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  • 1. Abedifar, V.
    et al.
    Furdek, Marija
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Muhammad, Ajmal
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Eshghi, M.
    Wosinska, Lena
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Routing, modulation format, spectrum and core allocation in SDM networks based on programmable filterless nodes2018In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    An RMSCA approach based on binary particle swarm optimization is proposed for programmable filterless SDM networks, aimed at minimizing core and spectrum usage. Nearoptimal resource consumption.

  • 2. Antichi, Gianni
    et al.
    Castro, Ignacio
    Chiesa, Marco
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab). Université catholique de Louvain.
    Fernandes, Eder L.
    Lapeyrade, Remy
    Kopp, Daniel
    Han, Jong Hun
    Bruyere, Marc
    Dietzel, Christoph
    Gusat, Mitchell
    Moore, Andrew W.
    Owezarski, Philippe
    Uhlig, Steve
    Canini, Marco
    ENDEAVOUR: A Scalable SDN Architecture For Real-World IXPs2017In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 11, p. 2553-2562Article in journal (Refereed)
    Abstract [en]

    Innovation in interdomain routing has remained stagnant for over a decade. Recently, Internet eXchange Points (IXPs) have emerged as economically-advantageous interconnection points for reducing path latencies and exchanging ever increasing traffic volumes among, possibly, hundreds of networks. Given their far-reaching implications on interdomain routing, IXPs are the ideal place to foster network innovation and extend the benefits of software defined networking (SDN) to the interdomain level. In this paper, we present, evaluate, and demonstrate ENDEAVOUR, an SDN platform for IXPs. ENDEAVOUR can be deployed on a multi-hop IXP fabric, supports a large number of use cases, and is highly scalable, while avoiding broadcast storms. Our evaluation with real data from one of the largest IXPs, demonstrates the benefits and scalability of our solution: ENDEAVOUR requires around 70% fewer rules than alternative SDN solutions thanks to our rule partitioning mechanism. In addition, by providing an open source solution, we invite everyone from the community to experiment (and improve) our implementation as well as adapt it to new use cases.

  • 3.
    Apanasevic, Tatjana
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Opportunities and challenges of mobile payment services: The perspective of service providers2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

     Mobile payments are transforming the payments industry. These services open up the opportunity for non-banking actors to enter the market. In order to embrace this challenge, banks, traditional payments market players, are forced to launch mobile payments. However, in Europe and most developed economies, a big number of launched services get terminated soon after their introduction in the market. Hence, the ability of different actors to act locally calls for additional research.

    The main objective of this thesis is to broaden knowledge and understanding about the ways mobile payment service providers address the opportunities and challenges of mobile payment services. In order to investigate this problem, this research (i) explores factors stimulating and hindering the introduction of mobile payments using perspectives of different types of service providers (i.e., banks, independent providers, direct operator billing providers, retailers, and public transport companies) and (ii) seeks to explain the importance of these factors for each type of provider.

    The primary data collected using interview method. More than 40 industry representatives in six countries were contacted. The Service, Technology, Organisation, and Finance (STOF) model was used as a theoretical research framework. This is a business modelling framework that specifies a set of critical design issues that have to  be considered within each model’s domain.

    Research findings highlight that the organisation domain is the key domain, which  affects all other domains and has an impact on the general viability of the business model. A comparison of the approaches used by different service providers to address each of the critical design issues helped to identify the factors that are most important within each domain. These factors stimulate or hinder development of a viable business model within each category of service providers.

    This research contributes to a better understanding of challenges and success factors associated with the design of business models for new mobile services and uses the lens of the STOF model. The contributions to the academic research on mobile payments are: (i) collection and analysis of a rich empirical data set on mobile payment services implemented in six Northern European countries, (ii) discussion of a bigger picture by connecting research findings to the context of the existing payment system, (iii) extension  of knowledge on business models for mobile ticketing, and (iv) extension of knowledge on the value of mobile ticketing services in the business-to-business (B2B) context.

  • 4.
    Apanasevic, Tatjana
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Primary data collection: Approaches of service providers towards mobile payments2018Report (Other academic)
    Abstract [en]

    Mobile payments are new services enabled by evolution of information and communication technologies. These services can be provided by different types of actors both banks and non-banks. The understanding of capabilities and limitations of different service providers to act in local markets requires further understanding. Implemented research seeks to extend knowledge in this area. I have implemented research focused on approaches used by different types of service providers including banks, independent providers, operator billing providers, retailers, and public transport companies in six Northern European countries.

    Exploratory part of the research aims to address the following research question: What factors stimulate and hinder the introduction of mobile payments? The main objective of this report is to present primary data collected during the research through interviews with contacted companies.

    The collected primary data is classified and organised using the STOF (Service, Technology, Organisation, and Finance) model. Evidence is presented in tables. This primary data is further used for explanatory study. At the same time, this data can be used by other researchers studying the same area. The collected data is reach in facts and presents the overview of different strategies. 

  • 5.
    Apanasevic, Tatjana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Arvidsson, Niklas
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability and Industrial Dynamics.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Mobile payments: a proposal for a context-oriented approach based on socio-technical system theoryIn: Journal of Innovation Management, ISSN 2183-0606Article in journal (Refereed)
    Abstract [en]

    A recent review on mobile payment research by Dahlberg et al. (2015) concludes that there is a need to synthesise this research area by studying contexts in which innovation is done as well as to integrate different aspects of research. This article aims to provide a proposal for how to achieve such integration and context-orientation by building on previous studies as well as an additional review. Our systematic literature review of mobile payments research is focused on papers published during 2006–2016. The main objective is to examine how mobile payments research has been conducted from the methodological and theoretical perspectives. Our findings show that research on mobile payments is a multidisciplinary research. Three main themes, which are in line with previous studies, in research are: customer adoption, technological aspects, and business aspects. Moreover, research is mainly analytical based on deductive approach. To meet the challenge formulated in the previous research, we propose and apply a socio-technical system framework to achieve synthesis and context-specific consideration in future research on mobile payments.

  • 6.
    Apanasevic, Tatjana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Mobile ticketing services in the Northern Europe: Critical business model issues2018In: Internet of Things Business Models, Users, and Networks, 2017 / [ed] Morten Falch, Copenhagen, Denmark: IEEE, 2018, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Started as SMS ticketing, today, mobile ticketing services become a platform for combined mobility solutions that integrate mobile ticketing, bike renting, car sharing, and parking payment services. Mobile ticketing services provide a number of benefits for public transport companies and passengers, however, in some Northern European countries, the share of mobile ticket sales does not exceed 10 percent. In this paper, we analyse business models of three types of mobile ticketing services (SMS, in-app, and “Be-In Be-Out” (BIBO)) in order to identify factors that negatively affect wider penetration of mobile ticketing. In order to do so, we use STOF (Service, Technology, Organisation, and Finance) model. The research reveals that there are a number of challenges related to service, technology, and finance domains of mobile ticketing. Due to this, with the help of price policy, many public transport companies push choices of their customers towards use of plastic travel card.

  • 7.
    Apanasevic, Tatjana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Mobile ticketing services in the Northern Europe Critical business model issues2017In: 2017 JOINT 13TH CTTE AND 10TH CMI CONFERENCE ON INTERNET OF THINGS - BUSINESS MODELS, USERS, AND NETWORKS / [ed] Falch, M, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Started as SMS ticketing, today, mobile ticketing services become a platform for combined mobility solutions that integrate mobile ticketing, bike renting, car sharing, and parking payment services. Mobile ticketing services provide a number of benefits for public transport companies and passengers, however, in some Northern European countries, the share of mobile ticket sales does not exceed 10 percent. In this paper, we analyse business models of three types of mobile ticketing services (SMS, in-app, and "Be-InBe-Out" (BIBO)) in order to identify factors that negatively affect wider penetration of mobile ticketing. In order to do so, we use STOF (Service, Technology, Organisation, and Finance) model. The research reveals that there are a number of challenges related to service, technology, and finance domains of mobile ticketing. Due to this, with the help of price policy, many public transport companies push choices of their customers towards use of plastic travel card.

