Download or read book Cross layer Throughput Optimization of Wireless Networks written by Eyidayo Friday Adebola and published by . This book was released on 2012 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Resource Allocation and Cross layer Control in Wireless Networks written by Leonidas Georgiadis and published by Now Publishers Inc. This book was released on 2006 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Transmission Scheduling Based on a New Conflict Graph Model for Multicast in Multihop Wireless Networks written by Quanmin Ye and published by . This book was released on 2014 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Wireless networks are undergoing rapid progress and inspiring numerous applications. As the application of wireless networks becomes broader, they are expected to not only provide ubiquitous connectivity, but also support end users with certain service guarantees. End-to-end delay is an important Quality of Service (QoS) metric in multihop wireless networks. This dissertation addresses how to minimize end-to-end delay through joint optimization of network layer routing and link layer scheduling. Two cross-layer schemes, a loosely coupled cross-layer scheme and a tightly coupled cross-layer scheme, are proposed. The two cross-layer schemes involve interference modeling in multihop wireless networks with omnidirectional antenna. In addition, based on the interference model, multicast schedules are optimized to minimize the total end-to-end delay. Throughput is another important QoS metric in wireless networks. This dissertation addresses how to leverage the spatial multiplexing function of MIMO links to improve wireless network throughput. Wireless interference modeling of a half-duplex MIMO node is presented. Based on the interference model, routing, spatial multiplexing, and scheduling are jointly considered in one optimization model. The throughput optimization problem is first addressed in constant bit rate networks and then in variable bit rate networks. In a variable data rate network, transmitters can use adaptive coding and modulation schemes to change their data rates so that the data rates are supported by the Signal to Noise and Interference Ratio (SINR). The problem of achieving maximum throughput in a millimeter-wave wireless personal area network is studied"--Abstract, page iv.

Download or read book Cross layer Design for Network Performance Optimization in Wireless Networks written by Xuan Gong and published by . This book was released on 2011 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In this dissertation, I use mathematical optimization approach to solve the complex network problems. Paper l and paper 2 first show that ignoring the bandwidth constraint can lead to infeasible routing solutions. A sufficient condition on link bandwidth is proposed that makes a routing solution feasible, and then a mathematical optimization model based on this sufficient condition is provided. Simulation results show that joint optimization models can provide more feasible routing solutions and provide significant improvement on throughput and lifetime. In paper 3 and paper 4, an interference model is proposed and a transmission scheduling scheme is presented to minimize the end-to-end delay. This scheduling scheme is designed based on integer linear programming and involves interference modeling. Using this schedule, there are no conflicting transmissions at any time. Through simulation, it shows that the proposed link scheduling scheme can significantly reduce end-to-end latency. Since to compute the maximum throughput is an NP-hard problem, efficient heuristics are presented in Paper 5 that use sufficient conditions instead of the computationally-expensive-to-get optimal condition to capture the mutual conflict relation in a collision domain. Both one-way transmission and two-way transmission are considered. Simulation results show that the proposed algorithms improve network throughput and reduce energy consumption, with significant improvement over previous work on both aspects. Paper 6 studies the complicated tradeoff relation among multiple factors that affect the sensor network lifetime and proposes an adaptive multi-hop clustering algorithm. It realizes the best tradeoff among multiple factors and outperforms others that do not. It is adaptive in the sense the clustering topology changes over time in order to have the maximum lifetime"--Abstract, leaf iv.

Download or read book Wireless Ad Hoc and Sensor Networks written by Raja Jurdak and published by Springer Science & Business Media. This book was released on 2007-04-27 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the optimization potential of cross-layer design approaches for wireless ad hoc and sensor network performance, covering both theory and practice. A theoretical section provides an overview of design issues in both strictly layered and cross-layer approaches. A practical section builds on these issues to explore three case studies of diverse ad hoc and sensor network applications and communication technologies.

Download or read book Throughput Optimization in Multi hop Wireless Networks with Random Access written by Md. Forkan Uddin and published by . This book was released on 2011 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research investigates cross-layer design in multi-hop wireless networks with random access. Due to the complexity of the problem, we study cross-layer design with a simple slotted ALOHA medium access control (MAC) protocol without considering any network dynamics.

