Download or read book Utilizing Channel State Information for Enhancement of Wireless Communication Systems written by Abdorreza Heidari and published by . This book was released on 2007 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the fundamental limitations of mobile radio communications is their time-varying fading channel. This thesis addresses the efficient use of channel state information to improve the communication systems, with a particular emphasis on practical issues such as compatibility with the existing wireless systems and low complexity implementation. The closed-loop transmit diversity technique is used to improve the performance of the downlink channel in MIMO communication systems. For example, the WCDMA standard endorsed by 3GPP adopts a mode of downlink closed-loop scheme based on partial channel state information known as mode 1 of 3GPP. Channel state information is fed back from the mobile unit to the base station through a low-rate uncoded feedback bit stream. In these closed-loop systems, feedback error and feedback delay, as well as the sub-optimum reconstruction of the quantized feedback data, are the usual sources of deficiency. In this thesis, we address the efficient reconstruction of the beamforming weights in the presence of the feedback imperfections, by exploiting the residual redundancies in the feedback stream. We propose a number of algorithms for reconstruction of beamforming weights at the base-station, with the constraint of a constant transmit power. The issue of the decoding at the receiver is also addressed. In one of the proposed algorithms, channel fading prediction is utilized to combat the feedback delay. We introduce the concept of Blind Antenna Verification which can substitute the conventional Antenna Weight Verification process without the need for any training data. The closed-loop mode 1 of 3GPP is used as a benchmark, and the performance is examined within a WCDMA simulation framework. It is demonstrated that the proposed algorithms have substantial gain over the conventional method at all mobile speeds, and are suitable for the implementation in practice. The proposed approach is applicable to other closed-loop schemes as well. The problem of (long-range) prediction of the fading channel is also considered, which is a key element for many fading-compensation techniques. A linear approach, usually used to model the time evolution of the fading process, does not perform well for long-range prediction applications. We propose an adaptive algorithm using a state-space approach for the fading process based on the sum-sinusoidal model. Also to enhance the widely-used linear approach, we propose a tracking method for a multi-step linear predictor. Comparing the two methods in our simulations shows that the proposed algorithm significantly outperforms the linear method, for both stationary and non-stationary fading processes, especially for long-range predictions. The robust structure, as well as the reasonable computational complexity, makes the proposed algorithm appealing for practical applications.

Download or read book Efficient Utilization of Channel State Information in Modern Wireless Communication Systems written by Cong Shen and published by . This book was released on 2009 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical Layer Approaches for Securing Wireless Communication Systems written by Hong Wen and published by Springer Science & Business Media. This book was released on 2013-02-14 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book surveys the outstanding work of physical-layer (PHY) security, including the recent achievements of confidentiality and authentication for wireless communication systems by channel identification. A practical approach to building unconditional confidentiality for Wireless Communication security by feedback and error correcting code is introduced and a framework of PHY security based on space time block code (STBC) MIMO system is demonstrated. Also discussed is a scheme which combines cryptographic techniques implemented in the higher layer with the physical layer security approach using redundant antennas of MIMO systems to provide stronger security for wireless networks. The channel responses between communication peers have been explored as a form of fingerprint with spatial and temporal uniqueness. Finally, the book develops a new lightweight method of channel identification for Sybil attack and node clone detection in wireless sensor networks (WSNs).

Download or read book Physical layer Security Enhancement in Wireless Communication Systems written by Hao Li and published by . This book was released on 2013 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Without any doubt, wireless infrastructures and services have fundamental impacts on every aspect of our lives. Despite of their popularities, wireless communications are vulnerable to various attacks due to the open nature of radio propagation. In fact, communication security in wireless networks is becoming more critical than ever. As a solution, conventional cryptographic techniques are deployed on upper layers of network protocols. Along with direct attacks from lower layer, wireless security challenges come with the rapid evolution of sophisticated decipher techniques. Conventional security mechanisms are not necessarily effective against potential attacks from the open wireless environment anymore. As an alternative, physical-layer(PHY) security, utilizing unique features from lower layer, becomes a new research focus for many wireless communication systems. In this thesis, three mechanisms for PHY security enhancement are investigated. Beginning with a discussion on the security vulnerability in highly standardized infrastructures, the thesis proposed a time domain scrambling scheme of orthogonal frequency division multiplexing (OFDM) system to improve the PHY security. The method relies on secretly scrambling each OFDM symbol in time domain, resulting in constellation transformation in frequency domain, to hide transmission features. As a complement to existing secrecy capacity maximization based optimal cooperative jamming systems, a security strategy based on the compromised secrecy region (CSR) minimization in cooperative jamming is then proposed when instantaneous channel state information(CSI) is not available. The optimal parameters of the jammer are derived to minimize the CSR which exhibits high secrecy outage probability. At last, security enhancement of OFDM system in cooperative networks is also investigated. The function selection strategies of cooperative nodes are studied. Our approach is capable of enhancing the security of broadband communications by selecting the proper function of each cooperative node. Numerical results demonstrate the feasibility of three proposed physical layer security mechanisms by examining the communication reliability, achievable CSR and secrecy capacity respectively.

