共查询到20条相似文献,搜索用时 46 毫秒
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全球微波互联接入(WIMAX,Worldwide Interoperability for Microwave AccesS)系统采用正交频分复用技术实现无线宽带接入,信道估计是WIMAX系统的关键技术。这里主要研究了WIMAX系统信道估计中的内插算法,包括线性内插、二阶内插、DFT内插、DCT内插和幅度相位内插等算法,分析并比较了不同内插算法在各种SUI信道中对系统性能的影响,仿真结果表明,在视距信道中,二阶内插以及幅度相位内插算法性能较好;在非视距信道中,DCT-II内插和二阶内插算法性能较好。综合而言,二阶内插算法以增加适当复杂度的代价在各种信道中均获得了较好的性能,推荐采用。 相似文献
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介绍MIMO-OFDM系统中几种基于导频的信道估计方法。首先研究了单天线OFDM系统的信道估计算法。一方面重点关注三种估计准则的原理,仿真表明LMMSE准则具有最佳的性能;另一方面介绍了几种插值的方法用来恢复非导频处的信道信息。 相似文献
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基于训练序列的信道估计方法在慢衰落信道中呈现出较好的性能,但是这种方法不适用于快衰落环境,为了能够及时跟踪信道的变化,通常采用基于导频符号的信道估计方法。将针对采用连续传输方式的MIMO—OFDM系统,讨论基于导频符号的信道估计方法并进行了计算机仿真。 相似文献
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正交频分复用(OFDM,Orthogonal Frequency Division Multiplexing)技术是长期演进(LTE,Long Term Evolution)的核心技术之一.目前,基于导频的信道估计是OFDM系统中信道估计的常用方式.在基于导频的信道估计方式下,结合LS估计算法提出了一种下向插值算法(DWI).在LTE信道模型及导频结构下,通过MATLAB仿真工具,将该算法和现有各种算法的性能进行了比较和分析.仿真结果表明,使用结合LS估计算法和DWI算法的OFDM系统信道估计机制,具有复杂度低、易于实现的优点. 相似文献
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通过介绍UWB技术的发展现状,着重阐述了MB-OFDM UWB通信系统的物理层帧结构和信道模型。在分析最小二乘(LS)信道估计算法和基于快速傅里叶变换(FFT)信道估计算法的基础上,针对MB-OFDM UWB信号帧结构特征提出了一种基于FFT变换和Hannan-Quinn(HQ)准则的改进算法,即FFT-HQ信道估计算法。该文也提出了一种基于信道估计的自适应均衡算法,利用仿真可以看出此均衡算法在性能上优于传统的基于LS算法调整均衡器系数的方法。 相似文献
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MPSK调制系统中的自适应信道估计 总被引:1,自引:0,他引:1
本文研究了在MPSK调制方式下,不发送训练序列的商接判决自适应信道估计问题。为提高信道估计性能,提出采用软判决鉴相估值来调整加权最小均方(WLMS)和加权递归最小二乘(WRLS)自适应算法中的权值来进行信道估计,并研究了改进的软判决WRLS算法。结果表明,软判决加权LMS算法比一般LMS性能有很大提高,改进的软判决WRLS算法估计性能优于WRLS算法。 相似文献
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提出了OFDM通信系统中一种新型自适应信道估计方法。利用信道冲激响应的最重要分量,该自适应信道估计方法能有效降低子载波间干扰和高斯白噪声的影响。根据性能仿真结果比较,本方法的MSE和BElK结果优于变换域插值、时域插值。 相似文献
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传统方法压缩感知算法截取训练序列最后未被数据干扰固定部分作为观测矩阵,该方法为了抵抗最差的信道而浪费了大量的可用观测数据。在此基础上提出了一种自适应压缩感知的信道估计算法,首先对训练序列进行自适应检测,得到整个未受干扰的观测矩阵,再用压缩感知算法计算信道估计。仿真结果表明,这种基于自适应压缩感知的信道估计算法大幅提高了信道估计的准确性。 相似文献
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本文提出了4G OFDM移动通信系统中一种新型的自适应信道估计方法.利用信道冲激响应的最重要分量,本自适应信道估计方法能有效地降低子载波间干扰和高斯白噪声的影响.根据性能仿真结果比较,本方法在MSE、BER上表现优于变换域插值、时域插值方法. 相似文献
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主要研究了MIMO-OFDM系统中快速时变信道的信道估计问题,将3种自适应信道估计算法: RLS,QRD-RLS,IQRD-RLS,应用于快速时变信道进行比较研究,并对其进行计算机仿真。仿真结果表明,3种算法性能相似,其中,QRD-RLS和IQRD-RLS算法的收敛速度要快于RLS算法,对于实时系统而言,这两种算法的效率更高。因此,QRD-RLS和IQRD-RIS算法更适合于快速时变信道。 相似文献
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针对移动WiMAX下行系统中导频个数少且分配不均匀导致的边缘效应问题,提出了一种基于奇异值分解(SVD)的快速傅里叶变换(F下T)内插信道估计方法.该方法首先得到每个符号实际分配导频处的最小二乘信道频响估计,当前符号在相邻符号实际分配导频处的信道频响由相邻符号信道频响线性内插得到;然后,将上述信道估计值合并且按子载波索... 相似文献
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In this paper, chip-level adaptive channel estimation has been explored by using LMS algorithm for wideband CDMA channel estimation.
