Математичні моделі для спеціалізованих та сенсорних мереж бездротового доступу

Розглядаються та порівнюються особливості бездротових спеціалізованих та бездротових сенсорних мереж. Пропонуються для розгляду компоненти математичної моделі бездротових спеціалізованих та бездротових сенсорних мереж, зокрема моделі бездротового каналу, розповсюдження сигналу, комунікаційного графа та інші. Пояснюється необхідність механізмів контролю топології в бездротових спеціалізованих та сенсорних мережах.In this article the special features of wireless ad-hoc and sensor networks are reviewed and compared. Proposed is also the description of existing wireless ad-hoc and sensor network mathematical model components, in particular the model of wireless channel, signal propagation model, communication graph etc. The relevance of topology control mechanism in wireless ad-hoc and sensor networks is explained

LD: Identifying Misbehaving Nodes in MANET

A mobile ad-hoc network is a collection of mobile nodes connected together over a wireless medium without any fixed infrastructure. Unique characteristics of mobile ad-hoc networks such as open peer-to-peer network architecture, shared wireless medium and highly dynamic topology, pose various challenges to the security design. Mobile ad-hoc networks lack central administration or control, making them very vulnerable to attacks or disruption by faulty nodes in the absence of any security mechanisms. Also, the wireless channel in a mobile ad-hoc network is accessible to both legitimate network users and malicious attackers. So, the task of finding good solutions for these challenges plays a critical role in achieving the eventual success of mobile ad-hoc networks. However, the open medium and wide distribution of nodes make MANET vulnerable to malicious attackers. In this case, it is crucial to develop efficient intrusion-detection mechanisms to protect MANET from attacks. Secure routing protocols and mechanisms to detect routing misbehavior in the direct neighborhood exist; however, collusion of misbehaving nodes has not been adequately addressed yet. We present LeakDetector, a mechanism to detect colluding malicious nodes in wireless multihop networks A mobile ad-hoc network is a collection of mobile nodes connected together over a wireless medium without any fixed infrastructure. Unique characteristics of mobile ad-hoc networks such as open peer-to-peer network architecture, shared wireless medium and highly dynamic topology, pose various challenges to the security design. Mobile ad-hoc networks lack central administration or control, making them very vulnerable to attacks or disruption by faulty nodes in the absence of any security mechanisms. Also, the wireless channel in a mobile ad-hoc network is accessible to both legitimate network users and malicious attackers. So, the task of finding good solutions for these challenges plays a critical role in achieving the eventual success of mobile ad-hoc networks. However,the. LeakDetector enables the calculation of the packet-loss ratio for the individual nodes

Topology Control in Cooperative Ad Hoc Wireless Networks

AbstractCooperative communication (CC) is a technique that exploits spatial diversity allowing multiple nodes to cooperatively relay signals to the receiver so that it can combine the received signals to obtain the original message. CC can be combined with topology control to increase connectivity at the cost of a small increase in energy consumption. This work focuses on exploring CC to improve the connectivity with a sink node in ad hoc wireless networks. More precisely, this work proposes a new technique, named CoopSink, that combines CC and topology control techniques to increase connectivity to a sink node while ensuring energy-efficient routes. Simulation results show that connectivity and routing to the sink cost can be improved up to 6.8 and 2.3 times, respectively, when compared with other similar strategies

Application of game theory in ad- hoc opportunistic radios

The application of mathematical analysis to the study of wireless ad hoc networks has met with limited success due to the complexity of mobility, traffic models and the dynamic topology. A scenario based UMTS TDD opportunistic cellular system with an ad hoc behaviour that operates over UMTS FDD licensed cellular network is considered. In this paper, we describe how ad hoc opportunistic radio can be modeled as a game and how we apply game theory based Power Control in ad-hoc opportunistic radio

A survey on wireless ad hoc networks

A wireless ad hoc network is a collection of wireless nodes that can dynamically self-organize into an arbitrary and temporary topology to form a network without necessarily using any pre-existing infrastructure. These characteristics make ad hoc networks well suited for military activities, emergency operations, and disaster recoveries. Nevertheless, as electronic devices are getting smaller, cheaper, and more powerful, the mobile market is rapidly growing and, as a consequence, the need of seamlessly internetworking people and devices becomes mandatory. New wireless technologies enable easy deployment of commercial applications for ad hoc networks. The design of an ad hoc network has to take into account several interesting and difficult problems due to noisy, limited-range, and insecure wireless transmissions added to mobility and energy constraints. This paper presents an overview of issues related to medium access control (MAC), routing, and transport in wireless ad hoc networks and techniques proposed to improve the performance of protocols. Research activities and problems requiring further work are also presented. Finally, the paper presents a project concerning an ad hoc network to easily deploy Internet services on low-income habitations fostering digital inclusion8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Topology Control in Wireless ad Hoc and Sensor Networks

