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  • 451.
    Cambazoglu, Volkan
    Uppsala universitet, Avdelningen för datorteknik.
    Protocol, mobility and adversary models for the verification of security2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increasing heterogeneity of communicating devices, ranging from resource constrained battery driven sensor nodes to multi-core processor computers, challenges protocol design. We examine security and privacy protocols with respect to exterior factors such as users, adversaries, and computing and communication resources; and also interior factors such as the operations, the interactions and the parameters of a protocol.

    Users and adversaries interact with security and privacy protocols, and even affect the outcome of the protocols. We propose user mobility and adversary models to examine how the location privacy of users is affected when they move relative to each other in specific patterns while adversaries with varying strengths try to identify the users based on their historical locations. The location privacy of the users are simulated with the support of the K-Anonymity protection mechanism, the Distortion-based metric, and our models of users' mobility patterns and adversaries' knowledge about users.

    Security and privacy protocols need to operate on various computing and communication resources. Some of these protocols can be adjusted for different situations by changing parameters. A common example is to use longer secret keys in encryption for stronger security. We experiment with the trade-off between the security and the performance of the Fiat–Shamir identification protocol. We pipeline the protocol to increase its utilisation as the communication delay outweighs the computation.

    A mathematical specification based on a formal method leads to a strong proof of security. We use three formal languages with their tool supports in order to model and verify the Secure Hierarchical In-Network Aggregation (SHIA) protocol for Wireless Sensor Networks (WSNs). The three formal languages specialise on cryptographic operations, distributed systems and mobile processes. Finding an appropriate level of abstraction to represent the essential features of the protocol in three formal languages was central.

  • 452.
    Cambazoglu, Volkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Gutkovas, Ramunas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Åman Pohjola, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Victor, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Modelling and analysing a WSN secure aggregation protocol: A comparison of languages and tool support2015Report (Other academic)
  • 453.
    Cambazoglu, Volkan
    et al.
    Uppsala universitet, Datorarkitektur och datorkommunikation.
    Gutkovas, Ramunas
    Uppsala universitet, Datalogi.
    Åman Pohjola, Johannes
    Uppsala universitet, Datalogi.
    Victor, Björn
    Uppsala universitet, Datalogi.
    Modelling and analysing a WSN secure aggregation protocol: A comparison of languages and tool support2015Report (Other academic)
    Abstract [en]

    A security protocol promises protection of a significant piece of information while using it for a specific purpose. Here, the protection of the information is vital and a formal verification of the protocol is an essential step towards guaranteeing this protection. In this work, we study a secure aggregation protocol (SHIA) for Wireless Sensor Networks and verify the protocol in three formal modelling tools (Pwb, mCRL2 and ProVerif). The results of formal verification heavily depend on the model specification and the ability of the tools to deal with the model. Among the three tools, there is difference in data representation, communication types and the level of abstraction in order to represent SHIA. ProVerif and mCRL2 are mature and well-established tools, geared respectively towards security and distributed systems; however, their expressiveness constrains modelling SHIA and its security properties. Pwb is an experimental tool developed by the authors; its relative immaturity is offset by its increased expressive power and customisability. This leads to different models of the same protocol, each contributing in different ways to our understanding of SHIA's security properties.

  • 454.
    Campolo, Claudia
    et al.
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Koucheryavy, Yevgeni
    Department of Communications Engineering, Tampere University of Technology, Tampere, Finland.
    Molinaro, Antonella
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Vinel, Alexey
    Department of Communications Engineering, Tampere University of Technology, Tampere, Finland.
    Characterizing broadcast packet losses in IEEE 802.11p/WAVE vehicular networks2011Conference paper (Refereed)
  • 455.
    Campolo, Claudia
    et al.
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Koucheryavy, Yevgeni
    Department of Communications Engineering, Tampere University of Technology, Tampere, Finland.
    Molinaro, Antonella
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Vinel, Alexey
    Department of Communications Engineering, Tampere University of Technology, Tampere, Finland.
    On the Performance of Beaconing in 802.11p/WAVE Vehicular Ad Hoc Networks2010Conference paper (Refereed)
    Abstract [en]

    Cooperative vehicular applications, like collision avoidance, driver assistance, and cruise control require that vehicles become aware of other vehicles in the surroundings. This cooperative awareness is achieved by beaconing, the exchange of periodical single-hop broadcast short status message that include data about the position, the speed, and the heading of a vehicle. Although several works have studied beaconing techniques both from an analytical point of view and through simulative study, none of the existing works has investigated how beaconing works on top of 802.11p/WAVE (Wireless Access for Vehicular Environment), the upcoming standard intended to deliver both safety and non-safety applications to vehicles on the roads. According to it, safety and control messages are expected to be delivered on a given frequency during a common control channel (CCH) interval set by the WAVE draft standard. The rest of the time, vehicles switch over one of available service channel (SCH) frequencies for non-safety related data exchange. In this paper we discuss and evaluate through numerical results the main effects the WAVE channel switching procedures have on beaconing. © 2010 by IEICE

  • 456.
    Campolo, Claudia
    et al.
    Mediterranea University of Reggio Calabria, Reggio Calabria, Italy.
    Molinaro, Antonella
    Mediterranea University of Reggio Calabria, Reggio Calabria, Italy.
    Berthet, Antoine O.
    Gif-sur-Yvette, CNRS-Centrale Supélec-Université Paris Sud, Gif-sur-Yvette, France.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Full-Duplex Radios for Vehicular Communications2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 6, p. 182-189Article in journal (Refereed)
    Abstract [en]

    Recent significant advances in self-interference cancellation techniques pave the way for the deployment of full-duplex wireless transceivers capable of concurrent transmission and reception on the same channel. Despite the promise to theoretically double the spectrum efficiency, full-duplex prototyping in off-the-shelf chips of mobile devices is still in its infancy, mainly because of the challenges in mitigating self-interference to a tolerable level and the strict hardware constraints. In this article, we argue in favor of embedding full-duplex radios in onboard units of future vehicles. Unlike the majority of mobile devices, vehicular onboard units are good candidates to host complex FD transceivers because of their virtually unlimited power supply and processing capacity. Taking into account the effect of imperfect SI cancellation, we investigate the design implications of full-duplex devices at the higher-layer protocols of next-generation vehicular networks and highlight the benefits they could bring with respect to half-duplex devices in some representative use cases. Early results are also provided that give insight into the impact of self-interference cancellation on vehicle-to-roadside communications, and showcase the benefits of FD-enhanced medium access control protocols for vehicle-to-vehicle communications supporting crucial road safety applications.

