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在认知无线网络中,针对单节点频谱感知易受到噪声不确定性的影响和传统的能量检测法在高噪声功率场景中检测性能较差等问题,根据Sevcik分形维数(Sevcik fractal dimension, SFD)对噪声不敏感、能够区分信号与噪声波形的特点,提出一种将自适应门限的能量检测法与SFD相结合的协作频谱感知方法. 通过能量检测法对接收信号进行检测判决,然后由SFD对判定为主用户不存在的信号进行复检,并将所有检测结果进行K秩融合,根据融合结果得出最终判决. 仿真结果表明,本文提出的频谱感知方法对噪声不敏感,在低信噪比下的检测性能得到显著提高. 相似文献
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能量检测在认知无线电频谱感知中的应用 总被引:3,自引:2,他引:1
随着无线通信技术的飞速发展,无线电频谱资源日趋紧张。认知无线电已经成为解决现有频谱资源匮乏的非常有前途有前景的技术。认知无线电是一种智能的无线通信系统,它能够感知周围的无线环境,通过一定的方法相应地改变某些工作参数来实时地适应环境,从而达到提高频谱利用率、缓解频谱资源紧张的目的。频谱感知是认知无线电中最具挑战的问题之一。详细介绍了基于能量检测的频谱感知方法,并从理论上分析研究能量检测法的检测性能,最后通过MATLAB仿真分析能量检测法对于OFDM信号的检测性能。 相似文献
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针对宽带频谱认知无线电环境中,传统能量检测法在信噪比较低时,容易出现误检而使系统的检测性能下降的问题,文中提出了一种新型高性能的协作频谱感知算法,它是基于压缩理论的多节点频谱感知方法,各节点之间采用基于双判决门限的协作方式。仿真结果显示,双门限协作压缩频谱感知算法在低信噪比的情况下,检测性能明显优于传统能量检测法。 相似文献
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认知无线电是一种用于提高无线电通信频谱利用率的新的智能技术。文章简述了认知无线电的背景和概念,针对认知无线电的频谱感知能力,详细对比分析了四种频谱检测技术:匹配滤波器法、能量检测法、循环平稳特性检测法和基于干扰的检测法,在此基础上分析了当前频谱检测技术所面临的挑战。最后探讨了干扰温度模型,并展望了频谱检测技术的发展前景。 相似文献
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一种新的认知无线电频谱感知方法 总被引:1,自引:1,他引:0
认知无线电是一种用于提高无线电通信频谱利用率的新的智能技术。首先简述了认知无线电的背景和概念,然后针对认知无线电频谱感知的能力,对比分析了现有的三种频谱检测方法:匹配滤波器法、能量检查法和循环平稳特征检测法,在对其进行研究的基础上,提出一种将能量检测法和循环平稳特征检测法相结合的双门限检测法,通过仿真验证了该方法的有效性和优越性。 相似文献
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传统的频谱感知方法易受噪声波动的干扰,而且在低信噪比的无线通信条件下检测精度较差。通过结合提升小波去噪与动态门限能量检测算法,能有效提高传统频谱感知方法的抗噪声性能和检测精度。首先对含噪信号进行奇偶抽样,分解信号,去除噪声部分,再重构为去噪新信号,然后通过能量检测方法来统计信号的能量积累,设置动态门限,最后以动态门限判断用户信号是否存在。提升小波去噪能够有效地去除采样信号中的噪声,减少噪声对能量检测法检测精度的影响,动态门限能根据噪声波动进行调整来适应复杂的噪声环境。仿真结果表明,提升小波去噪结合动态门限能量检测算法相比于传统的频谱感知要有更优的检测精度。此方法不但提高了其对不确定噪声的抵抗性,使之能适应复杂的通信环境,而且提高了频谱感知过程的可靠性。 相似文献
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针对无线信道环境中,信道多径衰落和噪声不确定性等低信噪比情况下主用户信号检测性能较低的问题,提出一种基于循环平稳人工神经网络(ANN)的主用户信号频谱感知算法。该算法首先对信号特征参数进行提取,作为训练样本和待测样本,再采用ANN算法分别对有无主用户情况下的信号进行分类检测。仿真实验表明,与能量检测法(ED)和循环平稳特征检测法(CD)相比较,所提算法可在低信噪比情况下,不受噪声不确定性等因素影响,具有较高的分类检测性能,有效地实现了对主用户信号的感知。 相似文献
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One of the main requirements of cognitive radio systems is the ability to detect the presence of the primary user with fast speed and precise accuracy.To achieve that,a possible two-stage spectrum sensing scheme is suggested in this paper.More specifically,a fast spectrum sensing algorithm based on the energy detection is introduced focusing on the coarse detection.A complementary fine spectrum sensing algorithm adopts one-order cyclostationary properties of primary user's signals in time domain.Since the one-order feature detection is performed in time domain,the real-time operation and low-computational complexity can be achieved.Also,it drastically reduces hardware burdens and power consumption as opposed to two-order feature detection.The sensing performance of the proposed method is studied and the analytical performance results are given.The results indicate that better performance can be achieved in proposed two-stage sensing detection compared to the conventional energy detector. 相似文献
