基于Hermite函数的超宽带脉冲波形设计与性能分析

根据联邦通信委员会关于超宽带辐射功率谱的限制以及适用于多址方式的窄脉冲要求,设计了一组基于Hermite函数的超宽带脉冲波形。所设计的脉冲波形具有正交性和不随阶数变化的恒定脉宽两个重要特性,从而提供了良好的防时间抖动性能并有效降低符号间干扰;为了评估相关接收机的性能,对设计脉冲信号的自相关和互相关函数的闭合表达式进行了推导;分析了跳时脉位调制超宽带系统中脉冲波形在加性高斯白噪声、多址干扰、多径衰落信道等多种环境下的误码率性能,探讨了时间抖动对系统性能的影响,并将仿真结果与高斯单周期脉冲进行比较。分析结果表明该脉冲设计方案提供了一种灵活而系统的超宽带脉冲设计方法,所设计脉冲既满足辐射功率谱限制又提供良好的系统误码性能。     

Performance Evaluation of UWB Systems Exploiting Orthonormal Pulses

The novel pulses, which not only meet the power spectral mask of the Federal Communications Commission (FCC) but also preserve orthonormality at the correlation receiver, have been proposed by Kim for high data rate communications in indoor ultra-wideband (UWB) systems. The proposed multiple orthonormal pulses comply with the FCC spectral mask without additional frequency shifting or bandpass filters, and furthermore, provide enhanced bit-error rate (BER) performance, compared with a well-known Gaussian monocycle and modified Hermite pulses. This paper analyzes the impact of the proposed pulses' properties, such as their auto- and cross-correlations, on the correlation receiver of the UWB system based on the pulse position modulation. The performance of the proposed pulses are compared with different waveforms under various conditions, such as multipath fading, timing mismatch, and multiuser interference. We also discuss a modulation scheme using the multiple orthogonal pulses to achieve the enhancement of data rate and the impact of the correlation characteristics of the proposed waveforms on the BER performance. Simulation results demonstrate the effectiveness of the proposed orthonormal pulses in various conditions, comparing with different waveforms     

基于光注入半导体激光器的超宽带信号产生

提出一种基于光脉冲注入条件下半导体激光器腔 内交叉增益调制(XGM)效应的超宽带(UWB)信号产生方案,通过一个增益开关激光器(ML)、 一个半导体激光器(SL)和一个光带通滤波器(OBPF),在平衡探 测器(BPD)端口直接检测输出重复频率为2.5GHz的UWB一阶微分(Mo nocycle)和二阶微分(Doublet)信号, 而且通过引入马赫-曾德尔调制器(MZM),还可对产生的UWB信号实现开关键控(OOK)。 对所提系统 进行了全面的系统仿真分析,并进行了实验验证,实现了上述各种条件的UWB信号产生,并 实现了UWB信 号的40km光纤传输实验。实验结果表明:该方案获得的UWB信号的频 谱与美国联邦通信委员会(FCC)定制的EIRP标准吻合,同时经过调制的 UWB信号的波形经40km光纤传输之后基本保持不变。为了证明本文方 法产生的UWB信号的重复变化特点,还产生了频率为3.75GHz的UWB信 号。     

Multiple ultra-wideband signal sources exploiting XPM in SFRL

A novel scheme for all-optical broadcast ultra-wideband (UWB) monocycle pulses generation based on cross-phase modulation (XPM) in semiconductor fiber ring laser (SFRL) is proposed, in which three UWB positive or negative monocycle pulses can be generated simultaneously. A comprehensive broad-band dynamic model for this kind of all-optical broadcast UWB monocycle sources is established, which is further applied to numerically analyze the impacts of injection current of semiconductor optical amplifier (SOA), the power and wavelength of the signal light on the performance of the UWB positive monocycle pulses with higher power spectral density. The results show that the spectra of the UWB positive and negative monocycle pulses generated by this scheme match the Federal Communications Commission (FCC) definition quite well. Three UWB positive monocycle pulses with better performance can be obtained when the power of signal light is at a high level, and three other UWB positive monocycle pulses with good tolerance to both the injection current of the SOA and the wavelength of the signal light can be obtained. In addition, the powers of the lasing light coupled into the SFRL should not be strong to obtain three UWB positive monocycle pulses with better performance.     

