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  • 151.
    Avni, G.
    et al.
    IST Austria, Klosterneuburg, Austria.
    Goel, S.
    IIT Bombay, Mumbai, India.
    Henzinger, T. A.
    IST Austria, Klosterneuburg, Austria.
    Rodriguez-Navas, Guillermo
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Computing scores of forwarding schemes in switched networks with probabilistic faults2017In: Lecture Notes in Computer Science, Volume 10206, Springer Verlag , 2017, 169-187 p.Conference paper (Refereed)
    Abstract [en]

    Time-triggered switched networks are a deterministic communication infrastructure used by real-time distributed embedded systems. Due to the criticality of the applications running over them, developers need to ensure that end-to-end communication is dependable and predictable. Traditional approaches assume static networks that are not flexible to changes caused by reconfigurations or, more importantly, faults, which are dealt with in the application using redundancy. We adopt the concept of handling faults in the switches from non-real-time networks while maintaining the required predictability. We study a class of forwarding schemes that can handle various types of failures. We consider probabilistic failures. For a given network with a forwarding scheme and a constant ℓ, we compute the score of the scheme, namely the probability (induced by faults) that at least ℓ messages arrive on time. We reduce the scoring problem to a reachability problem on a Markov chain with a “product-like” structure. Its special structure allows us to reason about it symbolically, and reduce the scoring problem to #SAT. Our solution is generic and can be adapted to different networks and other contexts. Also, we show the computational complexity of the scoring problem is #P-complete, and we study methods to estimate the score. We evaluate the effectiveness of our techniques with an implementation.

  • 152.
    Axberg, Stefan
    et al.
    Swedish National Defence College.
    Brynielsson, Joel
    Swedish National Defence College.
    Norsell, Martin
    Swedish National Defence College.
    A Sensor Concept for Superior Surveillance2007In: Proceedings of the Ninth International Symposium on Protection against Chemical and Biological Warfare Agents, 2007Conference paper (Refereed)
    Abstract [en]

    A highly developed aerial surveillance concept is presented. When fully implemented, the outlined surveillance system enhances situational awareness in two ways: it enhances the overall situational awareness in a large, possibly multinational, area and it provides the possibility to gain additional awareness in critical sites. The system is intended to be beneficial within various kinds of crisis management situations, e.g., disaster relief situations, humanitarian crises, chemical discharges, etc. In particular, the combination of large-area coverage with the possibility to instantly gain local situational awareness is believed to allow for pan-European collaboration and interoperability. Another targeted area includes critical ground sites such as ground transportation and infrastructure. The proposed concept uses surveillance at different altitudes and passes on near real-time information to a variety of end users through its embedded sensor and communications architecture.

  • 153.
    Axell, Erik
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Spectrum Sensing Algorithms Based on Second-Order Statistics2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cognitive radio is a new concept of reusing spectrum in an opportunistic manner. Cognitive radio is motivated by recent measurements of spectrum utilization, showing unused resources in frequency, time and space. Introducing cognitive radios in a primary network inevitably creates increased interference to the primary users. Secondary users must sense the spectrum and detect primary users' signals at very low SNR, to avoid causing too much interference.This dissertation studies this detection problem, known as spectrum sensing.

    The fundamental problem of spectrum sensing is to discriminate an observation that contains only noise from an observation that contains a very weak signal embedded in noise. In this work, detectors are derived that exploit known properties of the second-order moments of the signal. In particular, known structures of the signal covariance are exploited to circumvent the problem of unknown parameters, such as noise and signal powers or channel coefficients.

    The dissertation is comprised of six papers, all in different ways related to spectrum sensing based on second-order statistics. In the first paper, we considerspectrum sensing of orthogonal frequency-division multiplexed (OFDM) signals in an additive white Gaussian noise channel. For the case of completely known noise and signal powers, we set up a vector-matrix model for an OFDM signal with a cyclic prefix and derive the optimal Neyman-Pearson detector from first principles. For the case of completely unknown noise and signal powers, we derive a generalized likelihood ratio test (GLRT) based on empirical second-order statistics of the received data. The proposed GLRT detector exploits the non-stationary correlation structure of the OFDM signal and does not require any knowledge of the noise or signal powers.

    In the second paper, we create a unified framework for spectrum sensing of signals which have covariance matrices with known eigenvalue multiplicities. We derive the GLRT for this problem, with arbitrary eigenvalue multiplicities under both hypotheses. We also show a number of applications to spectrum sensing for cognitive radio.

    The general result of the second paper is used as a building block, in the third and fourth papers, for spectrum sensing of second-order cyclostationary signals received at multiple antennas and orthogonal space-time block coded (OSTBC) signals respectively. The proposed detector of the third paper exploits both the spatial and the temporal correlation of the received signal, from knowledge of the fundamental period of the cyclostationary signal and the eigenvalue multiplicities of the temporal covariance matrix.

    In the fourth paper, we consider spectrum sensing of signals encoded with an OSTBC. We show how knowledge of the eigenvalue multiplicities of the covariance matrix are inherent owing to the OSTBC, and propose an algorithm that exploits that knowledge for detection. We also derive theoretical bounds on the performance of the proposed detector. In addition, we show that the proposed detector is robust to a carrier frequency offset, and propose another detector that deals with timing synchronization using the detector for the synchronized case as a building block.

    A slightly different approach to covariance matrix estmation is taken in the fifth paper. We consider spectrum sensing of Gaussian signals with structured covariance matrices, and propose to estimate the unknown parameters of the covariance matrices using covariance matching estimation techniques (COMET). We also derive the optimal detector based on a Gaussian approximation of the sample covariance matrix, and show that this is closely connected to COMET.

    The last paper deals with the problem of discriminating samples that containonly noise from samples that contain a signal embedded in noise, when the variance of the noise is unknown. We derive the optimal soft decision detector using a Bayesian approach. The complexity of this optimal detector grows exponentially with the number of observations and as a remedy, we propose a number of approximations to it. The problem under study is a fundamental one andit has applications in signal denoising, anomaly detection, and spectrum sensing for cognitive radio.

  • 154.
    Axell, Erik
    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.
    Multiantenna Spectrum Sensing of a Second-Order Cyclostationary Signal2011In: Proceedings of the 4th IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP'11), 2011, 329-332 p.Conference paper (Refereed)
    Abstract [en]

    We consider spectrum sensing of a second-order cyclostationary signal receivedat multiple antennas. The proposed detector exploits both the spatial andthe temporal correlation of the received signal, from knowledge of thefundamental period of the cyclostationary signal and the eigenvaluemultiplicities of the temporal covariance matrix. All other parameters, suchas the channel gains or the noise power, are assumed to be unknown. The proposeddetector is shown numerically to outperform state-of-the-art detectors forspectrum sensing of anOFDM signal, both when using a single antenna and with multiple antennas.

  • 155.
    Axelsson, Andreas
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Ambrosius, Christian
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Nya lagar och avtal: Hur kan de komma att förändra svenskarnas fildelningsvanor?2012Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [sv]

    I många år nu har det varit vanligt förekommande att människor suttit hemma vid sin dator och med några få klick laddat ner filmer, musik och programvaror, till en början helt lagligt, men med åren har lagar kommit till som har gjort det mer och mer olagligt.Oavsett om det har varit lagligt eller inte, så är det troligt att många artister, filmmakare och liknande gått miste om stora summor pengar i förlorade inkomster på grund av att folk inte har betalat för att ta del av deras verk, utan istället valt att ladda ner dem över Internet.