Topolgy control is one of the most important techniques used in wireless ad hoc and sensor networks to reduce energy consumption, which is essential to extend the network operational time. The goal of this technique is to control the topology of the graph representing the communication links between network nodes, with the purpose of maintaining some global graph theory (e.g., connectivity) while reducing energy consumption, which is strictly related to the nodes\u27 transmitting range

Comparison of a Cell-Based Energy Conservation Techniqueand MST Topology Control in Wireless Ad Hoc Networks

Cooperative strategies and topology control protocols have been recently proposed as effective techniques to reduce energy consumption in wireless ad hoc networks. Although these approaches share the same goal of extending network lifetime, they can be considered as orthogonal approaches

k-NEIGHLEV: a Practical Realization of Neighborhood-Based Topology Control in Ad Hoc Networks

Neighborhood-based topology control has been proven to be very effective in reducing energy consumption and increasing network capacity in ad hoc networks. In this paper, we present a practical realization of this approach that does not rely on distance estimation. Instead, the protocols presented in this paper leverage a feature typical of current wireless cards, namely that discrete power levels can be used for transmission. Ours are the first discrete-power-level protocols that do not require changing the power level on a per-packet basis. We demonstrate, through simulation, that the excellent performance of neighborhood-based topology control is maintained in this more practical setting. We also show that significant energy savings can be obtained if the power levels are optimized for topology control, rather than chosen in an ad hoc manner. Finally, we extend our approach to provide a neighborhood-based topology control protocol that is suitable for mobile networks

Topology design and scheduling in STDMA based wireless ad hoc networks

Cataloged from PDF version of article.With current advances in technology, wireless networks are increasing in popularity. Wireless networks allow users the freedom to travel from one location to another without interruption of their communication activities. Ad hoc networks, a subset of wireless networks, allow the formation of a wireless network without the need for a base station. Since no fixed infrastructure is involved in the communication, the nodes of ad hoc networks can communicate with each other or can relay data to other nodes. With this flexibility, wireless ad hoc networks have the ability to form a network anywhere, at any time, as long as two or more wireless users are willing to communicate. Managing ad hoc networks is a significantly more difficult task than managing wireline networks. The network requirements should be met by combined efforts of all the mobile nodes themselves. The nodes of ad hoc networks often operate under severe constraints, such as limited battery power, variable link quality and limited shared bandwidth. In this study, the topology design issue in ad hoc wireless networks is investigated. We employ hierarchical routing where the network topology is composed of clusters interconnected via a root node. Cluster-based topologies are suitable for military services, an important application area for ad hoc networks. The common power control technique (COMPOW) is used in this thesis where all nodes transmit at the same power level. Nodes employ the spatial TDMA (STDMA) scheme in order to access the channel. An important task is how to produce a minimum STDMA frame length, and this problem is known to be NP complete. We develop a heuristic algorithm for generating the minimum STDMA frame length. A new interference model for ad hoc networks is proposed which utilizes a hypergraph model. The relationship between the frame length, number of clusters and the transmit power level are investigated through numerical examples using a 15- node network.Ergin, Sadettin AlpM.S

A Performance Study of Proactive, Reactive and Hybrid Routing Protocols using Qualnet Simulator

The advancement in information technology and the need for large-scale communication infrastructures has triggered the era of Wireless Sensor Networks (WSNs). Mobile ad-hoc network (MANET) is a network of wireless mobile nodes which communicate with each other without any centralized control or established infrastructure. Routing is the process of selecting paths in a network along which data is to be sent. Routing is a critical task in MANET where the nodes are mobile. Dynamic and reliable routing protocols are required in the ad-hoc wireless networks, as they have no infrastructure (base station) and their network topology changes. There are various protocols for handling the routing problem in the ad-hoc wireless network environment. In this paper focus is given on studying the performance evaluation of various routing protocols using Qualnet simulator 5.0.2. The performance of the proactive, reactive and hybrid protocols are analyzed with different node densities for mobile and stationary nodes. The metrics used for the performance evaluation include average jitter, throughput, packet delivery ratio and average end to end delay