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Author : Deepak Garise
Publisher :
ISBN 13 :
Total Pages : 182 pages
Book Rating : 4.:/5 (614 download)
Download or read book Adaptive Channel Estimation Techniques for OFDM Systems in Doppler Channels written by Deepak Garise and published by . This book was released on 2005 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Manoj S. Daniel
Publisher :
ISBN 13 :
Total Pages : 200 pages
Book Rating : 4.:/5 (563 download)
Download or read book Evaluation of Adaptive Channel Estimation Techniques on Impulse Radio Channels written by Manoj S. Daniel and published by . This book was released on 2003 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Lajos Hanzo
Publisher : John Wiley & Sons
ISBN 13 : 0470031379
Total Pages : 430 pages
Book Rating : 4.4/5 (7 download)
Download or read book OFDM and MC-CDMA written by Lajos Hanzo and published by John Wiley & Sons. This book was released on 2007-01-11 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless communications has witnessed a tremendous growth during the past decade and further spectacular enabling technology advances are expected in an effort to render ubiquitous wireless connectivity a reality. Currently, a technical in-depth book on this subject is unavailable, which has a similar detailed exposure of OFDM, MIMO-OFDM and MC-CDMA. A further attraction of the joint treatment of these topics is that it allows the reader to view their design trade-offs in a comparative context. Divided into three main parts: Part I provides a detailed exposure of OFDM designed for employment in various applications Part II is another design alternative applicable in the context of OFDM systems where the channel quality fluctuations observed are averaged out with the aid of frequency-domain spreading codes, which leads to the concept of MC-CDMA Part III discusses how to employ multiple antennas at the base station for the sake of supporting multiple users in the uplink By providing an all-encompassing self-contained treatment this volume will appeal to a wide readership, as it is both an easy-reading textbook and a high-level research monograph.
Download or read book Channel Estimation Techniques for OFDM Systems in Dispersive Time-varying Channels written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coherent modulation is more effective than differential modulation for orthogonal frequency division multiplexing (OFDM) systems requiring high data rate and spectral efficiency. Channel estimation is therefore an integral part of the receiver design. In this thesis, two iterative maximum likelihood based channel estimation algorithms are proposed for an OFDM system in dispersive time-varying channels. A multipath channel model is proposed for OFDM uplink transmission in macrocellular systems. The multipath fading channel is modeled such that the channel state can be determined by estimating the unknown channel parameters. A second-order Taylor series expansion is adopted to simplify the channel estimation problem. Based on the system model, an iterative maximum likelihood based algorithm is first proposed to estimate the discrete-time channel parameters. The mean square error performance of the proposed algorithm is analyzed using a small perturbation technique. Based on a convergence rate analysis, an improved iterative maximum likelihood based channel estimation algorithm is presented using a successive overrelaxation method. Numerical experiments are performed to confirm the theoretical analyses and show the improvement in convergence rate of the improved algorithm.
Author : Xenofon G.. Doukopoulos
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (493 download)
Download or read book Blind Adaptive Channel Estimation in OFDM Systems written by Xenofon G.. Doukopoulos and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jake Hwang
Publisher :
ISBN 13 :
Total Pages : 65 pages
Book Rating : 4.:/5 (613 download)
Download or read book Simplified Channel Estimation Techniques for OFDM Systems with Realistic Indoor Fading Channels written by Jake Hwang and published by . This book was released on 2009 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation deals with the channel estimation techniques for orthogonal frequency division multiplexing (OFDM) systems such as in IEEE 802.11. Although there has been a great amount of research in this area, characterization of typical wireless indoor environments and design of channel estimation schemes that are both robust and practical for such channel conditions have not been thoroughly investigated. It is well known that the minimum mean-square-error (MMSE) estimator provides the best mean-square-error (MSE) performance given a priori knowledge of channel statistics and operating signal-to-noise ratio (SNR). However, the channel statistics are usually unknown and the MMSE estimator has too much computational complexity to be realized in practical systems. In this work, we propose two simple channel estimation techniques: one that is based on modifying the channel correlation matrix from the MMSE estimator and the other one with averaging window based on the LS estimates. We also study the characteristics of several realistic indoor channel models that are of potential use for wireless local area networks (LANs). The first method, namely MMSE-exponential-Rhh, does not depend heavily on the channel statistics and yet offer performance improvement compared to that of the LS estimator. The simulation results also show that the second method, namely averaging window (AW) estimator, provides the best performance at moderate SNR range.
