【作者】 李立；

【导师】 陈健；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2008， 硕士

【摘要】 UWB脉冲超宽带是近几年来兴起的短距离无线通信技术。它采用非常窄的脉冲传输数据,具有诸多优点,如系统简单、传输速率高、功耗低、安全性高、多径分辨能力强、定位精确等。DS-UWB是脉冲超宽带的一种,信息码经过伪随机序列扩频后再对发射脉冲进行调制。同步问题是通信接收技术的一个关键问题,适用于DS-UWB的同步技术是目前国内外研究的一个热点。基于UWB同步问题的重要性,针对DS-UWB直扩超宽带系统,本文研究了目前DS-UWB系统的同步方法。针对传统捕获算法速度慢以及UWB信号存在的多径效应问题,仿真分析了改进的两级结构同步捕获算法,能够快速地进行高精度的同步;针对传统的基于最大似然(ML)准则的同步算法普遍具有较低的检测概率问题,仿真分析了改进的基于T&L检测器的同步捕获算法,能够在不增加太多复杂度的情况下很好地提高捕获性能。另一方面,由于UWB信号带宽“超宽”以及由此造成的同步捕获搜索空间过大、存在多个虚同步点等问题,导致目前的同步算法普遍计算量较大,使用目前的数字逻辑器件完全实现算法难度很大。针对这个问题,本文还探讨了如何利用目前现有器件进行系统实现,提出基于FPGA的全数字设计模型,并设计了简化的两级结构同步捕获算法的系统实现方案,用Verilog HDL编写了关键逻辑电路模块。更多还原

【Abstract】 Ultra-wide band(UWB) is a new technology for short-range wireless communication which has recently received a significant amount of attention from academic researchers as well as from the industry.It uses the very short pulses to transmit message and has many advantages such as simple system,high datarate,low power cost,high security,high multipath resolution and precise positioning.DS-UWB is one of the pulse ultra-wide band communication system which uses the PN code to spread the spectrum.Finding the suitable synchronization algorithm for DS-UWB is a hot issue nowadays.In this thesis,the synchoronization algorithms for DS-UWB is analyzed.For the DS-UWB signal is influenced by the multipath channel heavily,the two-stage acquisition algorithm is introduced and analyzed,which has high speed and acquisition precision.For the low detection probability of conventional synchronization algorithms based on max-likelihood principle,the acquisiton algorithm based on Trigg and Leach(T&L) detector is introduced and analyzed,which can achieve 5dB-10dB additional gain compared to the conventional ones. On the other hand,UWB signal is short,low duty cycle,low transmission power and multipath delay influenced.As a result,the searching space is large and there exists more than one phase that can be considerd acceptable.So the rencent algorithms for DS-UWB is complex and difficult for implementated by digital logic device.For that,how to reduce the complexity is discussed and then a whole FPGA based digital system for DS-UWB is introduced.Then,the digital acquisition subsystem is designed,and some key logic modules are created and simulated.更多还原