Comparisons of various pulse shapes for DS-UWB signals over the UWB channel

In this paper, we first investigate the power spectral densities (PSD) of bipolar modulated Direct Sequence Ultra Wide Band (DS-UWB) signals using various pulse shapes under the FCC UWB emission mask. Considered pulse shapes are the first five derivatives of the Gauss pulse (p₁, p₂, p₃, p₄ and p₅), the first four orthogonal modified Hermite waveforms, and Daubechies wavelets (db-q). It is observed in the PSD results that p₄ and p₅ Gauss pulses, the Daubechies (db-q) for q>4 comply with the FCC UWB rule by selecting proper values for the pulse duration. Then, we derive the pulse shape dependent probability of error expression for bipolar DS-UWB signals over the standard UWB channel. The five pulse shapes (p₄, p₅, db-5, db-6 and db-7) complying with the FCC emission mask are numerically compared by using the derived probability of error expression over the CM1 model of the Standard UWB channel. Results reveal that the Daubechies have better performance than those of the two Gauss pulses.     

基于Polycycle信号的干扰抑制UWB自适应脉冲设计

 针对认知超宽带与现存窄带系统干扰问题,采用Polycycle信号作为超宽带原始脉冲,使用Hermite矩阵特征向量方法设计了认知超宽带自适应脉冲,实现了干扰抑制.仿真结果表明,提出的自适应脉冲功率谱密度分布符合FCC室内和室外频谱规范,实现了自适应频段陷波.基于PAM-TH UWB系统性能分析表明自适应脉冲具有较强的多用户干扰和窄带干扰抑制能力.     

窄带干扰抑制的一种新型频率编码正交UWB脉冲设计

文中提出一种基于正交载波和伪随机序列的新型频谱编码正交UWB脉冲设计方法，该方法是在频域中利用PN序列对经过频移的子脉冲进行编码来产生正交脉冲．在IR-UWB（脉冲无线电超宽带）中引入了正交载波和PN序列，使其不仅具有传统IR—UWB和多频带CB-UWB（基于载波的超宽带）优点，而且提高了UWB信号发射的瞬时频谱和瞬时能量的效率．脉冲的自相关和互相关特性皆优于传统的脉冲。另外，借助于认知无线电技术，可保证发送信号满足FCC的UWB频谱规划，避免与其他传统窄带系统干扰。仿真结果表明该脉冲设计方法能够有效的抑制窄带干扰，并降低复杂度。     

A novel ultra-wideband pulse design algorithm

We present a new algorithm to numerically generate pulses that not only have a short time duration for multiple access, but also meet the power spectral constraint of Federal Communications Commission (FCC) ultra-wideband (UWB) mask. In fact, applying our algorithm to the FCC spectral mask for UWB systems can lead to the design of multiple orthogonal pulses that are compliant. Our algorithm presents a flexible and systematic method for generating UWB pulses that have many advantages over the Gaussian monocycle pulse.     

Orthonormal pulses for high data rate communications in indoor UWB systems

In this letter, we propose novel pulses which not only meet the power spectral mask of the Federal Communications Commission (FCC) for indoor Ultra-wideband (UWB) systems but also preserve orthogonality at the correlation receiver. The proposed pulses are derived from a parametric closed-form solution. Thus, multiple orthonormal pulses that comply with the FCC mask without additional frequency shifting or bandpass filters can be generated for high data rate communications or multiple access schemes. Simulation results demonstrate that high data rate communication is achieved by the proposed orthonormal pulses via pulse shape modulation and pulse position modulation.     

