EBookClubs

Read Books & Download eBooks Full Online

EBookClubs

Read Books & Download eBooks Full Online

Book Semi Blind Carrier Frequency Offset Estimation and Channel Equalization

Download or read book Semi Blind Carrier Frequency Offset Estimation and Channel Equalization written by Yufei Jiang and published by Springer. This book was released on 2015-12-01 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: This SpringerBrief investigates the performance of semi-blind independent component analysis (ICA) based equalization and carrier frequency offset estimation approaches (CFO) for a number of orthogonal frequency division multiplexing (OFDM) based wireless communication systems. It provides a comprehensive overview of the challenges of channel equalization and frequency synchronization for different wireless systems. The authors present the wireless communication channel and system models. Key existing CFO estimation methods are reviewed, along with a number of the training based and non-training based (blind) channel estimation methods. This is followed by a study of ICA and its applications to OFDM-based wireless communication systems. Later chapters provide a detailed description of recent research on semi-blind CFO estimation and ICA based equalization approaches for various wireless communication systems including multiple-input multiple-output (MIMO) OFDM and coordinated multipoint (CoMP) systems. Semi-blind CFO estimation and equalization structures provide a spectrum-efficient and high-performance solution for high speed wireless communications. This book is suitable for postgraduate students, researchers or professionals in the area of wireless communications.

Book Intercarrier Interference Reduction and Channel Estimation in OFDM Systems

Download or read book Intercarrier Interference Reduction and Channel Estimation in OFDM Systems written by Yihai Zhang and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: With the increasing demand for more wireless multimedia applications, it is desired to design a wireless system with higher data rate. Furthermore, the frequency spectrum has becomea limited and valuable resource, making it necessary to utilize the available spectrum efficiently and coexist with other wireless systems. Orthogonal frequency division multiplexing (OFDM)modulation is widely used in communication systems to meet the demand for ever increasing data rates. The major advantage of OFDM over single-carrier transmission is its ability to deal with severe channel conditions without complex equalization. However, OFDM systems suffer from a high peak to average power ratio, and they are sensitive to carrier frequency offset and Doppler spread. This dissertation first focuses on the development of intercarrier interference (ICI) reduction and signal detection algorithms for OFDM systems over time-varying channels. Several ICI reduction algorithms are proposed for OFDM systems over doubly-selective channels. The OFDM ICI reduction problem over time-varying channels is formulated as a combinatorial optimization problem based on the maximum likelihood (ML)criterion. First, two relaxation methods are utilized to convert the ICI reduction problem into convex quadratic programming (QP) problems. Next, a low complexity ICI reduction algorithm applicable to $M$-QAM signal constellations for OFDM systems is proposed. This formulates the ICI reduction problem as a QP problem with non-convex constraints. A successive method is then utilized to deduce a sequence ofreduced-size QP problems. For the proposed algorithms, the QPproblems are solved by limiting the search in the 2-dimensional subspace spanned by its steepest-descent and Newton directions to reduce the computational complexity. Furthermore, a low-bit descent search (LBDS) is employed to improve the system performance. Performance results are given to demonstrate that the proposed ICI reduction algorithms provide excellent performance with reasonable computational complexity. A low complexity joint semiblind detection algorithm based on the channel correlation and noisevariance is proposed which does not require channel state information. The detection problem is relaxed to a continuous non-convex quadratic programming problem. Then an iterative method is utilized to deduce a sequence of reduced-size quadratic programming problems. A LBDS method is also employed to improve the solution of the derived QP problems. Results are given which demonstrate that the proposed algorithm provides similar performance with lower computational complexity compared to that of a sphere decoder. A major challenge to OFDM systems is how to obtain accurate channel state information for coherent detection of the transmitted signals. Thus several channel estimation algorithms are proposed for OFDM systems over time-invariant channels. A channel estimation method is developed to utilize the noncircularity of the input signals to obtain an estimate of the channel coefficients ...

