Research On UWB Radio Waveform Design

Ultra-Wide Band(UWB) wireless communication technology is an approach of sharing ultraly wide electromagnetic spectrum. Differing from the traditional wireless one using carrier, The UWB communication system, which is provided with low radiated power, insensitivity to channel fading, high data transmission rate, low probability of interception, excellent positioning accuracy and work performance, low system structure complexity with inferior hardware cost, and ultraly less power dissipation, directly makes use of pulse signals within nanosecond or picosecond width to transmit information. In addition, it can be settling the issue of shortage of radio spectral resources in parallel with safe and efficient communication.This thesis makes a more in-depth research into the waveform design of UWB radio. The main contents are as follows:(1) Several types of impulse waveforms on UWB communication systems are mainly investigated: Gaussian impulses, Raised Cosine impulse, Hermite polynomial impulse, and the orthogonal type of the third— Hermite-Rodriguez(HR) pulse waveform. And the features of the above signals: time-domain waveform, energy spectrum density(ESD), power spectrum density(PSD) have been analyzed with their advantages, shortcomings as well as the practical application values also be compared mutually.(2) The modulation and transmission performance of UWB signals are explored, which is primarily involved in the typical generation methods together with the modulation performance for the binary pulse position time-hopping modulation UWB(2PPM-TH-UWB) signal and the binary pulse amplitude direct-spread-spectrum modulation UWB(2PAM-DS-UWB) one. Simultaneously, the features of transmission distance, signal-to-noise ratio(SNR), bit-error-rate(BER), and data rate of orthogonally multiple-nary pulse position modulation(PPM) and pulse amplitude modulation(PAM) are analyzed and demonstrated, their mutual relations included.(3) Based on the Emission Mask criterion(call it FCC-EM in the following) of UWB released by the Federal Communication Committee(FCC), two simple UWB design methods are proposed, i.e. the one— Random Coefficients-Weighted Method(RCWM), the another— Least Square Error(LSE). Then the usage of Gaussian impulse plus HR pulse in simulating RCWM and LSE indicates that the two proposed approaches are efficient and reliable.(4) Inspired by the relevant references, an iterative algorithm for UWB waveform designs on the basis of Spectrally Constrained Optimation Method(SCOM algorithm) is proposed. SCOM disposes of the following issues that have existed in the traditional method: lower efficiency, inaccurate frequency range, ineffective to control the radiated power of the individual frequency point etc., improving the original algorithm’s performance against the sensitivity and dependence on initial signal, insufficient depth of spectrum notches, excessive iteration numbers, along with difficult convergence. A simulation proves SCOM capable of working out validly the expected UWB waveforms in accordance with upper limit of User-Defined Emission Mask(UDEM). At the same time, in spectrum notch depth from 30 to 40 d B, the performance of SCOM about iterative numbers and time fights against the original one. On the other hand, it successfully exceeds the original method in spectral notch generation, convergence, power control capability.