Download or read book Agile Spectrum Sharing Wireless Systems Using Software Defined Radios and Reconfigurable Antennas written by Danh Huu Hoang Nguyen and published by . This book was released on 2017 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the radio spectrum is a scarce resource, to satisfy the future demand for wireless capacity, more efficient methods to utilize the spectrum are needed. The recent trend of migrating radio devices from ASIC hardware to a more software-based nature enables a host of new flexible applications. In addition, modern RF frontend and antenna technologies have matured in terms of processing bandwidth, frequency coverage, and reconfigurability to enable emerging capabilities, such as wideband sensing, beamforming, and adaptive transmission. These advances constitute significant system design elements that are still underutilized in practice for enhancing spectrum use and network capacity. In this research work, we propose to leverage these new system design elements to realize effective MAC/PHY cross-layer designs that can substantially increase wireless network capacity. Specifically, we address three system design issues: i) enhancing software radios for timing and frequency agility in spectrum sharing scenarios, ii) enabling synchronous and directional channel access in wireless LANs to handle congestion and interference, and iii) maximizing indoor spatial reuse through adaptive antenna beamsteering. Software-defined radios (SDRs) have become instrumental for experimental prototyping and evaluations of modern wireless technologies. Nevertheless, with their physical layer programmability, SDRs incorporates long and non-deterministic processing latencies that severely limits its utility in cross-layer MAC/PHY designs. Existing approaches to overcome this drawback tend to focus on either optimizing PHY software implementations with highly specialized techniques, or moving the entire PHY onto reconfigurable hardware (FPGAs and DSPs). These solutions inadvertently make reprogramming the radio layer becomes a complex and time-consuming task. We propose an extension of the recently emerged split-functionality architecture to enhance the timing and frequency agility of SDRs specifically for spectrum sharing applications. The key idea is to split MAC and PHY functionalities for hardware/software co-processing, with all time-critical functionalities implemented in hardware for low latency and deterministic timing, and all non-time-critical parts remaining in software for flexibility. We demonstrate the effectiveness of this design pattern through two specific spectrum-agile operations: a protocol-aware reactive jamming radio, and a bandwidth-adaptive Orthogonal Frequency-Division Multiplexing (OFDM) communications system. Both experimental systems are verified to work consistently with prior studies and can serve as valuable instruments to investigate and develop agile spectrum-sharing techniques to enhance the spectral efficiency and security of cognitive radio networks. An undesired aspect of widespread wireless adoption is the chaotic, unplanned, and unmanaged deployments of wireless devices, especially in indoor environments. Existing wireless LAN protocols such as IEEE 802.11, however, scales poorly to handle the interference problem in dense networks. To address this problem, we design a novel synchronous directional wireless architecture that dramatically increase indoor wireless capacity using reconfigurable antennas. The core of this solution is an antenna orientation algorithm that applies reinforcement learning to consistently identify and track close-to-optimal antenna directions. In addition, this wireless design also incorporates a new Time Division Multiple Access (TDMA)-based channel access protocol that can ensure sub-microsecond synchronization among all wireless nodes, making it much more efficient than existing asynchronous 802.11 MACs in maintaining quality of service across the network at scale.