  • 457.
    Campolo, Claudia
    et al.
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Molinaro, Antonella
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    To switch or not to switch: Service discovery and provisioning in multi-radio V2R communications2016In: Proceedings of 2016 8th International Workshop on Resilient Networks Design and Modeling (RNDM) / [ed] Magnus Jonsson, Jacek Rak, Arun Somani, Dimitri Papadimitriou & Alexey Vinel, Piscataway: IEEE Press, 2016, p. 281-287, article id 7608299Conference paper (Refereed)
    Abstract [en]

    A rich portfolio of services (e.g., road traffic information, maps download, Internet/cloud access) will be delivered to users on wheels through Vehicular Ad Hoc Networks (VANETs).Most of them will be offered by road-side units (RSUs) sparsely deployed along the roads. The prompt access to such services by passing by vehicles highly relies on the efficiency of service announcement procedures performed by the RSUs. In this paper, we present an analytical framework that models the service discovery and access mechanisms in multi-channel vehicular networks. The model accounts for dual-radio devices under different channel configurations for the delivery of announcements (e.g., on the control channel, on a service channel) and related switching mechanisms. Guidelines are suggested for the setting of service announcements parameters and channel configuration to allow providers to boost service provisioning. © 2016 IEEE.

  • 458.
    Campolo, Claudia
    et al.
    Mediterranea University of Reggio Calabria, Reggio Calabria, Italy.
    Molinaro, Antonella
    Mediterranea University of Reggio Calabria, Reggio Calabria, Italy.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Understanding Adjacent Channel Interference in Multi-Channel VANETs2014In: 2014 IEEE Vehicular Networking Conference (VNC) / [ed] Falko Dressler, Onur Altintas, Suman Banerjee, Björn Scheuermann & David Eckhoff, Piscataway, NJ: IEEE Press, 2014, p. 101-104, article id 7013316Conference paper (Refereed)
    Abstract [en]

    Multiple channels have been allocated in the 5 GHz spectrum for vehicular communications worldwide, however, due to the limited allocated bandwidth, simultaneous communications occurring over nearby channels may be affected by adjacent channel interference (ACI). Due to ACI, packet reception may be unsuccessful and transmissions may be delayed. In this work, we investigate the ACI phenomena in multichannel vehicular networks to shed light on their effects, with focus on the transmitter-side. To this purpose, a simple analytical model is introduced along with a preliminary evaluation. Suggestions are also provided about the usage of adjacent channels so to minimize side effects on the communication quality. © 2014 IEEE

  • 459.
    Campolo, Claudia
    et al.
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Molinaro, Antonella
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Vinel, Alexey
    Department of Communications Engineering, Tampere University of Technology, Tampere, Finland.
    Understanding the performance of short-lived control broadcast packets in 802.11p/WAVE Vehicular networks2011In: 2011 IEEE Vehicular Networking Conference (VNC) / [ed] Altintas, O., Chen, W., Heijenk, G. J., Dressler, F., Ekici, E., Kargl, F., Shigeno, H., Dietzel, S., Piscataway, NJ: IEEE Press, 2011, p. 102-108Conference paper (Refereed)
  • 460.
    Campolo, Claudia
    et al.
    Università Mediterranea di Reggio Calabria, Reggio Calabria, Italy.
    Molinaro, Antonella
    Università Mediterranea di Reggio Calabria, Reggio Calabria, Italy.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Lyamin, Nikita
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Service Discovery and Access in Vehicle-to-Roadside Multi-Channel VANETs2015In: 2015 IEEE International Conference on Communication Workshop, Piscataway, NJ: IEEE Press, 2015, p. 2477-2482Conference paper (Refereed)
    Abstract [en]

    A wide portfolio of safety and non-safety services will be provided to drivers and passengers on top of Vehicular Ad Hoc Networks (VANETs).

    Non-safety services are announced by providers, e.g., road-side units (RSUs), on a channel that is different from the one where the services are delivered. The dependable and timely delivery of the advertisement messages is crucial for vehicles to promptly discover and access the announced services in challenging vehicle-to-roadside scenarios, characterized by intermittent and short lived connectivity.

    In this paper, we present an analytical framework that models the service advertisement and access mechanisms in multichannel vehicular networks.

    The model accounts for dual-radio devices, and computes the mean service discovery time and the service channel utilization by considering the disruption periods due to the switching of the RSU from the advertising channel (where announcements are transmitted) to the advertised channel (where services are exchanged), under different channel and mobility conditions. It provides quick insights on parameter settings to allow providers to improve service provisioning. © 2015 IEEE

  • 461.
    Campolo, Claudia
    et al.
    University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Molinaro, Antonella
    University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Zhang, Yan
    Simula Research Laboratory, Fornebu, Norway.
    Modeling and enhancing infotainment service access in vehicular networks with dual-radio devices2016In: Vehicular Communications, ISSN 2214-2096, Vol. 6, p. 7-16Article in journal (Refereed)
    Abstract [en]

    A dedicated spectrum portion at 5 GHz is available to provide services in vehicular environments (e.g., road safety, traffic efficiency, comfort and infotainment services). The multitude of non-safety critical services offered by roadside and mobile providers can be accessed by vehicles under radio coverage if they listen to the advertisement messages announcing the service configuration parameters and tune to the announced frequency to access the service. Due to intermittent and short connectivity periods, timely and successful advertisements reception is crucial to enable a vehicle accessing available services while it is still connected to the provider.

    In this paper, we design an analytical model of the service advertisement and access procedure for dual-radio vehicular devices. Moreover, we enhance the advertisement phase with a simple technique of message repetition and channel switching coordination, which helps in making vehicles aware of local services promptly coping with channel impairments and collisions. The model flexibly accounts for channel switching, message repetitions, access prioritization, and interference by contending traffic on the channel where service announcements are regularly transmitted. ©2016 Elsevier Inc. All rights reserved.

  • 462.
    Campolo, Claudia
    et al.
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Molinaro, Antonella
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Reggio Calabria, Italy.
    Vinel, Alexey
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Zhang, Yan
    Simula Research Laboratory, Fornebu, Norway.
    Modeling Event-Driven Safety Messages Delivery in IEEE 802.11p/WAVE Vehicular Networks2013In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 17, no 12, p. 2392-2395Article in journal (Refereed)
    Abstract [en]

    A stochastic model is designed to assess the delivery performance of event-driven safety messages in IEEE 802.11p/1609.4 vehicular ad-hoc networks (VANETs). The study focuses on the case of a vehicle detecting an unpredictable hazard and broadcasting the alert in the one-hop neighborhood. The model aims at providing quick insights into the impact of the latest WAVE specifications (i.e., traffic differentiation, channel switching) on the delivery of such short-lived alert messages. Results prove that it is accurate in capturing the effect of relevant parameters and show that repeating the alert transmission on the control channel helps to achieve reliable delivery. © 2013 IEEE.

