Research On The Pulse Design And Generation For Ultra-Wideband System

Ultra wide-band technique is a new development in wireless communication field, which is greatly different from traditional communication technology. The bandwidth of UWB signal is much wider than any other current communication signals. As they are characterized with low power spectral density, high data rate, robustness to multipath fading and low cost, UWB systems are particularly promising for dense multipath situations, for example, indoor communications. With the release of the United States FCC spectral mask, UWB technology has attracted increasing interest in both academia and industry.Basic knowledge of UWB technology is introduced firstly, including development history, basic concept and implementation techniques, etc. In the impulse radio UWB solutions, data are transmitted using very short, low duty-cycle, base-band electrical pulses with appropriate shape and duration. Thus there is a close relationship between the characteristics of short pulse and UWB system performance. Theoretical research and simulation are given in this paper.Familiar UWB pulses are introduced firstly, including Gaussian pulse, rise cosine pulse, etc. And then, two novel pulse design methods are proposed. First. combined pulse algorithm is putting forward. The primary task of UWB pulse design is to satisfy the FCC emission mask. We choose wavelet as base function. The diverse translation factors and diverse spectral moving factors of wavelet function are decided according to the emission mask. The principle of linear minimum mean square error (LMMSE) is used in order to get the weighting factors of the combined pulse. Some of the parameters are alterable, thus adding flexibility to applications. Second, orthogonal pulse sequence which satisfy FCC mask is designed. On the basis of deformation Hermite polynomial, secondary Schmidt orthogonal method and combination algorithm work together to generate UWB pulse. The newly generated short pulses are orthogonal and have high spectrum efficiencies at the same time.UWB pulse circuit design by use of the software ADS (advanced design system) is researched in the end. Short pulse is generated based on the instantaneously change of signal in differential circuit. The generated pulse's width and amplitude are flexible while changing component parameters in the circuit.