超宽带信号在高斯噪声中传播性能的研究

超宽带无线通信技术使用微弱的、持续时间极短的脉冲进行短距离通信。超宽带信号具有极宽的射频带宽和较低的中心频率，这种特性可使短距无线通信利用较低的发射功率进行高速传输。根据信号的频谱及其在高斯噪声中的传播性能，研究超宽带信号的减少衰减余量特性，给出不同进制波形的PPM调制超宽带信号比特误码率仿真分析。     

超宽带无线通信与声表面波宽带信号处理技术

介绍了超宽带(UWB)无线通信的技术及特点,与传统窄带无线系统进行了性能比较,指出了超宽带无线通信四大关键技术是:超宽带无线通信脉冲信号的波形设计;超宽带无线通信脉冲信号编码与调制方式;超宽带无线通信信号的检测;超宽带无线通信系统中的同步捕获技术;分析了超宽带尤线通信系统军用的潜在市场,最后阐述了SAW宽带信号处理技术在UWB通信系统中的应用.     

循环功率谱特征检测算法在认知超宽带无线通信的应用

认知超宽带无线通信技术结合了超宽带无线通信技术和认知无线电技术,信号频谱检测是认知超宽带无线通信系统的核心模块之一。循环平稳特性普遍存在于各种调制信号中,该文研究了一种新的检测算法循环功率谱特征检测算法,并以OFDM信号为例给出了软件仿真和性能分析。该检测算法能够区分有用信号,噪声信号和干扰信号,是最适合认知超宽带无线通信系统的。     

超宽带传输体制研究

介绍了超宽带信号的定义和频谱特性。给出了基于超宽带脉冲扩频信号的幅度调制、时延相位调制和伪码复合调制等调制形式和超宽带信号解调方法。对超宽带接收性能进行了相关计算和分析,并给出了接收实现示意框图,及其在无线通信、雷达跟踪、精确定位等方面的应用前景。     

脉冲电磁波传输过程中的失真分析

超宽带通信是近几年发展起来的短距离无线通信技术,而无线通信信道特征取决于信号传播的电磁环境。运用频域法研究大地媒质中的脉冲传播和辐射问题,且在此基础上分析脉冲电磁波穿过3层媒质的失真情况,并分析现代建筑物中的混凝土砖墙对信号传播的影响。通过仿真得到超宽带脉冲信号在传输过程中的失真结果,这对遥感及超宽带通信系统的设计意义重大。     

全数字超宽带系统的关键技术及其发展

介绍了超宽带无线通信系统的技术背景和标准的发展状况，重点阐述了几种基于窄脉冲的数字超宽带系统的体系结构，分析了全数字超宽带系统实现过程中的关键技术，包括脉冲成型、高速模数转换和信号检测与接收技术等，并且探讨了相应的解决方案。     

空时编码技术在超宽带通信系统中的应用

空时编码技术和超宽带技术是当前无线通信领域的热点技术.为了提高短距高速率无线通信的性能,讨论了空时编码技术在超宽带通信系统中的应用方案,由于超宽带脉冲信号具有极窄的时域支撑区,而且信道为密集多径信道,因此超宽带通信系统中的空时编码技术具有完全不同的特性,提出了几种超宽带空时编码方案,并对其性能优缺点进行了分析比较.     

CSS-BOK的匹配滤波接收研究

高速无线通信系统中,Chirp信号作为一种新的超宽带信号,既能实现高速数据传输,又能满足精确定位的要求。借助MATLAB仿真工具,阐述Chirp信号的时频特性以及匹配滤波过程,利用Chirp信号匹配滤波后的压缩特性,对匹配滤波进行仿真。仿真结果显示Chirp信号经匹配滤波器后脉冲宽度被大大压缩,信噪比得到显著提高,与理论分析相吻合。设计了Chirp信号超宽带无线通信系统,仿真得到在AWGN下匹配滤波接收的系统误码率与信噪比关系图,分析了将线性调频扩频CSS（Chirp Spread Spectrum）技术应用到高速无线超宽带通信中的可行性。     