    Det faktum att fildelning har blivit så pass vanligt och att folk inte har sett det som ett särskilt allvarligt brott, har lett till att fildelning länge har varit ett hett omdiskuterat ämne i media, bland upphovsrättsinnehavare och bland folk i allmänhet. Upphovsmän och upphovsrättsinnehavare, såsom filmbolag, författare och artister har legat på och debatterat för att försöka få till en hårdare lagstiftning för att försvåra fildelning och kopiering av upphovsrättsskyddat material, samt för att få till hårdare straff mot fildelning.

    Flera försök från beslutsfattare har gjorts för att råda bot på problemet, nya lagar har stiftats och avtal har skrivits under. Frågan är om de nya lagarna och avtalen gör någon nytta? Blir folk avskräckta från att fildela eller fortsätter de som förut? Många har säkert under många år blivit bortskämda med att kunna sitta hemma vid datorn och på några minuter få hem de senaste filmerna och den nyaste musiken helt gratis, vilket säkert gör det svårt att helt plötsligt sluta fildela och börja betala för film och musik igen.

  • 156.
    Axelsson, Johannes
    Linnaeus University, Faculty of Technology, Kalmar Maritime Academy.
    WAN-optimering för sjöfarten: En möjlighet att effektivisera datakommunikationen till sjöss2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Shipboard operations have become more reliant of data communication and many of the duties on board may be facilitated if the crew can access information stored elsewhere. The broadband connection between ship and shore is mostly done via satellite communication where long distances and limited data rate results in inefficient data communication. This study examines network optimization and the performance improvement this can have regarding slow WAN connections via satellite. The survey showed that the biggest issue with data communication via satellite is the signal delay caused by the long transmission distance which means that there will be performance degradation for data traffic and users will experience the data communication as slow. To solve this there is equipment that enhances the performance of the connection and handles the data communication by implementing various techniques. To investigate how much the performance improvement can be this study carried out a number of experiments with network optimization equipment.  The experiments evaluated file transfer with and without network optimization. The results show that the network optimization gives a major performance improvement regarding file transfer.

  • 157.
    Ayrault, Cécile
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Service discovery for Personal Area Networks2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the increasing use of electronic devices, the need for affordable wireless services specifically context-aware services, in a so-called Personal Area Network (PAN) is becoming an area with significant potential. Service discovery is a basic function.

    Even though a number of service discovery protocols have been implemented, a specific protocol for a PAN environment may need to be developed, as the characteristics of a PANs differ from other networking environments. Thus, the specific requirements for service discovery from a PAN perspective were studied. Methods for service discovery will be described that take into account both local and remote services.

    These methods will then be evaluated in a SIP telephony infrastructure to decide where a call should be delivered. The location of a person is done by using the implemented service discovery.

  • 158.
    Ayyagari, Nitin Reddy
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Databases For Mediation Systems: Design and Data scaling approach2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Context: There is continuous growth in data generation due to wide usage of modern communication systems. Systems have to be designed which can handle the processing of these data volumes efficiently. Mediation systems are meant to serve this purpose. Databases form an integral part of the mediation systems. Suitability of the databases for such systems is the principle theme of this work.

    Objectives: The objective of this thesis is to identify the key requirements for databases that can be used as part of Mediation systems, gain a thorough understanding of various features, the data models commonly used in databases and to benchmark their performance.

    Methods: Previous work that has been carried out on various databases is studied as a part of literature review. Test bed is set up as a part of experiment and performance metrics such as throughput and total time taken were measured through a Java based client. Thorough analysis has been carried out by varying various parameters like data volumes, number of threads in the client etc.

    Results: Cassandra has a very good write performance for event and batch operations. Cassandra has a slightly better read performance when compared to MySQL Cluster but this differentiation withers out in case of fewer number of threads in the client.

    Conclusions: On evaluation of MySQL Cluster and Cassandra we conclude that they have several features that are suitable for mediation systems. On the other hand, Cassandra does not guarantee ACID transactions while MySQL Cluster has good support. There is need for further evaluation on new generation databases which are not mature enough as of now.

  • 159.
    Azari, Amin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy Efficient Machine-Type Communications over Cellular Networks: A Battery Lifetime-Aware Cellular Network Design Framework2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Internet of Things (IoT) refers to the interconnection of uniquely identifiable smart devices which enables them to participate more actively in everyday life. Among large-scale applications, machine-type communications (MTC) supported by cellular networks will be one of the most important enablers for the success of IoT. The existing cellular infrastructure has been optimized for serving a small number of long-lived human-oriented communications (HoC) sessions, originated from smartphones whose batteries are charged in a daily basis. As a consequence, serving a massive number of non-rechargeable machine-type devices demanding a long battery lifetime is a big challenge for cellular networks.

    The present work is devoted to energy consumption modeling, battery lifetime analysis, and lifetime-aware network design for massive MTC services over cellular networks. At first, we present a realistic model for energy consumption of machine devices in cellular connectivity, which is employed subsequently in deriving the key performance indicator, i.e. network battery lifetime. Then, we develop an efficient mathematical foundation and algorithmic framework for lifetime-aware clustering design for serving a massive number of machine devices. Also, by extending the developed framework to non-clustered MTC, lifetime-aware uplink scheduling and power control solutions are derived. Finally, by investigating the delay, energy consumption, spectral efficiency, and battery lifetime tradeoffs in serving coexistence of HoC and MTC traffic, we explore the ways in which energy saving for the access network and quality of service for HoC traffic can be traded to prolong battery lifetime for machine devices.

    The numerical and simulation results show that the proposed solutions can provide substantial network lifetime improvement and network maintenance cost reduction in comparison with the existing approaches.

  • 160.
    Azari, Amin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy-efficient scheduling and grouping for machine-type communications over cellular networks2016In: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 43, 16-29 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, energy-efficient scheduling for grouped machine-type devices deployed in cellular networks isinvestigated. We introduce a scheduling-based cooperation incentivescheme which enables machine nodes to organize themselveslocally, create machine groups, and communicate through grouprepresentatives to the base station. This scheme benefits from anovel scheduler design which takes into account the cooperationlevel of each node, reimburses the extra energy consumptionsof group representatives, and maximizes the network lifetime.As reusing cellular uplink resources for communications insidethe groups degrades the Quality of Service (QoS) of theprimary users, analytical results are provided which present atradeoff between maximum allowable number of simultaneouslyactive machine groups in a given cell and QoS of the primaryusers. Furthermore, we extend our derived solutions for theexisting cellular networks, propose a cooperation-incentive LTEscheduler, and present our simulation results in the context ofLTE. The simulation results show that the proposed solutionssignificantly prolong the network lifetime. Also, it is shown thatunder certain circumstances, reusing uplink resource by machinedevices can degrade the outage performance of the primary userssignificantly, and hence, coexistence management of machinedevices and cellular users is of paramount importance for nextgenerations of cellular networks in order to enable group-basedmachine-type communications while guaranteeing QoS for theprimary users.