Download or read book Opportunistic Spectrum Sharing and White Space Access written by Oliver Holland and published by John Wiley & Sons. This book was released on 2015-04-22 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: Details the paradigms of opportunistic spectrum sharing and white space access as effective means to satisfy increasing demand for high-speed wireless communication and for novel wireless communication applications This book addresses opportunistic spectrum sharing and white space access, being particularly mindful of practical considerations and solutions. In Part I, spectrum sharing implementation issues are considered in terms of hardware platforms and software architectures for realization of flexible and spectrally agile transceivers. Part II addresses practical mechanisms supporting spectrum sharing, including spectrum sensing for opportunistic spectrum access, machine learning and decision making capabilities, aggregation of spectrum opportunities, and spectrally-agile radio waveforms. Part III presents the ongoing work on policy and regulation for efficient and reliable spectrum sharing, including major recent steps forward in TV White Space (TVWS) regulation and associated geolocation database approaches, policy management aspects, and novel licensing schemes supporting spectrum sharing. In Part IV, business and economic aspects of spectrum sharing are considered, including spectrum value modeling, discussion of issues around disruptive innovation that are pertinent to opportunistic spectrum sharing and white space access, and business benefits assessment of the novel spectrum sharing regulatory proposal Licensed Shared Access. Part V discusses deployments of opportunistic spectrum sharing and white space access solutions in practice, including work on TVWS system implementations, standardization activities, and development and testing of systems according to the standards. Discusses aspects of pioneering standards such as the IEEE 802.22 “Wi-Far” standard, the IEEE 802.11af “White-Fi” standard, the IEEE Dynamic Spectrum Access Networks Standards Committee standards, and the ETSI Reconfiguration Radio Systems standards Investigates regulatory and regulatory-linked solutions assisting opportunistic spectrum sharing and white space access, including geo-location database approaches and licensing enhancements Covers the pricing and value of spectrum, the economic effects and potentials of such technologies, and provides detailed business assessments of some particularly innovative regulatory proposals The flexible and efficient use of radio frequencies is necessary to cater for the increasing data traffic demand worldwide. This book addresses this necessity through its extensive coverage of opportunistic spectrum sharing and white space access solutions. Opportunistic Spectrum Sharing and White Space Access: The Practical Reality is a great resource for telecommunication engineers, researchers, and students.

Download or read book Cognitive Radio Software Defined Radio and Adaptive Wireless Systems written by Hüseyin Arslan and published by Springer Science & Business Media. This book was released on 2007-09-05 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today’s wireless services have come a long way since the roll out of the conventional voice-centric cellular systems. The demand for wireless access in voice and high rate data multi-media applications has been increasing. New generation wireless communication systems are aimed at accommodating this demand through better resource management and improved transmission technologies. The interest in increasing Spectrum Access and improving Spectrum Efficiency combined with both the introduction of Software Defined Radios and the realization that machine learning can be applied to radios has created new intriguing possibilities for wireless radio researchers. This book is aimed to discuss the cognitive radio, software defined radio (SDR), and adaptive radio concepts from several aspects. Cognitive radio and cognitive networks will be investigated from a broad aspect of wireless communication system enhancement while giving special emphasis on better spectrum utilization. Applications of cognitive radio, SDR and cognitive radio architectures, spectrum efficiency and soft spectrum usage, adaptive wireless system design, measurements and awareness of various parameters including interference temperature and geo-location information are some of the important topics that will be covered in this book. Cognitive Radio, Software Defined Radio, and Adaptive Wireless Systems is intended to be both an introductory technology survey/tutorial for beginners and an advanced mathematical overview intended for technical professionals in the communications industry, technical managers, and researchers in both academia and industry.

