In dieser Arbeit werden P2P-Algorithmen in ressourcen-limitierten und irregulären Wireless-ad-hoc-Netzwerken (WAHN) betrachtet, die effizient, skalierbar und fehlertolerant in Situationen arbeiten sollen, in denen eine räumlich benachbarte Gruppe von Netzwerkknoten simultan ausfällt. Es wird ein fehlertolerantes Replikationsschema zur datenzentrischen Speicherung betrachtet, und eine selbstorganisierende, skalierbare Berechnung von Datenaggregaten zur Lösung des Konsensproblems. Existierende P2P-Algorithmen die Skalierbarkeit, Fehlertoleranz und Selbstorganisation in drahtgebundenen Netzen betrachten sind für die Klasse des WAHNs nicht geeignet weil sie Engpässe in WAHNs verursachen können und in Katastrophenmanagement-szenarien die Zuverlässigkeit der Daten nicht sicherstellen können. Die Verwendung von Informationen der geographischen Position von Knoten ist ein möglicher Weg, um die Effizienz und Skalierbarkeit von P2P-Anwendungen in drahtlosen Netzwerken zu verbessern. In dieser Arbeit wird ein neuer Ansatz vorgestellt, wie auf effiziente Weise 1) Gebiet des Netzwerks, das die geographische Ausbreitung seiner Knoten umfasst, und 2) Gruppenzugehörigkeit, wobei jeder Knoten zu genau einer Gruppe innerhalb eines einstellbaren Gebietes gehört, erzeugt werden kann. Dadurch können: existierenden, skalierbare P2P Datenspeicheralgorithmen für WAHNs genutzt werden, effiziente, fehlertolerante Replikation erstellt werden, die Effizienz von geographischen Routing und der Suche nach Replikaten verbessert werden sowie, Anwendungen auf einen bestimmten geographischen Bereich innerhalb des WAHN beschränkt werden (z.B. im Aggregationsprotokoll). Die entwickelten Protokolle sind tolerant gegenüber Nachrichtenverlust und verwenden ausschließlich lokale Broadcast-Nachrichten. Das Protokoll wurde mit Simulationen untersucht, die auf realistischen Netzwerktopologien mit Anteilen an sehr spärlichen und sehr dichten Knotenansammlungen basieren. / This dissertation addresses the challenge of reaching efficiency, scalability and fault-tolerance by P2P algorithms for resource-limited and irregular wireless ad-hoc networks (WAHNs) in disaster management (DM) scenarios where a spatially correlated group of nodes may crash simultaneously. In particular, we consider a fault-tolerant replication scheme for data-centric storage and a self-organized, scalable calculation of localized data aggregates for solving the consensus problem. Existing Peer-to-Peer algorithms that address issues of scalability, fault tolerance and self-organization in wired networks are inadequate for the addressed systems, they may cause bottlenecks in WAHNs and use replication that abstracts from geographical location of replicas and cannot therefore supply data survivability in DM scenarios in WAHNs. Incorporating information on geographical location of nodes is a recognized way to increase the efficiency and scalability of P2P applications in wireless networks. This dissertation proposes to efficiently construct new position information in a location-aware WAHN, where each node knows its own location and location of its direct neighbors. The new information are: network area, which expresses the geographical area covered by the network, and group membership, where each node belongs to exactly one group that is placed over the area of a maximum defined size. Together, they enable the use of the existing, scalable P2P data store in WAHNs (Geographical Hash Table), allow design of efficient fault-tolerant replication for the assumed fault model, increase efficiency of geographic routing and replica search, and allow to limit the geographical extent of activity of any distributed application, as we show using an example of data aggregation protocol. Proposed protocols tolerate message loss and use local broadcast only. They are evaluated by simulation over irregular topologies following the node placement of the existing, large WAHNs.

