DOCSLIB.ORG

University of Cincinnati

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
University of Cincinnati UNIVERSITY OF CINCINNATI Date:___________________ I, _________________________________________________________, hereby submit this work as part of the requirements for the degree of: in: It is entitled: This work and its defense approved by: Chair: _______________________________ _______________________________ _______________________________ _______________________________ _______________________________ Modeling and Performance Analysis of Mobile Ad Hoc Networks A dissertation submitted to the Division of Graduate Studies and Research of The University of Cincinnati In partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY In the Department of Electrical & Computer Engineering and Computer Science of the College of Engineering by Xiaolong Li M.E., (EE), Huazhong University of Science & Technology, China, 2002. B.E., (EE), Huazhong University of Science & Technology, China, 1999. Thesis Advisor and Committee Chair: Dr. Qing-An Zeng February 23, 2006 Abstract Ad hoc networks are gaining increasing popularity in recent years because of their ease of deployment. No wired base station or infrastructure is supported, and each host communicates one another via packet radios. In ad hoc networks, nodes are mobile which bring many challenges, such as network connectivity, topology change, link characteristic, and etc. In this research work, a novel model to analyze the link stability in mobile ad hoc networks is proposed. In the proposed analytical model, between each communicating pair, one node is considered to be stationary while the other moves relative to it. With this method, the mobility models defined in this dissertation can be approximated as a fluid flow model. Using the result of the fluid flow model, the analytical model for the link duration is obtained, which is used to obtain the link holding time and the link breaking probability of a communicating pair. The distribution of a routing path duration and the routing path breaking probability are also obtained by extending the models of the link duration and the link breaking probability. These results of link and routing path stabilities are serviced as ground knowledge to obtain the performance of medium access control (MAC) protocol considering node mobility. 1 MAC protocols are a fundamental element that determines the efficiency in sharing the limited communication bandwidth of wireless channels. IEEE 802.11 distributed coordination function (DCF) MAC protocol is the most widely used MAC protocol in ad hoc networks due to its compatibility with the IEEE 802 protocol suite. Since the release of the IEEE 802.11 standard, many research efforts have been devoted to modeling the performance of this protocol. However, most of studies are confined to the stationary performance where the nodes are immobile. In this research work, we employ the link and routing path stability models to analyze the performance of the IEEE 802.11 DCF MAC protocol in dynamic environment. To the best of our knowledge, this is the first time to evaluate the performance of this protocol with mobility. Another contribution of this research work is to analyze the performance of the IEEE 802.11 DCF MAC protocol with capture effect. Currently, most analytical models assume that all received packets at the receiver have the same physical conditions (same power, same coding, etc), so when two or more nodes transmit their packets at the same time, the collision happens and all packets involved are destroyed, which may not be the case in reality due to capture effect. In this research work, we provide an analytical model to obtain the probability of capture effect. We use this probability of capture effect to analyze the throughput of the IEEE 802.11 DCF MAC protocol in ad hoc networks considering path loss, multipath fading, and shadowing. Wireless channel is time-varying and error prone. The packet transmission can be failed due to transmission errors. In this research work, a refined analytical 2 model is presented to evaluate the performance of the IEEE 802.11 DCF MAC protocol with time-varying wireless channel. In the proposed model, the time- varying wireless channel is modeled by a finite-state Markov (FSM) chain. In each channel state, the operation of the IEEE 802.11 DCF MAC protocol is modeled by an embedded Markov chain. Using this model, the throughput of the DCF protocol can be theoretically calculated. The results show that the performance of the DCF protocol strongly depends on the network size, the incoming traffic loads, and the bit error rate (BER). When the incoming traffic load is light, the throughput increases when the network size