Download or read book Spectrum Sharing written by Constantinos B. Papadias and published by John Wiley & Sons. This book was released on 2020-03-13 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combines the latest trends in spectrum sharing, both from a research and a standards/regulation/experimental standpoint Written by noted professionals from academia, industry, and research labs, this unique book provides a comprehensive treatment of the principles and architectures for spectrum sharing in order to help with the existing and future spectrum crunch issues. It presents readers with the most current standardization trends, including CEPT / CEE, eLSA, CBRS, MulteFire, LTE-Unlicensed (LTE-U), LTE WLAN integration with Internet Protocol security tunnel (LWIP), and LTE/Wi-Fi aggregation (LWA), and offers substantial trials and experimental results, as well as system-level performance evaluation results. The book also includes a chapter focusing on spectrum policy reinforcement and another on the economics of spectrum sharing. Beginning with the historic form of cognitive radio, Spectrum Sharing: The Next Frontier in Wireless Networks continues with current standardized forms of spectrum sharing, and reviews all of the technical ingredients that may arise in spectrum sharing approaches. It also looks at policy and implementation aspects and ponders the future of the field. White spaces and data base-assisted spectrum sharing are discussed, as well as the licensed shared access approach and cooperative communication techniques. The book also covers reciprocity-based beam forming techniques for spectrum sharing in MIMO networks; resource allocation for shared spectrum networks; large scale wireless spectrum monitoring; and much more. Contains all the latest standardization trends, such as CEPT / ECC, eLSA, CBRS, MulteFire, LTE-Unlicensed (LTE-U), LTE WLAN integration with Internet Protocol security tunnel (LWIP) and LTE/Wi-Fi aggregation (LWA) Presents a number of emerging technologies for future spectrum sharing (collaborative sensing, cooperative communication, reciprocity-based beamforming, etc.), as well as novel spectrum sharing paradigms (e.g. in full duplex and radar systems) Includes substantial trials and experimental results, as well as system-level performance evaluation results Contains a dedicated chapter on spectrum policy reinforcement and one on the economics of spectrum sharing Edited by experts in the field, and featuring contributions by respected professionals in the field world wide Spectrum Sharing: The Next Frontier in Wireless Networks is highly recommended for graduate students and researchers working in the areas of wireless communications and signal processing engineering. It would also benefit radio communications engineers and practitioners.

Download or read book Sharing RF Spectrum with Commodity Wireless Technologies written by Jan Kruys and published by Springer Science & Business Media. This book was released on 2011-08-09 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much energy has been spent on the subject of spectrum scarcity that would threaten to stunt the growth of wireless technologies and services. This concern comes on the heels of the great successes of both cellular communications and consumer oriented communications like Wi-Fi and Bluetooth that have changed the way people use computers and communications and that have led to the creation of large new markets for products and services. The response of many spectrum regulators throughout the world in addressing these concerns has been to consider releasing more spectrum for unlicensed or for shared use. An example is the spectrum that is released by the transition to digital TV: the frequencies freed up are destined, in part, to new applications that would be license exempt. A possible beneficiary of new spectrum releases would be "the smart grid", a networked application of digital sensor and control technology to the energy delivery segment of the energy utility industry. This policy has heightened the interests of all involved in spectrum sharing and many proposals are being considered or brought forward. However, theory in this area is scarce and practice proves resistive of quick solutions. A case in point is RLAN/radar spectrum sharing in the 5GHz range: six years after the ITU-R allocated this shared spectrum, the rules for sharing as well as the means to verify compliance with these rules are not fully mature. Another recent development is the interest in spectrum pricing and trading which tend to focus on the economic aspects of spectrum sharing at the expense understanding of the limitations as well as the technical possibilities of spectrum sharing.

Download or read book Spectrum Sharing in Cognitive Radio Networks written by Shweta Pandit and published by Springer. This book was released on 2017-04-12 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the use of the spectrum sharing techniques in cognitive radio technology, in order to address the problem of spectrum scarcity for future wireless communications. The authors describe a cognitive radio medium access control (MAC) protocol, with which throughput maximization has been achieved. The discussion also includes use of this MAC protocol for imperfect sensing scenarios and its effect on the performance of cognitive radio systems. The authors also discuss how energy efficiency has been maximized in this system, by applying a simple algorithm for optimizing the transmit power of the cognitive user. The study about the channel fading in the cognitive user and licensed user and power adaption policy in this scenario under peak transmit power and interference power constraint is also present in this book.