Download or read book Next Generation Wireless Communications Using Radio over Fiber written by Nathan J. Gomes and published by John Wiley & Sons. This book was released on 2012-08-15 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Taking a coherent and logical approach, this book describes the potential use of co-ordinated multipoint systems supported by radio over fiber. It covers an impressive breadth of topics, ranging from components, subsystem and system architecture, to network management and business perspectives. The authors show the importance of radio over fiber in eliminating or mitigating against the current, perceived barriers to the use of co-ordinated multipoint, and the drivers for standardisation activities in future mobile/wireless systems over the next few years. The book brings together the system concept for centralized processing, including what is required for co-existence with legacy wireless systems, the algorithms that can be used for improving wireless bandwidth utilization at physical and MAC layers and the radio over fiber network and link design necessary to support the wireless system. Other important research is also covered as the authors look at compensating for radio over fiber impairments and providing simple network management functions. A study of service provision and the business case for such a future wireless system is also fully considered. This book comes at an important time for future wireless systems with standardization of fourth generation wireless systems still ongoing. The content enables readers to make key decisions about future standardisation and their own research work. The business analysis also makes the book useful to those involved in deciding the future directions of telecoms organisations. This information will be core to their decision-making as it provides technical knowledge of the state-of-the-art but also system level assessments of what is possible in a business environment.

Download or read book Fundamentals of Wireless Communication written by David Tse and published by Cambridge University Press. This book was released on 2005-05-26 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook takes a unified view of the fundamentals of wireless communication and explains cutting-edge concepts in a simple and intuitive way. An abundant supply of exercises make it ideal for graduate courses in electrical and computer engineering and it will also be of great interest to practising engineers.

Download or read book Limited Feedback of Channel State Information in Wireless Communication Systems written by Bo Zhao and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wireless Communications written by Prathima Agrawal and published by Springer Science & Business Media. This book was released on 2010-05-05 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains papers based on invited talks given at the 2005 IMA Summer Workshop on Wireless Communications, held at the Institute for Mathematics and Its Applications, University of Minnesota, June 22 - July 1, 2005. It presents some of the highlights of the workshop, and collects papers covering a broad spectrum of important and pressing issues in wireless communications.

Download or read book Towards Increasing the Capacity in MIMO Wireless Communication Systems written by Seyed Alireza Banani and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of multiple antennas on both sides of a multipath channel can improve the capacity without additional transmit power. It is possible, in principle, for the capacity to increase linearly with the number of antennas even when the channel state information (CSI) is unknown at the transmitter. These known capacity results require many assumptions, including the need for the CSI to be known perfectly. In practice, perfect CSI is never known perfectly a priori, and its estimation, without using an ideal blind technique (none are available), requires bandwidth resource which reduces the capacity. Moreover, various factors such as digital modulation, finite block lengths, and imperfect power allocation degrade the capacity from the Shannon limit to the practicable possibilities of a digital link. These practical impairments motivate new techniques for increasing the capacity in MIMO systems, and in this thesis, two sets of techniques are presented. The first set includes two new decision-directed techniques for estimating the channel matrix, and they are shown to have higher capacity compared to pilot symbol assisted modulation systems since no pilots are required. These techniques are applicable for various open-loop SISO/MIMO wireless communications systems including systems employing OFDM, nonlinear/linear equalization, MRC, Alamouti coding, and spatial multiplexing. In the second set, the eigen-MIMO capacity is maximized in the presence of different practical impairments. In particular, the joint influence of training-based channel estimation and imperfect feedback on both the information-theoretic and the practicable water-filled eigen-MIMO capacities, are analyzed. Water-filled eigenchannels maximize the information theoretic capacity, but for implementation, the required adaptive modulation means high complexity. One simplification is to have fixed modulation over a fixed number of eigenchannels. However, the error rate deteriorates with the weakest eigenchannel and to counter this while maintaining high throughput, the information rate is maximized with an output SNR constraint. On the other hand, if higher complexity can be tolerated, adaptive modulation and coding can be deployed for high throughput. In this context, a high capacity eigen-MIMO system using Reed-Solomon coded M-QAM is developed. This includes an appropriate QAM, code rate, and power allocation for each eigenchannel.