  • 8.
    Apanasevic, Tatjana
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    The value of mobile ticketing from a public transport perspective2018In: Journal of Payments Strategy & Systems, Vol. 11, no 4, p. 292-305Article in journal (Refereed)
    Abstract [en]

    Within the field of mobile payments, the market segment for mobile ticketing services is expected to grow, driven by the public transport sector. Although a large number of studies have explored the value of mobile payments to customers (ie service end users), there is a lack of research exploring the value of mobile payment and mobile ticketing for business customers (ie transport companies and retailers). This paper aims to address this gap and to explore the kinds of value that mobile ticketing services create for public transport companies. The research considers mobile ticketing services in six Northern European countries. The research findings suggest that within the business-to-business context, mobile ticketing services create multiple dimensions of value, namely enhanced technical functionality; financial value; better working environment; operational value; and reputational and customer relationship value. For passengers, meanwhile, value takes the form of convenience and service enhancement. These benefits are factors driving adoption of mobile ticketing and mobile payment services by public transport companies.

  • 9.
    Azari, Amin
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Bitcoin Price Prediction: An ARIMA ApproachManuscript (preprint) (Other academic)
    Abstract [en]

    Bitcoin is considered as the most valuable currency in the world. Besides being highly valuable, its value has also experienced a steep increase, from around 1 dollar in 2010 to around 18000 in 2017. Then, in recent years, it has attracted considerable attention in a diverse set of fields, including economics and computer science. The former mainly focuses on studying how it affects the market, determining reasons behinds its price fluctuations, and predicting its future prices. The latter mainly focuses on its vulnerabilities, scalability, and other techno-cryptoeconomic issues. Here, we aim at revealing the usefulness of traditional autoregressive integrative moving average (ARIMA)model in predicting the future value of bitcoin by analyzing the price time series in a 3-years-long time period. On the one hand, our empirical studies reveal that this simple scheme is efficient in sub-periods in which the behavior of the time-series is almost unchanged, especially when it is used for short-term prediction,e.g. 1-day. On the other hand, when we try to train the Arima model to a 3-years-long period, during which the bitcoin price has experienced different behaviors, or when we try to use it for a long-term prediction, we observe that it introduces large prediction errors. Especially, the ARIMA model is unable to capture the sharp fluctuations in the price, e.g. the volatility at the end of 2017. Then, it calls for more features to be extracted and used along with the price for a more accurate prediction of the price. We have further investigated the bitcoin price prediction using an ARIMA model trained over the whole dataset, as well as a limited part of the history of the bitcoin price, with length of w, as inputs. Our study sheds lights on the interaction of the prediction accuracy, choice of (p; q; d), and window size w.

  • 10.
    Azari, Amin
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    On the DoF and Secure DoF of K-User MIMO Interference Channel with Instantaneous Relays2019Manuscript (preprint) (Other academic)
    Abstract [en]

    Interference channel, in which multiple user pairs communicate over shared resources, is a building block of communications networks. Here, the K-user interference channel (IC) aided by J instantaneous relays (IRs), i.e. relays without delay, is considered. For KICJR networks, where K>2 and J>1, the DoF performance and achievable schemes have not been investigated in literature. Here, we devise a novel achievable scheme, called restricted interference alignment (RIA), which restricts the received interference from each source at each destination in a limited sub-space, and then, aligns the restricted interferences. Furthermore, we develop an analytical tool for finding a tight upper bound on DoF of KICJR networks by analyzing the properness of the interference alignment equations. Moreover, we develop linear beamforming design for sources and relays based on the mean square error (MSE) minimization, as an achievable scheme. The performance evaluation results show that the achievable sum DoF by using the proposed RIA scheme and the MSE-based beamforming design match well with the derived upper bounds. Furthermore, the results confirm that the achieved sum DoF using the RIA scheme outperforms the existing achievable schemes. Motivated by these promising results, we further investigate impact of IRs in providing physical layer security, i.e. achieving secure DoF in interference networks. Specifically, we derive a lower bound on the achievable secure DoF by devising an achievable scheme, called transmission in the null space (TNS). This scheme makes the cross channels rank deficient and enables sources to select their transmit filters in the constructed null spaces. Performance evaluation shows that by leveraging IRs, the secure DoF performance of interference networks could be increased significantly. The proposed analytical framework in this work for rank deficiency-powered DoF analysis is expected to also attract attention from other research areas, e.g. beamforming design for millimeter wave communications.

    The full text will be freely available from 2019-02-01 12:35
  • 11.
    Azari, Amin
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Serving IoT Communications over Cellular Networks: Challenges and Solutions in Radio Resource Management for Massive and Critical IoT Communications2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Internet of Things (IoT) communications refer to the interconnections of smart devices, with reduced human intervention, which enable them to participate more actively in everyday life. It is expected that introduction of a scalable, energy efficient, and reliable IoT connectivity solution can bring enormous benefits to the society, especially in healthcare, wellbeing, and smart homes and industries. In the last two decades, there have been efforts in academia and industry to enable IoT connectivity over the legacy communications infrastructure. In recent years, it is becoming more and more clear that the characteristics and requirements of the IoT traffic are way different from the legacy traffic originating from existing communications services like voice and web surfing, and hence, IoT-specific communications systems and protocols have received profound attention. Until now, several revolutionary solutions, including cellular narrowband-IoT, SigFox, and LoRaWAN, have been proposed/implemented. As each of these solutions focuses on a subset of performance indicators at the cost of sacrificing the others, there is still lack of a dominant player in the market capable of delivering scalable, energy efficient, and reliable IoT connectivity. The present work is devoted to characterizing state-of-the-art technologies for enabling large-scale IoT connectivity, their limitations, and our contributions in performance assessment and enhancement for them. Especially, we focus on grant-free radio access and investigate its applications in supporting massive and critical IoT communications. The main contributions presented in this work include (a) developing an analytical framework for energy/latency/reliability assessment of IoT communications over grant-based and grant-free systems; (b) developing advanced RRM techniques for energy and spectrum efficient serving of massive and critical IoT communications, respectively; and (c) developing advanced data transmission/reception protocols for grant-free IoT networks. The performance evaluation results indicate that supporting IoT devices with stringent energy/delay constraints over limited radio resources calls for aggressive technologies breaking the barrier of the legacy interference-free orthogonal communications.

  • 12.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Bria, Aurelian
    System and method for providing communication rules based on a status associated with a battery of a device2017Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The disclosure relates to communication systems and, more particularly, to a system and method for providing communication rules based on a status associated with a battery of a device.

  • 13.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Performance Evaluation and Optimization of LPWA IoT Networks: A Stochastic Geometry Approach2018Conference paper (Refereed)
    Abstract [en]

    Leveraging grant-free radio access for enabling lowpowerwide-area (LPWA) Internet of Things (IoT) connectivityhas attracted lots of attention in recent years. Regarding lack ofresearch on LPWA IoT networks, this work is devoted to reliabilitymodeling, battery-lifetime analysis, and operation-controlof such networks. We derive the interplay amongst density ofthe access points, communication bandwidth, volume of trafficfrom heterogeneous sources, and quality of service (QoS) incommunications. The presented analytical framework comprisesmodeling of interference from heterogeneous sources with correlateddeployment locations and time-frequency asynchronousradio-resource usage patterns. The derived expressions representthe operation regions and rates in which, energy and costresources of devices and the access network, respectively, couldbe traded to achieve a given level of QoS in communications. Forexample, our expressions indicate the expected increase in QoSby increasing number of transmitted replicas, transmit power,density of the access points, and communication bandwidth.Our results further shed light on scalability of such networksand figure out the bounds up to which, scaling resources cancompensate the increase in traffic volume and QoS demand.Finally, we present an energy-optimized operation control policyfor IoT devices. The simulation results confirm tightness of thederived analytical expressions, and indicate usefulness of themin planning and operation control of IoT networks.

