【作者】 胡玉杰；

【导师】 李艳萍；

【作者基本信息】 太原理工大学 ， 通信与信息系统， 2008， 硕士

【摘要】 OFDM是一种无线环境下的高速传输技术,该技术的基本原理是将高速的串行数据分解成多路低速率的并行数据,并针对不同的载波分别进行调制。因此通过各个子载波的联合编码,OFDM系统可以具有良好的抗多径衰落和时延弥散的能力,并且保持较高的传输速率。本文主要研究了OFDM通信系统中的信道估计参数问题。首先讨论了OFDM系统信道估计发展现状,然后在分析了其基本原理的前提下,提出了一种改进的OFDM盲信道估计模型,此改进算法的优点在于在循环前缀大于或小于信道阶数两种情况下该算法不用任何变形都可以直接适用。而仿真结果也表明,在循环前缀大于信道阶数的情况下,改进后的算法比文献[32-34]提出的算法收敛速度更快。最后本文在此基础上进一步研究,引入了虚拟子载波技术。这一方面使得算法的适用范围更加完善,在没有循环前缀的情况下依然成立,另一方面可以潜在的提高系统地频带利用率。最后,本文提出的算法没有采用传统的子空间分解方法,即不必求接收信号的二阶统计量,而是直接对接收信号进行分解。仿真结果表明,该算法的实用性比较强,且适用范围的扩大并没有以牺牲大量的系统性能为代价。更多还原

【Abstract】 OFDM is a kind of high-speed wireless transmission technology, which bases on the principle that the high-speed serial data will be broken down into multiple low-speed parallel data, and the parallel data be modulated by exploiting the different carrier modulation. So through the joint coding to all subcarriers,OFDM system can get a good capacity of the anti-multipath fading and the delay diffusion, and maintain a higher transfer rate.This paper have studied the channel estimation parameters of the OFDM systems.Firstly the article discussed the development status quo of channel estimation technology in OFDM systems,and then on the basis of the literature [32-34],a improved OFDM blind channel estimation model is proposed. This method has the advantage that the algorithm still works for OFDM systems when the cyclic prefix is greater than or less than the number of channel bands. The simulation results also show that in the situation that the cyclic prefix is greater than the number of channel bands,the improved algorithm convergence faster than the algorithm mentioned in the literature [32-34].Finally, this article also introducd the virtual subcarrier technology on the base of the improved OFDM channel estimation algorithm. On the hand this connection make the application of the algorithm better in the absence of cyclic prefix, on the other hand it could potentially improve the bandwidth utilization. The algorithm that uses subspace decomposition method does not want the the second-order statistics of the receiving signals, But exploites the receiver signal decomposition directly. Simulation results show that the algorithm is very practical, and in all kinds of circumstances for CP, the performance is excellent.更多还原