grows. When the network works under heavy (saturated) condition, the throughput decreases when the network size grows. The throughput always degrades when increasing BER regardless the network size and the traffic load. 3 Acknowledgements I am most grateful and indebted to my advisor, Professor Qing-An Zeng, for the large doses of guidance, patience, and encouragement he has shown me during my time here at The University of Cincinnati. He always found time whenever I needed an intelligent discussion. It is a pleasure, as well as a honor, to work with him. I am also grateful and indebted to Professor Dharma Agrawal, for inspiration and enlightening discussions on a wide variety of topics. I thank my other committee members, Professor Anca Ralescu, Professor James Caffery, and Professor Heng Wei, for their insightful commentary on my work. Also, I would like to extend my gratitude to the department staff members. My special thanks to Julie Muenchen and Teresa Hamad for making sure I stay out of trouble. Finally, I would like to express my deepest gratitude to my family and friends. I thank Duojia Zhu, my wife, who has been an endless source of encouragement and support through the most trying of times. I would like to extend my endless gratitude and love to my parents, without whom I would never have been able to think of embarking on such a journey. i Table of Contents 1 Introduction 1 1.1 Background and Motivation . 1 1.1.1 Wireless Local Area Networks . 1 1.1.2 Challenges in Ad Hoc Networks . 3 1.2 Contributions . 7 1.3 Organization of the dissertation . 8 1.4 Summary . 8 2 Overview of Mobility Models and MAC Protocols 9 2.1 Introduction . 9 2.2 Mobility Models . 10 2.2.1 Independent Mobility Models . 10 2.2.2 Group Mobility Models . 14 2.2.3 Other Mobility Parameters . 15 2.3 MAC Protocols . 15 2.3.1 Carrier Sense Multiple Access . 16 2.3.2 Multiple Access with Collision Avoidance . 16 ii 2.3.3 Floor Acquisition Multiple Access . 17 2.3.4 IEEE 802.11 Distributed Coordination Function . 18 2.4 Summary . 20 3 Link and Routing Path Stabilities in Mobile Ad Hoc Networks 21 3.1 Introduction . 21 3.2 System Model . 23 3.3 Analysis of Node Motion . 25 3.4 Analysis of Link Characteristics . 26 3.4.1 Link Duration . 27 3.4.2 Link Holding Time . 29 3.4.3 Link Breaking Probability . 30 3.5 Simulations and Discussions . 32 3.6 Summary . 39 4 Performance Analysis of MAC Protocol in Mobile Ad Hoc Net- works 41 4.1 Introduction . 41 4.2 Single-hop Ad Hoc Networks . 43 4.2.1 System Model . 43 4.2.2 Performance Analysis . 44 4.3 Multi-hop Ad Hoc Networks . 52 4.3.1 System Model . 52 4.3.2 Performance Analysis . 53 iii 4.4 Simulations and Discussions . 59 4.5 Summary . 61 5 Impact of Capture Effect on the Performance of MAC Protocol 63 5.1 Introduction . 63 5.2 Channel Model . 65 5.3 Capture Model . 67 5.4 Analytical Model . 70 5.5 Numerical Results and Discussions . 72 5.6 Summary . 76 6 Influence of Time-varying Channel on the Performance of MAC Protocol 79 6.1 Introduction . 79 6.2 Wireless Channel Model . 81 6.3 Analytical Model . 84 6.4 Numerical Results and Discussions . 89 6.5 Summary . 91 7 Conclusions and Future Work 94 7.1 Conclusions . 94 7.2 Future Work . 97 iv List of Figures 2.1 Illustration of hidden node problem . 17 2.2 Illustration of exposed node problem . 18 2.3 Basic CSMA/CA Protocol . 20 2.4 CSMA/CA with RTS/CTS protocol . 20 3.1 System model . 24 3.2 pdfs of link duration . 34 3.3 pdfs of routing path duration . 35 3.4 pdfs of link holding time . 37 3.5 Link breaking probability versus average virtual packet transmission time . 38 3.6 Routing path breaking probability versus average speed . 40 4.1 Embedded slots . 46 4.2 Markov chain model for the entire network . 46 4.3 Structure of time Tv .......................... 51 4.4 System model . 53 4.5 Illustration of hidden area . 54 v 4.6 Throughput of CSMA/CA protocol . 60 4.7 Throughput for basic CSMA/CA . 61 4.8 Throughput for CSMA/CA with RTS/CTS . 61 5.1 Spatial distribution of two arbitrary nodes in ad hoc networks . 66 5.2 pdf of distance R between any two nodes in ad hoc networks . 67 5.3 Capture probability in infrastructure mode (σs = 1.35) . 73 5.4 Capture probability in ad hoc mode (σs = 1.35) . 73 5.5 Capture probability in infrastructure mode (σs = 1.35) . 74 5.6 Capture probability in an ad hoc mode (σs = 1.35) . 74 5.7 Throughput of basic CSMA/CA versus traffic load G with capture model of the first category . 75 5.8 Throughput of CSMA/CA with RTS/CTS versus traffic load G with capture model of the first category . 76 5.9 Throughput of basic CSMA/CA versus traffic load G with capture model of the second category . 77 5.10 Throughput of CSMA/CA with RTS/CTS versus traffic load G with capture model of the second category .
