Wireless Mesh Networks (WMNs) built with commodity 802.11 radios are a cost-effective means of providing last mile broadband Internet access. Their multihop architecture allows for rapid deployment and organic growth of these networks. 802.11 radios are an important building block in WMNs. These low cost radios are readily available, and can be used globally in license-exempt frequency bands. However, the 802.11 Distributed Coordination Function (DCF) medium access mechanism does not scale well in large multihop networks. This produces suboptimal behavior in many transport protocols, including TCP, the dominant transport protocol in the Internet. In particular, cross-layer interaction between DCF and TCP results in flow level unfairness, including starvation, with backlogged traffic sources. Solutions found in the literature propose distributed source rate control algorithms to alleviate this problem. However, this requires MAC-layer or transport-layer changes on all mesh routers. This is often infeasible in practical deployments. In wireline networks, router-assisted rate control techniques have been proposed for use alongside end-to-end mechanisms. We evaluate the feasibility of establishing similar centralized control via gateway mesh routers in WMNs. We find that commonly used router-assisted flow control schemes designed for wired networks fail in WMNs. This is because they assume that: (1) links can be scheduled independently, and (2) router queue buildups are sufficient for detecting congestion. These abstractions do not hold in a wireless network, rendering wired scheduling algorithms such as Fair Queueing (and its variants) and Active Queue Management (AQM) techniques ineffective as a gateway-enforceable solution in a WMN. We show that only non-work-conserving rate-based scheduling can effectively enforce rate allocation via a single centralized traffic-aggregation point. In this context we propose, design, and evaluate a framework of centralized, measurement-based, feedback-driven mechanisms that can enforce a rate allocation policy objective for adaptive traffic streams in a WMN. In this dissertation we focus on fair rate allocation requirements. Our approach does not require any changes to individual mesh routers. Further, it uses existing data traffic as capacity probes, thus incurring a zero control traffic overhead. We propose two mechanisms based on this approach: aggregate rate control (ARC) and per-flow rate control (PFRC). ARC limits the aggregate capacity of a network to the sum of fair rates for a given set of flows. We show that the resulting rate allocation achieved by DCF is approximately max-min fair. PFRC allows us to exercise finer-grained control over the rate allocation process. We show how it can be used to achieve weighted flow rate fairness. We evaluate the performance of these mechanisms using simulations as well as implementation on a multihop wireless testbed. Our comparative analysis show that our mechanisms improve fairness indices by a factor of 2 to 3 when compared with networks without any rate limiting, and are approximately equivalent to results achieved with distributed source rate limiting mechanisms that require software modifications on all mesh routers.

Το έγγραφο είναι μια έρευνα του υποσυστήματος πολυμέσων διαδικτυακού πρωτοκόλλου και μια υλοποιήση ενός περιβάλλοντος προσομοίωσης, γνωστό ως testbed, που βασίζεται σε αυτό το πρωτόκολλο. Στην αρχή γίνεται μια εισαγωγή στην έννοια του IMS. Στο δεύτερο κεφάλαιο, περιγράφουμε τη γενική αρχιτεκτονική του IMS. Στο τρίτο κεφάλαιο, υπάρχει αναφορά στο επίπεδο σηματοδοσίας και όλα τα στοιχεία του. Στο τέταρτο κεφάλαιο περιγράφουμε τις υπηρεσίες που παρέχει το IMS και την αρχιτεκτονική του Open IMS Core που αποτελεί το περιβάλλον προσομοίωσής μας. Τέλος, αναλύουμε τα βήματα με σκοπό να εγκαταστήσουμε τον Open IMS Core ρησιμοποιώντας το λειτουργικό σύστημα Linux. / The script is a research of the Internet Protocol Multimedia Subsystem (IMS) and an implementation of a simulation environment, known as testbed and based on this protocol. In the beginning, there is an introduction to the meaning of IMS.In chapter two, we describe the general architecture of IMS. In chapter three, there is a reference to the signalling level and all of its elements. In chapter four we describe the services that IMS provides and the architecture of the Open IMS Core which is our simulation environment. Finally, we analyse the steps in order to install Open Ims Core using Linux operating system.