Download or read book Fundamental Performance Limits in Cross Layer Wireless Optimization written by Edmund M. Yeh and published by Now Pub. This book was released on 2012-12 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental Performance Limits in Cross-layer Wireless Optimization reviews some key problem settings and results where the cross-layer design paradigm has significantly influenced our understanding of communication systems in recent years.

Download or read book Cross Layer Optimizations for Performance Enhancement in Wireless Networks written by and published by . This book was released on 2008 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we focus on optimizing link layer performance and maximizing throughput in IEEE 802.11 wireless networks. We categorize our efforts into two directions: (a) throughput optimization and analysis of the 802.11 multi-rate networks via rate adaptation (b) design of a new MAC protocol for emerging multipacket reception capable wireless networks. Both our proposals assume cross layer interaction between the MAC and the PHY layers. In the first part of the work, we focus on the use of rate adaptation for throughput gains in time-varying wireless channels. We thoroughly investigate the impact of transmission rate on the performance of a wireless link. We then propose Stochastic Automata Rate Adaptation Algorithm (SARA) inspired by Stochastic Learning Automata (SLA), a machine learning technique for adaptation in random environments. Besides boosting throughput, SARA also provides an integrated and distributed solution for both stationary and non-stationary channel environments. SARA is completely compatible with existing IEEE 802.11 MAC standards. In the second part of the work, we move on to more advanced 802.11 networks that employ techniques like multiple antennas, DS-CDMA codes, spatial diversity techniques etc and have the capability of receiving multiple packets simultaneously. To provide the maximum performance benefits in these networks, we propose the use of a new MAC protocol Receiver-Based Multipacket Reception MAC (RB-MPR MAC) that relies on the use of a Multipacket Reception (MPR) matrix as cross-layer information. The application of MPR matrix, its benefits and limitations, impact of partitioning the network (Grouping) in a DS-CDMA system have been analyzed thoroughly and important results and interpretations have been put forward.

Download or read book Wireless Networks Multiuser Detection in Cross Layer Design written by Christina Comaniciu and published by Springer Science & Business Media. This book was released on 2006-06-14 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Cross Layer Techniques to Enhance Link Performance in Wireless Networks written by Damanjit Singh and published by . This book was released on 2007 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we improve the link performance by employing cross-layer techniques in two totally different wireless environments: a) IEEE 802.11 wireless networks and b) ultra-wideband wireless ad hoc networks. The cross-layer information exchange between the MAC and the PHY layer is used to maximize the link throughput. In the first part, we achieve the throughput gain by solving the problem of rate adaptation in IEEE 802.11 networks using the proposed Stochastic Automata Rate Adaptation (SARA) algorithm. SARA is inspired from Stochastic Learning Automata (SLA), a machine learning technique for adaptation in random environments and is fully compatible with IEEE 802.11 MAC. Next, we focus on improving the link performance in ultra-wideband wireless networks by exposing the MAC layer to the presence of multiple orthogonal pulse shapes at the physical layer. These pulse shapes have been recently proposed for ultra-wideband systems and have been used to improve the system performance at the physical layer. However, at the MAC layer, very few designs based on utilizing these pulse shapes have been proposed. In this thesis, we first propose an alternative way to use these pulse shapes at the physical layer to achieve high data rates. Next, we show that these pulse shapes can increase both the rate and the reliability of packet transmission at the MAC layer. To achieve better reliability, we introduce and develop the idea of 'pulse shape redundancy'. Two throughput optimization techniques based on these ideas and findings are then analytically developed. After this, we propose a new MAC protocol, namely Redundancy-Enabled MAC (REMAC), which is capable of employing either of the two proposed schemes. Finally, we illustrate the performance gain achieved by REMAC and the role of redundancy through extensive simulation results and discussions.