<p>A <i>wireless ad hoc network </i>consists of a number of mobile nodes that temporarily form a dynamic infrastructure-less network. New routing protocols that can adapt to the frequent topology changes induced by node mobility and varying link qualities are needed. During the last decade dozens of different ad hoc routing protocols have been proposed, optimized and partially compared, mainly through simulation studies.</p><p>This thesis takes an experimental approach to the evaluation of ad hoc routing protocols. We argue that real world experiments are needed in order to complement simulation studies, and to gain practical experience and insights that can provide feedback to routing protocol design and existing simulation models. For example, we discovered a performance discrepancy for the AODV protocol between real world experiments and corresponding simulation studies. This so called ``communication gray zone'' problem was explored and countermeasures were implemented. As a result we could eliminate this performance problem to a large extent. </p><p>We have implemented a software-based testbed called APE to carry out efficient and systematic experimental evaluation of ad hoc routing protocols. Experiments with up to 37 participating ad hoc nodes have demonstrated APE's ability to scale efficiently and assess repeatability between test runs. APE is part of our methodology for test repeatability in a real world ad hoc routing protocol testbed. It addresses the repeatability issue induced by stochastic factors like the radio environment and node mobility. Using APE, we have performed a systematic experimental evaluation of three ad hoc routing protocols (AODV, OLSR and LUNAR). Our results show that TCP does not work satisfactorily even in very small networks with limited mobility.</p>

A Mobile Ad Hoc Network (MANETs) is a collection of wireless hosts that can be rapidly deployed as a multi hop packet radio network without the aid of any established infrastructure or centralized administration. Such networks can be used to enable next generation of battlefield applications envisioned by the military, including situation awareness systems for maneuvering war fighters, and remotely deployed unmanned microsensor networks. Ad Hoc networks can also provide solutions for civilian applications such as disaster recovery and message exchanges among safety and security personnel involved in rescue missions. Existing solutions for wired network Intrusion Detection Systems (IDSs) do not suit wireless Ad Hoc networks. To utilize either misuse detection or anomaly detection to monitor any possible compromises, the IDS must be able to distinguish normal from anomaly activities. To enable intrusion detection in wireless Ad Hoc networks, the research problems are: • How to efficiently collect normal and anomaly patterns of Ad Hoc networks? The lifetime of the hosts is short and Ad Hoc networks do not have traffic concentration points (router, switch). • How to detect anomalies? The loss could be caused by host movement instead of attacks. Unexpectedly long delay could be caused by unreliable channel instead of malicious discard. In this thesis, we have proposed a novel architecture that uses specification based intrusion detection techniques to detect active attacks against the routing protocols of mobile Ad Hoc networks. Our work analyzes some of the vulnerabilities and discuss the attacks against the AODV protocol. Our approach involves the use of an FSM (Finite State Machine) for specifying the AODV routing behavior and the distributed network monitors for detecting the sequence number attack. Our method can detect most of the bad nodes with low false positive rate and the packet delivery ratio can also be increased with high detection rate. For packet dropping attack, we present a distributed technique to detect this attack in wireless Ad Hoc networks. A bad node can forward packets but in fact it fails to do so. In our technique, every node in the network will check the neighboring nodes to detect if any of them fail to forward the packets. Our technique can detect most of the bad nodes with low false positive rate and the packet delivery ratio can also be increased. The proposed solution can be applied to identify multiple malicious nodes cooperating with each other in MANETs and discover secure routes from source to destination by avoiding malicious nodes acting in cooperation. Our technique will detect the sequence number and Packet Dropping attacks in real time within its radio range with no extra overhead. For resource consumption attack, the proposed scheme incurs no extra overhead, as it makes minimal modifications to the existing data structures and functions related to bad listing a node in the existing version of pure AODV. The proposed scheme is more efficient in terms of the resultant routes established, resource reservations, and computational complexity. If multiple malicious nodes collaborate, they in turn will be restricted and isolated by their neighbors, because they monitor and exercise control over forwarding RREQs by nodes. Hence, the scheme successfully prevents Distributed attacks. The proposed scheme shifts the responsibility of monitoring this parameter to the node's neighbor, ensuring compliance of this restriction. This technique solves all of the problems caused due to unnecessary RREQs from a compromised node. Instead of self-control, the control exercised by a node's neighbor results in preventing this attack. Experiments show that the tool provides effective intrusion detection functionality while using only a limited amount of resources. The loop freedom property has been reduced to an invariant on pairs of nodes. Each node decides & transmits its decision to a control center. Robustness to Threats, Robustness to nodes destruction: Loss of Performance (in terms of ratio) is least for Distributed Option and highest for Centralized Option and Robustness to observations deletion. All the proposed schemes were analyzed and tested under different topologies and conditions with varying number of nodes .The proposed algorithms for improving the robustness of the wireless Ad Hoc networks using AODV protocol against Packet Dropping Attack, Sequence Number attack and resource consumption attack have been simulated for an illustrative network of about 30 nodes. Our experiments have shown that the pattern extracted through simulation can be used to detect attacks effectively. The patterns could also be applied to detect similar attacks on other protocols.

