Download or read book Modeling and Optimization of Wireless Local Area Networks MAC Protocols written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As wireless local area network (WLAN) technology is gaining popularity, performance analysis and optimization of it becomes more important. However, as compared to wired LAN, wireless channels are error-prone. Most of the existing work on the performance analysis of IEEE 802.11 distributed coordination function (DCF) assumes saturated traffic and ideal channel condition. In this dissertation, DCF is analyzed under a general traffic load and variable channel condition. A more realistic and comprehensive model is proposed to optimize the performance of DCF in both ideal and error-prone channels. Many factors, such as the number of contending nodes, the traffic load, contention window, packet overhead and channel condition, which affect the performance of a wireless network have been incorporated. It is shown that under error-prone environment, a trade-off exists between the desire to reduce the ratio of overhead in the data packet by adopting a larger packet size, and the need to reduce the packet error rate by using a smaller packet length. Based on our analytical model, both the optimal packet size and the optimal minimum contention window are determined under various traffic loads and channel conditions. It is also observed that, in error-prone environments, optimal packet size has more significant improvement on the performance than optimal contention window. Our analytical model is validated via simulations using ns-2. We provide a novel approach to model the different channel conditions incurred by different nodes. This work has applications in performance optimization by establishing tradeoffs between transmission error rate and transmission power, modulation, coding scheme, packet size. A better approach of modeling the wireless channel is considered. A Markov chain with alternating good and bad states is adopted to model the bursty characteristics of wireless channel errors. Furthermore, we introduce an analytical model to investigate the energy efficiency of 802.11 DCF. Our future work will extend existing work to further performance enhancement for 802.11 DCF. Also we plan to apply our work in 802.11 to UWB (Ultra-wideband) since CSMA/CA is defined for UMB MAC protocol. To solve the new research challenge of UWB, we will consider a new channel model and channel estimation approach.

Download or read book Cross layer Optimization in Wireless Local Area Networks written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book MAC Protocol Design in Full Duplex Enabled Wireless Networks written by Liqun Fu and published by Springer Nature. This book was released on with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Simulation Modeling and Analysis of Wireless Local Area Networks Supporting the IEEE 802 11 Standard written by Jaikwan Joo and published by . This book was released on 1998-12-01 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research to improve the performance of the IEEE 802.11 has been ongoing since 1990. The focus of this research has investigated the use of the MAC and Physical layers for improving throughput. An adaptive MAC protocol, CATER (Code Adapts To Enhance Reliability) is based on the proposed MAC standard for wireless local area networks (WLAN)-802. 11. IEEE 802.11 uses a fixed Pseudo-Noise (PN) code for spreading the information signal, implying a fixed process gain at the receiver. When the channel degrades, IEEE 802.11 offers only retransmissions at the MAC layer to contend with the corrupted medium. However, CATER allows communicating stations to reconfigure their transceivers to use a longer PN code after a prescribed number of failed retransmissions. The longer PN code increases the process gain of the receiver and reduces the error rate. This thesis analyzes the performance of CATER as changing the factor: Start (the number of transmission before the channel is reconfigured) and Max (additional frame transmissions during reconfigure), PN code length, the number of station, and implementing Forward Error Correction (FEC). CATER provides better throughput for smaller Start and larger Max at a high bit error rate (10-3). When CATER uses a PN code length of 63, the throughput is increased by 101 percent at high bit error rate (BER). However, 802.11 is better than CATER at low BER ( 10-3).

Download or read book Improving the Performance of Wireless LANs written by Nurul Sarkar and published by CRC Press. This book was released on 2014-01-08 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: While there are countless books on wireless networks, few actually quantify the key performance-limiting factors of wireless local area networks (WLANs) and describe various methods for improving WLAN performance. Fulfilling these needs, Improving the Performance of Wireless LANs: A Practical Guide provides both theoretical background and empirical

Download or read book Handbook of Wireless Local Area Networks written by Mohammad Ilyas and published by CRC Press. This book was released on 2005-05-25 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Wireless Local Area Networks: Applications, Technology, Security, and Standards captures the current state of wireless LANs, and serves as the single comprehensive reference on the subject. Addressing challenges related to the further development of WLAN technology, the Handbook covers the entire spectrum of topics from basic concepts t