  • 14.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Self-organized Low-power IoT Networks: A Distributed Learning Approach2018Conference paper (Refereed)
    Abstract [en]

    Enabling large-scale energy-efficient Internet-ofthings(IoT) connectivity is an essential step towards realizationof networked society. While legacy wide-area wireless systemsare highly dependent on network-side coordination, the level ofconsumed energy in signaling, as well as the expected increase inthe number of IoT devices, makes such centralized approachesinfeasible in future. Here, we address this problem by selfcoordinationfor IoT networks through learning from pastcommunications. To this end, we first study low-complexity distributedlearning approaches applicable in IoT communications.Then, we present a learning solution to adapt communicationparameters of devices to the environment for maximizing energyefficiency and reliability in data transmissions. Furthermore,leveraging tools from stochastic geometry, we evaluate theperformance of proposed distributed learning solution againstthe centralized coordination. Finally, we analyze the interplayamongst energy efficiency, reliability of communications againstnoise and interference over data channel, and reliability againstadversarial interference over data and feedback channels. Thesimulation results indicate that compared to the state of the artapproaches, both energy efficiency and reliability in IoT communicationscould be significantly improved using the proposedlearning approach. These promising results, which are achievedusing lightweight learning, make our solution favorable in manylow-cost low-power IoT applications.

  • 15.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Ozger, Mustafa
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Serving Non-Scheduled URLLC Traffic: Challenges and Learning-Powered StrategiesManuscript (preprint) (Other academic)
    Abstract [en]

    Supporting ultra-reliable low-latency communications (URLLC) is a major challenge of 5G wireless networks. Whilst enabling URLLC is essential for realizing many promising 5G applications, the design of communications' solutions for serving such unseen type of traffic with stringent delay and reliability requirements is in its infancy. In prior studies, physical and MAC layer solutions for assuring the end-to-end delay requirement of scheduled URLLC traffic have been investigated. However, there is lack of study on enabling non-scheduled transmission of urgent URLLC traffic, especially in coexistence with the scheduled URLLC traffic. This study at first sheds light into the coexistence design challenges, especially the radio resource management (RRM) problem. It also leverages recent advances in machine learning (ML) to exploit spatial/temporal correlation in user behaviors and use of radio  resources, and proposes a distributed risk-aware ML solution for RRM. The proposed solution benefits from hybrid orthogonal/non-orthogonal radio resource slicing, and proactively regulates the spectrum needed for satisfying delay/reliability requirement of each traffic type. A case study is introduced to investigate the potential of the proposed RRM in serving coexisting URLLC traffic types. The results further provide insights on the interplay between the reliabilities of coexisting traffic, uncertainties in users' demands and channel conditions, and amount of required radio resources.

  • 16.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Masoudi, Meysam
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Optimized Resource Provisioning and Operation Control for Low-power Wide-area IoT NetworksManuscript (preprint) (Other academic)
    Abstract [en]

    Grant-free radio access is a promising solution for reducing energy consumption and access delay in low power wide-area (LPWA) Internet of Things (IoT) networks. This work is devoted to reliability modeling, battery-lifetime analysis, resource provisioning, and operation control for grantfreeIoT networks. Our modeling captures correlation in devices’locations, benefits from 3D (time/frequency/code) interference analysis, and enables coexistence analysis of multi-type IoT technologies. We derive the interplay amongst density of the access points, communication bandwidth, traffic volume, and quality of service (QoS) of communications. Deriving the interplay enables scalability analysis, i.e. it figures out the required increase in device's energy consumption (or access network’s resources) for compensating the increase in traffic volume or QoS demand. Our major contribution consists in deriving traffic loads and respective exchange rates in which, energy and cost resources of devices and the access network, respectively, could be traded to achieve a given level of QoS. We further indicate operation regions in which scaling a parameter turns from being a friend into a foe. Finally, we present energy- and cost-optimized operation control and resource provisioning strategies, respectively. The simulation results confirm tightness of the analytical expressions, and indicate the usefulness of them in planning and operation control of IoT networks.

  • 17.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Stefanovic, Cedomir
    Aalborg University.
    Popovski, Petar
    Aalborg University.
    Latency-Energy Tradeoff based on Channel Scheduling and Repetitions in NB-IoT Systems2018Conference paper (Refereed)
    Abstract [en]

    Narrowband IoT (NB-IoT) is the latest IoT connectivitysolution presented by the 3GPP. NB-IoT introduces coverageclasses and introduces a significant link budget improvementby allowing repeated transmissions by nodes that experiencehigh path loss. However, those repetitions necessarily increase theenergy consumption and the latency in the whole NB-IoT system.The extent to which the whole system is affected depends on thescheduling of the uplink and downlink channels. We addressthis question, not treated previously, by developing a tractablemodel of NB-IoT access protocol operation, comprising messageexchanges in random-access, control, and data channels, bothin the uplink and downlink. The model is then used to analyzethe impact of channel scheduling as well as the interaction ofcoexisting coverage classes, through derivation of the expectedlatency and battery lifetime for each coverage class. These resultsare subsequently employed in investigation of latency-energytradeoff in NB-IoT channel scheduling as well as determiningthe optimized operation points. Simulations results show validityof the analysis and confirm that there is a significant impact ofchannel scheduling on latency and lifetime performance of NBIoTdevices.

  • 18.
    Azari, Amin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Popovski, Petar
    Stefanovic, Cedomir
    Cavdar, Cicek
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Grant-Free Radio Access for Cellular IoTManuscript (preprint) (Other academic)
    Abstract [en]

    Radio resource management (RRM) is a major factor affecting the delay, reliability, and energy consumption of Internet of Things (IoT) communications. This article is focused on grant-free access, a class of techniques suited to support massive IoT connectivity. Within the proposed scheme, the IoT devices transmit multiple replicas of the same packet. In addition to that, the receiver makes use of the random timing and frequency offsets in order to carry out Successive Interference Cancellation (SIC). The system performance is investigated by using a model based on stochastic geometry, leading to closed-form expressions for the key performance indicators, such as reliability and battery lifetime. The framework allows optimization of the number of replicas per device. This results in overall improvement of the energy consumption, delay and reliability, at the expense of more complex processing at the Base Station. The evaluation results indicate that the proposed data transmission and reception schemes can significantly prolong battery lifetime of IoT devices by removing the need for connection establishment and reducing the number of retransmissions. The obtained results also indicate existence of traffic-load regions, where grant-free radio access outperforms the grant-based one, which is used in LTE and NB-IoT systems. These results pave the way for enabling intelligent grant-based/free operation mode switching in 5G networks.

  • 19.
    Bai, Chumeng
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Evaluation and Improvement of Decentralized Congestion Control for Multiplatooning Application2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Platooning has the potential to be a breakthrough in increasing road capacity and reducing fuel consumption, as it allows a chain of vehicles to closely follow each other on the road. When the number of vehicles increases, platoons will follow one another in what is referred to as multiplatooning. Many Cooperative Intelligent Transportation Systems (C-ITS) applications rely on periodically exchanged beacons among vehicles to improve traffic safety. However, as the number of connected vehicles increases, the network may become congested due to periodically exchanged beacons. Therefore, without some congestion control method, safety critical messages such as Cooperative Awareness Messages (CAMs) may not be delivered on time in high vehicle density scenarios. Both the European Telecommunications Standards Institute (ETSI) and the Institute of Electrical and Electronics Engineers (IEEE) have been working on different standards to support vehicular communication. ETSI dened the Decentralized Congestion Control (DCC) mechanism which adapts transmission parameters (message rate, transmit data rate, and transmit power, etc.) to keep channel load under control. ETSI DCC utilizes a three-state machine with RELAXED, ACTIVE, and RESTRICTIVE states. In this thesis, we implemented this three-state machine by adapting the message rate based on the channel busy ratio (CBR). We name this message-rate based three-state machine DCC-3. DCC-3 has the ability to control channel load; however, it has unfairness and instability problems due to the dramatic parameter changes between states. Therefore, we divided the ACTIVE state of DCC-3 into ve sub-states, and refer to this as DCC-7. We benchmarked DCC-3 against static beaconing (STB), dynamic beaconing (DynB), LInear MEssage Rate Integrated Control (LIMERIC), and DCC-7 using different evaluation metrics with different numbers of platoons. Our results from the Plexe simulator demonstrate that DCC-7 has the best performance when considering all evaluation metrics, including CBR, Inter-reception time (IRT), collisions, safe time ratio, and fairness. Furthermore, we found using transmit power control could greatly improve the performance of CBR and collision rates.

