Download or read book Directional Collision Avoidance in Ad Hoc Networks written by and published by . This book was released on 2004 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper analyzes the performance of directional collision avoidance schemes, in which antenna systems are used to direct the transmission and reception of control and data packets in channel access protocols based on four-way handshakes to try to avoid collisions. The first analytical model to consider directional reception and the possible difference in gain between omni-directional and directional transmissions is presented. Analytical results show that, when the directional collision avoidance scheme in which all transmissions are directional is augmented with directional receiving, one-hop throughput does not decrease due to the increased spatial reuse, even when the number of competing nodes within a region increases. It is also shown that, as expected, the performance of directional collision avoidance schemes degrades when directional transmissions have much higher gain than omni-directional transmissions. However, this degradation is relatively small. Simulations of the IEEE 802.11 protocol and its directional variants validate the results predicted in the analysis. The simulation results also show that the presence of broadcast traffic does not degrade the performance of the all-directional collision avoidance scheme significantly, even for relatively large percentages of broadcast traffic. The performance results of this study indicate that the most attractive collision avoidance approach consists of using directional transmissions of control and data packets, together with the directional reception of packets whenever a node is expecting a particular packet. Given the high tolerance to broadcast traffic of directional collision avoidance schemes, it is argued that the periodic transmission of beacons omni-directionally suffices to provide such schemes with the relative location of neighboring nodes.
Download or read book Spatial Reuse and Collision Avoidance in Ad Hoc Networks with Directional Antennas written by and published by . This book was released on 2002 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The quest for efficient medium access control (MAC) protocols for multi-hop ad hoc networks has aroused great interest in using directional antennas. Some MAC protocols using directional antennas have been proposed in the past, which trade off spatial reuse and collision avoidance via a combination of omni-directional and directional transmission modes. In this paper, the authors argue that the benefit of spatial reuse achieved by a MAC protocol that uses directional mode in all transmissions can outweigh the benefit of a conservative collision avoidance MAC protocol that sends some omni-directional control packets to silence potential interfering nodes. Detailed simulation experiments of the popular IEEE 802.11 MAC protocol and its variants that make use of directional transmission mode in sufficiently random networks are presented. It is concluded that, in contention-based MAC protocols for multi-hop networks infested with hidden terminals, the aggressive channel access scheme featured by all-directional transmissions indeed outperforms other conservative schemes in terms of enhanced throughput and reduced delay.
Download or read book Collision Avoidance in Single Channel Ad Hoc Networks Using Directional Antennas written by and published by . This book was released on 2003 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three collision-avoidance protocols are analyzed that use omni-directional packet reception together with omni-directional transmissions, directional transmissions, or a combination of both. A simple model is introduced to analyze the performance of these collision avoidance protocols in multi-hop networks with arbitrary topologies. The numerical results of this analysis show that collision avoidance using a narrow antenna beamwidth for the transmission of all control and data packets achieves the highest throughput among the three collision avoidance schemes considered. Simulation experiments of the popular IEEE 802.11 MAC protocol and its variants based on directional transmissions and omni-directional packet reception validate the results predicted in the analysis. The results further show that narrow-beamwidth transmissions also can reduce the average delay experienced by nodes. It is concluded that the advantage of spatial reuse achieved by narrow-beamwidth transmissions outweighs that of conservative collision avoidance schemes featured by the omni-directional transmission of some control packets. This is because the latter requires far more stringent coordination of nodes with their neighbors and hidden terminals, which can lead to much more channel resource wasted due to nodes' excessive waiting time.
Download or read book Medium Access Control in Ad Hoc Networks with Omni directional and Directional Antennas written by Yu Wang and published by . This book was released on 2004 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: An ad hoc network is a dynamic network formed on demand by a group of nodes without the aid of any pre-existing network infrastructure. An efficient and effective medium access control (MAC) protocol which regulates nodes access to the shared channel(s) is essential in an ad hoc network. Our work is focused on the throughput and fairness properties of existing omni-directional MAC protocols as well as enhancement of their performance with directional antennas via both analytical and simulation approaches. In the first part, we present the first analytical modeling of collision avoidance MAC protocols including the popular IEEE 802.11 MAC protocol in multi-hop ad hoc networks. We show that in ad hoc networks with a lot of hidden terminals, collision avoidance even if done correctly, can still limit achievable throughput significantly because of the much reduced spatial reuse. Then we advance the analytical modeling to evaluate those MAC protocols which use directional antennas and can achieve much higher throughput through directing transmissions and receptions to desired directions only. We show that the gain in spatial reuse outweighs that of collision avoidance and hence an aggressive all-directional scheme is more advantageous than other hybrid schemes that take conservative (or unnecessary) tradeoff between collision avoidance and spatial reuse. All the analytical work has provided very useful insight on the interaction between spatial reuse, interference reduction and collision avoidance that previous work lacked.