Download or read book Wireless Powered Communication Networks written by Abbas Jamalipour and published by Springer. This book was released on 2018-10-12 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook introduces Wireless Powered Communication Networks (WPCNs) as a promising paradigm to overcome the energy bottleneck suffered by traditional wireless communication networks, as well as emerging Internet-of-Things networks. It selectively spans a coherent spectrum of fundamental aspects in WPCNs, such as wireless energy transfer (WEH) techniques, radio frequency (RF) energy harvesting receiver model, simultaneous wireless information and power transfer (SWIPT), as well as the rate-energy tradeoff arising from the joint transmission of information and energy using the same waveform. It covers network models for WPCNs, including the baseline and dual-hop WPCN models and a variety of related extensions. This book further examines the key factors including throughput, fairness, and security that must be taken into account for impeccable operation of WPCNs. The new IoT applications are targeted as a key element in those factors. It will also include exercises and examples throughout the book, as well as their PLS solutions. This is the first textbook examining the current research to provide a unified view of wireless power transfer (WPT) and information transmission in WPCNs from a physical layer security (PLS) perspective. Focused on designing efficient secure transmission schemes, analyzing energy evolvement process, and evaluating secrecy outage performance under different channel state information (CSI), the results presented in this book shed light on how to best balance security and throughput with prudent use of harvested energy in WCNs. It also provides an overview of the WPCNs by introducing the background of WPT, followed by a summary of the research conducted in the field. The authors describe the physical-layer security (PLS) problem in WPCNs, including the causes and the impacts of the problem on the performance of WPCNs. The authors extend the discussions by introducing the applications of WPCNs in the IoT. From the Internet of Things (IoT) point of view, this textbook reviews the opportunities and challenges for the lately-emerged WPCN to seamlessly integrate into the IoT ecosystem. It specifically addresses the maximization problem of uplink and downlink sum-throughout in a dual-hop WPCN, while taking fairness among WPCN users as a constraint. The results provided in this book reveal valuable insights into improving the design and deployment of future WPCNs in the upcoming IoT environment. This textbook targets advanced-level students studying wireless communications and research engineers working in this field. Industry engineers in mobile device and network development business with an interest in WPCNs and IoT, as well as their PLS solutions, will also find this book useful.

Download or read book mmWave Massive MIMO written by Shahid Mumtaz and published by Academic Press. This book was released on 2016-12-02 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: mmWave Massive MIMO: A Paradigm for 5G is the first book of its kind to hinge together related discussions on mmWave and Massive MIMO under the umbrella of 5G networks. New networking scenarios are identified, along with fundamental design requirements for mmWave Massive MIMO networks from an architectural and practical perspective. Working towards final deployment, this book updates the research community on the current mmWave Massive MIMO roadmap, taking into account the future emerging technologies emanating from 3GPP/IEEE. The book's editors draw on their vast experience in international research on the forefront of the mmWave Massive MIMO research arena and standardization. This book aims to talk openly about the topic, and will serve as a useful reference not only for postgraduates students to learn more on this evolving field, but also as inspiration for mobile communication researchers who want to make further innovative strides in the field to mark their legacy in the 5G arena. - Contains tutorials on the basics of mmWave and Massive MIMO - Identifies new 5G networking scenarios, along with design requirements from an architectural and practical perspective - Details the latest updates on the evolution of the mmWave Massive MIMO roadmap, considering future emerging technologies emanating from 3GPP/IEEE - Includes contributions from leading experts in the field in modeling and prototype design for mmWave Massive MIMO design - Presents an ideal reference that not only helps postgraduate students learn more in this evolving field, but also inspires mobile communication researchers towards further innovation

