共查询到20条相似文献,搜索用时 125 毫秒
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超宽带无线信道的频率依赖特性直接影响到超宽带接收机的设计和以脉冲波形为基础的多址技术。本文针对频率依赖特性对超宽带脉冲信号波形产生的影响,分别从相位谱和幅度谱两个方面分析超宽带脉冲信号的相位失真和幅频失真特性,建立了描述脉冲波形失真特性的数学模型。使用该模型对高斯二阶导数脉冲信号的波形失真进行仿真分析,得到了只发生相位响应失真、只发生幅度响应失真、以及同时发生相位—幅度响应失真的脉冲波形。 相似文献
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文章介绍了超宽带脉冲信号的产生、信号调制及其功率谱,讨论了高斯脉冲信号的波形,分析了几种脉冲位置调制的特性,介绍了超宽带信号仿真原理,并从性能和实用性方面进行了讨论和比较,对存在的问题进行了研究。 相似文献
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激光高度计接收脉冲回波是叠加有噪声的多重非高斯波形,有效提取非高斯波形的统计参量对于反演目标高度和种类信息是十分关键的。基于接收脉冲回波信号的特点,利用广义高斯函数模型完成接收脉冲回波信号的数学建模。通过对接收脉冲回波的平滑滤波和初始参数获取,并采用非线性最小二乘算法,开发了一种提取接收脉冲回波统计参量的波形分析器。利用波形分析器对仿真的回波波形进行了处理,结果表明,对于15 dB的单个广义高斯波形,其统计参量的最大提取误差不超过1%。随着广义高斯分量个数的增加以及回波信噪比的降低,统计参量的提取误差有所增加。利用波形分析器能够有效地提取回波波形的统计参量,为反演目标信息提供数据依据。 相似文献
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文章介绍了UWB脉冲设计所遵循的要求,分析了传统UWB脉冲的波形特征,指出了其不足,并对结果进行了仿真.然后介绍了一种新的PSWF脉冲波形设计方法,并分析了其不仅满足FCC对UWB脉冲的规定,而且克服了高斯脉冲波形不满足正交性的缺点. 相似文献
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基于小波分析的脉冲信号波形检测方法 总被引:1,自引:0,他引:1
通过对多种小波函数的分析、比较,提出了一种基于小波分析的脉冲信号时域波形检测方法,该方法利用小波变换模的极大值特性,较好地实现了对脉冲成形信号波形参数的检测。理论分析和仿真研究结果表明,该方法对高斯噪声信道具有较强的适应能力,并且算法简单、运算量小、信号参数检测精度高,具有较好的工程应用前景。 相似文献
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首先分析了在超宽带系统中高斯脉冲成形因子和微分阶数对其能量谱密度的影响,并在此基础上,为了提高高斯脉冲波形的频谱利用率,采用高斯导函数线性组合来产生脉冲波形,提出并分析了一种基于粒子群(PSO)优化算法的超宽带无线脉冲波形优化设计方法,仿真表明该方法产生的高斯导函数线性组合脉冲能够很好地满足FCC的频谱掩模限制。 相似文献
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An ultra-wide-band (UWB) signal is characterized by a radiated spectrum with a very wide bandwidth around a relatively low center frequency. In this paper, we study the reduced fading margin property of UWB signals. To evaluate the fading margin, we compare the performance of UWB signals in an environment with only additive white Gaussian noise (AWGN) versus the performance of UWB signals in a dense multipath environment with AWGN. The assumption here is that the presence of multipath causes a small increase in the signal-to-noise ratio required to achieve reasonable levels of bit error rate. A numerical example confirms this assumption, more specifically, the example shows that to achieve a bit error rate equal to 10-5, we require about 13.5 dB in the AWGN case and about 15 dB in the multipath case, resulting in a fading margin of just 1.5 dB. This small fading margin can be understood by the ability of the UWB signal to resolve the dense multipath 相似文献
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在加性高斯白噪声信道和多用户干扰条件下,介绍了DS-PAM UWB信号及基于高斯近似法的DS-PAM UWB系统的多址接入误比特率公式,然后分析了影响DS-PAM UWB系统多址接入性能的因素.结果表明,随着用户比特速率和接入用户数的增加,系统的误比特率也增加,而增大重复码长度可降低系统误比特率. 相似文献
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On the UWB system coexistence with GSM900, UMTS/WCDMA, and GPS 总被引:14,自引:0,他引:14
Hamalainen M. Hovinen V. Tesi R. Iinatti J.H.J. Latva-aho M. 《Selected Areas in Communications, IEEE Journal on》2002,20(9):1712-1721
This paper evaluates the level of interference caused by different ultra-wideband (UWB) signals to other various radio systems, as well as the performance degradation of UWB systems in the presence of narrowband interference and pulsed jamming. The in-band interference caused by a selection of UWB signals is calculated at GSM900, UMTS/wideband code-division multiple-access (WCDMA), and Global Position System (GPS) frequency bands as a function of the UWB pulsewidth. Several short-pulse waveforms, based on the Gaussian pulse, can be used to generate UWB transmission. The two UWB system concepts studied