【作者】 王晓芳；

【导师】 金明录；

【作者基本信息】 大连理工大学 ， 电路与系统， 2011， 硕士

【摘要】 随着对高速数据传输要求的不断增加,高效的使用现有的频谱资源已成为无线通信所面临的一个重大挑战。目前,由于通信用户的增多和频谱分配政策的不合理,使频谱资源变得越来越紧缺。认知无线电(Cognitive Radio,CR)技术的提出为此提供了一种有效的解决办法。认知无线电系统中,通过频谱感知技术来有效的检测频谱的占用情况,进而伺机的使用空闲频段,以达到提高频谱的利用率。因此,空闲频谱的检测技术是认知无线电中必不可少的技术之一,是认知无线电系统得以实现的前提和基础。本文就认知无线电技术中的频谱感知技术展开研究。论文首先介绍了课题研究的背景意义和研究现状,以及认知无线电技术中的特点和关键技术。接着介绍了频谱感知算法的分类、原理、适用范围及优缺点。随后就基于干扰温度机制的合作式频谱感知算法展开了深入的研究。本文通过对基于干扰温度机制的局部多窗口谱估计联合奇异值分解(Local MTM_SVD)算法的研究,针对算法存在的不足提出了一种改进的频谱感知算法。改进算法首先考虑基于干扰温度机制的检测算法中需要对授权用户位置进行准确定位,提出了采用多重信号分类(MUSIC)算法对干扰源信号的DOA进行估计,并计算出干扰源的位置坐标和距离,进一步确定MTM SVD算法中构建的空时复值矩阵的权值系数。同时,原算法中使用了近最优的MTM法进行功率谱密度估计,但同时使用了运算量很大的奇异值分解,且算法中奇异值分解要在每个感兴趣的频点进行,这就使得原算法的运算量很大,难以满足算法对实时性的要求,故改进算法中提出了采用运算量较小的矩阵F范数来代替原算法中的奇异值分解。最后对改进算法的性能进行了比较分析,理论和仿真分析都表明,所提出的改进算法不但能对授权用户进行准确定位,大大提高了算法的实时性,还保留了原有算法好的检测性能。更多还原

【Abstract】 With increasing demand for high-speed data transmission in wireless communications, new chanlleges, such as effectively use of the spectrum resource, generated. At present, the spectrum resource has become ever more scarce, because of the allocation policy is not reasonable and the communications users increase. Cognitive Radio (CR) technique is considered as one of the effective solutions of this problem. To improve utilization of the spectrum, CR employ spectrum sensing to detect the spectrum holes that it is the unused spectrum of a licensed primary user then opportunistic use it. Spectrum sensing is the one of the key technologies in CR networks, so it is the premise and basis of the CR technology.This paper research focuses on CR spectrun sensing technology. Paper first introduces the research background, signigicance and current status, and the characteristics of CR technology and key technology. Then introducing classification of the spectrum sensing algorithm, which the algorithms principle, application congitions,advantages and disadvantages. Finally focuses on research on the cooperative spectrum sensing algorithm based on interference temperature mechanism.Based on the interference temperature mechanism, this paper research on the local multitaper singular value decomposition (Local MTM_SVD) algorithm, then popose a improve spectrum sensing algorithm. The improve algorithm employ the multiple signal classification (MUSIC) algorithm to estimate the directions of arrival (DOA) of the interference source, and can be computed the coordinate position and distance, after can be decided the coefficient in the spatiotemporal complex matrix constructed by MTM_SVD. In the original algorithm, the power spectrum density was estimated by the nearly optimal multitaper method (MTM). But use the singular value decomposition (SVD) with the large amount of calculation at each interest the frequency bin. So the computational complexity of the original algorithm is very large, it is cannot meet the requirement for the real-time. The improve algorithm proposed the matrix F norm with small computational complexity instead the singular value decomposition. Finally comparative and analysis the performance of the improve algorithm. Theoretical analysis and simulation results show that the improve algorithm not only can accurately locate to licensed primary user, greatly improve the algorithm of the real-time, but also can provide the good detection performance.更多还原