  • 20.
    Besharat Pour, Shiva
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Li, Qi
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Connecting Silos: Automation system for thesis processing in Canvas and DiVA2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As the era of digitalization dawns, the need to integrate separate silos into a synchronized connected system is becoming of ever greater significance. This thesis focuses on the Canvas Learning Management System (LMS) and the Digitala vetenskapliga arkive (DiVA) as examples of separate silos.

    The thesis presents several methods of automating document handling associated with a degree project. It exploits the fact that students will submit their thesis to their examiner via Canvas. Canvas is the LMS platform used by students to submit all their coursework. When the examiner approves the thesis, it will be archived in DiVA and optionally published on DiVA. DiVA is an institutional repository used for research publications and student theses.

    When manually archiving and publishing student theses on DiVA several fields need to be filled in. These fields provide meta data for the thesis itself. The content of these fields (author, title, keywords, abstract, …) can be used when searching via the DiVA portal. It might not seem like a massive task to enter this meta data for an individual thesis; however, given the number of theses that are submitted every year, this process takes a large amount of time and effort. Moreover, it is important to enter this data correctly, which is difficult when manually doing this task. Therefore, this thesis project seeks to automate this process for future theses.

    The proposed solution parses PDF documents and uses information from the LMS in order to automatically generate a cover for the thesis and fill in the required DiVA meta data. Additionally, information for inserting an announcement of the student's oral thesis presentation into a calendar system will be provided. Moreover, the data in each case will be checked for correctness and consistency.

    Manually filling in DiVA fields in order to publish theses has been a quite demanding and time-consuming process. Thus, there is often a delay before a thesis is published on DiVA. Therefore, this thesis project’s goal is to provide KTH with an automated means to handle thesis archiving and publication on DiVA, while doing so more efficiently, and with fewer errors. The correctness of the extracted meta data will be evaluated by comparing the results to the previously entered meta data for theses that have previously been achieved in DiVA. The automated process has been calculated to take roughly 50 seconds to prepare the information needed to publish a thesis to DiVA with ~71% accuracy, compared with 1 hour and 34% accuracy in the previous manual method.

  • 21.
    Bogdanov, Kirill
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Enabling Fast and Accurate Run-Time Decisions in Geo-Distributed Systems: Better Achieving Service Level Objectives2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Computing services are highly integrated into modern society and used  by millions of people daily. To meet these high demands, many popular  services are implemented and deployed as geo-distributed applications on  top of third-party virtualized cloud providers. However, the nature of  such a deployment leads to variable performance. To deliver high quality  of service, these systems strive to adapt to ever-changing conditions by  monitoring changes in state and making informed run-time decisions, such  as choosing server peering, replica placement, and redirection of requests. In  this dissertation, we seek to improve the quality of run-time decisions made  by geo-distributed systems. We attempt to achieve this through: (1) a better  understanding of the underlying deployment conditions, (2) systematic and  thorough testing of the decision logic implemented in these systems, and (3)  by providing a clear view of the network and system states allowing services  to make better-informed decisions.  First, we validate an application’s decision logic used in popular  storage systems by examining replica selection algorithms. We do this by  introducing GeoPerf, a tool that uses symbolic execution and modeling to  perform systematic testing of replica selection algorithms. GeoPerf was used  to test two popular storage systems and found one bug in each.  Then, using measurements across EC2, we observed persistent correlation  between network paths and network latency. Based on these observations,  we introduce EdgeVar, a tool that decouples routing and congestion based  changes in network latency. This additional information improves estimation  of latency, as well as increases the stability of network path selection.  Next, we introduce Tectonic, a tool that tracks an application’s requests  and responses both at the user and kernel levels. In combination with  EdgeVar, it decouples end-to-end request completion time into three  components of network routing, network congestion, and service time.  Finally, we demonstrate how this decoupling of request completion  time components can be leveraged in practice by developing Kurma, a  fast and accurate load balancer for geo-distributed storage systems. At  runtime, Kurma integrates network latency and service time distributions to  accurately estimate the rate of Service Level Objective (SLO) violations, for  requests redirected between geo-distributed datacenters. Using real-world  data, we demonstrate Kurma’s ability to effectively share load among  datacenters while reducing SLO violations by a factor of up to 3 in high  load settings or reducing the cost of running the service by up to 17%. The  techniques described in this dissertation are important for current and future  geo-distributed services that strive to provide the best quality of service to  customers while minimizing the cost of operating the service.  

  • 22.
    Chang, Peiliang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Cross-Layer Energy-Efficient Mobile Network Design2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To assure the sustainable development of mobile networks, it is crucial to improve their energy efficiency. This thesis is devoted to the design of energy-efficient mobile networks. A cross-layer design approach is adopted. The resource management at the MAC layer, the network layer as well as the service layer are optimized to improve the energy efficiency of mobile networks. The problem of optimizing the MAC-layer resource allocation of the downlink transmission in multi-carrier NOMA systems to maximize the system energy efficiency while satisfying users’ QoS requirements is firstly considered. The optimal power allocation across sub-carriers and across users sharing one sub-carrier are proposed. Furthermore, exploiting the structure of the optimal power allocation across users sharing one sub-carrier, a sub-optimal solution for sub-carrier assignment, which greedily minimizes the required power to serve all users with required QoS, is developed. Besides optimizing the channel assignment and power allocation within a single cell, the link scheduling in the multi-cell scenario to deal with inter-cell interference is also studied. A scalable distributed link scheduling solution is proposed to orchestrate the transmission and DTX micro-sleep of multiple base stations such that both the inter-cell interference and the energy consumption are reduced. At the network layer, the operation of base station sleeping is optimized to improve the energy efficiency of mobile networks without deteriorating users’ QoS. The spectral and energy efficiency of mobile networks, where base stations are enabled with DTX, under different traffic load is firstly studied. It shows that as the networks are more loaded, the link spectral efficiency reduces while the network spectral efficiency increases. Regarding the network energy efficiency, it will either firstly increase and then decrease or always increase when the network load gets higher. The optimal network load to maximize the network energy efficiency depends on the power consumption of base stations in DTX sleep mode. Based on the findings of the above study, the joint optimization of cell DTX and deep sleep to maximize the network energy efficiency is investigated. A scaling law of transmit power, which assures that the distribution of the received power remains unchanged as more base stations are switched into deep sleep, is proposed. Then the average resource utilization and overload probability of non-deep-sleep base stations are derived. Based on these results, the feasible range of the percentage of deep-sleep base stations is obtained. Finally, the optimal percentage of deep-sleep base stations to maximize the network energy efficiency while satisfying users’ QoS requirements is derived. Lastly, the service-layer resource provision of edge computing in mobile networks is optimized to improve the energy efficiency. With this work, the trade-offs on service latency and energy consumption between the computation and the communication subsystems are studied. It is shown that the load of the communication subsystem and that of the computation subsystem should be balanced. Increasing the resource of the highly loaded subsystem can significantly reduce the required resource of the other subsystem. An algorithm is proposed to find out the optimal processing speed and the optimal number of active base stations that minimizes the overall energy consumption while assuring the requirements on the mean service latency.

  • 23.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy-Efficient Resource Allocation in Multi-Carrier NOMA SystemsManuscript (preprint) (Other academic)
    Abstract [en]

    5G cellular networks are expected to support heterogeneous services with the same level of energy dissipation as current cellular networks. As a key enabler of 5G [1], the energy efficiency performance of non-orthogonal multiple access (NOMA) is of paramount importance. In NOMA systems, the system performance, e.g., spectral efficiency and energy efficiency are largely affected by resource allocation, i.e., sub-carrier assignment and power allocation. This paper studies the joint sub-carrier assignment and power allocation for the downlink transmission of multi-carrier NOMA systems to maximize the system energy efficiency (SEE). We first formulate an energyefficiency maximization problem while assuring the connectivity requirements of all users. The original optimization problem is a mixed integer programming problem and is NP hard. In order to develop optimal solutions with low complexity, the formulated problem is decomposed into three sub-problems: sub-carrier assignment, power allocation across sub-carriers and power allocation among users sharing the same sub-carrier. Given subcarrier assignment, we first obtain the optimal power allocation among users on one sub-carrier and then the optimal power allocation across sub-carriers. To find the optimal sub-carrier assignment, a greedy search solution based on the intrinsic structure of the transmitted power is proposed to minimize the overall required power to support the connectivity requirements of all users. Numerical simulations are implemented to validate the analytical findings. The results show that our proposed algorithms achieve better system energy efficiency and lower user blocking rate than the state-of-the-art solutions in the literature.

