| 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. |
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