  • 463.
    Campolo, Claudia
    et al.
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria.
    Molinaro, Antonella
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria.
    Vinel, Alexey
    Department of Communications Engineering, Tampere University of Technology.
    Zhang, Yan
    Simula Research Laboratory.
    Modeling Prioritized Broadcasting in Multichannel Vehicular Networks2012In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 61, no 2, p. 687-701Article in journal (Refereed)
    Abstract [en]

    Effective data broadcasting is essential in vehicular networks not only for road-safety message dissemination but also to aid routing and cooperative driving applications through periodic beaconing and to spread network initialization advertisements that are mandatory to support infotainment applications. Broadcast data are neither acknowledged nor retransmitted in case of failure, which raises the possibility of frame loss due to channel errors and collisions with multiple simultaneous broadcasts. This paper aims at modeling periodic broadcasting on the control channel of IEEE Std. 802.11p vehicular networks with multichannel architecture. Unlike previous related work, the proposed novel analytical approach accounts for mutual influence among nodes, frequent periodic updates of broadcasted data, standard network advertisement procedures, and 802.11p prioritized channel access with multichannel-related phenomena under various link quality conditions. © 2012 IEEE.

  • 464.
    Campolo, Claudia
    et al.
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Italy.
    Vinel, Alexey
    Department of Communications Engineering, Tampere University of Technology.
    Molinaro, Antonella
    Dipartimento di Informatica, Matematica, Elettronica e Trasporti, University Mediterranea of Reggio Calabria, Italy.
    Koucheryavy, Yevgeni
    Department of Communications Engineering, Tampere University of Technology.
    Modeling Broadcasting in IEEE 802.11p/WAVE Vehicular Networks2011In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 15, no 2, p. 199-201Article in journal (Refereed)
    Abstract [en]

    IEEE 802.11p/WAVE (Wireless Access in Vehicular Environments) is an emerging family of standards intended to support wireless access in Vehicular Ad Hoc Networks (VANETs). Broadcasting of data and control packets is expected to be crucial in this environment. Both safety-related and non-safety applications rely on broadcasting for the exchange of data or status and advertisement messages. Most of the broadcasting traffic is designed to be delivered on a given frequency during the control channel (CCH) interval set by the WAVE draft standard. The rest of the time, vehicles switch over to one of available service channels (SCHs) for non-safety related data exchange. Although broadcasting in VANETs has been analytically studied, related works neither consider the WAVE channel switching nor its effects on the VANET performance. In this letter, a new analytical model is designed for evaluating the broadcasting performance on CCH in IEEE 802.11p/WAVE vehicular networks. This model explicitly accounts for the WAVE channel switching and computes packet delivery probability as a function of contention window size and number of vehicles. © 2011 IEEE.

  • 465.
    Campos, Jaime
    Linnaeus University, Faculty of Technology, Department of Informatics. LNU.
    Modelling the Web 2.0 oriented sites for the e-maintenance applications2013In: International congress of condition monitoring and diagnostic engineering management: Congress Proceedings, COMADEM 2013, 11-13 June, Helsiki, 2013, p. 52-57Conference paper (Refereed)
  • 466.
    Campos, Jaime
    Linnaeus University, Faculty of Technology, Department of Informatics.
    The ICT Systems Developments in Maintenance: From Data Processing into Knowledge Driven Approaches2014In: Proceedings of the 15th European conference on Knowledge management, (ECKM 2014): vol. 1-3 / [ed] Vivas C & Sequeira P, Academic Conferences Limited, 2014, p. 182-188Conference paper (Refereed)
    Abstract [en]

    The paper goes through the developments of Information and Communication Technologies (ICTs) in the area of Condition Monitoring (CM) and Maintenance with the aim to understand the current state of the ICTs developments in the area of interest as well as their future prospects. The findings are ordered into a framework, which emphasizes the diverse maturity aspects when it comes to the use of these technologies. The results show that the researchers are working with various ICT applications that are in the different eras of the framework. There are findings that support the last era, i.e. the fourth era, but those findings are fewer. However, the applications that support this last era, even if they are at the primary stage, is the e-maintenance approach especially when the knowledge driven approaches are considered in their applications. The e-maintenance approach apart from its integration capabilities also considers other important aspects such as collaboration, cooperation, and organisational learning as well as companies' strategies such as the condition based maintenance, etc. it is, therefore, important to consider the e-maintenance approach as a facilitator for the entrance into the fourth era, which promises sustainability in the use of the ICTs for the domain of interests as well as higher organizational performance

  • 467.
    Campos, Jaime
    et al.
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Jantunen, Erkki
    VTT Technical Research Centre of Finland, Finland.
    Baglee, David
    University of Sunderland, UK.
    Fumagalli, Luca
    Politecnico di Milano, Italy .
    Emmanouilidis, Christos
    Cranfield University, UK.
    Gilabert, Eduardo
    Fundación TEKNIKER, Spain.
    Mobile Information Systems in Maintenance Engineering and Asset Management2016In: Journal of Societal Studies, ISSN 2029-2244, Vol. 8, no 2, p. 180-197Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to provide a profound insight into important characteristics with regard to the integration of mobile technology into the area of industrial maintenance. The aspects highlighted in the paper uncover, for instance, acceptance models and best practices, as well as the financial impact of mobile technologies in the domain of interest. Moreover, the paper pinpoints some important characteristics that impede full integration of these technologies into this area. In addition, the economic benefits and the current situation with regard to mobile integration are highlighted. In addition, relevant literature and theories are analysed and discussed. Furthermore, the industrial integration of mobile technologies is outlined. The results indicate that there is a tendency to place an emphasis on the technical aspects of mobile devices rather than on understanding the organisational context, which affects the integration of mobile technologies into this domain.

    The work provides a thorough understanding of best practices and aspects to consider for the successful integration of mobile technologies in this area. This is because the use of mobile devices enables maintenance staff to gain access to information and services pertaining to the task in hand in real time, as long as some form of network access is provided. Users of these devices thus become mobile actors who dynamically interact with the physical environment in the workplace and support information systems, leading to a faster response to events and improved organizational performance.