  • 24.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Interference-aware Distributed Control of Cell Discontinuous Transmission2018In: 2018 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

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

  • 25.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Interference-aware distributed control of cell discontinuous transmission2018In: 2018 IEEE Wireless Communications and Networking Conference (WCNC), 2018Conference paper (Refereed)
    Abstract [en]

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

  • 26.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Optimal Operation of Base Stations With Deep Sleep and Discontinuous TransmissionIn: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359Article in journal (Refereed)
    Abstract [en]

    Traffic-aware base station (BS) sleeping is a promising approach to increase the energy efficiency (EE) of cellular networks. Both deep sleep and discontinuous transmission (DTX)can be applied to improve network EE. This paper studies the optimal BS operation when both deep sleep and DTX are employed. Queuing theory and stochastic geometry theory are jointly applied to model network performance considering both traffic dynamics and stochastic channel quality. We firstly propose a scaling law of transmit power that assures network coverage. Then, we characterize the resource utilization of active BSs when various percent-ages of BSs are switched into deep sleep, and analyze the overload probability of the remaining active BSs. Finally, we investigate the impact of BS deep sleep and DTX micro sleep on network EE. Both analytical and simulation results show that there is a trade-off between deep sleep and DTX micro sleep. Switching BSs into deep sleep would increase the load of the remaining active BSs and reduce their energy saving achieved with DTX. When the power consumption of BS in DTX micro-sleep mode is considerably low, switching BSs into deep sleep might increase the overall energy consumption, and it is not always the best practice to switch as many BSs into deep sleep as possible to maximize network EE.

  • 27.
    Chang, Peiliang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Resource Provision for Energy-Efficient Mobile Edge Computing2018In: IEEE Globecom 2018, IEEE Communications Society, 2018Conference paper (Refereed)
    Abstract [en]

    Mobile Edge Computing (a.k.a Fog computing) is recently proposed to provide computing service for delaysensitive mobile applications. Despite various benefits, deploying edge servers in cellular networks would increase their energy consumption. In this paper, we investigate the provision of resources, including both communication and computation resources, of Mobile Edge Computing (MEC) systems to improve their energy efficiency (EE). In a MEC system, both the communication subsystem, which allows mobile users to access Internet and offload their computing tasks, and the computation subsystem, which accomplishes the offloaded computing tasks, affect the service latency and consume energy. Modelling the whole system as tandem queues, we study the trade-offs between these two subsystems on energy consumption and service latency. Based on the analysis results, we propose an algorithm to determine the optimal provision of both communication and computation resources to minimize the overall energy consumption without sacrificing the performance on service latency. Numerical results are provided to validate our analytical findings.

  • 28. Chen, X.
    et al.
    Lin, R.
    Cui, J.
    Gan, L.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Ozolins, O.
    Udalcovs, A.
    Jiang, T.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Tang, M.
    Fu, S.
    Liu, D.
    TDHQ Enabling Fine-Granularity Adaptive Loading for SSB-DMT Systems2018In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 30, no 19, p. 1687-1690, article id 8443443Article in journal (Refereed)
    Abstract [en]

    In this letter, we introduce time domain hybrid quadrature amplitude modulation (TDHQ) for the single sideband discrete multi-tone systems. The experimental results reveal that with a single precoding set and the proposed adaptive loading algorithm, the TDHQ scheme can achieve finer granularity and therefore smoother continuous growth of data rate than that with the conventional quadrature amplitude modulation. Besides, thanks to the frame construction and the tailored mapping rule, the scheme with TDHQ has an obviously better peak to an average power ratio. 

  • 29.
    Chiesa, Marco
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab). Université Catholique de Louvain, Belgium.
    Demmler, D.
    Canini, M.
    Schapira, M.
    Schneider, T.
    SIXPACK: Securing internet eXchange points against curious onlookers2017In: CoNEXT 2017 - Proceedings of the 2017 13th International Conference on emerging Networking EXperiments and Technologies, Association for Computing Machinery (ACM), 2017, p. 120-133Conference paper (Refereed)
    Abstract [en]

    Internet eXchange Points (IXPs) play an ever-growing role in Internet inter-connection. To facilitate the exchange of routes amongst their members, IXPs provide Route Server (RS) services to dispatch the routes according to each member's peering policies. Nowadays, to make use of RSes, these policies must be disclosed to the IXP. This poses fundamental questions regarding the privacy guarantees of route-computation on confidential business information. Indeed, as evidenced by interaction with IXP administrators and a survey of network operators, this state of affairs raises privacy concerns among network administrators and even deters some networks from subscribing to RS services. We design sixpack1, an RS service that leverages Secure Multi-Party Computation (SMPC) to keep peering policies confidential, while extending, the functionalities of today's RSes. As SMPC is notoriously heavy in terms of communication and computation, our design and implementation of sixpack aims at moving computation outside of the SMPC without compromising the privacy guarantees. We assess the effectiveness and scalability of our system by evaluating a prototype implementation using traces of data from one of the largest IXPs in the world. Our evaluation results indicate that sixpack can scale to support privacy-preserving route-computation, even at IXPs with many hundreds of member networks.

  • 30.
    Chiesa, Marco
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Retvari, Gabor
    MTA BME Informat Syst Res Grp, H-1521 Budapest, Hungary..
    Schapira, Michael
    Hebrew Univ Jerusalem, IL-9190401 Jerusalem, Israel..
    Oblivious Routing in IP Networks2018In: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 26, no 3, p. 1292-1305Article in journal (Refereed)
    Abstract [en]

    To optimize the flow of traffic in IP networks, operators do traffic engineering (TE), i.e., tune routing-protocol parameters in response to traffic demands. TE in IP networks typically involves configuring static link weights and splitting traffic between the resulting shortest-paths via the equal-cost-multipath (ECMP) mechanism. Unfortunately, ECMP is a notoriously cumbersome and indirect means for optimizing traffic flow, often leading to poor network performance. Also, obtaining accurate knowledge of traffic demands as the input to TE is a non-trivial task that may require additional monitoring infrastructure, and traffic conditions can be highly variable, further complicating TE. We leverage recently proposed schemes for increasing ECMP's expressiveness via carefully disseminated bogus information (lies) to design COYOTE, a readily deployable TE scheme for robust and efficient network utilization. COYOTE leverages new algorithmic ideas to configure (static) traffic splitting ratios that are optimized with respect to all (even adversarial) traffic scenarios within the operator's "uncertainty bounds". Our experimental analyses show that COYOTE significantly outperforms today's prevalent TE schemes in a manner that is robust to traffic uncertainty and variation. We discuss experiments with a prototype implementation of COYOTE.

  • 31.
    da Silva, Carlos Natalino
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Chiaraviglio, Luca
    Idzikowski, Filip
    Wosinska, Lena
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Monti, Paolo
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Joint Optimization of Failure Management Costs, Electricity Costs, and Operator Revenue in Optical Core Networks2017In: IEEE Transactions on Green Communications and Networking, ISSN 2473-2400, Vol. PP, no 99Article in journal (Refereed)
    Abstract [en]

    We focus on the problem of maximizing profitability in an optical core network by acting on the power states of Optical Line Amplifiers (OLAs) and Line Cards (LCs) operating under varying traffic. Specifically, the profitability metric considered in this work takes into account the electricity costs of OLAs and LCs, the failure management costs derived from the application of power states to the network devices, and the operator revenue. After proving that all terms of the considered profitability function are deeply inter-correlated, we formulate the optimization problem of maximizing the network profitability in an optical core network with multi-period traffic. By solving the proposed formulation on a realistic scenario, we show that it is possible to wisely trade between the considered costs and revenue, and achieve higher network profitability than in the case in which the single terms are considered in isolation, e.g., only electricity consumption or only Failure Management Costs (FMC).

