Download or read book Iterative Decoding with Imperfect Channel Estimation for Wireless Systems written by Yibo Zhou and published by . This book was released on 2006 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiple input Multiple output Wireless System Designs with Imperfect Channel Knowledge written by Minhua Ding and published by . This book was released on 2008 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Empowered by linear precoding and decoding, a spatially multiplexed multiple-input multiple-output (MIMO) system becomes a convenient framework to offer high data rate, diversity and interference management. While most of the current precoding/decoding designs have assumed perfect channel state information (CSI) at the receiver, and sometimes even at the transmitter, in this thesis we design the precoder and decoder with imperfect CSI at both the transmit and the receive sides, and investigate the joint impact of channel estimation errors and channel correlation on system structure and performance. The mean-square error (MSE) related performance metrics are used as the design criteria. We begin with the minimum total MSE precoding/decoding design for a single-user MIMO system assuming imperfect CSI at both ends. Here the CSI includes the channel estimate and channel correlation information. The structures of the optimum precoder and decoder are determined. Compared to the perfect CSI case, linear filters are added to the transceiver structure to improve system robustness against imperfect CSI. The effects of channel estimation error and channel correlation are quantified by simulations. With imperfect CSI at both ends, the exact capacity expression for a single-user MIMO channel is difficult to obtain. Instead, a tight capacity lower-bound is used for system design. The optimum structure of the transmit covariance matrix for the lower-bound has not been found in the existing literature. By transforming the transmitter design into a joint precoding/decoding design problem, we derive the expression of the optimum transmit covariance matrix. The close relationship between the maximum mutual information design and the minimum total MSE design is also discovered assuming imperfect CSI. For robust multiuser MIMO communications, minimum average sum MSE transceiver (precoder-decoder pairs) design problems are formulated for both the uplink and the downlink, assuming imperfect channel estimation and channel correlation at the base station (BS). We propose improved iterative algorithms based on the associated Karush-Kuhn-Tucker (KKT) conditions. Under the assumption of imperfect CSI, an uplink--downlink duality in average sum MSE is proved. As an alternative for the uplink optimization, a sequential semidefinite programming (SDP) method is proposed. Simulation results are provided to corroborate the analysis.

Download or read book Iterative Estimation and Decoding for Channels with Memory written by Joseph Hyukjoon Kang and published by . This book was released on 1999 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wireless Channel Estimation With Applications to Secret Key Generation written by Alireza Movahedian and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research investigates techniques for iterative channel estimation to maximize channel capacity and communication security. The contributions of this dissertation are as follows: i) An accurate, low-complexity approach to pilot-assisted fast-fading channel estimation for single-carrier modulation with a turbo equalizer and a decoder is proposed. The channel is estimated using a Kalman filter (KF) followed by a zero-phase filter (ZPF) as a smoother. The combination of the ZPF with the KF of the channel estimator makes it possible to reduce the estimation error to near the Wiener bound. ii) A new semi-blind channel estimation technique is introduced for multiple-input-multiple-output channels. Once the channel is estimated using a few pilots, a low-order KF is employed to progressively predict the channel gains for the upcoming blocks. iii) The capacity of radio channels is investigated when iterative channel estimation, data detection, and decoding are employed. By taking the uncertainty in decoded data bits into account, the channel Linear Minimum Mean Square Error (LMMSE) estimator of an iterative receiver with a given pilot ratio is obtained. The derived error value is then used to derive a bound on capacity. It is shown that in slow fading channels, iterative processing provides only a marginal advantage over non-iterative approach to channel estimation. Knowing the capacity gain from iterative processing versus purely pilot-based channel estimation helps a designer to compare the performance of an iterative receiver against a non-iterative one and select the best balance between performance and cost.iv) A Radio channel is characterized by random parameters which can be used to generate shared secret keys by the communicating parties when the channel is estimated. This research studies upper bounds on the rate of the secret keys extractable from iteratively estimated channels. Various realistic scenarios are considered where the transmission is half-duplex and/or the channel is sampled under the Nyquist rate.The effect of channel sampling interval, fading rate and noise on the key rate is demonstrated. The results of this research can be beneficial for the design and analysis of reliable and secure mobile wireless systems.