Download or read book New Topics in Theoretical Computer Science written by Oleg N. Terikhovsky and published by Nova Publishers. This book was released on 2008 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical computer science focuses on the more abstract, logical and mathematical aspects of computing, such as the theory of computation, analysis of algorithms and semantics of programming languages. This new book presents the latest research in the field from around the globe.
Download or read book Networking 2004 written by Nikolas Mitrou and published by Springer Science & Business Media. This book was released on 2004-04-28 with total page 1551 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the Third IFIP-TC6 Networking Conference, NETWORKING 2004, held in Athens, Greece, in May 2004. The 103 revised full papers and 40 revised short papers were carefully reviewed and selected from 539 submissions. The papers are organized in topical sections on network security; TCP performance; ad-hoc networks; wavelength management; multicast; wireless network performance; inter-domain routing; packet classification and scheduling; services and monitoring; admission control; competition in networks; 3G/4G wireless systems; MPLS and related technologies; flow and congestion control; performance of IEEE 802.11; optical networks; TCP and congestion; key management; authentication and DOS prevention; energy aspects of wireless networks; optical network access; routing in ad-hoc networks; fault detection, restoration, and tolerance; QoS metrics, algorithms, and architecture; content distribution, caching, and replication; and routing theory and path computation.
Download or read book Beamforming Antennas in Wireless Networks written by Osama Bazan and published by Springer Nature. This book was released on 2021-07-08 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless networks are facing growing demand for high capacity, better coverage, support of new applications and broad range of services. In this book, the authors first present an overview of beamforming antennas and millimeter wave communications followed by a discussion on the challenges and issues facing MAC and multi-hop routing in the wireless networks with beamforming antennas. Then, they discuss various MAC and routing protocols that are specifically designed to address those issues and exploit the benefits of millimeter wave and beamforming antennas. Authors also present a framework to provide Quality of Service (QoS) in contention-based wireless networks with beamforming antennas. Finally, the book is concluded with a discussion on open research topics for future generation WLAN systems.
Download or read book Enhancing the Performance of Ad Hoc Wireless Networks with Smart Antennas written by Somprakash Bandyopadhyay and published by CRC Press. This book was released on 2016-04-19 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large portion of the network capacity of an ad hoc network can be wasted by the medium access mechanisms of omni-directional antennas. To overcome this problem, researchers propose the use of directional or adaptive antennas that largely reduce radio interference, improving the utilization of wireless medium and the resulting network throughput.
Download or read book AD HOC NETWORKS written by Prasant Mohapatra and published by Springer Science & Business Media. This book was released on 2006-01-16 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt: AD HOC NETWORKS: Technologies and Protocols is a concise in-depth treatment of various constituent components of ad hoc network protocols. It reviews issues related to medium access control, scalable routing, group communications, use of directional/smart antennas, network security, and power management among other topics. The authors examine various technologies that may aid ad hoc networking including the presence of an ability to tune transmission power levels or the deployment of sophisticated smart antennae. Contributors to this volume include experts that have been active in ad hoc network research and have published in the premier conferences and journals in this subject area. AD HOC NETWORKS: Protocols and Technologies will be immensely useful as a reference work to engineers and researchers as well as to advanced level students in the areas of wireless networks, and computer networks.
Download or read book Handbook of Research on Progressive Trends in Wireless Communications and Networking written by Matin, M.A. and published by IGI Global. This book was released on 2014-02-28 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This book brings together advanced research on diverse topics in wireless communications and networking, including the latest developments in broadband technologies, mobile communications, wireless sensor networks, network security, and cognitive radio networks"--
Download or read book Parallel and Distributed Processing and Applications written by Minyi Guo and published by Springer Science & Business Media. This book was released on 2006-11-27 with total page 971 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 4th International Symposium on Parallel and Distributed Processing and Applications, ISPA 2006, held in Sorrento, Italy in November 2006. The 79 revised full papers presented together with five keynote speeches cover architectures, networks, languages, algorithms, middleware, cooperative computing, software, and applications.
Download or read book Handbook on Advancements in Smart Antenna Technologies for Wireless Networks written by Sun, Chen and published by IGI Global. This book was released on 2008-07-31 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides information on smart antenna technologies featuring contributions with in-depth descriptions of terminologies, concepts, methods, and applications related to smart antennas in various wireless systems.
