Access Control In Adhoc Networks

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Medium Access Control In Ad Hoc Networks With Omni Directional And Directional Antennas

Author : Yu Wang
ISBN : UCAL:X68066
Genre : Computer network protocols
File Size : 60.33 MB
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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.
Category: Computer network protocols

Security In Ad Hoc And Sensor Networks

Author : Raheem Beyah
ISBN : 9789814271080
Genre : Computers
File Size : 22.6 MB
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Security issues in ad hoc and sensor networks have become extremely important. This edited book provides a comprehensive treatment for security issues in these networks, ranging from attack mitigation to recovery after an attack has been successfully executed. Security issues addressed include (but are not limited to) attacks, malicious node detection, access control, authentication, intrusion detection, privacy and anonymity, key management, location verification, security architectures and protocols, secrecy and integrity, network resilience and survivability, and trust models. This complete book provides an excellent reference for students, researchers, and industry practitioners related to these areas.
Category: Computers

Ad Hoc Networks

Author : Prasant Mohapatra
ISBN : 0387226907
Genre : Technology & Engineering
File Size : 44.89 MB
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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.
Category: Technology & Engineering

Distributed Medium Access Control In Wireless Networks

Author : Ping Wang
ISBN : 9781461466024
Genre : Computers
File Size : 41.58 MB
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This brief investigates distributed medium access control (MAC) with QoS provisioning for both single- and multi-hop wireless networks including wireless local area networks (WLANs), wireless ad hoc networks, and wireless mesh networks. For WLANs, an efficient MAC scheme and a call admission control algorithm are presented to provide guaranteed QoS for voice traffic and, at the same time, increase the voice capacity significantly compared with the current WLAN standard. In addition, a novel token-based scheduling scheme is proposed to provide great flexibility and facility to the network service provider for service class management. Also proposed is a novel busy-tone based distributed MAC scheme for wireless ad hoc networks and a collision-free MAC scheme for wireless mesh networks, respectively, taking the different network characteristics into consideration. The proposed schemes enhance the QoS provisioning capability to real-time traffic and, at the same time, significantly improve the system throughput and fairness performance for data traffic, as compared with the most popular IEEE 802.11 MAC scheme.
Category: Computers

Medium Access Control In Wireless Networks

Author : Hongyi Wu
ISBN : 1600219446
Genre : Technology & Engineering
File Size : 49.8 MB
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Wireless technologies and applications are becoming one of the fastest growing and most promising areas in recent years. To accommodate data transmission by multiple stations sharing the scarce wireless bandwidth, a medium access control (MAC) protocol plays a crucial role in scheduling packet transmission fairly and efficiently. The emerging wireless networks, such as ad-hoc networks, sensor networks or mesh networks, are mostly multi-hop based and in distributed manner, which brings a lot of problems and challenges in designing fine-tuned MAC protocols tailored for modern wireless network. In this book, the authors give complete and in-depth overviews to the classic medium access control algorithms and the related protocols, as well as their applications in various wireless data networks especially the most successful Wireless Local Area Networks (WLAN). The book consists of three major parts. Part I of this book, including Chapters 1-7, is emphasising on the fundamentals of medium access control algorithms and protocols. Chapter 1 provides an introduction to the wireless networks, such as overview of wireless networks, problems and challenges of the wireless networks, and the classifications of MAC protocols as well as the performance metrics. Chapter 2 introduces important collision resolution algorithms applied in medium access controls, for example, the splitting algorithm and the backoff algorithm. Chapter 3 reviews the hybrid access control algorithms that combine both contention and allocation schemes. A series of important collision avoidance schemes are introduced in Chapters 4-7 respectively, with a specific design goal covered in each chapter. Chapter 4 focuses on the multi-channel MAC protocols for collision avoidance; Chapter 5 introduces the concepts of power control and power management in medium access control and how they can be applied in MAC protocol design; Chapter 6 presents how to provide Quality-of- Service (QoS) to multimedia wireless networks, in either centralised or distributed manner; and Chapter 7 explains how the smart antennas can be applied in the medium access control to provide high channel throughput and low packet collision.
Category: Technology & Engineering

An Enhanced Medium Access Control Protocol For Ad Hoc Networks

Author : Priyadarshini Sabut
ISBN : 3838393473
Genre :
File Size : 60.14 MB
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Ad hoc Networks are the most popular networks and are useful in many application environments due to less cost and easy deployment at anytime anywhere. The efficiency of these networks depends on the performance and reliability of the medium access control (MAC) protocol applied in such networks. The IEEE 802.11 DCF MAC protocol for ad hoc networks suffers from the problem of bandwidth sharing due to presence of hidden and exposed nodes. This book discusses a MAC protocol that not only overcomes the problem of hidden and exposed nodes but also allows the hidden nodes to transmit and exposed nodes to receive without interfering with the ongoing transmission in their vicinity, thereby improving channel utilization. The proposed protocol outperforms IEEE 802.11 DCF MAC in terms of throughput and packet delivery ratio with a little cost of control overhead.

