Author: Xuefu Zhou
Publisher:
ISBN:
Category :
Languages : en
Pages : 132
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An underlying assumption of the traditional layered protocol architecture is that all layers can be optimized independently. Unfortunately, this assumption is not satisfied in wireless networks because wireless links introduce interdependence between PHY and upper layers. This dissertation investigates the impact of channel conditions on the performance of IEEE 802.11 DCF and proposes cross-layer optimization and design approach to improve the performance of DCF in fade channels. First, novel fade-induced packet error rate expressions based on fading statistics and error correction capability are developed. Based on these results, we propose a cross-layer analytical model to analyze the performance of IEEE 802.11 DCF in fading channels. The impact of channel conditions on the DCF performance is revealed. Second, a viable cross-layer optimization and design approach to improve the performance of DCF in fading channels is proposed. By employing the practically measurable PHY information, the DCF can adapt its packet length to maximize the throughput. By deploying multiple antennas at PHY for the purpose of spatial diversity, fading-induced packet error rate is reduced and the DCF performance in fading channels is significantly improved. Ironically, in wireless networks, channel fading and path loss may degrade the signal quality at the receiver and cause fade-induced packet errors; however, they also result in capture effect phenomena to make it possible for some packets to be received successfully in the presence of collision. Well-known capture probability expressions exist for Rayleigh fading channels, i.e., non-line-of-sight environments. However, WLANs using DCF are supposed to be deployed in micro-cellular and pico-cellular environments where Ricean fading channels are more likely to exist. Therefore, we develop a new analytical expression for the capture probability for WLANs using DCF in Ricean fading channels. Furthermore, by incorporating the capture probability expression, we evaluate the DCF performance in fading channels with capture effect. Results show that, with capture effect, the performance of DCF in fading channels is better than that under ideal channel conditions without capture effect.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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This thesis studies several research problems in the area of wireless local area networks (WLANs) with an objective of improving network efficiency, quality-of-service and user satisfactions. The I E E E 802.11 Working Group has been under rapid development and expansion in recent years following the successful deployment of the 802.11 network around the globe. The thesis work has been striving to study several key problems in these developments and propose effective schemes to improve network performance. The original 802.11 standard presents a simple and robust design, but has relatively low data rate and lacks QoS support. The recent 802.11e standard and the 8 0 2 . l ln proposals aim to significantly improve the network performance in terms of QoS and throughput. In this thesis, an analytical model of I E E E 802.11e WLANs is first presented. With the help of this throughput model, an admission control scheme for a multi-hop 802.11e W L A N is proposed. To fully utilize the high data rate provided by 802.11n, the performance improvement of the M A C protocol by frame aggregation is studied. Two frame aggregation techniques, namely A - M P D U (MAC Protocol Data Unit Aggregation) and A - M S D U (MAC Service Data Unit Aggregation) are considered. Furthermore, a comprehensive network setup is studied where the QoS requirements of the 802.11e M A C and the MIMO physical layer of 8 0 2 . l ln are both considered. Cross-layer design schemes are proposed for WLANs under two different M A C protocols: the carrier sense multiple access with collision avoidance (CSMA/CA)-based 802.11e M A C, and the slotted Aloha M A C . Lastly, the thesis studies the problem of cooperative transmission in a wireless ad-hoc network with extensions to the 802.11 M A C protocols. A complete system framework is proposed for wireless adhoc networks utilizing two different cooperative relaying techniques at the physical layer: the repetition coding and the space-time coding. In the data link.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 52
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Book Description
We have shown certain invariants (optimum distance, optimum error probability); by considering a couple layers joint design/optimization and analysis is possible; insight into performance analysis can be obtained; still need to consider many other factors (power control, data rate control, multiple access capability of modulation and coding); there are many open and interesting problems in cross-layer design.
Author: Leonhard Korowajczuk
Publisher: John Wiley & Sons
ISBN: 047074149X
Category : Technology & Engineering
Languages : en
Pages : 784
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Book Description
A technological overview of LTE and WiMAX LTE, WiMAX and WLAN Network Design, Optimization and Performance Analysis provides a practical guide to LTE and WiMAX technologies introducing various tools and concepts used within. In addition, topics such as traffic modelling of IP-centric networks, RF propagation, fading, mobility, and indoor coverage are explored; new techniques which increase throughput such as MIMO and AAS technology are highlighted; and simulation, network design and performance analysis are also examined. Finally, in the latter part of the book Korowajczuk gives a step-by-step guide to network design, providing readers with the capability to build reliable and robust data networks. By focusing on LTE and WiMAX this book extends current network planning approaches to next generation wireless systems based on OFDMA, providing an essential resource for engineers and operators of fixed and wireless broadband data access networks. With information presented in a sequential format, LTE, WiMAX and WLAN Network Design, Optimization and Performance Analysis aids a progressive development of knowledge, complementing latter graduate and postgraduate courses while also providing a valuable resource to network designers, equipment vendors, reference material, operators, consultants, and regulators. Key Features: One of the first books to comprehensively explain and evaluate LTE Provides an unique explanation of the basic concepts involved in wireless broadband technologies and their applications in LTE, WiMAX, and WLAN before progressing to the network design Demonstrates the application of network planning for LTE and WiMAX with theoretical and practical approaches Includes all aspects of system design and optimization, such as dynamic traffic simulations, multi-layered traffic analysis, statistical interference analysis, and performance estimations
Author: Imam Mahmud Taifur Rahman AL-Wazedi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Christina Comaniciu
Publisher: Springer Science & Business Media
ISBN: 0387277501
Category : Technology & Engineering
Languages : en
Pages : 214
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Book Description
Cross-layer design seeks to enhance the capacity of wireless networks significantly through the joint optimization of multiple layers in the network, primarily the physical (PHY) and medium access control (MAC) layers. Although there are advantages of such design in wireline networks as well, this approach is particularly advantageous for wireless networks due to the properties (such as mobility and interference) that strongly affect performance and design of higher layer protocols. This unique monograph is concerned with the issue of cross-layer design in wireless networks, and more particularly with the impact of node-level multiuser detection on such design. It provides an introduction to this vibrant and active research area insufficiently covered in existing literature, presenting some of the principal methods developed and results obtained to date. Accompanied by numerous illustrations, the text is an excellent reference for engineers, researchers and students working in communication networks.