  • 161.
    Azari, Amin
    et al.
    Wireless Multimedia Communications Laboratory, Center of Excellence on Applied Electromagnetic Systems, University of Tehran, Iran .
    Harsini, Jalil
    Lahouti, Farshad
    Performance Analysis of Ad-Hoc Routing in Heterogeneous Clustered Multi-hop Wireless Networks2015In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 80, 144-154 p.Article in journal (Refereed)
    Abstract [en]

    This paper analyzes the performance of clustered decode-and-forward multi-hop relaying (CDFMR) wireless Rayleigh fading networks, and sheds light on their design principles for energy and spectral efficiency. The focus is on a general performance analysis (over all SNR range) of heterogeneous wireless networks with possibly different numbers of relays in clusters of various separations. For clustered multi-hop relaying systems, hop-by-hop routing is known as an efficient decentralized routing algorithm which selects the best relay node in each hop using local channel state information. In this article, we combine hop-by-hop routing and cooperative diversity in CDFMR systems, and we derive (i) a closed-form expression for the probability distribution of the end-to-end SNR at the destination node; (ii) the system symbol error rate (SER) performance for a wide class of modulation schemes; and (iii) exact analytical expressions for the system ergodic capacity, the outage probability and the achievable probability of the SNR (power) gain. We also provide simple analytical asymptotic expressions for SER and the outage probability in high SNR regime. Numerical results are provided to validate the correctness of the presented analyses.

  • 162.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Battery Lifetime-Aware Base Station Sleeping Control with M2M/H2H Coexistence2016In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2016, 7841624Conference paper (Refereed)
    Abstract [en]

    Fundamental tradeoffs in green cellular networkswith coexistence of machine-oriented and human-oriented trafficsare investigated. First, we present a queuing system to modelthe uplink transmission of a green base station which servestwo types of distinct traffics with strict requirements on delayand battery lifetime. Then, the energy-lifetime and energydelaytradeoffs are introduced, and closed-form expressions forenergy consumption of the base station, average experienceddelay in data transmission, and expected battery lifetime ofmachine devices are derived. Furthermore, we extend the derivedresults to the multi-cell scenario, and investigate the impacts ofsystem and traffic parameters on the energy-lifetime and energydelaytradeoffs using analytical and numerical results. Numericalresults show the impact of energy saving for the access network onthe introduced tradeoffs, and figure out the ways in which energycould be saved by compromising on the level of performance.

  • 163.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Energy Efficient MAC for Cellular-Based M2M Communications2014In: Signal and Information Processing (GlobalSIP), 2014 IEEE Global Conference on, IEEE conference proceedings, 2014, 128-132 p.Conference paper (Refereed)
    Abstract [en]

    In Machine-to-Machine (M2M) networks, an energyefficient scalable medium access control (MAC) is crucial forserving massive battery-driven machine-type devices. In thispaper, we investigate the energy efficient MAC design to minimizebattery power consumption in cellular-based M2M communications.We present an energy efficient MAC protocol that notonly adapts contention and reservation-based protocols for M2Mcommunications in cellular networks, but also benefits frompartial clustering to handle the massive access problem. Then weinvestigate the energy efficiency and access capacity of contentionbasedprotocols and present an energy efficient contention-basedprotocol for intra-cluster communication of the proposed MAC,which results in huge power saving. The simulation results showthat the proposed MAC protocol outperforms the others in energysaving without sacrificing much delay or throughput. Also, thelifetimes of both individual nodes and the whole M2M networkare significantly extended.

  • 164.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Fundamental Tradeoffs in Resource Provisioning forIoT Services over Cellular Networks2017In: Proceedings of the 2017 IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers (IEEE), 2017, 7996885Conference paper (Refereed)
    Abstract [en]

    Performance tradeoffs in resource provisioningfor mixed internet-of-things (IoT) and human-orientedcommunications(HoC) services over cellular networks are investigated.First, we present a low-complexity model of cellularconnectivity in the uplink direction in which both accessreservation and scheduled data transmission procedures areincluded. This model is employed subsequently in derivinganalytical expressions for energy efficiency, spectral efficiency,and experienced delay in data transmission of connected devicesas well as energy consumption of base stations. The derivedexpressions indicate that the choice of uplink resource provisioningstrategy introduces tradeoffs between battery lifetime forIoT communications, quality of service (QoS) for HoC, spectralefficiency and energy consumption for the access network. Then,the impacts of system and traffic parameters on the introducedtradeoffs are investigated. Performance analysis illustrates thatimproper resource provisioning for IoT traffic not only degradesQoS of high-priority services and decreases battery lifetime ofIoT devices, but also increases energy consumption of the accessnetwork. The presented analytical and simulations results figureout the ways in which spectral/energy efficiency for the accessnetwork and QoS for high-priority services could be traded toprolong battery lifetimes of connected devices by compromisingon the level of provisioned radio resources.

  • 165.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Lifetime-Aware Scheduling and Power Control for Cellular-based M2M Communications2015In: Wireless Communications and Networking Conference (WCNC), 2015 IEEE: , IEEE conference proceedings, 2015, 1171-1176 p.Conference paper (Refereed)
    Abstract [en]

    In this paper the uplink scheduling and transmit powercontrol is investigated to minimize the energy consumption forbattery-driven devices deployed in cellular networks. A lifetimemetric based on the accurate energy consumption model for cellularbasedmachine devices is provided and used to formulate theuplink scheduling and power control problems as network lifetimemaximization problems. Then, lifetime-aware uplink scheduling andpower control protocols which maximize the overall network lifetimeare investigated based on the different lifetime definitions. Besidesthe exact solutions, the low-complexity suboptimal solutions arepresented in this work which can achieve near optimal performancewith much lower computational complexity. The performance evaluationshows that the network lifetime is significantly extended underproposed protocols.

  • 166.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Lifetime-Aware Scheduling and Power Control for M2M Communications in LTE Networks2015In: Vehicular Technology Conference (VTC Spring), 2015 IEEE 81st, IEEE conference proceedings, 2015Conference paper (Refereed)
    Abstract [en]

    In this paper the scheduling and transmit powercontrol are investigated to minimize the energy consumptionfor battery-driven devices deployed in LTE networks. To enableefficient scheduling for a massive number of machine-typesubscribers, a novel distributed scheme is proposed to let machinenodes form local clusters and communicate with the base-stationthrough the cluster-heads. Then, uplink scheduling and powercontrol in LTE networks are introduced and lifetime-aware solu-tions are investigated to be used for the communication betweencluster-heads and the base-station. Beside the exact solutions,low-complexity suboptimal solutions are presented in this workwhich can achieve near optimal performance with much lowercomputational complexity. The performance evaluation showsthat the network lifetime is significantly extended using theproposed protocols.

  • 167.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Network Life time Maximization for Cellular-Based M2M Networks2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, 18927-18940 p.Article in journal (Refereed)
    Abstract [en]

    High energy efficiency is critical for enabling massive machine-type communications (MTC) over cellular networks. This paper is devoted to energy consumption modeling, battery lifetime analysis, lifetime-aware scheduling, and transmit power control for massive MTC over cellular networks. We consider a realistic energy consumption model for MTC and model network battery-lifetime. Analytic expressions are derived to demonstrate the impact of scheduling on both the individual and network battery lifetimes. The derived expressions are subsequently employed in the uplink scheduling and transmit power control for mixed-priority MTC traffic in order to maximize the network lifetime. Besides the main solutions, low complexity solutions with limited feedback requirement are investigated, and the results are extended to existing LIE networks. In addition, the energy efficiency, spectral efficiency, and network lifetime tradeoffs in resource provisioning and scheduling for MTC over cellular networks are investigated. The simulation results show that the proposed solutions can provide substantial network lifetime improvement and network maintenance cost reduction in comparison with the existing scheduling schemes.