here are time hopping and direct sequence spread spectrum. Baseband binary pulse amplitude modulation is used as the data modulation scheme. Proper selection of pulse waveform and pulsewidth allows one to avoid some rejected frequency bands up to a certain limit. However, the pulse shape is also intertwined with the data rate demands. If short-pulses are used in UWB communication the high-pass filtered waveforms are preferred according to the results. The use of long pulses, however, favors the generic Gaussian waveform instead. An UWB system suffers most from narrowband systems if the narrowband interference and the nominal center frequency of the UWB signal overlap. This is proved by bit-error rate simulations in an additive white Gaussian noise (AWGN) channel with interference at global system for mobile communication (GSM) and UMTS/WCDMA frequencies. 相似文献
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We study the problem of adaptive channel estimation for a multipath channel on an ultrawideband (UWB) impulse radio (IR) system. The purpose of the work is to demonstrate that the statistical characteristics of the UWB‐IR environment are strongly non‐Gaussian and that as a result, non‐Gaussian signal processing techniques are both efficient and powerful in a UWB‐IR environment. The multipath channel estimation problem has been chosen as an illustrative example because UWB‐IR systems often operate in complex multipath environments. We study both blind and training‐based estimation techniques and demonstrate that even simple non‐Gaussian strategies can achieve significant performance improvement when compared to more common second‐order estimation techniques. Copyright © 2006 John Wiley & Sons, Ltd. 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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提出了一种基于色散位移光纤(DSF)的交叉相位调制(XPM)效应的超宽带(UWB)光学生成方法。该方法首先利用DSF的XPM效应实现高功率的高斯泵浦光对低功率的直流探测光的交叉相位调制,然后利用光纤布拉格光栅(FBG)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。利用光子仿真软件对方案进行了仿真实验,得到了中心频率分别为7GHz和6.95GHz、相对带宽分别为143%和145%的UWB信号,验证了所提方法的可行性。同时,研究了输入信号脉冲宽度、FBG的反射率、鉴频器的类型对产生的单周期UWB脉冲信号波形和频谱的影响。仿真实验的结果表明,该方案对输入信号脉冲宽度不是过宽的情况下具有良好的容忍度,光学高斯带通滤波器、波分复用器和FBG等光滤波器均可作为鉴频器,采用FBG优点是可通过改变反射率灵活地调整产生的UWB脉冲信号的波形。 相似文献
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In this paper, we develop an analytical framework for performance analysis of generic bit-interleaved coded modulation orthogonal frequency-division multiplexing (BICMOFDM) systems impaired by ultra-wideband (UWB) interference. For practical relevance we consider multi-band OFDM (MB-OFDM), direct-sequence UWB (DS-UWB), and impulseradio UWB (IR-UWB) interference formats following recent IEEE/ECMA standards or standard proposals. Besides the exact analysis we calculate the bit error rate (BER) for the case when the UWB interference is modeled as additional Gaussian noise. Our results show that in general the BER of the BICM-OFDM system strongly depends on the UWB format and the OFDM sub-carrier spacing. While the Gaussian approximation is very accurate for DS-UWB, it may severely overor underestimate the true BER for MB-OFDM and IR-UWB interference. Our analysis is applicable to e.g. IEEE 802.11 wireless local area networks (WLANs), IEEE 802.16 wireless access systems (WiMAX), and 4th generation mobile communication systems. Furthermore, since the ECMA MB-OFDM standard is also based on the BICM-OFDM concept, our analysis can also be used to evaluate the impact of other UWB signals on ECMA MB-OFDM UWB systems. 相似文献