Download or read book Spectrum Sharing in Wireless Networks written by John D. Matyjas and published by CRC Press. This book was released on 2016-11-17 with total page 697 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectrum Sharing in Wireless Networks: Fairness, Efficiency, and Security provides a broad overview of wireless network spectrum sharing in seven distinct sections: The first section examines the big picture and basic principles, explaining the concepts of spectrum sharing, hardware/software function requirements for efficient sharing, and future trends of sharing strategies. The second section contains more than 10 chapters that discuss differing approaches to efficient spectrum sharing. The authors introduce a new coexistence and sharing scheme for multi-hop networks, describe the space-time sharing concept, introduce LTE-U, and examine sharing in broadcast and unicast environments. They then talk about different cooperation strategies to achieve mutual benefits for primary users (PU) and secondary users (SU), discuss protocols in a spectrum sharing context, and provide different game theory models between PUs and SUs. The third section explains how to model the interactions of PUs and SUs, using an efficient calculation method to determine spectrum availability. Additionally, this section explains how to use scheduling models to achieve efficient SU traffic delivery. The subject of the fourth section is MIMO-oriented design. It focuses on how directional antennas and MIMO antennas greatly enhance wireless network performance. The authors include a few chapters on capacity/rate calculations as well as beamforming issues under MIMO antennas. Power control is covered in the fifth section which also describes the interference-aware power allocation schemes among cognitive radio users and the power control schemes in cognitive radios. The sixth section provides a comprehensive look at security issues, including different types of spectrum sharing attacks and threats as well as corresponding countermeasure schemes. The seventh and final section covers issues pertaining to military applications and examines how the military task protects its data flows when sharing the spectrum with civilian applications.

Download or read book Software Defined Radios from Base band Architecture to Reconfigurable Antennas written by Hamid Eslami and published by . This book was released on 2010 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal Frequency Division Multiple Access (OFDMA) paired with Multiple Input Multiple Output (MIMO) antenna techniques provide high diversity order along with high spectral efficiency. To enhance the performance of MIMO-OFDMA systems, several algorithms are used to mitigate the link imperfections as well as to recover transmitted information. To further improve performance, directional reconfigurable antennas with beam-tilting capability can be used. Performance gains in MIMO systems are highly dependent on the accurate representation of channel conditions. While simplified channel models are sufficient for initial performance characterizations, channel emulators provide the capability of emulating a vast variety of wireless channels in a lab environment. In this work, design and implementation of a broadband wireless channel emulator in the frequency domain is presented as an efficient and scalable alternative to the conventional Finite Impulse Response (FIR) based channel emulators for MIMO systems. It is shown that for a 3x3 MIMO array the proposed emulator results in 67% hardware reduction compared to the similarly constraint FIR-based emulator. Furthermore, to compare and quantify the effectiveness of different algorithms, a platform supporting highly modular MIMO-OFDMA is essential. On such a platform, multiple algorithms can be used for the same purpose and their gains analyzed and compared. Also, when equipped with reconfigurable capabilities, the platform can be used as part of a Software Defined Radio (SDR) system to adapt its parameters and specs to the current state of the wireless channel. To this end, a MIMO-OFDMA platform was developed with a modular and reconfigurable architecture. Finally, the link performance enhancement by using directional reconfigurable antennas with beam-tilting capability is analyzed. It is shown that higher directivity of directional antennas when combined with an agile direction selection scheme results in higher capacity or lower Symbol Error Rate (SER) in the system. Also, the training overhead for direction selection for such antennas is quantified. To reduce this overhead several training schemes are proposed and their capacity performances are compared with the conventional exhaustive training scheme. In particular, it is shown that using the proposed Exhaustive Training at Reduced Frequency (ETRF) consistently results in a reduction in training overhead. It is also demonstrated that further reduction in training overhead is possible using statistical or MUSIC-based training schemes.

