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  • 3051.
    Vaggelakos, Konstantinos
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Optimizing Enterprise Resource Planning systems for mobile applications2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Growing enterprises have growing amounts of information. Making sure that this information is easily accessible to its employees is not an easy task. For this task Enterprise Resource Planning (ERP) systems come in handy. However, the ERP systems contain lots of information and may be too complex to handle this information or may be too slow in sharing this information within the organisation. This thesis introduces a new solution for how mobile applications can connect to an ERP system by exploiting database synchronisation, which allows the employees to get the information wherever they are without the need to directly access the ERP system.

    There are three important questions in this thesis: how the ERP works, how to build a mobile application and, how to build a back end? By combining answers to these questions a whole system is built which is production ready and can copy data between the ERP system and the back end and show the information in a mobile application. The overarching goals were to build a system that could extract data from the ERP system into a proprietary back end and a mobile application that could synchronise with the back end. However, synchronisation between the mobile application and the back end was not implemented due to lack of time. The back end had to be able to scale up to 500 concurrent users and respond within 3 seconds, both of these goals were achieved. The mobile application that was built to display the information to the end user was built with usability in mind, since Netlight wanted a straightforward application that anyone could use. The mobile application was shown to have good usability.

    The results of this thesis project show that building systems around ERPs, instead of inside them, gives these systems the ability to scale, improved the implementation time, and reduced the company’s maintenance efforts.

  • 3052.
    Vajravelu, Dilip Kumar
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Connected Me - Proof of Concept2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Connected Me is a Human Body Communication (HBC) system, which is used fortransferring data through human body. The working principle is based on theorycalled Body Coupled Communication (BCC), which uses electrostatic couplingfor transferring data between device and human body. Capacitance between bodyand electrode acts as an electrical interface between devices. BCC has become aprominent research area in the field of Personal Area Network (PAN), introducedby Zimmerman in 1995. Until now there have been significant amount of paperspublished on human body models and Analog Front End (AFE), but only fewreports are available in digital baseband processing.

    The proposed Human Body Communication (HBC) system consists ofdigital baseband and AFE. Digital baseband is used for transferring data packets.AFE is designed for reconstructing signal shape after signal degradation causedby the human body. This thesis implements high speed serial digital communicationsystem for a human body channel. Available modulation schemes andcharacteristics of the Physical layer (PHY) with respect to human body channelare analyzed before implementing the system. The outcome of this thesis is aFPGA demonstrator that shows the possibility of communication through thehuman body.

  • 3053.
    Vaks, Henrik
    KTH, Superseded Departments, Teleinformatics.
    Wireless Application Protocol: Possibilities and Limitations2000Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Wireless Application Protocol is the first commercial full-scale attempt to connect mobile devices, such as cellular telephones, to services on the Internet. Until now, the network operators have provided the few services available via cellular telephones. That is about to change with the introduction of this new technology, as any third party can act as a service provider for Wireless Application Protocol enabled devices.

    This report is divided into two parts, covering both the theory of the Wireless Application Protocol (and other technologies that could be used in conjunction with it) and also describes the theory and implementation of the application I have created as part of my project.

    The first part thoroughly explains the different layers in the protocol stack, the user agents, and the network structure. It also shows how applications are created and how they operate in different parts of the network. The report covers security issues and services charging, as well as how other technologies could be used together with the Wireless Application Protocol, or how they could replace parts of it. The second part of the report covers the application I have created as part of my project. The application is divided up in order to show different aspects of the Wireless Application Protocol. The emphasis in the project has been on real-time graphic generation, which is exemplified in a vector based map application. The possibilities to connect Wireless Application Protocol applications to databases and peripherals are then explored.

    In conclusion, the fundamental idea of using the Internet as part of the network structure is appealing, both for users and services providers. There are, however, parts of the Wireless Application Protocol that are not realised in the best possible way. There are security weaknesses due to protocol conversions in the middle of the network. Furthermore, as the Wireless Application Protocol specifications specify important parts of the concept as optional, there is a risk of not all devices being able to use all services.

  • 3054.
    Valdenebro González, Fernando
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy-efficient enhancements for IEEE 802.11 WLANs: On the way to enable Cellular/Wi-Fi networks interworking2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Globally, the number of mobile broadband subscriptions is growing and the amount of mobile data traffic is expected to continue to grow rapidly. In the next five years the number of smartphone subscriptions is expected to more than double, while the amount of mobile traffic per active subscription per month of these subscribers is expected to nearly quadruple.

    As a consequence, mobile network operators (MNOs) aim to increase radio network capacity and coverage through heterogeneous deployments. In such heterogeneous networks, wireless local area networks (WLANs) are integrated with wireless wide area networks (WWANs), and there exist a tight interaction between them.

    The almost-ubiquitous support for IEEE802.11 WLANs (usually referred to as Wi-Fi®) makes this radio access technology a potential integrated component of near-future mobile broadband. With Wi-Fi completely integrated into mobile access, MNOs would optimize user experience and use of resources by controlling device’s choice of connectivity. In addition to guaranteeing the best user experience, optimal use of access networks should care about energy-efficiency in order to extend device’s battery life.

    However, the performance of Wi-Fi is far from meet neither energy-efficiency nor quality of service (QoS) user’s requirements. This radio access technology employs an energy-consuming medium access control (MAC) protocol that wastes both bandwidth and device’s energy resources. Therefore, enhanced MAC protocols, cleverly combined with standardized power saving mechanisms such as automatic power save delivery (APSD), would improve both energy-efficiency and QoS in order to enhance WLANs performance and meet user’s expectations.

    In addition, current WLAN discovery mechanisms neither meet requirements of the integrated scenario. Handover operations must be improved in terms of energy efficiency and latency. Consequently, enhanced handover schemes should reduce overall device’s energy consumption during the process, and enable seamless handover between Wi-Fi APs and between cellular/Wi-Fi networks.

    During this thesis project, the main challenges of Wi-Fi towards its integration into mobile access broadband have been analyzed. Consequently, a solution has been designed in order to address the identified challenges, which have been introduced in the previous paragraphs. The solution consists of enhancements for IEEE 802.11 WLANs based on current standards that achieve energy-efficiency and QoS, and facilitate Wi-Fi/cellular networks interworking. Finally, a custom-designed simulator has been used to evaluate the proposed solution.

  • 3055.
    Valderas Núñez, Darwin Abdon
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Integration of sensor nodes with IMS2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The number of users adopting cellular system technologies over the past years has been enormous. This rapid adoption is not comparable in any other technology. Additionally, this has meant that these users have (at least some of the time) the possibility of connectivity to others and to remote services (advanced data and voice services, such as video conferences, mobile TV, navigation, and location services). Increasingly there is no longer a clear boundary between the wide area cellular network and Internet services, as the wide area cellular network is evolving from circuit switched based technologies to an IP based system; hence these wide area cellular systems are simply becoming part of the Internet. This evolution has become a challenge for the telecommunication operators, who have been used to completely controlling their network services and billing. In an attempt to maintain this traditional role for telecommunication operators, telecommunication vendors have introduced the IP Multimedia Subsystem (IMS). A system designed to enable telecommunication operators to be able to bill the user for all of the different services accessed through the wide area cellular network. The goal of such a system is to prevent the telecommunication operators from becoming a "bit pipe" (i.e., simply providing "commodity priced" connectivity). Another relevant change that has direct impact upon this project is the role of mobile handsets as gateways between sensor networks and other networks (especially the wide area cellular networks or Internet). This has lead to integrated solutions, such as the smart house concept, mobile health monitoring, and others.

    This thesis project is a collaboration between Ericsson Research and SUUNTO, in which we have implemented a system for monitoring a user’s heart rate via IMS. The system (has a special focus on sports activities, but it could easily be adapted for health care) is based on internetworking sensor networks, specifically a heart rate belt that transmits data wirelessly, with the IMS network through a mobile phone or a PC. The implemented service runs on top of the SIP Presence service. This project examines two alternatives. The first is a mobile scenario, in which a person is jogging outdoors, in this setting the sensor node communicates via the person’s mobile phone, through the IMS network to a monitoring application. The second scenario is more fixed; such as a gym environment, where the sensor node communicates with a personal computer which in turn publishes the data via IMS. Once the data has been published to the Presence and group management sever, an application server subscribed to the athlete’s Presence service will be notified. The people interested in viewing this data will be able to see it through any web-browser. It will even be possible to archive, and download the data for later use by other applications.