Download or read book Spatial Interference Cancellation and Channel Estimation for Multiple input Multiple output Wireless Communication Systems written by Chaiyod Pirak and published by . This book was released on 2005 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multiple-input multiple-output (MIMO) wireless communication system is one of prominent systems for realizing high data-rate transmission services highly demanded in the future wireless communications. It can provide a significant performance enhancement to the wireless communications, including increased data rates through a multiplexing gain, an enhanced error probability through a diversity gain, and cancellation of multiple access interference through smart antennas. However, for such system employing coherent receivers, an accurate channel state information is crucially needed. These performance advantages and challenge, respectively, are the motivations of this dissertation. In the first part of this dissertation, a novel smart antenna system for interference canceling receivers in direct-sequence code-division multiple access (DS-CDMA) systems is proposed. This proposed scheme only exploits the spreading codes of users as the information forits weight adjustment for controlling its beam. This proposed scheme is also robust to the in-beam interference, especially in the near-far effect situation. Convergence and error probability performance analysis is also carried out. Theoretical and simulation results indicate that the proposed scheme outperforms the existing works.

Download or read book The Use of Channel State Information in Wireless Communication written by Srihari Adireddy and published by . This book was released on 2003 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Signal Processing Aspects of Cell Free Massive MIMO written by Giovanni Interdonato and published by Linköping University Electronic Press. This book was released on 2019-03-20 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fifth generation of mobile communication systems (5G) promises unprecedented levels of connectivity and quality of service (QoS) to satisfy the incessant growth in the number of mobile smart devices and the huge increase in data demand. One of the primary ways 5G network technology will be accomplished is through network densification, namely increasing the number of antennas per site and deploying smaller and smaller cells. Massive MIMO, where MIMO stands for multiple-input multiple-output, is widely expected to be a key enabler of 5G. This technology leverages an aggressive spatial multiplexing, from using a large number of transmitting/receiving antennas, to multiply the capacity of a wireless channel. A massive MIMO base station (BS) is equipped with a large number of antennas, much larger than the number of active users. The users are coherently served by all the antennas, in the same time-frequency resources but separated in the spatial domain by receiving very directive signals. By supporting such a highly spatially-focused transmission (precoding), massive MIMO provides higher spectral and energy efficiency, and reduces the inter-cell interference compared to existing mobile systems. The inter-cell interference is however becoming the major bottleneck as we densify the networks. It cannot be removed as long as we rely on a network-centric implementation, since the inter-cell interference concept is inherent to the cellular paradigm. Cell-free massive MIMO refers to a massive MIMO system where the BS antennas, herein referred to as access points (APs), are geographically spread out. The APs are connected, through a fronthaul network, to a central processing unit (CPU) which is responsible for coordinating the coherent joint transmission. Such a distributed architecture provides additional macro-diversity, and the co-processing at multiple APs entirely suppresses the inter-cell interference. Each user is surrounded by serving APs and experiences no cell boundaries. This user-centric approach, combined with the system scalability that characterizes the massive MIMO design, constitutes a paradigm shift compared to the conventional centralized and distributed wireless communication systems. On the other hand, such a distributed system requires higher capacity of back/front-haul connections, and the signal co-processing increases the signaling overhead. In this thesis, we focus on some signal processing aspects of cell-free massive MIMO. More specifically, we firstly investigate if the downlink channel estimation, via downlink pilots, brings gains to cell-free massive MIMO or the statistical channel state information (CSI) knowledge at the users is enough to reliably perform data decoding, as in conventional co-located massive MIMO. Allocating downlink pilots is costly resource-wise, thus we also propose resource saving-oriented strategies for downlink pilot assignment. Secondly, we study further fully distributed and scalable precoding schemes in order to outperform cell-free massive MIMO in its canonical form, which consists in single-antenna APs implementing conjugate beamforming (also known as maximum ratio transmission).