Download or read book Iterative Decoding for Trellis Based Codes in Wireless Communications written by Huijun Chen and published by . This book was released on 2008 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this dissertation, we focus on three issues of the trellis based iterative decoding: First, the complexity issue of Turbo code is considered. We propose a constrained iterative decoder to reduce the decoding complexity. An additional interleaver is introduced at the encoder. At the decoder, we first use Cyclic Redundance Code (CRC) to detect which bits are already correctly decoded during early iterations. With knowledge of the positions of these correct bits, the constrained decoding algorithm is designed to reduce the number of the state transitions in the component code trellis and help the decoding of other bits in later iterations. In this way, the constrained iterative decoder achieves significant complexity reduction and still satisfying performance. Second, the iterative decoding algorithm is redesigned for Turbo code implemented Distributed Source Coding (DSC). When used in DSC, the Turbo decoder encounters a combined Binary Symmetric Channel (BSC) and Addictive White Gaussian Noise (AWGN) distortion. The existing iterative decoding algorithm based on AWGN distortion assumption causes performance degradation. By redefining the channel reliability values, the modified iterative decoding algorithm matches the BSC-AWGN scenario well and improves the performance. Third, we propose a reliable source transmission coding and decoding scheme. A serially concatenated source and space time modulated coding structure is used. Variable Length Code (VLC) with error resilient capability is adopted at the application layer. Space Time Trellis Code (STTC) is used to provide high bandwidth efficiency at the physical layer. An iterative joint source space time decoder is designed including the symbol level space time Maximum A Posteriori (MAP) decoder, the bit level VLC MAP decoder and the Viterbi VLC decoder. Critical issues such as STTC MAP algorithm with nonseparable systematic information, VLC MAP algorithm in absence of channel output, VLC Viterbi algorithm based on the bit level trellis and extrinsic information conversion and exchange between bit domain and symbol domain are addressed. The decoding performance of different frame sizes and different component VLCs and STTCs, the rate allocation between the source code and the space time code and the performance in presence of channel estimation errors are discussed in this dissertation.

Download or read book Iterative sic Channel Estimation for Wireless Communications written by and published by . This book was released on 2006 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radio Communications written by Alessandro Bazzi and published by BoD – Books on Demand. This book was released on 2010-04-01 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks.

Download or read book Advanced Wireless Communications written by Savo G. Glisic and published by John Wiley & Sons. This book was released on 2007-06-13 with total page 890 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fully revised and updated version of the successful "AdvancedWireless Communications" Wireless communications continue to attract the attention ofboth research community and industry. Since the first edition waspublished significant research and industry activities have broughtthe fourth generation (4G) of wireless communications systemscloser to implementation and standardization. "Advanced Wireless Communications" continues to provide acomparative study of enabling technologies for 4G. This secondedition has been revised and updated and now includes additionalinformation on the components of common air interface, includingthe area of space time coding , multicarrier modulation especiallyOFDM, MIMO, cognitive radio and cooperative transmission. Ideal for students and engineers in research and development inthe field of wireless communications, the second edition ofAdvanced Wireless Communications also gives an understanding tocurrent approaches for engineers in telecomm operators, governmentand regulatory institutions. New features include: Brand new chapter covering linear precoding in MIMO channelsbased on convex optimization theory. Material based on game theory modelling encompassing problemsof adjacent cell interference, flexible spectra sharing andcooperation between the nodes in ad hoc networks. Presents and discusses the latest schemes for interferencesuppression in ultra wide band (UWB) cognitive systems. Discusses the cooperative transmission and more details onpositioning.

