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  • 3001. Tremblay, Christine
    et al.
    Xu, Zhenyu
    Archambault, Emile
    Mantelet, Guillaume
    Chen, Jiajia
    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).
    Belanger, Michel P.
    Littlewood, Paul
    Proposed filterless architecture and control plane for emerging flexible coherent networks2013In: ICTON 2013: 15th International Conference on Transparent Optical Networks, 2013, p. 1-1Conference paper (Refereed)
    Abstract [en]

    Recent developments in coherent modem performance and digital signal processing (DSP) technologies have opened the opportunity for new agile network architectures [1, 2]. The filterless network concept has been proposed in [3] and it is shown that they are more cost-effective and reliable compared to active optical switching networks. Filterless optical networks use broadcast-and-select techniques in which passive non-filtered optical splitters and combiners are used for channel add-drop and fiber link interconnection. Furthermore, DSP-based coherent modems are complementary foundational technologies for flexible optical networking owing to their properties of dynamic impairment compensation, performance monitoring and tuneability. The resulting network architecture makes an attractive candidate solution for flexible optical networking [4]. In this talk, we review the recent progress in filterless optical network design and control [5]ᅵ[7]. In the first part, filterless architectural solutions are proposed for different network topologies and compared to active photonic switching solutions. A cost and performance analysis of filterless network solutions with 1 + 1 optical layer protection is also presented. In the second part, we present a control plane for filterless optical networks and describe its main characteristics through a performance study. Our results show that passive filterless networks can be considered as a cost effective and simpler alternative to active optical switching networks whenever traffic loading is not approaching full network capacity.

  • 3002.
    Trimintzios, Panagiotis
    et al.
    ENISA.
    Holfeldt, Roger
    Secana.
    Koraeus, Mats
    Swedish Defence University, Department of Security, Strategy and Leadership (ISSL), CRISMART (National Center for Crisis Management Research and Training).
    Uckan, Baris
    Secana.
    Gavrila, Razvan
    ENISA.
    Makrodimitris, Georgios
    ENISA.
    Report on Cyber Crisis Cooperation and Management: Comparative study on the cyber crisis management and the general crisis management2015Report (Other (popular science, discussion, etc.))
    Abstract [en]

    The goal of this study is to provide an analysis of cyber crisis management by identifying relations between this emerging field and the better established subject of general crisis management. This includes terminology and key concepts in these fields. This study further seeks to gain knowledge and understanding of the involved actors’ perspectives on the challenges for Cyber Crisis management within the European context.

    The purpose of the study is twofold: to compare concepts from the general crisis management systems with the corresponding systems related to cyber crisis management, and to conduct a conceptual analysis of the language and terminology within these two fields. The primary aim is to analyse the similarities and differences between general and cyber crisis management, employing examples from countries and organizations within the EU.

    Based on interviews with members of key national and EU institutions, and on an analysis of the differences between their practitioner perspectives and the theories of general crisis management, the study arrives at six key areas of recommendations for future activities in the cyber security realm.

  • 3003.
    Trischler, Jakob
    et al.
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Service Research Center (from 2013).
    Lohmann, Gui
    Griffith University, Brisbane, Australia.
    Monitoring quality of service at Australian airports: A critical analysis2018In: Journal of Air Transport Management, ISSN 0969-6997, E-ISSN 1873-2089, Vol. 67, p. 63-71Article in journal (Refereed)
    Abstract [en]

    The quality of service monitoring forms a key element of the current light-handed regulation at Australian airports. The ACCC (Australian Competition and Consumer Commission) evaluates and publicly reports the quality of service levels of the four largest airports on a yearly basis to pressure airports to maintain an acceptable service performance. This article aims to provide an in-depth analysis of the methodology used by the ACCC. This analysis includes a critical review of the methodology based on secondary information in combination with primary research (i.e., data from 21 semi-structured interviews) that considers the current perception of the methodology among key stakeholder groups. The research finds that the methodology used by the ACCC is underpinned by some limitations, putting in question its effectiveness, reliability and validity. Particularly, its weak design does not allow for a comprehensive interpretation of the reported results or a reliable comparison across monitored airports, thus reduces transparency. Stakeholders pointed out that it is not possible to evaluate whether an airport undertakes infrastructure investments that ensure both the efficiency of ongoing airport operations and appropriate levels of service quality. These limitations add to the perception that the ACCC in its current function is not a ‘credible threat’ to airports with market power. Recommendations and future research directions are provided to address the identified limitations.

  • 3004.
    Tsai, Ming-Fong
    et al.
    National Cheng Kung University, Taiwan.
    Chilamkurti, Naveen
    La Trobe University, Melbourne, Australia.
    Shieh, Ce-Kuen
    National Cheng Kung University, Taiwan.
    Vinel, Alexey
    Saint-Petersburg Institute for Informatics and Automation, Russian Academy of Sciences.
    MAC-level Forward Error Correction mechanism for minimum error recovery overhead and retransmission2011In: Mathematical and computer modelling, ISSN 0895-7177, E-ISSN 1872-9479, Vol. 53, no 11-12, p. 2067-2077Article in journal (Refereed)
    Abstract [en]

    Wireless transmission suffers from poor wireless channel conditions, such as high bit error rate and error bursts resulting from channel fading and radio interference. The MAC-level Forward Error Correction (MFEC) mechanism is proposed to solve these problems. The MFEC mechanism cannot only adaptively adjust Forward Error Correction (FEC) redundancy, depending on the network condition, but can also retransmit whole packets even if the error packet includes several bit errors. In this paper, an Adaptive MAC-level FEC (AMFEC) mechanism is proposed to improve wireless transmission quality. The AMFEC mechanism relies on the effective packet loss rate model to dynamically adjust MFEC redundancy in order to minimize error recovery overhead. The AMFEC mechanism will retransmit the error of sub-packets and increase FEC redundancy to reduce transmission redundancy. The AMFEC mechanism not only enhances the quality of wireless transmission but also reduces the overhead of retransmission. The experimental results show the AMFEC mechanism is better than conventional MFEC mechanisms. © 2010 Elsevier Ltd.

  • 3005.
    Tsai, Ming-Fong
    et al.
    National Cheng Kung University, Taiwan.
    Chilamkurti, Naveen
    La Trobe University, Melbourne, Australia.
    Zeadally, Sherali
    University of the District of Columbia, Washington, DC 20008, United States.
    Vinel, Alexey
    Saint-Petersburg Institute for Informatics and Automation, Russian Academy of Sciences.
    Concurrent multipath transmission combining forward error correction and path interleaving for video streaming2011In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 34, no 9, p. 1125-1136Article in journal (Refereed)
    Abstract [en]

    Video streaming is a popular application on next generation networks (NGNs). However, video streaming over NGNs has many challenges due to the high bit error rates of these networks. Forward error correction (FEC) is often applied to improve the quality of video streaming. However, continuous lost packets decrease the recovery performance of FEC protection in NGNs. To disperse continuous lost packets to different FEC blocks, we propose a concurrent multipath transmission that combines FEC with path interleaving. Our proposed control scheme adaptively adjusts the FEC block length and concurrently sends data interleaved over multiple paths. Experimental results with our approach show improved packet loss and signal to noise ratio performance. © 2010 Elsevier B.V. All rights reserved.

