共查询到20条相似文献,搜索用时 15 毫秒
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提出一种基于认知无线电的自适应超宽带窄带干扰抑制方法。基于软频谱思想,利用近似椭球波函数良好的时限-带限特性,设计出一种能够抑制窄带干扰的脉冲波形。通过调整脉冲参数实现对授权频段的动态避让。仿真结果表明:自适应脉冲具有良好的窄带干扰抑制能力,能够自适应地随着感知结果动态地规避授权用户,从而实现UWB系统与其它通信系统的共存。 相似文献
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将最快检测技术应用于超宽带脉冲信号检测中,具体采用改进的CUSUM(Cumulative Sum)算法来检测超宽带脉冲信号。首先分析了经过多径信道衰减后的超宽带脉冲信号概率分布特性,进一步提出了适用于超宽带脉冲信号检测的改进CUSUM算法。理论分析和仿真证明了所提改进算法性能优越且实现复杂度低。该算法克服了块检测算法的信噪比门限效应,且具有最优的检测延迟性能,相同虚警限制下其检测性能明显优于能量检测算法。 相似文献
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针对超宽带频带内授权信号类型确定的特点,为了弥补盒维数检测不能够有效识别信号类型的缺点,提出通过进一步提取信息维数特征对信号调制样式进行识别,该方法融合了盒维数检测和信息维数检测的优点进行合作判决。仿真表明基于信号分形理论的频谱感知能够取得较好的检测效果,且该方法运算复杂度低,对噪声不敏感,能够有效区别噪声与授权信号,抵御模拟授权用户攻击,检测效果优于循环谱检测和能量检测。 相似文献
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超宽带CI脉冲是由多个相干载波合成的窄脉冲信号.该文在此基础上,提出了扩频CI合成窄脉冲技术.由此降低了功率谱密度,提高了频带使用效率和便于多址应用.通过对每个相干载波信号CI扩频且合成,其效果很好.在信道传播上拥有超宽带信号的抗多径高分辨率性能,同时又能对扩频相干副载波进行相关接收,这样大大地提高了相关接收增益,减少了码间串扰.该文运用信号最佳设计方法,将超宽带SSCI信号设计成符合FCC标准和ETSI标准的最佳信号,减少与其他无线系统的相互干扰.文中给出了理论分析、设计方法和计算机模拟仿真结果.该设计方法对于提高UWB通信系统的性能有很重要的意义. 相似文献
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设计了两种小型宽缝结构超宽带天线,一种采用接地CPW馈电方式,另一种采用带状线馈电方式。结果表明这两种天线都有较宽的阻抗带宽。分析了两种天线的特性参数,并比较两种天线的增益和辐射特性,给出两种天线在远区场的脉冲波形比较,并得出不同天线结构对脉冲波形的保真度的影响,这对实际超宽带脉冲天线的设计与应用意义重大。 相似文献
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Ji Wu Wei Wang Qilian Liang Xiaorong Wu Baoju Zhang 《Wireless Communications and Mobile Computing》2014,14(13):1266-1275
In this paper, we propose a new compressive sensing‐based compression and recovery ultra‐wideband (UWB) communication system. Compared with the conventional UWB system, we can jointly estimate the channel and compress the data, which can also simplify the design of hardware. No information about the transmitted signal is required in advance as long as the channel follows autoregressive process. As an application example, real‐world UWB signal is collected and processed to evaluate the performance of our proposed system. The compression procedure is so simple that we just multiply random Gaussian or Bernoulli matrix with the original data to capture all the information we want. Simulation results show that the data could be perfectly recovered if the compression ratio does not exceed 2.5:1 when Bernoulli matrix is chosen as the sensing matrix. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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College of Physics Electronic Engineering the Centre University for Nationalities Beijing China CHE Shu-liang ZHANG Hong-xin LU Ying-hua HE Peng-fei School of Electronic Engineering Beijing University of Posts Telecommunications Beijing China 《中国邮电高校学报(英文版)》2007,14(2):99-102
This study investigates a novel method to numerically generate orthogonal ultrawide band (UWB) shaping pulses based on compressed chirp signal. First, a pulse template with less than 1 ns duration time, which is used to construct a Hermitian matrix, is produced with a compressed chirp pulse. Sub-nanosecond orthogonal pulses are then generated for UWB by using the Hermitian matrix eigenvectors. The simulation results show that the power spectral density distribution of the UWB shaping pulses met the constraint of Federal communications commissions (FCC) spectral mask. The shaping pulses not only have higher spectrum utilization ratio and very short time duration but also have excellent autocorrelation and cross-correlation properties, which is an advantage to reduce the interference between multiusers. Especially, a method to produce sub-nanosecond orthogonal UWB shaping pulses by using a relatively longer duration chirp signal is presented. 相似文献