Load more

Recommended publications
  • Reservation - Time Division Multiple Access Protocols for Wireless Personal Communications
    tv '2s.\--qq T! Reservation - Time Division Multiple Access Protocols for Wireless Personal Communications Theodore V. Buot B.S.Eng (Electro&Comm), M.Eng (Telecomm) Thesis submitted for the degree of Doctor of Philosophy 1n The University of Adelaide Faculty of Engineering Department of Electrical and Electronic Engineering August 1997 Contents Abstract IY Declaration Y Acknowledgments YI List of Publications Yrt List of Abbreviations Ylu Symbols and Notations xi Preface xtv L.Introduction 1 Background, Problems and Trends in Personal Communications and description of this work 2. Literature Review t2 2.1 ALOHA and Random Access Protocols I4 2.1.1 Improvements of the ALOHA Protocol 15 2.1.2 Other RMA Algorithms t6 2.1.3 Random Access Protocols with Channel Sensing 16 2.1.4 Spread Spectrum Multiple Access I7 2.2Fixed Assignment and DAMA Protocols 18 2.3 Protocols for Future Wireless Communications I9 2.3.1 Packet Voice Communications t9 2.3.2Reservation based Protocols for Packet Switching 20 2.3.3 Voice and Data Integration in TDMA Systems 23 3. Teletraffic Source Models for R-TDMA 25 3.1 Arrival Process 26 3.2 Message Length Distribution 29 3.3 Smoothing Effect of Buffered Users 30 3.4 Speech Packet Generation 32 3.4.1 Model for Fast SAD with Hangover 35 3.4.2Bffect of Hangover to the Speech Quality 38 3.5 Video Traffic Models 40 3.5.1 Infinite State Markovian Video Source Model 41 3.5.2 AutoRegressive Video Source Model 43 3.5.3 VBR Source with Channel Load Feedback 43 3.6 Summary 46 4.
