715 research outputs found

    Security and Privacy Issues in Wireless Mesh Networks: A Survey

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    This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

    Adapting mobile systems using logical mobility primitives

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    Mobile computing devices, such as personal digital assistants and mobile phones, are becoming increasingly popular, smaller, more capable and even fashionable personal items. Combined with the recent advent of wireless networking techniques, users are equipped with mobile devices of significant computational abilities, which are able to wirelessly access information by dynamically connecting to many different networks. Despite the ubiquity of mobile devices, mobile systems are built using monolithic architectures, use a small set of predefined interaction paradigms and do not exploit or adapt to the dynamicity of their local or remote context. Applications deployed on mobile devices face considerable challenges posed by their changing surroundings. One of the main peculiarities of mobile devices is heterogeneity, which may occur in software, hardware and network protocols. Mobile systems may carry a large number of different applications, use different operating systems and middleware and, often, have more than one network interface. A further challenge is their considerable variation in the computational resources available, such as battery power, CPU speed, network bandwidth and volatile and persistent memory. Moreover, mobile computing systems are highly dynamic systems, in terms of their surroundings, implying that the requirements for applications deployed on a mobile device are a moving target. Changes in the requirements (such as integration with a new service) may require changes to the application. Consequently, these changes may mean that the application behaviour needs to adapt. This thesis argues that the potential of the ubiquity of mobile devices cannot be realised using static and monolithic architectures, as mobile systems need to be able to adapt to accommodate changes to their environment. It investigates the use of three technologies to offer adaptation to mobile devices: Logical mobility techniques, component systems and middleware technologies. More specifically, this thesis presents the SATIN (System Adaptation Targeting Integrated Networks) component metamodel, a lightweight local component metamodel that offers the flexible use of logical mobility primitives. The metamodel is instantiated to build the SATIN middleware system, a component-based mobile computing middleware that uses the mobility primitives exported by the metamodel to reconfigure itself and applications running on top of it. The suitability of SATIN for the creation of adaptable mobile systems is demonstrated, by using it to implement and evaluate a number of applications showing different aspects of adaptation. Moreover, existing projects are reengineered to run as SATIN components, showing the flexibility of the approach and the advantages gained over the originals

    Predictive Analytics for Complex IoT Data Streams

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    EXPLAINING THE ROLE OF SERVICE-ORIENTED ARCHITECTURE FOR CYBER-PHYSICAL SYSTEMS BY ESTABLISHING LOGICAL LINKS

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    In the context of the so-called fourth industrial revolution, cyber-physical systems (CPS) build the technological foundation for the increasing digitalisation of our world. Because guidelines to overcome challenges of building such systems (e.g. security concerns, missing know-how, and lack of standards) are scarce, researchers and practitioners alike have begun to analyse the role of the mature paradigm of service-oriented architecture (SOA) in implementing CPS. However, the relationship between SOA and CPS is not entirely understood. To close this gap, we analyse SOA’s role for CPS based on a concept-driven literature review. The analysis of 12 publications that address the interrelation between SOA and CPS yielded four groups of CPS benefits that can be achieved by leveraging SOA. Combining these benefits with architectural layers and SOA’s design principles, we identify logical links that explain the role of SOA for CPS. Future research might concentrate on dominant patterns to scrutinise how a specific benefit can be achieved by leveraging SOA. Designers of CPS can leverage the identified patterns to understand the importance of specific characteristics of SOA to address the unique requirements of their CPS

    Context Sensor Data on Demand for Mobile Users Supported by XMPP

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    Tänapäeval võimaldavad tehnoloogilised edusammud kasutaja käitumise seiremeetodites automatiseerida teatud arvutusülesandeid, mis täidetakse kasutaja kavatsust prognoosides. Nutitelefonid rikastavad mobiilseid rakendusi prognoosiva käitumisega kasutatavuses, mis võimaldab käitumismustritega sammu pidada. Üldiselt on sellist käitumist võimalik saavutada nutitelefoni enda vahenditega, kasutades telefoni sisse ehitatud mikromehaanilisi seadmeid, mis võimaldavad keskkonda tajuda. Lisaks võivad mobiilsed rakendused kasutaja mobiilse kogemuse rikastamiseks lõigata kasu keskkonda integreeritud hajuslausteenustest, nagu näiteks ümbrustundlike mängude, kodu automatiseerimise tarkvara jms puhul. Ent mobiilikasutajatele suunatud lausteenuseid pakkuvatel elektroonilistel seadmetel, mis koguvad sensorite abi keskkonnast informatsiooni, on teatavad riistvaralised piirangud (arvutusjõudlus, mälu, salvestusmeedia, energiatarbimine jne). Seega, lausüsteemid ei ole võimelised nõudluse suurenemisel skaleeruma ega rakendama suurt arvutusjõudlust. Töö eesmärgiks on pakkuda lahendus ületamaks skaleeruvuse, andmete terviklikkuse säilitamise ja vähese arvutusjõudluse probleeme ning rikastada nutitelefoni rakendusi detailsete kasutajapõhiste andmetega. Eesmärgi saavutamiseks transporditakse sensoritelt kogutud informatsioon optimiseeritud XMPP protokolli abiga Arduino mikrokontrollerist pilvesüsteemi. Süsteemi ehitamiseks kasutatakse Arduino poolt pakutavat odavat riistvara, samas kui pilvesüsteemi usaldusväärset ja kõrge kättesaadavusega vahendeid kasutatakse mikrokontrollerist saadetud andmete salvestamiseks ja edaspidiseks töötlemiseks. Töö käigus testiti mikrokontrolleri energia nõudlust, kasutades 9V patareid, nii juhtme kui ka juhtmevaba liidesega. Tulemused tõestasid eeldustele vastupidiselt, et juhtmevaba süsteemi energia nõudlus on suurem. Lisaks testiti vabavara XMPP serveri jõudlust pilvesüsteemi keskkonnas ning tulemused näitasid, et XMPP võimaldab üheaegselt serveerida suure hulga kasutajaid

    Effective link quality estimation as a means to improved end-to-end packet delivery in high traffic mobile ad hoc networks

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    Accurate link quality estimation is a fundamental building block in quality aware multi hop routing. In an inherently lossy, unreliable and dynamic medium such as wireless, the task of accurate estimation becomes very challenging. Over the years ETX has been widely used as a reliable link quality estimation metric. However, more recently it has been established that under heavy traffic loads ETX performance gets significantly worse. We examine the ETX metric's behavior in detail with respect to the MAC layer and UDP data; and identify the causes of its unreliability. Motivated by the observations made in our analysis, we present the design and implementation of our link quality measurement metric xDDR – a variation of ETX. This article extends xDDR to support network mobility. Our experiments show that xDDR substantially outperforms minimum hop count, ETX and HETX in terms of end-to-end packet delivery ratio in static as well as mobile scenarios.</p
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