共查询到20条相似文献,搜索用时 15 毫秒
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随着各种无线通信新技术和新业务的广泛应用,频谱资源日益紧张,如何充分提高频谱资源的利用率便成为亟待解决的问题。应运而生的认知无线电技术,是一种能够主动检测可用频谱资源并能充分利用频谱的新一代无线电技术,这种技术使得无线通信设备具有发现"频谱空洞"并合理利用所发现的"空洞"的能力。认知无线电技术的出现,对解决频谱资源不足、实现频谱动态管理和提高频谱利用率都具有十分重要的意义。 相似文献
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Zhijin Zhao Zhen Peng Shilian Zheng Junna Shang 《Wireless Communications, IEEE Transactions on》2009,8(9):4421-4425
Cognitive radio has been regarded as a promising technology to improve spectrum utilization significantly. In this letter, spectrum allocation model is presented firstly, and then spectrum allocation methods based on genetic algorithm (GA), quantum genetic algorithm (QGA), and particle swarm optimization (PSO), are proposed. To decrease the search space we propose a mapping process between the channel assignment matrix and the chromosome of GA, QGA, and the position of the particle of PSO, respectively, based on the characteristics of the channel availability matrix and the interference constraints. Results show that our proposed methods greatly outperform the commonly used color sensitive graph coloring algorithm. 相似文献
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Sanjay Dhar Roy Sumit Kundu Gianluigi Ferrari Riccardo Raheli 《International Journal of Communication Systems》2014,27(10):1582-1600
In this paper, the performance of cognitive radio (CR) code division multiple access (CDMA) systems is analyzed. More precisely, CR users belong to a cognitive radio network (CRN), which coexists with a primary radio network (PRN). Both CRN and PRN are CDMA‐based, with colocated base stations. Soft hand off and power control are considered in both the CRN and the PRN. Upon the development of an accurate simulator for a representative three‐cell cellular scenario, we evaluate the performance of the proposed CR system in terms of outage probability, blocking probability and average data rate of secondary users. Three different spectrum sensing techniques are. Two new schemes, based on interference limit, are proposed and compared with an existing adaptive spectrum sensing scheme. Spectrum activity measurements and spectrum sharing decisions have been considered for evaluating the performance of the three schemes. The paper proposes a new CR‐CDMA networking model and a simulation testbed for evaluating performances of secondary users and primary users in terms of outage, blocking, BER and average data rate in the presence of soft hand‐off and power control. For comparison purposes, the analysis in the absence of spectrum sensing is also investigated.Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Decentralized spectrum and radio resource management enabled by an on-demand Cognitive Pilot Channel 总被引:1,自引:1,他引:0
This paper presents a framework to achieve an efficient dynamic and decentralized spectrum and radio resource usage in heterogeneous wireless network scenarios. The envisaged technical solution follows a layered approach, where joint radio resource management (JRRM) and advanced spectrum management mechanisms are identified at both the intra- and inter-operator levels. The importance of cognitive network functionalities is highlighted. An on-demand Cognitive Pilot Channel (CPC) is proposed as radio enabler solution for decentralized operation with decision making processes executed at the mobile terminal side. The suitability of the proposed solution is shown by comparison with a broadcast CPC approach. Finally, the paper presents and evaluates decentralized JRRM algorithms both at the intra- and inter-operator levels using the proposed framework. 相似文献
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Klumperink E.A.M. Shrestha R. Mensink E. Arkesteijn V.J. Nauta B. 《Communications Magazine, IEEE》2007,45(5):104-112
Dynamic access of unused spectrum via a cognitive radio asks for flexible radio circuits that can work at an arbitrary radio frequency. This article reviews techniques to realize radios without resorting to frequency selective dedicated filters. In particular, a recently proposed polyphase multipath technique canceling harmonics and sidebands is discussed. Using this technique, a wideband and flexible power upconverter with a clean output spectrum has been realized on a CMOS chip, aiming at flexible radio transmitter application. Prototype chips can transmit at an arbitrary frequency between DC and 2.4 GHz. Unwanted harmonics and sidebands are more than 40 dB lower than the desired signal up to the 17th harmonic of the transmit frequency 相似文献
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针对认知无线电频谱预测效率不高的问题,提出了一种采用深度图像推断的频谱预测算法。该算法将序列预测问题转化为图像推断问题,构建深度图像推断网络实现无线电频谱预测。首先,对历史频谱数据进行预处理,提取频谱数据的变化特征;其次,使用双支路多层并联卷积神经网络提取数据的深度特征,经池化、合并操作输出多层次特征信息;最后,融合不同层次提取的特征信息,实现频谱数据的预测和生成。在真实频谱数据的多个频段对算法性能进行验证,实验结果表明算法能够有效地实现电磁频谱数据的预测,具有预测精度高的特点。 相似文献