Download or read book Space Time Coding written by Md Anisul Karim and published by . This book was released on 2007 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Iterative Joint Decoding and Channel Estimation on a Two state Gaussian Channel written by and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Iterative Detection for Wireless Communications written by Asri Shaheem and published by . This book was released on 2008 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] The transmission of digital information over a wireless communication channel gives rise to a number of issues which can detract from the system performance. Propagation effects such as multipath fading and intersymbol interference (ISI) can result in significant performance degradation. Recent developments in the field of iterative detection have led to a number of powerful strategies that can be effective in mitigating the detrimental effects of wireless channels. In this thesis, iterative detection is considered for use in two distinct areas of wireless communications. The first considers the iterative decoding of concatenated block codes over slow flat fading wireless channels, while the second considers the problem of detection for a coded communications system transmitting over highly-dispersive frequency-selective wireless channels. The iterative decoding of concatenated codes over slow flat fading channels with coherent signalling requires knowledge of the fading amplitudes, known as the channel state information (CSI). The CSI is combined with statistical knowledge of the channel to form channel reliability metrics for use in the iterative decoding algorithm. When the CSI is unknown to the receiver, the existing literature suggests the use of simple approximations to the channel reliability metric. However, these works generally consider low rate concatenated codes with strong error correcting capabilities. In some situations, the error correcting capability of the channel code must be traded for other requirements, such as higher spectral efficiency, lower end-to-end latency and lower hardware cost. ... In particular, when the error correcting capabilities of the concatenated code is weak, the conventional metrics are observed to fail, whereas the proposed metrics are shown to perform well regardless of the error correcting capabilities of the code. The effects of ISI caused by a frequency-selective wireless channel environment can also be mitigated using iterative detection. When the channel can be viewed as a finite impulse response (FIR) filter, the state-of-the-art iterative receiver is the maximum a posteriori probability (MAP) based turbo equaliser. However, the complexity of this receiver's MAP equaliser increases exponentially with the length of the FIR channel. Consequently, this scheme is restricted for use in systems where the channel length is relatively short. In this thesis, the use of a channel shortening prefilter in conjunction with the MAP-based turbo equaliser is considered in order to allow its use with arbitrarily long channels. The prefilter shortens the effective channel, thereby reducing the number of equaliser states. A consequence of channel shortening is that residual ISI appears at the input to the turbo equaliser and the noise becomes coloured. In order to account for the ensuing performance loss, two simple enhancements to the scheme are proposed. The first is a feedback path which is used to cancel residual ISI, based on decisions from past iterations. The second is the use of a carefully selected value for the variance of the noise assumed by the MAP-based turbo equaliser. Simulations are performed over a number of highly dispersive channels and it is shown that the proposed enhancements result in considerable performance improvements. Moreover, these performance benefits are achieved with very little additional complexity with respect to the unmodified channel shortened turbo equaliser.

Download or read book Baseband Receiver Design for Wireless MIMO OFDM Communications written by Tzi-Dar Chiueh and published by John Wiley & Sons. This book was released on 2012-04-24 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Second Edition of OFDM Baseband Receiver Design for Wirless Communications, this book expands on the earlier edition with enhanced coverage of MIMO techniques, additional baseband algorithms, and more IC design examples. The authors cover the full range of OFDM technology, from theories and algorithms to architectures and circuits. The book gives a concise yet comprehensive look at digital communication fundamentals before explaining signal processing algorithms in receivers. The authors give detailed treatment of hardware issues - from architecture to IC implementation. Links OFDM and MIMO theory with hardware implementation Enables the reader to transfer communication received concepts into hardware; design wireless receivers with acceptable implemntation loss; achieve low-power designs Covers the latest standards, such as DVB-T2, WiMax, LTE and LTE-A Includes more baseband algorithms, like soft-decoding algorithms such as BCJR and SOVA Expanded treatment of channel models, detection algorithms and MIMO techniques Features concrete design examples of WiMAX systems and cognitive radio apllications Companion website with lecture slides for instructors Based on materials developed for a course in digital communication IC design, this book is ideal for graduate students and researchers in VLSI design, wireless communications, and communications signal processing. Practicing engineers working on algorithms or hardware for wireless communications devices will also find this to be a key reference.

