Download or read book Space time Coding and Orthogonal Frequency Division Multiplexing in Cooperative Wireless Relays written by Yan Mei and published by . This book was released on 2006 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Distributed Space time Block Coding in Cooperative Relay Networks with Application in Cognitive Radio written by Faisal T. Alotaibi and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spatial diversity is an effective technique to combat the effects of severe fading in wireless environments. Recently, cooperative communications has emerged as an attractive communications paradigm that can introduce a new form of spatial diversity which is known as cooperative diversity, that can enhance system reliability without sacrificing the scarce bandwidth resource or consuming more transmit power. It enables single-antenna terminals in a wireless relay network to share their antennas to form a virtual antenna array on the basis of their distributed locations. As such, the same diversity gains as in multi-input multi-output systems can be achieved without requiring multiple-antenna terminals. In this thesis, a new approach to cooperative communications via distributed extended orthogonal space-time block coding (D-EO-STBC) based on limited partial feedback is proposed for cooperative relay networks with three and four relay nodes and then generalized for an arbitrary number of relay nodes. This scheme can achieve full cooperative diversity and full transmission rate in addition to array gain, and it has certain properties that make it alluring for practical systems such as orthogonality, flexibility, low computational complexity and decoding delay, and high robustness to node failure. Versions of the closed-loop D-EO-STBC scheme based on cooperative orthogonal frequency division multiplexing type transmission are also proposed for both flat and frequency-selective fading channels which can overcome imperfect synchronization in the network. As such, this proposed technique can effectively cope with the effects of fading and timing errors. Moreover, to increase the end-to-end data rate, this scheme is extended for two-way relay networks through a three-time slot framework. On the other hand, to substantially reduce the feedback channel overhead, limited feedback approaches based on parameter quantization are proposed. In particular, an optimal one-bit partial feedback approach is proposed for the generalized D-O-STBC scheme to maximize the array gain. To further enhance the end-to-end bit error rate performance of the cooperative relay system, a relay selection scheme based on D-EO-STBC is then proposed. Finally, to highlight the utility of the proposed D-EO-STBC scheme, an application to cognitive radio is studied.

Download or read book Orthogonal Frequency Division Multiplexing for Wireless Communications written by Ye Geoffrey Li and published by Springer Science & Business Media. This book was released on 2006-05-31 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal Frequency Division Multiplexing for Wireless Communications is an edited volume with contributions by leading authorities in the subject of OFDM. Its coverage consists of principles, important wireless topics (e.g. Synchronization, channel estimation, etc.) and techniques. Included is information for advancing wireless communication in a multipath environment with an emphasis on implementation of OFDM in base stations. Orthogonal Frequency Division Multiplexing for Wireless Communications provides a comprehensive introduction of the theory and practice of OFDM. To facilitate the readers, extensive subject indices and references are given at the end of the book. Even though each chapter is written by different experts, symbols and notations in all chapters of the book are consistent.

Download or read book Distributed Space Time Block Coding in Asynchronous Cooperative Relay Networks written by A. M. Elazreg and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The design and analysis of various distributed space time block coding schemes for asynchronous cooperative relay networks is considered in this thesis. Rayleigh frequency flat fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing type transmission approach are employed to mitigate the synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied, and a new Alamouti space time block coding technique with parallel interference cancellation detection which does not require such a direct link connection and employs two relay nodes is proposed. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. Novel detection schemes are then proposed for decode-and-forward networks with closed-loop extended orthogonal coding which reduce the computational complexity of the parallel interference cancellation. Both sub-optimum and near-optimum detectors are presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approaches and their ability to mitigate synchronization errors. A relay selection approach is also formulated which maximizes spatial diversity gain and attains robustness to timing errors. Finally, a new closed-loop distributed extended orthogonal space time block coding solution for amplify-and-forward type networks which minimizes the number of feedback bits by using a cyclic rotation phase is presented. This approach utilizes an orthogonal frequency division multiplexing type transmission structure with a cyclic prefix to mitigate synchronization errors. End-to-end bit error performance evaluations verify the efficacy of the scheme and its success in overcoming synchronization errors.