Author : Ali Ramadan M. Ali
Publisher :
ISBN 13 :
Total Pages : 128 pages
Book Rating : 4.:/5 (649 download)
Download or read book Channel Estimation and ICI Cancellation for Adaptive OFDM Systems in Doubly Selective Channels written by Ali Ramadan M. Ali and published by . This book was released on 2010 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Tianze Su
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (973 download)
Download or read book Adaptive Semiblind Channel Estimation for OFDM/OQAM Systems written by Tianze Su and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "In this thesis, we propose and investigate novel adaptive semi-blind channel estimation algorithms for OFDM/OQAM systems. OFDM/OQAM is regarded as a promising alternative to conventional CP-OFDM for multi-carrier modulation since it can provide better spectrum efficiency, albeit at the price of increased complexity. We first formulate a general system model of an OFDM/OQAM transceiver. Based on this model, we review a recently proposed block based semi-blind channel estimation method for OFDM/OQAM systems, known as the sign covariance matrix (SCM) method. This method mainly exploits the higher-order statistical properties of the data at the receiver side but is not well-suited for applications to time-varying channels. Subsequently, to overcome the drawbacks of this block-based technique, we propose adaptive semi-blind channel estimation algorithms for application to OFDM/OQAM. The proposed algorithms consist of an adaptive SCM technique obtained through exponential recursive averaging, as well as several constant modulus algorithms (CMA) for recursive estimation. Although all the adaptive algorithms are designed to deal with time-varying channels, they can also be used for rapid channel acquisition in the case of static or slowly-varying channels. Furthermore, we explore the coherence bandwidth of the channel and make use of this concept to improve the estimation accuracy via a frequency averaging technique that can be combined with the adaptive SCM. Simulation results validate the efficacy of the proposed adaptive estimation algorithms over both time-invariant and varying channels, showing their robustness in terms of convergence speed, tracking capability and residual estimation error in steady-state. In particular, the CMA with recursive least squares (CMA-RLS) updating proves to be the most preferable due to its excellent trade-off between convergence rate and residual error level. The CMA-RLS also offers the best performance in tracking a time-varying channel. In addition, simulation experiments demonstrate the effectiveness of combining the frequency averaging technique with the proposed adaptive SCM algorithm." --
Author : Franz Hlawatsch
Publisher : Academic Press
ISBN 13 : 0080922724
Total Pages : 457 pages
Book Rating : 4.0/5 (89 download)
Download or read book Wireless Communications Over Rapidly Time-Varying Channels written by Franz Hlawatsch and published by Academic Press. This book was released on 2011-05-04 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a result of higher frequencies and increased user mobility, researchers and systems designers are shifting their focus from time-invariant models to channels that vary within a block. Wireless Communications Over Rapidly Time-Varying Channels explains the latest theoretical advances and practical methods to give an understanding of rapidly time varying channels, together with performance trade-offs and potential performance gains, providing the expertise to develop future wireless systems technology. As well as an overview of the issues of developing wireless systems using time-varying channels, the book gives extensive coverage to methods for estimating and equalizing rapidly time-varying channels, including a discussion of training data optimization, as well as providing models and transceiver methods for time-varying ultra-wideband channels. An introduction to time-varying channel models gives in a nutshell the important issues of developing wireless systems technology using time-varying channels Extensive coverage of methods for estimating and equalizing rapidly time-varying channels, including a discussion of training data optimization, enables development of high performance wireless systems Chapters on transceiver design for OFDM and receiver algorithms for MIMO communication channels over time-varying channels, with an emphasis on modern iterative turbo-style architectures, demonstrates how these important technologies can optimize future wireless systems
Author : Lajos Hanzo
Publisher : John Wiley & Sons
ISBN 13 : 0470861800
Total Pages : 1014 pages
Book Rating : 4.4/5 (78 download)
Download or read book OFDM and MC-CDMA for Broadband Multi-User Communications, WLANs and Broadcasting written by Lajos Hanzo and published by John Wiley & Sons. This book was released on 2005-01-28 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal frequency-division multiplexing (OFDM) is a method of digital modulation in which a signal is split into several narrowband channels at different frequencies. CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimising the use of available bandwidth. Multiplexing is sending multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end. Multi-Carrier (MC) CDMA is a combined technique of Direct Sequence (DS) CDMA (Code Division Multiple Access) and OFDM techniques. It applies spreading sequences in the frequency domain. Wireless communications has witnessed a tremendous growth during the past decade and further spectacular enabling technology advances are expected in an effort to render ubiquitous wireless connectivity a reality. This technical in-depth book is unique in its detailed exposure of OFDM, MIMO-OFDM and MC-CDMA. A further attraction of the joint treatment of these topics is that it allows the reader to view their design trade-offs in a comparative context. Divided into three main parts: Part I provides a detailed exposure of OFDM designed for employment in various applications Part II is another design alternative applicable in the context of OFDM systems where the channel quality fluctuations observed are averaged out with the aid of frequency-domain spreading codes, which leads to the concept of MC-CDMA Part III discusses how to employ multiple antennas at the base station for the sake of supporting multiple users in the uplink Portrays the entire body of knowledge currently available on OFDM Provides the first complete treatment of OFDM, MIMO(Multiple Input Multiple Output)-OFDM and MC-CDMA Considers the benefits of channel coding and space time coding in the context of various application examples and features numerous complete system design examples Converts the lessons of Shannon’s information theory into design principles applicable to practical wireless systems Combines the benefits of a textbook with a research monograph where the depth of discussions progressively increase throughout the book This all-encompassing self-contained treatment will appeal to researchers, postgraduate students and academics, practising research and development engineers working for wireless communications and computer networking companies and senior undergraduate students and technical managers.