Download or read book Mobile Ad Hoc Networking written by Stefano Basagni and published by John Wiley & Sons. This book was released on 2013-02-07 with total page 690 pages. Available in PDF, EPUB and Kindle. Book excerpt: "An excellent book for those who are interested in learning the current status of research and development . . . [and] who want to get a comprehensive overview of the current state-of-the-art." —E-Streams This book provides up-to-date information on research and development in the rapidly growing area of networks based on the multihop ad hoc networking paradigm. It reviews all classes of networks that have successfully adopted this paradigm, pointing out how they penetrated the mass market and sparked breakthrough research. Covering both physical issues and applications, Mobile Ad Hoc Networking: Cutting Edge Directions offers useful tools for professionals and researchers in diverse areas wishing to learn about the latest trends in sensor, actuator, and robot networking, mesh networks, delay tolerant and opportunistic networking, and vehicular networks. Chapter coverage includes: Multihop ad hoc networking Enabling technologies and standards for mobile multihop wireless networking Resource optimization in multiradio multichannel wireless mesh networks QoS in mesh networks Routing and data dissemination in opportunistic networks Task farming in crowd computing Mobility models, topology, and simulations in VANET MAC protocols for VANET Wireless sensor networks with energy harvesting nodes Robot-assisted wireless sensor networks: recent applications and future challenges Advances in underwater acoustic networking Security in wireless ad hoc networks Mobile Ad Hoc Networking will appeal to researchers, developers, and students interested in computer science, electrical engineering, and telecommunications.

Download or read book Position Location Techniques and Applications written by David Munoz and published by Academic Press. This book was released on 2009-05-15 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the definitive guide to the techniques and applications of position location, covering both terrestrial and satellite systems. It gives all the techniques, theoretical models, and algorithms that engineers need to improve their current location schemes and to develop future location algorithms and systems. Comprehensive coverage is given to system design trade-offs, complexity issues, and the design of efficient positioning algorithms to enable the creation of high-performance location positioning systems. Traditional methods are also reexamined in the context of the challenges posed by reconfigurable and multihop networks. Applications discussed include wireless networks (WiFi, ZigBee, UMTS, and DVB networks), cognitive radio, sensor networks and multihop networks. Features Contains a complete guide to models, techniques, and applications of position location Includes applications to wireless networks, demonstrating the relevance of location positioning to these "hot" areas in research and development Covers system design trade-offs and the design of efficient positioning algorithms, enabling the creation of future location positioning systems Provides a theoretical underpinning for understanding current position location algorithms, giving researchers a foundation to develop future algorithms David Muñoz is Director and César Vargas is a member of the Center for Electronics and Telecommunications, Tecnológico de Monterrey, Mexico. Frantz Bouchereau is a senior communications software developer at The MathWorks Inc. in Natick, MA. Rogerio Enríquez-Caldera is at Instituto Nacional de Atrofisica, Optica y Electronica (INAOE), Puebla, Mexico. Contains a complete guide to models, techniques and applications of position location Includes applications to wireless networks (WiFi, ZigBee, DVB networks), cognitive radio, sensor networks and reconfigurable and multi-hop networks, demonstrating the relevance of location positioning to these ‘hot’ areas in research and development Covers system design trade-offs, and the design of efficient positioning algorithms enables the creation of future location positioning systems Provides a theoretical underpinning for understanding current position location algorithms, giving researchers a foundation to develop future algorithms