  • 468.
    Campos, Jaime
    et al.
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Jantunen, Erkki
    VTT Technical Research Centre of Finland, Finland.
    Baglee, David
    University of Sunderland, UK .
    Gilabert, Eduardo
    Fundación TEKNIKER, Spain.
    Fumagalli, Luca
    Politecnico di Milano, Italy.
    Emmanouilidis, Christos
    ATHENA Research & Innovation Centre, Greece .
    The Use of Mobile Technologies and Their Economic Benefits in Maintenance2016In: Proceedings of the 10th World Congress on Engineering Asset Management (WCEAM 2015) / [ed] Koskinen, K.T., Kortelainen, H., Aaltonen, J., Uusitalo, T., Komonen, K., Mathew, J., Laitinen, J. (Eds.), Springer, 2016, p. 113-119Conference paper (Refereed)
    Abstract [en]

    The use of mobile devices enables maintenance staff to gain access to information and services relevant to the task in hand in near real time and wherever some form of network access is provided. Essentially, mobile device users become mobile actors who dynamically interact with the physical environment, i.e. workplace, and supporting information systems, leading to faster response to events and an increased performance. This paper provides insight into the acceptance prospects and best practices of the mobile technologies in the area of maintenance. Furthermore, the potential financial impact is discussed as a key driver for the adoption of mobile technologies in the maintenance practice.

  • 469.
    Campos, Jaime
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics. LNU.
    Kortelainen, Juha
    VTT Technical Research Centre of Finland.
    Jantunen, Erkki
    VTT Technical Research Centre of Finland.
    Product Lifecycle Simulation Applying Semantic Data Management2011In: Product Lifecycle Management: Virtual Product Lifecycles for Green Products and Services:Proceedings of the PLM11 conference held at the Eindhoven University of Technology, The Netherlands, 11-13 July 2011 / [ed] Pels, H.J., Bouras, A., & McMahon, C., 2011, p. 455-464Conference paper (Refereed)
    Abstract [en]

    Product lifecycle simulation (PLCS) has been given ever moreattention as the manufacturers are competing with the quality and lifecyclecosts of their products. Especially, the need of companies to try to get a strongposition in providing services for their products and thus to make themselvesless vulnerable to changes in the market has led to high interest in PLCS. Ashort summary of current status of PLCS is presented especially related to thepoor integration of data in product lifecycle management systems and in PLCS.The potential of applying semantic data management to solve these problems isthoroughly discussed in the light of recent development. A basic roadmap howthe above-described problems could be tackled with open software solutions ispresented. Finally, this paper reviews the emergent Web technologies such asthe Semantic Web framework and the Web services.

  • 470.
    Campos, Jaime
    et al.
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Sharma, Pankaj
    Indian Institute of Technology Delhi, India.
    Jantunen, Erkki
    VTT Technical Research Centre of Finland, Finland.
    Baglee, David
    University of Sunderland, UK.
    Fumagalli, Luca
    Politecnico di Milano, Italy.
    Business Performance Measurements in Asset Management with the Support of Big Data Technologies2017In: Management Systems in Production Engineering, E-ISSN 2450-5781, Vol. 25, no 3, p. 143-149Article in journal (Refereed)
    Abstract [en]

    The paper reviews the performance measurement in the domain of interest. Important data in asset management are further, discussed. The importance and the characteristics of today’s ICTs capabilities are also mentioned in the paper. The role of new concepts such as big data and data mining analytical technologies in managing the performance measurements in asset management are discussed in detail. The authors consequently suggest the use of the modified Balanced Scorecard methodology highlighting both quantitative and qualitative aspects, which is crucial for optimal use of the big data approach and technologies.

  • 471.
    Cao, Le Phuong
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Optimal transmit strategy for MIMO channels with joint sum and per-antenna power constraints2017In: 2017 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), IEEE, 2017, p. 3569-3573Conference paper (Refereed)
    Abstract [en]

    This paper studies optimal transmit strategies for multiple-input multiple-output (MIMO) Gaussian channels with joint sum and per-antenna power constraints. It is shown that if an unconstraint optimal allocation for an antenna exceeds a per-antenna power constraint, then the maximal power for this antenna is used in the constraint optimal transmit strategy. This observation is then used in an iterative algorithm to compute the optimal transmit strategy in closed-form. Finally, a numerical example is provided to illustrate the theoretical results.

  • 472.
    Cao, Wei Qiu
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    A new Content Distribution Network architecture - PlentyCast2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Content Distribution Networks have existed for some years. They involve the following problem domains and have attracted attention both in academic research and industry: content replica placement, content location and routing, swarm intelligence, and overlay network self-organization for this type of distributed system. In this project, we propose a novel Content Distribution Network architecture – PlentyCast. This study focuses on improving access latency, network scalability, high content availability, low bandwidth consumption, and improving infrastructure performance for Content Distribution Networks. Outstanding problems such as: Flash crowd, DoS, and difficulty of traffic engineering due to Peer-to-Peer are addressed.

  • 473.
    Carlos, Perez Penichet
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hermans, Frederik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Varshney, Ambuj
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Augmenting IoT networks with backscatter-enabled passive sensor tags2016In: Proceedings of the 3rd Workshop on Hot Topics in Wireless, 2016, p. 23-27Conference paper (Refereed)
    Abstract [en]

    The sensing modalities available in an Internet-of-Things (IoT) network are usually fixed before deployment, when the operator selects a suitable IoT platform. Retrofitting a deployment with additional sensors can be cumbersome, because it requires either modifying the deployed hardware or adding new devices that then have to be maintained. In this paper, we present our vision and work towards passive sensor tags: battery-free devices that allow to augment existing IoT deployments with additional sensing capabilities without the need to modify the existing deployment. Our passive sensor tags use backscatter transmissions to communicate with the deployed network. Crucially, they do this in a way that is compatible with the deployed network's radio protocol, and without the need for additional infrastructure. We present an FPGA-based prototype of a passive sensor tag that can communicate with unmodified 802.15.4 IoT devices. Our initial experiments with the prototype support the feasibility of our approach. We also lay out the next steps towards fully realizing the vision of passive sensor tags.

  • 474.
    Carlos, Pérez Penichet
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hermans, Frederik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    On Limits of Constructive Interference in Backscatter Systems2017In: Global Internet of Things Summit (GIoTS), 2017, IEEE, 2017, p. 178-182Conference paper (Other academic)
    Abstract [en]

    Backscatter communication reduces the energy consumption of resource-constrained sensors and actuators by several orders of magnitude as it avoids the resource-consuming need to generate a radio wave. Many backscatter systems and applications suffer from low communication range. By exploiting the collective power of several tags that transmit the same data simultaneously, constructive interference may help to remedy this problem and increase the communication range. When several tags backscatter the same signal simultaneously it is not necessarily true that constructive interference occurs. As our theoretical results and previous work indicate the interference might also be destructive. Our experimental results on real hardware suggest that exploiting constructive interference to increase the communication range requires careful coordination which is difficult in decentralized settings.