    The system is not optimized yet for a truly real-time communication, as the Presence service does not offer this as other technologies (RTP, SRTP or XMPP) do. There is a big delay difference between the mobile and the fixed solution. We can say that the fixed solution is almost a real-time system for transmitting low frequency data as heart rate information. This project is a first approach to a final high performance system.

  • 3056. Valentini, Roberto
    et al.
    Levorato, Marco
    Donald Bren School of Information and Computer Science.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Performance analysis of IEEE 802.15.3c-Based mmW wireless networks2015In: 2015 49th Annual Conference on Information Sciences and Systems, CISS 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, article id 7086886Conference paper (Refereed)
    Abstract [en]

    The IEEE 802.15.3c standard defines physical layer and Medium Access Control (MAC) specifications for millimeter-Wave Wireless Personal Area Networks. The MAC protocol implements a combination of random channel access and time division multiple access mechanisms to exploit the sectorization granted by the directional antennas. In this work, a novel two-level stochastic model is presented to capture the complex dynamics of channel access in this network environment. Different from prior work, the finite temporal horizon of the channel contention phase is accurately modeled, and the common assumption of saturated terminals is removed. Based on the proposed modeling framework, the allocation of time resource to each sector is optimized to improve the network performance.

  • 3057.
    van Chien, Trinh
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Resource Allocation for Max-Min Fairness in Multi-Cell Massive MIMO2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Massive MIMO (multiple-input multiple-output) is considered as an heir of the multi-user MIMO technology and it has recently gained lots of attention from both academia and industry. By equipping base stations (BSs) with hundreds of antennas, this new technology can provide very large multiplexing gains by serving many users on the same time-frequency resources and thereby bring significant improvements in spectral efficiency (SE) and energy efficiency (EE) over the current wireless networks. The transmit power, pilot training, and spatial transmission resources need to be allocated properly to the users to achieve the highest possible performance. This is called resource allocation and can be formulated as design utility optimization problems. If the resource allocation in Massive MIMO is optimized, the technology can handle the exponential growth in both wireless data traffic and number of wireless devices, which cannot be done by the current cellular network technology.

    In this thesis, we focus on two resource allocation aspects in Massive MIMO: The first part of the thesis studies if power control and advanced coordinated multipoint (CoMP) techniques are able to bring substantial gains to multi-cell Massive MIMO systems compared to the systems without using CoMP. More specifically, we consider a network topology with no cell boundary where the BSs can collaborate to serve the users in the considered coverage area. We focus on a downlink (DL) scenario in which each BS transmits different data signals to each user. This scenario does not require phase synchronization between BSs and therefore has the same backhaul requirements as conventional Massive MIMO systems, where each user is preassigned to only one BS. The scenario where all BSs are phase synchronized to send the same data is also included for comparison. We solve a total transmit power minimization problem in order to observe how much power Massive MIMO BSs consume to provide the requested quality of service (QoS) of each user. A max-min fairness optimization is also solved to provide every user with the same maximum QoS regardless of the propagation conditions.

    The second part of the thesis considers a joint pilot design and uplink (UL) power control problem in multi-cell Massive MIMO. The main motivation for this work is that the pilot assignment and pilot power allocation is momentous in Massive MIMO since the BSs are supposed to construct linear detection and precoding vectors from the channel estimates. Pilot contamination between pilot-sharing users leads to more interference during data transmission. The pilot design is more difficult if the pilot signals are reused frequently in space, as in Massive MIMO, which leads to greater pilot contamination effects. Related works have only studied either the pilot assignment or the pilot power control, but not the joint optimization. Furthermore, the pilot assignment is usually formulated as a combinatorial problem leading to prohibitive computational complexity. Therefore, in the second part of this thesis, a new pilot design is proposed to overcome such challenges by treating the pilot signals as continuous optimization variables. We use those pilot signals to solve different max-min fairness optimization problems with either ideal hardware or hardware impairments.

  • 3058.
    Van Chien, Trinh
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Massive MIMO Communications2017In: 5G Mobile Communications / [ed] Xiang Wei; Zheng Kan; Xuemin Sherman, Switzerland: Springer, 2017, p. 77-116Chapter in book (Refereed)
    Abstract [en]

    Every new network generation needs to make a leap in area data throughput, to manage the growing wireless data traffic. The Massive MIMO technologycan bring at least ten-fold improvements in area throughput by increasing the spec-tral efficiency (bit/s/Hz/cell), while using the same bandwidth and density of basestations as in current networks. These extraordinary gains are achieved by equipping the base stations with arrays of a hundred antennas to enable spatial multiplexing of tens of user terminals. This chapter explains the basic motivations and communication theory behind the Massive MIMO technology, and provides implementation-related design guidelines.

  • 3059.
    Van Chien, Trinh
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    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.
    Downlink Power Control for Massive MIMO Cellular Systems with Optimal User Association2016In: IEEE International Conference on Communications, Malaysia, May 23-27, 2016: proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2016Conference paper (Refereed)
    Abstract [en]

    This paper aims to minimize the total transmit power consumption for Massive MIMO (multiple-input multiple-output) downlink cellular systems when each user is served by the optimized subset of the base stations (BSs). We derive a lower bound on the ergodic spectral efficiency (SE) for Rayleigh fading channels and maximum ratio transmission (MRT) when the BSs cooperate using non-coherent joint transmission. We solve the joint user association and downlink transmit power minimization problem optimally under fixed SE constraints. Furthermore, we solve a max-min fairness problem with user specific weights that maximizes the worst SE among the users. The optimal BS-user association rule is derived, which is different from maximum signal-to-noise-ratio (max-SNR) association. Simulation results manifest that the proposed methods can provide good SE for the users using less transmit power than in small-scale systems and that the optimal user association can effectively balance the load between BSs when needed.

  • 3060.
    Van Chien, Trinh
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    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.
    Joint Pilot Design and Uplink Power Allocation in Multi-Cell Massive MIMO Systems2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 3, p. 2000-2015Article in journal (Refereed)
    Abstract [en]

    This paper considers pilot design to mitigate pilot contamination and provide good service for everyone in multi-cell Massive multiple input multiple output (MIMO) systems. Instead of modeling the pilot design as a combinatorial assignment problem, as in prior works, we express the pilot signals using a pilot basis and treat the associated power coefficients as continuous optimization variables. We compute a lower bound on the uplink capacity for Rayleigh fading channels with maximum ratio detection that applies with arbitrary pilot signals. We further formulate the max-min fairness problem under power budget constraints, with the pilot signals and data powers as optimization variables. Because this optimization problem is non-deterministic polynomial-time hard due to signomial constraints, we then propose an algorithm to obtain a local optimum with polynomial complexity. Our framework serves as a benchmark for pilot design in scenarios with either ideal or non-ideal hardware. Numerical results manifest that the proposed optimization algorithms are close to the optimal solution obtained by exhaustive search for different pilot assignments and the new pilot structure and optimization bring large gains over the state-of-the-art suboptimal pilot design.

  • 3061.
    Van Chien, Trinh
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    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.
    Joint Pilot Sequence Design and Power Control for Max-Min Fairness in Uplink Massive MIMO2017In: IEEE International Conference on Communications (ICC), 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    This paper optimizes the pilot assignment and pilottransmit powers to mitigate pilot contamination in MassiveMIMO (multiple-input multiple-output) systems. While priorworks have treated pilot assignment as a combinatorial problem,we achieve a more tractable problem formulation by directlyoptimizing the pilot sequences. To this end, we compute alower bound on the uplink (UL) spectral efficiency (SE), forRayleigh fading channels with maximum ratio (MR) detectionand arbitrary pilot sequences. We optimize the max-min SEwith respect to the pilot sequences and pilot powers, under powerbudget constraints. This becomes an NP-hard signomial problem,but we propose an efficient algorithm to obtain a local optimumwith polynomial complexity. Numerical results manifest the nearoptimality of the proposed algorithm and show significant gainsover existing suboptimal algorithms.

