认知无线电宽带频谱感知关键技术研究

发布时间：2018-05-31 08:34

本文选题：认知无线电 + 宽带频谱感知　；参考：《重庆邮电大学》2014年硕士论文

【摘要】：随着无线通信网络及其应用服务的飞速发展，无线频谱资源严重紧缺的现状已成为实现高性能无线通信服务的最大障碍，，而无线频谱固定分配管理机制又造成大部分频谱资源处于低利用率状态。认知无线电能够动态地利用时间和空间上暂时空闲的频谱资源，因此，被认为是未来实现动态频谱接入、解决频谱资源匮乏问题的关键技术。频谱感知是认知无线电的核心技术之一，是认知系统的基本功能，是实现频谱管理、频谱共享的前提。认知无线电作为新兴的动态频谱接入技术，对授权频段占用状态的实时监测和跟踪是认知环节中最根本、最重要的先决环节。由于次级用户接入授权频段时相对于授权用户的从属地位，要求次级用户尽可能少地对授权用户产生干扰。因此，研究高性能、最优化、易实现的频谱感知技术具有十分重要的意义。本课题以认知无线电为背景，重点对宽带频谱感知进行深入研究。在分析总结传统频谱感知技术优缺点的基础上，借助Gerschgorin圆盘理论以及偏移系数理论对宽带感知技术展开研究，主要工作如下： ①提出基于Gerschgorin圆盘理论的宽带频谱感知算法：Gerschgorin似然估计算法和Gerschgorin圆盘半径估计算法通过引入Gerschgorin圆盘理论实现频谱观测数据空间中噪声圆盘空间和授权用户圆盘空间的准确分离，并基于对授权用户所占用子频带集合势的估计，实现对宽带授权频谱中子频带状态的实时监测。Gerschgorin似然估计算法提高了信息论准则算法的感知性能；Gerschgorin圆盘半径估计算法与传统能量感知相比，其优势在于对信号先验信息的依赖性较低，且受采样次数的限制较小。因此，基于Gerschgorin圆盘理论的感知算法可为宽带感知提供可实现的算法实施方案。 ②提出基于偏移系数的最优协作宽带频谱感知方案通过认知无线电网络中次级用户之间的相互协作，为认知网络的宽带频谱感知提供空间分集，利用融合中心融合多个次级用户的宽带感知数据来获取最优权重，并生成全局检测统计量，最终使用全局阈值完成感知判决。由于所提出的感知方案在获取最优权重的过程中，或需要精确地估计授权用户的信号强度和噪声方差，或感知性能不足。因而，提出更易实现的改进感知方案，有效地降低了对先验信息的依赖度，提高了协作宽带频谱感知的性能。
[Abstract]:With the rapid development of wireless communication network and its application services, the serious shortage of wireless spectrum resources has become the biggest obstacle to the realization of high-performance wireless communication services. However, the fixed allocation management mechanism of wireless spectrum causes most of the spectrum resources to be in the state of low utilization. Cognitive radio can dynamically utilize the temporarily idle spectrum resources in time and space, so it is considered to be the key technology to realize dynamic spectrum access and solve the problem of spectrum scarcity in the future. Spectrum sensing is one of the core technologies of cognitive radio. It is the basic function of cognitive system and the premise of spectrum management and spectrum sharing. As a new dynamic spectrum access technology, cognitive radio (CR) is the most fundamental and important step in cognitive process. Because of the subordinate position of the secondary users to the authorized users when accessing the authorized frequency band, the secondary users are required to interfere with the authorized users as little as possible. Therefore, it is of great significance to study the spectrum sensing technology with high performance, optimization and easy realization. Based on the background of cognitive radio, this paper focuses on broadband spectrum sensing. On the basis of analyzing and summarizing the advantages and disadvantages of the traditional spectrum sensing technology, the broadband sensing technology is studied with the help of Gerschgorin disk theory and offset coefficient theory. The main work is as follows: 1. A wideband spectrum sensing algorithm based on Gerschgorin disk theory: Gerschgorin likelihood estimation algorithm and Gerschgorin disk radius estimation algorithm are proposed. Gerschgorin disk theory is introduced to realize the accurate separation of noise disk space and authorized user disk space in spectrum observation data space, and based on the estimation of the subband set potential occupied by authorized users. The realization of real-time monitoring of the neutron frequency band state of broadband authorized spectrum. Gerschgorin likelihood estimation algorithm improves the perceptual performance of the information theory criterion algorithm. The Gerschgorin disk radius estimation algorithm is compared with the traditional energy sensing algorithm. Its advantage is that it is less dependent on signal prior information and less limited by sampling times. Therefore, the perceptual algorithm based on Gerschgorin disk theory can provide an implementable scheme for wideband sensing. 2. An optimal cooperative wideband spectrum sensing scheme based on offset coefficient is proposed Through the cooperation between secondary users in cognitive radio networks, spatial diversity is provided for broadband spectrum sensing of cognitive networks, and the optimal weights are obtained by fusion center fusion of broadband sensing data of multiple secondary users. The global detection statistics are generated, and the global threshold is used to complete the perceptual judgment. In the process of obtaining the optimal weight, the proposed sensing scheme either needs to accurately estimate the signal strength and noise variance of the authorized user, or its perceptual performance is insufficient. Therefore, an improved sensing scheme is proposed, which can effectively reduce the dependence on prior information and improve the performance of cooperative broadband spectrum sensing.
【学位授予单位】：重庆邮电大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN925

【共引文献】