Download or read book Advanced Wireless Communications and Internet written by Savo G. Glisic and published by John Wiley & Sons. This book was released on 2011-05-03 with total page 1025 pages. Available in PDF, EPUB and Kindle. Book excerpt: ADVANCED WIRELESS COMMUNICATIONS AND INTERNET THIRD EDITION ADVANCED WIRELESS COMMUNICATIONS AND INTERNET Future Evolving Technologies The new edition of Advanced Wireless Communications: 4G Cognitive and Cooperative Broadband Technology, 2nd Edition, including the latest developments In the evolution of wireless communications, the dominant challenges are in the areas of networking and their integration with the Future Internet. Even the classical concept of cellular networks is changing and new technologies are evolving to replace it. To reflect these new trends, Advanced Wireless Communications & INTERNET builds upon the previous volumes, enhancing the existing chapters, and including a number of new topics. Systematically guiding readers from the fundamentals through to advanced areas, each chapter begins with an introductory explanation of the basic problems and solutions followed with an analytical treatment in greater detail. The most important aspects of new emerging technologies in wireless communications are comprehensively covered including: next generation Internet; cloud computing and network virtualization; economics of utility computing and wireless grids and clouds. This gives readers an essential understanding of the overall environment in which future wireless networks will be operating. Furthermore, a number of methodologies for maintaining the network connectivity, by using tools ranging from genetic algorithms to stochastic geometry and random graphs theory, and a discussion on percolation and connectivity, are also offered. The book includes a chapter on network formation games, covering the general models, knowledge based network formation games, and coalition games in wireless ad hoc networks. Illustrates points throughout using real-life case studies drawn from the author’s extensive international experience in the field of telecommunications Fully updated to include the latest developments, key topics covered include: advanced routing and network coding; network stability control; relay-assisted Wireless Networks; multicommodity flow optimization problems, flow optimization in heterogeneous networks, and dynamic resource allocation in computing clouds Methodically guides readers through each topic from basic to advanced areas Focuses on system elements that provide adaptability and re-configurability, and discusses how these features can improve wireless communications system performance Enjoyed this book? Why not tell others about it and write a review on your favourite online bookseller.

Download or read book Optimal Detection with Imperfect Channel Estimation for Wireless Communications written by Junruo Zhang and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Iterative Channel Estimation for Wireless Communications written by JoonBeom Kim and published by . This book was released on 2006 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finally, for vertical Bell Laboratories layered space-time OFDM systems, we propose an iterative channel estimator based on a PSAM structure for time-varying multipath fading channels. By exploiting the statistical properties of a wireless channel, we also develop a method to suppress intercarrier interference due to the channel time selectivity, and propose a low-complexity iterative channel estimator that exploits a priori information in an efficient manner.

Download or read book Broadband Wireless Communications written by Jiangzhou Wang and published by Springer Science & Business Media. This book was released on 2006-04-18 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: The broadband wireless communications field is growing at an explosive rate, stimulated by a host of important emerging applications ranging from 3G, 4G and wireless LAN. Wideband CDMA and CDMA2000 will be used for 3G. OFDM+CDMA might be a good choice for 4G, CDMA overlay will possibly be used for new-generation broadband wireless LAN. For system planners and designers, the projections of rapidly escalating demand for such wireless services present major challenges and meeting these challenges will require sustained technical innovation on many fronts. The text of this book has been developed through years of research by the author and his graduate students at the University of Hong Kong. The aim of this book is to provide a R&D perspective on the field of broadband wireless communications by describing the recent research developments in this area and also by identifying key directions in which further research is needed. As a background, I presume that the reader has a thorough understanding of digital communications and spread spectrum/CDMA. The book is arranged into 13 chapters. In chapter 1, some key specifications of 3G WCDMA are described and discussed. These techniques include channel coding, rate matching, modulation and spreading, power control, cell search, transmit diversity, soft-handoff, and so son. In Chapter 2, the coherent RAKE reception of Wideband CDMA signals with complex spreading is considered. A dedicated pilot channel, which is separate from data channels, is used for the purpose of channel estimation.

Download or read book MIMO Wireless Communications written by Ezio Biglieri and published by Cambridge University Press. This book was released on 2007-01-08 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple-input multiple-output (MIMO) technology constitutes a breakthrough in the design of wireless communications systems, and is already at the core of several wireless standards. Exploiting multipath scattering, MIMO techniques deliver significant performance enhancements in terms of data transmission rate and interference reduction. This 2007 book is a detailed introduction to the analysis and design of MIMO wireless systems. Beginning with an overview of MIMO technology, the authors then examine the fundamental capacity limits of MIMO systems. Transmitter design, including precoding and space-time coding, is then treated in depth, and the book closes with two chapters devoted to receiver design. Written by a team of leading experts, the book blends theoretical analysis with physical insights, and highlights a range of key design challenges. It can be used as a textbook for advanced courses on wireless communications, and will also appeal to researchers and practitioners working on MIMO wireless systems.