Download or read book Channel Aware Scheduling and Resource Allocation with Cross Layer Optimization in Wireless Networks written by Sheu-Sheu Tan and published by . This book was released on 2013 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: We develop channel aware scheduling and resource allocation schemes with cross-layer optimization for several problems in multiuser wireless networks. We consider problems of distributed opportunistic scheduling, where multiple users contend to access the same set of channels. Instead of scheduling users to the earliest available idle channels, we also take the instantaneous channel quality into consideration and schedule the users only when the channel quality is sufficiently high. This can lead to significant gains in throughput compared to system where PHY and MAC layers are designed separately and the wireless fading channels are abstracted as time invariant, fixed rate channels for scheduling purposes. We first consider opportunistic spectrum access in a cognitive radio network, where a secondary user (SU) share the spectrum opportunistically with incumbent primary users (PUs). Similar to earlier works on distributed opportunistic scheduling (DOS), we maximize the throughput of SU by formulating the channel access problem as a maximum rate-of-return problem in the optimal stopping theory framework. We show that the optimal channel access strategy is a pure threshold policy, namely the SU decides to use or skip transmission opportunities by comparing the channel qualities to a fixed threshold. We further increase the spectrum utilization by interleaving SU's packets with periodic sensing to detect PU's return. We jointly optimize the rate threshold and the packet transmission time to maximize the average throughput of SU, while limiting interference to PU. Next, we develop channel-aware opportunistic spectrum access strategies in a more general cognitive radio network with multiple SUs. Here, we additionally take into account the collisions and complex interaction between SUs and sharing of resources between them. We derive strategies for both cooperative settings where SUs maximize their sum total of throughputs, as well as non-cooperative game theoretic settings, where each SU tries to maximize its own throughput. We show that the optimal schemes for both scenarios are pure threshold policies. In the non-cooperative case, we establish the existence of Nash equilibrium and develop best response strategies that can converge to equilibria, with SUs relying only on their local observations. We study the trade-off between maximal throughput in the cooperative setting and fairness in the non-cooperative setting, and schemes based on utility functions and pricing that mitigate this tradeoff. In addition to maximizing throughput and fair sharing of resources, it is important to consider network/scheduling delays for QoS performance of delay-sensitive applications. We study DOS under both network-wide and user-specific average delay constraints. We take a stochastic Lagrangian approach and characterize the corresponding optimal scheduling policies accordingly, and show that they have a pure threshold structure. Next, we consider the use of different types of channel quality information, i.e., channel state information (CSI) and channel distribution information (CDI) in the opportunistic scheduling design for MIMO ad hoc networks. CSI is highly dynamic in nature and provides time diversity in the wireless channel, but is difficult to track. CDI offers temporal stability, but is incapable of capturing the instantaneous channel conditions. We design a new class of cross-layer opportunistic channel access scheduling framework for MIMO networks where CDI is used in the network context to group the simultaneous transmission links for spatial channel access and CSI is used in the link context to decide when and which link group should transmit based on a pre designed threshold. We thereby reap the benefits of both the temporal stability of CDI and the time diversity of CSI. Finally, we consider a novel application of cross layer optimization for communication of progressive coded images over OFDM wireless fading channels. We first consider adaptive modulation based on the instantaneous channel state information. An algorithm is proposed to allocate power and constellation size at each subchannel by maximizing the throughput. We next consider both the variance and the average of the throughput when deciding the constellation size for adaptive modulation. Simulation results confirm that cross-layer optimization with adaptive modulation enhances system performance.

Download or read book Cross layer Optimization in Wireless Multihop Networks written by Samat Shabdanov and published by . This book was released on 2012 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to meet the increasing demand for higher data rates, next generation wireless networks must incorporate additional functionalities to enhance network throughput. Multihop networks are considered as a promising alternative due to their ability to exploit spatial reuse and to extend coverage. Recently, industry has shown increased interest in multihop networks as they do not require additional infrastructure and have relatively low deployment costs. Many advances in physical and network layer techniques have been proposed in the recent past and they have been studied mostly in single-hop networks. Very few studies, if any, have tried to quantify the gains that these techniques could provide in multihop networks. We investigate the impact of simple network coding, advanced physical layer and cooperative techniques on the maximum achievable throughput of wireless multihop networks of practical size. We consider the following advanced physical layer techniques: successive interference cancellation, superposition coding, dirty-paper coding, and some of their combinations. We achieve this by formulating several cross-layer frameworks when these techniques are jointly optimized with routing and scheduling. We also formulate power allocation subproblems for the cases of continuous power control and superposition coding. We also provide numerous engineering insights by solving these problems to optimality.