  • 3062.
    Van Chien, Trinh
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    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.
    Joint Power Allocation and User Association Optimization for Massive MIMO Systems2016In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 15, no 9, p. 6384-6399Article in journal (Refereed)
    Abstract [en]

    This paper investigates the joint power allocationand user association problem in multi-cell Massive MIMO(multiple-input multiple-output) downlink (DL) systems. Thetarget is to minimize the total transmit power consumptionwhen each user is served by an optimized subset of the basestations (BSs), using non-coherent joint transmission. We firstderive a lower bound on the ergodic spectral efficiency (SE),which is applicable for any channel distribution and precodingscheme. Closed-form expressions are obtained for Rayleigh fadingchannels with either maximum ratio transmission (MRT) or zeroforcing (ZF) precoding. From these bounds, we further formulatethe DL power minimization problems with fixed SE constraintsfor the users. These problems are proved to be solvable aslinear programs, giving the optimal power allocation and BS-user association with low complexity. Furthermore, we formulatea max-min fairness problem which maximizes the worst SEamong the users, and we show that it can be solved as aquasi-linear program. Simulations manifest that the proposedmethods provide good SE for the users using less transmit powerthan in small-scale systems and the optimal user associationcan effectively balance the load between BSs when needed.Even though our framework allows the joint transmission frommultiple BSs, there is an overwhelming probability that only oneBS is associated with each user at the optimal solution.

  • 3063.
    Van Chien, Trinh
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    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.
    Multi-Cell Massive MIMO Performance with Double Scattering Channels2016In: Proceedings of IEEE International Workshop on Computer Aided Modelling and Design of Communication Links and Networks (CAMAD) 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 243-248Conference paper (Refereed)
    Abstract [en]

    This paper investigates the spectral efficiency (SE)of multi-cell Massive Multi-Input Multi-Output (MIMO) usingdifferent channel models. Prior works have derived closed form SE bounds and approximations for Gaussian distributedchannels, while we consider the double scattering model—a primeexample of a non-Gaussian channel for which it is intractable toobtain closed form SE expressions. The channels are estimatedusing limited resources, which gives rise to pilot contamination,and the estimates are used for linear detection and to computethe SE numerically. Analytical and numerical examples are usedto describe the key behaviors of the double scattering models,which differ from conventional Massive MIMO models. Finally,we provide multi-cell simulation results that compare the doublescattering model with uncorrelated Rayleigh fading and explainunder what conditions we can expect to achieve similar SEs.

  • 3064.
    Van Chien, Trinh
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    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.
    Le, Tuan Anh
    Department of Design Engineering & Maths, Middlesex University London, United Kingdom.
    Distributed Power Control in Downlink Cellular Massive MIMO Systems2018In: WSA 2018: 22nd International ITG Workshop on Smart Antennas, VDE Verlag GmbH, 2018, p. 1-7Conference paper (Refereed)
    Abstract [en]

    This paper compares centralized and distributed methods to solve the power minimization problem with quality-of-service (QoS) constraints in the downlink (DL) of multi-cell Massive multiple-input multiple-output (MIMO) systems. In particular, we study the computational complexity, number of parameters that need to be exchanged between base stations (BSs), and the convergence of iterative implementations. Although a distributed implementation based on dual decomposition (which only requires statistical channel knowledge at each BS) typically converges to the global optimum after a few iterations, many parameters need to be exchanged to reach convergence.

  • 3065.
    van der Mei, Rob
    et al.
    Centrum Wiskunde and Informatica (CWI), NLD.
    van den Berg, Hans
    TNO, NLD.
    Ganchev, Ivan
    University of Limerick, IRE.
    Tutschku, Kurt Tutschku
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Leitner, Philipp
    University of Zurich, CHE.
    Lassila, Pasi
    Aalto University, FIN.
    Burakowski, Wojciech
    Warsaw University of Technology, POL.
    Liberal, Fidel
    University of the Basque Country (UPV/EHU), ESP.
    Arvidsson, Åke
    Kristianstad University, SWE.
    Hoßfeld, Tobias
    lInstitute of Computer Science and Business Information Systems (ICB), DEU.
    Wac, Katarzyna
    University of Geneva, CHE.
    Melvin, Hugh
    National University of Ireland, IRE.
    Galinac Grbac, Tihana
    University of Rijeka, HRV.
    Haddad, Yoram
    JCT-Lev Academic Center, ISR.
    Key, Peter
    Microsoft Research Ltd., GBR.
    State of the Art and Research Challenges in the Area of Autonomous Control for a Reliable Internet of Services2018In: Autonomous Control for a Reliable Internet of Services: Methods, Models, Approaches, Techniques, Algorithms, and Tools / [ed] Ganchev, Ivan, van der Mei, Robert D., van den Berg, J.L., Springer Publishing Company, 2018Chapter in book (Refereed)
    Abstract [en]

    The explosive growth of the Internet has fundamentally changed the global society. The emergence of concepts like service-oriented architecture (SOA), Software as a Service (SaaS), Platform as a Service (PaaS), Infrastructure as a Service (IaaS), Network as a Service (NaaS) and Cloud Computing in general has catalyzed the migration from the information-oriented Internet into an Internet of Services (IoS). This has opened up virtually unbounded possibilities for the creation of new and innovative services that facilitate business processes and improve the quality of life. However, this also calls for new approaches to ensuring quality and reliability of these services. The goal of this book chapter is to first analyze the state-of-the-art in the area of autonomous control for a reliable IoS and then to identify the main research challenges within it. A general background and high-level description of the current state of knowledge is presented. Then, for each of the three subareas, namely the autonomous management and real-time control, methods and tools for monitoring and service prediction, and smart pricing and competition in multi-domain systems, a brief general introduction and background are presented, and a list of key research challenges is formulated.

  • 3066.
    Van der Perre, Liesbet
    et al.
    Katholieke Univ Leuven, Belgium; Lund Univ, Sweden; Lund Univ, Sweden.
    Liu, Liang
    Lund Univ, Sweden.
    Larsson, Erik G
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Efficient DSP and Circuit Architectures for Massive MIMO: State of the Art and Future Directions2018In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 66, no 18, p. 4717-4736Article in journal (Refereed)
    Abstract [en]

    Massive MIMO is a compelling wireless access concept that relies on the use of an excess number of base-station antennas, relative to the number of active terminals. This technology is a main component of 5G New Radio and addresses all important requirements of future wireless standards: a great capacity increase, the support of many simultaneous users, and improvement in energy efficiency. Massive MIMO requires the simultaneous processing of signals from many antenna chains, and computational operations on large matrices. The complexity of the digital processing has been viewed as a fundamental obstacle to the feasibility of Massive MIMO in the past. Recent advances on system-algorithm-hardware co-design have led to extremely energy-efficient implementations. These exploit opportunities in deeply-scaled silicon technologies and perform partly distributed processing to cope with the bottlenecks encountered in the interconnection of many signals. For example, prototype ASIC implementations have demonstrated zero-forcing precoding in real time at a 55 mW power consumption (20 MHz bandwidth, 128 antennas, and multiplexing of 8 terminals). Coarse and even errorprone digital processing in the antenna paths permits a reduction of consumption with a factor of 2 to 5. This article summarizes the fundamental technical contributions to efficient digital signal processing for Massive MIMO. The opportunities and constraints on operating on low-complexity RF and analog hardware chains are clarified. It illustrates how terminals can benefit from improved energy efficiency. The status of technology and real-life prototypes discussed. Open challenges and directions for future research are suggested.