  • 168.
    Azari, Amin
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Network Lifetime Maximization for Cellular-Based M2M Networks2017In: IEEE Access, E-ISSN 2169-3536Article in journal (Refereed)
    Abstract [en]

    High energy efficiency is critical for enabling massivemachine-type communications (MTC) over cellular networks.This work is devoted to energy consumption modeling,battery lifetime analysis, lifetime-aware scheduling and transmitpower control for massive MTC over cellular networks. Weconsider a realistic energy consumption model for MTC andmodel network battery-lifetime. Analytic expressions are derivedto demonstrate the impact of scheduling on both the individualand network battery lifetimes. The derived expressions aresubsequently employed in uplink scheduling and transmit powercontrol for mixed-priority MTC traffic in order to maximizethe network lifetime. Besides the main solutions, low-complexitysolutions with limited feedback requirement are investigated,and the results are extended to existing LTE networks. Also,the energy efficiency, spectral efficiency, and network lifetimetradeoffs in resource provisioning and scheduling for MTC overcellular networks are investigated. The simulation results showthat the proposed solutions can provide substantial networklifetime improvement and network maintenance cost reductionin comparison with the existing scheduling schemes.

  • 169.
    Azfar, Abdullah
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Multiple Escrow Agents in VoIP2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Using a Key escrow agent in conjunction with Voice over IP (VoIP) communication ensures that law enforcements agencies (LEAs) can retrieve the session key used to encrypt data between two users in a VoIP session. However, the use of a single escrow agent has some drawbacks. A fraudulent request by an evil employee from the LEA can lead to improper disclosure of a session key. After the escrow agent reveals the key this evil person could fabricate data according to his/her needs and encrypt it again (using the correct session key). In this situation the persons involved in the communication session can be accused of crimes that he or she or they never committed. The problems with a single escrow agent becomes even more critical as a failure of the escrow agent can delay or even make it impossible to reveal the session key, thus the escrow agent might not be able to comply with a lawful court order or comply with their escrow agreement in the case of data being released according to this agreement (for example for disaster recovery).

    This thesis project focused on improving the accessibility and reliability of escrow agents, while providing good security. One such method is based on dividing the session key into M chunks and escrowing the chunks with M escrow agents. Using threshold cryptography the key can be regenerated by gathering any N-out-of-M chunks. The value of M and N may differ according to the role of the user. For a highly sophisticated session, the user might define a higher value for M and N for improved, availability, reliability, and security. For a less confidential or less important session (call), the value of M and N might be smaller. The thesis examines the increased availability and increased reliability made possible by using multiple escrow agents.

  • 170.
    Azzolin de Carvalho Pires, Gustavo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Multi-Cell Admission Control for WCDMA Networks2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It has long been recognized that in multi-cell WCDMA networks the admission of a new session into the system can have undesirable impact on the neighboring cells. Although admission control algorithms that take into account such multi-cell impact have been studied in the past, little attention has been paid to multi-cell admission and rate control algorithms when traffic is elastic. In this thesis, we propose a model for multi-cell multi-service WCDMA networks to study the impact of multi-cell admission and rate control algorithms on key performance measures such as the class-wise blocking and outage probabilities, block error rates, and the noise rise violation probabilities. By means of simulation we compare the performance of load based multi-cell algorithms with that of a single cell algorithm. We find that with multi-cell based algorithms the system capacity and performance (in terms of the above mentioned measures) are (in some cases significantly) better in homogeneous load scenarios as well as in the heterogeneous ’hotspot’ and ’hotaround’ scenarios.

  • 171.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Spectral Efficient and Fair User Pairing for Full-Duplex Communication in Cellular Networks2016In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 15, no 11, 7578-7593 p.Article in journal (Refereed)
    Abstract [en]

    —A promising new transmission mode in cellular networks is the three-node full-duplex mode, which involves a base station with full-duplex capability and two half-duplex user transmissions on the same frequency channel for uplink and downlink. The three-node full-duplex mode can increase spectral efficiency, especially in the low transmit power regime, without requiring full-duplex capability at user devices. However, when a large set of users is scheduled in this mode, self-interference at the base station and user-to-user interference can substantially hinder the potential gains of full-duplex communications. This paper investigates the problem of grouping users to pairs and assigning frequency channels to each pair in a spectral efficient and fair manner. Specifically, the joint problem of user uplink/downlink frequency channel pairing and power allocation is formulated as a mixed integer nonlinear problem that is solved by a novel joint fairness assignment maximization algorithm. Realistic system level simulations indicate that the spectral efficiency of the users having the lowest spectral efficiency is increased by the proposed algorithm, while a high ratio of connected users in different loads and self-interference levels is maintained.

  • 172. Babaheidarian, P.
    et al.
    Salimi, S.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Preserving confidentiality in the Gaussian broadcast channel using compute-and-forward2017In: 2017 51st Annual Conference on Information Sciences and Systems, CISS 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, 7926077Conference paper (Refereed)
    Abstract [en]

    We study the transmission of confidential messages across a wireless broadcast channel with K > 2 receivers and K helpers. The goal is to transmit all messages reliably to their intended receivers while keeping them confidential from the unintended receivers. We design a codebook based on nested lattice structure, cooperative jamming, lattice alignment, and i.i.d. coding. Moreover, we exploit the asymmetric compute-and-forward decoding strategy to handle finite SNR regimes. Unlike previous alignment schemes, our achievable rates are attainable at any finite SNR value. Also, we show that our scheme achieves the optimal sum secure degrees of freedom of 1 for the K-receiver Gaussian broadcast channel with K confidential messages and K helpers.

  • 173.
    Babu, Bibin
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Connected Me: Hardware for high speed BCC2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Body coupled communication (BCC) is a hot topic in personal networking domain. Many works arepublished suggesting different architectures for BCC since its inception in 1995 by Zimmerman. The number ofelectronic gadgets used by a single person increases as time pass by. Its a tedious job to transfer data betweenthen from a user point of view. Many of these gadgets can share their resources and save power and money.The existing wired or wireless networks does not meet the requirements for this network like scalable data rate,security etc. So here comes the novel idea of using human body as communication medium. The aim of thisthesis is to realize a hardware for BCC based on wide band signaling as part of a big project.The human body consists of 70% of water. This property makes the human body a fairly good conductor.By exploiting this basic property makes the BCC possible. A capacitance is formed if we place a metal platenear to the human body with the skin as a dielectric. This capacitance forms the interface between the humanbody and the analog front-end of the BCC transceiver. Any other metal structures near to the human body canattenuate the signal.A first-order communication link is established in software by the human body model and the transceiver inthe loop along with noise and interference. This communication link is used to verify the human body modeland the base band model done as part of the same big project. Based on the results a hardware prototype isimplemented. Measurements are taken in different scenarios using the hardware setup. The trade-off betweendesign parameters are discussed based on the results. At the end, it suggests a road map to take the projectfurther.

