适用于超宽带信号的多核稀疏字典构造及应用

发布时间：2018-01-05 11:29

本文关键词：适用于超宽带信号的多核稀疏字典构造及应用　出处：《山东大学》2015年硕士论文　论文类型：学位论文

【摘要】：作为采样的重要理论依据,奈奎斯特定理指出：采样速率至少为信号最高频率的两倍才可能精确重构出原始信号。随着信息时代的到来,超宽带技术以抗多径衰落、低截获率、低功耗、安全性能高等诸多优点得到了广泛的关注与应用。由于其极宽的带宽,接收机需要极高速率的模数转换器(ADC)对信号进行采样,加上多径信道复杂性,以奈奎斯特理论为依据的采样方法难以得到实现。因此,超宽带信号的采样问题对超宽带系统的发展造成了一定的阻碍。由Donoho、Cands等人提出的压缩感知(Compressive Sensing,CS)采用一种异于传统的方法,为超宽带信号的采样提供了新的途径。它的特点是以远低于奈奎斯特速率的采样速率对信号进行采样,在该理论框架下,采样速率不再被信号的带宽所限制。本文的研究重点是压缩感知理论中稀疏字典的构造方法,提出了一种多核稀疏字典并应用于超宽带信道估计中。本文的主要工作有以下几个方面：1.提出一种多核稀疏字典的构造方法。该字典在基于单核的多径分集稀疏字典的基础上,进一步采用部分原子导数波形构造辅助稀疏字典,将二者联合作为压缩感知理论中的稀疏字典。通过仿真实验分析了多核字典的性能,结果表明：多核稀疏字典的相关系数性能显著优于单核稀疏字典,初步肯定了我们的设想是可行的,其中只含有一阶导数的多核稀疏字典(即双核稀疏字典)性能最优。2.对双核稀疏字典提出了两种构造方案。第一种方案分别取多径分集稀疏字典和它的导数字典的奇数项构成交叉一阶导数字典,第二种方案分别取多径分集稀疏字典和它的导数字典的前半部分构成叠加一阶导数字典。仿真分析表明：两种双核稀疏字典性能优于多径分集稀疏字典；其中,叠加一阶导数稀疏字典的相关系数更大,重构信号与原始信号的匹配度更高,字典的性能更好,有利于提高信号稀疏性、降低采样率和减小重构误差。3.将叠加一阶导数字典应用到超宽带系统的信道估计中。利用导频信号辅助,采用压缩感知对超宽带信道进行估计,估计结果用于接收机相关解调。对CM1、CM3两种信道模型中的信道估计性能进行了仿真分析,结果表明：与多径分集稀疏字典相比,采用多核稀疏字典进行超宽带信道估计,可以获得更好的误码率性能。
[Abstract]:As an important theoretical basis for sampling, sampling theorem of Nyquist pointed out: two times the rate of at least the highest frequency of the signal can accurately reconstruct the original signal. With the advent of the information age, the ultra wideband technology to anti multipath fading, low interception rate, low power consumption, high safety performance advantages has been widely concerned and applied due. The extremely wide bandwidth, the receiver needs very high rate analog-to-digital converter (ADC) sampling of the signal, plus the multipath channel complexity, taking Nyquist theory as the basis of the sampling method is difficult to be achieved. Therefore, the sampling problem of UWB signal caused some obstacles to the development of UWB system. By Donoho. Compressed sensing proposed by Cands et al. (Compressive Sensing, CS) by using a method different from the traditional, provides a new way for sampling UWB signals. It is characterized by much less than The sampling rate of the Nyquist rate sampling of the signal, under the framework of the theory, the sampling rate is not limited by the bandwidth of the signal. This study focuses on the construction method of compressed sensing theory in sparse dictionary, put forward a multi kernel sparse dictionary and its application in ultra wide band channel estimation. The main works of this paper are the following the following aspects: 1. proposed a method for constructing multiple kernel sparse dictionary. The dictionary based on sparse dictionary mononuclear multipath diversity on the part of the further construction of auxiliary atom derivative waveform sparse dictionary, combined the two as the compressed sensing theory in sparse dictionary. Through simulation analysis the performance of multi-core dictionary the results showed that the correlation coefficient of performance is significantly better than single kernel sparse dictionary multiple kernel sparse dictionary, preliminary affirm our idea is feasible, which contains only one order derivative The multiple kernel sparse Dictionary (i.e. sparse dictionary optimal performance of.2. dual core) put forward two kinds of scheme of dual sparse dictionary. Odd the first scheme were taken multipath diversity sparse dictionary and its derivative dictionary which cross derivative dictionary, second schemes of multi size diversity sparse dictionary and its derivative dictionary the first part of a superposition of a derivative dictionary. Simulation results show that: two kinds of dual core sparse dictionary outperforms the multipath diversity sparse dictionary; the correlation coefficient of superposition of a derivative of sparse dictionary more reconstructed signal and the original signal matching degree is higher, the better performance of the dictionary, is helpful to improve the sparse signal. To reduce the sampling rate, and reduce the reconstruction error of.3. superposition derivative dictionary applied to UWB channel estimation system. Using the pilot signal, using compressed sensing of UWB channel To estimate the estimation results for the receiver demodulation. The CM1, CM3 two channel model in the channel estimation performance is simulated. The results showed that: compared with the sparse multipath diversity dictionary, using multiple kernel sparse Dictionary of UWB channel estimation, can obtain better BER performance.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN925

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