  • 3067.
    Van, Dung Pham
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Fiorani, Matteo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Resource management for optical interconnects in data centre networks2017In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7842226Conference paper (Refereed)
    Abstract [en]

    This paper deals with resource management in data centre networks that feature optical interconnects. It first proposes an optical resource management framework as a platform to develop different solutions for multipoint-to-multipoint optical communication systems with a centralized controller. The paper takes optical intra-rack communications as an example application scenario of the framework and studies the intra-rack scheduling (IRS) problem using a theoretical approach. The problem is mapped into the classical open-shop scheduling problem, in which the optical interfaces are viewed as the jobs and the wavelengths used for communication among the interfaces are viewed as the machines. The IRS problem can therefore be solved by adopting the existing preemptive and/or non-preemptive open-shop scheduling algorithms. In a realistic intra-rack communication scenario with non-negligible network reconfiguration time, it is important to understand whether the preemptive or non-preemptive strategy provides better performance under given traffic conditions and system configurations. To address the question, this paper presents a performance analysis that allows to quantitatively compare the two scheduling strategies in terms of packet delay and potential energy savings obtained from sleep mode implementation. Analytical results reveal that the non-preemptive strategy outperforms the preemptive one for typical configurations used in data centre networks. In addition, the tuning and wake-up times of optical transceivers are shown to be key performance-determining factors. The proposed framework and obtained findings are not limited to the considered intra-rack communication scenario, but can be applied to any centralized optical switching systems featuring multipoint-to-multipoint transmissions with non-negligible reconfiguration time.

  • 3068.
    Van, Dung pham
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Rimal, B. P.
    Maier, M.
    Fiber optic vs. wireless sensors in energy-efficient integrated FiWi smart grid networks: An energy-delay and TCO comparison2016In: Proceedings - IEEE INFOCOM, IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    This paper aims at designing an ecoconscious future-proof sensor enhanced fiber-wireless (SFiWi) network based on EPON, WLAN, wireless sensor (WS), and fiber optic sensor (FOS) technologies as a shared communications infrastructure for broadband access and smart grids. A total cost of ownership (TCO) model is developed to help utilities decide whether to deploy WSs or FOSs in different scenarios and estimate sensor-related costs. To prolong battery life of wireless devices and maximize the overall energy efficiency, a novel energy conservation scheme for SFiWi networks (ECO-SFiWi) is proposed. ECO-SFiWi designs the whole network in three TDMA layers to enhance network performance, while scheduling network components to sleep outside their transmission slots. A comprehensive energy saving model accounting for both optical backhaul and wireless front-end components and a delay analysis based on M/G/1 queuing are presented. Results reveal that with their extremely long lifetime and ability to sustain in harsh environments, FOSs are superior to WSs when advanced interrogation techniques are deployed to reduce their total cost. ECO-SFiWi achieves more than 89% of energy savings, while maintaining low delay for both broadband and smart grid traffic in typical scenarios. FPGA hardware emulation and analytical results match well verifying the effectiveness of ECO-SFiWi.

  • 3069.
    Van, Dung Pham
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). Institut National de la Recherche Scientifique (INRS), Canada.
    Rimal, Bhaskar Prasad
    Maier, Martin
    Valcarenghi, Luca
    Design, Analysis, and Hardware Emulation of a Novel Energy Conservation Scheme for Sensor Enhanced FiWi Networks (ECO-SFiWi)2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 34, no 5, p. 1645-1662Article in journal (Refereed)
    Abstract [en]

    Fiber-wireless sensor networks (Fi-WSNs) composed of a hybrid fiber-wireless (FiWi) network enhanced with sensors will play a key role in supporting machine-to-machine (M2M) communications to enable a wide range of Internet of Things (IoT) applications, of which smart grids represent an important real-world example. This paper explores opportunities of designing an energy-efficient Fi-WSN based on EPON/10G-EPON, WLAN, wireless sensors, and passive fiber optic sensors as a shared communications infrastructure for broadband services and smart grids. A novel energy conservation scheme for sensor enhanced FiWi networks (ECO-SFiWi) is proposed to reduce the overall energy consumption. ECO-SFiWi maximizes energy efficiency by leveraging TDMA to schedule power-saving modes of EPON's optical network units, wireless stations, and wireless sensors and incorporate them into EPON's bandwidth allocation algorithm. To study the performance, a comprehensive energy saving model and a delay analysis of both FiWi traffic and sensor data based on M/G/1 queue modeling are presented. FPGA-based hardware emulation and demonstration are performed to verify the effectiveness of the proposed solution. Results provide deep insights into the tradeoff between energy savings and frame delays. Noticeably, ECO-SFiWi achieves significant amounts of energy saving, while maintaining low delay for FiWi traffic and sensor data under typical deployment scenarios.

  • 3070.
    Van Kerrebrouck, J.
    et al.
    Univ Ghent, Imec, INTEC, IDLab, Ghent, Belgium..
    Zhang, Lijia
    KTH. KTH Royal Inst Technol, Kista, Sweden.;Shanghai Jiao Tong Univ, SE IEE, Shanghai, Peoples R China..
    Lin, Rui
    KTH.
    Pang, Xiaodan
    KTH. RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Udalcovs, A.
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Ozolins, O.
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Spiga, S.
    Walter Schottky Inst, Coulombwall 4, Garching, Germany..
    Amann, M. C.
    Walter Schottky Inst, Coulombwall 4, Garching, Germany..
    Van Steenberge, G.
    Univ Ghent, Imec, INTEC, CMST, Ghent, Belgium..
    Gan, L.
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Tang, M.
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Fu, S.
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Schatz, Richard
    KTH.
    Popov, Sergei
    KTH.
    Liu, D.
    Huazhong Univ Sci & Technol, Wuhan, Hubei, Peoples R China..
    Tong, W.
    Yangtze Opt Fiber & Cable Joint Stock Ltd Co, Wuhan, Hubei, Peoples R China..
    Xiao, S.
    Shanghai Jiao Tong Univ, SE IEE, Shanghai, Peoples R China..
    Torfs, G.
    Univ Ghent, Imec, INTEC, IDLab, Ghent, Belgium..
    Chen, Jiajia
    KTH.
    Bauwelinck, J.
    Univ Ghent, Imec, INTEC, IDLab, Ghent, Belgium..
    Yin, X.
    Univ Ghent, Imec, INTEC, IDLab, Ghent, Belgium..
    726.7-Gb/s 1.5-mu m Single-Mode VCSEL Discrete Multi-Tone Transmission over 2.5-km Multicore Fiber2018In: 2018 Optical Fiber Communications Conference and Exposition, OFC 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018Conference paper (Refereed)
    Abstract [en]

    A 107Gb/s net-rate DMT optical signal was generated using a single-mode long-wavelength VCSEL with a modulation bandwidth of 23GHz. We experimentally demonstrated a total net-rate up to 726.7Gb/s at 1.5 mu m over 2.5km 7-core dispersion-uncompensated MCF.

  • 3071. Van Kerrebrouck, J.
    et al.
    Zhang, Lu
    KTH, School of Information and Communication Technology (ICT). Shanghai Jiao Tong University, Shanghai, China.
    Lin, Rui
    KTH, School of Information and Communication Technology (ICT). uazhong University of Science and Technology, Wuhan, China.
    Pang, Xiaodan
    Networking and Transmission Laboratory, RISE Acreo AB, Kista, Sweden.
    Udalcovs, A.
    Ozolins, O.
    Spiga, S.
    Amann, M. C.
    Van Steenberge, G.
    Gan, L.
    Tang, M.
    Fu, S.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT).
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT).
    Liu, D.
    Tong, W.
    Xiao, S.
    Torfs, G.
    Chen, Jia
    KTH, School of Information and Communication Technology (ICT).
    Bauwelinck, J.
    Yin, X.
    726.7-Gb/s 1.5-μm single-mode VCSEL discrete multi-tone transmission over 2.5-km multicore fiber2018In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    A 107Gb/s net-rate DMT optical signal was generated using a single-mode longwavelength VCSEL with a modulation bandwidth of 23GHz. We experimentally demonstrated a total net-rate up to 726.7Gb/s at 1.5μm over 2.5km 7-core dispersion-uncompensated MCF.

