基于认知无线电技术的频谱资源利用的研究

1、博士学位论文基于认知无线电技术的频谱资源利用研究STUDY OF SPECTRUM RESOURCEUTILIZATION BASED ON COGNITIVE RADIO国内图书分类号：TN914国际图书分类号：621.39学校代码：10213密级：公开工学博士学位论文基于认知无线电技术的频谱资源利用研究博 士 研 究 生：林威导师：张乃通教授申 请 学 位：工学博士学科：信息与通信工程所 在 单 位：电子与信息技术研究院答 辩 日 期：2010 年 10 月 15 日授予学位单位：哈尔滨工业大学Classified Index: TN914U.D.C.: 621.39Dissertatio

2、n for the Doctoral Degree in EngineeringSTUDY OF SPECTRUM RESOURCEUTILIZATION BASED ON COGNITIVE RADIOCandidate：Supervisor：Academic Degree Applied for：Speciality：Wei LinProf. Zhang Nai-tongDoctor of EngineeringInformation and CommunicationEngineeringAffiliation：Date of Defence:Degree-Conferring-Inst

3、itution:School of ElectronicsInformation TechnologyOctober 15, 2010Harbin Institute of Technologyand摘摘要要认知无线电技术在提出以后一直被认为是解决频谱拥塞和频谱利用率低下之间矛盾的有效途径，可应用于以伺机方式使用授权频段的空闲频谱资源的非授权系统中，如 IEEE 802.22 系统通过认知无线电技术利用广播电视频段来实现偏远地区的宽带接入。尽管包括 802.22 在内的非授权系统的标准化工作已经进行了多年，然而到目前为止，应用前景依然不太明朗。解决有效频谱利用的问题不能只依靠非授权系统来解决，

4、对于正在运营的授权系统也同样需要考虑如何提高频谱利用效率。提高主流的授权无线系统的频谱利用率会更有效地解决无线频谱资源的利用问题。不同系统间存在频谱资源利用不均的问题，有些系统的频谱利用率一直都比较低下；有些系统虽然整体频谱利用率较高，但在某些时段和某些地区也存在利用率低下的问题。通过在不同的系统之间进行频谱共享和频谱资源再分配，可以解决频谱资源利用不均的问题。非授权系统通过伺机频谱利用的方式与授权系统实现频谱共享，这种方式也可以推广到其他系统中解决在异构网络环境下的频谱资源分配问题。伺机利用频谱的认知无线电系统首先需要发现可利用的频谱资源，频谱利用的效果与频谱检测的性能、频谱接入的策略密切相

5、关，频谱检测和频谱接入都是本文的研究问题。本文主要包括以下研究内容：第一，界定了频谱资源的概念，分析了各种无线技术对频谱资源的利用的不同情况，并从频谱空间的角度进行了归纳。在频谱资源空间模型基础上，对认知无线电技术应用于非授权系统与授权系统的不同情况分别加以说明，并指出两种不同情况在关键技术和研究重点上的差异。分别针对认知非授权系统与认知授权系统的频谱资源利用方案，给出了评价标准的一般框架。第二，分析了不同的检测方法的检测性能和噪声不确定度对其的影响；提出了离散和连续形式的噪声不确定度模型，并给出了以平均检测概率和虚警概率为评价指标的检测器的设计准则。相比以往对噪声不确定度下的检测性能研究给出

6、了更准确的分析。检测器的判决门限可以通过噪声方差分布的先验知识来确定，从而得到噪声不确定下的最佳平均检测性能。第三，从多传感器数据融合角度研究认知无线电系统合作感知问题。忽略-I-哈尔滨工业大学工学博士学位论文不可靠用户的检测结果，采用部分融合的方法可以提高认知无线电系统的检测性能。通过研究发现对于特定的在线用户规模，存在一个最佳的参与融合用户数。可以固定选择每次检测的融和用户数使系统平均检测概率最大，或根据每次检测的接收信号状况动态调整参与融合的用户数可以使每次检测的性能最佳。第四，在多模终端和认知无线电技术基础上提出以终端为主导的频谱分配方案，并与以网络为主导的集中式频谱分配方案进行比较。

7、从运营商角度讲，尽管以终端为主导的频谱分配方案中每个用户并不知道其他用户的情况，仍然可以通过合理有效的接入策略可以达到较高的频谱利用效率，在有些条件下甚至可达到与全局优化方案相同的利用效率。从用户角度讲，多模终端的自主切换有利于在移动环境中保障用户的业务 QoS。第五，说明了未来无线通信对下一代多模终端的需求，并对认知无线电技术在下一代多模终端中的应用前景及实现可行性进行了分析。提出了一种基于认知无线电技术的多模终端的体系结构及其工作机制以支持频谱资源分配方案，并对终端实现所需的各种使能技术进行了论述。第六，提出了认知无线电系统的建模方法及仿真系统的设计。仿真系统基于面向对象的设计思想，有利于

