Download or read book Energy Constrained Link Adaptation for Multi hop Relay Networks written by Xiao Zhao and published by . This book was released on 2011 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless Sensor Network (WSN) is a widely researched technology that has applications in a broad variety of fields ranging from medical, industrial, automotive and pharmaceutical to even office and home environments. It is composed of a network of self-organizing sensor nodes that operate in complex environments without human intervention for long periods of time. The energy available to these nodes, usually in the form of a battery, is very limited. Consequently, energy saving algorithms that maximize the network lifetime are sought-after. Link adaptation polices can significantly increase the data rate and effectively reduce energy consumption. In this sense, they have been studied for power optimization in WSNs in recent research proposals. In this thesis, we first examine the Adaptive Modulation (AM) schemes for flat-fading channels, with data rate and transmit power varied to achieve minimum energy consumption. Its variant, Adaptive Modulation with Idle mode (AMI), is also investigated. An Adaptive Sleep with Adaptive Modulation (ASAM) algorithm is then proposed to dynamically adjust the operating durations of both the transmission and sleep stages based on channel conditions in order to minimize energy consumption. Furthermore, adaptive power allocation schemes are developed to improve energy efficiency for multi-hop relay networks. Experiments indicate that a notable reduction in energy consumption can be achieved by jointly considering the data rate and the transmit power in WSNs. The proposed ASAM algorithm considerably improves node lifetime relative to AM and AMI. Channel conditions play an important role in energy consumption for both AM and ASAM protocols. In addition, the number of modulation stages is also found to substantially affect energy consumption for ASAM. Node lifetime under different profiles of traffic intensity is also investigated. The optimal power control values and optimal power allocation factors are further derived for single-hop networks and multi-hop relay networks, respectively. Results suggest that both policies are more suitable for ASAM than for AM. Finally, the link adaptation techniques are evaluated based on the power levels of commercial IEEE 802.15.4-compliant transceivers, and ASAM consistently outperforms AM and AMI in terms of energy saving, resulting in substantially longer node lifetime.

Download or read book Link Adaptation for Energy Constrained Networks written by Ali Yildirim Alemdar and published by . This book was released on 2008 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Relay terminals are often used in tandem in sensor networks to lessen nodal communication burden. In this light we investigate the problem of power allocation amongst nodes in a relay network in order to maximize the overall achievable rate using link adaptive transmission protocols. We focus on the physical layer characteristics and implementation issues of link adaptation in order to develop a bit-level simulator needed to accurately model the rate performance of such a system. Optimal power allocation values, power adaptation policies, and switching levels for several link adaptive policies over a broad class of Rician fading channels are calculated. Furthermore, the maximum achievable rate for two and three link relay networks using our bit-level simulator and optimal power allocation values for collocated channel distributions is simulated. An overall achievable rate comparison between several link adaptive protocols is also investigated.

Download or read book Wireless Sensor Networks written by Mohamed Ibnkahla and published by CRC Press. This book was released on 2017-12-19 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: With classical techniques for data transmission soon reaching their limitations, cognitive approaches may offer a solution to user requirements for better coverage, connectivity, security, and energy efficiency at lower cost. Wireless Sensor Networks: A Cognitive Perspective presents a unified view of the state of the art of cognitive approaches in telecommunications. A benchmark in the field, it brings together research that has previously been scattered throughout conference and journal papers. Cutting-Edge Topics in Cognitive Communications After a review of the cognitive concept and approaches, the book outlines a generic architecture for cognition in wireless sensor networks. It then targets specific issues that need to be addressed through cognition, from cognitive radio and spectrum access to routing protocols. The book also explores how to use weighted cognitive maps to improve network lifetime through optimizing routing, medium access, and power control while fulfilling end-to-end goals. The final chapter discusses the implementation of hardware for GPS/INS-enabled wireless sensor networks. This addresses an important need for real-time node position information in many wireless sensor network applications and communication protocols. Real-World Applications of Wireless Sensor Networks using the Cognitive Concept Written in a tutorial style, the book supplies an in-depth survey of each topic, accompanied by detailed descriptions of the algorithms and protocols. It also provides a step-by-step analysis of the various communications systems through extensive computer simulations and illustrations. Examples cover environmental monitoring, vehicular communications, tracking, and more. A comprehensive overview of cognitive communications in wireless sensor networks, this work lays the foundations for readers to participate in a new era of research in this emerging field.