  • 3072. Van Moer, W.
    et al.
    Barbe, K.
    Björsell, Niklas
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    A novel spectral subtraction technique for cognitive radios2013In: 2013 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), IEEE , 2013, p. 118-121Conference paper (Refereed)
    Abstract [en]

    In the past a lot of work has been done to remove noise from speech. Most of the presented techniques were derived from Boll's spectral subtraction technique. Roughly speaking the spectral subtraction techniques consists of estimating the noise power during the periods when no speech is present and subtracting this estimate of the noise power from the signal when speech is present. This spectral subtraction technique could be a very good in-band de-noising technique for communication signals measured by cognitive radios. However, there is one major drawback: one can never turn off the spectrum so that no communication signals are present. This paper presents an extended version of the spectral subtraction technique which does not require 'speech free' periods, but can determine the noise power from the empty frequency bins in the spectrum. The presented method is based on an autoregressive (AR) model, which is linear in the parameters. Simulation results show that the presented technique is as performing as the original spectral subtraction techniques without the need to turn off the signals. 

  • 3073. Vardakas, J. S.
    et al.
    Monroy, I. T.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Agapiou, G.
    Brenot, R.
    Pleros, N.
    Verikoukis, C.
    Towards high capacity and low latency backhauling in 5G: The 5G STEP-FWD vision2017In: 2017 19th International Conference on Transparent Optical Networks (ICTON), IEEE Computer Society, 2017, article id 8025130Conference paper (Refereed)
    Abstract [en]

    This paper presents the vision of the 5G STEP-FWD project, funded by the European Commission, with the objective to propose a novel optical-wireless networking solution for the provision of high speed connectivity to end users. The features of the new architecture, based on the utilization of Ultra-Dense Wavelength Division Multiplexing Passive Optical Networks as the backhaul network, providing access to hyper dense mmWave networks, are presented in detail. Moreover, the research challenges to meet the 5G requirements in terms of low latency, spectral and energy efficiency are highlighted, followed by the description of way the project 5G STEP-FWD is going to address them.

  • 3074.
    Vargas-Orellana, Julio
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    A Distributed Approach for Global Product Lifecycle Management2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Product Lifecycle Management (PLM) is a holistic approach for managing product information throughout its life cycle. It integrates different concepts that have emerged due to changes in the manufacturing process as a result of globalization, increased competition, demand for more innovative products, and other reasons. These changes have leaded to a shift from a model with a single-location for product development to a model in which a complex network of specialized companies collaborate.

    This global collaborative PLM implies that companies from different parts of the world work together and must share information; hence the underlying PLM system is required to facilitate data management throughout this collaborative process. In addition, it is also necessary to address the challenges due to the new model being a distributed activity, as today this PLM system is a specialized distributed system.

    Maintaining data consistency can be challenging because collaborators can use heterogeneous PLM systems together with their own databases. The later cannot be shared due to the risks of exposing their knowledge base and business processes. Another consideration in global collaboration is that data is transmitted to remote locations. As a result network latency can be large; this can cause problems particularly when large files are exchanged, such as may be the case for CAD design models.

    This thesis proposes a solution enabling a global PLM which addresses the challenges described above. The approach consists of connecting collaborators’ nodes in a network that is constructed by grouping them with respect to intra-site latency. Each group implements a coordination mechanism based on the election of a node which is subsequently in charge of coordinating data access. The groups communicate via a publish-subscribe communication pattern, publishing and subscribing to events related to the resources being shared. The integration of the solution is through a Service-oriented Architecture (SOA) implementing web services that can be consumed by a PLM system. A prototype has been implemented and its applicability is analysed by evaluating its functionality in a collaborative scenario based on the Aras Innovator PLM platform.

    The evaluation was made by simulating the solution proposed and comparing it with a centralized approach. The results particularly showed that the proposed solution could reduce the intra-latency compared to a centralized approach if the collaborators are organized in collaborative groups, that exchange most of the information inside the group rather than intergroup.

  • 3075.
    Varisteas, Georgios
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Effective cooperative scheduling of task-parallel applications on multiprogrammed parallel architectures2015Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Emerging architecture designs include tens of processing cores on a single chip die; it is believed that the number of cores will reach the hundreds in not so many years from now. However, most common parallel workloads cannot fully utilize such systems. They expose fluctuating parallelism, and do not scale up indefinitely as there is usually a point after which synchronization costs outweigh the gains of parallelism. The combination of these issues suggests that large-scale systems will be either multiprogrammed or have their unneeded resources powered off.Multiprogramming leads to hardware resource contention and as a result application performance degradation, even when there are enough resources, due to negative share effects and increased bus traffic. Most often this degradation is quite unbalanced between co-runners, as some applications dominate the hardware over others. Current Operating Systems blindly provide applications with access to as many resources they ask for. This leads to over-committing the system with too many threads, memory contention and increased bus traffic. Due to the inability of the application to have any insight on system-wide resource demands, most parallel workloads will create as many threads as there are available cores. If every co-running application does the same, the system ends up with threads $N$ times the amount of cores. Threads then need to time-share cores, so the continuous context-switching and cache line evictions generate considerable overhead.This thesis proposes a novel solution across all software layers that achieves throughput optimization and uniform performance degradation of co-running applications. Through a novel fully automated approach (DVS and Palirria), task-parallel applications can accurately quantify their available parallelism online, generating a meaningful metric as parallelism feedback to the Operating System. A second component in the Operating System scheduler (Pond) uses such feedback from all co-runners to effectively partition available resources.The proposed two-level scheduling scheme ultimately achieves having each co-runner degrade its performance by the same factor, relative to how it would execute with unrestricted isolated access to the same hardware. We call this fair scheduling, departing from the traditional notion of equal opportunity which causes uneven degradation, with some experiments showing at least one application degrading its performance 10 times less than its co-runners.

  • 3076.
    Varshney, Ambuj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Mottola, Luca
    RISE SICS AB, Sweden and Politecnico di Milano, Italy.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. RISE SICS AB, Sweden.
    Visible Light Communication for Wearable ComputingManuscript (preprint) (Other academic)
    Abstract [en]

    Visible Light Communication (VLC) is emerging as a means to network computing devices that ameliorates many hurdles of radio-frequency (RF) communications, for example, the limited available spectrum. Enabling VLC in wearable computing, however, is challenging because mobility induces unpredictable drastic changes in light conditions, for example, due to reflective surfaces and obstacles casting shadows.We experimentally demonstrate that such changes are so extreme that no single design of a VLC receiver can provide efficient performance across the board. The diversity found in current wearable devices complicates matters. Based on these observations, we present three different designs of VLC receivers that i) are individual orders of magnitude more efficient than the state-of-the-art in a subset of the possible conditions, and ii) can be combined in a single unit that dynamically switches to the best performing receiver based on the light conditions.Our evaluation indicates that dynamic switching incurs minimal overhead, that we can obtain throughput in the order of MBit/s, and at energy costs lower than many RF devices.

  • 3077. Vassilaras, S.
    et al.
    Gkatzikis, Lazaros
    KTH, School of Electrical Engineering (EES), Automatic Control. University of Thessaly, Greece.
    Liakopoulos, N.
    Stiakogiannakis, I. N.
    Qi, M.
    Shi, L.
    Liu, L.
    Debbah, M.
    Paschos, G. S.
    The Algorithmic Aspects of Network Slicing2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 8, p. 112-119, article id 8004165Article in journal (Refereed)
    Abstract [en]

    Network slicing is a technique for flexible resource provisioning in future wireless networks. With the powerful SDN and NFV technologies available, network slices can be quickly deployed and centrally managed, leading to simplified management, better resource utilization, and cost efficiency by commoditization of resources. Departing from the one-Type-fits-All design philosophy, future wireless networks will employ the network slicing methodology in order to accommodate applications with widely diverse requirements over the same physical network. On the other hand, deciding how to efficiently allocate, manage, and control the slice resources in real time is very challenging. This article focuses on the algorithmic challenges that emerge in efficient network slicing, necessitating novel techniques from the communities of operation research, networking, and computer science.