  • 3006.
    Tumula, Chaitanya
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Improving 3GPP-LTE Uplink Control Signaling by Repetition Across Frequency Bands2013In: Proceedings of the IEEE International Conference on Communications (ICC), IEEE , 2013, p. 1243-1248Conference paper (Refereed)
    Abstract [en]

    We propose improvements for the physical uplink control channel (PUCCH) format 2 control signaling in 3GPP-LTE systems. These improvements can be useful for low-cost UE design and optimization planned for the future LTE releases. In the proposed method, instead of repeating a single QPSK symbol across the 12 subcarriers in each OFDM symbol of a resource block as done in the current release of the standard, we pick two QPSK symbols from two independent resource blocks and repeat them across 6 subcarriers each. The proposed method has a performance gain of about 5.5 dB and 1.85 dB over the conventional method with one and two receiving antennas at the base station, respectively. These gains can be achieved without the use of any additional transmission power, time-frequency resources or receiver complexity.

    The cell-specific QPSK sequences specified in the standard for PUCCH transmission are chosen according to the conventional repetition across the 12 subcarriers, hence we suggest new cell-specific QPSK sequences which minimize the peak-to-average-power ratio (PAPR) of the PUCCH signal with the proposed method.

  • 3007.
    Tumula, Chaitanya
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Improving 3GPP-LTE Uplink Control Signaling Performance Using Complex-Field Coding2013In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 62, no 1, p. 161-171Article in journal (Refereed)
    Abstract [en]

    We study the uplink control signaling in 3GPP-Long Term Evolution (LTE) systems. Specifically, we propose a precoding method that uses complex-field coding (CFC) to improve the performance of the physical uplink control channel (PUCCH) format 2 control signaling. We derive optimal detectors for both the conventional method and the proposed precoding method for different cases of channel state information (CSI) and noise variance information at the receiver. With a single receive antenna, the proposed method offers significant gains compared to the coding currently used in 3GPP-LTE for all the different scenarios considered in this work. However the gains are relatively less with two receive antennas.

  • 3008.
    Tumula, Chaitanya
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Optimal Power Allocation for Hybrid ARQ with Chase Combining in i.i.d. Rayleigh Fading Channels2013In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 61, no 5, p. 1835-1846Article in journal (Refereed)
    Abstract [en]

    We consider the optimization of Chase combining (CC)-based hybrid-automatic repeat request (HARQ) schemes with a limit on the maximum number of retransmissions. We formulate two optimization problems: (i) minimizing the packet drop probability (PDP) under a total average transmit power constraint, and (ii) minimizing the average transmit power under a fixed PDP constraint. Towards solving these equivalent optimization problems, we provide a closed-form expression for the outage probability of a CC-HARQ scheme. We then show that solving the optimization problems using an exact expression of the outage probability becomes complex with an increase in the maximum number of retransmissions. We propose an alternative approach in which we approximate the optimization problems by using an approximate outage probability expression and formulate the two optimization problems as two equivalent geometric programming problems (GPPs), which can be solved efficiently even for a large limit on the maximum number of retransmissions.

    The results show that the optimal power allocation solution provides significant gains over the equal power allocation solution. For PDP values below 10-3 , the optimal solution provided by the GPP approach has a performance close to that of the solution provided by solving the optimization problem exactly using nonlinear optimization techniques.

  • 3009.
    Tumula V. K., Chaitanya
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    HARQ Systems: Resource Allocation, Feedback Error Protection, and Bits-to-Symbol Mappings2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Reliability of data transmission is a fundamental problem in wireless communications. Fading in wireless channels causes the signal strength to vary at the receiver and this results in loss of data packets. To improve the reliability, automatic repeat request (ARQ) schemes were introduced. However these ARQ schemes suffer from a reduction in the throughput. To address the throughput reduction, conventional ARQ schemes were combined with forward error correction (FEC) schemes to develop hybrid-ARQ (HARQ) schemes. For improving the reliability of data transmission, HARQ schemes are included in the present wireless standards like LTE, LTE-Advanced and WiMAX.

    Conventional HARQ systems use the same transmission power and the same number of channel uses in different ARQ rounds. However this is not optimal in terms of minimizing the average transmit power or the average energy spent for successful transmission of a data packet. We address this issue in the first part of the dissertation, where we consider optimal resource allocation in HARQ systems with a limit on the maximum number of allowed transmissions for a data packet. Specifically, we consider the problem of minimizing the packet drop probability (PDP) under an average transmit power constraint or equivalently minimizing the average transmit power under a fixed PDP constraint. We consider both incremental redundancy (IR)-based and Chase combining (CC)-based HARQ systems in our work. For an IR-HARQ system, for the special case of two allowed transmissions for each packet, we provide a solution for the optimal number of channel uses and the optimal power to be used in each ARQ round. For a CC-HARQ system, we solve the problem of optimal power allocation in i.i.d. Rayleigh fading channels as well as correlated Rayleigh fading channels. For the CC-HARQ case, we also provide a low complexity geometric programming (GP) solution using an approximation of the outage probability expression.

    HARQ systems conventionally use one bit acknowledgement (ACK)/negative ACK (NACK) feedback from the receiver to the transmitter. In the 3GPP-LTE systems, one method for sending these HARQ acknowledgement bits is to jointly code them with the other control signaling information using a specified Reed-Muller code consisting of 20 coded bits. Even though the resources used for sending this control signaling information can inherently provide a diversity gain, the Reed-Muller code with such a short block size is not good at extracting all of the available diversity. To address this issue, in the second part of this dissertation, we propose two new methods: i) based on complex-field coding (CFC), and ii) using repetition across frequency bands, to extract the inherent diversity available in the channel resources and improve the error protection for the HARQ acknowledgement bits along with the other control signaling information. In the second part of the dissertation, we also propose a new signal space diversity (SSD) scheme, which results in transmit signals having constant envelope (CE). The proposed CE-SSD scheme results in a better overall power efficiency due to the reduced back-off requirements on the radio frequency power amplifier. Moreover, the proposed CE-SSD technique can be useful for application scenarios involving transmission of small number of information bits, such as in the case of control signaling information transmission.

    In conventional HARQ systems, during the retransmission phase, the channel resources are exclusively used for the retransmitted data packet. This is not optimal in terms of efficient resource utilization. For efficient utilization of channel resources during the retransmissions, a superposition coding (SPC) based HARQ scheme was proposed in the literature. In an SPC based HARQ system, an erroneous packet is transmitted together with a new data packet by superposition in the Euclidean space. In the final part of this dissertation, we study performance of different bits-to-symbol mappings for such an SPC based HARQ system.