Download or read book Reconfigurable Radio Systems written by Maria Stella Iacobucci and published by John Wiley & Sons. This book was released on 2013-05-13 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covers the state of the art of the technology and standards for reconfigurable radio systems, from self organizing networks and cognitive radio, through to reconfigurable architectures for networks and terminals This timely book provides a standards-based view of the development, evolution, techniques and potential future scenarios for the deployment of reconfigurable radio systems. After an introduction to radiomobile and radio systems deployed in the access network, the book describes cognitive radio concepts and capabilities, which are the basis for reconfigurable radio systems. The self-organizing network features introduced in 3GPP standards are discussed and before IEEE 802.22, the first standard based on cognitive radio, is described. Then the ETSI reconfigurable radio systems functional architecture and the IEEE 1900.4 standard for reconfigurable radio are examined. Finally, the author presents new scenarios and future visions that reconfigurable radio systems may bring. Key features:- Examines the current standards based on cognitive and reconfigurable radio, and analyses future scenarios Includes a general overview of radiomobile (i.e. GSM, UMTS, HSPA, LTE) and wireless (i.e. WLAN, WPAN, WiMAX) network architectures Features an accompanying website features links and white papers

Download or read book Handbook of Research on Software Defined and Cognitive Radio Technologies for Dynamic Spectrum Management written by Kaabouch, Naima and published by IGI Global. This book was released on 2014-10-31 with total page 1064 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inadequate use of wireless spectrum resources has recently motivated researchers and practitioners to look for new ways to improve resource efficiency. As a result, new cognitive radio technologies have been proposed as an effective solution. The Handbook of Research on Software-Defined and Cognitive Radio Technologies for Dynamic Spectrum Management examines the emerging technologies being used to overcome radio spectrum scarcity. Providing timely and comprehensive coverage on topics pertaining to channel estimation, spectrum sensing, communication security, frequency hopping, and smart antennas, this research work is essential for use by educators, industrialists, and graduate students, as well as academicians researching in the field.

Download or read book Wireless Coexistence for Spectrum Sharing written by Hossein-Ali Safavi-Naeini and published by . This book was released on 2016 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much of the spectrum licensed for usage by the regulatory authorities remains idle or heavily underutilized. By allowing opportunistic access to these dormant resources, spectrum sharing promises to dramatically boost the supply of spectrum that is available for high bandwidth wireless communications. This shared access arrangement will lead to the expected coexistence of multiple wireless systems within the same frequency band giving rise to the study undertaken in this dissertation. Our work begins by considering TV Whitespaces (TVWS) which were the first major instance of spectrum sharing to be considered. We look at adapting the 802.11 WLAN standard for operation in TVWS bands by incorporating sensing into the Wi-Fi MAC layer. We use this study to explore the potential of Software Defined Radio systems and the role they play in spectrum sharing systems while identifying the challenges and pitfalls inherent in such implementations. Our focus then shifts to spectrum sharing in radar bands. First, we aim to shrink the exclusion regions (as defined by the NTIA) by inheriting from the techniques developed for TVWS. The key outcome of this work is to provide an analytic framework for the selection of Wi-Fi parameters than can deliver the desired radar protection performance. This framework supports the aim of maximum spectrum utilization by reducing the areas which are deprived of shared access to radar spectrum. The last major result in this dissertation is a detailed study into the impact of radars on communication systems. We present what is to our knowledge the first detailed look at the physical layer obstacles that hinder network throughput for devices deployed in radar bands. Looking at the two major broadband standards (IEEE 802.11 WLAN and 3GPP LTE), we identify vulnerabilities that would render networks inoperable in close proximity to radars before providing effective solutions to recover the desired performance. The line of investigation in this thesis furnishes some of the solutions that are necessary for the future success of spectrum sharing systems.

Download or read book Spectrum Sharing for Wireless Communications written by ChunSheng Xin and published by Springer. This book was released on 2015-02-26 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: This SpringerBrief presents intelligent spectrum sharing technologies for future wireless communication systems. It explains the widely used opportunistic spectrum access and TV white space sharing, which has been approved by the FCC. Four new technologies to significantly increase the efficiency of spectrum sharing are also introduced. The four technologies presented are Dynamic Spectrum Co-Access, Incentivized Cooperative Spectrum Sharing, On-Demand Spectrum Sharing and Licensed Shared Spectrum Access. These technologies shed light on future wireless communication systems and pave the way for innovative spectrum sharing with increased spectrum utilization. Increased utilization will allow networks to meet the demand for radio spectrum and promote the growth of wireless industry and national economy. Spectrum Sharing is a valuable resource for researchers and professionals working in wireless communications. Advanced-level students in electrical engineering and computer science will also find this content helpful as a study guide.