  • 3078.
    Vatn, Jon-Olov
    et al.
    KTH, Superseded Departments, Teleinformatics.
    Maguire Jr., Gerald Q.
    KTH, Superseded Departments, Teleinformatics.
    The Effect of Using Co-Located Care-of Addresses on Macro Handover Latency1998In: 14th Nordic Tele-traffic Seminar, 1998Conference paper (Refereed)
  • 3079. Vazifehdan, Javad
    et al.
    Prasad, Venkatesha
    Jacobsson, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Niemegeers, Ignas
    An analytical energy consumption model for packet transfer over wireless links2012In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 16, no 1, p. 30-33Article in journal (Refereed)
    Abstract [en]

    We provide a detailed analytical model for estimating the total energy consumed to exchange a packet over a wireless link. Our model improves many of the current models by considering details such as consumed energy by processing elements of transceivers,packet retransmission, reliability of links, size of data packets and acknowledgments, and also the data rate of wireless links. To develop the model, we use experimental results based on IEEE 802.15.4 devices to show that consumed energy for receiving erroneous packets is comparable to the consumed energy for receiving error-free packets.

  • 3080. Vega, Maria
    et al.
    Gross, James
    Statistical Analysis of OFDMA Assignments2008In: IEEE International Symposium on Wireless Communication Systems. 2008. ISWCS '08., IEEE conference proceedings, 2008, p. 16-20Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate statistical properties of IP optimal subcarrier assignments in the down-link of an OFDMA cell. Essentially, we show that such subcarrier assignments do have ¿hidden¿ statistical properties which can be exploited to design an extremely simple assignment strategy. We investigate such statistical properties and the corresponding performance of the simple assignment rules regarding a specific, well-known, NP-hard assignment problem. Although our approach is ¿light-weight¿ in complexity, the strategy provides a significant performance gain compared to static assignments. Finally, we investigate our approach also for other optimization problems in the context of multi-user OFDMA assignments.

  • 3081.
    Vega-Barbas, Mario
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Universidad Politécnica de Madrid, Spain.
    Pau, Ivan
    Universidad Politecnica de Madrid.
    Valero, Miguel Angel
    Universidad Politecnica de Madrid.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. University of Borås, Sweden.
    Adaptive Software Architecture for Confident Homecare in the Digital Home2014Conference paper (Refereed)
    Abstract [en]

    Smart spaces foster the development of more natural and suitable forms of human-computer interaction taking advantage of customization possibilities offered by the home. The interaction chances of the Digital Home, as a special type of smart space, have a special interest in fields where the acceptance of new technologies is low and restrictive. Homecare is a discipline where this acceptance is more problematic. The integration of digital home design patterns in homecare solutions should enhance the final acceptance of users. In this position paper, we present the main challenges identified from the literature for the successful implementation of homecare solutions in smart spaces and the design of a software architecture that models entities and functionalities involved in solving these challenges.

  • 3082. Vehkapera, M.
    et al.
    Riihonen, T.
    Girnyk, Maksym
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Björnson, E.
    Debbah, M.
    Kildehøj Rasmussen, Lars
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Wichman, R.
    Asymptotic analysis of asymmetric MIMO links: EVM limits for joint decoding of PSK and QAM2015In: 2015 IEEE International Conference on Communications (ICC), IEEE conference proceedings, 2015, Vol. 2015, p. 1869-1873Conference paper (Refereed)
    Abstract [en]

    Hardware non-idealities in wireless transmitter electronics cause distortion that is not captured by conventional linear channel models; in fact, error-vector magnitude (EVM) measurements in conformance testing conceptually reduce their collective effect to an additive noise component at each subcarrier. Motivated by the EVM, the present paper considers a 'binoisy' multiple-input multiple-output (MIMO) channel model where the additional non-idealities manifest themselves as an additive distortion noise term at the transmit side. Through this extended MIMO relation, the effects of hardware impairments on the achievable rates of different digital modulation schemes are studied via large system analysis. The numerical results illustrate how tolerable EVM levels depend non-trivially on various factors, including the signal-to-noise ratio, modulation order and the level of asymmetry in antenna array configurations.

  • 3083.
    Vehkapera, Mikko
    et al.
    Aalto University, Finland.
    Riihonen, Taneli
    Aalto University, Finland.
    Girnyk, Maksym A.
    KTH Royal Institute Technology, Sweden; KTH Royal Institute Technology, Sweden.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Debbah, Merouane
    Huawei France RandD Centre, France; Supelec, France.
    Kildehoj Rasmussen, Lars
    KTH Royal Institute Technology, Sweden; KTH Royal Institute Technology, Sweden.
    Wichman, Risto
    Aalto University, Finland.
    Asymptotic Analysis of SU-MIMO Channels With Transmitter Noise and Mismatched Joint Decoding2015In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 63, no 3, p. 749-765Article in journal (Refereed)
    Abstract [en]

    Hardware impairments in radio-frequency components of a wireless system cause unavoidable distortions to transmission that are not captured by the conventional linear channel model. In this paper, a "binoisy" single-user multiple-input multiple-output (SU-MIMO) relation is considered where the additional distortions are modeled via an additive noise term at the transmit side. Through this extended SU-MIMO channel model, the effects of transceiver hardware impairments on the achievable rate of multi-antenna point-to-point systems are studied. Channel input distributions encompassing practical discrete modulation schemes, such as, QAM and PSK, as well as Gaussian signaling are covered. In addition, the impact of mismatched detection and decoding when the receiver has insufficient information about the non-idealities is investigated. The numerical results show that for realistic system parameters, the effects of transmit-side noise and mismatched decoding become significant only at high modulation orders.

  • 3084.
    Veillas, Erik
    KTH, Superseded Departments, Teleinformatics.
    Simulations on an IP-based real-time network1998Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The diversity of the communication networks is expanding. At the same time, the frontier between telecommunications and data communications becomes more and more fuzzy. It is already possible to have all kinds of data cohabit in some communication networks. As an example, speech is present in the Internet. This huge patchwork of networks using the IP protocol for the addressing of its hosts is one of the main application fields for IP-telephony, though it is still unsuitable because of its only best effort service. IP-telephony-products have thus to be adapted to these particular conditions and need to be tested accordingly.

    We study here quality of service parameters in an IP-based real-time network simulated with an event-driven packet-level simulator in a large number of configurations. Our results serve in an IP-telephony project to provide miscellaneous realistic IP-telephony product tests. Phenomena characterizing the cohabitation of real-time and best effort traffic are also observed.

  • 3085.
    venkesh, kandari
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Implementation and Performance Optimization of WebRTC Based Remote Collaboration System2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 3086.
    Verdaguer, Sergi Laencina
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Model driven context awareness2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The very nature of mobile phones makes them ideal vehicles to study both individuals and organizations: people habitually carry a mobile phone with them and use it as a medium for much of their communication. The information available from today's phones includes the user's location, people nearby, and communication (call and SMS logs), as well as application usage and phone status (idle, charging, and so on).

    The main goal of this project is to combine some of the new technologies of voice over IP (VoIP) with context awareness services for mobile users and create a demonstrator for a typical routine of a student in Kista.

    We used context awareness together with the SIP Express Router to make a system more intelligent for the user. In this thesis the definition of CPL scripts and how they could exploit context information to provide SIP service that would be useful to a student were examined. A simple test was conducted to measure the overhead of using context awareness by the SIP proxy when processing CPL scripts.

  • 3087. Verenzuela, D.
    et al.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). Freelinguist.com, Sweden.
    Scalable D2D Communications for Frequency Reuse >> 1 in 5G2017In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, no 6, p. 3435-3447, article id 7891615Article in journal (Refereed)
    Abstract [en]

    Proximity-based applications are becoming fast growing markets suggesting that device-to-device (D2D) communications is becoming an essential part of the future mobile data networks. We propose scalable admission and power control methods for D2D communications underlay cellular networks to increase the reuse of frequency resources and thus network capacity while maintaining QoS to all users. In practice, as D2D communications will generate a new layer of interference, it is essential to take D2D interference into account in inter-cell interference coordination for multi-cell communications. The aim of the proposed methods is to maximize the number of D2D links under QoS constraints, therefore maximizing network frequency reuse in a practical 5G multi-cell environment. Different schemes are designed for applications that have different levels of complexity and availability of channel state information. Numerical results show that by using D2D and the proposed multi-cell interference coordination and low power transmission method, the network spectral efficiency can be increased by as much as ten times, while low outage probability can be assured to provide QoS for all users.