  • 3010.
    Tumula V. K., Chaitanya
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Bits-to-Symbol Mappings for Superposition Coding Based HARQ Systems2013In: Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC), Institute of Electrical and Electronics Engineers (IEEE), 2013, p. 2468-2472Conference paper (Refereed)
    Abstract [en]

    We consider the mapping of bits-to-superimposed constellation symbols in terms of the achievable rate on the channel for the HARQ system using superposition coding as proposed in [2]. We show that using a Gray mapping of bits-to-superimposed constellation symbols has better performance thanthe conventional natural mapping that results from superposition in signal space, for all the values of the superposition ratio. We also show through link-level simulations that the predicted gains in terms of achievable rate can be realized in practice using LDPC codes. Furthermore, we show that the optimal superposition ratio for the Gray mapping case results in conventional higher order constellation symbols after the superposition operation.

  • 3011.
    Tumula V. K., Chaitanya
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Optimal Resource Allocation for IR-HARQ2011In: Proceedings of the IEEE Swe-CTW, 2011, p. 74-79Conference paper (Refereed)
    Abstract [en]

    In this work, we first provide an exact closed-form expression for the packet drop probability (PDP) in incremental redundancy (IR) based hybrid automatic repeat request (HARQ) schemes with a limit on the maximum number of transmissions. In the later part, we extend our work in [5], and consider the optimal resource allocation problem of minimizing the PDP under the constraints of an average transmit power and total number of channel uses. We provide two approaches to solve this optimization problem and compare their performance with the solution given in [5].

  • 3012.
    Tumula V.K., Chaitanya
    et al.
    McGill Univ., Canada.
    Danev, Danyo
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Constant envelope signal space diversity2014In: Proceedings of the 2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), IEEE conference proceedings, 2014, p. 3147-3151Conference paper (Refereed)
    Abstract [en]

    We propose a nonlinear signal space diversity (SSD) precoding techniquethat produces transmit signals that have constant envelope(CE) in discrete time, resulting in low peak-to-average power ratio(PAPR) waveforms after pulse-shape filtering. We propose twomethods for construction of CE signal set. While the proposed CESSDscheme is inferior to the conventional SSD designs in termsof coding gain performance, it performs better in terms of overallpower efficiency because of the reduced back-off requirement of thepower amplifier (PA).

  • 3013.
    Turlikov, Andrey
    et al.
    Department of Information Systems, State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Vinel, Alexey
    Department of Information Systems, State University of Aerospace Instrumentation, Saint-Petersburg, Russia.
    Capacity Estimation of Centralized Reservation-Based Random Multiple-Access System2007In: XI International Symposium on Problems of Redundancy in Information and Control Systems, 2007, p. 154-160Conference paper (Refereed)
    Abstract [en]

    Modification of the basic random multiple-access model for the case of a centralized reservation-based data network is considered. Substance of the modification is the following. The channel time is composed of equal intervals, which are called frames. Each frame consists of some consequent mini-slots for the transmission of requests, used for the channel reservation, and consequent slots for the actual packets transmission. Upper and lower bounds of Tsybakov’s capacity are estimated for the system. Problem of the optimal choice for the numbers of mini-slots and slots per frame is analyzed. It is shown that these values do not depend on the ratio between the duration of request and packet transmission.

  • 3014.
    Turull, Daniel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Network virtualization as enabler for cloud networking2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet has exponentially grown and now it is part of our everyday life. Internet services and applications rely on back-end servers that are deployed on local servers and data centers. With the growing use of data centers and cloud computing, the locations of these servers have been externalized and centralized, taking advantage of economies of scale.

    However, some applications need to define complex network topologies and require more than simple connectivity to the remote sites. Therefore, the network part of cloud computing, what is called cloud networking, needs to be improved and simplified.

    This thesis argues that network virtualization permits to fill the missing gap and we propose a network virtualization abstraction layer to ease the use of cloud networking for the end users. We implement a software prototype of our ideas using OpenFlow. We also evaluate our prototype with state of the art controllers that has similar functionalities for network virtualization.

    A second part of this thesis focuses on developing a tool for performance testing. We have improved the widely used tool pktgen with receiver functionalities. We use pktgen to generate traffic for our experiments with network virtualization.

  • 3015.
    Turull, Daniel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Hidell, Markus
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Sjödin, Peter
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Evaluating OpenFlow in libNetVirt2012In: The 8th Swedish National Computer Networking Workshop 2012 (SNCNW 2012), 2012Conference paper (Refereed)
    Abstract [en]

    LibNetVirt, the library presented and evaluated here, proposes an architecture for a network virtualization abstraction. Network virtualization has been an important research topic for many years but still suffers from the lack of an abstraction level like the one present in virtualization of computing and storage. LibNetVirt is deployed as a library, similar to libvirt in computer virtualization, with a unified interface towards the underlying network specific drivers. The architecture allows management tools to be independent of the underlying technologies. In addition, it enables programmatic and on-demand creation of virtual networks. We have evaluated libNetVirt in an OpenFlow-enabled network in three different tests: the setup time of a flow, the behavior of the system under a Denial of Service attack and the packet losses in high rate UDP flows.

  • 3016.
    Turull, Daniel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Hidell, Markus
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Sjödin, Peter
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    libNetVirt: The network virtualization library2012In: 2012 IEEE International Conference on Communications (ICC), IEEE conference proceedings, 2012, p. 5543-5547Conference paper (Refereed)
    Abstract [en]

    Network virtualization has been an important research topic for many years but still suffers from the lack of an abstraction level like the one present in virtualization of computing and storage. Our work in progress presented here proposes an architecture for such a network virtualization abstraction. It is deployed as a library, similar to libvirt in computer virtualization, with a unified interface towards the underlying network specific drivers. The architecture will allow management tools to be independent of the underlying technologies. In addition, it will enable programmatic and on-demand creation of virtual networks. A common set of calls is defined to instantiate different virtual networks, using a single node view to provide the user with a suitable abstraction of the network. We describe a prototype of our proposed architecture on top of an OpenFlow-enabled network. We demonstrate its feasibility for creating isolated virtual networks in a programmatic and on demand fashion.

  • 3017.
    Turull, Daniel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Hidell, Markus
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Sjödin, Peter
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Performance evaluation of openflow controllers for network virtualization2014In: High Performance Switching and Routing (HPSR), 2014 IEEE 15th International Conference on, IEEE conference proceedings, 2014, p. 50-56Conference paper (Refereed)
    Abstract [en]

    This paper investigates OpenFlow performance, focusing on how the delay between switch and OpenFlow controller can impact the performance of a network. We use open-source controllers that support network virtualization to evaluate how such delay impacts ICMP, TCP and UDP traffic. We compare the controllers’ flow set-up strategies and we conduct several experiments to compare their TCP and UDP performance. In ad-dition, we introduce a new metric to measure UDP packet losses at the beginning of the flow. The results of the measurements indicate that there are large differences in performance between controllers, and that performance depends on switch-controller delay and flow set-up strategy.

