【作者】 王毓东；

【导师】 杨晓冬；

【作者基本信息】 哈尔滨工程大学 ， 通信与信息系统， 2008， 硕士

【摘要】 超宽带通信是目前热点研究的宽带无线通信技术之一。与传统载波通信系统相比,它具有低功耗、频带宽、传输速率高、抗多径衰落能力强、安全性高、设计简单等优点。超宽带通信在军事、高速无线LAN、安全检测、测向定位、雷达等领域都有极其广阔的应用前景,它是无线电领域的一次革命性进展,是未来无线通信的主流技术。在超宽带通信系统中,如果噪声干扰超过接收机的干扰容限时,或者受到外界人为噪声干扰时,系统将不能正常工作,因此,在超宽带系统中研究消噪问题有着重要的实用意义。由于小波变换具有良好的时频分析性能,在超宽带通信系统中,利用小波消噪具有独特优势。本文的主要工作内容是对小波变换在直接序列超宽带系统消噪应用的研究。首先介绍了超宽带通信系统的基本原理,主要是超宽带脉冲信号形成设计方法,超宽带的调制方式和功率谱密度,以及接收机性能等基本技术特点。然后阐述了小波变换的基本理论及其在消噪方面的应用性,在此基础上重点研究了小波消噪理论在直接序列扩频超宽带通信系统中的应用。探讨了阈值消噪法和模极大值消噪法。对模极大值消噪法进行改进,提出了比值门限加相似系数法。该方法既能有效抑制噪声,又能保留超宽带信号的奇异性,并且重构信号方法简单,提高了系统计算速度。仿真结果表明与传统模极大值法比较该算法更简便,消噪效果更明显。更多还原

【Abstract】 UWB communication is one of the hot research topics on the broadband wireless communications technology. Compared with the traditional carrier communication systems, it has many advantages, such as low power, wide frequency band, and high data transmission rate, excellent performance in anti-multipath fading ability, high safety, and simple design and so on. UWB communications has a broad applications prospect in military application, high-speed wireless LAN, security detection, direction finding and location, radar, and other areas. It is a revolutionary progress in the radio field and a mainstream technology in the wireless communications later. In the UWB communication system, if the noise exceeds anti-jamming limit of the receiver, or interfered by artificial noise, the system will not work correctly. Therefore denoising is an important practical issue in the UWB system. It has a unique advantage for using wavelet denoising in UWB, because of the useful time-frequency analysis of the wavelet.This paper is the using of wavelet denoising in DS-UWB. In the first, it presents the basic theory of UWB communication. It includes the design method of UWB impulse signal, modulation and power spectral density of UWB system, the receiver performance and so on. Then the dissertation analyzes the fundamental theory of wavelet transform and its application of denoising. On this basis, wavelet denoising theory using in the direct sequence spread spectrum UWB communication system (DS-UWB) has been studied, and the threshold denoising method and modular maximum denoising method have been discussed. Ratio threshold with similar coefficients has been proposed based on wavelet modular maximum method. It can restrain the noise and reserves the singularity of UWB signals. And the computing speed has been improved because its signal reconstruction method is simple. The simulation results show the new method is simpler and more efficient in denoising than wavelet modular maximum method.更多还原