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认知无线电系统中频谱感知方法的研究 总被引:1,自引:1,他引:1
由于无线通信技术的飞速发展,因此无线资源频谱日趋紧张.而另一方面现有无线通信网络采用的固定频谱分配策略导致许多已分配的频段在大多数情况下未能被充分利用。认知无线电技术的出现为提高频谱利用率提供了一条新的思路.认知无线电的一个重要要求就是能够动态的感知并接入频段,这就需要人们能够感知出空闲频段。论文主要介绍了认知无线电系统中的频谱感知方法,并运用能量检测法对对OFDM信号进行了仿真分析. 相似文献
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认知无线电频谱分配中为了追求绝对公平而采用随机分配策略,然而由于次用户业务服务质量要求不同,会导致用户中断概率增加.在主用户行为预测模型中应用二状态马尔科夫链,主用户出现概率随机产生,不能反映信道真实状态.为此,提出时频联合检测与实时监测相结合的主用户行为预测,在频谱分配中区分业务类型.仿真结果显示,所提算法次用户平均中断概率优于随机分配机制. 相似文献
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基于数据融合理论的分布式协作频谱感知方法研究 总被引:1,自引:1,他引:0
频谱感知是认知无线电的一个独有特征,是认知无线电的两大核心技术之一.文中通过对比各种频谱感知方法论证了分布武协作感知方法的优越性,提出了基于数据融合理论的分布式协作频谱感知方法. 相似文献
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在认知光通信网络中,能量检测方法因不需要知晓 主用户的参数而被广泛研究,但该方法在噪声波动情形下的感知性能有待提高。该文提出认 知用户根据光通信环境变化自动调整检测阈值的方法来提升低信噪比下的感知性能。融合中 心应用坐标搜索算示为认知用户提供最优控制参数。认知用户以中心阈值为基础,依据最优 参数及自身收集的能量动态设定检测阈值,并通与融合中心的信息交换,学习特定环境下的 最佳阈值。此外,参考了各认知用户在协作感知中的贡献差异,并设计新的权值计算方法来 体现该差异。仿真实验结果表明该文中的频谱感知方法对噪声波动有卓越的鲁棒性,提高检 测概率的同时降低了错误概率,在信噪比为-20dB时的检测概率仍 高达96.9%,远高于传统方法。 相似文献
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Spectrum sensing is one of the core technologies for cognitive radios(CR),where reliable detection of the signals of primary users(PUs) is precondition for implementing the CR systems.A cooperative spectrum sensing scheme based on an adaptive decision fusion algorithm for spectrum sensing in CR is proposed in this paper.This scheme can estimate the PU prior probability and the miss detection and false alarm probabilities of various secondary users(SU),and make the local decision with the Chair-Varshney rule so that the decisions fusion can be done for the global decision.Simulation results show that the false alarm and miss detection probabilities resulted from the proposed algorithm are significantly lower than those of the single SU,and the performance of the scheme outperforms that of the cooperative detection by using the conventional decision fusion algorithms. 相似文献
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S. Nallagonda S.D. Roy S. Kundu P. Kukolev A. Prokes 《International Journal of Electronics》2016,103(2):297-321
In this paper, we investigate the detection performance of cooperative spectrum sensing (CSS) using energy detector in several fading scenarios. The fading environments comprise relatively less-studied Hoyt and Weibull channels in addition to the conventional Rayleigh, Rician, Nakagami-m and log-normal shadowing channels. We have presented an analytical framework for evaluating different probabilities related to spectrum sensing, i.e. missed detection, false alarm and total error due to both of them, for all the fading/shadowing models mentioned. The major theoretical contribution is, however, the derivation of closed-form expressions for probability of detection. Based on our developed framework, we present performance results of CSS under various hard decision fusion strategies such as OR rule, AND rule and Majority rule. Effects of sensing channel signal-to-noise ratio, detection threshold, fusion rules, number of cooperating cognitive radios (CRs) and fading/shadowing parameters on the sensing performance have been illustrated. The performance improvement achieved with CSS over a single CR-based sensing is depicted in terms of total error probability. Further, an optimal threshold that minimises total error probability has been indicated for all the fading/shadowing channels. 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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频谱感知是通信系统抗干扰和智能化的关键能力.针对认知无线电系统窄带频谱感知技术受制于数模转换器件的发展水平,难以解决认知无线电系统宽带、实时频谱感知的问题,提出一种多节点协作的认知无线电系统宽带频谱感知方法.该方法设计由多个认知节点对目标频段执行次奈奎斯特采样来降低采样速率,采用能量检测方式对采样矢量进行集中式融合判决,实现宽频段范围内干扰信号的谱定位和判断,降低各个感知节点的采样速率,支撑认知网络系统构建高实时、宽频带频谱感知的能力.计算机仿真试验结果表明,所提方法达到90%检测概率时压缩比要求为0.025,具有可靠性与有效性. 相似文献
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Suvaditya Majumdar Chandrima Thakur Sudipta Chattopadhyay 《International Journal of Communication Systems》2023,36(1):e5356
In a cooperative spectrum sensing (CSS) network, the primary signal can be used as a radio frequency (RF) source in order to power the energy-constrained sensor nodes of the secondary network. This work presents a novel hybrid model combining an optimal relay selection scheme to incorporate RF energy harvesting in a centralized CSS network. The secondary users, which are equipped with RF energy harvesting capabilities, act as relays in order to forward the sensing information to a fusion center. Here, we have derived an enhanced multi-relay selection strategy to maximize the end-to-end signal-to-noise ratio of the links. Furthermore, a new voting rule is proposed based on the generalized K-out-of-M rule, such that it minimizes our objective error function. The performance analysis of our proposed model is presented with respect to the flexible relay positions. We have used complementary receiver operating characteristic curves for analyzing the detection performance of the CSS model with our derived voting rule. Simulation results using MATLAB show that the proposed model gives a better detection probability and a smaller error rate than some related existing works. 相似文献
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A novel cooperative sensing method is proposed in this paper. The proposed scheme adopts sensing creditability degree to characterize the impact of the distance and the channel parameters on the sensing result, and considers that each user has different average SNR and different decision threshold, by using General Nash Bargaining Solution (GNBS) strategy in Cooperative Game Theory (CGT), the detec-tion performance for two-user case are derived. For multi-user case, the sensing performance is obtained with Hungarian method. Compared with the traditional schemes such as Nash Bargaining Solution (NBS) and AND, the proposed scheme covers all the factors mentioned above, and enhances the sensing rationality and reliability. Simulation results show that the proposed scheme can further improve the sensing performance and creditability. 相似文献