共查询到19条相似文献,搜索用时 125 毫秒
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协作频谱感知能提高认知无线电网络的感知性能。随着认知网络频谱感知性能的提高,一方面感知网络将会消耗更多的能量;另一方面次用户拥有更多的机会接入授权频谱,次用户的吞吐量不断增加,同时在通信过程中主用户与次用户发生碰撞的概率也不断增大。本文提出了一种联合优化能量效率和碰撞概率的协作频谱感知算法,通过最优感知检测点判断节点所处信道状态,融合中心舍弃信道状态不好的节点使其不参与数据融合,既消除了信道状态不好的节点对全局判决的不良影响,又提高了能量利用率。仿真结果表明,该算法提高了网络的频谱检测性能,并延长了感知网络的生命周期。 相似文献
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针对无线认知网次用户快速寻找可用信道与检测主用户出现的问题,提出一种新的高效频谱感知机制。该机制通过感知与传输并发以减少感知的时间开销,利用干扰消除技术消除自身传输对感知的干扰;通过结合不同采样速率下信道状态的观察,实现宽频谱的信道感知;在传输中,利用特征匹配技术检测主用户的出现。实验结果表明,新机制可减少感知时间50%,提高吞吐量100%以上。因此,新机制有效降低了频谱感知的资源消耗,提高了认知通信的效率。 相似文献
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刘洋崔颖李鸥刘伟俊 《数据采集与处理》2016,31(4):737-745
为了使认知无线电次用户发现并使用更多的空闲频谱资源,提出了一种多信道频谱感知周期优化算法。针对实际网络中各授权信道使用规律的不同,本文基于交替更新理论建立了多信道状态转移模型,将各信道感知周期的选取建模为一个带约束条件的多目标优化问题,并采用遗传算法对其求解,获得了相对较优的多信道感知周期向量。仿真结果表明,本文提出的目标函数能够有效衡量多信道空闲频谱资源检测率。当目标网络中包含8个授权信道时,所提算法可发现的空闲频谱资源占实际空闲频谱资源的68.23%,相对于以相同周期对各信道进行频谱感知的OFDM机制提高17.68%。 相似文献
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赵永虹 《计算机应用与软件》2015,(2):113-115,123
为了确保认知无线网络中次用户对主用户的干扰低于预定值的同时,最大化次用户系统的吞吐量,减少次用户丢失频谱机会的次数,提出单信道模式下次用户感知时间和传输时间被联合优化的算法。在单信道模型中,次用户以混合接入策略与主用户共享一条信道,通过综合考虑对主用户的干扰和次用户频谱机会丢失两个因素,对传输时间和感知时间进行联合优化。经过与固定的感知时间和传输时间算法仿真分析对比,验证了算法的有效性。 相似文献
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由于协作频谱感知能够更准确地确定主用户的存在与否,因此,它被认为是认知无线电技术中的一个重要研究分支.在协作频谱感知中,各认知用户需要通过报告信道发送其本地判决结果(0或1)到融合中心(FC).然而,在实际中,报告信道通常受衰落的影响,这将降低频谱感知的检测性能.针对这个问题,首先,文中提出一种基于认知用户选择的协作频谱感知算法.该算法通过减小由衰落信道引入的误码概率来提高协作频谱感知的检测性能.其基本思想为:只有具有较好瞬时信道增益报告信道的认知用户才将其本地二进制判决结果发送到FC,否则,该认知用户不发送其本地检测结果到FC.其次,提出一种基于空时编码的协作频谱感知方法.通过在CR网络中,利用空间分集增益来降低由衰落型报告信道引入的误码概率,从而提高检测性能.最后,对提出的这两种协作频谱感知方法的检测性能进行理论分析研究,并对其进行数值仿真.仿真结果表明:相比于传统的协作频谱感知,本文提出的这两种协作频谱感知算法都能提高对主用户的检测性能. 相似文献
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为了提高频谱感知的整体性能,基于链路层多认知用户集中式协作感知思想,提出一种带缓冲区的双周期n步串行协作感知机制.该机制利用多认知用户分时、分段协作提高频谱感知效率,建立频谱池缩短被中断用户切换延迟时间,使用离散马尔可夫模型对感知参数建模,通过求解最优搜索步长和双感知周期比,提高认知用户频谱感知性能和QoS.仿真实验结果显示,该算法在感知效率、被迫中断概率和中断时间方面均优于随机搜索和传统串行搜索策略. 相似文献
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Cognitive radio systems necessitate the incorporation of cooperative spectrum sensing among cognitive
users to increase the reliability of detection. We have found that cooperative spectrum sensing is not
only advantageous, but is also essential to avoid interference with any primary users. Interference by
licensed users becomes a chief concern and issue, which affects primary as well as secondary users
leading to restrictions in spectrum sensing in cognitive radios. When the number of cognitive users
increases, the overheads of the systems, which are meant to report the sensing results to the common
receiver, which becomes massive. When the spectrum, which is in use becomes unavailable or when the
licensed user takes the allocated band, these networks have the capability of changing their operating
frequencies. In addition, cognitive radio networks are seen to have the unique capability of sensing the
spectrum range and detecting any spectrum, which has been left underutilized. Further this capability
of recognizing the spectrum range based on the dimensions detected, allows for determination of
the band, which may be utilized. The main objective of this paper is to analyze the cognitive radio’s
spectrum sensing ability and evolving a self-configured system with dynamic intelligence networks
without causing any interference to the primary user. The paper also brings focus to the quantitative
analysis of the two spectrum sensing techniques namely; Energy Detection and Band Limited White
Noise Detection. The estimation technique for detecting spectrum noise is based on the detection of