  • 3018.
    Turull, Daniel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Hidell, Markus
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Sjödin, Peter
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Using libNetVirt to control the virtual network2012In: 2012 IEEE 1st International Conference on Cloud Networking (CLOUDNET) (IEEE CloudNet’12), IEEE conference proceedings, 2012, p. 148-152Conference paper (Refereed)
    Abstract [en]

    LibNetVirt proposes an architecture for a network virtualization abstraction using the single node representation model. LibNetVirt is deployed as a library, similar to libvirt in computer virtualization, with a unified interface towards the underlying network specific drivers. The architecture allows management tools to be independent of the underlying technologies. In addition, it enables programmatic and on-demand creation of virtual networks. We have evaluated libNetVirt in an OpenFlow-enabled network in three different tests: the setup time of a flow, the behavior of the system under a Denial of Service attack and the packet losses in high rate UDP flows.

  • 3019.
    Tutschku, Kurt
    Institute of Computer ScienceUniversity of Würzburg, DEU.
    A Measurement-based Traffic Profile of the eDonkey Filesharing Service2004Conference paper (Refereed)
    Abstract [en]

    Peer-to-peer file sharing applications have evolved to one of the major traffic sources in the Internet. In particular, the eDonkey file sharing system and its derivatives are causing high amounts of traffic volume in today’s networks. The eDonkey system is typically used for exchanging very large files like audio/video CDs or even DVD images. In this report we provide a measurement based traffic profile of the eDonkey service. Furthermore, we discuss how this type of service increases the ”mice and elephants” phenomenon in the Internet traffic characteristics.

  • 3020.
    Tutschku, Kurt
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Ahmadi Mehri, Vida
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Carlsson, Anders
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Chivukula, Krishna Varaynya
    CityNetwork Webbhotell AB.
    Johan, Christenson
    CityNetwork Webbhotell AB.
    On Resource Description Capabilities of On-Board Tools for Resource Management in Cloud Networking and NFV Infrastructures2016In: 2016 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC), 2016, p. 442-447Conference paper (Refereed)
    Abstract [en]

    The rapid adoption of networks that are based on "cloudification" and Network Function Virtualisation (NFV) comes from the anticipated high cost savings of up to 70% in their build and operation. The high savings are founded in the use of general standard servers, instead of single-purpose hardware, and by efficiency resource sharing through virtualisation concepts. In this paper, we discuss the capabilities of resource description of "on-board" tools, i.e. using standard Linux commands, to enable OPEX savings. We put a focus on monitoring resources on small time-scales and on the variation observed on such scales. We introduce a QoE-based comparative concept that relates guest and host views on "utilisation" and "load" for the analysis of the variations. We describe the order of variations in "utilisation" and "load" by measurement and by graphical analysis of the measurements. We do these evaluations for different host operating systems and monitoring tools.

  • 3021.
    Tutschku, Kurt Tutschku
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Ahmadi Mehri, Vida
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Carlsson, Anders
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Towards Multi-layer Resource Management in Cloud Networking and NFV Infrastructures2016Conference paper (Refereed)
    Abstract [en]

    Cloud Networking (CN) and related conceptsoffer appealing novelties to Cloud Computing (CC) customers.They can do a one-stop-shopping for network-enhanced cloudservices. In addition, the costs of such services might below due to multiple customers sharing the infrastructures.Moreover, telecommunication network operators are adopt-ing the CN in theirNetwork Functions Virtualisation (NFV)framework for reducing costs and increasing the flexibility oftheir networks. The technical appeal of CN comes from thetight integration of CC and smart networks. The economicalattractiveness results from avoiding dedicated hardware, shar-ing of resources, and simplified resource management (RM) asseen by the users respectively by the applications. The visionof cheap and integrated CN services is obviously attractive,but it is also evident that it will require more complex RMprocedures for efficiently balancing the usage of all resources.In this contribution, we suggest an initial architecture forintegrated and practical RM in CN and NFV systems. TheRM concept aims at locating and analysing performancebottlenecks, efficiency problems, and eventually discover un-used resources. The suggested architecture is based on alayered view on the system. Moreover, we detail difficultiesin practical resources usage monitoring which, in turn, definerequirements for a RM architecture. The requirement analysisis based on measurements in a CN infrastructure.

  • 3022.
    Tutschku, Kurt Tutschku
    et al.
    Universität Wien, AUT.
    Zinner, Thomas
    University of Wuerzburg.
    Nakao, Akihiro
    University of Tokyo.
    Tran-Gia, Phuoc
    University of Wuerzburg.
    Network Virtualization: Implementation Steps Towards the Future Internet.2009In: Workshop on Overlay and Network Virtualization at KIVS 2009, 2009Conference paper (Refereed)
    Abstract [en]

    In this paper we will investigate why and how Network Virtualization (NV) can overcome the shortfalls of the current system and how it paves the way for the Future Internet. Therefore, we will first discuss some major deficiencies and achievements of today’s Internet. Afterwards, we identify three major building blocks of NV: a) the use of application-specific routing overlays, b) the safe consolidation of resources by OS virtualization on a generic infrastructure, and c) the exploitation of the network diversity for performance enhancements and for new business models, such as the provisioning of intermediate nodes or path oracles. Subsequently, we discuss an implementation scheme for network virtualization or routing overlays based on one-hop source routers (OSRs). The capabilities of the combination of NV and OSRs are demonstrated by a concurrent multipath transmission (CMP) mechanism (also known as stripping) for obtaining high throughput transmission pipes. The suggested stripping mechanism constitutes a first instance of a refinement of the concept of NV, the idea of transport system virtualization.

  • 3023.
    Tzanakaki, Anna
    et al.
    Univ Athens, Athens 15772, Greece..
    Wosinska, Lena
    KTH.
    Schares, Laurent
    IBM Corp, Yorktown Hts, NY 10598 USA..
    Liu, Hong
    Google, Mountain View, CA 94043 USA..
    Simeonidou, Dimitra
    Univ Bristol, Bristol BS8 1TH, Avon, England..
    Special Issue on Optical Data Center Networks2018In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 10, no 7, p. ODC1-ODC3Article in journal (Other academic)
    Abstract [en]

    To support the current trends in cloud, Internet of Things, 5G, etc., massive amounts of data need to be processed and stored with very different performance requirements in terms of capacity, granularity, delay, etc. These requirements drive the need for both mega-size data centers (DCs) and distributed micro DCs interconnected with high-speed communication links. This special issue focuses on the key role of optical networking in meeting these requirements through high-capacity, energy-efficient, and flexible connectivity, and presents recent advancements in DC architectures, network solutions, and optical technologies needed to interconnect computing and storage resources within and between DCs.