Download or read book Cross Layer Optimization for Protocols in Mobile Adhoc Networks written by Anita Yadav and published by GRIN Verlag. This book was released on 2020-03-17 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Doctoral Thesis / Dissertation from the year 2016 in the subject Computer Science - Miscellaneous, grade: 16, , language: English, abstract: In this thesis, we have modified AODV routing protocol by incorporating link prediction algorithm using a proposed link prediction model. This algorithm predicts the link availability time and even before the link breaks; either it repairs the route locally or sends information to the source nodes to enable them to initiate a new route search well in time. This algorithm improves the quality of service of the network. Simulation results show that AODV routing algorithm with link availability model performs better than the existing AODV. Advances in wireless technology and hand-held computing devices have brought revolution in the area of mobile communication. The increasing mobility of humans across the globe generated demand for infrastructure-less and quickly deployable mobile networks. Such networks are referred to as Mobile Adhoc Networks (MANET). Usually, nodes in a MANET also act as a router while being is free to roam while communicating each others. Adhoc networks are suited for use in situations where infrastructure is unavailable or to deploy one is not cost-effective. Frequent changes in network topology due to mobility and limited battery power of the mobile devices are the key challenges in the adhoc networks. The depletion of power source may cause early unavailability of nodes and thus links in the network. The mobility of nodes will also causes frequent routes breaks and adversely affects the required performance for the applications. Availability of a route in future mainly depends on the availability of links between the nodes forming the route. Therefore, it is important to predict the future availability of a link that is currently available. We have proposed an analytical model for link prediction using Newton divided difference method. This link availability algorithm is incorporated in AODV routing algorithm (AODVLP) to evaluate the performance of AODV routing protocol using the metrics viz. delivery rate, average end-to-end delay, average RTS collisions per node and route failure. In the existing AODV protocol, packets are routed until a link in the existing path fails. This results in degradation of quality of service of network in terms of end-to-end delay and delivery ratio.

Download or read book Cross Layer Resource Allocation in Wireless Communications written by Ana I. Perez-Neira and published by Academic Press. This book was released on 2010-07-28 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cross-Layer Resource Allocation in Wireless Communications offers practical techniques and models for the design and optimisation of cross-layer resource allocation – one of the hottest topics in wireless communications. Resource allocation in wireless networks is traditionally approached either through information theory or communications networks. To break down the barriers between these distinct approaches, this book bridges the physical and network layers by providing cross-layer resource allocation techniques, models, and methodologies. Its unique approach allows optimisation of network resources and will enable engineers to improve signal quality, enhance network and spectrum utilization, increase throughput, and solve the problem of shadowing. Topics covered include different views of spectral efficiency, the role of spatial diversity, of delay in resource allocation, and possible extensions to OFDMA systems. This will be an ideal reference on cross-layer resource allocation between the PHY and MAC layers for R&D and network design engineers and researchers in universities dealing with sensor networks and cognitive systems. Gives a full description of the characteristics of the PHY layer that promote efficient resource allocation strategies Gives special emphasis on cross-layer design for spatial diversity schemes Provides a framework for interaction between the PHY and MAC layers, their parameters of performance and their relationship Presents resource allocation as a cross-layer design based on an optimization of MAC layer parameters with an accurate model of the PHY layer

Download or read book Cross Layer Optimization of Complex Wireless Environments written by Stephen B. Gwanvoma and published by . This book was released on 2014 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Using Cross Layer Techniques for Communication Systems written by Rashvand, Habib F. and published by IGI Global. This book was released on 2012-04-30 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Future Wireless and Optical Networks written by Shengming Jiang and published by Springer Science & Business Media. This book was released on 2012-02-22 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the challenges of all-optical and wireless networks for the future Internet, with a focus on cross-layer design and optimization. Features: presents a thorough introduction to major networking modes and their effect on Internet development; proposes a new structure favorable for all-optical packet switching; discusses a new quality of service (QoS) provisioning approach, which overcomes the scalability problem of IntServ and the coarse QoS granularity of DiffServ; describes the end-to-end arguments in Internet design, before investigating a solution to congestion control problems in multi-hop wireless and all-optical networks; examines how to exploit multiple-input-multiple-output technology to improve network performance in centralized wireless networks; surveys green networking strategies from a quantitative perspective; suggests a strategic vision for possible developments of network technology for the future Internet.