Download or read book Channel Estimation for Amplify and forward Channels written by Gedik Berna and published by . This book was released on 2008 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cooperative diversity has been proposed as a powerful means to enhance the performance of high-rate communications over wireless fading channels. It realizes spatial diversity advantages in a distributed manner where two or more nodes share their antennas to mimic a virtual antenna array.

Download or read book Channel Estimation for Amplify and Forward Relay Networks written by Panagiota Lioliou and published by . This book was released on 2009 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spectrally efficient Approaches to Channel Estimation for Amplify and forward Two way Relay Networks written by Saeed Abdallah and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To demonstrate the achievability of these gains, we derive an expectation maximization (EM)-based semi-blind algorithm that performs very closely to the derived CRB. In the last part of the thesis, we consider semi-blind channel estimation for OFDM-based TWRNs operating in frequency selective channel conditions. To assist in the estimation of the individual channels, superimposed training is adopted at the relay. Our proposed semi-blind estimation algorithm is based on the Gaussian ML approach. We design the pilot vectors of the terminals and relay to optimize estimation performance. Our simulations show that the proposed method provides significant improvements in estimation accuracy. " --

Download or read book Channel Estimation for OFDM in Amplify and Forward Relay Systems written by 陳重亨 and published by . This book was released on 2009 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cram r Rao Bounds of Unbiased Channel Estimation for Amplify and forward Relay Networks written by 黎博幼 and published by . This book was released on 2010 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Channel Estimation for Physical Layer Network Coding Systems written by Feifei Gao and published by Springer. This book was released on 2014-10-15 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: This SpringerBrief presents channel estimation strategies for the physical later network coding (PLNC) systems. Along with a review of PLNC architectures, this brief examines new challenges brought by the special structure of bi-directional two-hop transmissions that are different from the traditional point-to-point systems and unidirectional relay systems. The authors discuss the channel estimation strategies over typical fading scenarios, including frequency flat fading, frequency selective fading and time selective fading, as well as future research directions. Chapters explore the performance of the channel estimation strategy and optimal structure of training sequences for each scenario. Besides the analysis of channel estimation strategies, the book also points out the necessity of revisiting other signal processing issues for the PLNC system. Channel Estimation of Physical Layer Network Coding Systems is a valuable resource for researchers and professionals working in wireless communications and networks. Advanced-level students studying computer science and electrical engineering will also find the content helpful.

Download or read book Channel Estimation and Optimal Resource Allocation of Relay Assisted Communication Systems written by Yupeng Jia and published by . This book was released on 2012 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Exploding demand for various wireless services has fueled significant development of wireless communication systems and networks in the past few decades. Wireless service providers are continuously striving to improve the design of communication systems and to enable higher data rate and more reliable wireless transmission. A major challenge in designing these systems is the random nature of the wireless transmission media due to the fading process. A recent paradigm shift from the conventional point-to-point communications is relay assisted communications. Motivated by the great success of multiple-input multiple-output (MIMO) wireless communication systems, with multiple transmit and receive antennas, researchers have considered relay assisted communications. Relying on the broadcast nature of the wireless media, a relay assisted communication system emulates a virtual MIMO system and exploits the spatial diversity, also known as cooperative diversity. Cooperative diversity increases the transmission reliability and coverage, without expanding the expenditure of the scarce transmission resources (power and bandwidth). Recently, the research community has witnessed an increasing interest in studying relay assisted communication systems. These studies include proposing novel relaying schemes, exploring ways to maximize the cooperative gain, and investigating the fundamental performance limits of these systems. The bulk of the literature is based on the main assumption that the effect of fading channels (commonly referred to as channel state information) is perfectly known at the destination. In practical communication systems, however, the unknown fading channels are first estimated and the channel estimates are used for decoding the message transmitted by the source. In order to have a more realistic and accurate understanding of the benefits of relay assisted systems, one needs to study the effect of uncertainty, imposed by channel estimation error, on the fundamental performance limits. Such study can guide to a more efficient system design and provide optimal resource allocation between data and training (required for channel estimation). Two widely used relay assisted wireless communication systems are: 1) a one-way relay assisted system, in which there is a source, a relay and a destination, and the relay helps the source by forwarding the overheard message to the destination; 2) a two-way relay assisted system, in which two sources are interested in mutual communication, i.e., one source is the destination of the other source. In this system the relay helps both users by forwarding the overheard messages to the intended destinations. For each system, one can envision different system designs, depending on the specific relaying scheme and the specific signal processing algorithm adopted at the relay. The most commonly used relaying schemes are Amplify-and-Forward (AF) and Decodeand- Forward (DF), where in the former the relay amplifies and forwards the overheard messages, while in the latter, the relay decodes the overheard messages and then forwards them. In this thesis, we consider one-way and two-way AF relay assisted systems with a half-duplex relay. We study the impact of uncertainty, due to channel estimation errors, on the fundamental performance limits. In particular, we consider mean squared error (MSE) and the Bayesian Cramer -Rao lower bound (CRLB) for channel estimation as the estimation theoretic optimality criteria and channel mutual information lower bound and outage probability upper bound as the information theoretic optimality criteria. We explore how the negative effect of channel uncertainty can be mitigated, via optimal transmission resource allocation that maximizes or minimizes a specific optimality criteria. We also compare the bidirectional mutual information lower bounds of direct transmission without the relay, one-way AF relay and two-way AF relay systems. Furthermore, we examine the effect of joint optimization of the media access control and physical layers on the system throughput for one-way AF and DF relay assisted systems"--Abstract.