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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。 相似文献
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从通信干扰角度,基于频域分析方法,针对跳时-脉冲位置调制-超宽带(TH-PPM-UWB)体制,分析了不同噪声干扰信号对通信系统的干扰效果,并运用MATLAB仿真软件,在AWGN信道下,对不同噪声干扰信号的干扰效果进行了蒙特卡洛实验仿真,并对实验结果进行了对比分析,给出了干扰效果(误比特率)与噪声干扰信号功率、带宽和中心频率的关系。为实现对超宽带通信系统干扰的实装研制打下理论基础,具有一定的军事价值。 相似文献
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研究超宽带(UWB,ultra-wideband)的传播特性,是UWB信道理论研究的核心内容。利用Fourier变换对各种超宽带(UWB)脉冲波形的室内反射、透射和绕射进行了研究,并提出了一种新的n阶修正Bessel函数的渐近公式,仿真结果和时域的精确结果对比,一致性吻合较好。 相似文献
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A novel signal separation algorithm based on compressed sensing for wideband spectrum sensing in cognitive radio networks 下载免费PDF全文
In cognitive radio networks, since cognitive terminals use a shared wideband frequency spectrum for data transmissions, they are susceptible to malicious denial‐of‐service attacks, where adversaries try to corrupt communication by actively transmitting interference signals. To address this issue, in this paper, we propose a novel signal separation algorithm based on compressed sensing, which can not only recover the entire spectrum but also separate mixed occupying signals. Specifically, the proposed algorithm is executed following three steps: (i) each cognitive terminal attempts to recover all signals over an entire wideband spectrum employing the compressed sensing technique; (ii) all cognitive terminals send their recovered signals to the fusion center where a wavelet edge detection method is adopted to locate the spectrum edges of these signals and then divide the entire spectrum into several sub‐bands; (iii) the fusion center separates its received signals on each spectrum sub‐band into different categories according to their features. Both analytical and simulation results indicate that this novel compressed‐sensing‐based algorithm can effectively separate wideband signals at a low cost and combat interference of the malicious terminals in cognitive radio networks as well. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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理论上推导了均匀平面波垂直入射与任意入射时的透射系数,利用Fourier变换对各种超宽带(UWB)脉冲波形在室内墙体透射中的失真问题进行了研究,仿真结果和时域的精确结果对比,一致性良好,另外初步分析了波形失真的特性。 相似文献
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UWB(超宽带)技术是继CDMA技术之后迅速发展的一种宽带传输技术,将经过信息调制的基带脉冲进行直接发送,脉冲宽度一般为ns级,因此它的信号能量分布在从DC到几GHz范围。它相对常规窄带传输方式而言有低功率谱、低截获、抗干扰能力强、可高速数据传输、多径分辨能力强和共享频谱等优点。主要介绍了UWB的几种调制技术,包括:TH-PPM、DS-UWB、TH-PAM和TH-OOK。分别阐述了它们的信号调制与解调,并分析比较了它们的性能,得出TH-PPM功率效率最高,是一种最优方案,最后以一种简明方式分析了UWB的应用和未来发展前景。 相似文献
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一种超宽带脉冲发生器的设计与仿真 总被引:2,自引:0,他引:2
利用双极型晶体管的雪崩特性设计了双管并联的超宽带(Ultra-Wideband,UWB)脉冲发生器,通过添加电感使电路的等效负载增加,在维持脉冲宽度基本不变的情况下使输出脉冲的幅度增加到原来的2.5倍。对电路中各元件参数的选取进行详细的分析说明,给出了参数值与脉冲各项性能的关系。仿真得到的UWB脉冲信号幅度为-38.299V,脉冲宽度约为663.265ps,上升时间459.184ps,下降时间约为969.388ps。 相似文献