  • 32.
    Friðriksson, Vilhelm
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Container overhead in microservice systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Containers have been gaining popularity in recent years due to their ability to provide higher flexibility, higher reliability and dynamic scalability to enterprise software systems. In order to fully utilize containers, software developers aim to build their software using microservice architecture, meaning that instead of working on a single large codebase for the whole project, the software is split into smaller units. These microservices can be deployed in their own container instead of the traditional virtual machine setup where a server has to configured with all necessary dependencies. Moving away from the monolithic software architecture to containerized microservices is bound to bring performance penalties due to increased network calls between services and container overhead. The integration must therefor be carefully planned in order to fully utilize the container setup while minimizing the overhead. The purpose of this thesis project was to measure how much overhead can be expected due to containers in an enterprise environment. By using a combination of virtual machines and Docker containers, a microservice system was deployed with four different deployment strategies and the system’s performance was measured by analyzing request response times under various loads. The services were made to run on a single server and on multiple servers, with and without Docker. The performance measurements showed that the system performed worse in every case when Docker was used. Furthermore, the results showed that Docker can have significant negative impact on performance when there is a heavy load on the system.

  • 33.
    Gimenez, Jordi Joan
    et al.
    Univ Politecn Valencia, iTEAM Res Inst, E-46022 Valencia, Spain..
    Sung, Ki Won
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Gomez-Barquero, David
    Univ Politecn Valencia, iTEAM Res Inst, E-46022 Valencia, Spain..
    Semianalytical Approach to the PDF of SINR in HPHT and LPLT Single-Frequency Networks2018In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 5, p. 4173-4181Article in journal (Refereed)
    Abstract [en]

    Single-frequency networks (SFN) are widely adopted in terrestrial broadcast networks based on high-power high-tower (HPHT) deployments. The mobile broadcasting standard Evolved Multimedia Broadcast Multicast Service (eMBMS) has been enhanced in Release 14 to enable SFN operation with larger CP duration which may allow for the deployment of large area SFNs and even the combined operation between HPHT and low-power low-tower (LPLT) cellular stations. The knowledge of the signal-to-interference-plus-noise ratio (SINR) distribution over an SFN area may facilitate the selection of transmission parameters according to the network topology. This paper presents a semianalytical method for the calculation of the SINR distribution in SFNs with low computational complexity compared to Monte Carlo simulations. The method, which builds on previous work developed for cellular communications, is applied to HPHT+LPLT SFNs and evaluated against different transmission and network parameters.

  • 34. Gong, Y.
    et al.
    Yang, B.
    Zhang, D.
    Hong, X.
    Lu, Y.
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering. South China Normal University, Guangzhou, China.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab). South China Normal University, Guangzhou, China.
    Crosstalk-aware multiple-AWG based optical interconnects for datacenter networks2018In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 426, p. 151-157Article in journal (Refereed)
    Abstract [en]

    This paper proposes a crosstalk-aware passive optical interconnect architecture based on multiple arrayed waveguide gratings (AWGs). With two-stage cascaded AWGs, it can realize the communications not only within but also among the clusters for large-scale datacenters. To overcome serious crosstalk in multiple-AWG based optical interconnects, crosstalk suppression schemes are proposed. Proof-of-concept experiments are carried out to verify the necessity and feasibility of the proposed crosstalk suppression schemes for multiple-AWG based optical interconnects.

  • 35. Goscien, R.
    et al.
    Natalino, Carlos
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Furdek, Marija
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Impact of high-power jamming attacks on SDM networks2018In: 22nd Conference on Optical Network Design and Modelling, ONDM 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 77-81Conference paper (Refereed)
    Abstract [en]

    Space Division Multiplexing (SDM) is a promising solution to provide ultra-high capacity optical network infrastructure for rapidly increasing traffic demands. Such network infrastructure can be a target of deliberate attacks that aim at disrupting a large number of vital services. This paper assesses the effects of high-power jamming attacks in SDM optical networks utilizing Multi-Core Fibers (MCFs), where the disruptive effect of the inserted jamming signals may spread among multiple cores due to increased Inter-Core CrossTalk (ICo-XT). We first assess the jamming-induced reduction of the signal reach for different bit rates and modulation formats. The obtained reach limitations are then used to derive the maximal traffic disruption at the network level. Results indicate that connections provisioned satisfying the normal operating conditions are highly vulnerable to these attacks, potentially leading to huge data losses at the network level.

  • 36.
    Hong, Xuezhi
    et al.
    KTH Royal Inst Technol, Sch ICT, Kista, Sweden.;South China Normal Univ, ZJU SCNU Joint Res Ctr Photon, Guangzhou, Guangdong, Peoples R China..
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab). KTH Royal Inst Technol, Sch ICT, Kista, Sweden.;RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Guo, Changjian
    South China Normal Univ, ZJU SCNU Joint Res Ctr Photon, Guangzhou, Guangdong, Peoples R China..
    Nordwall, Fredrik
    Tektronix AB, Stockholm, Sweden..
    Engenhardt, Klaus M.
    Tektronix GmbH, Stuttgart, Germany..
    Kakkar, Aditya
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Rodrigo Navarro, Jaime
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Westergren, Urban
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Xiao, Shilin
    Shanghai Jiao Tong Univ, State Key Lab Adv Opt Commun Syst & Networks, Shanghai, Peoples R China..
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    200-Gbps DMT Transmission over 1.6-km SSMF with A Single EML/DAC/PD for Optical Interconnects at C-Band2017In: 43RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC 2017), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We report on the first experimental demonstration of 200-Gbps (net rate 166.7-Gbps) 1.55-mu m DMT IMDD transmission over 1.6 km fiber using a single monolithically-integrated-EML, DAC and photodiode, achieving an effective electrical spectrum efficiency of 4.93 bit/s/Hz.

  • 37.
    Hossain, Mohammad Istiak
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH Royal Inst Technol, Sch Informat & Commun Technol, Stockholm, Sweden..
    IoT-Communications as a Service: Actor Roles on Indoor Wireless Coverage2017In: 2017 JOINT 13TH CTTE AND 10TH CMI CONFERENCE ON INTERNET OF THINGS - BUSINESS MODELS, USERS, AND NETWORKS / [ed] Falch, M, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Internet of Things (IoT) is anticipated as a 'game changer' for communication service providers. Numerous IoT devices will deploy in areas where humans already inhabit. It is increasing the importance of indoor area coverage to support IoT services. This again brings the historically important questions, 'what roles an actor play and who will control the indoor coverage?' In this paper, we discuss the business actors' roles in IoT indoor service context. We identify the possible roles and activities needed to provide end-to-end indoor IoT services. Additionally, we analyze the actors' roles in IoT ecosystem. We compare the actors' roles in the context of the suitable technology and deployment choices. Our identification of roles and initial analysis shows the impact of technology and rollout choices over network business strategy. With our presented analysis, we evaluate the possible paths for mobile network operators (MNOs) on low-power wide area (LPWAN) or low-power wireless local area (LPWLAN) network deployment.

  • 38.
    Jan, Jonathan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Collecting Data for Building Automation Analytics: A case study for collecting operational data with minimal human intervention2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Approximately 40% of the total energy consumption within the EU is due to buildings, and similar numbers can be found in the US. If the principal inefficiencies in buildings were easily identifiable, then a facility manager could focus their resources to make the buildings more efficient, which would lead to both cost savings for the facility owners and decrease the building’s ecological footprint.

    In building automation systems today, data is already being collected every second, but due to the lack of standardization for describing this data, having access to data is not the same as being able to make use of it. The existing heterogeneity makes it very costly to gather data from multiple buildings, thus making it difficult to understand the big picture.

