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1、 毕 业 设 计 （ 论 文 ）题 目：认知无线电中频谱感知技术研究专 业： 学生姓名： 班级学号： 指导教师： 指导单位： 日期： 年 月 日至 年 月 日摘 要无线业务的持续增长带来频谱需求的不断增加，无线通信的发展面临着前所未有的挑战。无线电频谱资源一般是由政府统一授权分配使用，这种固定分配频谱的管理方式常常会出现频谱资源分配不均，甚至浪费的情形，这与日益严重的频谱短缺问题相互矛盾。认知无线电技术作为一种智能频谱共享技术有效的缓解了这一矛盾。它通过感知时域、频域和空域等频谱环境，自动搜寻已授权频段的空闲频谱并合理利用，达到提高现有频谱利用率的目的。频谱感知技术是决定认知无线电能否实现的关
2、键技术之一。本文首先介绍了认知无线电的基本概念，对认知无线电在 WRAN 系统、UWB 系统及 WLAN 系统等领域的应用分别进行了讨论。在此基础上，针对实现认知无线电的关键技术从理论上进行了探索，分析了影响认知网络正常工作的相关因素及认知网络对授权用户正常工作所形成的干扰。从理论上推导了在实现认知无线电系统所必须面对的弱信号低噪声比恶劣环境下，信号检测的相关方法和技术，并进行了数字滤波器的算法分析，指出了窗函数的选择原则。接着详细讨论了频谱检测技术中基于发射机检测的三种方法：匹配滤波器检测法、能量检测法和循环平稳特性检测法。为了检验其正确性，借助 Matlab 工具，在 Matlab 平台下
3、对能量检测和循环特性检测法进行了建模仿真，比较分析了这两种方法的检测性能。研究结果表明：在低信噪比的情况下，能量检测法检测正确率较低，检测性能远不如循环特征检测。其次还详细的分析认知无线电的国内外研究现状及关键技术。详细阐述了频谱感知技术的研究现状和概念，并指出了目前频谱感知研究工作中受到关注的一些主要问题，围绕这些问题进行了深入研究。关键词：感知无线电；频谱感知；匹配滤波器感知；能量感知；合作式感知；ABSTRACTThe development of the wireless business results in increasing needs of the frequency. Wi
4、reless communication is facing a challenge. Radio resource is distributed by the government, which generally rises inequality and waste of Radio resource. So，there is a contradiction between the waste and the shortage of Radio resource. The cognitive radio, a technology of intelligent spectrum shari
5、ng, effectively bridges the contradiction. Based on the perception of time domain, frequency domain and airspace，automatic discovery and reasonably use of free spectrum among distributed spectrum，the cognitive radio improves the utilization ratio in the existing frequency. Spectrum sensing is one of
6、 the sky technologies in the cognitive radio.Based on the introduction of Cognitive Radio(CR) and the discussion of applications of CR in WRAN, UWB and WLAN, the key technologies of achieving CR were researched in theory and the factors controlling cognitive network and the interferences raised by c
7、ognitive network in normal working of authorized user were analyzed. The related method and technology of signal detection was theoretically derived in the severe environment of weak signal and low signal to noise ratio that is must facing to achieve CR. With the algorithm analysis of digital filter
8、, the selection principle of windows function was proposed. Three spectrum detection methods namely matching filter detection way, energy detection way and cycle property detection way, were investigation in great detail. For testing and verifying the correction of above results, the detailed modeli
9、ng and simulation of energy detection and cycle property detection were completed with Matlab and the performances of that two detections were also compared. The results show that the energy detection way , in the low SNR , is low and the property of that is very poorer than the cycle property detec
10、tion. And this paper suggested that improvement of algorithm of window function can promote the performance of cycle detection algorithm.Secondly, detailed analysis of the cognitive radio is also and the key technology research status. Elaborated on spectrum the sensing techniques and concepts Resea
11、rch, then points out the research work in the spectrum sensing some of the main issues of concern, around these issues in depth study also.Key Words：Cognitive Radio；Spectrum Sensing；Matched filter Sensing；Energy Sensing；Cooperative Sensing；目 录第一章 绪论 .11.1 认知无线电的研究背景及意义 .11.2 认知无线电技术的国内外发展现状 .11.2.1 国际上和我国认知无线电技术的研究情况 .11.3 全文的主要结构和研究内容 .6第二章 认知无线电技术 .82.1 频谱感知技术 .82.2 频谱分配技术 .92.3 功率控制技术 .102.4 认知无线电技术的应用 .112.4.1 认知无线电在 WRAN 中的应用 .112.4.2 认知无线电在 UWB 系统中的应用 .112.4.3 认知无线电在 WLAN 中的应用 .122.5 本章小结 .12第三章 认知无线电频谱感知技术 .143.1 频谱感知技术系统模型 .