  • 475.
    Carls, Johan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    NGN – Nästa Generations Nätverk (Nätverks- och Riskanalys) för Piteå Kommun2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    My mission has been to technical documentation and identify Piteå Municipality's existing network infrastructure. Everything has been summarized in several different areas: Network Services, Network-related services, Technology, Management/Control and Security. A risk analysis has been developed where I have identified a total of 28 risks and deficiencies in the municipality's existing network infrastructure. 4 risks and deficiencies under Design, 9 risks and deficiencies under Security, 5 risks and deficiencies under Network related services, 2 risks and deficiencies under Network Services, 2 risks and deficiencies under Management/Control and 5 risks and deficiencies under Technology. All risks and deficiencies have been categorized in order of low, medium and high risks and deficiencies of varying action time (0-24 + months). This final report has been the basis for then developing a new future-proof network infrastructure using a Requirements and Vision for the Municipality of Piteå.

  • 476.
    Carlsson, Daniel
    KTH, School of Information and Communication Technology (ICT).
    Dynamics AX in the Cloud: Possibilities and Shortcomings2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The usage of the cloud is rapidly increasing and is something that is of large interest to everyone involved in technology. The purpose of this thesis is to examine the benefits and possible shortcomings of using Microsoft Dynamics AX in the cloud, specifically Microsoft Azure, instead of using local datacenters. This thesis project has been done at Scania IT using their implementation of Dynamics AX.

    This thesis project consists of an extensive literature study regarding both ERP Systems as well as other systems in regards to the cloud. It was decided early on to focus on the new version of Dynamics AX, which currently is only available in the cloud and compare this implementation to the two versions that the majority are using today, AX 2009 and AX 2012. The benefits of AX and Azure both being Microsoft products are clear with the welldesigned integrations and support all the way through the clients to the servers regarding backups and load balancing. It is shown how the developers have to work differently in regards to integrations with outside systems, especially in regards to AX 2009 with the frameworks having changed. The addition of Data Entities mean that the developers can save a lot of time by only needing a reference to the location of the object in the database instead of having to keep track of all the tables themselves.

    The analysis focuses on the differences in four different areas, performance & accessibility, scalability, cost savings as well as security & privacy. The background knowledge that is being used for the analysis primarily comes from the literature study as well as knowledge gained by studying the implementation at Scania today. The result shows that there are clear advantages regarding performance, cost savings and especially accessibility, however it is also clear that laws in a lot of countries still have not caught up with the fact that it is possible to use the cloud for data storage these days. Which in turn means that the best move in the near future for the majority of ERP users would be either a hybrid or private cloud within the borders of the same country.

  • 477.
    Carlsson, Erik
    Linköping University, Department of Electrical Engineering, Computer Engineering.
    Synchronization of Distributed Units without Access to GPS2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Time synchronization between systems having no external reference can be an issue in small wireless node-based systems. In this thesis a transceiver is designed and implemented in two separate systems. Then the timing algorithm of "TwoWay Time Transfer" is then chosen to correct any timing error between the two free running clocks of the systems. In conclusion the results are compared towards having both systems get their timing based on GPS timing.

  • 478.
    Carlsson, Henric
    University of Skövde, School of Informatics.
    Using A Recommender To Influence Consumer Usage2013Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    In this dissertation, the issues of the increased awareness of energy use are considered. Energy technologies are continuously improved by energy retailers and academic researchers. The Smart Grid are soon customary as part of the energy domain. But in order to improve energy efficiency the change must come from the consumers. Consumers should be active decision makers in the Smart Grid domain and therefor a Recommender system suits the Smart Grid and enables customers. Customers will not use energy in the way energy retailers, and politicians advocates instead they will do what fits them. By investigating how a Recommender can be built in the Smart Grid we focus on parameters and information that supports the costumers and enables positive change. An investigation of what customers perceive as relevant is pursued as well as how relevancy can adjust the system. A conceptual model of how to build a Recommender is rendered through a literature review, a group interview and a questionnaire.

  • 479.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Optimized eeeBond: Energy Efficiency with non-Proportional Router Network Interfaces2016In: PROCEEDINGS OF THE 2016 ACM/SPEC INTERNATIONAL CONFERENCE ON PERFORMANCE ENGINEERING (ICPE'16), ACM Digital Library, 2016, p. 215-223Conference paper (Refereed)
    Abstract [en]

    The recent Energy Efficient Ethernet (EEE) standard and the eBond protocol provide two orthogonal approaches that allow significant energy savings on routers. In this paper we present the modeling and performance evaluation of these two protocols and a hybrid protocol. We first present eeeBond, pronounced ``triple-e bond'', which combines the eBond capability to switch between multiple redundant interfaces with EEE's active/idle toggling capability implemented in each interface. Second, we present an analytic model of the protocol performance, and derive closed-form expressions for the optimized parameter settings of both eBond and eeeBond. Third, we present a performance evaluation that characterizes the relative performance gains possible with the optimized protocols, as well as a trace-based evaluation that validates the insights from the analytic model. Our results show that there are significant advantages to combine eBond and EEE. The eBond capability provides good savings when interfaces only offer small energy savings when in short-term sleep states, and the EEE capability is important as short-term sleep savings improve.

  • 480.
    Carlsson, Robin
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Investigation and Implementation of Coexistence Tool for Antennas2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the increase of the number of radios and antennas on today’s systems, the risk of co-site interference is very high. Intermodulation product and antenna coupling are two common sources of interference. The thesis investigates some features of a radio system, like antenna types, receiver parameters, intermodulation products and isolation, and suggests how this knowledge can be used to minimize the risk of co-site interference. The goal is to maximize the isolation between the antennas, by good frequency planning, the use of filters and taking great care in antenna placement. A first version of an analysis software was developed where transmitters and receivers can be paired and evaluated. An intermodulation product calculator was also implemented, to easily find which products are an issue and where they originate. The goal of the software is to be simple to use and easy to adapt to different setups and situations. It should also be easy to upgrade with new features.

  • 481.
    Carlsson, Stefan
    et al.
    KTH, Superseded Departments, Teleinformatics.
    Halén, Erik
    KTH, Superseded Departments, Teleinformatics.
    Mobile Internet: Content Adaptation for Limited Devices2000Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates how to adapt content on the Web to the limited I/O capabilities of today’s WAP (Wireless Application Protocol) devices and how to translate from HTML to WML (Wireless Markup Language). We also give an overview of WAP and Mobile Internet and a brief analysis of the future of WAP.