Download or read book On Enhancements of Physical Layer Secret Key Generation and Its Application in Wireless Communication Systems written by Kang Liu and published by . This book was released on 2015 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: As an alternative and appealing approach to providing information security in wireless communication systems, secret key generation at physical layer has demonstrated its potential in terms of efficiency and reliability over traditional cryptographic methods. Without the necessity of a management centre for key distribution or reliance on computational complexity, physical layer key generation protocols enable two wireless entities to extract identical and dynamic keys from the randomness of the wireless channels associated with them. In this thesis, the reliability of secret key generation at the physical layer is examined in practical wireless channels with imperfect channel state information (CSI). Theoretical analyses are provided to relate key match rate with channel's signal-to-noise ratio (SNR), degrees of channel reciprocity, and iterations of information reconciliation. In order to increase key match rate of physical layer secret key generation, improved schemes in the steps of channel estimation and sample quantization are proposed respectively. In the channel estimation step, multiple observations of the wireless channels are integrated with a linear processor to provide a synthesized and more accurate estimation of the wireless channel. In the sample quantization step, a magnitude based quantization method with two thresholds is proposed to quantize partial samples, where specific quantization areas are selected to reduce cross-over errors. Significant improvements in key match rate are proven for both schemes in theoretical analysis and numerical simulations. Key match rate can even achieve 100% in both schemes with the assistance of information reconciliation process. In the end, a practical application of physical layer secret key generation is presented, where dynamic keys extracted from the wireless channels are utilized for securing secret data transmission and providing efficient access control.

Download or read book Optimizing Wireless Communication Systems written by Francisco Rodrigo Porto Cavalcanti and published by Springer Science & Business Media. This book was released on 2009-07-31 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt: In June 2000, GTEL (Wireless Telecommunications Research Group) at the F- eral University of Ceara ́ was founded by Professor Rodrigo Cavalcanti and his c- leagues with the mission of developing wireless communications technology and impact the development of the Brazilian telecommunications sector. From the start, this research effort has been supported by Ericsson Research providing a dynamic environment where academia and industry together can address timely and relevant research challenges. This book summarized much of the research output that has resulted from GTEL’s efforts. It provides a comprehensive treatment of the physical and multiple access layers in mobile communication systems describing different generations of systems but with a focus on 3G systems. The team of Professor C- alcanti has contributed scienti cally to the development of this eld and built up an impressive expertise. In the chapters that follow, they share their views and kno- edge on the underlying principles and technical trade-offs when designing the air interface of 3G systems. The complexity of 3G systems and the interaction between the physical and m- tiple access layers present a tremendous challenge when modeling, designing, and analyzing the mobile communication system. Herein, the authors tackle this pr- lem in an impressive manner. Their work is very much in line with the developments in 3GPP providing a deeper understanding of the evolution of 3G and also future enhancements.

Download or read book Next Generation Multiple Access written by Yuanwei Liu and published by John Wiley & Sons. This book was released on 2024-01-11 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: Highly comprehensive resource investigating how next-generation multiple access (NGMA) relates to unrestricted global connection, business requirements, and sustainable wireless networks Next Generation Multiple Access is a comprehensive, state-of-the-art, and approachable guide to the fundamentals and applications of next-generation multiple access (NGMA) schemes, guiding the future development of industries, government requirements, and military utilization of multiple access systems for wireless communication systems and providing various application scenarios to fit practical case studies. The scope and depth of this book are balanced for both beginners to advanced users. Additional references are provided for readers who wish to learn more details about certain subjects. Applications of NGMA outside of communications, including data and computing assisted by machine learning, protocol designs, and others, are also covered. Written by four leading experts in the field, Next Generation Multiple Access includes information on: Foundation and application scenarios for non-orthogonal multiple access (NOMA) systems, including modulation, detection, power allocation, and resource management NOMA’s interaction with alternate applications such as satellite communication systems, terrestrial-satellite communication systems, and integrated sensing Collision resolution, compressed sensing aided massive access, latency management, deep learning enabled massive access, and energy harvesting Holographic-pattern division multiple access, over-the-air transmission, multi-dimensional multiple access, sparse signal detection, and federated meta-learning assisted resource management Next Generation Multiple Access is an essential reference for those who are interested in discovering practical solutions using NGMA technology, including researchers, engineers, and graduate students in the disciplines of information engineering, telecommunications engineering, and computer engineering.