Download or read book Link Adaptation for Relay Based Cellular Networks written by Basak Can 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: Cover TextLink Adaptation for Relay-Based Cellular Networks focuses on the implementation of various link adaptation methods in OFDM(A) (Orthogonal Frequency Division Multiplexing/Multiple Access)?Time Division Duplex (TDD) based two-hop cellular networks. The analysis and design consider infrastructure based relays. New link adaptive transmission methods which dynamically select the channel coding, modulation, forwarding, relaying mechanisms and the packet size have been designed and evaluated for such networks. The selection among various schemes is based on maximizing the end-to-end throughput.This book provides a channel adaptive scheduler which considers the multiplexing loss caused by the two-phase nature of wireless relaying. The scheduler dynamically schedules the users on the frequency-time radio resources with efficient Modulation and Coding Schemes (MCS)s selected by Adaptive Modulation and Coding (AMC). Relaying is used only if it can provide throughput enhancement. The guidelines for efficient deployment of infrastructure based relay terminals are given. For the two-hop cellular communication systems, the system level performance of various cooperative diversity schemes has been investigated with the scheduler developed and the relays efficiently deployed in the cell. This investigation for low mobility scenarios shows that, a simple cooperative diversity scheme that dynamically chooses the best scheme among direct transmission and two-hop conventional relaying is a promising choice when compared to various more complex cooperative diversity schemes.In this book, a hop adaptive Medium Access Control (MAC)-Protocol Data Unit (PDU) size optimization is proposed for wireless relay networks.

Download or read book Ambient Backscatter Communication Networks written by Dinh Thai Hoang and published by Cambridge University Press. This book was released on 2020-04-30 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understand fundamental principles of ambient backscatter technology and their diverse potential applications with this authoritative review.

Download or read book Low complexity and Power efficient Wireless Cooperative Relay Networks with Enhanced Reliability written by Gi Wan Choi and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, global mobile data traffic has been increasing exponentially as mobile devices pervade our daily lives. To cope with the ever growing demands for higher data rates and seamless connectivity, one solution is to drastically increase the number of macro base stations in the conventional cellular architecture. However, this results in high deployment costs. Deploying low-power nodes such as relays that do not require a wired backhaul connection within a macrocell is one of cost-effective ways to extend high data rate coverage range. Relays are typically deployed to increase signal strength in poor coverage areas or to eliminate dead spots. But more importantly, relays provide a natural diversity, called cooperative diversity. In addition to a direct signal from a base station, extra copies of the same signal are forwarded from relays. Utilizing this diversity at the destination can yield significant performance enhancements. Thus, cooperative relay strategies need to be considered to enable high data rate coverage in a cost-effective manner. In this dissertation, we consider a simple single-relay network and present low-complexity and power-efficient cooperative relay designs that can achieve low error rate. We first study decode-and-forward (DF) relay networks with a single antenna at each node, where the relay decodes the received signal and forwards the re-encoded information to the destination. In DF relay scheme, decoding at the relay is not perfect and the error-propagation phenomenon is a detrimental problem, preventing the destination from collecting the cooperative diversity. To enable cooperative diversity in DF relay networks, we adopt link-adaptive power-scaling relay strategies where the relay scales the transmission power of the re-encoded signal based on the reliability of the source-relay link. We generalize power-profile designs and analyze the diversity order enabled by the general power-profile designs. We provide necessary and sufficient conditions for the designs to enable full cooperative diversity at the destination. In the second part of this dissertation, we extend the power-scaling relay strategy to DF multi-input multi-output (MIMO) relay networks, where multiple antennas are adopted at each node, and show that full cooperative diversity can also be achieved here. To collect spatial diversity provided by multiple antennas without using maximum-likelihood equalizers (MLEs) or near-ML detectors which exhibit high complexity, channel-controlled automatic repeat request (CC-ARQ) scheme is developed for DF MIMO relay networks to enable spatial diversity with linear equalizers (LEs) maintaining low-complexity. We also show that joint cooperative and spatial diversity can be achieved at the destination when the power-scaling strategy and the CC-ARQ with LEs are combined. Finally, amplify-and-forward (AF) MIMO relay designs, where the relay simply amplifies the received signal and forwards it to the destination, are studied with consideration of peak-power constraints at the relay. One practical concern for AF relaying is that the output signal at the relay may suffer from large peak-to-average power ratio (PAR), which may cause nonlinear distortion and/or saturation in the transmitted signal due to the limited linear range of power amplifiers. Thus, we first investigate peak-power constrained power-scaling strategies and find a sufficient condition to enable joint cooperative and spatial diversity at the destination. Based on this study, we propose simple and practical AF MIMO relay designs with peak-power constraint at the relay. CC-ARQ is also applied to AF MIMO relay networks to reduce the decoding complexity.