probability and probability of false alarms at different Signal-to-Noise Ratio (SNR) levels using Additive
White Gaussian Noise signal (AWGN). The efficiency of the proposed Cooperative CUSUM spectrum
sensing algorithm performs better than existing optimal rules based on a single observation spectrum
sensing techniques under cooperative networks. 相似文献
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Cognitive radio has emerged as a promising technology for maximizing the utilization efficiency of the limited spectrum resources
while accommodating the increasing amount of services and applications in wireless networks. One of the most important and
critical components of the cognitive radio is spectrum sensing and accordingly, detection of primary users. Considering the
hardware constraints existing in cognitive devices, based on the coarse estimation of channel occupancy, partial cooperative
spectrum sensing with adaptive spectrum schedule scheme is proposed to increase the possibility to discover more spectrum
opportunities promptly. Simulation results show the gain of sensing performance and the energy-saving feature of partial spectrum
sensing. Special security scheme is designed to protect the reliability of sensing result from the false message attack. For
the scenarios tested, the proposed scheme is shown to increase opportunities by up to 15 percent. 相似文献
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Cooperative spectrum sensing based on stochastic resonance in cognitive radio networks 总被引:2,自引:0,他引:2
A new censoring cooperative spectrum sensing scheme based on stochastic resonance(SR)technique in cognitive radio(CR)network is proposed in this paper.The observations of the cooperative secondary users(SUs)whose statistics fall into the censoring interval are processed by SR system in the proposed scheme.The hard fusion and the soft fusion for the censoring cooperative spectrum sensing scheme are analyzed respectively.Theoretical analyses and simulation results show that the proposed censoring cooperative spectrum sensing scheme has the same detection performance as and lower computational complexity than the method that each cooperative SU performs spectrum sensing using SR-based energy detection,and its detection performance is superior to that of the conventional method that all the cooperative SUs perform spectrum sensing using energy detection in hard fusion.In soft fusion,the proposed censoring cooperative spectrum sensing based on equal gain combination can achieve the optimal sensing performance approximately. 相似文献
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针对认知车联网中由地形起伏或密集城市结构而引起的频谱感知性能低、延时大等问题,提出了一种基于位置预测的协作频谱感知算法。首先,采用能量检测法进行本地频谱感知,通过将次用户接收到的信号能量大小和预先设定的阈值进行比较,初步判定频谱是否被主用户占用。然后,利用认知车联网中车辆位置预测技术,计算车辆位置和信道状态信息,并据此设置置信值,删除置信值低的次用户。最后,在融合中心采用加入置信值的似然比融合规则得到最终判决结果。仿真结果表明,与传统算法相比,所提算法能有效提高频谱感知性能并缩短感知时间,尤其适用于对实时性要求较高的车联网系统。 相似文献
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认知无线电技术被公认是下一代无线网络的核心架构之一,频谱感知是认知无线电实现的核心手段。通过分析现有的协同频谱感知模型,证明了在多用户进行协同频谱感知的情况下,所有用户进行协同频谱感知所得到总体信道利用率是最高的;进而设计策略促使所有的非授权用户积极进行协同频谱感知,并对所设计的策略进行仿真验证。仿真结果表明,所设计的策略可以有效地促进非授权用户进行协同频谱感知,从而提高频谱资源的整体利用率。 相似文献
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基于可信度的认知无线电协同频谱检测 总被引:1,自引:1,他引:0
认知无线电中随着参与协同检测的认知用户数目的增大,频谱检测性能逐渐增强。但是过多的认知用户参与协同检测,会使整个认知无线电网络的灵敏度降低,同时也会造成巨大的系统开销。针对上述问题,提出了一种新的基于可信度的协同频谱检测方法。在满足目标错误概率的条件下,该算法只选择可信度较高的一些认知用户参与协同频谱检测。仿真结果表明当认知用户中存在恶意节点或者故障节点时,该算法同传统算法相比较,频谱检测性能更好,具有更强的健壮性。 相似文献
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频谱感知是认知无线电研究的关键技术之一,能量检测法是典型的频谱感知方法。针对传统的能量检测法和协同频谱感知存在的局限性,提出一种基于估计噪声的加权协同频谱感知方法,不同认知用户分别通过估计被测频段相邻保护(过渡)频带的噪声特性,近似作为授权用户频带内的噪声特性,以此估计噪声作为信任度进行加权协同数据融合。仿真结果表明,该方法能有效提高频谱检测性能。 相似文献