| Ultra-wideband (UWB, Ultra Wide-Band) wireless communication technology as a new means of communication has become the recent subject of extensive research. As FCC for UWB system, the power spectrum were strictly limited, which leads to the UWB signal design problem. The performance of UWB communication systems not only with the modulation, but also with different pulse waveforms. In the ultra-wideband wireless communication systems, the right to meet the FCC mask requirements of ultrashort pulse waveform design is a key part of ultra-wideband technology.In order to make ultra-wideband narrow pulse will help improve system performance, this paper first analyzes the ultra-wideband signals in multiple access and modulation techniques, in which TH-PPM signal, TH-PAM signal, DS-PAM signal is the main object of study this paper to compare a variety of multiple access and modulation methods advantages and disadvantages, derived TH-PPM program more suitable for UWB communication systems.This article aims to find a suitable pulse, there are many waveforms can be selected as ultra-wideband narrow pulse waveform, a balanced selection of various factors in the practical application of the most commonly used derivative of Gaussian pulse, the high number of different bands derivative function is a combination of resources from low-frequency to high frequency spectrum utilization. In order to improve system performance, to meet the FCC spectrum requirements of the prerequisite conditions, the Gaussian function to determine the minimum pulse forming factor, according to the gradual derivation, using MATLAB to calculate the different Gaussian derivative maximum energy value. Through the identification of the different derivative Gaussian pulses of different pulse forming factors to the achievement of the first derivative function of pulse energy value of the largest, and through MATLAB simulations were achieved by random iteration method and the minimum mean square error (LSE) to assemble pulse, obtained good performance of the pulse waveform, random iterative combination of pulse power spectrum very well developed to meet the FCC indoor UWB radiation mask, and full use of spectrum resources. |