  • 174.
    Backlund, Ola
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Policy-based IP services over UMTS2001Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Providing services over IP with real-time characteristics are one of the challenges that the next generation UMTS operators arefacing. Offering these services with adequate quality will be an important task in the management of their networks, which to alarge extent will be built on IP technology. Policy-based network management is an approach to improving network performanceand QoS. This is a network management model, suitable for highlevel service management that has been proposed as a promisingsolution for dynamic QoS. It is well suited for networks with hierarchical service models, which is the situation encountered inUMTS.

    The aim of this Master thesis is to examine IP services providedover UMTS based on the ideas from policy-based network technology and how they can be applied to this next generation ofcellular systems. A framework for policy-based QoS management support is outlined for the packet domain of UMTS, which is basedon the principles and experience derived from policy-based network technology found in fixed networks. A description of thefunctions and capabilities of a policy-based management system designed for UMTS is given, and the QoS related problems inUMTS are identified in order to evaluate the bottlenecks for improving service quality. The report ends with a proposal to howTelia may provide UMTS access to a IP access node that is currently being tested and developed in co-operation with othermanufacturers. Two possible solutions are described and evaluated from a QoS and architectural perspective.

  • 175.
    Badinson (nee Hossieni), David
    KTH, Superseded Departments, Teleinformatics. KTH, School of Information and Communication Technology (ICT).
    Adding Gigabit Ethernet to an ATM Switch1999Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This document contains the outcome of the final version of my thesis project: Adding Gigabit Ethernet access to an ATM switch. The accelerating growth of LAN (Local Area Network) traffic and growing number of complex and bandwidth hungry applications, such as, fast Interent, video telephony, voice over Internet, etc., is pushing  network administrators to look to high-speed network technologies.

    The Gigabit Ethernet and ATM are two dominant technologies in network backbone which are operating at gigabit-speed. These two technologies are considered to be competitors, but in reality they are appropriate for different applications and they are not equal substitute for each other. What we can do in this connection is to take up the advantages of both technologies and try to on somehow integrate them, in order to achieve high performance and powerful networks which are extremely demanded for future applications.

    The purpose with this project was to study the ATM and Gigabit Ethernet technologies and investigate the possibility of integrating them. This report includes an introduction to both technologies and design for a Gigabit Ethernet access card to an ATM switch. The document presents the including components in the card and gives a detailed description for each of components.

  • 176.
    Baecklund, Fredrik
    KTH, Superseded Departments, Teleinformatics.
    Software architecture for a scalable carrier class edge router1999Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the rapid growth of the Internet in the recent years and the expected future growth puts greater demands on high performance access and routing  technologies. The Ericsson AXI 510 Edge Router is a step in the right direction but to provide enough performance for future demands, a highly scalable system has to be designed. This new system is probably going to be based on a distributed architecture.

    In this MSc thesis the author discusses possible ways of designing a scalable distributed edge router software architecture and what implications the distributed architecture has on different edge router applications such as Network Address Translation, tunnel termination and management etc. Furthermore, the author presents a design proposal for a fully distributed architecture.

  • 177.
    Baetens, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Improving the Quality of Web Content through Automated Metrics: An attempt to process course pages at the kth.se website2015Report (Other (popular science, discussion, etc.))
    Abstract [en]

    Today many organizations make a great deal of content available via a web interface. For this project the main scope will be the public web of KTH Royal Institute of Technology. KTH has lots of data available online. The problem that occurs is that the people who write this content do not get feedback about what they post. The idea of this project is to change that and by giving the responsible person(s) feedback about their content.

    The main goal of the project is keeping track of changes of web pages. For example, each course has its own content and information pages - which can be changed by the person(s) responsible for the course. When pages are available in two languages and changes are made to one of them the logical expectation would be that the other language has to be changed as well. However, in the current system there is no systematic way that this change occurs or that someone would be reminded when only one version changed. Similarly for other content pages, although these might not be in multiple languages it would be interesting to see how often a page is updated and to notify the responsible person(s) that a certain page has not been updated in quite some time.

    A secondary goal of this project is to provide a proof of concept implementation of a tool that can automatically access web page in KTH Social (a locally developed web service) – thus enabling users to write code that can access, modify, and annotate web pages. Such a tool could be used to compute readability scores for each page and then annotate the page with this score.

    The code that was implemented for this project accomplished both goals. Some suggestions are made for how this process can be improved and how alternatively this processing could be done by working directly on the databases used to produce dynamic content.

  • 178.
    Bagci, Ibrahim
    et al.
    Lancaster University.
    Raza, Shahid
    SICS.
    Chung, Antony
    Univ. of Lancaster.
    Roedig, Utz
    Univ. of Lancaster.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Combined Secure Storage and Communication for the Internet of Things2013In: IEEE International Conference on Sensing, Communication and Networking (IEEE SECON), 2013Conference paper (Refereed)
  • 179. Bagger, Reza
    Noise reduction and tilt reduction in passive FET multi-phase mixers2012Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The noise response in a passive mixer circuit is improved by discharging the switching transistors in the mixer circuit in an appropriate time slot prior to activation. In addition to improving the noise response, tilt in conversion gains and linearity can be reduced. A passive mixer circuit includes bypass switches arranged in proximity to the switching transistors that make up the mixer core. These bypass switches, which are activated in intervals just prior to the active intervals of their neighboring switching transistors, discharge to ground accumulated charges on the switching transistors or on reactive components around switches.

  • 180.
    Bagger, Reza
    et al.
    Infineon Technology Nordic AB, Kista, Sweden.
    Hahn, T
    Wallace, R
    Edevarn, L
    System-in-package synthesizer for PCS/DCS application2007In: European Microwave Week 2007 Conference Proceedings, IEEE , 2007, 520-523 p.Conference paper (Refereed)
    Abstract [en]

    The article presents a system-in-package (SiP) approach for synthesizer system module used in frequency down-and up-conversion of PCS/DCS radio base station applications using low-temperature co-fired ceramic (LTCC). The hybrid module benefits from the latest qualified production technology based on multilayer LTCC technology. LTCC permits a relatively high level of circuit integration in which different parts of the synthesizer such as the VCO, buffer amplifier, loop filter, PLL circuit, switch, and voltage regulator are integrated in a single substrate of 21 x 16 x 4 mm3. The module exhibits minimum RF tuning sections, improved performance repeatability, excellent RF performance, and good low phase noise. The module covers 1800 MHz Rx/Tx and 1900 MHz Rx/Tx frequency bands. Adoption of the synthesizer to upper or lower frequency band is possible by means of few component changes in a novel tuneable resonator structure. The module's design concept defines 4 commercial products which is included in Infineon's portfolio of wireless infrastructure circuit solutions for PCS/DCS radio basestation applications.

  • 181. Bagger, Reza
    et al.
    Sahl, Stefan
    Signal generator and associated phase shift apparatus and method2013Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    It is presented a signal generator for providing a first signal on a first output and a second signal on a second output wherein the first signal and the second signal are provided with phase shift relative to each other. The signal generator comprises: a control loop controller; a comparator; a phase shifter, the phase shifter being arranged to provide the first signal on the first output and the second signal on the second output; and a phase error detector, the inputs of which are connected to the outputs of the phase shifter and the output of which is connected to an input of the control loop controller. The output of the control loop controller is connected in a feedback loop to a first input of the comparator, and a second input of the comparator is arranged to be connected to an alternating current source.