Download or read book Wireless Networks Model and Optimization Based Approaches to Clock Synchronization Random Access MAC and Video Streaming written by Nikolaos M. Freris and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We, via a model and optimization-based approach, address three issues related to wireless networks: clock synchronization, medium access control (MAC) and scalable video streaming. In Chapter 2 we develop, study and simulate a new model-based distributed network clock synchronization protocol. In a network of clocks, a given node is taken as reference and is associated with the time evolution t. We introduce and analyze a stochastic model for clocks, in which the relative speedup of a clock with respect to the reference node, called the skew, is characterized by an exponential transformation of an Orstein-Uhlenbeck process. We study the properties of our model, namely moment and sample path properties of the stochastic processes, and calculate its Allan variance. We show how our model can be used to translate the time of a clock to another clock's units. We study the problem of synchronizing clocks in a network, which amounts to estimating the instantaneous relative skews and relative offsets, i.e., the differences in the clock readouts, by exchange of time-stamped packets between pairs of nodes in the network. Based on a stochastic model for delays, we derive a scheme for obtaining relative skew measurements in a communication link by sending two time-stamped packets from node i to node j in order to obtain a noisy measurement of their relative skew. We develop an algorithm for filtering relative skew measurements across a link (i,j) in order to estimate the logarithm of the relative skew. We study the properties of the algorithms and provide theoretical guarantees on their performance. We also develop an online, centralized, model-based, asynchronous skew estimation algorithm for optimal filtering of the time-stamps in the entire network, as well as an efficient distributed suboptimal scheme which demonstrates near-optimal performance in simulations. Furthermore, we study some implementation issues, and present a scheme for pairwise relative offset estimation given skew estimates. We use the distributed asynchronous algorithm to obtain nodal offset estimates from relative offset estimates. We combine our findings into developing a new protocol for clock synchronization, namely the Model-Based Clock Synchronization Protocol (MBCSP). We present a comparative simulation study of its performance versus the leading scheme by Solis et al. (2006); the results show that MBCSP performs better in terms of skew, offset and delay estimation. Finally, we have performed trace-driven simulation based on time-stamps obtained from Berkeley motes. Our scheme outperforms that of Solis et al. by 45%, where we used the accuracy in predicting the receipt time-stamp at the sender as the clock synchronization metric. In Chapter 3, we study random access based MAC in the framework of network utility maximization (NUM). There has been much recent interest in protocol design for wireless networks based on maximizing a network utility function. A significant advance is the observation that a decomposition of the Lagrangian suggests an approach where transmissions are scheduled to minimize back-pressure. However, a satisfactory MAC protocol that can realize such a scheduling algorithm is notably missing, and we develop one potential scheme. We present a candidate random access MAC protocol that extends an existing algorithm by Gupta and Stolyar (2006) in calculating the access probabilities. We also consider the online adaptation of access probabilities using local information about queue lengths and active links. We provide OPNET simulation results to compare the performance of our scheme with the leading schemes. We estimate the capacity region of our scheme by simulation for various topologies and multiple flows. Our simulation studies indicate that our extension in conjunction with an implementation of back-pressure significantly outperforms the slotted-time algorithm of Gupta and Stolyar (2006). In Chapter 4, we present performance bounds for random access based MAC using carrier-sense multiple access (CSMA). In recent work, it was shown that a distributed CSMA-based MAC protocol is throughput-optimal which, in turn, implies that the class of controlled distributed random access MAC protocols can support the entire capacity region. It is challenging to study the performance of such schemes in terms of mean delays and compare it with some known results on the performance of centralized scheduling. We modify the model of Jiang and Walrand (2008) to obtain Markov chain models that incorporate the queue lengths as well as the information about the independent set, for single-hop networks. We show that the delay of the new models yields an upper bound on the delay of the original models. We derive upper and lower bounds on the mean total delay at the steady-state, and show that these bounds coincide with those for max-weight scheduling. Finally, we develop a method of deriving upper and lower bounds for random-access schemes by using linear programs (LPs). We present an optimization program for minimizing the upper bounds. In Chapter 5, we consider multihomed scalable video streaming systems where each video is concurrently transmitted over several access networks to a client. The problem is to determine which video packets of a video stream to transmit, and associate each video packet with an access network, so that the video quality at the client is maximized under measured network conditions. We present a network model and a video distortion model to capture the network conditions and video distortion characteristics, respectively. We develop a mathematical formulation to find the streaming strategy for maximizing the average video quality at the client. While the formulation can be optimally solved using exhaustive search or dynamic programming, doing so takes a prohibitively long time, and is not practical for real-time video streaming servers. In order to efficiently solve the problem in real time, we propose several suboptimal convex problems along with two heuristic algorithms. We conduct extensive trace-driven simulations to evaluate the algorithms using real network conditions and actual scalable video streams. We compare our algorithms against the rate control algorithms defined in the Datagram Congestion Control Protocol (DCCP) standard. The simulation results show that our algorithms significantly outperform current systems while being TCP-friendly. For example, compared to DCCP, our algorithms achieve at least 10 dB quality improvement and result in up to 83% packet delivery delay reduction. Finally, we study the trade-off between efficiency and optimality: One of the heuristic algorithms runs faster and is suitable for large-scale streaming systems, while the other one achieves better video quality and is more appropriate for smaller streaming servers. The convex programming approach demonstrates a good trade-off between running time and performance.