    [Show full text]
  • 2009 IEEE 70Th Vehicular Technology Conference Fall
    2009 IEEE 70th Vehicular Technology Conference Fall (VTC 2009-Fall) Anchorage, Alaska, USA 20 – 23 September 2009 Pages 1-485 IEEE Catalog Number: CFP09VTF-PRT ISBN: 978-1-4244-2514-3 TABLE OF CONTENTS PORTABLE 2009 OPENING KEYNOTE SELF-ORGANIZING NETWORKS IN 3GPP LTE..........................................................................................................1 Seppo Hämäläinen 22W: ELECTRICAL DESIGN II NONINVASIVE CONTINUOUS BLOOD PRESSURE MEASUREMENT AND GPS POSITION MONITORING OF PATIENTS ..........................................................................................................................................3 Ondrej Krejcar, Zdenek Slanina, Jan Stambachr, Petr Silber And Robert Frischer NUMERICAL INVESTIGATION OF ALGORITHMS FOR MULTI-ANTENNA RADIOLOCATION ..............................................................................................................................................................8 Danko Antolovic WBAN MEETS WBAN: SMART MOBILE SPACE OVER WIRELESS BODY AREA NETWORKS.................... 13 Dae-Young Kim And Jinsung Cho AN ALGORITHM FOR SIMULTANEOUS RADIOLOCATION OF MULTIPLE SOURCES................................. 18 Danko Antolovic 2W: PHYSICAL DESIGN MICRO AND NANO ELECTRO MECHANICAL SYSTEMS (MEMS/NEMS) FOR MOBILE COMPUTING SYSTEMS .................................................................................................................................................. 23 M. Abdelmoneum, D. Browning, T. Arabi And Waleed Khalil BATTERY-SENSING INTRUSION PROTECTION SYSTEM
    [Show full text]
  • Etsi Tr 102 862 V1.1.1 (2011-12)
    ETSI TR 102 862 V1.1.1 (2011-12) Technical Report Intelligent Transport Systems (ITS); Performance Evaluation of Self-Organizing TDMA as Medium Access Control Method Applied to ITS; Access Layer Part 2 ETSI TR 102 862 V1.1.1 (2011-12) Reference DTR/ITS-0040021 Keywords ITS, MAC, TDMA ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88 Important notice Individual copies of the present document can be downloaded from: http://www.etsi.org The present document may be made available in more than one electronic version or in print. In any case of existing or perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF). In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at http://portal.etsi.org/tb/status/status.asp If you find errors in the present document, please send your comment to one of the following services: http://portal.etsi.org/chaircor/ETSI_support.asp Copyright Notification No part may be reproduced except as authorized by written permission.
    [Show full text]
  • Self-Stabilizing TDMA Algorithms for Wireless Ad-Hoc Networks Without External Reference
    2014 13th Annual Mediterranean Ad Hoc Networking Workshop (MED-HOC-NET) Self-stabilizing TDMA Algorithms for Wireless Ad-hoc Networks without External Reference (Extended Abstract) Thomas Petig, Elad M. Schiller, Philippas Tsigas {petig, elad, tsigas}@chalmers.se Department of Computer Science and Engineering Chalmers University of Technology, Sweden Abstract—Time division multiple access (TDMA) is a method needed MAC protocol properties, using limited radio and clock for sharing communication media. In wireless communications, settings, i.e., no external reference for collision detection, time TDMA algorithms often divide the radio time into timeslots of or position. Note that ad hoc networks often do not consider uniform size, ξ, and then combine them into frames of uniform size, τ. We consider TDMA algorithms that allocate at least collision detection mechanisms, and external references are one timeslot in every frame to every node. Given a maximal subject to signal loss. For these settings, we demonstrate node degree, δ, and no access to external references for collision that there is no solution for the studied problem when the detection, time or position, we consider the problem of collision- frame size is τ<max{2δ, χ2}, where δ is the maximal free self-stabilizing TDMA algorithms that use constant frame node degree, and χ2 is the chromatic number for distance-2 size. We demonstrate that this problem has no solution when vertex coloring. The main result is the existence of collision- the frame size is τ<max{2δ, χ2}, where χ2 is the chromatic free self-stabilizing TDMA algorithms that use constant frame number for distance-2 vertex coloring.
