基于Chirp脉冲压缩技术的超宽带通信系统设计

研究了线性调频(Chirp)信号的频谱结构,设计了线性调频调制的超宽带无线通信系统,并对该系统的各点波形和传输特性进行了仿真.结果表明Chirp信号的频谱能很好满足FCC对UWB辐射掩蔽的限制,信号具有较高的频谱利用率.在满足一定误码率的情况下,信号传输距离可达到900m.     

基于Delta算子的超宽带脉冲波形设计方法

从FCC频谱模板出发,提出一种超宽带脉冲信号的设计方法,引入Delta算子理论使经光电导开关产生的信号能够利用连续系统设计法进行处理.该方法避免了传统数字信号处理中的系数表达精度不够及高采样率情况下的数值不稳定,适用于不同的频谱模板.在理论分析的基础上对方法进行了阐述和模拟仿真,仿真结果验证了该超宽带脉冲信号波形设计方法的有效性.     

满足FCC频谱限制的UWB脉冲设计算法研究

在超宽带通信系统中,满足FCC频谱限制的UWB脉冲波形设计是一个研究的热点.首先对高斯脉冲及其导函数的频谱形式进行理论推导及仿真实现,在此基础上提出了两种满足FCC频谱限制的UWB脉冲波形算法,并比较了各自的优缺点.     

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.     

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。     

一种高频谱利用率的PSWF脉冲组设计

脉冲超宽带(Impulse Radio Ultra-wideband,IR-UWB)技术主要使用脉冲传输信息,脉冲波形的选择影响着整个系统的性能。椭圆球面波函数(Prolate Spheroidal Wave Function,PSWF)脉冲具有频谱灵活可控的特点,在超宽带(Ultra-wideband,UWB)系统中得到了广泛应用。介绍了PSWF的定义和求解算法,针对目前存在的PSWF脉冲组频谱利用率较低的问题,提出了一种高频谱利用率的多频带正交PSWF脉冲组设计方法。仿真结果表明,该方法在满足FCC频谱掩膜条件的同时,有效地提高了PSWF脉冲组的频谱利用率,从而增加了接收端的信噪比。     

UWB信号光纤传输性能分析

该文分析了超宽带(UWB)信号光纤传输的性能,分析对比了电UWBmonocycle和doublet信号经过光强度调制后光纤传输的性能,介绍了两种光生UWBmonocycle脉冲的方法,分析了这两种方法产生的信号经光纤传输后的时域波形与频谱。研究结果对实际的UWBover fiber系统应用具有指导意义。     

一种新颖的UWB成形脉冲算法

超宽带（UWB）通信系统利用优化成形脉冲方法，可以产生符合美国联邦通信委员会（FCC）制订的辐射限值的发射信号。此方法在数学表达上简单、清晰。仿真结果表明，该方法可以使UWB成形脉冲的功率谱在高、低频带都能逼近FCC的标准辐射值，得到的组合系数表达简单。在硬件实现时能够减少寄存器数量和提高运算速度。     

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。     

利用光反馈半导体激光器产生超宽带混沌脉冲信号

提出了一种基于光反馈半导体激光器的混沌特性产生超宽带(UWB)信号的新方法。一个商用的通信波段半导体激光器在外腔光反馈下实现混沌振荡,输出连续波混沌激光,经由一个电吸收调制器后,被调制为一系列混沌脉冲信号。该混沌脉冲信号的频谱特性可通过调节半导体激光器的偏置电流和反馈强度进行控制。实验分别获得了中心频率为4.0 GHz、相对带宽为181%和214%的混沌脉冲UWB信号。进一步数值仿真了偏置电流和反馈系数对混沌脉冲UWB信号频谱特性的影响,实验结果与模拟验证相符。该方法实验装置简单,UWB信号频谱特性易控,可用作未来UWB光纤无线通信系统的光生微波信号发生装置。     

一种新的超宽带脉冲波形设计方法

首先介绍了UWB成形脉冲的算法,然后基于Hermite矩阵和Chirp信号得到了UWB的成形脉冲。在对Chirp脉冲的带宽、中心频率等性能参数比较分析的基础上,将若干个Chirp脉冲信号进行线性叠加,通过仿真结果表明,随之产生的脉冲信号不仅满足FCC对UWB脉冲信号辐射功率要求,而且其脉冲信号的频谱利用率也很高,同时还能有效抑制对其他窄带系统的干扰。     

A fully integrated low power PAM multi-channel UWB transmitter

A new transmitter for ultra-wideband (UWB) impulse radio is described in this paper. The new UWB transmitter implements a low power Gaussian shaping filter to reduce the side-lobe in the frequency domain. A simple pulse amplitude modulation (PAM) circuit is used to keep the power consumption low. The proposed architecture features the simple design, low-power operation, and enables the pulse-shape generation for a multi-channel UWB. The core layout size is only 0.2 mm². The simulation results show that the generated signals satisfy the FCC spectrum mask, and the average power consumption is <1.97 mW for the 1.8 V supply voltage. Pulses are transmitted at a PRF (pulse repetition frequency) of 40.5 MHz in 500 MHz bandwidth channels equally spaced within the 3.1–10.6 GHz UWB. This transmitter is designed and fabricated in a 0.18-μm CMOS process.     

