表明其定位精度完全可以与同步TOA法或TDOA法相媲美.     

超宽带无线通信技术的新进展

首先简要介绍了超宽带(UWB)的系统性能特点及UWB的调制与多址接入技术,然后着重讨论了UWB的最新进展,包括:IEEE802.15.3aUWB多径信道模型,UWB的多入多出(MIMO)系统,UWB的正交频分复用(OFDM)系统以及定位于低速无线个域网(LR-WPANs)的802.15.4a标准。最后提出几个值得探索的研究方向,如:寻求一种新的适合分析非正弦窄脉冲的UWB系统的无线通信理论等。     

基于Polycycle信号的UWB正交脉冲序列设计

正交脉冲的产生是超宽带无线应用中的关键技术, 采用Hermite 矩阵特征向量分解方法, 提出了一种基于Polycycle信号的UWB 正交脉冲序列设计方法. 该方法产生的正交成形脉冲功率谱密度分布符合FCC关于室内和室外UWB应用的辐射限制, 有较高的频谱利用率, 脉冲函数自相关性强, 互相关性弱, 利于多址检测. 最后, 分析了2PPM-THMA UWB系统的传输性能, 仿真结果表明正交成形脉冲抗多用户干扰能力优于Scholtz脉冲.     

Optimal design of basic pulse waveforms for THSS UWB radio systems

1.INTRODUCTION Recently,therehasbeenagreatinterestinUWBra dioforfuturehighrateshort rangewirelesscommu nications[1～4].Forhighlyresolvingmultipathand generatingUWBsignalswithrelativelylowcomplexi ty,UWBradiosystemsusuallyuseTHSSimpulse trainwithPPMtocarrydatainformation[5,6].That iswhyitissometimescalledimpulseradio(IR).The essenceofUWBradioisthatitdoesnotuseasinu soidalcarrierbutinsteadcommunicateswithaTHSS basebandsignalcomposedofsubnanosecondpulses withPPM.Thatis,UWBra…     

超宽带合成孔径雷达方程研究

超宽带雷达的相对带宽极大 ,波长变化范围大 ,带内系统特性也会随波长发生变化 ,常规雷达方程已不再适于超宽带雷达。从超宽带雷达天线、UHF/VHF波段接收机噪声温度以及最小可检测的信噪比三个方面研究了超宽带合成孔径雷达方程。修正了超宽带合成孔径雷达方程 ,消除了雷达方程中波长因子的影响 ,为超宽带合成孔径雷达的系统设计奠定了基础。     

基于SPGA算法的低频超宽带 SAR运动补偿方法

对已经初步聚焦的低频超宽带(ultra wideband, UWB)合成孔径雷达(synthetic aperture radar, SAR)图像进行基于图像域的相位误差补偿,可进一步提高图像聚焦质量。依据UWB SAR运动误差模型,提出了基于条带式相位梯度自聚焦（strip phase gradient autofocus, SPGA）算法的相位误差补偿方法。该方法有效地补偿大合成孔径、宽测绘带低频UWB SAR图像中的二维空变相位误差。仿真和实测数据处理结果验证了所提方法的有效性。     

Study on the Generation of Ultra-Wideband (UWB) High Power Microwave

The experimental study of ultra-wideband (UWB) technology, its generation and on-line measurement are presented. An experimental repetitive UWB system is designed, manufactured, and tested. High-pressure spark gap switch and its components, as well as oil spark gap switch are studied experimentally on the system. Experimental results indicate that the system operates at a 200 pps repetitive rate with a stable performance. 100 MW peak power UWB pulses are obtained on the system. Fast-time response capacitive divider is designed and fabricated, allowing for an accurate measurement of the high power UWB signal. The main issues related to the design of the switch and the UWB signal online measurement are discussed.     

一类适用于超宽带无线电的跳时序列族

跳时技术是超宽带无线电实现多址通信的一项关键技术。为保证超宽带无线电的可靠通信并减小系统中用户之间的多址干扰,系统要求跳时序列具有优良的跳时相关性能。基于对二次同余理论的研究,构造了一类适合于超宽带无线电通信系统的跳时序列族,给出了它的构造方法和序列的性质。然后通过对跳时序列相关性能的分析,证明了所得到的跳时序列族具有优良的跳时相关性能,满足跳时异相自相关最大值S_(max)≤2,跳时互相关最大值C_(max)≤4。最后,将该类跳时序列族用于超宽带无线电多用户通信系统进行了误码率性能仿真,仿真结果表明采用该序列族将使系统具有更好的多址性能。