Download or read book Improving the Performance of Wireless LANs written by Nurul Sarkar and published by CRC Press. This book was released on 2014-01-08 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: While there are countless books on wireless networks, few actually quantify the key performance-limiting factors of wireless local area networks (WLANs) and describe various methods for improving WLAN performance. Fulfilling these needs, Improving the Performance of Wireless LANs: A Practical Guide provides both theoretical background and empirical results for the optimum planning and deployment of high performance WLAN systems in different residential and commercial buildings. Useful to students, faculties, researchers, engineers, and network developers, this must-have book not only explains the fundamentals of WLAN systems, including WLAN features and standards, but also: Supplies strategic guidelines for WLAN system design, modeling, and performance evaluation Includes radio propagation and site measurements as well as simulations for various network design scenarios Discusses environmental effects on WLAN performance, protocol redesign for routing and MAC, and traffic distribution Contains numerous illustrations and examples, plus chapter summaries, review questions, reading lists, mini-projects, an extensive glossary, and a list of acronyms Examines emerging and future network technologies, such as next generation Wi-Fi (802.11ac), very high throughput Wi-Fi (802.11ad), wireless mesh networking (802.11s), emergency QoS (802.11u), and vehicle-to-vehicle communications (802.11p) Improving the Performance of Wireless LANs: A Practical Guide makes the teaching, learning, and researching of advanced wireless network design and performance a more active process by using practical tools and exercises to add life to this highly technical subject.

Download or read book Protocols and Architectures for Wireless Sensor Networks written by Holger Karl and published by John Wiley & Sons. This book was released on 2005-11-01 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn all you need to know about wireless sensor networks! Protocols and Architectures for Wireless Sensor Networks provides a thorough description of the nuts and bolts of wireless sensor networks. The authors give an overview of the state-of-the-art, putting all the individual solutions into perspective with one and other. Numerous practical examples, case studies and illustrations demonstrate the theory, techniques and results presented. The clear chapter structure, listing learning objectives, outline and summarizing key points, help guide the reader expertly through the material. Protocols and Architectures for Wireless Sensor Networks: Covers architecture and communications protocols in detail with practical implementation examples and case studies. Provides an understanding of mutual relationships and dependencies between different protocols and architectural decisions. Offers an in-depth investigation of relevant protocol mechanisms. Shows which protocols are suitable for which tasks within a wireless sensor network and in which circumstances they perform efficiently. Features an extensive website with the bibliography, PowerPoint slides, additional exercises and worked solutions. This text provides academic researchers, graduate students in computer science, computer engineering, and electrical engineering, as well as practitioners in industry and research engineers with an understanding of the specific design challenges and solutions for wireless sensor networks. Check out www.wiley.com/go/wsn for accompanying course material! "I am deeply impressed by the book of Karl & Willig. It is by far the most complete source for wireless sensor networks...The book covers almost all topics related to sensor networks, gives an amazing number of references, and, thus, is the perfect source for students, teachers, and researchers. Throughout the book the reader will find high quality text, figures, formulas, comparisons etc. - all you need for a sound basis to start sensor network research." Prof. Jochen Schiller, Institute of Computer Science, Freie Universität Berlin

Download or read book Wireless MAC Protocol Design and Analysis written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless networks are becoming very common due to their advantages such as rapid deployment and support for mobility. In this dissertation, we design and analyze the Medium Access Control (MAC) protocol for two popular wireless networks: Wireless Sensor Networks (WSNs) and Wireless Local Area Networks (WLANs). For WSNs, we design and analyze an energy efficient MAC protocols. Energy efficiency is a key design factor of a MAC protocol for WSNs. Existing preamble-sampling based MAC protocols have large overheads due to their preambles and are inefficient at large wakeup intervals. Synchronous scheduling MAC protocols minimize the preamble by combining preamble sampling and scheduling techniques; however, they do not prevent energy loss due to overhearing. In this dissertation, we present an energy efficient MAC protocol for WSNs, called AS-MAC, that avoids overhearing and reduces contention and delay by asynchronously scheduling the wakeup time of neighboring nodes. We also provide a multi-hop energy consumption model for AS-MAC. To validate our design and analysis, we implement the proposed scheme on the MICAz and TELOSB platforms. Experimental results show that AS-MAC considerably reduces energy consumption, packet loss and delay when compared with other energy efficient MAC protocols. For WLANs, we present a saturation throughput model for IEEE 802.11, the standard of WLAN, for a simple infrastructure scenario with hidden stations. Despite the importance of the hidden terminal problem, there have been a relatively small number of studies that consider the effect of hidden terminals on IEEE 802.11 throughput. Moreover, existing models are not accurate for scenarios with the short-term unfairness. In this dissertation, we present a new analytical saturation throughput model for IEEE 802.11 for a simple but typical infrastructure scenario with small number of hidden stations. Simulation results are used to validate the model and show that our model is extremely accura.