    [Show full text]
  • Data Link Layer
    Data Link Layer Sublayers: • Sublayers of the data link layer o Logical link control sublayer o Media access control sublayer Data link layer services: • Encapsulation of network layer data packets into frames • Frame synchronization- Done by Media Access Control sublayer • Logical link control (LLC) sublayer: o Error control (automatic repeat request, ARQ) o Flow control • Media access control (MAC) sublayer: o Multiple access protocols for channel-access control, for example CSMA/CD protocols for collision detection and re-transmission in Ethernet bus networks and hub networks, or the CSMA/CA protocol for collision avoidance in wireless networks. o Physical addressing (MAC addressing) o LAN switching (packet switching) including MAC filtering and spanning tree protocol o Data packet queuing or scheduling o Store-and-forward switching or cut-through switching o Quality of Service (QoS) control o Virtual LANs (VLAN) The uppermost sublayer, LLC, multiplexes protocols running atop the data link layer, and optionally provides flow control, acknowledgment, and error notification. More about MAC Sublayer: 1. The Media Access Control sublayer also determines where one frame of data ends and the next one starts – frame synchronization. There are four means of frame synchronization: time based, character counting, byte stuffing and bit stuffing. 2. The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network. 3. Store and forward is a telecommunications technique in which information is sent to an intermediate station where it is kept and sent at a later time to the final destination or to another intermediate station.
    [Show full text]
  • Unit-Iii Datalink Layer: Error Detection and Correction
    UNIT-III DATALINK LAYER: ERROR DETECTION AND CORRECTION Error-Correcting Codes Error control in computer networks is typically achieved by error detecting using cyclic redundancy check (CRC), which is the checksum inside a frame, combined with retransmission For this purpose, systematic cyclic or polynomial generated codes are often used, which are special linear block codesSome basic concepts in error control coding are first reviewedAn n-bit frame, which consists of m-bit data and r check bits, is called a codeword. AllCode words form the codebook Hamming distance between two code words is number of bits in which two code words differ For example, 10001001 and 10110001 have a Hamming distance of 3, where is bit-wise exclusive OR (modulo 2) The minimum Hamming distance d min of a codebook is the smallest Hamming distance between any pair of code words in the codebook A codebook with dmin can detect up to dmin − 1 errors and correct up to (dmin − 1)/2 errors in each codeword. Use of a Hamming code to correct burst errors Hamming codes can only correct single errors. However, there is a trick that can be used to permit Hamming codes to correct burst errors. A sequence of k consecutive codewords is arranged as a matrix, one codeword per row. Normally, the data would be transmitted one codeword at a time, from left to right. To correct burst errors, the data should be transmitted one column at a time, starting with the leftmost column. When all k bits have been sent, the second column is sent, and so on.
    [Show full text]
  • Medium Access Control for Vehicular Ad Hoc Networks KATRIN SJÖBERG ISBN 978-91-7385-832-8
    Thesis for the degree of Doctor of Philosophy Medium Access Control for Vehicular Ad Hoc Networks Katrin Sjöberg Department of Signals and Systems School of Information Science, Computer and Electrical Engineering CHALMERS UNIVERSITY OF TECHNOLOGY HALMSTAD UNIVERSITY Göteborg, Sweden, 2013 Medium Access Control for Vehicular Ad Hoc Networks KATRIN SJÖBERG ISBN 978-91-7385-832-8 Copyright Katrin Sjöberg, 2013. All rights reserved. Doktorsavhandlingar vid Chalmers tekniska högskola ISSN 1403-266X Ny serie nr 3513 Department of Signals and Systems CHALMERS UNIVERSITY OF TECHNOLOGY Hörsalsvägen 11 SE-412 96 Göteborg Sweden Telephone: +46 - (0)31 - 772 10 00 Fax: +46 - (0)31 - 772 36 63 Contact Information: Katrin Sjöberg School of Information Science, Computer and Electrical Engineering HALMSTAD UNIVERSITY SE-301 18 Halmstad Sweden Telephone: +46 - (0)35 - 16 71 00 Fax: +46 - (0)35 - 12 03 48 Email: [email protected] Printed in Sweden Chalmers Reproservice Göteborg, Sweden, 2013 Medium Access Control for Vehicular Ad Hoc Networks KATRIN SJÖBERG Department of Signals and Systems, Chalmers University of Technology Abstract Cooperative intelligent transport systems (C-ITS), where vehicles cooperate by exchanging messages wirelessly to avoid, for example, hazardous road traffic situations, receive a great deal of attention throughout the world currently. Many C-ITS applications will utilize the wireless communication technology IEEE 802.11p, which offers the ability of direct communication between vehicles, i.e., ad hoc communication, for up to 1000 meters. In this thesis, medium access control (MAC) protocols for vehicular ad hoc networks (VANET) are scrutinized and evaluated. The MAC protocol decides when a station has the right to access the shared communication channel and schedules transmissions to minimize the interference at receiving stations.