The expression for the optimum step-size is modified for fading channel estimation problem. In addition, a new method is proposed
to obtain channel estimates with known pilot symbols which is found to give better results than other methods. For slow fading
channels, like pedestrian channel, LMS estimator with no update mode is found to give satisfactory results. For fast fading
channels, like vehicular channel, a common decision directed technique of channel estimation is modified to be used at chip-level
in the downlink (DL). A novel despreader-respreader based channel estimator has been proposed to obtain uplink channel estimates
at chip level which resolves the deficiencies of conventional methods. The performance of Rake receiver with proposed channel
estimation schemes for IMT-DS system – a 3G mobile communication standard – is evaluated in terms of BER.
S. Faisal A. Shah received the B.S. degree from NED University of Engineering and Technology, Karachi, Pakistan, in 1998 and the M.S. degree
from King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia, in 2001, both in Electrical Engineering. From
2001 to 2004, he was a Lecturer in Electrical & Electronics Engineering Department, University of Sharjah, UAE. In September
2004, he joined the Electrical and Computer Engineering Department of University of Minnesota, USA, as a research assistant
where he is currently pursuing the Ph.D. degree in Electrical Engineering.
His research interests include ultra-wideband communication systems, adaptive signal processing and its application to wireless
communication systems.
Asrar U.H. Sheikh graduated from the University of Engineering and Technology, Lahore, Pakistan with first class honours and received his M.Sc.
and Ph.D. degrees from the University of Birmingham, England, in 1966 and 1969 respectively. After completing teaching assignments
in several countries, he returned to Birmingham as a Research Fellow in 1975. He worked at Carleton University from 1981 to
1997, first as Associate Professor and later as a Professor and Associate Chairman for Graduate Studies. He was the Founder
Director of PCS Research Laboratory at Carleton University. Before taking position of Bugshan/Bell Lab Chair in Telecommunications
at King Fahd University of Petroleum and Minerals in April 2000, he was a Professor and Associate Head of the Department of
Electronic and Information Engineering at Hong Kong Polytechnic University, where he was founding director of Wireless Information
Systems Research (WISR) Centre. At KFUPM he established Telecommunications Research Laboratory.
Professor Sheikh is the author of a recently published book, Wireless Communications - Theory & Techniques published by Kluwer Academic Publishers, Orwell, Mass., USA. He has published over 230 papers in international journals and
conference proceedings. He also authored or co-authored 30 technical reports. Dr. Sheikh is a co-recipient of Paul Adorian
Premium from IERE (London) for his work on impulsive noise characterization. He was awarded teaching achievement awards in
1984 and 1986, and Research Achievement Award in 1994, all by Carleton University.
Dr. Sheikh is actively involved in several international conferences mainly as a member of Technical Program Committees. He
has organized and chaired many technical sessions at several international conferences. He Chaired the Technical Program of
VTC'98. He is an editor of IEEE Transaction on Wireless Communications, a Technical Associate Editor of IEEE Communication
Magazine. He is on the Editorial Board of Wireless Personal Communications, and Wireless Communications and Mobile Computing.
He was a co-guest editor of the Special Issue of WPC on Interference. Dr. Sheikh is also on the reviewer panels of many IEEE
and IEE Transactions and Journals.
Dr. Sheikh has been consultant to many private companies and government agencies. His current interests are in signal processing
in communications, mitigation of interference, spread spectrum and 3G and beyond systems. His other interests include helping
developing countries in education and research. He had assignments under UNDP's sustained Development Program. He is a Fellow
of the IEEE and a Fellow of the IEE. Dr. Sheikh is listed in Marquis Who's Whos in the world and Who's Who in Science and
Engineering. 相似文献
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OFDM系统中基于变换域的信道估计 总被引:1,自引:0,他引:1
研究了正交频分复用(OFDM,orthogonal frequency division multiplexing)系统中基于变换域补零的插值方法,深入分析了基于离散余弦变换(DCT)的插值法,利用DCT的能量压缩特性,能有效消除传统基于离散傅里叶变换(DFT,Discrete Fourier Transform)估计算法在信道延时不是采样周期整数倍时产生的频谱能量泄露的问题。针对如何降低导频信道响应估计值中的噪声分量,提出了一种改进的方法,设计了一种适用于DCT变换域的滤波器,通过仿真系统参数变化对改进算法性能的影响,分析和验证了改进算法的有效性。 相似文献