With the fast adoption of LTE and IEEE 802.11N, more devices are employing multiple antennas to boost the data rate and reliability of the communication link. Traditionally, fixed antennas are used in such devices. In recent years, reconfigurable antennas have been sought out to further boost the performance, which can adaptor to the changing wireless channel by altering their radiation characteristics, and maintain or exceed the performance of fixed antennas. This thesis studies the possibility of performance increase using pattern reconfigurable antennas as receivers. Their performance potential was first estimated using simulations, and then demonstrated using two electrically steerable passive array radiator (ESPAR) antennas against a pair of monopole antennas on a hardware bit error rate (BER) testbed. The former produces equal performance in BER with certain pattern combinations and excels in theoretical capacity with substantial lead making pattern reconfigurable antenna a potent option as receiver in MIMO-related applications.

With the fast adoption of LTE and IEEE 802.11N, more devices are employing multiple antennas to boost the data rate and reliability of the communication link. Traditionally, fixed antennas are used in such devices. In recent years, reconfigurable antennas have been sought out to further boost the performance, which can adaptor to the changing wireless channel by altering their radiation characteristics, and maintain or exceed the performance of fixed antennas. This thesis studies the possibility of performance increase using pattern reconfigurable antennas as receivers. Their performance potential was first estimated using simulations, and then demonstrated using two electrically steerable passive array radiator (ESPAR) antennas against a pair of monopole antennas on a hardware bit error rate (BER) testbed. The former produces equal performance in BER with certain pattern combinations and excels in theoretical capacity with substantial lead making pattern reconfigurable antenna a potent option as receiver in MIMO-related applications.

Orientador: Alexandre Cezar Rodrigues da Silva / Resumo: A simulação de ambientes computacionais é uma das principais técnicas para estudo de protocolos, seu comportamento em redes de computadores e análise da segurança da informação. O acesso a ambientes reais para simulação de smart grids está restrito a poucas universidades e empresas assim como existem poucas ferramentas disponíveis para sua simulação computacional, o que dificulta a realização de pesquisas nesta linha. Neste trabalho objetiva-se a configuração de um ambiente para simulação do protocolo DNP3 utilizando exclusivamente ferramentas open source, utilizando-se técnicas de segurança ofensiva para realizar ataques a rede e então validar o comportamento da simulação e por fim realizar a integração do ambiente de simulação com equipamentos reais. Para isso, foi desenvolvido um testbed virtual através da integração e configuração de diversas ferramentas e softwares open source e posteriormente utilizados os equipamentos do Laboratório de Proteção do Campus III na UNESP de Ilha Solteira, expandindo as funcionalidades do simulador e obtendo um testbed misto com resultados promissores em todos os testes realizados. / Mestre

abstract: This thesis describes a synthetic task environment, CyberCog, created for the purposes of 1) understanding and measuring individual and team situation awareness in the context of a cyber security defense task and 2) providing a context for evaluating algorithms, visualizations, and other interventions that are intended to improve cyber situation awareness. CyberCog provides an interactive environment for conducting human-in-loop experiments in which the participants of the experiment perform the tasks of a cyber security defense analyst in response to a cyber-attack scenario. CyberCog generates the necessary performance measures and interaction logs needed for measuring individual and team cyber situation awareness. Moreover, the CyberCog environment provides good experimental control for conducting effective situation awareness studies while retaining realism in the scenario and in the tasks performed. / Dissertation/Thesis / M.C.St. Computing Studies 2011

Wireless sensor networks (WSNs) have been used in many applications by deploying tiny and stationary sensors. In recent years, a lot of studies proposed to introduce mobility capability to sensor nodes in order to exploit the advantages of mobility, particularly to restore connectivity in disjoint WSNs. While the studies demonstrated various capabilities of the proposed connectivity algorithms via simulation, real node and testbed implementations were mostly lacking due to unavailability of proper mobile nodes. Since this may hinder the direct applicability of the algorithms in realistic settings, testbeds which can be constructed with low-cost and commercial-off-the-shelf (COTS) hardware are required for realistic evaluations of the connectivity restoration algorithms. In this thesis, we design a low-cost mobile sensor node called iRobotSense, by integrating iRobot Create platform with IRIS sensor. Then, a mobile sensor network (MSN) testbed of iRobotSense nodes is used to implement and evaluate a widely used connectivity restoration algorithms, namely PADRA. Furthermore, all of the previous works exploiting mobility of the nodes to achieve recovery in a partitioned network have assumed reachability of the nodes to the selected destinations via a direct path movement. However, in real-world applications, such assumption makes the schemes impractical in case of encountering obstacles or intolerable terrains. Besides, even if direct path movement is successful, optimal energy efficiency cannot be attained by neglecting the elevation or friction of the terrain. Thus, in the recovery efforts, terrain type, elevation as well as the obstacles should be taken into account. In this thesis, we re-design an existing connectivity restoration approach in disjoint MSNs to fit these requirements and evaluate the performance issues when realistic terrains are assumed. Rather than following a direct path, movement trajectory is determined based on a path planning algorithm which considers the risk and elevation of terrain sections to be visited while avoiding obstacles and highly elevated terrain sections.