Download or read book Sustainable Wireless Networks written by Zhongming Zheng and published by Springer Science & Business Media. This book was released on 2013-10-07 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: This brief focuses on network planning and resource allocation by jointly considering cost and energy sustainability in wireless networks with sustainable energy. The characteristics of green energy and investigating existing energy-efficient green approaches for wireless networks with sustainable energy is covered in the first part of this brief. The book then addresses the random availability and capacity of the energy supply. The authors explore how to maximize the energy sustainability of the network and minimize the failure probability that the mesh access points (APs) could deplete their energy and put the network out of service due to the unreliable energy supply. This brief also studies network resource management issues in green wireless networks to minimize cost. It jointly considers the relay node (RN) placement and sub-carrier allocation (RNP-SA) issues in wireless networks with sustainable energy, and then formulates the problem into a mixed integer non-linear programming problem. Concise and informative, this brief is a useful resource for professionals or researchers studying wireless networks, communication networks, and energy efficiency. Advanced-level students interested in energy technology or communications engineering will also find the material valuable.

Download or read book Multi Hop Relay Networks written by David Soldani and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Green Radio Communication Networks written by Ekram Hossain and published by Cambridge University Press. This book was released on 2012-07-05 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents state-of-the-art research on green radio communications and networking technology to researchers and professionals working in wireless communication.

Download or read book Radio Resource Allocation Over Fading Channels Under Statistical Delay Constraints written by Tho Le-Ngoc and published by Springer. This book was released on 2017-05-10 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: This SpringerBrief presents radio resource allocation schemes for buffer-aided communications systems over fading channels under statistical delay constraints in terms of upper-bounded average delay or delay-outage probability. This Brief starts by considering a source-destination communications link with data arriving at the source transmission buffer. The first scenario, the joint optimal data admission control and power allocation problem for throughput maximization is considered, where the source is assumed to have a maximum power and an average delay constraints. The second scenario, optimal power allocation problems for energy harvesting (EH) communications systems under average delay or delay-outage constraints are explored, where the EH source harvests random amounts of energy from renewable energy sources, and stores the harvested energy in a battery during data transmission. Online resource allocation algorithms are developed when the statistical knowledge of the random channel fading, data arrivals, EH processes governing the system dynamics is unknown a-priori. This Brief continues with a source-relay-destination communications link with buffers available at both source and relay, as part of a multi-hop network. Optimal resource allocation schemes for this 3-node relaying system to maximize its effective capacity under a delay-outage constraint are proposed, with special emphasis on relay roles: Half-duplex (HD) or full-duplex (FD) relay operation. With HD relay, the adaptive link selection relaying problem jointly with both fixed and adaptive power allocation schemes is investigated. Within each transmission frame, either the source-relay link or the relay-destination link is selected to be active depending on the channel conditions. With FD relay under the presence of non-zero residual self-interference (SI). This Brief also presents source and relay power allocation schemes for both cases of available knowledge of the channel state information at transmitter (CSIT): instantaneous or statistical. Professional and researchers working in this related field and advanced-level students in electrical or computer engineering will find the content valuable as a reference.