Download or read book Using Heterogeneous Networks for Intersection Collision Avoidance written by Lung-Chih Tung and published by . This book was released on 2014 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vehicular Ad-Hoc Network (VANET) is one of the most active research areas in ad hoc networks. In VANETs, each vehicle is equipped with wireless device so that it can communicate with other vehicles. With this capability, new applications targeting safety, entertainment, and better driving experience can be developed. The most urgent applications that arise much attention are the vehicular safety applications. Most safety applications can be achieved by exchanging small data packets called beacons. Beacons contain the position information of vehicles. By analyzing the position information, a warning can be issued when a potential collision is identified. However, some applications require warning messages to be disseminated multiple hops away, so a multiple hop data dissemination protocol is needed in these cases. To disseminate data efficiently, directional broadcast was proposed. The key idea is to select one relay node in each selected directions so that data can be propagated to all vehicles. However, it causes misclassification problem which results in inefficient and unreliable data propagation. For intersection collision avoidance, new concerns need to be taken care of. In urban area, the wireless communication can be blocked by buildings around the corner. Previous research shows that the line-of-sight condition in urban area is not good enough for identifying potential collisions within sufficient time before impact. Therefore, a road side unit installed in the center of an intersection is necessary in order to rebroadcast beacons to vehicles around the intersection. This incurs additional cost of the deployment of VANET infrastructure. The first part of this thesis explores the details of directional broadcast in terms of performance, and proposes a novel map-based directional broadcast protocol. We also incorporate a retransmission mechanism if transmission is regarded as failed to overcome the unreliable wireless communication. Store-carry-forward approach is used to increase the delivery ratio and efficiency. Moreover, we propose a solution to improve the safety of bicyclists using camera and DSRC. Simulations show that the map-based relay selection protocol can select relay nodes efficiently, and the retransmission combined with store-carry-forward approach increases delivery ratio significantly. For intersection collision avoidance, the original plan of connected vehicle project includes the deployment of massive number of road-side units at intersections. Due to the cost, the deployment of road-side units has been indefinitely postponed. Without road-side units, data cannot be propagated well at intersections in urban area because the line-of-sight transmission could be blocked by buildings around the corner. Aiming on this, LTE has been proposed as an alternative to overcome this problem. We analyze and evaluate the possibility of using LTE for intersection collision avoidance service. Based on our study, LTE should be able to provide satisfactory delay and bandwidth for limited number of users. In order to improve the bandwidth usage, we propose a cluster architecture using both short range and long range communication technology. Meanwhile, a prioritization scheme can also be used to provide service to users who need it most. We envision a world with safe and entertaining journey in the future with the popularity of VANET applications.
Download or read book Leadership and Personnel Management Concepts Methodologies Tools and Applications written by Management Association, Information Resources and published by IGI Global. This book was released on 2016-02-17 with total page 2308 pages. Available in PDF, EPUB and Kindle. Book excerpt: ###############################################################################################################################################################################################################################################################
Download or read book Advances in Vehicular Ad Hoc Networks Developments and Challenges written by Watfa, Mohamed and published by IGI Global. This book was released on 2010-05-31 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This book tackles the prevalent research challenges that hinder a fully deployable vehicular network, presenting a unified treatment of the various aspects of VANETs and is essential for not only university professors, but also for researchers working in the automobile industry"--Provided by publisher.
Download or read book Mobile Ad Hoc Networking written by Stefano Basagni and published by John Wiley & Sons. This book was released on 2004-10-07 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: From physical issues up to applications aspects, Mobile Ad Hoc Networking comprehensively covers all areas of the technology, including protocols and models, with an emphasis on the most current research and development in the rapidly growing area of ad hoc networks. All material has been carefully screened for quality and relevance and reviewed by the most renowned and involved experts in the field. Explores the most recent research and development in the rapidly growing area of ad hoc networks. Includes coverage of ad hoc networking trends, possible architectures, and the advantages/limits for future commercial, social, and educational applications. Ad hoc networks have been an intense area of research and development but many products that fully utilize this technology are only now being widely deployed throughout the world.
Download or read book Ad Hoc Mobile and Wireless Networks written by Violet R. Syrotiuk and published by Springer Science & Business Media. This book was released on 2005-09-28 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 4th International Conference on Ad-Hoc Networks and Wireless, ADHOC-NOW 2005, held in Cancun, Mexico in October 2005. The 27 revised full papers presented together with the abstracts of 2 invited talks were carefully reviewed and selected from over 100 submissions. The papers discuss architectures, protocols, and algorithms for: access control, scheduling, ad hoc and sensor networks analytic methods and modelling for performance evaluation, characterization, optimization, auto-configuration, incentives and pricing, location awareness, discovery, dependence, and management, mesh networks, new applications, power management, power control, and energy-efficiency, quality-of-service, resource allocation, multimedia, routing (unicast, multicast, etc.), security and privacy, service discovery, systems and testbeds, wireless internet, and data management.