UWB pulse design using constraint convex sets method

In this paper, we propose a constrained convex sets–based method for designing ultra‐wideband (UWB) pulse. The UWB pulses designed using earlier proposed methods either do not fit well in UWB spectral mask or require extra processing circuitry for pulses to fit in the UWB spectral mask. The proposed constraint sets–based method is flexible and optimum for the UWB mask. The pulse designed by the proposed method is Federal Communication Commission compliant and has an autocorrelation function similar to the Gaussian pulse. The bit error rate performance of time hopping binary phase shift keying using the proposed method and some of the existing methods such as Norman and Lee pulses and sixth derivative Gaussian pulse is analyzed in additive white Gaussian noise and Saleh‐Valenzuela channels. Pulse designed using the proposed method outperforms existing pulse design, and the same is verified through simulations. The proposed algorithm is flexible and can also be used to mitigate narrow band interference, multiband UWB pulse generation and any other Federal Communication Commission (or other regulatory body) compliant spectrum mask by modifying the parameter of the proposed constraint set(s).     

A CMOS UWB Pulse Generator for 6–10 GHz Applications

A CMOS ultra wideband (UWB) pulse generator with low energy dissipation and high peak amplitude is presented for 6–10 GHz applications. The pulse generator complies with the FCC spectral mask for indoor UWB systems. It consists of a glitch generator, a pulsed oscillator, and a pulse shaping filter. The pulsed oscillator is switched on by the glitch signal only for a short duration, so as to make a UWB pulse. For sub-nanosecond pulse generation, a pulsed oscillator with fast transient response is proposed. A pulse shaping filter makes the oscillator output fall into the FCC spectral mask. The pulse generator is fabricated using a 0.18 $mu$ m CMOS process. The core chip has a size of 0.11 mm $^{2}$. It shows pulse duration of about 500 ps with ${-}10$ dB bandwidth of 4.5 GHz from 5.9 to 10.4 GHz. The energy consumption is 27.6 pJ per pulse with a peak-to-peak amplitude of 673 mV on a 50 $Omega$ output load. The generated pulses are very coherent with 1.8 ps RMS jitter.      

A 750 Mb/s, 12 pJ/b, 6-to-10 GHz CMOS IR-UWB Transmitter With Embedded On-Chip Antenna

This paper presents a novel impulse radio based ultra-wideband transmitter. The transmitter is designed in 0.18 mum CMOS process realizing extremely low complexity and low power. It exploits the 6-to-10 GHz band to generate short duration bi-phase modulated UWB pulses with a center frequency of 8 GHz. No additional RF filtering circuits are required since the pulse generator circuit itself has the functionality of pulse shaping. Generated pulses comply with the FCC spectral emission mask. Measured results show that the transmitter consumes 12 pJ/b to achieve a maximum pulse repetition rate of 750 Mb/s. An optional embedded on-chip antenna and a power amplifier operating in 6-10 GHz band are also designed and investigated as a future low cost solution for very short distance IR-UWB communications.     

基于正交脉冲波形的高速超宽带通信系统

提出了基于小波函数的两个正交脉冲,其功率谱密度满足美国通信委员会(FCC)对UWB系统的频谱限制。在此基础上提出了使用脉冲波形的极性调制和正交脉冲波形的形状调制相结合的一种高速超宽带通信系统,可以同时传送多个比特信息提高传信率。     

Pulse shaping for high data rate ultra‐wideband wireless transmission under the Russian spectral emission mask

This paper addresses impulse‐radio ultra‐wideband (IR‐UWB) transmission under the Russian spectral emission mask for unlicensed UWB radio communications. Four pulse shapes are proposed and their bit error rate (BER) performance is both estimated analytically and evaluated experimentally. Well‐known shapes such as the Gaussian, root‐raised cosine, hyperbolic secant, and the frequency B‐spline wavelet are used to form linear combinations of component pulses, shaped to make efficient use of the spectral emission mask. Analytical BER values are derived using a Nakagami‐m model, and good agreement is found with the experimentally obtained BER. The proposed pulse shapes allow IR‐UWB transmission with BERs below the limit for a 7% overhead forward error correction, achieving distances of up to 6.5 m at 1 Gbit/s, 4.5 m at 1.25 Gbit/s, and 1 m at  Gbit/s. These results confirm the viability of IR‐UWB transmission under the strict regulations of the Russian spectral emission mask.     

