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基于无线电监测技术的认知无线电频谱检测研究 总被引:2,自引:0,他引:2
认知无线电频谱检测通常将干扰温度作为探测目标,通过估计空间内任意一点的干扰温度并与设定的干扰温度限值比较找出可用频谱.根据干扰温度估计理论算法,结合现代无线电监测技术,可以将无线电监测站的监测、测向系统作为分布传感器直接测定干扰温度估计算法中几个重要的中间未知参数,继而得到考察空间区域内任意一点的干扰温度值.该方法对理论算法进行了实践验证,可以对算法未来的修正、完善提供实践依据,并且对发展无线电监测技术以便为无线电频率资源管理部门制定相应的决策提供技术依据具有重要意义. 相似文献
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认知无线电中基于干扰温度的频谱探测技术 总被引:3,自引:1,他引:2
认知无线电的提出,能够在一定程度上提高频谱利用率,解决目前通信频谱资源紧缺的问题.频谱探测是认知无线电中的关键技术之一,通过频谱探测技术来检测授权用户的频谱空洞,以使得非授权用户能够有效利用.文章介绍了常用的基于干扰温度的探测模型以及频谱估计算法,进行了分析与总结,并且提出了目前频谱探测技术的不足之处. 相似文献
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频谱感知是认知无线电系统的关键技术环节,为了减少系统间的相互干扰,要求频谱感知具有短时性、分辨率高等特点.为此,提出了基于最大熵谱估计的频谱感知方法,理论分析与仿真结果表明,基于最大熵谱估计的频谱感知方法具有感知时间短、频谱分辨率高、系统复杂度低等突出优势,可以作为认知无线通信系统设计的选择方案. 相似文献
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认知无线电(Cognitive Radio,CR)技术通过智能的频谱管理来解决频谱资源"短缺"问题,它能够感知到授权用户的空闲频谱,并有效地加以利用,从而减少与授权用户的冲突。现有无线电参数调整策略无法根据环境变化和用户需求进行智能调整,认知引擎中的决策方法能够解决该问题。遗传算法(Genetic Algorithm,GA)和二进制粒子群算法是实现认知引擎决策的典型算法,在对2种算法进行了介绍之后,仿真比较了2种算法在性能方面的差异。 相似文献
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认知无线电是一种基于软件无线电的智能通信系统,它能够认知周围环境,并能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.授权频段的频谱利用问题是认知无线电实现的关键技术之一.研究了授权频段的两种频谱利用方法:动态频谱接入和基于动态频谱接入模型之一的机会频谱接入. 相似文献
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认知无线网络中基于用户需求和频谱聚合的动态频谱分配 总被引:1,自引:0,他引:1
认知无线电技术可以感知周围无线环境择机利用频谱空洞,从而达到提高频谱效率的目的.在认知无线电网络中,现有的频谱分配算法大部分是基于连续频谱分配并且没有考虑用户的需求.但是连续频谱分配会生成许多小于用户需求的频谱片段,这些频谱片段不能被充分利用,从而造成频谱浪费.本文基于图论提出了一种联合考虑用户需求和非连续频谱聚合的频谱分配算法.在该算法中,非连续的频谱片段被聚合以尽可能多地满足用户总需求,充分利用了小的频谱片段,避免了频谱浪费,从而提高频谱效率. 相似文献
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Thomas M.Trexler 《半导体技术》2004,29(5)
From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test. 相似文献
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The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high. 相似文献
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The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation. 相似文献
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Today, micro-system technology and the development of new MEMS (Micro-Electro-Mechanical Systems) are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible. 相似文献
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Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers
A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it. 相似文献
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A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working. 相似文献
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《中国通信》2014,(7)
正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks 相似文献
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《中国通信》2014,(8)
正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first 相似文献
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LI Shaoqian 《中国通信》2014,(6):I0001-I0002
The global bandwidth shortage of wireless communications has motivated the exploration of the naillimeter wave (ram-wave) frequency spectrum for the next generation wireless communications. Recent advances in RF CMOS technology and high speed baseband signal processing technologies have enabled tile extensive research and development of turn-wave wireless communications. The multi gigabit per second data rate of ram-wave system will lead to applications in many important scenarios, such as WPAN, WLAN,back-haul for cellular system. And the frequency bands include 28 GHz, 38 GHz, 45GHz, 60GHz, E-BAND and even beyond 100 GHz. The propagation and the imitation of the RF circuits design in these frequency bands make the directional antennas be inevitable for mm-wave communications. 相似文献