Download or read book Cooperative Communications written by Mischa Dohler and published by John Wiley & Sons. This book was released on 2010-01-29 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Machine Learning and Intelligent Communications written by Mingxiang Guan and published by Springer Nature. This book was released on 2021-01-23 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume constitutes the refereed post-conference proceedings of the 5th International Conference on Machine Learning and Intelligent Communications, MLICOM 2020, held in Shenzhen, China, in September 2020. Due to COVID-19 pandemic the conference was held virtually. The 55 revised full papers were carefully selected from 133 submissions. The papers are organized thematically in intelligent resource ( spectrum, power) allocation schemes; applications of neural network and deep learning; decentralized learning for wireless communication systems; intelligent antennas design and dynamic configuration; intelligent communications; intelligent positioning and navigation systems; smart unmanned vehicular technology; intelligent space and terrestrial integrated networks; machine learning algorithm and Intelligent networks.

Download or read book Issues in Electronics Research and Application 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 3091 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Electronics Research and Application: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Electronics Research and Application. The editors have built Issues in Electronics Research and Application: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Electronics Research and Application in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Electronics Research and Application: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

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 Low Complexity Approaches to Forward Link Channel Estimation written by Betty Ah Tong Lam and published by . This book was released on 2006 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Issues in Electronics Research and Application 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-05-01 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Electronics Research and Application: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Radar and Sonar Research. The editors have built Issues in Electronics Research and Application: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Radar and Sonar Research in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Electronics Research and Application: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Communications Over Fading Channels with Partial Channel Information written by Xinmin Deng and published by . This book was released on 2005 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of system parameters upon the performance are quantified under the assumption that some statistical information of the wireless fading channels is available. These results are useful in determining the optimal design of system parameters. Suboptimal receivers are designed for systems that are constrained in terms of implementation complexity. The achievable rates are investigated for a wireless communication system when neither the transmitter nor the receiver has prior knowledge of the channel state information (CSI). Quantitative results are provided for independent and identically distributed (i.i.d.) Gaussian signals. A simple, low-duty-cycle signaling scheme is proposed to improve the information rates for low signal-to-noise ratio (SNR), and the optimal duty cycle is expressed as a function of the fading rate and SNR. It is demonstrated that the resource allocations and duty cycles developed for Gaussian signals can also be applied to systems using other signaling formats. The average SNR and outage probabilities are examined for amplify-and-forward cooperative relaying schemes in Rayleigh fading channels. Simple power allocation strategies are determined by using knowledge of the mean strengths of the channels. Suboptimal algorithms are proposed for cases that optimal receivers are difficult to implement. For systems with multiple transmit antennas, an iterative method is used to avoid the inversion of a data-dependent matrix in decision-directed channel estimation. When CSI is not available, two noncoherent detection algorithms are formulated based on the generalized likelihood ratio test (GLRT). Numerical results are presented to demonstrate the use of GLRT-based detectors in systems with cooperative diversity.