  • 3088.
    Verenzuela, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Matthaiou, Michail
    Queen’s University Belfast.
    Hardware Design and Optimal ADC Resolution for Uplink Massive MIMO Systems2016In: IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM), Rio de Janeiro, Brazil, July 2016., 2016, p. 1-5Conference paper (Refereed)
    Abstract [en]

    This work focuses on the hardware design for the efficient operation of Massive multiple-input multiple-output (MIMO) systems. A closed-form uplink achievable data rate expression is derived considering imperfect channel state information (CSI) and hardware impairments. We formulate an optimization problem to maximize the sum data rate subject to a constraint on the total power consumption. A general power consumption model accounting for the level of hardware impairments is utilized. The optimization variables are the number of base station (BS) antennas and the level of impairments per BS antenna. The resolution of the analog-to-digital converter (ADC) is a primary source of such impairments. The results show the trade-off between the number of BS antennas and the level of hardware impairments, which is important for practical hardware design. Moreover, the maximum power consumption can be tuned to achieve maximum energy efficiency (EE). Numerical results suggest that the optimal level of hardware impairments yields ADCs of 4 to 5 quantization bits.

  • 3089.
    Verenzuela, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Matthaiou, Michail
    Queen’s University Belfast.
    Per-antenna hardware optimization and mixed resolution ADCs in uplink massive MIMO2017In: 2017 51st Asilomar Conference on Signals, Systems, and Computers, IEEE conference proceedings, 2017, p. 27-31Conference paper (Refereed)
    Abstract [en]

    Massive multiple-input multiple-output (MIMO) is a key technology for next generation wireless networks that deploys many antennas at the base stations (BSs). This requires low-complexity hardware at each antenna branch that, in turn, increases distortions. This work studies the selection of per-antenna hardware quality in terms of analog-to-digital converters (ADCs) resolution. A new achievable spectral efficiency (SE) expression is derived and majorization theory is used to analyze the order preserving properties of the SE and the power consumption with respect to the per-antenna ADC resolutions. That is, given a fixed sum of ADC resolutions across the antenna array, is it preferable to use an equal-ADC over a mixed-ADC approach? The results show that having equal-resolution ADCs across the antenna array maximizes the SE and minimizes the power consumption.

  • 3090.
    Verenzuela, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Sanguinetti, Luca
    University of Pisa, Pisa, Italy.
    Optimal Design of Wireless Networks for Broadband Access with Minimum Power Consumption2016In: 2016 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE Communications Society, 2016Conference paper (Refereed)
    Abstract [en]

    The continuous rise in wireless data traffic brings forth an increase in power consumption and static users constitute a large fraction of these traffic demands. This work focuses on designing cellular networks to deliver a given data rate per area and user, while minimizing the power consumption. In particular we are interested in optimizing the transmission power, density of access points (APs), number of AP antennas and number of users served in each cell. To this end, we consider a network model based on stochastic geometry and a detailed power consumption model to derive closed form expressions and obtain insights on the interplay of the aforementioned design parameters. The results show that, in contrast with previous works on optimal network design for energy efficiency, having exceedingly high AP density does not bring the most benefits in terms of power savings. Instead the AP density should be chosen according to the area data rate that we want to deliver. In addition numerical results show that the minimum power consumption is obtained in the Massive MIMO regime with many antennas and users per AP.

  • 3091.
    Verenzuela, Daniel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Chang, Liu
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Wang, Lu
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Shi, Lei
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Improving Scalability of Vehicle-to-Vehicle Communication with Prediction-based STDMA2014In: Vehicular Technology Conference (VTC Fall), 2014 IEEE 80th, IEEE conference proceedings, 2014, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Self-organized TDMA (STDMA) has been proposed as a medium access control (MAC) protocol for Vehicle-to-Vehicle (V2V) communication. Although it avoids the unbounded channel access delay faced by other CSMA-based protocols, the reliability in high traffic density is still unsatisfactory for critical road safety applications. This paper introduces an enhanced prediction-based STDMA protocol which utilizes the spatial information available in the messages exchanged for road safety applications. Thus it allocates the radio resources more efficiently and minimizes the mutual interference among different vehicles. The results show that the prediction-based STDMA offers a significant improvement in the scalability and coverage of the V2V communication system for road safety applications with strict reliability requirement. The performance enhancement of the proposed MAC protocol is achieved without adding much complexity to the existing STDMA and it has considerable potential for further improvement.

  • 3092.
    Verenzuela, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Miao, Guowang
    KTH Royal Institute Technology, Sweden; Freelinguist Com, Sweden.
    Scalable D2D Communications for Frequency Reuse 1 in 5G2017In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, no 6, p. 3435-3447Article in journal (Refereed)
    Abstract [en]

    Proximity-based applications are becoming fast growing markets suggesting that device-to-device (D2D) communications is becoming an essential part of the future mobile data networks. We propose scalable admission and power control methods for D2D communications underlay cellular networks to increase the reuse of frequency resources and thus network capacity while maintaining QoS to all users. In practice, as D2D communications will generate a new layer of interference, it is essential to take D2D interference into account in inter-cell interference coordination for multi-cell communications. The aim of the proposed methods is to maximize the number of D2D links under QoS constraints, therefore maximizing network frequency reuse in a practical 5G multi-cell environment. Different schemes are designed for applications that have different levels of complexity and availability of channel state information. Numerical results show that by using D2D and the proposed multi-cell interference coordination and low power transmission method, the network spectral efficiency can be increased by as much as ten times, while low outage probability can be assured to provide QoS for all users.

  • 3093.
    Vergara Alonso, Ekhiotz Jon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Energy Modelling and Fairness for Efficient Mobile Communication2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Energy consumption and its management have been clearly identified as a challenge in computing and communication system design, where energy economy is obviously of paramount importance for battery powered devices. This thesis addresses the energy efficiency of mobile communication at the user end in the context of cellular networks.

    We argue that energy efficiency starts by energy awareness and propose EnergyBox, a parametrised tool that enables accurate and repeatable energy quantification at the user end using real data traffic traces as input. EnergyBox offers an abstraction of the underlying states for operation of the wireless interfaces and allows to estimate the energy consumption for different operator settings and device characteristics. The tool is used throughout the thesis to quantify and reveal inefficient data communication patterns of widely used mobile applications.

    We consider two different perspectives in the search of energy-efficient solutions. From the application perspective, we show that systematically quantifying the energy consumption of design choices (e.g., communication patterns, protocols, and data formats) contributes to a significantly smaller energy footprint. From the system perspective, we devise a cross-layer solution that schedules packet transmissions based on the knowledge of the network parameters that impact the energy consumption of the handset. These attempts show that application level decisions require a better understanding of possible energy apportionment policies at system level.

    Finally, we study the generic problem of determining the contribution of an entity (e.g., application) to the total energy consumption of a given system (e.g., mobile device). We compare the state-of-the-art policies in terms of fairness leveraging cooperative game theory and analyse their required information and computational complexity. We show that providing incentives to reduce the total energy consumption of the system (as part of fairness) is tightly coupled to the policy selection. Our study provides guidelines to select an appropriate policy depending on the characteristics of the system. 

  • 3094.
    Vergara Alonso, Ekhiotz Jon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Exploiting Energy Awareness in Mobile Communication2013Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Although evolving mobile technologies bring millions of users closer to the vision of information anywhere-anytime, device battery depletions hamper the quality of experience to a great extent. The massive explosion of mobile applications with the ensuing data exchange over the cellular infrastructure is not only a blessing to the mobile user, but also has a price in terms of rapid discharge of the device battery. Wireless communication is a large contributor to the energy consumption. Thus, the current call for energy economy in mobile devices poses the challenge of reducing the energy consumption of wireless data transmissions at the user end by developing energy-efficient communication.

