共查询到20条相似文献,搜索用时 156 毫秒
1.
2.
3.
4.
针对认知无线电网络共享频谱资源的特征,本文提出一种基于扩散机制的分布式宽带压缩频谱感知方法。该算法包含两个工作阶段。在第一个阶段,每个认知用户对观测信号进行压缩感知和独立重构,产生本地频谱估计;在第二阶段,各个认知用户根据扩散机制协作更新频谱估计信息,实现最优估计。仿真结果表明,该算法与一致性分布式压缩频谱感知方法相比,可以快速增强认知无线电网络频谱感知能力,可应用于动态拓扑结构的认知无线电网络。 相似文献
5.
6.
7.
认知无线电是一种具有良好应用前景的通信技术,可以有效提高系统的资源利用率等性能。文中介绍了认知无线电的概念与系统结构,分析了认知无线电系统当中需要重点解决的关键技术,包括频谱感知,动态频谱管理以及信道估计等,并研究与探讨了关键技术的多种典型解决方案,对其性能进行分析与评价,最后对未来应用需要解决的关键问题与热点技术的结合进行了总结与展望。 相似文献
8.
分析了认知无线电网络的集中式、Ad Hoc式和Mesh式体系架构及其节点与链路特性.在认知无线电终端方面,分析了系统组成,并阐述了其认知引擎中环境感知模块、方案制定与优化模块、知识库、知识进化器和接口模块的功能定义以及认知循环过程.最后,论述了认知无线电的频谱感知、频谱分配以及功率控制关键技术. 相似文献
9.
认知无线电及其关键技术 总被引:2,自引:1,他引:1
认知无线电能感知频谱环境,并通过学习实时调整传输参数,实现频谱再利用,是一种能有效提高频谱利用率的新型通信模式。在介绍了认知无线电的基本概念及国内外的研究概况后,着重讨论了认知无线电研究中碰到的几个关键技术:无线电参数智能优化技术、宽带频谱感知技术、宽带数据传输技术等。提出了这些关键技术应着重研究的方向。 相似文献
10.
11.
12.
Xueyuan Jiang Kai‐Kit Wong Yangyang Zhang David J. Edwards 《Wireless Communications and Mobile Computing》2015,15(2):340-353
To utilize spectrum resources more efficiently, dynamic spectrum access attempts to allocate the spectrum to users in an intelligent manner. Uncoordinated sharing with cognitive radio (CR) users is a promising approach for dynamic spectrum access. In the uncoordinated sharing model, CR is an enabling technology that allows the unlicensed or secondary users to opportunistically access the licensed spectrum bands (belonging to the so‐called primary users), without any modifications or updates for the licensed systems. However, because of the limited resources for making spectrum observations, spectrum sensing for CR is bound to have errors and will degrade the grade‐of‐service performance of both primary and secondary users. In this paper, we first propose a new partial spectrum sharing policy, which achieves efficient spectrum sharing between two licensed networks. Then, a Markov chain model is devised to analyze the proposed policy considering the effects of sensing errors. We also construct a cross‐layer design framework, in which the parameters of spectrum sharing policy at the multiple‐access control layer and the spectrum sensing parameters at the physical layer are simultaneously coordinated to maximize the overall throughput of the networks, while satisfying the grade‐of‐service constraints of the users. Numerical results show that the proposed spectrum sharing policy and the cross‐layer design strategy achieve a much higher overall throughput for the two networks. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
13.
认知无线电网络的MAC层关键技术 总被引:2,自引:0,他引:2
认知无线电作为一种智能的频谱共享技术,已成为无线通信领域的研究热点。为达到在不干扰授权用户的条件下有效地实现机会式频谱利用,认知无线电网络的媒体接入控制(MAC)层不仅需要提供传统的服务,还要求能支持一套全新的功能。频谱检测管理通过对检测模式的选取、检测周期及检测时长的设置、检测信道的选取和检测静默期的设置等实现检测策略和参数的选取及优化。接入控制主要采用与授权用户协调接入和透明接入两种方式避免与授权用户的接入产生碰撞。动态频谱分配针对二进制干扰模型和累积干扰模型进行不确定频谱资源的优化分配。安全机制通过增加MAC帧的认证和保密以防御MAC层的安全攻击。跨层设计结合物理层和网络层、传输层等上层信息设计和实现全局优化的MAC层技术。 相似文献
14.