  • 3024. Tzanakaki, Anna
    et al.
    Wosinska, Lena
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Schares, Laurent
    Liu, Hong
    Simeonidou, Dimitra
    Special Issue on Optical Data Center Networks2018In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 10, no 7, p. ODC1-ODC3Article in journal (Refereed)
    Abstract [en]

    To support the current trends in cloud, Internet of Things, 5G, etc., massive amounts of data need to be processed and stored with very different performance requirements in terms of capacity, granularity, delay, etc. These requirements drive the need for both mega-size data centers (DCs) and distributed micro DCs interconnected with high-speed communication links. This special issue focuses on the key role of optical networking in meeting these requirements through high-capacity, energy-efficient, and flexible connectivity, and presents recent advancements in DC architectures, network solutions, and optical technologies needed to interconnect computing and storage resources within and between DCs.

  • 3025. Tärneberg, William
    et al.
    Mehta, Amardeep
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Wadbro, Eddie
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Eker, Johan
    Kihl, Maria
    Elmroth, Erik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Dynamic application placement in the Mobile Cloud Network2017In: Future generations computer systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 70, p. 163-177Article in journal (Refereed)
    Abstract [en]

    To meet the challenges of consistent performance, low communication latency, and a high degree of user mobility, cloud and Telecom infrastructure vendors and operators foresee a Mobile Cloud Network that incorporates public cloud infrastructures with cloud augmented Telecom nodes in forthcoming mobile access networks. A Mobile Cloud Network is composed of distributed cost- and capacityheterogeneous resources that host applications that in turn are subject to a spatially and quantitatively rapidly changing demand. Such an infrastructure requires a holistic management approach that ensures that the resident applications’ performance requirements are met while sustainably supported by the underlying infrastructure. The contribution of this paper is three-fold. Firstly, this paper contributes with a model that captures the cost- and capacity-heterogeneity of a Mobile Cloud Network infrastructure. The model bridges the Mobile Edge Computing and Distributed Cloud paradigms by modelling multiple tiers of resources across the network and serves not just mobile devices but any client beyond and within the network. A set of resource management challenges is presented based on this model. Secondly, an algorithm that holistically and optimally solves these challenges is proposed. The algorithm is formulated as an application placement method that incorporates aspects of network link capacity, desired user latency and user mobility, as well as data centre resource utilisation and server provisioning costs. Thirdly, to address scalability, a tractable locally optimal algorithm is presented. The evaluation demonstrates that the placement algorithm significantly improves latency, resource utilisation skewness while minimising the operational cost of the system. Additionally, the proposed model and evaluation method demonstrate the viability of dynamic resource management of the Mobile Cloud Network and the need for accommodating rapidly mobile demand in a holistic manner.

  • 3026. Tärneberg, William
    et al.
    Papadopoulos, Alessandro V.
    Mehta, Amardeep
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Kihl, Maria
    Distributed Approach to the Holistic Resource Management of a Mobile Cloud Network2017In: 2017 IEEE 1st International Conference on Fog and Edge Computing (ICFEC), 2017, p. 51-60Conference paper (Refereed)
    Abstract [en]

    The Mobile Cloud Network is an emerging cost and capacity heterogeneous distributed cloud topological paradigm that aims to remedy the application performance constraints imposed by centralised cloud infrastructures. A centralised cloud infrastructure and the adjoining Telecom network will struggle to accommodate the exploding amount of traffic generated by forthcoming highly interactive applications. Cost effectively managing a Mobile Cloud Network computing infrastructure while meeting individual application's performance goals is non-trivial and is at the core of our contribution. Due to the scale of a Mobile Cloud Network, a centralised approach is infeasible. Therefore, in this paper a distributed algorithm that addresses these challenges is presented. The presented approach works towards meeting individual application's performance objectives, constricting system-wide operational cost, and mitigating resource usage skewness. The presented distributed algorithm does so by iteratively and independently acting on the objectives of each component with a common heuristic objective function. Systematic evaluations reveal that the presented algorithm quickly converges and performs near optimal in terms of system-wide operational cost and application performance, and significantly outperforms similar naïve and random methods.

  • 3027.
    Tölli, Antti
    et al.
    University of Oulu.
    Komulainen, Petri
    University of Oulu.
    Boccardi, Federico
    Alcatel-Lucent.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Osseiran, Afif
    Ericsson.
    Multiuser MIMO Systems2011In: Mobile and Wireless Communications for IMT-Advanced and Beyond / [ed] A. Osseiran, J. Montserrat, W. Mohr, John Wiley & Sons, 2011, p. 89-120Chapter in book (Refereed)
    Abstract [en]

    In Multiple Input Multiple Output (MIMO) communications, multiple antenna elements are employed both in the transmitter and the receiver, in order to obtain increased data rates or improved reliability compared to single-antenna transmission. In cellular systems, the Base Stations (BS) may operate in Single User (SU)-MIMO mode, i.e. to employ point-to-point transmission of data just for one multi-antenna User Equipment at a time. Alternatively, the BS can perform Multiuser (MU)-MIMO transmission, i.e. spatially multiplex data streams intended for different UEs that may be equipped with arbitrary numbers of antenna elements. The use of MU-MIMO mode offers potential system capacity gains especially when the BS employs a large antenna array. This chapter discusses various aspects of MIMO communications, with a special focus on the downlink direction of cellular systems. First, an overview of the fundamentals and existing techniques is given. Then, the MIMO related standards and standardization activities are described. Finally, some recent advances concerning MU-MIMO communications are addressed.

  • 3028.
    Törnqvist, Tobias
    KTH, Superseded Departments, Teleinformatics.
    Grafisk logghantering av elektronisk post1995Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Ericsson has for many years, allowed communication between ECN (Ericsson Corporate Network)and Internet. Many applications have been developed for this purpose. When the traffic has increased, the treatment and the control of the statistics in the e-mail logs has been suffering.

    I have, for my Degree Project, developed a system to improve the control and overview of the e-mailtraffic on Ericsson. The statistics are given from Ericssons MAILGATE, which controls the communication by e-mail in and out from Ericsson. The system should give Ericsson a summary of only the relevant data needed for keeping good control.

    The system is using available programs and functions such as; Procmail, XmGr, ImageMagic, Ghostscript, Netscape, etc. It has two main Perl-scripts MAIL_STAT.PL and MAIL_GRAPH.PL that connect and prepare data for the functions. The statistic arrives by e-mail and is then calculated, summarized and shown both as numbers and in graphical plots.

    This report will show some of the methods used and explain some of the choices made to build this e-mailcontrolling system. It will also include a short Userguide and the code for the programs made.

  • 3029.
    Törnroth, Jonas
    KTH, Superseded Departments, Teleinformatics.
    A Server Based Wireless Wallet Enabling Secure PaymentTransactions2000Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At present there is a desire from content providers and merchants for a mechanism that would allow them to enhance trade over the World Wide Web. Security issues inhibit the development of e-commerce hence a secure and user accepted payment service would be embraced.

    This paper introduces a solution for how secure payment transactions can be made. The server based wireless wallet is presented as a solution by which the user could replace his wallet with a SIM Application Toolkit enabled cellular phone. The wireless wallet constitutes the central part of an e-commerce gateway, which enables the application to provide secure sessions between the Mobile Station and the wireless wallet. It consists of a Wireless Internet Gateway, Transport Server and the wireless wallet. A Wireless Internet Browser stored on the SIM makes secure payment transactions possible. This browser includes a security plug-in enabling encryption on the SIM.

