独立分量分析应用于OFDM系统频偏和信道估计研究

发布时间：2018-05-01 03:20

本文选题：正交频分复用 + 独立分量分析　；参考：《集美大学》2015年硕士论文

【摘要】：作为4G通信的核心技术之一,正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术具有诸多优点,比如抗频率选择性衰落能力强、频带利用率高、高速数据传输等。虽然经过长期的发展,OFDM的各项关键技术已经逐渐成熟,但是仍然存在一些问题需要改进。本文借助独立分量分析(Independent Component Analysis,ICA)技术,针对OFDM系统频偏和信道估计展开研究。本文的主要研究内容概括如下:首先介绍了本文的研究对象——OFDM系统的基本原理,列出了其优缺点,给出OFDM系统频偏和信道估计的研究现状,对本文涉及到的OFDM系统的关键技术进行了详细的分析说明。其次介绍本论文使用的工具——独立分量分析技术,给出了其定义,总结了独立性的度量方法,并介绍本论文用到的FASTICA和NLRICA两种算法。然后提出利用单通道信号记录来估计OFDM系统频偏的新方法。传统的ICA算法进行频偏估计需要借助多通道信号记录,本文提出的方法只需利用相关检测技术处理单路OFDM信号,获得观测信号向量,通过ICA算法分离出含频偏信息的信号,然后估计OFDM系统的频偏。与传统的频偏估计方法相比较,该方法不需要信道状态信息和辅助信息,不需要额外的带宽,降低了系统实现的复杂度。最后提出了利用共轭先验信息的OFDM系统信道估计方法。对于使用零前缀(zero padding,ZP)的OFDM系统,可将信道矩阵替换成循环矩阵,然后接收端信号左乘FFT矩阵将该循环矩阵对角化,这时使用盲信号分离技术只需要寻找一个对角矩阵,减少了计算量。另外,充分利用对角矩阵的先验信息,在目标函数中增加上述对角矩阵的稀疏性度量,提高了信道估计的效率和准确性。
[Abstract]:As one of the core technologies of 4G communication, orthogonal Frequency Division Multiplexing OFDM (OFDM) technology has many advantages, such as strong anti-frequency selective fading ability, high bandwidth utilization rate, high speed data transmission and so on. Although the key technologies of OFDM have matured over a long period of time, there are still some problems to be improved. In this paper, the frequency offset and channel estimation of OFDM systems are studied by means of independent component analysis (ICA) technique. The main research contents of this paper are summarized as follows: firstly, the basic principle of OFDM system is introduced, its advantages and disadvantages are listed, and the research status of frequency offset and channel estimation in OFDM system is given. The key technology of OFDM system involved in this paper is analyzed and explained in detail. Secondly, the independent component analysis (ICA) technique used in this paper is introduced, its definition is given, the measurement method of independence is summarized, and the FASTICA and NLRICA algorithms used in this thesis are introduced. Then a new method is proposed to estimate the frequency offset of OFDM system using single channel signal recording. The traditional ICA algorithm for frequency offset estimation needs to be recorded by multi-channel signals. The method proposed in this paper only needs to process single channel OFDM signals by using correlation detection technology, and obtain the observation signal vectors. The signals containing frequency offset information are separated by ICA algorithm. Then the frequency offset of OFDM system is estimated. Compared with the traditional frequency offset estimation method, the proposed method does not require channel state information and auxiliary information, and does not require additional bandwidth, thus reducing the complexity of the system implementation. Finally, a channel estimation method for OFDM systems using conjugate prior information is proposed. For a OFDM system using the zero prefix ZP, the channel matrix can be replaced with a cyclic matrix, and then the signal at the receiving end is diagonalized by the left multiplying the FFT matrix. In this case, the blind signal separation technique only needs to find a diagonal matrix. The calculation is reduced. In addition, the priori information of diagonal matrix is fully used to increase the sparsity of the diagonal matrix in the objective function, which improves the efficiency and accuracy of channel estimation.
【学位授予单位】：集美大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN929.53

【共引文献】