Smart Cyber-Physical Systems (sCPS) are complex systems performing smart coordination that often require decentralized and network resilient operation. New development in the fields of the robotic systems, Industry 4.0 and autonomous vehicular system brings challenges that can be tackled with deployment of ensemble based sCPS, but require further refinement in terms of network resilience and data propagation. This thesis maps the use cases of the sCPS in the aforementioned domains, discusses requirements on the ensemble based architecture in terms of network properties, and proposes recommendations and technical means that help to design network aware ensemble based sCPS. The proposed solutions are evaluated by the means of target systems simulation using state of the art realistic network and vehicular simulators.

Submitted by ANDRÉ LUIZ LATANSIO DE OLIVEIRA null (andrelatansio@gmail.com) on 2017-08-03T12:48:20Z No. of bitstreams: 1 dissertacao_final_submeter.pdf: 6036596 bytes, checksum: debf9708c542db4157e83657c0859084 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-08-03T17:52:18Z (GMT) No. of bitstreams: 1 oliveira_all_me_ilha.pdf: 6036596 bytes, checksum: debf9708c542db4157e83657c0859084 (MD5) / Made available in DSpace on 2017-08-03T17:52:18Z (GMT). No. of bitstreams: 1 oliveira_all_me_ilha.pdf: 6036596 bytes, checksum: debf9708c542db4157e83657c0859084 (MD5) Previous issue date: 2017-07-07 / A simulação de ambientes computacionais é uma das principais técnicas para estudo de protocolos, seu comportamento em redes de computadores e análise da segurança da informação. O acesso a ambientes reais para simulação de smart grids está restrito a poucas universidades e empresas assim como existem poucas ferramentas disponíveis para sua simulação computacional, o que dificulta a realização de pesquisas nesta linha. Neste trabalho objetiva-se a configuração de um ambiente para simulação do protocolo DNP3 utilizando exclusivamente ferramentas open source, utilizando-se técnicas de segurança ofensiva para realizar ataques a rede e então validar o comportamento da simulação e por fim realizar a integração do ambiente de simulação com equipamentos reais. Para isso, foi desenvolvido um testbed virtual através da integração e configuração de diversas ferramentas e softwares open source e posteriormente utilizados os equipamentos do Laboratório de Proteção do Campus III na UNESP de Ilha Solteira, expandindo as funcionalidades do simulador e obtendo um testbed misto com resultados promissores em todos os testes realizados. / The simulation of computational environments is one of the main techniques applied in the study of protocols, the behavior of those protocols in computer networks, and the analysis of information security procedures. Research in the area of smart grid simulation is hampered by the fact that few universities and companies have access to real environments, and further, that the number of computational tools available is limited. This paper therefore aims to configure an environment for the simulation of the DNP3 protocol using exclusively open source tools and by applying offensive security techniques including attacks which seek to exploit network vulnerabilities; subsequently, the proposed simulation behavior is validated. For this purpose, a virtual testbed was developed by integrating and configuring various open source software and tools and later using the Campus III Protection Laboratory equipments at UNESP Ilha Solteira, expanding the simulator functionalities and obtaining a mixed testbed with results promising in all tests performed.

As the vision of the Internet of Things (IoT) becomes a reality, thousands of devices will beconnected to IoT platforms in smart cities and regions. These devices will actively send dataupdates to cloud-based platforms, as part of smart applications in domains like healthcare, trafficand pollution monitoring. Therefore, it is important to study the ability of modern IoT systemsto handle high rates of data updates coming from devices. In this work we evaluated the per-formance of components of the Internet of Things Services Enablement Architecture of theEuropean initiative FIWARE. We developed a testbed that is able to inject data updates usingMQTT and the CoAP-based Lightweight M2M protocols, simulating large scale IoT deploy-ments. Our extensive tests considered the vertical and horizontal scalability of the componentsof the platform. Our results found the limits of the components when handling the load, and thescaling strategies that should be targeted by implementers. We found that vertical scaling is notan effective strategy in comparison to the gains achieved by horizontally scaling the databaselayer. We reflect about the load testing methodology for IoT systems, the scalability needs ofdifferent layers and conclude with future challenges in this topic.