    To evaluate different methods of adaptation, two existing Web sites are adapted to WML. Three different methods are tried and evaluated: The first method is a brute force WML re-coding of the site. The second method is an XML based solution that separates the data from the presentation and uses different XSLT (eXtensible Style sheet Language Transformations) style sheets for different devices. The third method uses a proxy that translates a requested page from HTML to WML. The proxy evaluated here is Oracle’s Portal-to-Go in its semi-automated form, i.e. where it is manually pre-configured for every site it adapts.

    An important issue is whether to adapt specifically for each device or whether to use generically written WML for the entire range of WAP devices. Another issue is that a WAP device only can receive a limited amount of information at a time, and this limit varies between different devices.

  • 482.
    Carlsson, Ulrika
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Stenhammar, Marie
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Sociala medier: och kundinteraktion i mindre företag 2011Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Title: Social Media – And customer interaction in smaller firms

    Seminar date: 2011-06-10

    Course: Information Logistics, D-level.

    Authors: Marie Stenhammar and Ulrika Carlsson

    Advisor: Jaime Campos

    Key words: Social Media, Web 2.0, Co-creation, Viral marketing, Word of Mouth, smaller firms

    Purpose: This paper aims to describe the relevance of social media to smaller firms, the challenges and opportunities they face and what strategies they use, in the interaction with their customers.

    Methodology: The study is qualitative in nature and has an abductive approach. The empirical material consists of in-depth interviews with chosen companies and Internet observations.

    Theoretical perspectives: Social Media, Web 2.0, Co-creation, Viral marketing, Word of Mouth

    Empirical foundation: The study takes its empirical base from in-depth interviews with representatives from the small companies and internet observations connected to these.

    Conclusions: Smaller companies have great interest in social media. They preferably use Facebook, blogs, YouTube and Twitter. Their strategy is mainly to be very active and update their social media regularly. The opinion of the companies is that social media offer several possibilities such as stronger relationships with customers and the ability to collect information about the market.

  • 483.
    Carrara, Elisabetta
    KTH, Superseded Departments, Teleinformatics.
    Wireless Adaptation of a Security Management Protocol Suite1999Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Internet Security is rapidly increasing in importance, as Internet itself is spreading out so fast. The IETF Security working group has defined the "IP Security Protocol Suite", a set of protocols that aim at securing the IP layer, so providing general security services for all kinds of applications.

    The IPSec Protocol Suite is completed by a protocol for key management and key exchange, the "Internet Security Association and Key Management Protocol (ISAKMP)" . It is currently an IETF Proposed Standard for the Internet.

    In this thesis we describe ISAKMP, and also its use together with the Internet Key Exchange (IKE) protocol, as a negotiation and key exchange protocol for IPSec. A general overview of cryptography is also provided, since ISAKMP widely uses modern cryptographic techniques.

    ISAKMP flexibility is at the cost of complexity and increased packet traffic. This should be faced in constrained communications, such as wireless. Therefore, this thesis introduces some proposals for a compressed version of the protocol, trying to reduce the number of handshakes and the number of transmitted bytes without significantly decreasing the security level.

    The model is based on the use of a Proxy, which follows the compressed version of ISAKMP on the side of the  mobile node, and then switches to the original version of the protocol on the wired side with the second peer. Ad-hoc solutions are adopted, and security implications are taken into account.

  • 484. Casati, Fabio
    et al.
    Daniel, Florian
    Dantchev, Guenadi
    Eriksson, Joakim
    Finne, Niclas
    Karnouskos, Stamatis
    Montera, Patricio Moreno
    Mottola, Luca
    Oppermann, Felix Jonathan
    Picco, Gian Pietro
    Quartulli, Antonio
    Römer, Kay
    Spiess, Patrik
    Tranquillini, Stefano
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Towards business processes orchestrating the physical enterprise with wireless sensor networks2012In: ICSE, 2012, p. 1357-1360Conference paper (Refereed)
  • 485.
    Casselgren, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Reusable road condition information system for traffic safety and targeted maintenance2017In: IET Intelligent Transport Systems, ISSN 1751-956X, E-ISSN 1751-9578, Vol. 11, no 4, p. 230-238Article in journal (Refereed)
    Abstract [en]

    Driver awareness of current winter road conditions (RCs) is known to affect the frequency of accidents due to sudden changes in these conditions. For example, partially icy roads that appear during autumn in northern areas typically result in collisions and ditch runs unless the drivers are generally aware of the situation. Availing motorists who drive under winter RCs of enhanced information is therefore highly desirable to increase their awareness of hazardous driving conditions. Such conditions need to be predicted ahead of time and presented to drivers before they attempt slippery road sections. Moreover, the identification of slippery RCs should quickly trigger targeted road maintenance to reduce the risk of accidents. This study presents a scalable and reusable collaborative intelligent transport system, herein referred to as an RC information system (RCIS). RCIS provides accurate RC predictions and forecasts based on RC measurements, road weather observations, and short-term weather forecasts. The prediction methods in the context of the distributed RCIS have been tested using a prototype implementation. These tests confirmed that these inputs could be combined into useful and accurate information about winter RCs that can be adapted for different types of users.

  • 486.
    Castellanos Ardila, Julieth Patricia
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Gallina, Barbara
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards Efficiently Checking Compliance Against Automotive Security and Safety Standards2017In: The 7th IEEE International Workshop on Software Certification WoSoCer 2017, 2017, p. 317-324Conference paper (Refereed)
    Abstract [en]

    The growing connectivity of the systems that we rely on e.g. transportation vehicles is pushing towards the introduction of new standards aimed at providing a baseline to address cybersecurity besides safety. If the interplay of the two normative spaces is not mastered, compliance management might become more time consuming and costly, preventing engineers from dedicating their energies to system engineering. In this paper, we build on top of previous work aimed at increasing efficiency and confidence in compliance management. More specifically, we contribute to building a terminological framework needed to enable the systematization of commonalities and variabilities within ISO 26262 and SAE J3061. Then, we focus our attention on the requirements for software design and implementation and we use defeasible logic to prove compliance. Based on the compliance checking results, we reveal reuse opportunities. Finally, we draw our conclusions and sketch future research directions.