Book Channel Estimation and Data Detection of OFDM Systems Under Unknown Channel Order Doppler Frequency

Download or read book Channel Estimation and Data Detection of OFDM Systems Under Unknown Channel Order Doppler Frequency written by Rui Min (M. Phil.) and published by . This book was released on 2011 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Design of Channel Estimation and Equalization for OFDM Systems

Download or read book Design of Channel Estimation and Equalization for OFDM Systems written by Ali Salah Mahdi and published by LAP Lambert Academic Publishing. This book was released on 2015-01-20 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal Frequency Division Multiplexing (OFDM) system is one of the multicarrier techniques which is robust against Inter-symbol-Interference, multipath fading and very easy to apply in transmitters by using inverse fast Fourier transform IFFT and at the receivers by using fast Fourier transform FFT. In a communication system, channel estimation is very important issue for the data detection. In coherent detection, one of the popular techniques is to use pilot tones as a reference signal in OFDM symbols. In the comb-type pilot tones insertion, pilot tones are inserted into each OFDM symbols, but inserting a large number of pilot tones will lead to channel capacity reduction or bandwidth expansion [1-2]. In this work, to overcome this transmission loss, a modified least square (ModLS) algorithm for fast time varying wireless channel at comb-type pilot arrangement in QAM signals for OFDM system is proposed. The simulation results obtained from the proposed algorithm showed a good performance in noisy wireless channels. In addition, it has been compared with least square (LS) algorithm in different signal to noise ratios and different channel tabs.

Book Carrier Frequency Offset Estimation for Multicarrier Communications

Download or read book Carrier Frequency Offset Estimation for Multicarrier Communications written by Cheng Li and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Carrier Frequency Offset Estimation for Multicarrier Communications" by Cheng, Li, 李鋮, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Carrier Frequency Offset Estimation for Multicarrier Communications Submitted by Li Cheng For the degree of Master of Philosophy at the University of Hong Kong in Feb., 2004 Multicarrier (MC) transmission is a promising technology in broadband wireless access involving high-throughput data transmission. MC communications are advantageous over single-carrier transmission in dealing with inter-symbol interference (ISI) due to the channel delay spread. However, MC communications also have certain drawbacks, including the vulnerability to carrier frequency offset (CFO) arising from the difference of oscillator frequencies between the transmitter and the receiver or from the Doppler shift. The performance of MC systems degrades severely even if the CFO is a small fraction of the subcarrier spacing. Therefore, correction of CFO is very important for MC communications. This thesis considers two variants of MC technologies, OFDM and MC-CDMA, and investigates CFO estimation for both systems. For OFDM systems, a semi-blind CFO estimation algorithm utilizing the embedded pilot tones, which are primarily used for channel estimation, is proposed for slowly-varying multipath channels. The algorithm is bandwidth efficient because it requires no training symbols. It is also demonstrated that the proposed algorithm can be regarded as the general form of the virtual-carrier-based CFO estimation algorithm previously proposed in the literature. For the purpose of practical implementation, a reduced-complexity estimator is also developed. It offers a tradeoff between estimation accuracy and implementation complexity. It is shown by simulation results that the proposed algorithm outperforms the cyclic-prefix-based algorithm in terms of the estimated CFO mean-square error performance. For MC- CDMA systems, a blind CFO estimator is proposed for the downlink transmission, where all users' signals are synchronously transmitted. The estimation scheme consists of two stages: feed-forward acquisition and error-feedback data-directed tracking. The acquisition stage is implemented utilizing the orthogonality among spreading codes and it is capable of bringing the CFO as large as the signal bandwidth to a small value. The residual CFO is refined by the tracking stage, which estimates the CFO and users' data simultaneously based on the maximum likelihood criterion. A reduced-complexity estimator based on the zero-padding FFT technique is also developed to reduce the implementation complexity. The performance of the proposed algorithm is investigated by extensive computer simulations. DOI: 10.5353/th_b2972533 Subjects: Signal processing - Digital techniques - Mathematics Multiplexing Wireless communication systems