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We propose a non-cooperative game theory based algorithm for spectrum management problem in cognitive radio networks taking into account the spectrum handoff effects. The objective is to minimize the spectrum access time of Secondary Users (SUs) which are competing for spectrum opportunities in heterogeneous environment. In this paper, the preemptive resume priority (PRP) M/G/1 queuing model is used to characterize the multiple handoff and data delivery time of SUs. Also an explicit solution for channels selection probabilities of each SU is extracted for PRP M/M/1 model specifically. The effect of handoffs is considered as the interrupted packets which return to the SUs’ low priority queue when the high priority Primary User’s packets are arrived to take service. The queuing delay of SUs’ and the effect of these returned packets are considered in order to balance the load of SUs on channels so that the minimum spectrum access time is sensed by each SU. The non-cooperative spectrum load balancing with handoff management game is proposed to find a distributed solution for each SU. It is shown that this game has a unique Nash equilibrium point which can be achieved by SUs as decision makers. At this equilibrium, each SU incurs the minimum delay on all channels while the free spectrum holes of channels are utilized efficiently. Simulation results are provided to evaluate the performance of the proposed scheme in terms of spectrum access delay, fairness, and channels spectrum holes utilization. 相似文献
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频谱效率、认知技术:频管改革的动力与挑战(上) 总被引:1,自引:0,他引:1
实际测量发现,目前频谱使用中存在着效率低下的问题。为了解决频谱物理资源匮乏与低利用效率之间的矛盾,迫切需要一种动态接入频谱的方式,认知技术由此应运而生。这种免授权频谱使用方式与现有频管部门的固定频率划分机制完全不同,因此,认知技术的出现对当前频管部门提出了严峻的挑战。本文首先介绍了国内外几次著名的实测活动,在此基础上,对动态频谱接入(Dynamic Spectrum Access,DSA)技术以及认知技术的发展过程进行介绍,最后重点从频谱管理层面和工程技术层面上分析了认知技术为频谱管理带来的机遇与挑战。 相似文献
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Xinxin Feng Haobing Wang Xinbing Wang 《Wireless Communications and Mobile Computing》2015,15(3):538-551
We consider the problem of cooperative spectrum sharing among primary users (PUs) and secondary users (SUs) in cognitive radio networks. In our system, each PU selects a proper set of SUs to serve as the cooperative relays for its transmission and in return, leases portion of channel access time to the selected SUs for their own transmission. PU decides how to select SUs and how much time it would lease to SUs, and the cooperative SUs decide their respective power levels in helping PU's transmission, which are proportional to their access times. We assume that both PUs and SUs are rational and selfish. In single‐PU scenario, we formulate the problem as a noncooperative game and prove that it converges to a unique Stackelberg equilibrium. We also propose an iterative algorithm to achieve the unique equilibrium point. We then extend the proposed cooperative mechanism to a multiple‐PU scenario and develop a heuristic algorithm to assign proper SUs to each PU considering both performance and fairness. The simulation results show that when the competition among SUs is fierce, the performance gap between our heuristic algorithm and the optimal one is smaller than 3%. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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本刊讯(记者赵媛)10月23日,中国-东盟无线电频谱管理研讨会在广西南宁顺利召开。此次研讨会的主题是加强无线电频谱管理合作,推动无线电业务发展。来自亚太电信组织(APT)、柬埔寨、印度尼西亚、老挝、马来西亚、缅甸、菲律宾、泰国、越南等东盟成员国信息通信主管部门、无线电频谱主管部门及相关单位的专家参加了研讨会。 相似文献
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多天线系统由于可以提高频谱感知可靠性而被广泛应用于认知无线电中.提出了一种适用于多天线系统的盲频谱检测方法.首先,计算不同天线间接收信号的相关系数;其次,对相关系数做适当的变换使其服从学生分布;最后取变换之后的相关系数的均值作为检验统计量,并推导了其判决门限.理论分析和仿真表明,与噪声方差已知的能量检测(ED)以及基于最大最小特征值之比的频谱盲检测算法(MME)相比,所提算法具有更好的检测性能. 相似文献
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Anna Vizziello Ian F. Akyildiz Ramon Agustí Lorenzo Favalli Pietro Savazzi 《Wireless Networks》2013,19(6):1203-1216
The efficient utilization of radio resources is a fundamental issue in cognitive radio (CR) networks. Thus, a novel cognitive radio resource management (RRM) is proposed to improve the spectrum utilization efficiency. An optimization framework for RRM is developed that makes the following contributions: (i) considering heterogeneous primary users (PUs) with multiple features stored in a radio environment map database, (ii) allowing variable CR demands, (iii) assuring interference protection towards PUs. After showing that the optimal solution is computationally infeasible, a suboptimal solution is consequently proposed. Performance evaluation is conducted in terms of total achieved data rate and satisfaction of CR requirements. 相似文献
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