  • 182. Bagger, Reza
    et al.
    Wallace, Richard
    Hahn, Tobias
    Palima, Dante
    Resonator for a voltage controlled oscillator and manufacturing method thereof2007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    An LC resonator (117; 122) for a voltage controlled oscillator (13; 116) has an inductive transmission line 31; 51), and input and output ports (33 a-b; 53 a-b) connected to the transmission line, wherein the transmission line is grounded (G) in at least one end portion thereof. The inductive transmission line has a plurality of connection ports (P) that are capable of being connected to each other or to ground in order to tune the resonance frequency of the LC resonator from one frequency band to another. Further, a trimming capacitor (C) may be interconnected in the transmission line in order to further tune the resonance frequency of the LC resonator. Preferably, the LC resonator is formed as a microstrip or strip line structure in essentially a C or S shape on a laminate substrate (101-103).

  • 183.
    Baglee, David
    et al.
    Department of Computing, Engineering and Technology, University of Sunderland, UK.
    Gorostegui, Unai
    Mondragon Unibertsitatea.
    Jantunen, Erkki
    VTT Technical Research Centre of Finland.
    Campos, Jaime
    LNU.
    Sharma, Pankaj
    Indian Institute of Technology Delhi.
    Optimizing Condition Monitoring of Big Data Systems2017In: Proceedings of the 2017 International Conference on Data Mining / [ed] Robert Stahlbock, Mahmoud Abou-Nasr, Gary M. Weiss, 2017, 127-131 p.Conference paper (Refereed)
  • 184.
    Baglee, David
    et al.
    Department of Computing, Engineering and Technology, University of Sunderland, UK.
    Gorostegui, Unai
    Mondragon University, Spain.
    Jantunen, Erkki
    VTT Technical Research Centre of Finland.
    Sharma, Pankaj
    Indian Institute of Technology, India.
    Campos, Jaime
    LNU.
    How can SMEs adopt a new method to advanced maintenance strategies:  A Case study approach2017In: 30th International Congress & Exhibition on Condition Monitoring and Diagnostic Engineering Management COMADEM, July 10th-13th 2017, University of Central Lancashire, 2017Conference paper (Refereed)
  • 185.
    Bai, Xin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Broadband Wireless Access in Disaster Emergency Response2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The “WLAN in Disaster Emergency Response” (WIDER) project has developed and implemented an emergency communication system. It provides network and communication services to relief organizations. In order to guarantee the stable and efficient connectivity with a high quality of service (QoS) for the end user, and to make the WIDER system more adaptive to the disaster area, the IEEE 802.16 specification based broadband wireless access solution is adopted. This thesis work aims at evaluating and testing the WIDER system integrated with WiMAX. By learning and analyzing the technology, the benefits and perspective for WIDER using WiMAX are described. A WiMAX solution was configured and integrated into the WIDER system. A series of tests and measurements provide us the performance of the WiMAX solution in throughput, QoS, and reality. The tests helped us to learn and verify the improvements for WIDER due to WiMAX.

  • 186.
    Baig, Roger
    et al.
    Fundacio Privada per la Xarxa Lliure, Oberta i Neural Guifi.net. Mas l’Esperanca, 08503 Gurb, Catalonia.
    Freitag, Felix
    Department of Computer Architecture. Universitat Politecnica de Catalunya. Barcelona, Spain .
    Moll, Agusti
    Fundacio Privada per la Xarxa Lliure, Oberta i Neural Guifi.net. Mas l’Esperanca, 08503 Gurb, Catalonia.
    Navarro, Leandro
    Department of Computer Architecture. Universitat Politecnica de Catalunya. Barcelona, Spain.
    Pueyo, Roger
    Fundacio Privada per la Xarxa Lliure, Oberta i Neural Guifi.net. Mas l’Esperanca, 08503 Gurb, Catalonia.
    Vlassov, Vladimir
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Cloud-based community services in community networks2016In: 2016 International Conference on Computing, Networking and Communications, ICNC 2016, IEEE conference proceedings, 2016, 1-5 p., 7440621Conference paper (Refereed)
    Abstract [en]

    Wireless networks have shown to be a cost effective solution for an IP-based communication infrastructure in under-served areas. Services and application, if deployed within these wireless networks, add value for the users. This paper shows how cloud infrastructures have been made operational in a community wireless network, as a particular case of a community cloud, developed according to the specific requirements and conditions of the community. We describe the conditions and requirements of such a community cloud and explain our technical choices and experience in its deployment in the community network. The user take-up has started, and our case supports the tendency of cloud computing moving towards the network edge.

  • 187.
    Baig, Roger
    et al.
    Fundacio Privada per la Xarxa Lliure, Oberta i Neural Guifi.net. Mas l’Esperanca, 08503 Gurb, Catalonia.
    Freitag, Felix
    Department of Computer Architecture. Universitat Politecnica de Catalunya. Barcelona, Spain .
    Moll, Agusti
    Fundacio Privada per la Xarxa Lliure, Oberta i Neural Guifi.net. Mas l’Esperanca, 08503 Gurb, Catalonia.
    Navarro, Leandro
    Department of Computer Architecture. Universitat Politecnica de Catalunya. Barcelona, Spain.
    Pueyo, Roger
    Fundacio Privada per la Xarxa Lliure, Oberta i Neural Guifi.net. Mas l’Esperanca, 08503 Gurb, Catalonia.
    Vlassov, Vladimir
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Community network clouds as a case for the IEEE Intercloud standardization2015In: 2015 IEEE Conference on Standards for Communications and Networking, CSCN 2015, 2015, 269-274 p., 7390456Conference paper (Refereed)
    Abstract [en]

    The IEEE P2302 Intercloud WG conducts work since 2011 on the project Standard for Intercloud Interoperability and Federation with the goal to define a standard architecture and building components for large-scale interoperability of independent cloud providers. While the standardization process has achieved fine-grained definitions of several Intercloud components, a deployment of the Intercloud to demonstrate the architectural feasibility is not yet operational. In this paper, we describe a deployed community network cloud and we show how it matches in several aspects the vision of the Intercloud. Similar to the Intercloud, the community network cloud consists of many small cloud providers, which for interoperability use a set of common services. In this sense, the community network cloud is a real use case for elements that the Intercloud standardization WG envisions, and can feed back to and even become part of the Intercloud. In fact, a study on Small or Medium Enterprise (SME) provided commercial services in the community network cloud indicates the importance of the success of the Intercloud standardization initiative for SMEs.

  • 188.
    Balador, Ali
    et al.
    Polytechnic University of Valencia, Valencia, Spain.
    Böhm, Annette
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Mälardalen University, Västerås, Sweden.
    Calafate, Carlos T.
    Polytechnic University of Valencia, Valencia, Spain.
    Ji, Yusheng
    National Institute of Informatics, Tokyo, Japan.
    Cano, Juan-Carlos
    Polytechnic University of Valencia, Valencia, Spain.
    Manzoni, Pietro
    Polytechnic University of Valencia, Valencia, Spain.
    An Efficient MAC Protocol for vehicle platooning in automated highway systems2015Conference paper (Refereed)
    Abstract [en]

    Lately, all the top truck manufacturers are investing considerable resources in the research and development of platooning systems which would allow vehicles to save fuel and improve safety by travelling in a close-following manner. The platooning system requires frequent and reliable vehicle-to-vehicle communications. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if re-transmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability considerably compared to pure 802.11p.