Download or read book Listen and Talk written by Yun Liao and published by Springer. This book was released on 2016-06-15 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: This brief focuses on the use of full-duplex radio in cognitive radio networks, presenting a novel spectrum sharing protocol that allows the secondary users to simultaneously sense and access the vacant spectrum. This protocol, called “Listen-and-talk” (LAT), is evaluated by both mathematical analysis and computer simulations in comparison with other existing protocols, including the listen-before-talk protocol. In addition to LAT-based signal processing and resource allocation, the brief discusses techniques such as spectrum sensing and dynamic spectrum access. The brief proposes LAT as a suitable access scheme for cognitive radio networks, which can support the quality-of-service requirements of these high priority applications. Fundamental theories and key techniques of cognitive radio networks are also covered. Listen and Talk: Full-duplex Cognitive Radio Networks is designed for researchers, developers, and professionals involved in cognitive radio networks. Advanced-level students studying signal processing or simulations will also find the content helpful since it moves beyond traditional cognitive radio networks into future applications for the technology.

Download or read book Fundamental Concepts on Wireless LAN and the IEEE 802 11 Protocol written by Dereje Yohannes Ashenafi and published by Dereje Yohannes. This book was released on 2011 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wireless Network Design written by Jeff Kennington and published by Springer Science & Business Media. This book was released on 2010-11-10 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book surveys state-of-the-art optimization modeling for design, analysis, and management of wireless networks, such as cellular and wireless local area networks (LANs), and the services they deliver. The past two decades have seen a tremendous growth in the deployment and use of wireless networks. The current-generation wireless systems can provide mobile users with high-speed data services at rates substantially higher than those of the previous generation. As a result, the demand for mobile information services with high reliability, fast response times, and ubiquitous connectivity continues to increase rapidly. The optimization of system performance has become critically important both in terms of practical utility and commercial viability, and presents a rich area for research. In the editors' previous work on traditional wired networks, we have observed that designing low cost, survivable telecommunication networks involves extremely complicated processes. Commercial products available to help with this task typically have been based on simulation and/or proprietary heuristics. As demonstrated in this book, however, mathematical programming deserves a prominent place in the designer's toolkit. Convenient modeling languages and powerful optimization solvers have greatly facilitated the implementation of mathematical programming theory into the practice of commercial network design. These points are equally relevant and applicable in today’s world of wireless network technology and design. But there are new issues as well: many wireless network design decisions, such as routing and facility/element location, must be dealt with in innovative ways that are unique and distinct from wired (fiber optic) networks. The book specifically treats the recent research and the use of modeling languages and network optimization techniques that are playing particularly important and distinctive roles in the wireless domain.

Download or read book Security Design and Architecture for Broadband and Wireless Network Technologies written by Chilamkurti, Naveen and published by IGI Global. This book was released on 2013-04-30 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: While wireless technologies continue to provide an array of new challenges and multi-domain applications for business processes and solutions, there still remains to be a comprehensive understanding of its various dimensions and environments. Security, Design, and Architecture for Broadband and Wireless Network Technologies provides a discussion on the latest research achievements in wireless networks and broadband technology. Highlighting new trends, applications, developments, and standards, this book is essential for next generation researchers and practitioners in the ICT field.

Download or read book Advances in Wireless Networks written by Geyong Ming and published by Nova Publishers. This book was released on 2007 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent years have witnessed tremendous growth in the population of mobile users demanding high performance, reliability and quality-of-service (QoS). Wireless networks are undergoing rapid developments and dramatic changes in the underlying technologies, in order to cope with the difficulties posed by the scarce wireless resource as well as keep up with the increasing day-to-day demand for cost-effective service of multimedia applications. Predicting and optimising the performance and QoS of wireless networks using analytical modelling, simulation experiments, monitoring and testbed-based measurements are crucial to the proper design, tuning, resource management and capacity planning of such networks. This book is dedicated to review important developments and results, explore recent state-of-the-art research and discuss new strategies for performance modelling, analysis and enhancement of wireless networks. The objective is to make analytical modelling, simulation and measurement tools, and innovative performance evaluation methodology possible and understandable to a wider audience.