多用户MIMO系统的盲均衡算法研究

发布时间：2018-01-13 22:08

本文关键词：多用户MIMO系统的盲均衡算法研究　出处：《安徽理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：近几年,随着无线通信数据业务需求量的增加,加速了宽带无线通信技术的发展和应用,多用户多输入多输出(Multiple-Input Multiple-Output, MIMO)无线系统中的信号处理技术也越来越引起人们的重视。为消除码间干扰通常采用盲均衡技术进行处理,本文首先研究了单输入多输出系统(Single-Input Multiple-Output, SIMO)中的盲均衡算法,接着研究了单用户MIMO系统盲均衡算法,利用小波变换理论降低信号的自相关性,提高算法的性能,最后研究了正交小波盲均衡技术在多用户MIMO系统中的应用。研究内容包括： 1基于单输入多输出系统的正交小波盲均衡算法为了提高单输入多输出SIMO系统的抗衰落性能及常数模盲均衡算法(CMA)的均衡效果,提出一种基于SIMO系统的正交小波变换盲均衡算法(WT-CMA),用小波变换域对输入信号进行均衡,利用正交小波变换降低输入信号的自相关性。理论分析及计算机仿真结果表明,该算法在SIMO系统中便于实现,与CMA相比具有更优越的性能。 2基于奇异值分解的单用户MIMO系统小波常模盲均衡算法在单用户多输入多输出系统中,如果直接将输出信号送入均衡器,无法实现信道的均衡。本文以矩阵的奇异值理论为数学基础,将单用户MIMO系统与奇异值分解理论及常模算法结合,先将接收信号分解到正交的子空间,经过小波变换后,再对子空间的子信号进行盲均衡处理。在单输入多输出SIMO系统的常数模盲均衡算法的基础上,提出了基于奇异值分解的单用户多输入多输出(MIMO)系统的小波常模盲均衡算法。 3基于多用户MIMO系统的小波盲均衡算法由于多用户多输入多输出无线通信系统信道的复杂性,关于这方面的理论研究稀缺。多用户多输入多输出(MIMO)通信系统的不仅受多径效应及频率选择性衰落信道引起的码间干扰,不同用户之间的信号也会相互干扰严重影响通信效果。为了提高该系统的性能,利用奇异值分解理论,将多用户MIMO系统的信道分解为多个并行的独立信道,再对每个独立的信道分别进行均衡,通过对代价函数的改进,消除信号之间的相互干扰,成功的将小波盲均衡算法应用到了多用户MIMO系统中。理论分析与计算机仿真结果显示,该算法能够获得较快的收敛速度及较低的稳态误差,且收敛后眼图较为清晰,证明该方法的可行性及有效性。
[Abstract]:In recent years, with the increasing demand for wireless communication data services, the development and application of broadband wireless communication technology has been accelerated. Multiple-Input Multiple-Output. The signal processing technology in MIMO-based wireless systems has attracted more and more attention. Blind equalization technology is usually used to eliminate inter-symbol interference (ISI). In this paper, we first study the blind equalization algorithm for single-input multiple-output (SIMO) systems. Then the blind equalization algorithm of single user MIMO system is studied. Wavelet transform theory is used to reduce the autocorrelation of signal and improve the performance of the algorithm. Finally, the application of orthogonal wavelet blind equalization in multi-user MIMO systems is studied. 1. Orthogonal wavelet blind equalization algorithm based on single input multi-output system In order to improve the anti-fading performance of single-input multiple-output (SIMO) system and the equalization effect of constant modulus blind equalization algorithm (CMA). A blind equalization algorithm of orthogonal wavelet transform based on SIMO system is proposed. The input signal is equalized in wavelet transform domain. Orthogonal wavelet transform is used to reduce the autocorrelation of input signal. Theoretical analysis and computer simulation results show that the algorithm is easy to implement in SIMO system and has better performance than CMA. A Wavelet constant Modulus Blind Equalization algorithm for Single-user MIMO Systems based on singular value decomposition In a single-user multi-input multi-output system, if the output signal is sent directly to the equalizer, the channel equalization can not be realized. In this paper, the singular value theory of the matrix is taken as the mathematical basis. The single-user MIMO system is combined with singular value decomposition theory and constant modulus algorithm. The received signal is decomposed into orthogonal subspace after wavelet transform. Then the subsignals in the subspace are processed by blind equalization, which is based on the constant modulus blind equalization algorithm of single-input multi-output SIMO systems. A wavelet constant modulus blind equalization algorithm based on singular value decomposition (SVD) for single-user multi-input-multiple-output (Mimo) systems is proposed. Wavelet Blind Equalization algorithm based on Multi-user MIMO system Because of the complexity of multi-user multi-input and multi-output wireless communication system channel. Theoretical research on this aspect is scarce. Multi-user multi-input and multi-output MIMO-communication systems are not only caused by the multi-path effect and frequency selective fading channel inter-symbol interference. In order to improve the performance of the system, singular value decomposition (SVD) theory is used to improve the performance of the system. The channel of multi-user MIMO system is decomposed into several parallel independent channels, and then each independent channel is equalized separately, and the mutual interference between signals is eliminated by improving the cost function. The wavelet blind equalization algorithm is successfully applied to the multi-user MIMO system. The theoretical analysis and computer simulation results show that the algorithm can achieve faster convergence speed and lower steady-state error. The convergent eye diagram is clear, which proves the feasibility and effectiveness of the method.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.5

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