  • 189.
    Balasubramaniam, Sasitharan
    et al.
    Tampere University of Technology, Tampere, Finland .
    Lyamin, Nikita
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kleyko, Denis
    Luleå University of Technology, Luleå, Sweden.
    Skurnik, Mikael
    University of Helsinki, Helsinki, Finland .
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Koucheryavy, Yevgeni
    Tampere University of Technology, Tampere, Finland .
    Exploiting bacterial properties for multi-hop nanonetworks2014In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 52, no 7, 184-191 p.Article in journal (Refereed)
    Abstract [en]

    Molecular communication is a relatively new communication paradigm for nanomachines where the communication is realized by utilizing existing biological components found in nature. In recent years researchers have proposed using bacteria to realize molecular communication because the bacteria have the ability to swim and migrate between locations, carry DNA contents (i.e. plasmids) that could be utilized for information storage, and interact and transfer plasmids to other bacteria (one of these processes is known as bacterial conjugation). However, current proposals for bacterial nanonetworks have not considered the internal structures of the nanomachines that can facilitate the use of bacteria as an information carrier. This article presents the types and functionalities of nanomachines that can be utilized in bacterial nanonetworks. A particular focus is placed on the bacterial conjugation and its support for multihop communication between nanomachines. Simulations of the communication process have also been evaluated, to analyze the quantity of bits received as well as the delay performances. Wet lab experiments have also been conducted to validate the bacterial conjugation process. The article also discusses potential applications of bacterial nanonetworks for cancer monitoring and therapy. © 2014 IEEE.

  • 190. Baldini, Gianmarco
    et al.
    Kounelis, Ioannis
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. European Commiss, Joint Res Ctr, Inst Protect & Secur Citizen, Ispra, VA, Italy..
    Loeschner, Jan
    Tallacchini, Mariachiara
    European Citizens and Their Trust in Social Networks2014In: Learning and Collaboration Technologies. Technology-Rich Environments for Learning and Collaboration: First International Conference, LCT 2014, Held as Part of HCI International 2014, Heraklion, Crete, Greece, June 22-27, 2014, Proceedings, Part II, Springer International Publishing , 2014Conference paper (Refereed)
    Abstract [en]

    In information and communication technology (ICT) trust has been considered as a crucial component of digital interactions. Trust has been dissected in a variety of potential meanings and dimensions and through the merging of trust in humans and trust in machines. In this paper, we investigate the role and the aggregation of trust in social networks and blogs and how it relates to knowledge production, and its connections to concepts such as reputation and sustainability in the European context. Moreover, we discuss knowledge production in information and communication technology and its relationship to user trust. We develop a view on the co-production of knowledge and trust and propose a policy management framework to support the users in their trusted use of social networks and blogs. This is presented based on an e-health use case analysis considering web based reputation and developing a new reputation scheme.

  • 191. Baliosian, J.
    et al.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Decentralized configuration of neighboring cells for radio access networks2007In: 2007 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks, WOWMOM, IEEE , 2007, 4351740- p.Conference paper (Refereed)
    Abstract [en]

    In order to execute a handover processes in a Radio Access Network, each cell has a configured list of neighbors to which such handovers are made. Rapid re-configuration of the neigh-borhood list in response to network failures and other events is currently not possible. To address this problem, this paper suggests an autonomic approach for dynamically configuring neighboring cell lists and introduces a decentralized, three-layered framework. As a key element of this framework, a novel probabilistic protocol that detects and continuously tracks the coverage overlaps among cells is presented and evaluated. The protocol, called DOC, maintains a distributed graph of over-lapping cells. Due to using Bloom fillers and aggregation techniques, it exhibits a low traffic and computational overhead. A first series of simulation studies suggests that DOC is scalable with respect to network size and the number of terminals.

  • 192. Bang, I.
    et al.
    Kim, Su Min
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Sung, D. K.
    Opportunistic user selection with adaptive jamming for secure communication in heterogeneous networks2015In: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, IEEE conference proceedings, 2015, 42-46 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose an opportunistic user selection criterion to obtain a multiuser diversity gain for secure communication. At the same time, we also propose a strategy for utilizing a small base station in heterogeneous networks as a helper or a jammer adaptively. Our approach is to maximize the secrecy achievable rate based on an analytically derived lower bound instead of the original objective function due to its complexity. Based on a simple proposed user selection criterion considering both macro and small base stations, we propose two jamming strategies according to knowledge of eavesdropper's channel: adaptive jamming and probabilistic jamming strategies. Through simulations in two scenarios, it is shown that our proposed user selection and jamming schemes provide a good performance gain in terms of secrecy achievable rate.

  • 193.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    LPED: Channel Diagnostics in WSN Through Channel Coding and Symbol Error Statistics2014In: IEEE ISSNIP 2014 - 2014 IEEE 9th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, Conference Proceedings, Singapore: IEEE Sensors Council, 2014, 1-6 p.Conference paper (Refereed)
    Abstract [en]

    Three major obstacles to wireless communication are electromagnetic interference, multipath fading and signal attenuation. The former stems mainly from collocated wireless systems operating in the same frequency band, while the latter two originate from physical properties of the environment. Identifying the source of packet corruption and loss is crucial, since the adequate countermeasures for different types of threats are essentially different. This problem is especially pronounced in industrial monitoring and control applications, where IEEE 802.15.4 communication is expected to deliver data within tight deadlines, with minimal packet loss. This work presents the Lightweight Packet Error Discriminator (LPED) that distinguishes between errors caused by multipath fading and attenuation, and those inflicted by IEEE 802.11 interference. LPED uses Forward Error Correction to determine the symbol error positions inside erroneously received packets and calculates the error density, which is then fed to a discriminator for error source classification. The statistical constituents of LPED are obtained from an extensive measurement campaign in two different types of industrial environments. The classifier incurs no overhead and in ≥90% of cases a single packet is sufficient for a correct channel diagnosis. Experiments show that LPED accelerates link diagnostics by at least 190%, compared to the relevant state-of-the-art approaches.

  • 194.
    Barac, Filip
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. ABB Corp Res, S-72178 Vasteras, Sweden.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Scrutinizing Bit- and Symbol-Errors of IEEE 802.15.4 Communication in Industrial Environments2014In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 63, no 7, 1783-1794 p.Article in journal (Refereed)
    Abstract [en]

    The knowledge of error nature in wireless channels is an essential constituent of efficient communication protocol design. To this end, this paper is the first comprehensive bit- and symbol-level analysis of IEEE 802.15.4 transmission errors in industrial environments. The intention with this paper is to extract the error properties relevant for future improvements of wireless communication reliability and coexistence of radio systems in these harsh conditions. An extensive set of bit-error traces was collected in a variety of scenarios and industrial environments, showing that error behavior is highly dependent on the cause of packet corruption. It is shown that errors inflicted by multipath fading and attenuation exhibit different properties than those imposed by IEEE 802.11 interference. The statistical behavior of these two patterns is concurrently investigated in terms of differences in bit-error distribution, error burst length, channel memory length, and the scale of packet corruption. With these conclusions at hand, abiding to the computational constraints of embedded sensors and the statistical properties of bit-errors, a Reed-Solomon $(15,k)$ block code is chosen to investigate the implications of bit-error nature on practical aspects of channel coding and interleaving. This paper is concluded by a number of findings of high practical relevance, concerning the optimal type, depth, and meaningfulness of interleaving.

