认知无线电论文：认知无线电 NC-OFDM 加窗技术 旁瓣泄漏

认知无线电论文：认知无线电 NC-OFDM 加窗技术 旁瓣泄漏 认知无线电论文:认知无线电 NC-OFDM 加窗技术 旁瓣泄漏 【中文摘要】随着无线通信的飞速发展,所需要的频谱资源越来越多,当前频谱资源已显得越来越缺乏。认知无线电提供了一种按伺机的方式共享和利用频谱的手段,可以有效地解决这一问题。NC-OFDM是认知无线电主要的数据传输方式,它在传统OFDM基础上进行改进,关闭处于激活状态的授权用户所对应的子载波,感知用户利用非连续的空闲子载波进行通信。在NC-OFDM系统中,每个子载波上传输的信号可以看作是一个非归零矩形信号,其在频域内存在大量的旁瓣功率泄漏,将会对相邻子载波上的信号产生干扰。这一点违背了认知无线电系统存在的前提,即感知用户的通信不能对授权用户的通信产生任何有害的干扰,且授权用户不需要做任何技术或设备上的修改来支持这一功能。因此,在NC-OFDM系统中,除了要考虑系统的自身性能外,还要尽可能降低感知用户对带内授权用户的相对干扰功率。本文针对NC-OFDM系统中感知用户对授权用户的干扰问题展开了研究。首先简要地介绍了认知无线电的、研究意义以及NC-OFDM系统中干扰抑制方法的国内外研究状况。然后概述了基于OFDM的认知无线电系统,给出了OFDM系统的原理框图以及将OFDM技术应用于认知无线电的可行性和技术挑战的分析。文章第三部分给出了时域加窗法在抑制传统OFDM带外功率泄漏方面的仿真分析。在窗函数的选择中,提出了使用具有更小第一旁瓣的优于升余弦窗(BTRC)、二阶连续窗(SOCW)、Franks窗、Double-jump窗来代替原来的升序弦窗(RC)。第四部分着 重研究了将上述五种窗函数应用于NC-OFDM系统时域加窗时,对感知 用户的旁瓣泄漏的抑制效果,并给出了详细的仿真与结果分析。最后, 对全文的工作进行了,并提出了下一步的研究方向。 【英文摘要】With the rapid development of the wireless communication, more spectrum resources are needed and the current bandwidth seems more and more scarce. Cognitive radio(CR) provides an opportunists way of sharing and utilizing the spectrum which can effectively solve this problem. Non-contiguous OFDM (NC-OFDM) is a candidate data transmission method of CR. It is an improved system based on the traditional OFDM. In NC-OFDM system, the rental users transmit their data through the non-contiguous unused subcarriers by closing the subcarriers which are occupied by the licensed users.In NC-OFDM system, the signal transmitted on each subcarrier can be considered as a non-return-to-zero rectangular signal. It can produce serious sidelobe power leakage in frequency domain which will interfere the adjacent subcarriers. Besides, this violates the premise of the existence of the CR system that the rental users’communication can’t produce any harmful interference to the licensed users. Moreover, the licensed users need not to do any modifications on technical or equipment to support this function at all. Therefore, not only the performance requirement for the system itself, but also the corresponding interference power of the rental users to the licensed users should be considered in NC-OFDM system.In this paper, it aimed at the interference power from the rental users to the licensed users. The paper is including the following contents. Firstly, it gives a brief introduction to the emergence background and research meaning of CR, then the studies status of the sidelobe suppressions in NC-OFDM system at home and abroad. Secondly, it mainly summarizes the CR system based on OFDM. And the OFDM system principle diagram is given. The feasibility and technical challenges is analyzed when the OFDM system is applied to the CR. The simulation analysis of using the time-domain windowing to reduce the out-of-band power leakage of traditional OFDM is given in the third part. This thesis presents to apply the windows with smaller first sidelobe, such as BTRC window、SOCW window、Franks window and Double-jump window instead of the RC window in the window’s choosing. The fourth part of this thesis focuses on the sidelobe suppression results of the rental users in NC-OFDM system by applying these five windows. Moreover, the detailed simulation and analysis of the results are given in this part. In the end, it also summarizes the work of this full thesis and points out the future research directions. 【关键词】认知无线电 NC-OFDM 加窗技术 旁瓣泄漏 【英文关键词】Cognitive Radio Non-Contiguous OFDM Windowing technology sidelobe suppression 摘要【目录】基于OFDM的认知无线电时域加窗技术研究 4-5 Abstract 5-6 1 绪论 9-15 1.1 认知无线电 的研究背景及意义 9-12 1.2 基于OFDM的认知无线电旁瓣抑 制技术研究现状 12-14 1.3 本论文的研究内容及章节安排 14-15 2 基于OFDM的认知无线电系统原理分析 15-30 2.1 OFDM系统的基本原理 15-23 2.1.1 OFDM系 统的调制解调原理 16-19 2.1.2 保护间隔 19-20 2.1.3 循环前缀 20-23 2.2 基于OFDM的认知无线电系统概述 23-29 2.2.1 OFDM技术在认知无线电中应用的可行性 23-25 2.2.2 NC-OFDM系统的基本原理 25-28 2.2.3 NC-OFDM系统的挑战 28-29 2.3 本章小结 29-30 3 基于 OFDM的时域加窗技术 30-41 3.1 时域加窗概述 30-32 3.2 OFDM系统时域加窗模型 32-36 3.2.1 时域 加窗的OFDM符号模型 32-33 3.2.2 窗函数达式及特性分析 33-36 3.3 时域加窗的OFDM系统仿真分析 36-40 3.3.1 时域加窗法抑制OFDM系统带外辐射的原理分析 36-37 3.3.2 系统仿真与窗函数性能分析 37-40 3.4 本章小结 40-41 4 基于NC-OFDM系统的时域加窗技术 41-52 4.1 NC-OFDM系统干扰分析 41-44 4.2 NC-OFDM系统时域加窗模型 44-45 4.3 时域加窗的NC-OFDM系统仿真 分析 45-50 4.4 NC-OFDM系统中最优窗的选择 50 4.5 本章小结 50-52 5 总结与展望 52-54 5.1 52 5.2 未来展望 52-54 参考文献 54-57 个人简 历 在学期间发表的学术论文及科研成果 57-58 致谢 58 【索购全文找】1.3.9.9.3.8.8.4.8 1.3.8.1.1.3.7.2.1 同时提供论文写作一对一辅导和论文发表服务。 【说明】本文仅为中国学术文献总库合作提供，无涉版权。作者如有异议请与总库或学校联 系。