Mobility-Based Routing Overhead Management in Reconfigurable Wireless Ad Hoc Networks Routing Overheads are the non-data message packets whose roles are establishment and maintenance of routes for data packets as well as neighbourhood discovery and maintenance. They have to be broadcasted in the network either through flooding or other techniques that can ensure that a path exists before data packets can be sent to various destinations. They can be sent reactively or periodically to neighbours so as to keep nodes updated on their neighbourhoods. While we cannot do without these overhead packets, they occupy much of the limited wireless bandwidth available in wireless networks. In a reconfigurable wireless ad hoc network scenario, these packets have more negative effects, as links need to be confirmed more frequently than in traditional networks mainly because of the unpredictable behaviour of the ad hoc networks. We therefore need suitable algorithms that will manage these overheads so as to allow data packet to have more access to the wireless medium, save node energy for longer life of the network, increased efficiency, and scalability. Various protocols have been suggested in the research area. They mostly address routing overheads for suitability of particular protocols leading to lack of standardisation and inapplicability to other protocol classes. In this dissertation ways of ensuring that the routing overheads are kept low are investigated. The issue is addressed both at node and network levels with a common goal of improving efficiency and performance of ad hoc networks without dedicating ourselves to a particular class of routing protocol. At node level, a method hereby referred to as &amp;quot;link availability forecast&amp;quot;, that minimises routing overheads used for maintenance of neighbourhood, is derived. The targeted packets are packets that are broadcasted periodically (e.g. hello messages). The basic idea in this method is collection of mobility parameters from the neighbours and predictions or forecasts of these parameters in future. Using these parameters in simple calculations helps in identifying link availabilities between nodes participating in maintenance of networks backbone. At the network level, various approaches have been suggested. The first approach is the cone flooding method that broadcasts route request messages through a predetermined cone shaped region. This region is determined through computation using last known mobility parameters of the destination. Another approach is what is hereby referred as &amp;quot;destination search reverse zone method&amp;quot;. In this method, a node will keep routes to destinations for a long time and use these routes for tracing the destination. The destination will then initiate route search in a reverse manner, whereby the source selects the best route for next delivery. A modification to this method is for the source node to determine the zone of route search and define the boundaries within which the packet should be broadcasted. The later method has been used for simulation purposes. The protocol used for verification of the improvements offered by the schemes was the AODV. The link availability forecast scheme was implemented on the AODV and labelled AODV_LA while the network level implementation was labelled AODV_RO. A combination of the two schemes was labelled AODV_LARO.

在未來的無線點對點環境中，由於資訊將被賦予金錢上的價值，故核心議題將不在於如何解決資訊便車者問題，而是必須針對有價資訊制定一有效的定價模式以促進個體提供差異化服務的意願。本研究所提出之情境式小額定價模式，以價值導向定價為基礎，除了針對個體本身資源限制考量而設計之外，更考量服務本身之特性(如無形性、不可分割性、異質性與易逝性)，因此可有效地針對個體目前所處的情境需求以協助服務買方與賣方分別制定服務價格策略與價格談判策略，讓買賣雙方可快速地達成協議。 本研究期望藉由情境式定價與談判機制的提出，能對WP2P 的無線應用服 務發展有所貢獻，並期望讓使用者在動態且即時的環境下，能有效地促進資訊分享的意願與流通，進而能恣意地享受行動服務所帶來的全新生活體驗。 / In the foreseeable Wireless Peer-to-Peer (WP2P) environments (in which information traded is associated with monetary value), one of the key issues in WP2P will focus on how to build efficient pricing strategies to facilitate the peers’ willingness of offering differentiated services (rather than the status–quo of merely resolving the free rider problems). Accordingly, this paper presents a contextualized micro pricing strategy for e-services operating in distributed WP2P environments. The pricing strategy grounding in the concept of value-based pricing not only takes mobile device restrictions and attributes of the surrounding context (ex. time, location) into account, but also regards the unique features of services (intangibility, inseparability, heterogeneity, perishability) to assist service buyers and sellers to rapidly come to a deal with each other in terms of a lightweight pricing/bargaining process. The contribution of the proposed contextualized micro pricing strategy is to improve peers’ willingness of furnishing differentiated services and to enhance the distribution of the service resources amid the WP2P environments.