Medium Access Control Protocols In Mobile Ad Hoc Networks Using Directional Antennas

Author : Uma Reddy Sappidi
ISBN : OCLC:841572831
Genre :
File Size : 62.5 MB
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A mobile ad hoc network is a collection of mobile terminals equipped with wireless transceivers that form an autonomous network without any pre-planned infrastructure or centralized administration. Because of its constantly changing topology and limited battery power, the major challenging issue in such networks is the medium access control (MAC). Traditionally, mobile ad hoc networks use omnidirectional antennas. However, the use of directional antennas may potentially improve the MAC performance and decrease the power consumption in the nodes. The purpose of our research is to design some novel MAC protocols for mobile ad hoc networks using directional antennas and evaluate their performances.

Analytical Modeling Of Medium Access Control Protocols In Wireless Networks

Author : Marcelo Menezes Carvalho
ISBN : UCAL:X73991
Genre :
File Size : 79.18 MB
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A new modeling framework is introduced for the analytical study of medium access control (MAC) protocols operating in multihop wireless ad hoc networks, i.e., wireless networks characterized by the lack of any pre-existent infrastructure and where participating devices must cooperatively provide the basic functionalities that are common to any computer network. The proposed modeling framework focuses on the interactions between the physical (PHY) and MAC layers, and on the impact that each node has on the dynamics of every other node in the network. To account for the effects of both cross-layer interactions and the interference among all nodes, a novel linear model is introduced with which topology and PHY/MAC-layer aspects are naturally incorporated in what we define as interference matrices. A key feature of the model is that nodes can be modeled individually, i.e., it allows a per-node setup of many layer-specific parameters. Moreover, no spatial probability distribution or special arrangement of nodes is assumed; the model allows the computation of individual (per-node) performance metrics for any given network topology and radio channel model.

Managing Security Services In Heterogenous Networks

Author : R. Thandeeswaran
ISBN : 9781000285079
Genre : Computers
File Size : 65.66 MB
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A heterogeneous network is a network which connects computers and other devices with different operating systems, protocols, or access technologies. By definition, managing heterogenous networks is more difficult that homogenous networks. Confidentiality, integrity, availability (CIA) remain the foundation of security. This book sheds light upon security threats, defenses, and remediation on various networking and data processing domains, including wired networks, wireless networks, mobile ad-hoc networks, wireless sensor networks, and social networks through the prisms of confidentiality, integrity, availability, authentication, and access control. The book is broken into different chapters that explore central subjects and themes in the development of the heterogenous networks we see today. The chapters look at: Access control methods in cloud-enabled Internet of Things Secure routing algorithms for mobile ad-hoc networks Building security trust in mobile ad-hoc networks using soft computing methods The use and development of Blockchain technology, with a particular focus on the nonce-free hash generation in Blockchain Password authentication and keystroke biometrics Health care data analytics over Big Data Bluetooth: and its open issues for managing security services in heterogenous networks Managing Security Services in Heterogenous Networks will be a valuable resource for a whole host of undergraduate and postgraduate students studying related topics, as well as career professionals who have to effectively manage heterogenous networks in the workplace.
Category: Computers

Sender And Receiver Initiated Multiple Access Protocols For Ad Hoc Networks

Author : Asimakis E. Tzamaloukas
ISBN : UCAL:X67905
Genre : Computer network protocols
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This thesis focuses on the medium access control (MAC) layer. Many MAC protocols for wireless networks proposed or implemented to date are based on collision-avoidance handshakes between sender and receiver. The key objective of collision-avoidance handshakes is reducing or eliminating the collision of data packets from a source at any given receiver due to interference from packets from other sources. In the vast majority of these protocols, including the IEEE 802.11 standard, the handshake is sender-initiated, in that the sender asks the receiver for permission to transmit using a short control packet, and transmits only after the receiver sends a short clear-to-send notification. There are two main objectives in this work: analyze the effect of reversing the collision-avoidance handshake as a way to improve the performance of MAC protocols under any conditions in the network, and design MAC protocols that provide correct floor acquisition without carrier sensing or code pre-assignment. We show that receiver-initiated collision-avoidance MAC protocols not only outperform any sender-initiated ones, but also guarantee collision-free data transmission and seamless support for mobility by using simple, low-cost wireless radios. We study the effect of persistent carrier sensing in receiver- as well as sender-initiated MAC protocols. We extend our work to multi-channel radios and introduce novel collision-avoidance MAC protocols that eliminate the need for carrier sensing and code pre-assignment, and improve the utilization of the medium in the presence of unicast, multicast and broadcast traffic.
Category: Computer network protocols