    The wireless wallet concept is realized and verified by a demonstration implementation and an analysis on what would be required from a live system.

    The conclusions drawn from this analysis will be that it is technically feasible to deploy the wireless wallet however before this can be done further security enhancements are needed.

    This work has been conducted at Across Wireless AB.

  • 3030.
    Udalcovs, Aleksejs
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Bobrovs, V.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Power efficiency of WDM networks using various modulation formats with spectral efficiency limited by linear crosstalk2014In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 318, p. 31-36Article in journal (Refereed)
    Abstract [en]

    Small channel spacing in WDM systems offers very good spectral efficiency, but may reduce the transparent optical reach because of interchannel crosstalk. In turn, an increase in the network power consumption can be expected, due to the need for signal regeneration. This paper explores the trade-off between spectral efficiency, transparent optical reach, and power consumption. The results confirm that using the most energy efficient transponder (i.e., in terms of W/bps) does not always guarantee the lowest overall network power consumption. This is especially true over long point-to-point distances (i.e., multiple transmission fiber spans) where, in order to ensure stringent quality of transmission levels together with high spectral efficiency, the optical signal needs to be regenerated many times.

  • 3031. Udalcovs, Aleksejs
    et al.
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Bobrovs, Vjaceslavs
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ivanovs, Girts
    Spectral and energy efficiency considerations in mixed-line rate WDM networks with signal quality guarantee2013In: ICTON 2013: 15th International Conference on Transparent Optical Networks, 2013, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Mixed-Line Rate (MLR) is a cost efficient solution to cope with the rapidly increasing and heterogeneous Internet traffic. In a MLR-based scenario wavelength channels are organized in groups (i.e., sub-bands), each of which consisting of channels operating at the same rate, e.g., it is possible to have on the same fiber link subbands operating at 10 Gbps, 40 Gbps, and 100 Gbps. In order to increase spectral efficiency one can reduce not only the channel spacing within a sub-band but also the frequency spacing between sub-bands operating at different rates, i.e., the sub-band spacing. On the other hand smaller sub-band spacing may: (i) negatively impact the transparent optical reach of wavelength channels due to the higher inter-channel crosstalk levels, and consequently (ii) increase the network power consumption because of the need of more signal regeneration. This paper aims at assessing the trade-off between spectral efficiency and the power consumption in a WDM transport network, when a certain quality of transmission needs to be guaranteed at the receiving node. This is accomplished by evaluating a number of spectral efficient MLR solutions, where the number of wavelength channels allocated to each sub-band is varied while keeping the required Bit Error Rate (BER) level at the receiving node fixed. Results show that the width of each sub-band plays a central role in determining the power consumption of an end-to-end connection.

  • 3032.
    Uddin, Misbah
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    A Bottom-Up Approach to Real-Time Search in Large Networks and Clouds2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Networked systems, such as telecom networks and cloud infrastructures, generate and hold vast amounts of conguration and operational data. The goal of this work is to make all this data available through a real-time search process named network search , which will enable new real-time management solutions. The thesis contains several contributions towards engineering a network search system. Key elements of our design are a weakly structured information model that includes spatial properties, a query language that supports location- and schema-oblivious search queries, a peer-to-peer architecture, a set of echo protocols for scalable query processing, and an indexing protocol for ecient routing for spatial queries. The data against which network search is performed is maintained in local real-time databases close to the data sources. The design follows a bottom-up approach in the sense that the topology for query routing is constructed from the underlying network topology. We have built a prototype of the system on a cloud testbed and developed applications that use network search functionality. Testbed measurements suggest that it is feasible to engineer a network search system that processes queries at low latency and low overhead and that can scale to 100'000 nodes. Simulation results for spatial queries show that query processing achieves response times and incurs overhead close to an optimal protocol, and that query result remains accurate under signicant churn.

  • 3033.
    Uddin, Misbah
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    Clemm, Alexander
    Cisco Systems, Inc..
    A Bottom-Up Design for Spatial Search in Large Networks and Clouds2016Report (Other academic)
    Abstract [en]

    Information in networked systems often has spatial semantics: routers, sensors, or virtual machines have coordinates in a geographical or virtual space, for instance. In this paper, we propose a design for a spatial search system that processes queries against spatial information which is maintained in local databases inside a large networked system. In contrast to previous works in spatial databases and peer-to-peer designs, our design is bottom-up, which makes query routing network-aware and thus efficient, and which facilitates system bootstrapping and adaptation. Key to our design is a protocol that creates and maintains a distributed index of object locations based on information from local databases and the underlying network topology. The index builds upon minimum bounding rectangles (MBRs) to efficiently encode locations. We present a generic search protocol which is based on an echo protocol and uses the index to prune the search space and perform query routing. The response times of search queries increase with the diameter of the network, which is asymptotically optimal. We study the performance of the protocol through simulation in static and dynamic network environments, for different network topologies, and for network sizes upto 100'000 nodes. In all experiments, the overhead incurred by our protocol lies within thirty percent of a hypothetical optimal protocol. In addition, the protocol provides high accuracy under significant churn.

  • 3034.
    Uddin, Misbah
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Clemm, Alexander
    Cisco Systems, Inc..
    A peer-to-peer design for spatial search system2015Report (Other academic)
    Abstract [en]

    Information in networked systems often has spatial semantics: routers, sensors, or virtual machines have coordinates in a geographical or virtual space, for instance. In this paper, we propose a peer-to-peer design for a spatial search system that processes queries, such as range or nearest-neighbor queries, on spatial information cached on nodes inside a networked system. Key to our design is a protocol that creates a distributed index of object locations and adapts it to object and node churn. The index is build around the concept of minimum bounding rectangle to efficiently encode locations. We present a search protocol, which is based on an echo protocol that prunes the search space and performs query routing. Simulations show the efficiency of the protocol in pruning the search space, thereby reducing the protocol overhead. For many queries, the protocol efficiency increases with the network size and approaches that of an optimal protocol for large systems. The protocol overhead depends on the network topology and is lower if neighboring nodes are spatially close. In contrast to recent works in spatial databases, our design is bottom-up, which makes query routing network-aware and thus efficient in networked systems.

  • 3035.
    Uddin, Misbah
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Clemm, Alexander
    Cisco Systems Inc. .
    A Query Language for Network Search2013In: Proceedings of the 2013 IFIP/IEEE International Symposium on Integrated Network Management, IM 2013, New York: IEEE conference proceedings, 2013, p. 109-117Conference paper (Refereed)
    Abstract [en]

    Network search makes operational data available in real-time to management applications. In contrast to traditional monitoring, neither the data location nor the data format needs to be known to the invoking process, which simplifies application development, but requires an efficient search plane inside the managed system. This paper presents a query language for network search and discusses how search queries can be executed in a networked system. The search space consists of named objects that are modeled as sets of attribute-value pairs. The data model is more general than the relational model, and the query language is more expressive than relational calculus. The paper shows that distributed query processing can be performed using an echo algorithm and that name resolution can be embedded in query processing. Finally, two use cases for network search are presented, one in networking and one in cloud computing, the latter backed up by a prototype implementation.