Download or read book Space time frequency Coded Mimo and Cooperative OFDM Systems written by Zhefeng Li and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Space-time-frequency coded Multiple-Input and Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems have recently attracted much attention for broadband wireless communications including recent IEEE standards 802.11n and 802.16e. Space-time/Frequency Coding (SFC) can achieve the spatial and multipath diversities for a MIMO-OFDM system by coding across multiple antennas and subcarriers. In this research, we focus on a family of space-time-frequency codes proposed by Zhang et al to achieve both full spatial and multipath diversities by using Orthogonal Space-Time Block Codes (OSTBC). In particular, we develop a precoding algorithm for Peak-to-Average Power Ratio (PAPR) reduction and a clipping noise model based Maximum Likelihood (ML) decoding algorithm for Space-Time-Frequency Block Codes (STFBC) coded MIMO-OFDM systems. An important issue for OFDM systems is their high PAPR and it is important to reduce the PAPR in a practical (power efficient) system. The first goal of this research is to modify the repeating process and adjust phases of coded symbols so that the PAPR of the OFDM system is reduced. In particular, we propose to use Chu sequences for phase adjustment and show that the discrete PAPR can be reduced by & Gamma; times where & Gamma; is the times of the repeating across subcarriers. Another efficient way to reduce the PAPR in OFDM systems is clipping. After the clipping in an MIMO-OFDM system, the overall additive noise, including the clipping distortion, may not be white. The second goal of this research is to develop fast ML decoding algorithms for Orthogonal Space-Time-Frequency Block Codes (OSTFBC) and Quasi Orthogonal Space-Time-Frequency Block Codes (QOSTFBC) in clipped MIMO-OFDM systems. By using a clipping noise model with Gaussian approximation, our newly proposed fast ML decoding algorithms improve the system performance without increasing the decoding complexity. Simulation results are presented to illustrate the improvement. In order to apply the clipping noise model based ML decoding, the clipping ratio needs to be known at the receiver. We also consider the case when the clipping ratio is not known at the receiver. So a decision-aided clipping ratio estimation for MIMO-OFDM systems is proposed in our research, too. Except for MIMO-OFDM systems, in this work, cooperative OFDM system is investigated too. OFDM transmission has been proposed for cooperative communications to combat the time delays from the relay nodes, where the paths from relay nodes to destination node are treated as multipaths and space-time (or frequency) coding is used to achieve the spatial (or multipath) diversity. With this approach, when the Cyclic Prefix (CP) length is less than the time delay length, inter-block interference occurs. In this research, we consider Alamouti coded OFDM systems in cooperative communications where the CP length may be less than the time delay length. By taking the advantage of the Alamouti code structure, we propose a time domain interference cancellation algorithm.

Download or read book Orthogonal Frequency Division Multiplexing with Diversity for Future Wireless Systems written by Khoa N. Le and published by Bentham Science Publishers. This book was released on 2012 with total page 621 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The book examines several aspects of Orthogonal Frequency Division Multiplexing (OFDM) employing linear diversity techniques such as inter-carrier interference, bit error rate, peak to average power and inter-block interference. It should be a useful refe"

Download or read book Cooperation in Wireless Networks Principles and Applications written by Frank H. P. Fitzek and published by Springer Science & Business Media. This book was released on 2006-07-25 with total page 679 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cooperation in Wireless Networks: Principles and Applications covers the underlying principles of cooperative techniques as well as several applications demonstrating the use of such techniques in practical systems. The book is written in a collaborative manner by several authors from Asia, America, and Europe. This book puts into one volume a comprehensive and technically rich appraisal of the wireless communications scene from a cooperation point of view.

Download or read book Cooperative Communications for Improved Wireless Network Transmission Framework for Virtual Antenna Array Applications written by Uysal, Murat and published by IGI Global. This book was released on 2009-07-31 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offers practitioners, researchers, and academicians with fundamental principles of cooperative communication. This book provides readers diverse findings and exposes underlying issues in the analysis, design, and optimization of wireless systems.