Download or read book International Conference on Computer Applications Networking written by and published by Research Publishing Service. This book was released on with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mobile Lightweight Wireless Systems written by Periklis Chatzimisios and published by Springer Science & Business Media. This book was released on 2010-10-21 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following the success of the First MOBILIGHT 2009 in Athens, Greece, the Second International Conference on Mobile Lightweight Systems (MOBILIGHT) was held in Barcelona, Spain on May 10-12, 2010. It was not an easy decision to carry on organizing a scientific event on wireless communications, where competition is really enormous. This decision was motivated by discussion with many colleagues about the current unprecedented demand for lig- weight, wireless communication devices with high usability and performance able to support added-value services in a highly mobile environment. Such devices follow the users everywhere they go (at work, at home, while travelling, in a classroom, etc. ) and result in exciting research, development and business opportunities. Such scenarios clearly demand significant upgrades to the existing communication paradigm in terms of infrastructure, devices and services to support the “anytime, anywhere, any device” philosophy, providing novel and fast-evolving requirements and expectations on - search and development in the field of information and communication technologies. The core issue is to support wireless users' desire for 24/7 network availability and transparent access to "their own" services. In this context, we continue to envision an international forum where practitioners and researchers coming from the many areas involved in lightweight wireless systems’ design and deployment would be able to interact and exchange experiences.

Download or read book Quality Reliability Security and Robustness in Heterogeneous Networks written by Xi Zhang and published by Springer. This book was released on 2012-04-23 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the thoroughly refereed post-conference proceedings of the 7th International Conference on Heterogeneous Networking for Quality, Reliability, Security and Robustness, QShine 2010. The 37 revised full papers presented along with 7 papers from the allocated Dedicated Short Range Communications Workshop, DSRC 2010, were carefully selected from numerous submissions. Conference papers are organized into 9 technical sessions, covering the topics of cognitive radio networks, security, resource allocation, wireless protocols and algorithms, advanced networking systems, sensor networks, scheduling and optimization, routing protocols, multimedia and stream processing. Workshop papers are organized into two sessions: DSRC networks and DSRC security.

Download or read book Energy Efficiency written by Moustafa Eissa and published by BoD – Books on Demand. This book was released on 2012-10-17 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is one of the most comprehensive and up-to-date books written on Energy Efficiency. The readers will learn about different technologies for energy efficiency policies and programs to reduce the amount of energy. The book provides some studies and specific sets of policies and programs that are implemented in order to maximize the potential for energy efficiency improvement. It contains unique insights from scientists with academic and industrial expertise in the field of energy efficiency collected in this multi-disciplinary forum.

Download or read book An Information Theoretic Framework for Two way Relay Networks written by Jonathan Ponniah and published by . This book was released on 2008 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: We propose an information theoretic framework for scheduling the transmissions in a two-way multi-hop network. First we investigate some long standing open problems that were encountered during the course of the research. To illustrate their difficulty, we describe some failed attempts at resolving them. We then introduce the two-way one-relay channel. It turns out that the achievable rate region of this network has a nice interpretation, especially when viewed in the context of the open problems examined earlier. Motivated by this observation, we attempt to extend this achievable region to the two-way two-relay channel. In the process, we expose a fundamental deadlock problem in which each relay needs to decode before the other in order to enable mutual assistance. Our most important contribution is a resolution to this deadlock problem; we add an additional constraint that ensures some relay can decode at least one message before the other relay. Furthermore, we also introduce several coding schemes to prove that the additional constraint is indeed sufficient. Our schemes also show that information theory provides unique insight into scheduling the transmissions of multi-hop networks.

