【作者】 刘佳；

【导师】 马惠珠；

【作者基本信息】 哈尔滨工程大学 ， 通信与信息系统， 2009， 硕士

【摘要】 认知超宽带(Cognitive Ultra Wideband, CUWB)无线通信系统,是结合认知无线电和超宽带技术的主要优点来联合设计研究的一种智能无线系统,是一种基于频谱感知的具有自适应频谱模板和灵活波形的新型超宽带系统。该系统的基本原理主要是利用认知无线电能够感知周围的频谱环境和UWB系统易于数字软件化的特性,依据感知得到的频谱信息和动态频谱分配策略来自适应地构建UWB系统的频谱结构,并生成相应地频谱灵活的自适应脉冲波形,根据信道的状态信息进行自适应地发射与接收。认知超宽带涉及到众多的关键技术,本文从频谱感知及波形设计两个方面对超宽带模型进行了讨论。频谱感知技术的应用可以使超宽带系统感知到其它通信系统的工作情况,重点讨论了能量检测法以及循环特征检测法的检测性能,将二阶循环统计量应用于认知无线电当中,提出了基于二阶循环统计量的改进算法。仿真结果表明,基于二阶循环统计量的频谱感知方法在低信噪比条件下有很好的检测性能,而基于该方法的合作检测方法不仅能够缓解“隐蔽终端”问题,还能进一步提高检测性能。进一步的,本文进行了超宽带波形的设计。对目前讨论比较多的高斯二阶脉冲波形进行了理论分析,并从理论上分析推导了回转椭球波函数(PSWF)的形成过程,证明了其作为超宽带自适应脉冲波形的必然性。仿真结果表明,PSWF相较于高斯脉冲具有很大的灵活性,可以很好的避免对其它通信系统的干扰。更多还原

【Abstract】 Cognitive Ultra Wideband (CUWB) is an intellective communication wireless communication system which combines the advantages of cognitive radio (CR) and ultra wideband (UWB). It is a new ultra wideband system based on self-adapting spectral mask and flexible waveform design. The basic thought of CUWB is that construct spectrum configuration adaptively by making use of the capability of spectrum sensing in CR and the characteristic of USB’s digitalization. At the same time, corresponding self-adapting impulse waveform is generated, transmitted and received according to channel state information.CUWB involves lots of key technologies. In this paper, CUWB basic structure is discussed from two aspects which include spectrum sensing and waveform design. The application of spectrum sensing technology can make UWB "sense" work status of other communication system. At first, methods of spectrum sensing are analyzed and discussed. Further, energy detection and cyclic feature detection are emphatically discussed. The simulation results show that cyclic feature detection has a good performance in the low SNR regime. The cooperative method based on cyclic feature detection not only can solve "the hidden terminal problem", but also improve detection performance.On the basis of spectrum sensing, waveform of UWB is designed. At first, Gaussian second-order impulse waveform is analyzed which is widely discussed by scholars. However, because it is lack of agility and low spectrum efficient it is unsuitable as an adaptive impulse waveform for CUWB. Further, in this paper, the establishment of PSWF is derived from the point of theory. It is proved that PSWF is certain as an adaptive impulse waveform of CUWB. The simulation results show PSWF has high spectrum efficient and can adapt spectral mask of UWB freely compared to Gaussian second-order impulse waveform.更多还原