  • 3036.
    Uddin, Misbah
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Clemm, Alexander
    Cisco Systems Inc..
    Management by Network Search2012Report (Other academic)
    Abstract [en]

    While networked systems hold and generate vast amounts of configuration and operational data, this data is not accessible through a simple, uniform mechanism. Rather, it must be gathered using a range of different protocols and interfaces. Our vision is to make all this data available in a simple format through a realtime search process which runs within the network and aggregates the data into a form needed by applications—a concept we call network search. We believe that such an approach, though challenging, is technically feasible and will enable rapid development of new management applications and advanced network functions. The paper motivates and formulates the concept of network search, compares it to related concepts like web search, outlines a search architecture, describes the design space and research challenges, and reports on a testbed implementation with management applications built for exploratory purposes of this new paradigm.

  • 3037.
    Uddin, Mohammad Misbah
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Miyazawa, M.
    Hayashi, M.
    Graph search for cloud network management2014In: IEEE/IFIP NOMS 2014 - IEEE/IFIP Network Operations and Management Symposium: Management in a Software Defined World, IEEE conference proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    A large part of operational and configuration information in networks and clouds has graph structure, e.g., virtual network topologies, IP flows, communication links of distributed cloud applications. The final objective of this work is to develop a scalable management system that allows real-time management applications, such as network analytics and anomaly detection applications, to search for graph-structured operational information. The paper contains a step towards this objective. The key challenge is to devise an efficient and scalable search process on data that is volatile and distributed across the network infrastructure. Approaches that are currently pursued for distributed graph databases are not applicable in this context. This paper presents design options and possible solutions for engineering a scalable graph search system that supports management applications. It includes a simple information model based on property graphs and a search query language based on keyword search. The architecture of the system centers around a distributed search plane that performs query processing using a network of search nodes. Finally, the paper outlines the design of a search node, which contains a local database that maintains graph partitions.

  • 3038.
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Report on Wireless Vehicular Communications: [VTS News]2012In: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 7, no 3, p. 102-106Article in journal (Other academic)
  • 3039.
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Report on Wireless Vehicular Communications: [VTS News]2012In: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 7, no 3, p. 102-106Article in journal (Other academic)
  • 3040.
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Workshop Report: Wireless Vehicular Communications [Society News]2013In: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 8, no 4, p. 100-104p. 100-104Article in journal (Other academic)
  • 3041.
    Uhlemann, Elisabeth
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS). Mälardalen University, Västerås, Sweden.
    Festag, Andreas
    NEC, Heidelberg, Germany.
    Special section presenting the three best papers from IEEE WiVeC 2013: [From the Guest Editors]2013In: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 8, no 4, p. 18-19p. 18-19Article in journal (Other academic)
  • 3042.
    Umair, Muhammad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Performance Evaluation and Elastic Scaling of an IP Multimedia Subsystem Implemented in a Cloud2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Network (NGN) technology which enables telecommunication operators to provide multimedia services over fixed and mobile networks. All of the IMS infrastructure protocols work over IP which makes IMS easy to deploy on a cloud platform. The purpose of this thesis is to analysis a novel technique of “cloudifying” the OpenIMS core infrastructure. The primary goal of running OpenIMS in the cloud is to enable a highly available and horizontally scalable Home Subscriber Server (HSS). The resulting database should offer high availability, and high scalability.

    The prototype developed in this thesis project demonstrates a virtualized OpenIMS core with an integrated horizontal scalable HSS. Functional and performance measurements of the system under test (i.e. the virtualized OpenIMS core with horizontally scalable HSS) were conducted. The results of this testing include an analysis of benchmarking scenarios, the CPU utilization, and the available memory of the virtual machines. Based on these results we conclude that it is both feasible and desirable to deploy the OpenIMS core in a cloud.

  • 3043.
    Umair, Muhammad
    et al.
    KTH.
    Shahid, W. B.
    Abbasi, M. J.
    Automatic frequency planning and optimization algorithm for cellular networks2012In: Proceedings of the World Congress on Engineering 2012 Volume I & Volume II & Volume III, Newswood Limited , 2012, Vol. 2198, p. 1287-1291Conference paper (Refereed)
    Abstract [en]

    Frequency planning in ever growing cellular networks is an extremely arduous task. Any effort to lay down manual frequency plans promulgates inefficiency in the cellular radio systems. The extensive deployment and penetration of cellular networks necessitate the need to carry out automatic frequency planning. This paper presents a novel and ingenious algorithm for automatic generation and optimization of the frequency plan whereby curtailing the intra-system interference levels within the acceptable ranges of the key performance indicators (KPI’s) defined for any real time cellular network. The automatic frequency planning and optimization has been done using the concept of Inter-Cell Dependency Matrix (ICDM) which contains cell correlations in terms of the affect one cell has on the other primarily with regards to the co-channel interference. The proposed algorithm was simulated in MATLAB. It has been set forth and tested using inputs from live network data. It has been found to satisfy the verifiable network performance metrics.

  • 3044.
    Ur Rahman, Muhammad Mahboob
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Yasmeen, Aneela
    Gross, James
    KTH, School of Electrical Engineering (EES), Communication Theory.
    PHY Layer Authentication via Drifting Oscillators2014In: Global Communications Conference (GLOBECOM), 2014 IEEE, IEEE conference proceedings, 2014, p. 716-721Conference paper (Refereed)
    Abstract [en]

    PHY layer authentication of a wireless sender has gained much interest recently. In this paper, we consider the famous Alice, Bob and Eve model and investigate (for the first time) the feasibility of using time-varying clock offsets for sender-node-authentication at Bob. Specifically, we exploit the fact (and de-facto problem) that clock offset between every node pair is unique; moreover, the two clock offsets between any two node pairs drift independently and randomly over time. Therefore, an explicit mechanism is needed to track the time-varying clock offsets. To this end, we model oscillator drift as brownian motion frequency and phase drift, and present a novel framework which is based on interplay between a hypothesis testing device and a bank of two Kaiman filters; one KF (KFh0) tracks Alice's clock while other KF (KFh1) tracks Eve's clock. Building on aforementioned framework, we then propose a novel sender-node-authentication method (so-called MHF method) by means of which Bob can automatically accept (reject) a received packet if it is sent by Alice (Eve). Finally, simulation results are presented which corroborate the efficiency of the proposed method.