Orientador: Michel Daoud Yacoub / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-10T09:17:00Z (GMT). No. of bitstreams: 1 Medeiros_AlvaroAugustoMachadode_D.pdf: 910419 bytes, checksum: 8fee720ee964b6908659ff1ab27c754e (MD5) Previous issue date: 2007 / Resumo: As redes ad hoc são redes sem um controle centralizado, cujos nós se comunicam através de um canal sem fio diretamente ou através de múltiplos saltos. Uma questão complexa referente a redes ad hoc é o cálculo da capacidade. Estimar quantas transmissões a rede permite, garantindo qualidade de serviço aos usuarios é uma tarefa difícil em virtude de duas características da rede: o canal sem fio e as transmissões em múltiplos saltos. Este trabalho propõe um novo método para cálculo da capacidade através da probabilidade de outage que considera ambos os aspectos. Este método apresenta vantagens como fácil implantação, baixo esforço computacional e resultados praticamente indistinguíveis daqueles obtidos atraves de simulação. O metodo pode ser aplicado aos mais variados ambientes de propagação e qualquer topologia de rede. Modelos de interferência mais realistas, bem como a questão do roteamento são também abordados ao longo do trabalho / Abstract: Ad hoc networks are networks that operate without centralized control, whose nodes communicate through wireless links in a single or multihop way. A complex issue about ad hoc networks is the capacity estimation. The computation of how many transmissions the network can support ensuring a quality of service for its users is a difficult task due to two central aspects: the wireless medium and the multihop nature of transmissions. An analytical method to calculate the capacity through the computation of the outage probability considering both aspects is proposed in this work. This method presents advantages such as simple implementation, low computational efforts and practically indistinguishable results from those obtained through simulation. This method can be applied to many propagation environments and to any network topology. More realistic interference models and the routing issue are also described along this work / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

Mobility-Based Routing Overhead Management in Reconfigurable Wireless Ad Hoc Networks Routing Overheads are the non-data message packets whose roles are establishment and maintenance of routes for data packets as well as neighbourhood discovery and maintenance. They have to be broadcasted in the network either through flooding or other techniques that can ensure that a path exists before data packets can be sent to various destinations. They can be sent reactively or periodically to neighbours so as to keep nodes updated on their neighbourhoods. While we cannot do without these overhead packets, they occupy much of the limited wireless bandwidth available in wireless networks. In a reconfigurable wireless ad hoc network scenario, these packets have more negative effects, as links need to be confirmed more frequently than in traditional networks mainly because of the unpredictable behaviour of the ad hoc networks. We therefore need suitable algorithms that will manage these overheads so as to allow data packet to have more access to the wireless medium, save node energy for longer life of the network, increased efficiency, and scalability. Various protocols have been suggested in the research area. They mostly address routing overheads for suitability of particular protocols leading to lack of standardisation and inapplicability to other protocol classes. In this dissertation ways of ensuring that the routing overheads are kept low are investigated. The issue is addressed both at node and network levels with a common goal of improving efficiency and performance of ad hoc networks without dedicating ourselves to a particular class of routing protocol. At node level, a method hereby referred to as &amp;quot;link availability forecast&amp;quot;, that minimises routing overheads used for maintenance of neighbourhood, is derived. The targeted packets are packets that are broadcasted periodically (e.g. hello messages). The basic idea in this method is collection of mobility parameters from the neighbours and predictions or forecasts of these parameters in future. Using these parameters in simple calculations helps in identifying link availabilities between nodes participating in maintenance of networks backbone. At the network level, various approaches have been suggested. The first approach is the cone flooding method that broadcasts route request messages through a predetermined cone shaped region. This region is determined through computation using last known mobility parameters of the destination. Another approach is what is hereby referred as &amp;quot;destination search reverse zone method&amp;quot;. In this method, a node will keep routes to destinations for a long time and use these routes for tracing the destination. The destination will then initiate route search in a reverse manner, whereby the source selects the best route for next delivery. A modification to this method is for the source node to determine the zone of route search and define the boundaries within which the packet should be broadcasted. The later method has been used for simulation purposes. The protocol used for verification of the improvements offered by the schemes was the AODV. The link availability forecast scheme was implemented on the AODV and labelled AODV_LA while the network level implementation was labelled AODV_RO. A combination of the two schemes was labelled AODV_LARO.

No description available.