    Facility managers cannot fix what they cannot see; thus it is important to facilitate the visualization of the data collected from all of the different building automation systems. This potentially offers great benefits with regards to both sustainability and economy. In this thesis, the author’s goal is to propose a sustainable, cost and time effective data integration strategy for real estate owners who wish to gain greater insight into their buildings’ efficiency. The study begins with a literature study to find previous and on-going attempts to solve this problem. Some initiatives for standardization of semantic models were found. Two of these models, Brick and Haystack, were chosen. One building automation system (BAS) was tested in a pilot case study, to test the appropriateness of a solution.

    The key results from this thesis project show that data from building automation systems, can be integrated into an analysis platform, and an extract, transform, and load (ETL) process for this is presented. How time efficiently data can be tagged and transformed into a common format is very dependent upon the current control system’s data storage format and whether information about its structure is adequate. It is also noted that there is no guarantee that facility managers have access to the control system’s database or information about how that is structured, in such cases other techniques can be used such as BACnet/IP, or Open Platform Communications (OPC) Unified Architecture.

  • 39. Jia, S.
    et al.
    Wang, S.
    Liu, K.
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Zhang, H.
    Jin, X.
    Zheng, S.
    Chi, H.
    Zhang, X.
    Yu, X.
    A unified system with integrated generation of high-speed communication and high-resolution sensing signals based on THz photonics2018In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 36, no 19, p. 4549-4556, article id 8425966Article in journal (Refereed)
    Abstract [en]

    Multifunctional convergence is one of the key physical features in future generation networks and Internet of things architectures. In this paper, we propose and experimentally demonstrate a unified terahertz (THz) system operating in the 300 GHz band, with a potential of simultaneously enabling high-speed communication and high-resolution ranging over a common optical infrastructure. Both THz communication and THz sensing signals are generated based on THz photonics and cutting-edge terahertz transceiver technologies. In the experiment, 16-quadrature amplitude modulation modulated THz signal is generated by photo-mixing two free running lasers for the communication, and linear frequency modulated (LFM) THz pulses are generated based on optical interferometer-based frequency-to-time mapping (FTM) for sensing. The experimental results show that up to 56 Gbit/s net rate is successfully transmitted over a 2 m free-space line-of-sight link, and the THz LFM pulses with a time-bandwidth product of up to 207 are successfully generated, which is potentially able to enable a cm-scale range resolution. We also investigate the frequency multiplexing schemes for two signals by changing the channel gap at the transmitter side. To the best of our knowledge, such a system represents the first demonstration of integrated generation system in the THz region above 300 GHz, which has great potential in prospective applications of future converged networks. 

  • 40.
    Karapantelakis, Athanasios
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Challenges for ICT Business Development in Intelligent Transport Systems2017In: 2017 JOINT 13TH CTTE AND 10TH CMI CONFERENCE ON INTERNET OF THINGS - BUSINESS MODELS, USERS, AND NETWORKS / [ed] Falch, M, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    Intelligent Transportation Systems (ITS) are a product of convergence of Information and Communication Technology (ICT) and transport industries, with an aim to improve safety, mobility and efficiency of transportation. Ubiquitous, fast and inexpensive wireless communication and increasing vehicle computation, storage and sensing capabilities, are technological enablers for ITS. Notwithstanding technological maturity, the real challenge rises from the change the ITS market brings to the business of ICT players, as development of ITS services requires cooperation of multiple actors across industries. For ICT players, this signifies a departure from rigid telecom-era business models to a more networked structure of collaboration with other players. In this paper, we identify key business challenges that ICT players face in ITS market, by analysis of two ITS use cases.

  • 41.
    Katsikas, Georgios P.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab). RISE SICS.
    NFV Service Chains at the Speed of the Underlying Commodity Hardware2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Link speeds in networks will in the near-future reach and exceed 100 Gbps. While available specialized hardware can accommodate these speeds, modern networks have adopted a new networking paradigm, also known as Network Functions Virtualization (NFV), that replaces expensive specialized hardware with open-source software running on commodity hardware. However, achieving high performance using commodity hardware is a hard problem mainly because of the processor-memory gap. This gap suggests that only the fastest memories of today’s commodity servers can achieve the desirable access latencies for high speed networks. Existing NFV systems realize chained network functions (also known as service chains) mostly using slower memories; this implies a need for multiple additional CPU cores or even multiple servers to achieve high speed packet processing. In contrast, this thesis combines four contributions to realize NFV service chains with dramatically higher performance and better efficiency than the state of the art.

    The first contribution is a framework that profiles NFV service chains to uncover reasons for performance degradation, while the second contribution leverages the profiler’s data to accelerate these service chains by combining multiplexing of system calls with scheduling strategies. The third contribution synthesizes input/output and processing service chain operations to increase the spatial locality of network traffic with respect to a system’s caches. The fourth contribution combines the profiler’s insights from the first contribution and the synthesis approach of the third contribution to realize NFV service chains at the speed of the underlying commodity hardware. To do so, stateless traffic classification operations are offloaded into available hardware (i.e., programmable switches and/or network cards) and a tag is associated with each traffic class. At the server side, input traffic classes are classified by the hardware based upon the values of these tags, which indicate the CPU core that should undertake their stateful processing, while ensuring zero inter-core communication.

    With commodity hardware, this thesis realizes Internet Service Provider-level service chains and deep packet inspection at a line-rate 40 Gbps and stateful service chains at the speed of a 100 GbE network card on a 16 core single server. This results in up to (i) 4.7x lower latency, (ii) 8.5x higher throughput, and (iii) 6.5x better efficiency than the state of the art. The techniques described in this thesis are crucial for realizing future high speed NFV deployments.

  • 42.
    Katsikas, Georgios P.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab). RISE SICS.
    Barbette, Tom
    University of Liege.
    Kostic, Dejan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Steinert, Rebecca
    RISE SICS.
    Maguire Jr., Gerald Q.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Metron: NFV Service Chains at the True Speed of the Underlying Hardware2018Conference paper (Refereed)
    Abstract [en]

    In this paper we present Metron, a Network Functions Virtualization (NFV) platform that achieves high resource utilization by jointly exploiting the underlying network and commodity servers’ resources. This synergy allows Metron to: (i) offload part of the packet processing logic to the network, (ii) use smart tagging to setup and exploit the affinity of traffic classes, and (iii) use tag-based hardware dispatching to carry out the remaining packet processing at the speed of the servers’ fastest cache(s), with zero inter-core communication. Metron also introduces a novel resource allocation scheme that minimizes the resource allocation overhead for large-scale NFV deployments. With commodity hardware assistance, Metron deeply inspects traffic at 40 Gbps and realizes stateful network functions at the speed of a 100 GbE network card on a single server. Metron has 2.75-6.5x better efficiency than OpenBox, a state of the art NFV system, while ensuring key requirements such as elasticity, fine-grained load balancing, and flexible traffic steering.

  • 43.
    Khodaei, Mohammad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Jin, Hongyu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    SECMACE: Scalable and Robust Identity and Credential Management Infrastructure in Vehicular Communication Systems2018In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 19, no 5, p. 1430-1444Article in journal (Refereed)
    Abstract [en]

    Several years of academic and industrial research efforts have converged to a common understanding on fundamental security building blocks for the upcoming vehicular communication (VC) systems. There is a growing consensus toward deploying a special-purpose identity and credential management infrastructure, i.e., a vehicular public-key infrastructure (VPKI), enabling pseudonymous authentication, with standardization efforts toward that direction. In spite of the progress made by standardization bodies (IEEE 1609.2 and ETSI) and harmonization efforts [Car2Car Communication Consortium (C2C-CC)], significant questions remain unanswered toward deploying a VPKI. Deep understanding of the VPKI, a central building block of secure and privacy-preserving VC systems, is still lacking. This paper contributes to the closing of this gap. We present SECMACE, a VPKI system, which is compatible with the IEEE 1609.2 and ETSI standards specifications. We provide a detailed description of our state-of-the-art VPKI that improves upon existing proposals in terms of security and privacy protection, and efficiency. SECMACE facilitates multi-domain operations in the VC systems and enhances user privacy, notably preventing linking pseudonyms based on timing information and offering increased protection even against honest-but-curious VPKI entities. We propose multiple policies for the vehicle-VPKI interactions and two large-scale mobility trace data sets, based on which we evaluate the full-blown implementation of SECMACE. With very little attention on the VPKI performance thus far, our results reveal that modest computing resources can support a large area of vehicles with very few delays and the most promising policy in terms of privacy protection can be supported with moderate overhead.