  • 3045.
    ur Rehman Ahsin, Tafzeel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    A Joint Channel-Network Coding Based on Product Codes for the Multiple-Access Relay Channel2012In: ISRN Communications and Networking, ISSN 2090-4355, E-ISSN 2090-4363, Vol. 2012, p. 1-13Article in journal (Refereed)
    Abstract [en]

    The multiple access relay channel with network coding has the potential to achieve diversity and improve coverage of wireless networks. Its network coding scheme provides an extra redundancy that can be used at the receiver to improve the performance of the cooperating users. This paper shows that the combination of channel coding and network coding, in the multiple access relay channel, can be seen as a product code with rows formed by the code-words of the individual channel codes of the users and columns formed by the network coding code-words. This new representation allows the use of any decoding algorithm of product codes at the receiver to decode the information data of the cooperating users. This decoding process is a complete joint channel-network decoding algorithm as it sees the combination of the two coding schemes as a single coding scheme. It also gives the possibility to use network coding schemes more powerful than conventional XOR-based network coding. The obtained results show that the proposed product-based network coding structure can improve the performance of themultiple-access relay channel without reducing its efficiency and allow a very flexible cooperation between the involved users.

  • 3046.
    ur Rehman Ahsin, Tafzeel
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Area energy consumption in cooperative decode and forward (DF) relaying scenarios2011In: European Wireless 2011, 2011, p. 393-400Conference paper (Refereed)
    Abstract [en]

    Energy efficiency in cellular networks has become an important design parameter in recent research works due to the global climate change and growing demand for very high data rates in future cellular systems. In our work, the main objective is to reduce the area energy consumption in a cellular network, for a given average spectral efficiency, in order to realize the green radio transmissions. The energy consumption for different transmission schemes such as direct link, decode and forward (DF) relaying with and without network coding is compared in this regard using a linear power consumption model. The impact of different parameters such as cell radius, the number and position of deployed relays and target spectral efficiency is studied for each transmission scheme. It has been concluded that DF relaying in general, provides moderate power savings as compared to the direct link transmission. Moreover, for a given outage probability, the network coding at the relay extends the cell coverage and provides higher spectral efficiency as compared to the conventional DF relaying and the direct transmission.

  • 3047.
    Urama, Ifeoma Helen
    et al.
    Mälardalen University.
    Fotouhi, Hossein
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Abdellatif, M. M.
    British University in Egypt, Cairo, Egypt.
    Optimizing RPL Objective Function for Mobile Low-Power Wireless Networks2017In: Proceedings - International Computer Software and Applications Conference, IEEE Computer Society , 2017, p. 678-683Conference paper (Refereed)
    Abstract [en]

    Supporting mobility in wireless sensor networks is one of the major requirements for future Internet of Things (IoT) applications. This work focuses on optimizing the objective function of Routing Protocol for Low-power and Lossy Networks (RPL) in mobile applications. RPL routing is the most common standard routing protocol designed for IoT applications. We optimized RPL objective function by combining several RPL parameters, such as (i) Expected Transmission Count (ETX), (ii) number of hops, and (iii) average Received Signal Strength Indicator (RSSI) as inputs in a fuzzy logic model. These parameters are more influenced in mobile applications. We applied the fuzzy decision to the mRPL (a hand-off enabled RPL mechanism). We fine-tuned the weighting scheme by running extensive simulations to achieve reliable data communication. We found that the fuzzy-based hand-off approach provides high reliability by successfully delivering nearly 100% of data packets, while achieving a very short hand-off delay. 

  • 3048.
    Urdiales Delgado, Diego
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Implementation and Evaluation of the Service Peer Discovery Protocol2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This document is the final report of the master's thesis "Implementation and Evuation of the Service Peer Discovery Protocol", carried out at the Center for Wireess Systems, KTH, Stockholm. This thesis addresses the problem of service discovery in peer-to-peer mobile networks by implementing and evaluating a previously designed protocl (the Service Peer Discovery Protocol).

    The main feature of peer-to-peer networks is that users connected to them can communicate directly with each other, without the necessity of interaction via a central point. However, in order for two networks users (ir peers) to communicate, they must have a means to locate and address each other, which is in gernal called a discovery protocol.

    There are many different solutions for discoverying protocols that work efficiently in fixed or slow-moving networks, but full mobility introduces a set of new difficulties for the discovery of peers and their services. The potential changes in location, which can occur very ofter, the changes in IP address that these changes cuase, and roaming between networks of different kinds are good examples of these difficulties.

    To solve these problems, a new Service Peer Discovery Protocol was designed and a test application built. The next step towards the introduction of this protocol was creating a working implementation, setting up a suitable test environment, performing experiments, and evaluating its performance. This evaluation could lead to improvments in the protoocl. The aim of this thesis is to implement and document the Service Peer Discovery Protocol, to carry out measurements of it, to evaluate the efficiency of the protocol, and to suggest ways in which it could be improved.

    The Service Peer Discovery Protocol was found to be well targeted to wireless, peer-to-peer networks, althgouh improvements in the protocol could make it more time and traffic-efficient while maintaining the same level of performance.

  • 3049.
    Usman, Muhammad
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Västberg, Anders
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Edler, Tomas
    Huawei.
    Energy efficient high capacity HETNET by offloading high QoS users through femto2011In: ICON 2011, ISSN 1556-6463, Vol. 2011, p. 19-24Article in journal (Refereed)
    Abstract [en]

    Bandwidth, network performance, QoS and network power consumption are important dilemmas of contemporary telecommunication networks. With ever increasing demand for data services, networks are destined to become denser and more power hungry, essentially increasing the capital and operational expenditure for operators around the world. One of the technological remedies to this situation is heterogeneous networks. In this work, we present a promising attribute of heterogeneous networks by offloading high QoS indoor users through femto. Additionally, we take traffic demand and sparse network deployment into consideration. The traffic demand is expressed in terms of area spectral efficiency and the power consumed in network nodes is expressed in terms of area power consumption [1]. The results suggest that with an increase in femto density the area spectral efficiency of the considered LTE network increases and decreases monotonously for sparse networks. From an operator's point of view, 100% offloading of premium users through femto is energy efficient at all area spectral efficiency targets. From an environmental perspective, 100% offloading of premium users is beneficial at low area spectral efficiency targets, while at high area spectral efficiency targets 40% offloading is energy efficient.

  • 3050.
    Uzuncan, Ezgi
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Hesamzadeh, Mohammad Reza
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Optimal Firm Transmission Access using Chance-Constrained Optimisation for Renewable Integration2015In: 2015 IEEE Power and Energy Society General Meeting, IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    Electricity markets contain many uncertainties such as changes in generation and demand levels. Especially with increasing integration of wind power, uncertainties in generation availability have increased. This increases the network access risk for generators. Therefore, the need for a reliability mechanism for generators has emerged. Firm transmission access is a transmission reliability mechanism for generators. In order to find the optimal firm access for generators, network reliability studies under uncertainties need to be conducted by the network operator. In the literature, deterministic methods have been widely used. Deterministic approaches might lead to sub-optimal results, since they do not consider the likelihood of scenarios. Therefore, this paper proposes a probabilistic approach to estimate the optimal firm transmission access in the presence of wind power and demand uncertainties, through a chance-constrained optimisation model.

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