小波包分复用论文：基于小波包分复用技术的多载波通信系统研究.doc

小波包分复用论文：基于小波包分复用技术的多载波通信系统研究【中文摘要】随着3G通信技术日渐成熟并步入商业化运营,下一代无线通信系统的研制已经被提上议事日程。多载波通信与先进调制技术的结合,以其较高的频谱利用率,良好的抗衰落能力,被认为是下一代无线通信系统中的核心技术。小波包分复用技术不仅具有良好的抗码间干扰、载波间干扰的能力,且相比OFDM技术具备更佳的信道适应能力,成为近一段时间研究的热点。然而,峰均功率比较高、子载波基的选择以及最优基选取方法较复杂等难题一直制约着小波包分复用技术的进一步发展与应用。本文则针对上述问题,进行了深入而细致的研究。全文首先概括并阐述了多载波调制与小波包分复用技术的研究现状及发展前景,介绍了时频分析与小波包理论,并以此为基础,分析了在多径衰落信道模型下,子载波基的选取对系统抗干扰性能的影响。给出了频率弥散信道中子载波基的选取原则,提出以小波包函数替代传统OFDM技术中所采用的正弦基作为子载波基进行传输,利用小波包函数良好的自正交性与互正交性,来获取更优的抗噪声与抗干扰性能。实验结果验证了本方法的可行性与有效性。接着分析了小波包基的构成原则与选择方法,针对多载波通信系统的性能要求,选取ICI与ISI联合功率及峰均功率比作为度量准则,并将子载波数目作为搜索约束条件,提出了一种基于根节点逐级向下按二进支路分解,利用度量准则函数决定父子节点间取舍的最优基搜索算法,并解决了约束条件下的最优基输出问题。最后在4径Rayleigh衰落信道模型下的仿真结果表明:该算法的运算速度优于现有的两种算法,且采用最优基结构的系统比全分解结构的系统性能提升约20%。最后,总结了全文的主要工作,指出了本文研究的局限性与不足之处,展望了小波包分复用技术及多载波通信技术的未来发展趋势。【英文摘要】With the maturity of 3G communication technology and already into commercial operation, the development of next generation wireless communication systems have been put on the agenda. Advanced modulation combined with multi-carrier communication, with its high spectral efficiency, good anti-fading ability, is considered as the key technology in next-generation wireless communication system. Wavelet packet division multiplexing does not only have good anti-ISI, ICI ability, but also has better ability of adapting to the channel than OFDM technology. However, difficulties in high peak to average power ratio, sub-carrier bases selection and optimal basis selection has restricted the further development and application of wavelet packet division multiplexing. This thesis will address the above issues, and process deep and meticulous research.This thesis first summarized and described the current statue and future prospects of multi-carrier modulation and wavelet packet division multiplexing, introduces the time-frequency analysis and wavelet packet theory. Based on that, this thesis analysed the anti-interference performance. of different sub-carrier bases in multi-path fading channel, and given the selection principle of sub-carrier bases in frequency dispersion channel, wavelet packet function is proposed to replace the traditional sine-base used in OFDM technology for transmission, using its self and cross orthogonality to obtain better performance against noise and interference. Experimental results demonstrate the feasibility and effectiveness of this method.In the following part, analyzed the composition and selection principle of wavelet packet basis, and a novel search algorithm for wavelet packet basis was proposed. This algorithm decomposes the whole wavelet packet library from top to bottom by its binary branch, use ICI and ISI integrated power and Peak to Average Power Ratio (PAPR) for competitive decision to select optimal basis. Finally the algorithm was tested in 4-path Rayleigh fading channel. Simulation results indicated that: the operation speed of the algorithm is better than two existing algorithms, and the output of the optimal basis structure gain about 20% performance increase than full decomposed structure.Final chapter is the summary of the main work and future trend of the wavelet packet division multiplexing and multi-carrier communication technology.【关键词】小波包分复用 多载波通信 子载波基 最优基 峰均功率比 正交频分复用【英文关键词】Wavelet packet division multiplexing Multi-carrier communication Sub-carrier basis Optimal basis peak to Average power ratio Orthogonal frequency division multiplexing【目录】基于小波包分复用技术的多载波通信系统研究摘要4-5ABSTRACT5第一章 绪论8-141.1 引言8-91.2 研究背景及现状9-121.2.1 多载波调制技术9-111.2.2 小波包分复用技术11-121.3 本文的主要内容及结构12-14第二章 多载波调制系统14-202.1 单载波调制142.2 多载波调制14-162.2.1 多载波调制的原理14-152.2.2 多载波调制系统的优缺点15-162.3 多载波调制系统的实现16-192.3.1 MC-CDMA 系统16-172.3.2 OFDM 系统17-182.3.3 WPDM 系统18-192.4 本章小结19-20第三章 小波理论与小波包分复用20-303.1 时频分析与小波理论20-253.1.1 Fourier 变换20-213.1.2 Gabor 变换213.1.3 小波变换21-243.1.4 小波包变换24-253.2 小波包分复用系统25-293.2.1 小波包分复用系统的原理与结构25-283.2.2 WDPM 的特点与优势28-293.3 本章小结29-30第四章 多载波通信系统中子载波基的选取30-404.1 引言30-314.2 无线通信信道31-344.2.1 无线传播环境的多样性与多径性31-324.2.2 无线信道中的衰落类型32-334.2.3 无线信道模型33-344.3 子载波基的优化选取34-374.3.1 问题的提出34-354.3.2 信道干扰的理论分析35-364.3.3 子载波基的优化选取36-374.4 仿真分析与结论37-384.5 本章小结38-40第五章 小波包分复用系统中的最优小波包基选择40-515.1 引言40-415.2 最优小波包基的定义41-425.3 现有的最优基选取方法42-455.3.1 最优基搜索算法42-435.3