Download or read book Spectrum Sharing in Cognitive Radio Networks written by Ghanshyam Singh and published by John Wiley & Sons. This book was released on 2021-05-27 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: SPECTRUM SHARING IN COGNITIVE RADIO NETWORKS Discover the latest advances in spectrum sharing in wireless networks from two internationally recognized experts in the field Spectrum Sharing in Cognitive Radio Networks: Towards Highly Connected Environments delivers an in-depth and insightful examination of hybrid spectrum access techniques with advanced frame structures designed for efficient spectrum utilization. The accomplished authors present the energy and spectrum efficient frameworks used in high-demand distributed architectures by relying on the self-scheduled medium access control (SMC-MAC) protocol in cognitive radio networks. The book begins with an exploration of the fundamentals of recent advances in spectrum sharing techniques before moving onto advanced frame structures with spectrum accessing approaches and the role of spectrum prediction and spectrum monitoring to eliminate interference. The authors also cover spectrum mobility, interference, and spectrum management for connected environments in substantial detail. Spectrum Sharing in Cognitive Radio Networks: Towards Highly Connected Environments offers readers a recent and rational theoretical mathematical model of spectrum sharing strategies that can be used for practical simulation of future generation wireless communication technologies. It also highlights ongoing trends, revealing fresh research outcomes that will be of interest to active researchers in the area. Readers will also benefit from: An inclusive study of connected environments, 3GPP Releases, and the evolution of wireless communication generations with a discussion of advanced frame structures and access strategies in cognitive radio networks A treatment of cognitive radio networks using spectrum prediction and monitoring techniques An analysis of the effects of imperfect spectrum monitoring on cognitive radio networks An exploration of spectrum mobility in cognitive radio networks using spectrum prediction and monitoring techniques An examination of MIMO-based CR-NOMA communication systems for spectral and interference efficient designs Perfect for senior undergraduate and graduate students in Electrical and Electronics Communication Engineering programs, Spectrum Sharing in Cognitive Radio Networks: Towards Highly Connected Environments will also earn a place in the libraries of professional engineers and researchers working in the field, whether in private industry, government, or academia.

Download or read book Temporal and Spatial Spectrum Reuse Among Heterogeneous Systems written by Sheng-Hui Liao and published by . This book was released on 2010 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: The wireless communication spectrum has increasingly become a scarce real estate in the modern information era. On one hand, the Radio Frequency (RF) bands are gradually being handled out for various wireless systems, and on the other, the RF bands might have been allocated conservatively at the beginning, thus causing underutilization problems in the current spectrum allocations. In this dissertation, system design choices for spectrum sharing from multiple perspectives are discussed, and temporal spectrum sharing and spatial spectrum sharing approaches are proposed to improve spectrum utilization efficiency. The temporal spectrum sharing approach interleaves the channel access among multiple wireless systems in a Time Division Multiple Access (TDMA) fashion. Different from cognitive radio approaches which are opportunistic and non-collaborative in general, temporal spectrum sharing proactively structures and interleaves the channel access moments of heterogeneous wireless systems with collaborative designs. A crucial architectural component -- the base stations of wireless systems is modified to implement temporal spectrum sharing, using Software-Defined Radios (SDRs). The spatial spectrum sharing approach follows the traditional wisdom of cognitive radios by categorizing wireless systems as primary and secondary users, and exploits the fact that some well-established wireless systems have asymmetric characteristics in spectrum band utilization and wireless station deployment, suitable for the coexistence of secondary systems. Specifically, the widely accepted and deployed GSM and WiFi systems as primary and secondary users, respectively, are examined. The coexistence of GSM and WiFi systems causes negligible interference with each other without spectrum sensing or monitoring complexities. Experimental results show that the proposed approaches are feasible approaches to the spectrum scarcity problem.