No / Security mechanisms, such as encryption and authentication protocols, require extra computing resources and therefore, have an adverse effect upon the performance of robotic mobile wireless ad hoc networks (RANETs). Thus, an optimal performance and security trade-off should be one of the main aspects that should be taken into consideration during the design, development, tuning and upgrading of such networks. In this context, an exposition is initially undertaken on the applicability of Petri nets (PNs) and queueing networks (QNs) in conjunction with their generalisations and hybrid integrations as robust quantitative modelling tools for the performance analysis of discrete flow systems, such as computer systems, communication networks and manufacturing systems. To overcome some of the inherent limitations of these models, a novel hybrid modelling framework is explored for the quantitative evaluation of RANETs, where each robotic node is represented by an abstract open hybrid G-GSPN_QN model with head-of-line priorities, subject to combined performance and security metrics (CPSMs). The proposed model focuses on security processing and state-based control and it is based on an open generalised stochastic PN (GSPN) with a gated multi-class 'On-Off' traffic and mobility model. Moreover, it employs a power consumption model and is linked in tandem with an arbitrary QN consisting of finite capacity channel queues with blocking for 'intra' robot component-to-component communication and 'inter' robot-to-robot transmission. Conclusions and future research directions are included.

Benefiting from the constant and significant advancement of wireless communication technologies and networking protocols, Wireless Ad hoc NETwork (WANET) has played a more and more important role in modern communication networks without relying much on existing infrastructures. The past decades have seen numerous applications adopting ad hoc networks for service provisioning. For example, Wireless Sensor Network (WSN) can be widely deployed for environment monitoring and object tracking by utilizing low-cost, low-power and multi-function sensor nodes. To realize such applications, the design and evaluation of communication protocols are of significant importance. Meanwhile, the network performance analysis based on mathematical models is also in great need of development and improvement. This dissertation investigates the above topics from three important and fundamental aspects, including data collection protocol design, protocol modeling and analysis, and physical interference modeling and analysis. The contributions of this dissertation are four-fold. First, this dissertation investigates the synchronization issue in the duty-cycled, pipelined-scheduling data collection of a WSN, based on which a pipelined data collection protocol, called PDC, is proposed. PDC takes into account both the pipelined data collection and the underlying schedule synchronization over duty-cycled radios practically and comprehensively. It integrates all its components in a natural and seamless way to simplify the protocol implementation and to achieve a high energy efficiency and low packet delivery latency. Based on PDC, an Adaptive Data Collection (ADC) protocol is further proposed to achieve dynamic duty-cycling and free addressing, which can improve network heterogeneity, load adaptivity, and energy efficiency. Both PDC and ADC have been implemented in a pioneer open-source operating system for the Internet of Things, and evaluated through a testbed built based on two hardware platforms, as well as through emulations. Second, Linear Sensor Network (LSN) has attracted increasing attention due to the vast requirements on the monitoring and surveillance of a structure or area with a linear topology. Being aware that, for LSN, there is few work on the network modeling and analysis based on a duty-cycled MAC protocol, this dissertation proposes a framework for modeling and analyzing a class of duty-cycled, multi-hop data collection protocols for LSNs. With the model, the dissertation thoroughly investigates the PDC performance in an LSN, considering both saturated and unsaturated scenarios, with and without retransmission. Extensive OPNET simulations have been carried out to validate the accuracy of the model. Third, in the design and modeling of PDC above, the transmission and interference ranges are defined for successful communications between a pair of nodes. It does not consider the cumulative interference from the transmitters which are out of the contention range of a receiver. Since most performance metrics in wireless networks, such as outage probability, link capacity, etc., are nonlinear functions of the distances among communicating, relaying, and interfering nodes, a physical interference model based on distance is definitely needed in quantifying these metrics. Such quantifications eventually involve the Nodal Distance Distribution (NDD) intrinsically depending on network coverage and nodal spatial distribution. By extending a tool in integral geometry and using decomposition and recursion, this dissertation proposes a systematic and algorithmic approach to obtaining the NDD between two nodes which are uniformly distributed at random in an arbitrarily-shaped network. Fourth, with the proposed approach to NDDs, the dissertation presents a physical interference model framework to analyze the cumulative interference and link outage probability for an LSN running the PDC protocol. The framework is further applied to analyze 2D networks, i.e., ad hoc Device-to-Device (D2D) communications underlaying cellular networks, where the cumulative interference and link outage probabilities for both cellular and D2D communications are thoroughly investigated. / Graduate / 0984 / 0544 / tong1987fei@163.com