Download or read book Massive MIMO written by Hien Quoc Ngo and published by Linköping University Electronic Press. This book was released on 2015-01-16 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last ten years have seen a massive growth in the number of connected wireless devices. Billions of devices are connected and managed by wireless networks. At the same time, each device needs a high throughput to support applications such as voice, real-time video, movies, and games. Demands for wireless throughput and the number of wireless devices will always increase. In addition, there is a growing concern about energy consumption of wireless communication systems. Thus, future wireless systems have to satisfy three main requirements: i) having a high throughput; ii) simultaneously serving many users; and iii) having less energy consumption. Massive multiple-input multiple-output (MIMO) technology, where a base station (BS) equipped with very large number of antennas (collocated or distributed) serves many users in the same time-frequency resource, can meet the above requirements, and hence, it is a promising candidate technology for next generations of wireless systems. With massive antenna arrays at the BS, for most propagation environments, the channels become favorable, i.e., the channel vectors between the users and the BS are (nearly) pairwisely orthogonal, and hence, linear processing is nearly optimal. A huge throughput and energy efficiency can be achieved due to the multiplexing gain and the array gain. In particular, with a simple power control scheme, Massive MIMO can offer uniformly good service for all users. In this dissertation, we focus on the performance of Massive MIMO. The dissertation consists of two main parts: fundamentals and system designs of Massive MIMO. In the first part, we focus on fundamental limits of the system performance under practical constraints such as low complexity processing, limited length of each coherence interval, intercell interference, and finite-dimensional channels. We first study the potential for power savings of the Massive MIMO uplink with maximum-ratio combining (MRC), zero-forcing, and minimum mean-square error receivers, under perfect and imperfect channels. The energy and spectral efficiency tradeoff is investigated. Secondly, we consider a physical channel model where the angular domain is divided into a finite number of distinct directions. A lower bound on the capacity is derived, and the effect of pilot contamination in this finite-dimensional channel model is analyzed. Finally, some aspects of favorable propagation in Massive MIMO under Rayleigh fading and line-of-sight (LoS) channels are investigated. We show that both Rayleigh fading and LoS environments offer favorable propagation. In the second part, based on the fundamental analysis in the first part, we propose some system designs for Massive MIMO. The acquisition of channel state information (CSI) is very importantin Massive MIMO. Typically, the channels are estimated at the BS through uplink training. Owing to the limited length of the coherence interval, the system performance is limited by pilot contamination. To reduce the pilot contamination effect, we propose an eigenvalue-decomposition-based scheme to estimate the channel directly from the received data. The proposed scheme results in better performance compared with the conventional training schemes due to the reduced pilot contamination. Another important issue of CSI acquisition in Massive MIMO is how to acquire CSI at the users. To address this issue, we propose two channel estimation schemes at the users: i) a downlink "beamforming training" scheme, and ii) a method for blind estimation of the effective downlink channel gains. In both schemes, the channel estimation overhead is independent of the number of BS antennas. We also derive the optimal pilot and data powers as well as the training duration allocation to maximize the sum spectral efficiency of the Massive MIMO uplink with MRC receivers, for a given total energy budget spent in a coherence interval. Finally, applications of Massive MIMO in relay channels are proposed and analyzed. Specifically, we consider multipair relaying systems where many sources simultaneously communicate with many destinations in the same time-frequency resource with the help of a massive MIMO relay. A massive MIMO relay is equipped with many collocated or distributed antennas. We consider different duplexing modes (full-duplex and half-duplex) and different relaying protocols (amplify-and-forward, decode-and-forward, two-way relaying, and one-way relaying) at the relay. The potential benefits of massive MIMO technology in these relaying systems are explored in terms of spectral efficiency and power efficiency.

Download or read book Channel Estimation and Signal Detection for Wireless Relay written by Jun Ma and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless relay can be utilized to extend signal coverage, achieve spatial diversity by user cooperation, or shield mobile terminals from adverse channel conditions over the direct link. In a two-hop multi-input-multi-output (MIMO) amplify-and-forward (AF) relay system, the overall noise at the destination station (DS) consists of the colored noise forwarded from the relay station (RS) and the local white noise. We propose blind noise correlation estimation at the DS by utilizing statistics of the broadband relay channel over the RS-DS hop, which effectively improves signal detection at the DS. For further : performance improvement, we also propose to estimate the two cascaded MIMO relay channels over the source-RS and the RS-DS links at the DS based on the overall channel between the source and the DS and the amplifying matrix applied at the RS. To cancel cross-talk interference at a channel-reuse-relay-station (CRRS), we utilize the random forwarded signals of the CRRS as equivalent pilots for local coupling channel estimation and achieve a much higher post signal-to-interference ratio (SIR) than the conventional.

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 185 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.