Download or read book Enhancing Multi User Wireless Networks with Pattern Reconfigurable Antennas written by Simon Begashaw and published by . This book was released on 2019 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: The explosive demand for high data rates and the need ubiquitous wireless connectivity has led to the phenomenon of network densification, the deployment of large number of base station within a geographic area. Since the radio spectrum is limited, wireless transmissions need to share a common resource which results in interference. Interference in turn creates a bottleneck on the communication rate. Recently three breakthroughs have been made to increase the capacity of wireless networks while mitigating interference : multiple input multiple output (MIMO) beamforming, interference alignment (IA) and pattern reconfigurable antennas (PRA). While a great deal of progress has been made on understanding each individually, relatively little is known about how to use these techniques in combination to increase system performance. In this dissertation, we analyze and experimentally evaluate how these new technologies can be leveraged to enhance the rate performance of communication networks. Specifically, we address three problems: i) enhancing multi-user MIMO performance with PRA, ii) improving IA performance with PRA-based antenna selection, and iii) enabling practical blind IA with PRA. To understand the impact PRAs on MU-MIMO and IA, it is necessary to evaluate their performance through measurements. Simulation-based studies often reiterate over set of simplistic channel models and unrealistic assumptions. This dissertation focuses on a measurement-based evaluation approach. For each of these problems, a hardware testbed implementation and measurement methodology is developed for evaluating the performance of the aforementioned technologies through efficient and repeatable experiments. The first two major contributions of this dissertation focus on multi-user MIMO (MU-MIMO) and IA. While the theoretical rate gains of MU-MIMO and IA are substantial, the performance gains in practical systems and measured channels have been limited. One of the key limiting factors are spatially correlated user channels. In this work, we propose MU-MIMO and IA transmission schemes that leverage the pattern diversity provided by PRAs to mitigate the effects of spatial correlation in wireless channels. PRAs are capable of dynamically adjusting their radiation pattern, providing an additional degree of freedom that can be exploited to improve MU-MIMO and IA performance by treating the array configuration and radiation characteristics as additional components in the joint optimization of adaptive system parameters. We quantify the benefits of pattern diversity on the rate performance of MU-MIMO and IA systems through extensive measurements. Furthermore, we develop efficient antenna mode selection algorithms to realize those benefits without increasing the system complexity or overhead, making these techniques suitable for practical implementation. The third contribution of this dissertation focuses on a transmission technique known as blind IA. In contrast to MU-MIMO and conventional IA, blind IA is signaling scheme that suppresses interference in multi-user systems, without the knowledge of channel state information at the transmitter (CSIT). The key to performing IA without CSIT is the use of PRAs that are capable of dynamically switching among a fixed number of radiation patterns to introduce artificial fluctuations in the channel. In this dissertation, we develop a novel implementation of a blind IA system on a software defined radio platform where each of the receivers is equipped with a PRA. Our work provides the first experimental evaluation of PRA-based blind IA schemes and demonstrates significant gains in rate and reliability over traditional orthogonal transmission schemes such as TDMA.

Download or read book Software Defined Radio for Engineers written by Alexander M. Wyglinski and published by Artech House. This book was released on 2018-04-30 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on the popular Artech House classic, Digital Communication Systems Engineering with Software-Defined Radio, this book provides a practical approach to quickly learning the software-defined radio (SDR) concepts needed for work in the field. This up-to-date volume guides readers on how to quickly prototype wireless designs using SDR for real-world testing and experimentation. This book explores advanced wireless communication techniques such as OFDM, LTE, WLA, and hardware targeting. Readers will gain an understanding of the core concepts behind wireless hardware, such as the radio frequency front-end, analog-to-digital and digital-to-analog converters, as well as various processing technologies. Moreover, this volume includes chapters on timing estimation, matched filtering, frame synchronization message decoding, and source coding. The orthogonal frequency division multiplexing is explained and details about HDL code generation and deployment are provided. The book concludes with coverage of the WLAN toolbox with OFDM beacon reception and the LTE toolbox with downlink reception. Multiple case studies are provided throughout the book. Both MATLAB and Simulink source code are included to assist readers with their projects in the field.