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In terms of sensing node’s energy and reporting channel’s bandwidth constrains problem for cooperative spectrum sensing in cognitive radio networks,an optimal quantizer design method based on distance criterion was proposed.First of all,the Bhattacharyya distance of received quantized data at the fusion center (FC) was calculated as performance criteria,the optimization mathematical model of the quantizer was constructed,and the optimum quantization thresholds were obtained by using particle swarm optimization algorithm.According to received sensing nodes’ quantized data at the FC,a log-likelihood ratio detector was constructed to decide the presence or absence of primary user signal,the upper bound to sensing performance of energy detector that without quantization was derived.Compared with the existing methods in literatures,the performance of proposed 3-bit quantization method approaches to the upper bound performance of energy detector,under the premise of obtaining comparable detection performance,the requirement of communication bandwidth is reduced. 相似文献
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认知无线电技术可有效地检测到授权频段的频谱空洞,从而提高频谱效率.能量检测由于不需要授权用户的先验信息而被广泛应用.然而由于接收的噪声存在不确定性,使得在信噪比低于某一闸值时,无论观测时间多长,都无法保证检测结果满足要求的检测性能,这一闸值被称作“信噪比墙”.本文通过信噪比墙这一现象进行分析,同时由于协作感知算法在确定噪声下在提高检测性能方便表现出的优势,提出一种基于信噪比墙的协作能量检测算法,通过仿真结果分析,表明本文算法在检测性能和节能上较已有的协作算法具有优势. 相似文献
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Sandeep Kumar 《Wireless Personal Communications》2018,101(2):723-734
Spectrum sensing is the important function of cognitive radio and energy detection is the most popular technique used for spectrum sensing. Detection of the availability of unused spectrum for the secondary user becomes difficult when the channel is affected by composite multipath/shadowed fading. In this paper, the performance analysis of an Energy Detector in Hoyt/gamma composite fading channel with Maximum Ratio Combining employing micro-diversity is analyzed. Analytical expressions for performance parameters, i.e., the average probability of detection and the average area under the receiver operating characteristics curve are evaluate. The effect of diversity on the performance of energy detector is also studied. Monte-Carlo simulation results have verified the accuracy of the proposed analysis. 相似文献
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Because of its ease of implementation and minimum requirements about the primary signals' information, energy detection is broadly considered for signal detection in spectrum sensing algorithms. However, the noise uncertainty phenomenon, caused by the random variations in the noise power, degrades the performance of an energy detector, particularly when the signal‐to‐noise ratio (SNR) is low. In this work, we propose to reduce the negative effects of the noise uncertainty in the performance of an energy detector by dynamically adapting its detection threshold to the noise conditions experienced at each sensing epoch. The noise power is estimated from the received signal samples using an algorithm based on a high‐pass filters bank and median filtering. With our proposal, it is possible to maintain a constant and low false alarm rate in the presence of noise uncertainty, without increasing the probability of misdetection, even in the low SNR regime, and without increasing the number of samples considered for spectrum sensing. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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InSb单晶是制备工作于中波红外大气窗口(3~5 μm)光子型探测器的典型光电转换材料,采用该单晶材料所制备的InSb红外探测器以高性能、大规格像元阵列、高稳定性和相对低成本为特点,广泛应用于军用红外系统和高端民用红外系统领域。然而,InSb 红外探测器响应波长范围固定不可调节、响应仅限于短中波红外而对长波红外无响应、相对有限的载流子寿命制约器件高温工作性能等固有特点,限制了该型探测器在工程中的广泛应用。文中系统地介绍了基于InSb材料人们为改进上述不足所开展的新型材料及其光电响应方面的研究结果。这些材料主要包括:采用合金化方法改变InSb组分形成新型多元合金材料、采用量子结构形成新型低维探测材料。对于新型合金材料,介绍了材料的合金相图、带隙与合金组分的关系、带隙的温度关联特性,并给出采用该材料制备器件的典型光电性能;对于量子结构材料,介绍了材料的制备方法、带隙与量子尺寸的关系,以及采用该材料制备原型器件的典型光响应特性。最后,对新型InSb基红外探测材料与器件的发展趋势、关键问题、研究重点进行了探讨。 相似文献