认知无线电终端的改进设计与实现及ofdm峰均比抑制算法的研究_硕士论文(编辑修改稿)

认知无线电终端的改进设计与实现及ofdm峰均比抑制算法的研究_硕士论文(编辑修改稿)内容摘要：

............................................................................................24 Selection of RadioFrequency Module..........................................................................28 Brief Summary ..............................................................................................................28 3 Design and Implementation of the Software Framework in CR Terminals .........................29 Algorithm Flow in CR Terminals ..................................................................................29 Dispatch of Base Band Algorithms ...............................................................................29 Algorithm Flow in DSP .................................................................................................32 Design of Multitask Software Frameword Based On DSP/BIOS................................34 Brief Introduction of Realtime Multitask Operating System and DSP/BIOS .....34 Design method of software Based on DSP/BIOS ..................................................36 Software Frameword in Transmitting DSP ............................................................36 Software Frameword in Receiving DSP.................................................................39 Brief Summary ..............................................................................................................42 4 Reasearch of Algorithm Reducing the PAPR in CR Experimental System .........................43 Brief Introduction of PAPR Problem of OFDM Signal ................................................43 Definition of PAPR.................................................................................................43 Statistical Properties of PAPR of OFDM Signal ....................................................44 Impact to CR Experimental System Caused by High PAPR .........................................45 Common Algorithms Reducing the PAPR of OFDM signal .........................................47 Signal Distortion Techniques..................................................................................47 Coding Techniques .................................................................................................48 Probability Techniques ...........................................................................................48 Improved Clipping Algorithm Reducing PAPR of OFDM signal.................................49 Basic Idea of Clipping Algorithm...........................................................................49 西安交通大学硕士学位论文 VIII Improved Clipping Algorithm ................................................................................50 Selection of Parameters in Improved Clipping Algorithm .....................................52 Simulation Result of Improved Clipping Algorithm ..............................................53 Implementation of the Improved Clipping Algorithm in CR Experimental System.....54 Brief Summary ..............................................................................................................56 5 Testing and Debugging of Hardware and Software Framework in CR Terminals ...............57 Debugging of Hardware in CR Terminals .....................................................................57 Debugging of Power Module .................................................................................57 Debugging of Clock Module ..................................................................................59 Signal Integrity Testing of High Speed Digital Signals .........................................61 Debugging of Software Framework in CR Terminals ...................................................62 Configurating the Underlying Hardware ................................................................62 Interface of All Algorithm modules........................................................................63 Timing and Realtime Properties of All Algorithm Tasks ......................................64 Brief Summary ..............................................................................................................64 6 Conclusions and Suggestions ...............................................................................................65 Conclusions ...................................................................................................................65 Suggestions ....................................................................................................................65 Acknowledgements .................................................................................................................66 References ...............................................................................................................................67 Appendice ................................................................................................................................69 Achievements ..........................................................................................................................70 Declaration Equation Chapter 1 Section 1 1 绪论 1 1 绪论 无线通信从出现到现在短短几十年 时间 ，历经几代变革，到现在呈现多种无线通信系统共同发展的态势。 目前各个无线通信系统在 政府有关部门 的 授权 下使用各自的通信频段和带宽。 这种静态的无线频谱管理方式，虽然可以简单有效地避免不同无线通信系统间的相互干扰，但常常导致 频谱利用率非常低 [1]。 并且对于日益增长的无线通信带宽需求和新出现的通信系统没有很好的支持，成为无线通信技术发展的瓶颈。 在此背景下 ，认知无线电 技术被提出用于提高频谱利用率， 解决 不断增长的频谱资源需求与当前效率低下的频谱管理方式之间的矛盾。 认知无线电研究现状 1999 年 Joseph Mitola 在软件定义无线电 (Software Defined Radio, SDR)基础上 提出认知无线电 (Cognitive Radio, CR)[2]。 其 基本思想是认知无线电系统 能够 感知 周围的 无线通信环境 ， 动态检测和有效利用 已 被 分配但暂时未使用或者 未 完全使用的 频谱 ， 根据一定的学习和决策算法 ， 实时自适应地改变系统工作参数 ， 在时间、频率以及空间上进行多维的频谱复用 ，从而提高频谱利用率 [3]。 在 Mitola 之后， Fatih Capar 提出 一种比较简单，容易实现的认知无线电定义 [4]，将 认知无线电 定义为 一种智能化、动态频谱资源管理使用方式，授权用户拥有最高的频谱使用优先级，它可以和若干具有低优先级的认知用户分享频谱资源，以提高频谱资源利用率。 目前国际上开展的 CR 研究大多采用类似的 简化 定义。