    This thesis addresses the energy efficiency of data transmission at the user end in the context of cellular networks. We argue that the design of energy-efficient solutions starts by energy awareness and propose EnergyBox, a parametrised tool that enables accurate and repeatable energy quantification at the user end using real data traffic traces as input. EnergyBox abstracts the underlying states for operation of the wireless interfaces and allows to estimate the energy consumption for different operator settings and device characteristics.

    Next, we devise an energy-efficient algorithm that schedules the packet transmissions at the user end based on the knowledge of the network parameters that impact the handset energy consumption. The solution focuses on the characteristics of a given traffic class with the lowest quality of service requirements. The cost of running the solution itself is studied showing that the proposed cross-layer scheduler uses a small amount of energy to significantly extend the battery lifetime at the cost of some added latency. 

    Finally, the benefit of employing EnergyBox to systematically study the different design choices that developers face with respect to data transmissions of applications is shown in the context of location sharing services and instant messaging applications. The results show that quantifying energy consumption of communication patterns, protocols, and data formats can aid the design of tailor-made solutions with a significantly smaller energy footprint. 

  • 3095.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    EnergyBox: A Trace-driven Tool for Data Transmission Energy Consumption Studies2013In: EE-LSDS 2013, Energy Efficiency in Large Scale Distributed Systems, Springer, 2013, p. 19-34Conference paper (Refereed)
    Abstract [en]

    Although evolving mobile technologies bring millions of users closer to the vision of information anywhere-anytime, device battery depletions hamper the quality of experience to a great extent. We argue that the design of energy-efficient solutions starts by energy-awareness and propose EnergyBox, a tool that provides accurate and repeatable energy consumption studies for 3G and WiFi transmissions at the user end. We recognize that the energy consumption of data transmission is highly dependable on the traffic pattern, and provide the means for trace-based iterative packet-driven simulation to derive the operation states of wireless interfaces. The strength of EnergyBox is that it allows to modularly set the 3G network parameters specified at operator level, the adaptive power save mode mechanism for a WiFi device, and the different power levels of the operation states for different handheld devices. EnergyBox enables efficient energy consumption studies using real data, which complements the device-dependent laborious physical power measurements. Using real application transmission traces, we have validated EnergyBox showing an accuracy range of 94-99% for 3G and 93-99% for WiFi compared to the real measured energy consumption by a 3G modem and a smartphone with WiFi.

  • 3096.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Watts2Share: Energy-Aware Traffic Consolidation2013In: Green Computing and Communications (GreenCom), 2013 IEEE and Internet of Things (iThings/CPSCom), IEEE International Conference on and IEEE Cyber, Physical and Social Computing, IEEE Computer Society, 2013, p. 14-22Conference paper (Refereed)
    Abstract [en]

    Energy consumption is becoming the Achilles' heel of the mobile user quality of experience partly due to undisciplined use of the cellular (3G) transmissions by applications. The operator infrastructure is typically configured for peak performance, whereas during periods of underutilisation the handsets pay the price by staying in high energy states even if each application only uses a fraction of the maximum available bandwidth. In this paper we promote a bi-radio scenario where instead of independently using own cellular connections, several users share a single cellular link offered by one member of a coalition (a rotating aggregator). We present Watts2Share, an architecture for energy-aware traffic consolidation whereby group members' data flows transmitted through a second radio (e.g., WiFi) are aggregated by the aggregator and retransmitted through the cellular link. Through careful and repeatable studies we demonstrate that this scheme saves up to 68% of the total transmission energy in handsets compared to a pure 3G scenario. The studies are based on a wide range of real traffic traces and real cellular operator settings, and further illustrate that this scheme reduces the overall energy by reducing the signalling overhead, as well as extending the lifetime of all handsets.

  • 3097.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Prihodko, Mihails
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Mobile Location Sharing: An Energy Consumption Study2013In: e-Energy '13 Proceedings of the 4th International Conference on Future Energy Systems: Where Energy, Computing and Communication Meet, New York, NY, USA: ACM Press, 2013, p. 289-290Conference paper (Refereed)
    Abstract [en]

    The use of a mobile device's battery for frequent transmissions of position data in a location sharing application can be more expensive than the location retrieval itself. This is in part due to energy-agnostic application development and in part dependent on choice of protocols. This paper studies the lightweight Message Queuing Telemetry Transport protocol (MQTT) as an application layer protocol on top of the third generation cellular communication. The energy efficiency and amount of data generated by the publish/subscribe MQTT protocol is experimentally compared against the Hypertext Transfer Protocol (HTTP), which is currently used in typical location sharing applications.

    The evaluation results indicate that MQTT is a good candidate as a protocol for location sharing. At comparable bandwidth and energy expenses MQTT offers better quality of user experience, since the subscribers are notified at once when the location of some interesting client has changed. Our measurements show that MQTT is more energy-efficient than HTTP in the idle state and when the number of other users with whom the client shares location is low. When the number of users increases beyond 3, HTTP becomes the preferred option in terms of energy efficiency at the cost of a higher notification delay.

  • 3098.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Sanjuan, Joseba
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Kernel Level Energy-Efficient 3G Background Traffic Shaper for Android Smartphones2013Conference paper (Refereed)
    Abstract [en]

    Reducing the energy consumption of wireless devices is paramount to a wide spread adoption of mobile applications. Cellular communication imposes high energy consumption on the mobile devices due to the radio resource allocation, which differs from other networks such as WiFi. Most applications are unaware of the energy consumption characteristics of third generation cellular communication (3G). This makes the background small data transfers of undisciplined applications an energy burden due to inefficient utilisation of resources.

    While several approaches exist to reduce the energy consumption of this best-effort background traffic by means of traffic shaping, we find that they are mostly evaluated with simulations and the actual energy overhead for the traffic shaper itself has not been studied. In order to cover this gap, our work realises an existing energy saving algorithm as a Kernel Level Shaper (KLS) within the Android platform, and measures its energy footprint. The total energy savings of our implementation range from 8% to 58% for emulated real background traffic, that is categorised as best-effort traffic. We further show the implications of running the KLS during live operation of applications as an exploratory study.

  • 3099.
    Ververis, Vassilios
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Security Evaluation of Intel's Active Management Technology2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Intel’s Active Management Technology (AMT) is, a hardware-based platform for remotely managing and securing personal computers out of band. AMT is available in most desktop and notebooks PCs equipped with an Intel Core 2, Centrino, or Centrino 2 processors with support for vPro technology. AMT operates independently of the platform processor and operating system. Remote platform management applications can access AMT securely, even when the platform is turned off, as long as the platform is connected to power supply and to a network. Developers can build applications that utilize AMT using the application programming interface (API) provided by Intel. While this might seem to enable creation of a powerful management tool, a secure infrastructure that is secure against insider and outsider attacks on an enterprise network is difficult. Unfortunately this technology can also potentially be used to create a powerful backdoor that is easily deployed and offers numerous features due to its almost unlimited permissions since the platform can be managed even though it is powered off.

  • 3100.
    Vesterlund, Martin
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Wiklund, Viktor
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Is this your smart phone?: On connecting MAC-addresses to a specific individual using access point data2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context. The potential to track individuals become greater and greater in the society today. We want to develop a method that is easy to understand so more people can participate in the discussion about the collection, and storing, of seemingly non-invasive device data and personal integrity.

    Objectives. In this work we investigate the potential to connect a WiFi enabled device to a known individual by analysing log files. Since we want to keep the method as simple as possible we choose to not use machine learning because this might add unnecessary layers of complexity.

    Methods. The conducted experiments were performed against a test group consisting of six persons. The dataset used consisted of authentication logs from a university WiFi-network collected during a month and data acquired by capturing WiFi-traffic.

    Results. We were able to connect 67% of the targeted test persons to their smart phones and 60% to their laptops.

    Conclusions. In this work we conclude that a device identifier in combination with data that can tie it to a location at a given time is to be seen as sensitive information with regard to personal integrity. We also conclude that it is possible to create and use an easy method to connect a device to a given person.

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