Author: Rashvand, Habib F.
Publisher: IGI Global
ISBN: 1466609613
Category : Computers
Languages : en
Pages : 656
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Book Description
Although the existing layering infrastructure--used globally for designing computers, data networks, and intelligent distributed systems and which connects various local and global communication services--is conceptually correct and pedagogically elegant, it is now well over 30 years old has started create a serious bottleneck. Using Cross-Layer Techniques for Communication Systems: Techniques and Applications explores how cross-layer methods provide ways to escape from the current communications model and overcome the challenges imposed by restrictive boundaries between layers. Written exclusively by well-established researchers, experts, and professional engineers, the book will present basic concepts, address different approaches for solving the cross-layer problem, investigate recent developments in cross-layer problems and solutions, and present the latest applications of the cross-layer in a variety of systems and networks.
Author: Nizar Zorba
Publisher: Troubador Publishing
ISBN: 9781848768109
Category : Computers
Languages : en
Pages : 307
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Book Description
This book aims to serve as a comprehensive technical guide and reference material for practitioners, engineers, scientists and researchers providing them with the state-of-the-art of research work and recent achievements in different aspects of cross-layer for WLAN systems. Wireless Local Area Networks (WLAN) have turned into a very attractive solution to offer network connectivity, providing user mobility, flexibility and easy deployment at a relatively low cost. The popularity and the traffic load of WLANs grows as well as the necessity to support real-time delay-sensitive applications such as voice, video streaming or online gaming. Therefore, the need for higher efficiency and Quality of Service (QoS) guarantees becomes necessary. It has been proved that the consideration of the physical layer transmission characteristics from the higher layers can significantly improve the efficiency of WLAN systems. In general, the exchange of information between different layers of the OSI model is known as 'Cross-Layer' design, and is a very promising field of investigation and deployment. The objective of this book is to serve as a comprehensive technical guide and reference material for practitioners, engineers, scientists and researchers providing them with the state-of-the-art of research work and recent achievements in different aspects of cross-layer for WLAN systems. Volume 2 of a 2 volume series Volume 2 ISBN 9781848762275
Author: Stephen B. Gwanvoma
Publisher:
ISBN:
Category : Cross-layer designs (Telecommunications)
Languages : en
Pages : 142
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Book Description
Cross-layer design and optimization is a new technique which can be used to design and improve the performance in both wireless and wireline networks. The central idea of cross-layer design is to optimize the control and exchange of information over two or more layers to achieve significant performance improvements by exploiting the interaction between various protocol layers. Designing for wireless networks such as cellular networks, WLANs, mobile ad hoc networks (MANETs) and Wireless Sensor Networks (WSNs), poses more stringent requirements than wireline networks and are considerably different in their applications and architectures, although all use wireless channel for communication. Promising results achieved by cross-layer optimizations initiated significant research activity in this area. Due to features such as ease of deployment, increased coverage and enhanced capacity, multi hop wireless networks like ad hoc networks, and mixed network that form the network in a self-organized manner without relying on fixed infrastructure is touted as the new frontier of wireless networking. This work aims to review the present study on the cross-layer paradigm for QoS support in multi-hop wireless networks. Several examples of evolutionary and revolutionary cross-layer approaches are presented in detail. The Cross-Talk architecture represents one of the more aggressive approaches to cross layer improvement. This architecture enables performance related decisions at the global level that can propagate down to the local layer. This architecture fits the Mixed Network modeling developed here at MSU for the iNET project. Organizing the Mixed Networks solutions into the framework of the Cross-Talk Architecture will allow this work to build on the body of research already in place for cross layering.-- Abstract.
Author: Leonidas Georgiadis
Publisher: Now Publishers Inc
ISBN: 1933019263
Category : Technology & Engineering
Languages : en
Pages : 161
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Book Description
Information flow in a telecommunication network is accomplished through the interaction of mechanisms at various design layers with the end goal of supporting the information exchange needs of the applications. In wireless networks in particular, the different layers interact in a nontrivial manner in order to support information transfer. In this text we will present abstract models that capture the cross-layer interaction from the physical to transport layer in wireless network architectures including cellular, ad-hoc and sensor networks as well as hybrid wireless-wireline. The model allows for arbitrary network topologies as well as traffic forwarding modes, including datagrams and virtual circuits. Furthermore the time varying nature of a wireless network, due either to fading channels or to changing connectivity due to mobility, is adequately captured in our model to allow for state dependent network control policies. Quantitative performance measures that capture the quality of service requirements in these systems depending on the supported applications are discussed, including throughput maximization, energy consumption minimization, rate utility function maximization as well as general performance functionals. Cross-layer control algorithms with optimal or suboptimal performance with respect to the above measures are presented and analyzed. A detailed exposition of the related analysis and design techniques is provided.