In this paper,the dynamic control approaches for spectrum sensing are proposed,based on the theory that prediction is synonymous with data compression in computational learning. Firstly,a spectrum sensing sequence prediction scheme is proposed to reduce the spectrum sensing time and improve the throughput of secondary users. We use Ziv-Lempel data compression algorithm to design the prediction scheme,where spectrum band usage history is utilized. In addition,an iterative algorithm to find out the optimal number of spectrum bands allowed to sense is proposed,with the aim of maximizing the expected net reward of each secondary user in each time slot. Finally,extensive simulation results are shown to demonstrate the effectiveness of the proposed dynamic control approaches of spectrum sensing. 相似文献
15.
16.
频谱移动的目的是使网络状态变化尽可能快地平滑进行,以确保频谱切换中对通信性能的影响最小。采用基于协作检测的协同频谱感知方法,研究频谱移动的策略,分析频谱池容量对系统性能的影响,设计合适的跨层策略,减小切换延迟,最小化频谱切换对各层的影响。 相似文献
17.
实现频谱共享,需要以实时准确地掌握主用户的频谱占用情况以及频谱交易信息为前提.为此,在利用群智感知以及区块链的前提下,提出了三层式的基于区块链的认知无线电系统,即物理层、传输层以及应用层.其中区块链网络位于传输层,用以记录交易信息,并利用区块链的去中心化以及去信任化特性以保证交易的安全性与可靠性.特别地,为了激励系统中Crowd Sensor积极地参与频谱感知,提出了基于信誉值拍卖的感知收益分配算法.Crowd Sensor依据自身的信誉值对任务进行报价,报价高者可执行任务,且获得较高的收益.仿真结果表明,所提算法保障了感知收益分配的公平性.因此,激励更多的Crowd Sensor参与感知任务可以提升频谱感知的稳定性与安全性. 相似文献
18.
合作频谱感知安全技术研究 总被引:2,自引:0,他引:2
频谱感知是认知无线电实现动态频谱接入的前提和关键技术。由于阴影效应和多径衰落等因素,单个认知用户的频谱感知的结果可能不可靠,因此通过多个认知用户检测结果的融合来提高频谱感知的性能,即合作频谱感知。目前,合作频谱感知存在两类安全威胁:主用户假冒攻击(IE,Incumbent Emulation)和频谱感知数据篡改攻击(SSDF,Spectrum Sensing Data Falsification)。由于这两种攻击的存在,将会大大降低频谱感知的性能,减少认知用户接入空闲授权频段的机会。因此,有必要对这两类攻击开展相关的防御技术研究。 相似文献
19.
20.
Yi Liu Shengli Xie Rong Yu Yan Zhang Xi Zhang Chau Yuen 《Wireless Communications and Mobile Computing》2015,15(17):2079-2094
In cognitive vehicular networks (CVNs), spectrum sensing and access are introduced as the promising technologies to fully exploit the underutilized licensed spectrum. Because the sensing ability of a single secondary vehicular user (SVU) is affected by high mobility, dynamic topology, and unreliable wireless environment, collaborative sensing is developed to increase the sensing accuracy and efficiency. Generally, the synchronization is required in the collaborative sensing in CVN. However, it is difficult to keep all SVUs synchronized with others for sensing under the high dynamic network topology, and the sensing overhead of the synchronous cooperative action may be significant. In this paper, we first propose an asynchronous cooperative sensing scheme in which each SVU provides an energy information (EI) that is tagged with location and time information. The sensing decision will be made on account of the EI. Considering the temporal and spatial diversities of each SVU, we assign different weights to each EI and formulate the probabilities of detection and false alarm as the optimization problems to find the optimal weight of each EI. Then, based on the asynchronous sensing, the specifications of the opportunistic spectrum access mechanism are elaborated in both centralized and decentralized CVNs for the sake of practical implementation. We analyze the system performance in terms of achievable throughput and transmission delay. Numerical results show that the proposed scheme is able to achieve substantially higher throughput and lower delay, as compared with existing schemes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献