  • 487.
    Cavdar, Cicek
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ruiz, M.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Velasco, L.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Design of green optical networks with signal quality guarantee2012In: IEEE International Conference on Communications, IEEE , 2012, p. 3025-3030Conference paper (Refereed)
    Abstract [en]

    Energy consumption of communication networks is growing very fast due to the rapidly increasing traffic demand. Consequently, design of green communication networks gained a lot of attention. In this paper we focus on optical Wavelength Division Multiplexing (WDM) networks, able to support this growing traffic demand. Several energy-aware routing and wavelength assignment (EA-RWA) techniques have been proposed for WDM networks in order to minimize their operational cost. These techniques aim at minimizing the number of active links by packing the traffic as much as possible, thus avoiding the use of lightly loaded links. As a result, EA-RWA techniques may lead to longer routes and to a high utilization on some specific links. This has a detrimental effect on the signal quality of the optical connections, i.e., lightpaths. In this study we quantify the impact of power consumption minimization on the optical signal quality. and address this problem by proposing a combined impairment and energy-aware RWA (IEA-RWA) approach. Towards this goal we developed a complete mathematical model that incorporates both linear and non-linear physical impairments together with an energy efficiency objective. The IEA-RWA problem is formulized as a Mixed Integer Linear Programming (MILP) model where both energy efficiency and signal quality considerations are jointly optimized. By comparing the proposed IEA-RWA approach with existing RWA (IA-RWA and EA-RWA) schemes, we demonstrate that our solution allows for a reduction of energy consumption close to the one obtained by EA-RWA approaches, while still guaranteeing a sufficient level of the optical signal quality.

  • 488. Cea, Mauricio G.
    et al.
    Goodwin, Graham C.
    Wigren, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Model predictive zooming power control in future cellular systems under coarse quantization2012In: Proc. 76th Vehicular Technology Conference, Piscataway, NJ: IEEE, 2012Conference paper (Refereed)
  • 489. Cen, M.
    et al.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Mégret, P.
    Moeyaert, V.
    Wuilpart, M.
    Fast and simple fault monitoring for long-reach passive optical networks2014In: 2014 European Conference on Optical Communication, (ECOC), IEEE , 2014, p. 6964070-Conference paper (Refereed)
    Abstract [en]

    We propose a fast and simple monitoring system based on multi-wavelength bi-directional transmission reflection analysis approach for long-reach passive optical networks. Both experimental and simulation results have demonstrated the proposed system can reach high accuracy for fault localization.

  • 490. Cen, Song
    et al.
    Zhang, Xingjun
    Lei, Ming
    Fowler, Scott
    Linköping University, Department of Science and Technology, Communications and Transport Systems.
    Dong, Xiaoshe
    Stochastic geometry modeling and energy efficiency analysis of millimeter wave cellular networks2018In: Wireless networks, ISSN 1022-0038, E-ISSN 1572-8196, Vol. 24, no 7, p. 2565-2578Article in journal (Refereed)
    Abstract [en]

    Current wireless networks face unprecedented challenges because of the exponentially increasing demand for mobile data and the rapid growth in infrastructure and power consumption. This study investigates the optimal energy efficiency of millimeter wave (mmWave) cellular networks, given that these networks are some of the most promising 5G-enabling technologies. Based on the stochastic geometry, a mathematical framework of coverage probability is proposed and the optimal energy efficiency is obtained with coverage performance constraints. Numerical results show that increasing the base station density damages coverage performance exceeding the threshold. This work demonstrates an essential understanding of the deployment and dynamic control of energy-efficient mmWave cellular networks.

  • 491.
    Cen, Song
    et al.
    Xi An Jiao Tong Univ, Peoples R China.
    Zhang, Xingjun
    Xi An Jiao Tong Univ, Peoples R China.
    Lei, Ming
    Xi An Jiao Tong Univ, Peoples R China.
    Fowler, Scott
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Dong, Xiaoshe
    Xi An Jiao Tong Univ, Peoples R China.
    Stochastic geometry modeling and energy efficiency analysis of millimeter wave cellular networks2018In: Wireless networks, ISSN 1022-0038, E-ISSN 1572-8196, Vol. 24, no 7, p. 2565-2578Article in journal (Refereed)
    Abstract [en]

    Current wireless networks face unprecedented challenges because of the exponentially increasing demand for mobile data and the rapid growth in infrastructure and power consumption. This study investigates the optimal energy efficiency of millimeter wave (mmWave) cellular networks, given that these networks are some of the most promising 5G-enabling technologies. Based on the stochastic geometry, a mathematical framework of coverage probability is proposed and the optimal energy efficiency is obtained with coverage performance constraints. Numerical results show that increasing the base station density damages coverage performance exceeding the threshold. This work demonstrates an essential understanding of the deployment and dynamic control of energy-efficient mmWave cellular networks.

  • 492.
    Chabouni (nee Talbi), Sami
    KTH, Superseded Departments, Teleinformatics. KTH, School of Information and Communication Technology (ICT).
    Investigation and Prototyping of a web based manager in a GSM SIM Application Platform1998Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The growing need for communication in the world has increased the use of telephony and has therefore led to several technical innovations and improvements in the field of telecommunications. As countries develop their infrastructure new ways of communicating arise. But the technical innovations do not completely guide the evolution of the infrastructure. Many times, the way people act, i.e., their mentality and traditions, decides how to invest in the infrastructure. As basic infrastructure is being built in some developing countries, others come up with new revolutionary solutions to replace old infrastructure and, for some developing countries the question arises whether to continue to invest several hundreds of millions of dollars in traditional telephony wiring. The cellular technique is revolutionary enough to be applied in countries that haven’t yet built a telephony network covering an adequate area of the country. In these countries, investments might therefore be focused on the cellular technique, rather than continuing to invest in cable networking. Thus adapting cellular technology to a worldwide distribution is necessary when it comes to administration and subscriber payment. The communication providers meet administrative obstacles when it comes to telephony services for a large-scale distribution. Will the subscribers pay for the services we offer them?

    Using Subscriber Identity Modules (SIM) one way to solve this problem is to define a prepaid scheme. It is based on the fact that the subscriber uses a unique identifier to make a connection and is billed using this identifier. The service provider is free to choose if the subscriber is thrustworthy or not and thus must pay in advance for the services or billed retroactively. This general way of solving administration problems does not apply only to developing countries where retroactive billing isn’t a common tradition. It is equally applicable to industrial countries where some people are banned from credibility for a couple of years because they haven’t paid their bills in time, or just because they don’t have employment at the time of their subscription application.

    To be in possession of a telephone is everyone’s right in most of the industrialized countries.