Download or read book Space Time Coding written by Hamid Jafarkhani and published by Cambridge University Press. This book was released on 2005-09-22 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the fundamental principles of space-time coding for wireless communications over multiple-input multiple-output (MIMO) channels, and sets out practical coding methods for achieving the performance improvements predicted by the theory. Starting with background material on wireless communications and the capacity of MIMO channels, the book then reviews design criteria for space-time codes. A detailed treatment of the theory behind space-time block codes then leads on to an in-depth discussion of space-time trellis codes. The book continues with discussion of differential space-time modulation, BLAST and some other space-time processing methods and the final chapter addresses additional topics in space-time coding. The theory and practice sections can be used independently of each other. Written by one of the inventors of space-time block coding, this book is ideal for a graduate student familiar with the basics of digital communications, and for engineers implementing the theory in real systems.

Download or read book Coherent Cooperative Relaying in Low Mobility Wireless Multiuser Networks written by Stefan Berger and published by Logos Verlag Berlin GmbH. This book was released on 2010 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, several important aspects of cooperative wireless multiuser networks are investigated. The focus lies on coherent two-hop relaying networks where several amplify-and-forward (AF) relays assist the communication between multiple source-destination pairs. First, the impact of local oscillator (LO) imperfections and I/Q imbalance at the relays on two-hop relaying is investigated. A special focus lies on the comparison between frequency division duplexing (FDD) and time division duplexing (TDD) relays. Based on the observation that the direction in which a channel between two wireless nodes is measured has an impact on the estimate, phase synchronization requirements for coherent relaying networks are then found. Several channel estimation protocols that differ in the direction in which the single-hop channels are measured are furthermore identi'ed and their performance is compared. Next, a very simple phase synchronization scheme is presented that provides a set of relays with a common LO phase. Two coherent beamforming schemes, namely multiuser zero-forcing (MUZF) and multiuser minimum mean squared error (MMSE) relaying, are then investigated. Finally, a real-world demonstrator for distributed wireless communication networks (called RACooN Lab) is presented. It was used to implement coherent cooperative communication schemes on a practical two-hop relaying network.

Download or read book Distributed Space Time Coding written by Yindi Jing and published by Springer Science & Business Media. This book was released on 2013-04-23 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Distributed Space-Time Coding (DSTC) is a cooperative relaying scheme that enables high reliability in wireless networks. This brief presents the basic concept of DSTC, its achievable performance, generalizations, code design, and differential use. Recent results on training design and channel estimation for DSTC and the performance of training-based DSTC are also discussed.

Download or read book Ofdm Based Relay Systems for Future Wireless Communications written by Milica Pejanovic-Djurisic and published by CRC Press. This book was released on 2022-09-01 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Relay systems have become a subject of intensive research interest over the recent years, as it is recognized that they can improve performances and extend the coverage area of wireless communication systems. Special attention has been dedicated to them since the proposal appeared for their implementation in mobile cellular systems. Numerous researches conducted after that proposal have enabled incorporation of OFDM based relay systems in both accepted standards for IMT-Advanced systems. Nowadays, researches are ongoing with the aim to define new solutions for performance improvement of the standardized OFDM relay systems for cellular networks and one of the interesting solutions is implementation of subcarrier permutation (SCP) at the relay (R) station.The book OFDM based relay systems for future wireless communications presents a comprehensive research results in analyzing behavior and performance of the OFDM based relay systems with SCP. Dual-hop relay scenario with three communication terminals, and no direct link between the source (S) and the destination (D) has been analyzed, as it is compliant with the accepted solutions for IMT-Advanced systems. The book includes performance analysis and performance comparison of OFDM based:• amplify-and-forward (AF) relay systems with fixed gain (FG),• amplify-and-forward (AF) relay systems with variable gain (VG),• decode-and-forward (DF) relay systems,each including two SCP schemes, known to maximize the system capacity and/or improve the bit error rate (BER) performances. Performance comparisons have enabled definition of optimal solutions for the future wireless communication systems in a given conditions, and for the given optimality criteria. OFDM based relay systems for future wireless communications contains recent research results in this area and is ideal for the academic staff and master/research students in area of mobile communication systems, as well as for the personnel in communication industry.

Download or read book Ultra Wideband Communications Systems written by W. Pam Siriwongpairat and published by John Wiley & Sons. This book was released on 2007-11-16 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The only book that provides full coverage of UWB multiband OFDM technology Ultra-wideband (UWB) has emerged as a technology that offers great promise to satisfy the growing demand for low-cost, high-speed digital networks. The enormous bandwidth available, the potential for high data rates, and the promise for small size and low processing power with reduced implementation cost all present a unique opportunity for UWB to become a widely adopted radio solution for future wireless home networking technology. Ultra-Wideband Communications Systems is the first book to provide comprehensive coverage of the fundamental and advanced issues related to UWB technology, with a particular focus on multiband orthogonal frequency division multiplexing (multiband OFDM). The multiband OFDM approach was a leading method in the IEEE 802.15.3astandard and has recently been standardized by ECMA International. The book also explores several major advanced state-of-the-art technologies to enhance the performance of the standardized multiband OFDM approach. Additional coverage includes: * Characteristics of UWB channels * An overview of UWB single-band and multiband OFDM approaches * MIMO multiband OFDM * Performance characterization * Performance under practical considerations * Differential multiband OFDM * Power-controlled channel allocation * Cooperative UWB multiband OFDM Complete with pointers for future research opportunities to enhance the performance of UWB multiband OFDM technology over current and future wireless networks, this is an indispensable resource for graduate students, engineers, and academic and industrial researchers involved with UWB.

Download or read book MIMO OFDM for LTE WiFi and WiMAX written by Lajos Hanzo and published by John Wiley & Sons. This book was released on 2012-01-03 with total page 693 pages. Available in PDF, EPUB and Kindle. Book excerpt: MIMO-OFDM for LTE, WIFI and WIMAX: Coherent versus Non-Coherent and Cooperative Turbo-Transceivers provides an up-to-date portrayal of wireless transmission based on OFDM techniques augmented with Space-Time Block Codes (STBCs) and Spatial-Division Multiple Access (SDMA). The volume also offers an in-depth treatment of cutting-edge Cooperative Communications. This monograph collates the latest techniques in a number of specific design areas of turbo-detected MIMO-OFDM wireless systems. As a result a wide range of topical subjects are examined, including channel coding and multiuser detection (MUD), with a special emphasis on optimum maximum-likelihood (ML) MUDs, reduced-complexity genetic algorithm aided near-ML MUDs and sphere detection. The benefits of spreading codes as well as joint iterative channel and data estimation are only a few of the radical new features of the book. Also considered are the benefits of turbo and LDPC channel coding, the entire suite of known joint coding and modulation schemes, space-time coding as well as SDM/SDMA MIMOs within the context of various application examples. The book systematically converts the lessons of Shannon's information theory into design principles applicable to practical wireless systems; the depth of discussions increases towards the end of the book. Discusses many state-of-the-art topics important to today's wireless communications engineers. Includes numerous complete system design examples for the industrial practitioner. Offers a detailed portrayal of sphere detection. Based on over twenty years of research into OFDM in the context of various applications, subsequently presenting comprehensive bibliographies.

Download or read book Space Time Coding for Broadband Wireless Communications written by Georgios B. Giannakis and published by John Wiley & Sons. This book was released on 2007-02-26 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Eine vielversprechende Technologie zur Maximierung der Bandbreiteneffizienz in der breitbandigen drahtlosen Kommunikation ist die Raum-Zeit-Kodierung. Theorie und Praxis verbindend, ist dieses Buch die erste umfassende Diskussion von Grundlagen und designorientierten Aspekten von Raum-Zeit-Codes. Single-Carrier und Multi-Carrier-Übertragungen für Einzel- und Mehrnutzerkommunikation werden behandelt.

Download or read book Relay Diversity Techniques of Orthogonal Frequency division Multiplexing and Multi carrier Code Division Multiple Access written by Nur I. Abdul Razak and published by . This book was released on 2012 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: The future of mobile and personal communications requires a system that can support a large number of users and has the ability to provide high-speed services. Meeting this demand is challenging since wireless communications are subject to these four major constraints: complex fading channels, a scarce usable radio spectrum, and limitations on the power and size of the mobile terminals. Space-time codes, such as the Alamouti/space-time block coding (STBC) and cyclic delay diversity (CDD) can provide diversity and coding gains in multiple-input multiple-output (MIMO) systems over fading channels. However in an ad-hoc network, nodes are often constrained in hard-ware complexity and size, which makes MIMO systems impractical for certain applications. Cooperative relay diversity schemes have been introduced in an effort to overcome these limitations. Cooperative techniques allow a collection of communication nodes to cooperate with to relay signals amongst each other, effectively creating a virtual antenna array, which combat multipath fading in wireless channels. This thesis investigates relay diversity techniques in cooperative com-munications, namely the distributed space-time block coding (DSTBC) and relay cyclic delay diversity (RCDD) for OFDM and MC-CDMA systems. The performance analysis of the wireless relay networks un¬der different protocols and fading channels are investigated. We de¬rived the formulas for the symbol error rate (SER) of the investigated schemes in fading channels. Finally, a novel hybrid relay diversity (HRD) is presented for OFDM-based system. This new relay structure addresses the issue of achiev¬ing a full spatial and multipath diversity by developing a hybrid for CDD and STBC. Simulation on the system performance of HRD shows the superiority of the technique compared to standalone DSTBC and RCDD.

Download or read book Design and Performance Analysis of Distributed Space Time Coding Schemes for Cooperative Wireless Networks written by Gbenga Adetokunbo Owojaiye and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, space-time block codes originally developed for multiple antenna systems are extended to cooperative multi-hop networks. The designs are applicable to any wireless network setting especially cellular, adhoc and sensor networks where space limitations preclude the use of multiple antennas. The thesis first investigates the design of distributed orthogonal and quasi-orthogonal space time block codes in cooperative networks with single and multiple antennas at the destination. Numerical and simulation results show that by employing multiple receive antennas the diversity performance of the network is further improved at the expense of slight modification of the detection scheme. The thesis then focuses on designing distributed space time block codes for cooperative networks in which the source node participates in cooperation. Based on this, a source-assisting strategy is proposed for distributed orthogonal and quasi-orthogonal space time block codes. Numerical and simulation results show that the source-assisting strategy exhibits improved diversity performance compared to the conventional distributed orthogonal and quasi-orthogonal designs. Motivated by the problem of channel state information acquisition in practical wireless network environments, the design of differential distributed space time block codes is investigated. Specifically, a co-efficient vector-based differential encoding and decoding scheme is proposed for cooperative networks. The thesis then explores the concatenation of differential strategies with several distributed space time block coding schemes namely; the Alamouti code, square-real orthogonal codes, complex-orthogonal codes, and quasiorthogonal codes, using cooperative networks with different number of relay nodes. In order to cater for high data rate transmission in non-coherent cooperative networks, differential distributed quasi-orthogonal space-time block codes which are capable of achieving full code-rate and full diversity are proposed. Simulation results demonstrate that the differential distributed quasi-orthogonal space-time block codes outperform existing distributed space time block coding schemes in terms of code rate and bit-error-rate performance. A multidifferential distributed quasi-orthogonal space-time block coding scheme is also proposed to exploit the additional diversity path provided by the source-destination link. A major challenge is how to construct full rate codes for non-coherent cooperative broadband networks with more than two relay nodes while exploiting the achievable spatial and frequency diversity. In this thesis, full rate quasi-orthogonal codes are designed for noncoherent cooperative broadband networks where channel state information is unavailable. From this, a generalized differential distributed quasi-orthogonal space-frequency coding scheme is proposed for cooperative broadband networks. The proposed scheme is able to achieve full rate and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of the proposed scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, sufficient conditions are derived for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity. In order to exploit the additional diversity paths provided by the source-destination link, a novel multidifferential distributed quasi-orthogonal space-frequency coding scheme is proposed. The overall objective of the new scheme is to improve the quality of the detected signal at the destination with negligible increase in the computational complexity of the detector. Finally, a differential distributed quasi-orthogonal space-time-frequency coding scheme is proposed to cater for high data rate transmission and improve the performance of noncoherent cooperative broadband networks operating in highly mobile environments. The approach is to integrate the concept of distributed space-time-frequency coding with differential modulation, and employ rotated constellation quasi-orthogonal codes. From this, we design a scheme which is able to address the problem of performance degradation in highly selective fading environments while guaranteeing non-coherent signal recovery and full code rate in cooperative broadband networks. The coding scheme employed in this thesis relaxes the assumption of constant channel variation in the temporal and frequency dimensions over long symbol periods, thus performance degradation is reduced in frequencyselective and time-selective fading environments. Simulation results illustrate the performance of the proposed differential distributed quasi-orthogonal space-time-frequency coding scheme under different channel conditions.