    [Show full text]
  • Agile Wireless Transmission Strategies
    Agile wireless transmission strategies Citation for published version (APA): Ho, C. K. (2009). Agile wireless transmission strategies. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR640214 DOI: 10.6100/IR640214 Document status and date: Published: 01/01/2009 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policy If you believe that this document breaches copyright please contact us at: [email protected] providing details and we will investigate your claim.
    [Show full text]
  • COST Action CA15104 Collaborative White Paper on Future Architecture and Protocols for Iot
    COST Action CA15104 Collaborative White Paper on Future Architecture and Protocols for IoT COST Action CA15104 (IRACON) aims to achieve scientific networking and cooperation in novel design and analysis methods for 5G, and beyond-5G, radio communication networks. The scientific activities of the action are organized according to two types of Working Groups: disciplinary and experimental Working Groups. In total, IRACON consists of 6 working groups: Radio Channels (DWG1), PHY layer (DWG2), NET Layer (DWG3), OTA Testing (EWG-OTA), Internet-of-Things (EWG-IoT), Localization and Tracing (EWG-LT) and Radio Access (EWG-RA). A sub-working group of EWG-IoT was also recently created: IoT for Health. This white paper focuses on the Internet of Things (IoT). First, it introduces the IoT field with a general definition and the main applications, with the related requirements. Then, a description of the technologies available nowadays is provided; for each technology the main key parameters are given, and some quantitative and/or qualitative key performance indicators are reported. The white paper concludes with a brief overview of IoT architectures and a mapping between the identified applications and the most appropriate technology. Editors: C. Anton, C. Buratti, L. Clavier, G. Gardasevic, E. Strom, R. Verdone Authors: L. O. Barbosa, T. Baykas, A. Bazzi, C. Buratti, L. Clavier, G. Gardasevic, S. Mignardi, E. Strom, R. Verdone Date: March 2019 Contents Contents ..............................................................................................................................................
    [Show full text]
  • Ethernet 95 Link Aggregation 102 Power Over Ethernet 107 Gigabit Ethernet 116 10 Gigabit Ethernet 121 100 Gigabit Ethernet 127
    Computer Networking PDF generated using the open source mwlib toolkit. See http://code.pediapress.com/ for more information. PDF generated at: Sat, 10 Dec 2011 02:24:44 UTC Contents Articles Networking 1 Computer networking 1 Computer network 16 Local area network 31 Campus area network 34 Metropolitan area network 35 Wide area network 36 Wi-Fi Hotspot 38 OSI Model 42 OSI model 42 Physical Layer 50 Media Access Control 52 Logical Link Control 54 Data Link Layer 56 Network Layer 60 Transport Layer 62 Session Layer 65 Presentation Layer 67 Application Layer 69 IEEE 802.1 72 IEEE 802.1D 72 Link Layer Discovery Protocol 73 Spanning tree protocol 75 IEEE 802.1p 85 IEEE 802.1Q 86 IEEE 802.1X 89 IEEE 802.3 95 Ethernet 95 Link aggregation 102 Power over Ethernet 107 Gigabit Ethernet 116 10 Gigabit Ethernet 121 100 Gigabit Ethernet 127 Standards 135 IP address 135 Transmission Control Protocol 141 Internet Protocol 158 IPv4 161 IPv4 address exhaustion 172 IPv6 182 Dynamic Host Configuration Protocol 193 Network address translation 202 Simple Network Management Protocol 212 Internet Protocol Suite 219 Internet Control Message Protocol 225 Internet Group Management Protocol 229 Simple Mail Transfer Protocol 232 Internet Message Access Protocol 241 Lightweight Directory Access Protocol 245 Routing 255 Routing 255 Static routing 260 Link-state routing protocol 261 Open Shortest Path First 265 Routing Information Protocol 278 IEEE 802.11 282 IEEE 802.11 282 IEEE 802.11 (legacy mode) 292 IEEE 802.11a-1999 293 IEEE 802.11b-1999 295 IEEE 802.11g-2003 297