8、仿真系统的扩展和改进。仿真系统采用离散事件驱动机制可以对系统运行的整个过程进行模拟。仿真系统以信道作为关注的焦点，也可直接观察到所有收发信机的情况，便于对频谱资源的利用情况进行评价。关键词：认知无线电；频谱资源利用；异构网络；智能终端- II -AbstractAbstractCognitive radio (CR) technology has been considered as a solution to theconflict between spectrum congestion and spectrum under-utilization since it wasproposed.

9、 It is applied in unlicenced systems which access the licensed spectrumbands in an opportunistic way. As an example, IEEE 802.22 system based on CRuses the broadcasting TV bands to realize the wideband spectrum access in ruralarea. Although the standardization work has been underway for many years,

10、theprospect of commercial application is still unclear. Spectrum utilization problemcan not be solved by unlicensed systems. Licensed systems also need to improvethe spectrum utilization efficiency to solve the spectrum utilization problem.Unbalance exists in the spectrum utilization of various wire

11、less systems.Specturm utilization of some systems is low most of the time. And spectrum ofsome systems is under-utilized in some time and some area. Spectrum sharing andspectrum re-allocation among different systems can reduce the unbalance inspectrum utilization. Unlicensed systems share spectrum r

12、esource with licensedsystem in an opportunistic way. This method can also be applied in other systems tosolve the spectrum resource allocation problem in heterogeneous networkenvironment.Cognitive radio systems should discover the available spectrum resourcebefore using it. The effect of spectrum ut

13、ilization is closely related to the spectrumdetection performance, and spectrum access strategy, both of which are discussed inthis dissertation. The major research contents consist of the following parts:The concept of spectrum resource is illustrated. Different ways of usingspectrum resource of va

14、rious wireless technologies is concluded in the perspectiveof spectrum space. Based on the spectrum resource space model, the situations ofunlicensed system and licensed system are explained, the differences between thesetwo situations are also pointed out. A general framework of evaluation criterio

15、n ofspectrum utilization is proposed.The performance of different detection methods and the influence of the noiseuncertainty are analyzed. Discrete and continous forms of noise uncerntainty modelare proposed. The design criterion is given using average detection probability and- III -哈尔滨工业大学工学博士学位论

16、文average false alarm probability as the indictors to evaluate the detectionperformance. Compared with traditional research in the detection under noiseuncertainty, the model proposed in this thesis is more accurate. If the threshold ofthe detector is determined according to the prior knowledge of no

17、ise variancedistribution, the average detection performance will be achieved.The cooperative spectrum sensing issue is studied in the perspective of multi-sensor data fusion. Neglecting the detection result of some unreliable users, thedetection performance can be improved by allowing part of the us

18、ers participated indata fusion. For a certain amount of online users, there exsits an optimal number ofusers participated in data fusion. Selecting a fixed number of users participated indata fusion as the optimal value can maximize the average system detectionprobability. Dynamically adjusting the

19、number of users participated in data fusionby measurement can maximize the detection performance in each detection.Terminal-dominated spectrum allocation scheme is proposed on thefundamental of multi-mode terminal and cognitive radio technology. From the viewof network operators, although each user

20、doesnt know the situation of other usersin this scheme, high effiency of spectrum utilization of this scheme will be achievedwith proper access strategy. From the view of users, the automatic tradeoff amongheterogenous network of multi-mode terminal is helpful to ensure the QoS ofapplication for the

21、 users in a mobile environment.The requirements for the next generation multi-mode terminal are described.The prospect and technological viability of multi-mode terminal is analyzed. Thearchitecture and operating mechanism of CR-based multi-mode terminal isproposed to support the terminal-dominated

22、spectrum allocation scheme. Enablingtechnologies needed by the intelligent terminal are discussed.Modeling method and design of simulator of cognitive radio system areproposed. The simulator is based on object-oriented design thought, which isbenefit for the extention and adaptation of the functions

23、 of the simulator. Thesimulator applies discrete event driven mechanism to emulate the process of systemoperating. Channel is the focus in the simulator, and the situation of all thetransceivers can be directly observed all the time, which makes it easier for theevaluation of spectrum resource utili

24、zation.- IV -AbstractKeywords: Cognitive radio, Spectrum resource utilization, Heterogeneous network,Intelligent terminal-V-哈尔滨工业大学工学博士学位论文目录摘要.Abstract.第 1 章 绪论.11.1 课题研究的意义、来源和目的.11.2 认知无线电技术概述 .31.2.1 认知无线电提出的背景.31.2.2 认知无线电的概念 .51.3 认知无线电技术研究现状.91.4 认知无线电研究的关键技术.111.4.1 频谱感知.111.4.2 频谱共享与频谱接入技术.