  • 195.
    Barac, Filip
    et al.
    Ericsson AB.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Zhang, Tingting
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Sisinni, Emiliano
    University of Brescia.
    Error Manifestation in Industrial WSN Communication and Guidelines for Countermeasures2017In: Wireless Sensor Systems for Extreme Environments: Space, Underwater, Underground and Industrial / [ed] H. F. Rashvand and A. Abedi, John Wiley & Sons, 2017Chapter in book (Refereed)
  • 196.
    Barac, Filip
    et al.
    Mid Sweden University.
    Yu, Kan
    Mälardalen University, School of Innovation, Design and Engineering.
    Gidlund, Mikael
    ABB, Corporate Research.
    Åkerberg, Johan
    ABB, Corporate Research.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Towards Reliable and Lightweight Communication in Industrial Wireless Sensor Networks2012Conference paper (Refereed)
    Abstract [en]

    In this paper we address the issues of timeliness and transmission reliability of existing industrial communication standards. We combine a Forward Error Correction coding schemeon the Medium Access Control layer with a lightweight routing protocol to form an IEEE 802.15.4-conformable solution, whichcan be implemented into already existing hardware without violating the standard. After laying the theoretical foundations,we conduct a performance evaluation of the proposed solution.The results show a substantial gain in reliability and reducedlatency, compared to the uncoded transmissions, as well ascommon Wireless Sensor Network routing protocols.

  • 197. Barkowsky, M
    et al.
    Brunnström, Kjell
    Acreo ICT Swedish AB.
    Ebrahimi, T
    Karam, L
    Lebreton, P
    Le Callet, P
    Perkis, A
    Raake, A
    Subedar, M
    Wang, Kun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Xing, L
    You, J
    Subjective and Objective Visual Quality Assessment in the Context of stereoscopic 3DTV2013In: 3DTV System with Depth-Image-Based Rendering / [ed] Yu, L., Tanimoto, M., and Zhu, C., Springer, 2013, 413-437 p.Chapter in book (Refereed)
    Abstract [en]

    Subjective and objective visual quality assessment in the context of stereoscopic three-dimensional TV (3D-TV) is still in the nascent stage and needs to consider the effect of the added depth dimension. As a matter of fact, quality assessment of 3D-TV cannot be considered as a trivial extension of two-dimensional (2D) cases. Furthermore, it may also introduce negative effects not experienced in 2D, e.g., discomfort or nausea. Based on efforts initiated within the cost action ICT 1003 QUALINET, this chapter discusses current challenges in relation to subjective and objective visual quality assessment for stereo-based 3D-TV. Two case studies are presented to illustrate the current state of the art and some of the remaining challenges. © Springer Science+Business Media New York 2013. All rights are reserved.

  • 198.
    Barkowsky, M
    et al.
    University of Nantes, France.
    Masala, E
    Politecnico di Torino, Italy.
    Van Wallendael, G
    Ghent University - iMinds, Belgium.
    Brunnström, Kjell
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems. Acreo Swedish ICT AB, Sweden .
    Staelens, N
    Ghent University - iMinds, Belgium.
    Le Callet, P
    University of Nantes, France.
    Objective Video Quality Assessment - Towards large scale video database enhanced model development.2015In: IEICE transactions on communications, ISSN 0916-8516, E-ISSN 1745-1345, Vol. E98-B, no 1, 2-11 p.Article in journal (Refereed)
    Abstract [en]

    The current development of video quality assessment algorithms suffers from the lack of available video sequences for training, verification and validation to determine and enhance the algorithm's application scope. The Joint Effort Group of the Video Quality Experts Group (VQEG-JEG) is currently driving efforts towards the creation of large scale, reproducible, and easy to use databases. These databases will contain bitstreams of recent video encoders (H.264, H.265), packet loss impairment patterns and impaired bitstreams, pre-parsed bitstream information into files in XML syntax, and well-known objective video quality measurement outputs. The database is continuously updated and enlarged using reproducible processing chains. Currently, more than 70,000 sequences are available for statistical analysis of video quality measurement algorithms. New research questions are posed as the database is designed to verify and validate models on a very large scale, testing and validating various scopes of applications, while subjective assessment has to be limited to a comparably small subset of the database. Special focus is given on the principles guiding the database development, and some results are given to illustrate the practical usefulness of such a database with respect to the detailed new research questions.

  • 199. Baroffio, L.
    et al.
    Canclini, A.
    Cesana, M.
    Redondi, A.
    Tagliasacchi, M.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Eriksson, Emil
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Fodor, Viktoria
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Ascenso, J.
    Monteiro, P.
    Demo: Enabling image analysis tasks in visual sensor networks2014In: Proceedings of the 8th ACM/IEEE International Conference on Distributed Smart Cameras, ICDSC 2014, Association for Computing Machinery (ACM), 2014, a46- p.Conference paper (Refereed)
    Abstract [en]

    This demo showcases some of the results obtained by the GreenEyes project, whose main objective is to enable visual analysis on resource-constrained multimedia sensor networks. The demo features a multi-hop visual sensor network operated by BeagleBones Linux computers with IEEE 802.15.4 communication capabilities, and capable of recognizing and tracking objects according to two different visual paradigms. In the traditional compress-then-analyze (CTA) paradigm, JPEG compressed images are transmitted through the network from a camera node to a central controller, where the analysis takes place. In the alternative analyze-then-compress (ATC) paradigm, the camera node extracts and compresses local binary visual features from the acquired images (either locally or in a distributed fashion) and transmits them to the central controller, where they are used to perform object recognition/tracking. We show that, in a bandwidth constrained scenario, the latter paradigm allows to reach better results in terms of application frame rates, still ensuring excellent analysis performance.

  • 200.
    Bassoo, Vandana
    et al.
    Victoria University, Australia.
    Tom, K
    Victoria University, Australia.
    Mustafa, A. K.
    Victoria University, Australia.
    Cijvat, Ellie
    Lunds Universitet.
    Sjöland, Henrik
    Lunds Universitet.
    Faulkner, Mike
    Victoria University, Australia.
    Potential Architecture for Future Generation "Green" Wireless Base Station2009In: 2009 4th International Symposium on Wireless and Pervasive Computing, ISWPC 2009, IEEE, 2009, 4800602Conference paper (Refereed)
    Abstract [en]

    Current radio frequency power amplifiers (PAs) in 3G base stations have very high power consumption leading to a hefty cost and negative environmental impact. In this paper, we propose a potential architecture design for future wireless base station. Issues associated with components of the architecture are investigated. A comparison of PA with pulse width modulation drive and PA with envelope elimination and restoration (EER) drive is offered. EER-driven PA promises high efficiency over a wide dynamic range but has bandwidth expansion problems. A novel approach which reduces bandwidth expansion on the envelope by 54% is proposed. A modulator is used to convert amplitude and phase information into the edges of a pulse train. The modulator also eradicates some analog components present in traditional base station design.

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