    [Show full text]
  • Nuno Fábio Gomes Camacho Ferreira Controlo De Acesso Ao Meio
    Universidade de Aveiro Departamento de Eletrónica, Telecomunicações e Ano 2019 Informática Nuno Fábio Controlo de Acesso ao Meio em Comunicações Gomes Veiculares de Tempo-Real Camacho Ferreira Medium Access Control in Real-Time Vehicular Communications Universidade de Aveiro Departamento de Eletrónica, Telecomunicações e Ano 2019 Informática Nuno Fábio Controlo de Acesso ao Meio em Comunicações Gomes Veiculares de Tempo-Real Camacho Ferreira Medium Access Control in Real-Time Vehicular Communications Tese apresentada à Universidade de Aveiro para cumprimento dos requisitos necessários à obtenção do grau de Doutor em Engenharia Eletrotécnica. Apoio financeiro da FCT refª SFRH/BD/31212/2006 e do FSE no âmbito do III Quadro Comunitário de Apoio. Dedico este trabalho à minha esposa, Mónica, ao meu filho, Guilherme, à minha mãe, Paulina, e à minha sogra Filomena, que estará sempre comigo. o júri Presidente Doutor João Filipe Colardelle da Luz Mano, Professor Catedrático da Universidade de Aveiro Vogais Doutora Susana Isabel Barreto de Miranda Sargento, Professora Associada com Agregação da Universidade de Aveiro Doutor José Boaventura Ribeiro da Cunha, Professor Associado com Agregação da Universidade de Trás-os-Montes e Alto Douro Doutor Paulo José Lopes Machado Portugal, Professor Associado da Universidade do Porto Doutor José Alberto Gouveia Fonseca, Professor Associado da Universidade de Aveiro Doutor Mário Jorge de Andrade Ferreira Alves, Professor Coordenador do Instituto Superior de Engenharia do Porto agradecimentos Attaining a PhD degree may, sometimes, seem like an endless road, in which hard work and innovative ideas may not seem enough. However, that illusion may be suppressed with the support and encouragement of important people, which I did and owe gratitude to them.
    [Show full text]
  • Unit-Iii Datalink Layer: Error Detection and Correction
    UNIT-III DATALINK LAYER: ERROR DETECTION AND CORRECTION Error-Correcting Codes Error control in computer networks is typically achieved by error detecting using cyclic redundancy check (CRC), which is the checksum inside a frame, combined with retransmission For this purpose, systematic cyclic or polynomial generated codes are often used, which are special linear block codesSome basic concepts in error control coding are first reviewedAn n-bit frame, which consists of m-bit data and r check bits, is called a codeword. AllCode words form the codebook Hamming distance between two code words is number of bits in which two code words differ For example, 10001001 and 10110001 have a Hamming distance of 3, where is bit-wise exclusive OR (modulo 2) The minimum Hamming distance d min of a codebook is the smallest Hamming distance between any pair of code words in the codebook A codebook with dmin can detect up to dmin − 1 errors and correct up to (dmin − 1)/2 errors in each codeword. Use of a Hamming code to correct burst errors Hamming codes can only correct single errors. However, there is a trick that can be used to permit Hamming codes to correct burst errors. A sequence of k consecutive codewords is arranged as a matrix, one codeword per row. Normally, the data would be transmitted one codeword at a time, from left to right. To correct burst errors, the data should be transmitted one column at a time, starting with the leftmost column. When all k bits have been sent, the second column is sent, and so on.
    [Show full text]