25、151.4.3 频谱分析与决策.201.5 异构无线网络环境的频谱资源分配.211.6 论文的主要研究内容和结构.23第 2 章 频谱资源利用模型及评价标准.262.1 频谱资源的利用 .262.1.1 系统内的频谱利用.272.1.2 系统间的频谱利用.342.1.3 频谱资源空间.352.2 认知无线电系统的频谱资源利用.362.2.1 非授权系统.372.2.2 授权系统.382.3 频谱资源利用的评价标准.382.4 本章小结.40第 3 章 伺机频谱接入系统的频谱感知.413.1 基于单一设备的频谱检测.413.1.1 能量检测.413.1.2 相干检测.473.1.3 认知无线电系

26、统检测器设计权衡.49- VI -目录3.2 噪声不确定度下能量检测的设计准则.513.2.1 统计量判决门限的设定.513.2.2 噪声不确定模型 .543.2.3 数值结果及讨论.553.3 基于数据融合模型的合作频谱感知.573.3.1 多传感器数据融合系统模型.573.3.2 数据融合准则 .583.3.3 合作感知性能分析.603.4 部分可靠用户参与融合的合作检测.683.4.1 基于统计的最佳融合用户数的检测方案.683.4.2 基于检测的最佳融合用户数的检测方案.693.4.3 算法仿真与结果分析 .703.5 本章小结.73第 4 章 终端主导的异构网络频谱资源分配.744.

27、1 异构网络环境下的频谱资源分配.744.1.1 基于网络的异构网络频谱资源分配方案.744.1.2 基于终端的异构网络频谱资源分配方案.744.1.3 两种资源分配方案的比较.754.2 终端的频谱接入策略.764.2.1 系统模型.764.2.2 频谱接入策略的评价标准.774.2.3 基于需求的接入策略.784.2.4 基于需求和信道状况的接入策略.814.2.5 仿真与结果分析.834.3 基于认知无线电技术的智能多模终端.854.3.1 智能终端的需求分析.864.3.2 智能终端体系结构设计.884.3.3 使能技术.894.4 本章小结 .98第 5 章认知无线电系统仿真平台 .

28、1005.1 认知无线电仿真器概述.1005.1.1 对象管理 .1015.1.2 事件调度机制 .101- VII -哈尔滨工业大学工学博士学位论文5.1.3 数据统计 .1015.1.4 移动性支持 .1025.1.5 脚本解释器 .1025.2 仿真平台的设计.1035.2.1 公共基类 .1035.2.2 信道类 .1035.2.3 链路类 .1045.2.4 收发信机类 .1055.2.5 事件及处理器类.1065.2.6 移动节点类 .1085.2.7 认知无线电系统设备类.1085.3 伺机频谱接入系统仿真.1105.3.1 系统模型.1105.3.2 仿真结果及分析.1125.

29、4 认知无线电多模终端.1145.4.1 仿真系统的扩展 .1145.4.2 仿真场景 .1145.5 本章小结.116结论 .117参考文献 .120攻读博士学位期间发表的论文 .134哈尔滨工业大学博士学位论文原创性声明 .135哈尔滨工业大学博士学位论文使用授权书 .135致谢 .136个人简历 .137- VIII -ContentsContentsAbstract (In Chinese).Abstract (In English).IChapter 1 Introduction.11.1 Background, objective and significance of the s

30、ubject.11.2 Overview of cognitive radio.31.2.1 Background of cognitive radio.31.2.2 Concept of cognitive radio.51.3 Research status of cognitive radio.91.4 Key technologies of cognitive radio.111.4.1 Spectrum sensing.111.4.2 Spectrum sharing and spectrum access. 151.4.2 Specturm analysis and decision.201.5 Spectrum resource utilization of heterogeneous wireless networks.211.6 Main research contents and structure of this thesis.23Chapter 2 Model and evaluation criterion of spectrum resource utilization.262.1 Utilizaiton of spectrum resource.262.1.1 Intra-system spectrum utilizatio