  • 44.
    Kim, Donggu
    et al.
    Korea Adv Inst Sci & Technol, Sch Elect Engn, Daejeon 34141, South Korea..
    Yang, Yanpeng
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Kang, Joonhyuk
    Korea Adv Inst Sci & Technol, Sch Elect Engn, Daejeon 34141, South Korea..
    Cooperation Strategies for Partly Wireless C-RAN2018In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 22, no 6, p. 1248-1251Article in journal (Refereed)
    Abstract [en]

    This letter presents a variant of cloud radio access network (C-RAN) architecture, which we term partly wireless C-RAN (PW-CRAN). It is characterized by extra radio nodes connected through the existing remote radio heads. Because of the newly connected nodes and the consequent additional delay, the operation of PW-CRAN requires different approaches compared with that of the typical C-RAN. Specifically, the effect of delayed channel state information on the suitability of network cooperation should be identified. To tackle this problem, we introduce two representative cooperation strategies and evaluate the performance with regard to the delay via simulations. Numerical results suggest that it is better to exclude the extra nodes from cooperation if they incur excess delay. Furthermore, whether the delay is deemed excessive depends on the interference environment. Hence, we provide quantified guidelines on the cooperation strategy of PW-CRAN.

  • 45.
    Kokkalis, Andreas
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    On-demand virtual laboratory environments for Internetworking e-learning: A first step using docker containers2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Learning Management Systems (LMSs) are widely used in higher education to improve the learning, teaching, and administrative tasks for both students and instructors. Such systems enrich the educational experience by integrating a wide range of services, such as on-demand course material and training, thus empowering students to achieve their learning outcomes at their own pace.

    Courses in various sub-fields of Computer Science that seek to provide rich electronic learning (e-learning) experience depend on exercise material being offered in the forms of quizzes, programming exercises, laboratories, simulations, etc. Providing hands on experience in courses such as Internetworking could be facilitated by providing laboratory exercises based on virtual machine environments where the student studies the performance of different internet protocols under different conditions (such as different throughput bounds, error rates, and patterns of changes in these conditions). Unfortunately, the integration of such exercises and their tailored virtual environments is not yet very popular in LMSs.

    This thesis project investigates the generation of on-demand virtual exercise environments using cloud infrastructures and integration with an LMS to provide a rich e-learning in an Internetworking course. The software deliverable of this project enables instructors to dynamically instantiate virtual laboratories without incurring the overhead of running and maintaining their own physical infrastructure. This sets the foundations for a virtual classroom that can scale in response to higher system utilization during specific periods of the academic calendar.

  • 46.
    Laya, Andrés
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Markendahl, Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Lundberg, Stefan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Network-centric business models for health, social care and wellbeing solutions in the internet of things2018In: Scandinavian Journal of Management, ISSN 0956-5221, E-ISSN 1873-3387, Vol. 34, no 2, p. 103-116Article in journal (Refereed)
    Abstract [en]

    In this multiple case study we analyze solutions based on connected devices in the context of health, social care and wellbeing. Based on the consideration that a solution is a combination of services and products, we build on the notion that business models can be studied at a firm-level and also at a network-level. The network-level analysis is used to motivate the reasons why solutions emerging at the intersection of the healthcare and the ICT industries benefit from collaboration among different actors. We conclude that the firm- and the network-level development of business models provide alignment in the business network and are useful to establish the relation that technological component have with overall solutions. Our findings suggest that some component bring novelty in the final offer without affecting the ongoing operation, while other component aim at improving the internal working processes, with minimal effects on the final offer to end users. We discuss the benefits of a network-level perspective for each case.

  • 47.
    Lin, Rui
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Lu, Yang
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Cheng, Yuxin
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Jacobsen, Gunnar
    RISE Acreo AB, Networking & Transmiss Lab, SE-16425 Kista, Sweden..
    Tang, Ming
    Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China..
    Liu, Deming
    Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China..
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    First Experimental Demonstration of Physical-Layer Network Coding in PAM4 System for Passive Optical Interconnects2017In: 43RD EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC 2017), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    We propose to implement physical-layer network coding (PLNC) in coupler-based passive optical interconnects. The PLNC over PAM4 system is for the first time experimentally validated, where simultaneous mutual communications can be kept within the same wavelength channel, doubling spectrum efficiency.

  • 48.
    Lin, Rui
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Pang, Xiaodan
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Van Kerrebrouck, J.
    Belgium.
    Verplaetse, M.
    Belgium.
    Ozolins, O.
    Udalcovs, A.
    Zhang, Lu
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Gan, L.
    China.
    Tang, M.
    China.
    Fu, S.
    China.
    Schatz, Richard
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Westergren, Urban
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Liu, D.
    China.
    Tong, W.
    China.
    De Keulenaer, T.
    Belgium.
    Torfs, G.
    Belgium.
    Bauwelinck, J.
    Belgium.
    Yin, X.
    Belgium.
    Chen, Jiajia
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Real-time 100 Gbps/λ/core NRZ and EDB IM/DD transmission over 10 km multicore fiber2018In: Optics InfoBase Conference Papers, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    A BiCMOS chip-based real-time IM/DD spatial division multiplexing system is experimentally demonstrated for short-reach communications. 100 Gbps/λ/core NRZ and EDB transmission is achieved below 7%-overhead HD-FEC limit after 10km 7-core fiber with optical dispersion compensation.

  • 49.
    Liu, Fei
    et al.
    Rhein Westfal TH Aachen, Inst Networked Syst, D-52072 Aachen, Germany..
    Petrova, Marina
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Dynamic Power Allocation for Downlink Multi-Carrier NOMA Systems2018In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 22, no 9, p. 1930-1933Article in journal (Refereed)
    Abstract [en]

    In this letter, the performance of optimal dynamic power allocation (PA) is analyzed for downlink multi-carrier non-orthogonal multiple access (MC-NOMA) systems. We study the PA optimization problem with a pair of users and weighted-sum-rate utility. A novel low-complexity algorithm is designed to solve the problem with a closed-form PA expression. The analytical data rate performance is derived and verified by simulation results. The numerical results indicate that a large difference in user channel states improves performance by enhancing the user diversity gain in NOMA systems. Moreover, the channel diversity gain can be achieved by multi-carrier transmission and increases with the number of subcarriers. Finally, the number of subcarriers for dynamic PA in MC-NOMA systems is discussed for practical applications.

  • 50.
    Liu, Fei
    et al.
    Rhein Westfal TH Aachen, Inst Networked Syst, D-52072 Aachen, Germany..
    Petrova, Marina
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Performance of Proportional Fair Scheduling for Downlink PD-NOMA Networks2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 10, p. 7027-7039Article in journal (Refereed)
    Abstract [en]

    In this paper, we present an analytical model for performance analysis of dynamic proportional fair scheduling (PFS) in downlink power-domain non-orthogonal multiple access (PD-NOMA) networks. In order to develop a tractable model of analytical performance, we relax the condition in the PFS optimization problem and assume an ideal NOMA system with an arbitrary number of multiplexed users per frame. We derive a closed-form solution of the optimal power allocation for the relaxed problem and design a low-complexity algorithm for joint power allocation and user set selection. With this optimal solution, the transmission performance in the ideal NOMA system is proved to be an upper bound. Based on our derivation, we develop an analytical model of the upper bound throughput performance. The analytical performance is used to estimate user data rates and overall throughput in practical NOMA systems. We conduct system-level simulations to evaluate the accuracy of our data rate estimation. The simulation results verify our analysis of the upper bound performance of PFS in NOMA systems and confirm that using its analytical results for data rate estimation guarantees high accuracy. The impact of partial and imperfect channel state information on the estimation performance is investigated as well.

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