做好UWB管理关键在应用

超宽带通信技术是一种以极低功率在短距离内高速传输数据的新型无线通信技术，业界普遍认为它是下一代短距离（1～100米）无线通信与无线个域网的解决方案之一。近两三年来超宽带技术已成为无线通信领域最热门的研究课题之一，同时也成为短距离高速无线通信协议标准争议的焦点。根据美国联邦通信委员会FCC于2002年的定义，超宽带是指信号的-10dB相对带宽大于20％或-10dB绝对带宽大于500MHz。     

超宽带及其在无线个域网中的应用

近年来,超宽带(UWB)无线通信成为短距离、高速无线网络最热门的物理层技术之一。介绍了超宽带无线通信技术的概念及其信号传输过程中使用的关键技术,包括脉冲成形技术、调制技术以及接收技术,给出了超宽带无线传输系统的基本模型,最后分析了该技术在无线多媒体个域网中的应用。     

Signal design for ultra-wide-band communications in dense multipath

Ultra-wide-band (UWB) wireless communications utilizes information signals characterized by a radiated spectrum with a very wide bandwidth around a relatively low center frequency. We formulate the signal design for binary UWB communications taking into consideration the particular characteristics of UWB propagation in a dense multipath channel.     

基于欠奈奎斯特采样的超宽带信号总体最小二乘重建算法

该文针对超宽带无线通信中需要设计高速模数转换器的问题,提出了一种欠奈奎斯特采样方法,该方法所要求的采样率仅与信号新息率相关,低于奈奎斯特率1个数量级。基于欠采样得到的离散时间超宽带信号,从理论上推导出信号的傅里叶频谱表达式,由此给出了一种总体最小二乘参数估计算法,能够准确地估计出冲激串信号的幅度和时移;通过将估计出的冲激串信号与高斯单脉冲波形卷积,完成超宽带信号的波形重建。仿真和实验结果表明,该文算法能够准确地重建原始超宽带信号,且算法性能优于现有的零化滤波重建算法。     

Ultra-wideband communications: an idea whose time has come

Ultra-wideband (UWB) radio is a fast emerging technology with many unique attractive features that promotes major advances in wireless communications, networking, radar, imaging, and positioning systems. Research in UWB is still in its infancy stages, offering limited resources in handling the challenges facing the UWB communications. Understanding the unique properties and challenges of UWB communications as well as its application in competent signal processing techniques are vital in conquering the obstacles towards developing exciting UWB applications. UWB research and development has to cope with the challenges that limit their performance, capacity, throughput, network flexibility, implementation complexity, and cost. This tutorial focuses on UWB wireless communications at the physical layer. It overviews the state-of-the-art UWB in channel modeling, transmitters, and receivers of UWB radios, and outlines the research directions and challenges that needs to be overcome. Since a signal processing expertise is expected to have major impact in research and development of UWB systems, emphasis is placed on the DSP aspects.     

Some <Emphasis Type="Italic">M</Emphasis>-ary Sequence Designs for Pulse-Based UWB and Other Systems Based on PPM

This paper describes various block waveform encoded (M-ary) signal designs using pulse-position-modulation (PPM) that are useful in pulse-based ultra wideband (UWB) communications in wireless, cable and twisted-pair wire channels, and in other systems based on PPM (not necessarily of UWB nature). This work is focused in four interesting M-ary PPM signal designs: Orthogonal, Equicorrelated, N-orthogonal, and Generic Correlation designs. The designs are based on algebraic constructions with favorable correlation properties, mapping the algebraic constructions into sequences of time shifts to get PPM signals with good correlation properties. For each signal design, the normalized correlation properties are described, the design method is given, and examples of the designs are presented.     

基于高斯脉冲导数的正交UWB波形最优化设计

超宽带无线通信由于其在短距离高速率无线通信中的潜在应用已经引起了广泛的关注.超宽带信号要符合FCC发布的辐射掩蔽,并且要充分利用分配的频谱,这就要求合理的脉冲波形设计.本文分别采用4阶和5阶高斯脉冲导数,进行组合来合成用于UWB通信的脉冲波形,设计中采用归一化有效信号功率作为频谱利用的衡量标准,将波形设计问题转化成为线性规划问题,线性规划问题可以高效地求解,得到的波形具有很高的频谱利用率,并且4阶和5阶高斯脉冲导数合成的脉冲是相互正交的,可以进一步扩大通信的容量.     