Author : Wichai Pongwilai
Publisher :
ISBN 13 : 9789744660084
Total Pages : 306 pages
Book Rating : 4.6/5 (6 download)
Download or read book Improved Channel Estimation Techniques for OFDM Systems in Frequency Selective Fading Channels written by Wichai Pongwilai and published by . This book was released on 2004 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Abdulkhalek Mustafa Zatout
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (18 download)
Download or read book Synchronization and Channel Estimation Techniques for OFDM Systems written by Abdulkhalek Mustafa Zatout and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Xibin Han
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (11 download)
Download or read book Channel Estimation Techniques for WCDMA Communication Systems written by Xibin Han and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the study of efficient channel estimation techniques for WCDMA communication systems. Some background material pertaining to wireless multipath propagation and WCDMA systems is first presented. The maximum-likelihood principle based data-aided channel estimation techniques are then investigated, resulting in two new estimation methods using pilot and information symbols. The first method combines the pilot-assisted and the decision-directed estimation schemes, yielding a much better estimation result compared to each of the two schemes alone. The second technique corresponds to an adaptive channel estimation scheme in which a new update mechanism using a variable step-size is proposed. A theoretical analysis of the mean square error of the least mean square (LMS) algorithm is conducted, showing the superiority of a variable step-size update scheme in convergence speed over the conventional constant step-size algorithm. The proposed scheme is not only able to increase the convergence speed but also can decrease the steady-state error of the adaptive estimation filter to a certain degree. The bit-error rate (BER) performance of both downlink and uplink of the WCDMA systems using the proposed channel estimation techniques is evaluated through extensive computer simulations for different mobile velocities, confirming the improved estimation accuracy of the proposed methods for both slow to fast fading channels in comparison with some of the existing techniques (Abstract shortened by UMI.).
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (946 download)
Download or read book A New Approach to Blind Channel Identification for OFDM Systems written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal frequency division multiplexing (OFDM) is, with substantial progress in digital signal processing, becoming an important part of the telecommunications arena. The most appealing feature of OFDM is the simplicity of the receiver design due to the efficiency with which OFDM can cope with the effects of frequency-selective multipath channels. Here, we address the problem of channel estimation for OFDM systems. Exploiting receive antenna diversity, a second-order statistics-based (SOS) blind technique is proposed. Our method differs from the existing SOS-based techniques in that channel estimation is carried out using the frequency domain (i.e., post-FFT) signals whereas existing methods use the time domain signals (i.e., pre-FFT). In the proposed method, channel identifiability is guaranteed regardless of the channels zeros locations, so long as any roots common to all the diversity channels are on the unit circle. Only short data records are required to achieve good performance. For PSK transmission, this method enables channel estimation even from a single OFDM symbol at high SNR. Further, when only a small number of subcarriers can be used for channel estimation because of computational complexity, we determine the optimal set of subcarriers in terms of estimation accuracy.
Author : 張喻斌
Publisher :
ISBN 13 :
Total Pages : 68 pages
Book Rating : 4.:/5 (769 download)
Download or read book Adaptive Channel Estimation for Orthogonal Frequency Division Multiplexing Systems written by 張喻斌 and published by . This book was released on 2003 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Ahmad R.S. Bahai
Publisher : Springer Science & Business Media
ISBN 13 : 030646974X
Total Pages : 224 pages
Book Rating : 4.3/5 (64 download)
Download or read book Multi-Carrier Digital Communications written by Ahmad R.S. Bahai and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-carrier modulation, in particular orthogonal frequency division multiplexing (OFDM), has been successfully applied to a wide variety of digital communications applications for several years. Although OFDM has been chosen as the physical layer standard for a diversity of important systems, the theory, algorithms, and implementation techniques remain subjects of current interest. This book is intended to be a concise summary of the present state of the art of the theory and practice of OFDM technology. This book offers a unified presentation of OFDM theory and high speed and wireless applications. In particular, ADSL, wireless LAN, and digital broadcasting technologies are explained. It is hoped that this book will prove valuable both to developers of such systems, and to researchers and graduate students involved in analysis of digital communications, and will remain a valuable summary of the technology, providing an understanding of new advances as well as the present core technology.
Author : Fulvio Gini
Publisher : Academic Press
ISBN 13 : 0123972248
Total Pages : 1389 pages
Book Rating : 4.1/5 (239 download)
Download or read book Academic Press Library in Signal Processing written by Fulvio Gini and published by Academic Press. This book was released on 2013-09-10 with total page 1389 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second volume, edited and authored by world leading experts, gives a review of the principles, methods and techniques of important and emerging research topics and technologies in communications and radar engineering. With this reference source you will: Quickly grasp a new area of research Understand the underlying principles of a topic and its application Ascertain how a topic relates to other areas and learn of the research issues yet to be resolved Quick tutorial reviews of important and emerging topics of research in array and statistical signal processing Presents core principles and shows their application Reference content on core principles, technologies, algorithms and applications Comprehensive references to journal articles and other literature on which to build further, more specific and detailed knowledge Edited by leading people in the field who, through their reputation, have been able to commission experts to write on a particular topic