一种新的UWB脉冲成形方案

本文基于美国联邦通讯委员会FCC对UWB信号的发射功率谱强制规定,提出了一种新的UWB脉冲成形方法-Gaussian-sinc函数波形脉冲.该方法通过方便灵活的参数调整,可以产生完全符合FCC频谱模板要求的极窄脉冲波形.仿真结果表明,该方法产生的UWB系统发射脉冲旁瓣小,频谱利用率高,不需降低整个频段的信号发射功率,就能有效解决共存通信环境下的同频干扰问题.     

Ultra-Wideband Waveform Generator Based on Optical Pulse-Shaping and FBG Tuning

We propose and demonstrate experimentally a prototype for ultra-wideband (UWB) waveform generator based on optical pulse shaping. The time-domain pulse shape is written in the frequency domain, and a single-mode fiber performs frequency-to-time conversion. A U.S. Federal Communications Commission (FCC)-compliant power efficient pulse shape is inscribed in the frequency domain by a fiber Bragg grating (FBG) with an excellent match between optimized and measured pulses. Two other popular UWB pulse shapes (Gaussian monocycle and doublet pulses) are achieved by proper tuning of two FBG-based variable optical filters. A balanced photodetector removes an unwanted rectangular pulse superimposed on the desired waveform, assuring compliance at low frequency.     

基于频域分析的UWB系统与GSM兼容性研究

通过频域的方法对UWB的信号进行分析,可以看到它们的功率谱中都存在着离散谱线.通过仿真分析表明,由于离散谱线导致了UWB功率谱的不平坦,使得UWB对不同中心频点的GSM信号的抗干扰能力差别很大,适当地对UWB所传输的数据和扩频码进行编码和优化可以平滑其功率谱线,从而提高UWB对GSM的抗干扰性能.     

Novel Spectrally Efficient UWB Pulses Using Zinc and Frequency‐Domain Walsh Basis Functions

In this paper, two sets of spectrally efficient ultra‐wideband (UWB) pulses using zinc and frequency‐domain Walsh basis functions are proposed. These signals comply with the Federal Communications Commission (FCC) regulations for UWB indoor communications within the stipulated bandwidth of 3.1 GHz to 10.6 GHz. They also demonstrate high energy spectral efficiency by conforming more closely to the FCC mask than other UWB signals described in the literature. The performance of these pulses under various modulation techniques is discussed in this paper, and the proposed pulses are compared with Gaussian monocycles in terms of spectral efficiency, autocorrelation, crosscorrelation, and bit error rate performance.     

Pulse shape optimization for physical layer UWB communication and performance evaluation in Saleh–Valenzuela channel IEEE 802.15.3a

Ultra-Wideband communication faces constraints on radiated power from regulatory bodies to minimize the co-existing interference with the narrowband communication. These limitations cause sacrifices in terms of data rate. In this paper, a new methodology of pulse shaping is proposed to meet the spectrum mask given by Federal Communication Commission (FCC). This methodology acutely reduces the undesired ringing effect in the time domain which in turn reduces the required power per unit bandwidth of the signal. We select 7th order derivative of Gaussian monocycle as a base pulse and modulate this pulse with Gaussian window in the time domain to achieve the proposed pulse shape. The power spectral density (PSD) of the proposed pulse is perfectly fitted for spectral mask provided by FCC, in comparison of PSD of the base pulse, which in turn simultaneously provides better antenna power resolution due to the reduced ringing effect in the time domain for the proposed pulse. We also analyse the behaviour of the pulse in multi-user Time Hopped (TH) UWB environment for Saleh Valenzuela IEEE 802.15.3a multipath fading channel to find the suitability of the pulse for UWB communication.     

Generation of Power-Efficient FCC-Compliant UWB Waveforms Using FBGs: Analysis and Experiment

In this paper, we design, analyze, and demonstrate experimentally U.S. Federal Communications Commission (FCC)- compliant power-efficient ultrawideband (UWB) waveforms generated by optical pulse shaping. The time-domain pulse shape is written in the frequency domain, and a single-mode fiber performs the frequency-to-time conversion. The waveform is inscribed in the frequency domain by the fiber Bragg grating (FBG). A significant challenge for this approach is elimination of an unwanted, positive rectangular pulse superimposed on the desired waveform. Our innovative use of balanced photodetection eliminates this pedestal, assuring compliance with the FCC mask at low frequency. Three UWB pulses with duration of 0.3,0.6, and 1.2 ns are designed and tested experimentally. Whereas an excellent match between the optimized and measured pulses is achieved for the simpler, shorter duration waveforms, the noise in the fabrication process of FBGs limits the generation of the more complex, longer duration waveforms.