Download or read book Adaptive Transmission Schemes for Spectrum Sharing Systems written by Zied Bouida and published by . This book was released on 2015 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cognitive radio (CR) represents a key solution to the existing spectrum scarcity problem. Under the scenario of CR, spectrum sharing systems allow the coexistence of primary users (PUs) and secondary users (SUs) in the same spectrum as long as the interference from the secondary to the primary link stays below a given threshold. In this thesis, we propose a number of adaptive transmission schemes aiming at improving the performance of the secondary link in these systems while satisfying the interference constraint set by the primary receiver (PR). In the proposed techniques, the secondary transmitter (ST) adapts its transmission settings based on the availability of the channel state information (CSI) of the secondary and the interference links. In this context, these schemes offer different performance tradeoffs in terms of spectral efficiency, energy efficiency, and overall complexity. In the first proposed scheme, power adaptation (PA) and adaptive modulation (AM) are jointly used with switched transmit diversity in order to increase the capacity of the secondary link while minimizing the average number of antenna switching. Then, the concept of minimum-selection maximum ratio transmission (MS-MRT) is proposed as an adaptive variation of maximum ratio transmission (MRT) in a spectrum sharing scenario in order to maximize the capacity of the secondary link while minimizing the average number of transmit antennas. In order to achieve this performance, MS-MRT assumes that the secondary's CSI (SCSI) is perfectly known at the ST, which makes this scheme challenging from a practical point of view. To overcome this challenge, another transmission technique based on orthogonal space time bloc codes (OSTBCs) with transmit antenna selection (TAS) is proposed. This scheme uses the full-rate full-diversity Alamouti scheme in an underlay CR scenario in order to maximize the secondary's transmission rate. While the solutions discussed above offer a considerable improvement in the performance of spectrum sharing systems, they generally experience a high overall system complexity and are not optimized to meet the tradeoff between spectral efficiency and energy efficiency. In order to address this issue, we consider using spatial modulation (SM) in order to come with a spectrum sharing system optimized in terms spectral efficiency and energy efficiency. Indeed, SM can be seen as one of the emerging and promising new technologies optimizing the communication system while reducing the energy consumption thanks to the use of a single radio frequency (RF) chain for transmission. In this context, we propose the adaptive spatial modulation (ASM) scheme using AM in order to improve the spectral efficiency of SM. We also extend ASM to spectrum sharing systems by proposing a number of ASM-CR schemes aiming at improving the performance of these systems in terms of spectral efficiency and energy efficiency. While the use of a single RF-chain improves the energy efficiency of the above schemes, the RF-chain switching process between different transmissions comes with additional complexity and implementation issues. To resolve these issues, we use the concept of reconfigurable antennas (RAs) in order to improve the performance of space shift keying (SSK). In this context, employing RAs with SSK instead of conventional antennas allows for implementing only one RF chain and selecting different antenna-states for transmission without the need for RF switching. Moreover, the reconfigurable properties of RAs can be used as additional degrees of freedom in order to enhance the performance of SSK in terms of throughput, system complexity, and error performance. These RAs-based schemes are also extended to spectrum sharing systems in order to improve the capacity of the secondary link while reducing the energy consumption and the implementation complexity of the SU. In summary, we propose in this thesis several adaptive transmission schemes for spectrum sharing systems. The performance of each of these schemes is confirmed via Monte-Carlo simulations and analytical results and is shown to offer different tradeoffs in terms of spectral efficiency, energy efficiency, reliability, and implementation complexity. In this context, these proposed schemes offer different solutions in order to improve the performance of underlay cognitive radio systems.