Analysis And Design Of Efficient Medium Access Control Schemes For Vehicular Ad Hoc Networks

Author : Chŏng Han
ISBN : OCLC:858002892
Genre :
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In this dissertation, analysis and design of the efficient Medium Access Control (MAC) sub-layer schemes are considered for Vehicular Ad hoc Networks (VANE~s). The contributions of this study are three-fold. First, an analytical model based on Markov chain is developed in order to investigate the performance of the MAC sub-layer of the IEEE 802.11p for vehicular communications. The results indicate that single channel MAC sub-layers may not be adequate for the future Intelligent Transportation Systems (ITS). The analytical model is validated with the results from simulation-based analysis. Performance analysis based on simulations is given on MAC metrics such as throughput, access delay, packet delivery. Second, a multi-channel MAC protocol is proposed and comprehensively analyzed in terms of channel utilizing and Quality of service (QoS) differentiation for dense VANETs. It is demonstrated that the proposed scheme, namely Asynchronous Multichannel MAC with Distributed TDMA (AMCMACD), improves the system performance in terms of throughput, packet delivery rate, collision rate on service channels, load balancing, and service differentiation for dense vehicular networks. Third, to cope with the interference from contention with neighbours within two hops in large-scale networks, a Large-scale Asynchronous Multichannel MAC (LS-AMCMAC) is proposed. The proposed scheme outperforms other benchmark multichannel MAC schemes in large-scale networks, in terms of throughput, channel utilization, dissemination of emergency messages, and the collision rates on control and service channels.

Adaptive Medium Access Control For Internet Of Things Enabled Mobile Ad Hoc Networks

Author : Qiang Ye
ISBN : OCLC:988124638
Genre : Ad hoc networks (Computer networks)
File Size : 76.91 MB
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An Internet-of-Things (IoT) enabled mobile ad hoc network (MANET) is a self organized distributed wireless network, in which nodes can randomly move making the network traffic load vary with time. A medium access control (MAC) protocol, as a most important mechanism of radio resource management, is required in MANETs to coordinate nodes' access to the wireless channel in a distributed way to satisfy their quality of service (QoS) requirements. However, the distinctive characteristics of IoT-enabled MANETs, i.e., distributed network operation, varying network traffic load, heterogeneous QoS demands, and increased interference level with a large number of nodes and extended communication distances, pose technical challenges on MAC. An efficient MAC solution should achieve consistently maximal QoS performance by adapting to the network traffic load variations, and be scalable to an increasing number of nodes in a multi-hop communication environment. In this thesis, we develop comprehensive adaptive MAC solutions for an IoT-enabled MANET with the consideration of different network characteristics. First, an adaptive MAC solution is proposed for a fully-connected network, supporting homogeneous best-effort data traffic. Based on the detection of current network traffic load condition, nodes can make a switching decision between IEEE 802.11 distributed coordination function (DCF) and dynamic time division multiple access (D-TDMA), when the network traffic load reaches a threshold, referred to as MAC switching point. The adaptive MAC solution determines the MAC switching point in an analytically tractable way to achieve consistently high network performance by adapting to the varying network traffic load. Second, when heterogeneous services are supported in the network, we propose an adaptive hybrid MAC scheme, in which a hybrid superframe structure is designed to accommodate the channel access from delay-sensitive voice traffic using time division multiple access (TDMA) and from best-effort data traffic using truncated carrier sense multiple access with collision avoidance (T-CSMA/CA). According to instantaneous voice and data traffic load conditions, the MAC exploits voice traffic multiplexing to increase the voice capacity by adaptively allocating TDMA time slots to active voice nodes, and maximizes the aggregate data throughput by adjusting the optimal contention window size for each data node. Lastly, we develop a scalable token-based adaptive MAC scheme for a two-hop MANET with an increasing number of nodes. In the network, nodes are partitioned into different one-hop node groups, and a TDMA-based superframe structure is proposed to allocate different TDMA time durations to different node groups to overcome the hidden terminal problem. A probabilistic token passing scheme is adopted for packet transmissions within different node groups, forming different token rings. An average end-to-end delay optimization framework is established to derive the set of optimal MAC parameters for a varying network load condition. With the optimal MAC design, the proposed adaptive MAC scheme achieves consistently minimal average end-to-end delay in an IoT-based two-hop environment with a high network traffic load. This research on adaptive MAC provides some insights in MAC design for performance improvement in different IoT-based network environments with different QoS requirements.
Category: Ad hoc networks (Computer networks)