Book OFDM Baseband Receiver Design for Wireless Communications

Download or read book OFDM Baseband Receiver Design for Wireless Communications written by Tzi-Dar Chiueh and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal frequency-division multiplexing (OFDM) access schemes are becoming more prevalent among cellular and wireless broadband systems, accelerating the need for smaller, more energy efficient receiver solutions. Up to now the majority of OFDM texts have dealt with signal processing aspects. To address the current gap in OFDM integrated circuit (IC) instruction, Chiueh and Tsai have produced this timely text on baseband design. OFDM Baseband Receiver Design for Wireless Communications covers the gamut of OFDM technology, from theories and algorithms to architectures and circuits. Chiueh and Tsai give a concise yet comprehensive look at digital communications fundamentals before explaining modulation and signal processing algorithms in OFDM receivers. Moreover, the authors give detailed treatment of hardware issues -- from design methodology to physical IC implementation. Closes the gap between OFDM theory and implementation Enables the reader to transfer communication receiver concepts into hardware design wireless receivers with acceptable implementation loss achieve low-power designs Contains numerous figures to illustrate techniques Features concrete design examples of MC-CDMA systems and cognitive radio applications Presents theoretical discussions that focus on concepts rather than mathematical derivation Provides a much-needed single source of material from numerous papers Based on course materials for a class in digital communication IC design, this book is ideal for advanced undergraduate or post-graduate students from either VLSI design or signal processing backgrounds. New and experienced engineers in industry working on algorithms or hardware for wireless communications devices will also find this book to be a key reference.

Book Joint OFDM Symbol Detection and Channel Estimation Over Doubly Selective Channels

Download or read book Joint OFDM Symbol Detection and Channel Estimation Over Doubly Selective Channels written by Yi Wang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Orthogonal Frequency Division Multiplexing (OFDM) is a promising technique for high data rate transmission, that is widely used in modern wireless communication systems because of its good performance over frequency selective channels. However OFDM systems are sensitive to channel time variation resulting in Inter-Carrier Interference (ICI), that without suitable detection methods can degrade performance. Channel State Information (CSI) is essential to various OFDM data detection schemes and its acquisition is a critical factor, in particular over time-varying channels. This work considers a technique for integrating the Kalman filter channel estimation with a version of Sphere Decoding (SD) adapted to OFDM detection. By modelling the OFDM system in frequency domain as a Multiple Input Multiple Output (MIMO) system, we derive a powerful SD technique for data detection. By approximating the channel matrix as banded, we are able to maintain a feasible complexity for SD and deliver competitive performance when compared to other existing scheme. For acquisition of CSI, the Basis Expansion (BE) method is used to model the time-varying channels and a Kalman filter is constructed for tracking. The Kalman filter employs decision-feedback from the SD, requiring only a low pilot symbol density, and hence improves bandwidth efficiency. The performance of this scheme is evaluated by Monte-Carlo computer simulations. Results show that compared with competing algorithm, this scheme provides performance gains. When it is used over moderate time-varying LTE channels, this scheme shows good performance even in the presence of carrier phase noise. " --

Book Multi carrier Techniques for Broadband Wireless Communications

Download or read book Multi carrier Techniques for Broadband Wireless Communications written by Man-On Pun and published by World Scientific. This book was released on 2007 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-Carrier Techniques for Broadband Wireless Communications provides an accessible introduction to OFDM-based systems from a signal processing perspective. The first part presents a concise treatment of some fundamental concepts related to wireless communications and multicarrier systems, while the second offers a comprehensive survey of recent developments on a variety of critical design issues. These include synchronization techniques, channel estimation methods, adaptive resource allocation and practical schemes for reducing the peak-to-average power ratio of the transmitted waveform.

Book Carrier Frequency Offset Estimation for OFDM Systems Using Subspace based Methods

Download or read book Carrier Frequency Offset Estimation for OFDM Systems Using Subspace based Methods written by 戴尉任 and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Multi Carrier Digital Communications

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.

Book Improved Synchronization and Channel Estimation Methods for Communication System

Download or read book Improved Synchronization and Channel Estimation Methods for Communication System written by Hui Jin and published by . This book was released on 2004 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: