Distributed Space-time Message Relaying for Uncoded/coded Wireless Cooperative Communications

Distributed Space-time Message Relaying for Uncoded/coded Wireless Cooperative Communications
Author: Peng Huo
Publisher:
Total Pages: 262
Release: 2012
Genre:
ISBN:

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During wireless communications, nodes can overhear other transmissions through the wireless medium, suggested by the broadcast nature of plane wave propagation, and may help to provide extra observations of the source signals to the destination. Modern research in wireless communications pays more attention to these extra observations which were formerly neglected within networks. Cooperative communication processes this abundant information existing at the surrounding nodes and retransmits towards the destination in various forms to create spatial and/or coding diversity, thereby to obtain higher throughput and reliability. The aim of this work is to design cooperative communication systems with distributed space-time block codes (DSTBC) in different relaying protocols and theoretically derive the BER performance for each scenario. The amplify-and-forward (AF) protocol is one of the most commonly used protocols at the relays. It has a low implementation complexity but with a drawback of amplifying the noise as well. We establish the derivation of the exact one-integral expression of the average BER performance of this system, followed by a novel approximation method based on the series expansion. An emerging technology, soft decode-and-forward (SDF), has been presented to combine the desired features of AF and DF: soft signal representation in AF and channel coding gain in DF. In the SDF protocol, after decoding, relays transmit the soft-information, which represents the reliability of symbols passed by the decoder, to the destination. Instead of keeping the source node idling when the relays transmit as in the traditional SDF system, we let the source transmit hard information and cooperate with the relays using DSTBC. By theoretically deriving the detection performance at the destination by either using or not using the DSTBC, we make comparisons among three SDF systems. Interesting results have been shown, together with Monte-Carlo simulations, to illustrate that our proposed one-relay and two-relay SDF & DSTBC systems outperform traditional soft relaying for most of the cases. Finally, these analytic results also provide a way to implement the optimal power allocation between the source and the relay or between relays, which is illustrated in the line model.

Distributed Space-Time Coding

Distributed Space-Time Coding
Author: Yindi Jing
Publisher: Springer Science & Business Media
Total Pages: 118
Release: 2013-04-23
Genre: Technology & Engineering
ISBN: 1461468310

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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.

Distributed Space-time Block Coding in Cooperative Relay Networks with Application in Cognitive Radio

Distributed Space-time Block Coding in Cooperative Relay Networks with Application in Cognitive Radio
Author: Faisal T. Alotaibi
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:

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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.

Distributed Space Time Block Code in Asynchronous Cooperative Networks

Distributed Space Time Block Code in Asynchronous Cooperative Networks
Author: Mohammed Taha El Astal
Publisher: LAP Lambert Academic Publishing
Total Pages: 100
Release: 2011-05
Genre:
ISBN: 9783844392685

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Space- Time Block Coding (STBC) are used to improve the transmission reliably and spectral efficiency of MIMO systems. The cooperative communication techniques can avoid the difficulties of implementing actual antennas array by converting the single-input single-output (SISO) system into a virtual multiple-input multiple-output (MIMO) system. When STBC applied to cooperative diversity the system termed as Distributed Space Time Block Code (D-STBC). Most of the existing research assumes perfect synchronization among cooperative users in D-STBC. Unfortunately, perfect synchronization is almost impossible to be achieved. Therefore, most of the designed space-time codes are no longer valid. There are different research efforts to overcome this problem; most of which has high decoding complexity. In this research, two low decoding complexity schemes for imperfect synchronized D-STBC have been proposed. The first scheme is based on the principle of parallel interference cancellation (PIC), whereas the other is based on successive interference cancellation (SIC). These approaches have been proved to be a very effective in suppressing the impact of imperfect synchronization.

Cooperative Communications

Cooperative Communications
Author: Mischa Dohler
Publisher: John Wiley & Sons
Total Pages: 464
Release: 2010-01-29
Genre: Technology & Engineering
ISBN: 9780470740064

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Facilitating Cooperation for Wireless Systems Cooperative Communications: Hardware, Channel & PHY focuses on issues pertaining to the PHY layer of wireless communication networks, offering a rigorous taxonomy of this dispersed field, along with a range of application scenarios for cooperative and distributed schemes, demonstrating how these techniques can be employed. The authors discuss hardware, complexity and power consumption issues, which are vital for understanding what can be realized at the PHY layer, showing how wireless channel models differ from more traditional models, and highlighting the reliance of PHY algorithm performance on the underlying channel models. Numerous transparent and regenerative relaying protocols are described in detail for a variety of transparent and regenerative cooperative schemes. Key Features: Introduces background, concepts, applications, milestones and thorough taxonomy Identifies the potential in this emerging technology applied to e.g. LTE/WiMAX, WSN Discusses latest wireless channel models for transparent and regenerative protocols Addresses the fundamentals as well as latest emerging PHY protocols Introduces transparent distributed STBC, STTC, multiplexing and beamforming protocols Quantifies regenerative distributed space-time, channel and network coding protocols Explores system optimization, such as distributed power allocation and relay selection Introduces and compares analog and digital hardware architectures Quantifies complexity, memory and power consumption of 3G UMTS & 4G LTE/WiMAX relay Highlights future research challenges within the cooperative communications field This book is an invaluable guide for professionals and researchers in communications fields. It will also be of interest to graduates of communications and electronic engineering courses. It forms part of an entire series dedicated to cooperative wireless systems.

Distributed Space-Time Block Codes in Wireless Cooperative Networks

Distributed Space-Time Block Codes in Wireless Cooperative Networks
Author:
Publisher:
Total Pages:
Release: 2006
Genre:
ISBN:

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In cooperative networks, relays cooperate and form a distributed multi-antenna system to provide spatial diversity. In order to achieve high bandwidth efficiency, distributed space-time block codes (DSTBCs) are proposed and have been studied extensively. Among all DSTBCs, this thesis focuses on the codes which are single-symbol maximum likelihood (ML) decodable and can achieve the full diversity order. This thesis presents four works on single-symbol ML decodable DSTBCs. The first work proposes the row-monomial distributed orthogonal space-time block codes (DOSTBCs). We find an upper bound of the data-rate of the row-monomial DOSTBC and construct the codes achieving this upper bound. In the second work, we first study the general DOSTBCs and derive an upper bound of the data-rate of the DOSTBC. Secondly, we propose the row-monomial DOSTBCs with channel phase information (DOSTBCs-CPI) and derive an upper bound of the data-rate of those codes. Furthermore, we find the actual row-monomial DOSTBCs-CPI which achieve the upper bound of the data-rate. In the third and fourth works of this thesis, we focus on error performance analysis of single-symbol ML decodable DSTBCs. Specifically, we study the distributed Alamouti's code in dissimilar cooperative networks. In the third work, we assume that the relays are blind relays and we derive two very accurate approximate bit error rate (BER) expressions of the distributed Alamouti's code. In the fourth work, we assume that the relays are CSI-assisted relays. When those CSI-assisted relays adopt the amplifying coefficients that was proposed in [33] and widely used in many previous publications, upper and lower bounds of the BER of the distributed Alamouti's code are derived. Very surprisingly, the lower bound indicates that the code cannot achieve the full diversity order when the CSI-assisted relays adopt the amplifying coefficients proposed in [33]. Therefore, we propose a new threshold-based amplifying coefficient and it makes.

Space-time Code Design for Wireless Communication Systems

Space-time Code Design for Wireless Communication Systems
Author: Xiaoyong Guo
Publisher:
Total Pages:
Release: 2010
Genre: Antennas (Electronics)
ISBN: 9781109671575

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It is well understood that MIMO technology could enhance the reliability of wireless communication and increase the channel capacity. The design of space-time code to explore the benefit provided by the multi-antenna systems is of key importance. This dissertation addresses several issues concerning the design of space-time code. The following is a brief description of these issues and our contributions. Cyclic division algebra (CDA) has been introduced as a means to construct full-rate nonvanishing determinant STBC (space-time block code), which achieves the diversity-multiplexing trade-off and has a very good performance. There are two steps to construct CDA-based nonvanishing determinant STBC: construction of a cyclic extension over [Special characters omitted.] (i) and finding a non-norm element. For the first step we proposed a new up-to-down construction method. With this new method we find a broad range of cyclic extensions over [Special characters omitted.] (i), which encompasses all the previous constructions. For the second step, we give new criteria for the non-norm element. Non-norm elements found by these new criteria have smaller absolute values, hence the resulted STBC has a better coding gain. The well-known design criteria for space-time code is proposed by Guey-Fitz-Bell-Kuo in 1996 and Tarokh-Seshadri-Calderbank in 1998. The derivation of the design criteria is based on the assumption that the received signals are decoded with an ML receiver. One important issue seems to be long ignored: there is no design criterion for space-time code decoded with suboptimal receivers. Only until recently that Zhang-Liu-Wong and Shang-Xia studied the full diversity codes with linear receivers. We address the issue in a much broader sense. We proposed a more general receiver structure called PIC (partial interference cancellation) group decoding. A PIC group decoding can be viewed as an intermediate decoding algorithm between linear decoding and ML decoding. It encompasses both linear decoding and ML decoding as its two extremes. We also derived a design criterion for space-time codes with PIC receivers to achieve full diversity. The full diversity criteria for codes with ML receivers and linear receivers are special cases of our new design criterion. In many applications, wireless communication devices are limited by size or hardware complexity to one antenna. Cooperative communication was introduced for communication networks with single-antenna nodes to exploit the multi-path diversity. In cooperative communications, a few nodes positioned between the source node and destination node are served as the relay nodes. One important problem for cooperative communication networks is the time-asynchronism among the relay nodes. We propose a distributed space-time coding scheme called distributed linear convolutional space-time code (DLC-STC) to address this problem. We also give systematic construction methods of DLC-STC which achieves full diversity without time synchronization among the relay nodes. Furthermore, we show that our proposed DLC-STC achieves full diversity even with suboptimal receivers such as ZF/MMSE receiver and DFE receiver.

Space-Time Coding

Space-Time Coding
Author: Hamid Jafarkhani
Publisher: Cambridge University Press
Total Pages: 320
Release: 2005-09-22
Genre: Technology & Engineering
ISBN: 1139444441

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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.

Design and Performance Analysis of Distributed Space Time Coding Schemes for Cooperative Wireless Networks

Design and Performance Analysis of Distributed Space Time Coding Schemes for Cooperative Wireless Networks
Author: Gbenga Adetokunbo Owojaiye
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:

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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.