基于SOA增益饱和效应生成UWB信号的研究

光纤传输超宽带信号(UWB over fiber)的提出解决了UWB传输距离短的问题,成为国内外研究的热点课题,如何在光域中生成UWB是该系统的关键技术之一。对称形UWB(doublet)与常用的单周期高斯脉冲信号(monocycle)相比,在低频部分的功率谱密度较低,在UWB系统中有更好的性能。为此提出了利用半导体光放大器(SOA)的增益饱和效应生成对称形UWB信号的方法,并进行了仿真实验,得到了符合美国联邦通信委员会(FCC)标准的中心频率为8.3GHz,相对带宽约为142%的对称形UWB信号,验证了该方法的可行性。     

基于SOA的交叉相位调制生成UWB信号的研究

超宽带信号(UWB)的光学生成技术是光载超宽带通信系统(UWB-over-fiber)的关键技术,半导体光放大器(SOA)的非线性特征在全光信号处理中有着广泛的应用。提出基于SOA的交叉相位调制(XPM)效应的UWB的光学生成方法。该方法首先利用SOA的XPM实现高功率的高斯泵浦光和低功率的直流探测光的XPM,然后利用光学滤波器对探测光进行鉴频,实现相位调制到强度调制的转换,从而获得单周期UWB信号。提出了采用光带通滤波器和波分复用器对探测光进行鉴频的两种方法,获得中心频率分别为5.15GHz和5.05GHz,相对带宽分别为150%和149%的UWB信号,符合FCC标准。     

A Fully Differential Digital CMOS UWB Pulse Generator

A new fully digital CMOS pulse generator for impulse radio ultra-wideband (UWB) systems is presented. First, the shape of the pulse which best fits the FCC regulation in the 3.1–5 GHz sub-band of the entire 3.1–10.6 GHz UWB bandwidth is derived and approximated using rectangular digital pulses. In particular, the number and the width of pulses that approximate an ideal template are found through an ad hoc optimization methodology. Then a fully differential digital CMOS circuit that synthesizes the pulse sequence is conceived and its functionality demonstrated through post-layout simulations. The results show a very good agreement with the FCC requirements and a low power consumption.     

基于遗传算法的超宽带波形设计

采用遗传算法(GA)进行了一种新颖的超宽带(UWB)脉冲波形的设计。从多带Chirp信号出发,将波形设计问题转化成有约束条件的逼近问题求解,然后通过遗传算法解决逼近问题。得到的波形不仅满足联邦通讯委员会(FCC)的频谱模板,而且具有88%的频谱利用率。仿真结果验证了采用遗传算法的波形设计具有低时间复杂度;提出的UWB脉冲波形具有较高的频谱利用率,优于其他的UWB脉冲例如B样条脉冲。     

基于SOA-XGM的对称型UWB信号光学产生的研究

文章提出了两种利用SOA(半导体光放大器)的XGM(交叉增益调制)和FBG(光纤布拉格光栅)光学生成对称型UWB(超宽带)信号的新方法.分析了该方法的工作原理并进行了仿真实验,分别得到了符合FCC(美国联邦通信委员会)标准的中心频率为5.35 GHz、相对带宽为114％以及中心频率为4.7 GHz、相对带宽为132％的...     

A Single Transistor‐Level Direct‐Conversion Mixer for Low‐Voltage Low‐Power Multi‐band Radios

A CMOS direct‐conversion mixer with a single transistor‐level topology is proposed in this paper. Since the single transistor‐level topology needs smaller supply voltage than the conventional Gilbert‐cell topology, the proposed mixer structure is suitable for a low power and highly integrated RF system‐on‐a‐chip (SoC). The proposed direct‐conversion mixer is designed for the multi‐band ultra‐wideband (UWB) system covering from 3 to 7 GHz. The conversion gain and input P1dB of the mixer are about 3 dB and ?10 dBm, respectively, with multi‐band RF signals. The mixer consumes 4.3 mA under a 1.8 V supply voltage.