An approach to ultrawideband pulse generation and distribution over optical fiber

We propose a novel approach to generating and distributing ultrawideband (UWB) pulse signals over optical fiber. The proposed system consists of a single-wavelength laser source, an electrooptic phase modulator (EOPM), a length of single-mode fiber (SMF), and a photodetector (PD). The combination of the EOPM, the SMF link, and the PD forms an all-optical microwave bandpass filter, which is used to generate a UWB signal with a spectrum meeting the regulation of the Federal Communication Commission. Gaussian doublet pulses are obtained at the receiver front-end, which can provide several gigahertz bandwidths for applications in high-bit-rate UWB wireless communications. Experimental results measured in both temporal and frequency domains are presented.     

Ultra-wideband for multiple access communications

Ultra-wideband wireless communications techniques have many merits, including an extremely simple radio that inherently leads to low-cost design, large processing gain for robust operations in the presence of narrowband interference, covert operations, and fine time resolution for accurate position sensing. However, there are a number of challenges in UWB receiver design, such as capturing multipath energy, intersymbol interference especially in a non-line-of-sight environment, and the need for high-sampling-rate analog-to-digital converters. In this article, we provide a comprehensive review of UWB multiple access and modulation schemes, and their comparison with narrowband radios. We also outline the issues with UWB signal reception and detection, and explore various suboptimal low-complexity receiving schemes     

On the coexistence of power-controlled ultrawide-band systems with UMTS, GPS, DCS1800, and fixed wireless systems

Ultrawide bandwidth (UWB) wireless technology will play a key role in short-range wireless connectivity supporting very high bit rates availability, low power consumption, and location capabilities. UWB can be conveniently deployed in the design of wireless local and personal area networks, providing advanced integrated multimedia services to nomadic users within hot-spot areas. The very large bandwidth required by the UWB signals cannot be exclusively allocated; thus, UWB band overlaps with the bands allocated to many other narrow-band systems. Therefore, the assessment of the interference caused by UWB devices on already-existing systems is of primary importance to ensure coexistence and, therefore, to guarantee acceptance of UWB technology worldwide. We study the coexistence issues between an UWB-based system and universal mobile telecommunication systems, global positioning systems, DCS1800, and fixed wireless access systems and point-to-point (PP) links terminals. UWB interference is evaluated accounting for the UWB signal model, a realistic UWB master/slave system architecture with power-controlled terminals. Furthermore, we analyze the dependence of the UWB interference from the UWB signal parameters and demonstrate through computer simulation that, in all practical cases, a UWB system can coexist with the selected victim terminals without causing any dangerous interference.     

Adapting the Ranging Algorithm to the Positioning Technique in UWB Sensor Networks

Ultra-Wideband (UWB) is an emerging technology for short-range wireless communications. Due to the high bandwidth of UWB signals, accurate ranging and positioning is possible, which is one of many reasons why UWB is a candidate physical layer for another emerging research area, that of wireless sensor networks (WSNs). In this work, we argue that the ranging algorithm design should be made with the characteristics of the positioning algorithm in mind. In considering ranging and positioning in parallel, we are able to construct a range estimator that is tailored to the positioning algorithm, thereby achieving robustness to non-line-of-sight (NLOS) effects, reasonable overall complexity, and good performance in terms of positioning error. The analysis and simulations in this work are based on the channel models adopted by the IEEE 802.15.4a working group, and highlight the benefits and drawbacks of the proposed approach.     

基于聚焦矩阵的超宽带信号DOA估计

超宽带(UWB-Ultra Wide Bandwidth)通信技术是无线通信中的一个非常有发展前途的技术.基于频域模型的UWB到达角估计方法只能解决非相干源问题,因此提出了一种改进的估计方法.该方法通过构造聚焦矩阵来估计相干源问题.仿真结果表明,该方法有效易行.