  • 493.
    Chairetakis, Eleftherios
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Alkudhir, Bassam
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Mystridis, Panagiotis
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Deployment of Low Interaction Honeypots in University Campus Network2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Large scale networks face daily thousands of network attacks. No matter the strength of the existing security defending mechanisms, these networks remain vulnerable, as new tools and techniques are being constantly developed by hackers. A new promising technology that lures the attackers in order to monitor their malicious activities and divulge their intentions is emerging with Virtual Honeypots. In the present thesis, we examine an extensive security mechanism based on three different open source low interaction honeypots. We implement this mechanism at our university campus network in an attempt to identify the potential threats and methods used against our network. The data gathered by our honeypots reveal valuable information regarding the types of attacks, the vulnerable network services within the network and the malicious activities launched by attackers.

  • 494.
    Chamoun, Michel
    et al.
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Alizadeh, Maryam
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Enhancing Integrated Systems Through Automation2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In general, when working with the robot industry, there are many factors to consider. Therefore, the process from a non-existing product to an existing product involves many steps that can be time-to consume and error-prone. This thesis will examine the opportunities for automation in the industrial system and the problems that could occur. A little bit of the focus will also be put on Domain Specific Language (DSL) and the exchange of data between two DSLs.The automation of the industry is getting a big thing and there exist ways to integrate software automation within the industry. The research has been done by literature studies and experimenting with a software to exchange information between two DSL-applications. The result shows that there are some standard technologies that could be used in the integration of automation software, but also why automatization could create other problems. The result also shows that it’s possible to exchange information between two DSLs but it can be a little bit complicated.

  • 495.
    Chandhar, Prabhu
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Danev, Danyo
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Massive MIMO as Enabler for Communications with Drone Swarms2016In: 2016 INTERNATIONAL CONFERENCE ON UNMANNED AIRCRAFT SYSTEMS (ICUAS), IEEE , 2016, p. 347-354Conference paper (Refereed)
    Abstract [en]

    Massive multiple-input multiple-output (MIMO) is an emerging technology for mobile communications, where a large number of antennas are employed at the base station to simultaneously serve multiple single-antenna terminals with very high capacity. In this paper, we study the potentials and challenges of utilizing massive MIMO for unmanned aerial vehicles (UAVs) communication. We consider a scenario where multiple single-antenna UAVs simultaneously communicate with a ground station (GS) equipped with a large number of antennas. Speci[1]cally, we discuss the achievable uplink (UAV to GS) capacity performance in the case of line-of-sight (LoS) conditions. We also study the type of antenna polarization that should be used in order to maintain a reliable communication link between the GS and the UAVs. The results obtained using a realistic geometric model show that massive MIMO is a potential enabler for high-capacity UAV network

  • 496.
    Chandhar, Prabhu
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Danev, Danyo
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    On Ergodic Rates and Optimal Array Geometry in Line-of-Sight Massive MIMO2016Conference paper (Refereed)
    Abstract [en]

    We investigate the achievable ergodic rate of Massive multi-input-multi-output (MIMO) system in environments with high mobility and line-of-sight (LoS). A 3-dimensional geometric model with uniform rectangular array at the basestation (BS) is used for the investigation. We derive a closed formexpression for a lower bound on the uplink ergodic rate takinginto account imperfections of the channel state information,number of BS antennas, antenna spacing, and spatial distributionof user terminals. The results show that, in LoS Massive MIMO, when the terminals are spherically uniformly distributed around the BS, the ergodic rate is maximized for antenna spacing equal to integer multiples of one-half wavelength.

  • 497. Chandu, Chiranjeevi
    Region of Interest Aware and Impairment Based Image Quality Assessment2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 498.
    Chang, Peiliang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Area Spectral and Energy Efficiency Analysis of Cellular Networks with Cell DTX2015In: IEEE Globecom 2015 , San Diego, December 6th-10th, 2015, IEEE conference proceedings, 2015, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Cell discontinuous transmission (DTX) has been proposed as an effective solution to reduce energy consumption of cellular networks. In this paper, we investigate the impact of network traffic load on area spectral efficiency (ASE) and energy efficiency (EE) of cellular networks with cell DTX. Closedform expressions of ASE and EE as functions of traffic load for cellular networks with cell DTX are derived. It is shown that ASE increases monotonically in traffic load, while EE depends on the power consumption of base stations in sleep mode. If this power consumption is larger than a percentage of the active-mode power consumption, EE increases monotonically with traffic load and is maximized when the network is fully loaded. Otherwise, EE first increases and then decreases in traffic load. In this case, ASE and EE are maximized with different loads. The percentage threshold only depends on the path loss exponent of radio propagation environment and is calculated to be 56.2% when the path loss exponent is 4.

  • 499.
    Chang, Peiliang
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy and Spectral Efficiency of Cellular Networks with Discontinuous Transmission2017In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, no 5, p. 2991-3002Article in journal (Refereed)
    Abstract [en]

    Cell discontinuous transmission (DTX) has been proposed as a solution to reduce energy consumption of cellular networks. This paper investigates the impact of network traffic load on spectral and energy efficiency of cellular networks with DTX. The SINR distribution as a function of traffic load is derived firstly. Then sufficient condition for ignoring thermal noise and simplifying the SINR distribution is investigated. Based on the simplified SINR distribution, the network spectral and energy efficiency as functions of network traffic load are derived. It is shown that the network spectral efficiency increases monotonically in traffic load, while the optimal network energy efficiency depends on the ratio of the sleep-mode power consumption to the active-mode power consumption of base stations. If the ratio is larger than a certain threshold, the network energy efficiency increases monotonically with network traffic load and is maximized when the network is fully loaded. Otherwise, the network energy efficiency firstly increases and then decreases in network traffic load. The optimal load can be identified with a binary search algorithm. The power ratio threshold depends solely on the path loss exponent α, e.g. 56% for α = 4. All these analytic results are further validated by the numerical simulations.

  • 500.
    chang, peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Interference-aware distributed control of cell discontinuous transmission2018In: 2018 IEEE Wireless Communications and Networking Conference (WCNC), 2018Conference paper (Refereed)
    Abstract [en]

    As a main enabler for the next generation (5G) cellular networks, network densification faces challenges in inter-cell interference and energy consumption. Cell discontinuous transmission (DTX) can be employed to reduce both energy consumption of base stations (BSs) and inter-cell interference. In this paper we study the control problem of cell DTX in dense small cell networks (DSCNs). We firstly formulate the network energy efficiency optimization problem. Then a centralized heuristic DTX control algorithm is presented. In order to address the issues of complexity and scalability of the centralized solution, an interference-aware distributed DTX control algorithm is proposed. Discussions on algorithm complexity and implementation are provided. The proposed algorithms are evaluated with numerical simulations. Results show that at high load region, the proposed algorithms can not only enhance network capacity by reducing inter-cell interference by up to 60% but also increase network energy efficiency by switching BSs into micro-sleep mode by 67%.

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