Download or read book Performance Analysis of Amplify and Forward Wireless Relay Networks written by Muhammad Khalil and published by . This book was released on 2017 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless relay technology plays an important role in the next-generation mobile and wireless networks. It has been proposed as a cost effective solution to addressing a growing demand for high data rates and low power consumption. In the relay communication model, a source communicates to a destination through a wireless node(s) called a relay. There are two main relaying techniques: Decode-and-Forward (DF) and Amplify-and-Forward (AF). AF is the focus of this thesis. The AF relay networks provide considerable performance improvement in link reliability, Spectral Efficiency (SE), Energy Efficiency (EE) and Bit Error Rate (BER) performance. They also offer a low-complexity solution for practical relay networks that have critical energy constraints, as they enable the received signal to be amplified without the decoding process at the relays. This thesis proposes new methods of reducing the energy consumption and evaluating the error performance of AF relay networks, when the relay is either one-way (unidirectional) or two-way (bidirectional). The analysis is commenced by formulating the actual Signals-to-Noise Ratio (SNR) level, which corresponds to a low SNR level, in order to calculate the Exact Bit Error Rate (EBER) performance. Then, the approximated SNR, which refers to a high SNR level, is expressed and adopted to evaluate the Asymptotic Bit Error Rate (ABER). Another SNR level is presented in this work and defined as an optimal SNR level, which is obtained by optimal balancing of the SE and EE. The optimal SNR level allows evaluation of the ABER and the EBER of AF relay networks under optimal SNR conditions. Accordingly, a unifying BER evaluation at low, high, and optimal levels of AF relay networks is provided in this study. This thesis focuses on a high SNR level to derive an effective method for evaluating the ABER and EBER, whether in optimal or sub-optimal AF relay networks. The effectiveness of such a BER evaluation method is demonstrated by enhancing the ABER of AF relay networks at all SNR levels (i.e., low, high, optimal SNR levels). This is shown when disparity between the ABER and the EBER at a low SNR level is reduced, and this helps to calculate the accurate BER of AF relay networks under any SNR levels using either the ABER or EBER. The proposed methods are examined under different channels environments, as in practice the channel of each hop of an AF relay network can be located in a different environment. When both hops are located in the same environment, the fading channels of the hops are equal, while for different environments, the fading channels of the hops are different. Furthermore, relay location is also investigated for the aforementioned ABER and EBER, and a new method for determining the relationship between the EE and EBER with relay location is derived.

Download or read book Amplify and Forward Relaying in Wireless Communications written by Leonardo Jiménez Rodríguez and published by Springer. This book was released on 2015-05-22 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: This SpringerBrief explores the advantage of relaying techniques in addressing the increasing demand for high data rates and reliable services over the air. It demonstrates how to design cost-effective relay systems that provide high spectral efficiency and fully exploit the diversity of the relay channel. The brief covers advances in achievable rates, power allocation schemes, and error performance for half-duplex (HD) and full-duplex (FD) amplify-and-forward (AF) single-relay systems. The authors discuss the capacity and respective optimal power allocation for a wide range of HD protocols over static and fading channels. Then, optimal amplification coefficients in terms of achievable rate are presented. Chapters also examine performance with finite constellations, including the error and diversity performance. The brief concludes with a capacity and error performance analysis of the FD relay mode of operation, where the residual self-interference due to FD transmission is explicitly taken into account. Amplify-and-Forward Relaying in Wireless Communications reveals the benefits and challenges of relaying techniques. It is designed for researchers and professionals in wireless communication. This material is also appropriate for advanced-level students in electrical engineering and computer science.