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  • 251.
    Arad, Cosmin Ionel
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    Programming Model and Protocols for Reconfigurable Distributed Systems2013Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Distributed systems are everywhere. From large datacenters to mobile devices, an ever richer assortment of applications and services relies on distributed systems, infrastructure, and protocols. Despite their ubiquity, testing and debugging distributed systems remains notoriously hard. Moreover, aside from inherent design challenges posed by partial failure, concurrency, or asynchrony, there remain significant challenges in the implementation of distributed systems. These programming challenges stem from the increasing complexity of the concurrent activities and reactive behaviors in a distributed system on the one hand, and the need to effectively leverage the parallelism offered by modern multi-core hardware, on the other hand.

    This thesis contributes Kompics, a programming model designed to alleviate some of these challenges. Kompics is a component model and programming framework for building distributed systems by composing message-passing concurrent components. Systems built with Kompics leverage multi-core machines out of the box, and they can be dynamically reconfigured to support hot software upgrades. A simulation framework enables deterministic execution replay for debugging, testing, and reproducible behavior evaluation for largescale Kompics distributed systems. The same system code is used for both simulation and production deployment, greatly simplifying the system development, testing, and debugging cycle.

    We highlight the architectural patterns and abstractions facilitated by Kompics through a case study of a non-trivial distributed key-value storage system. CATS is a scalable, fault-tolerant, elastic, and self-managing key-value store which trades off service availability for guarantees of atomic data consistency and tolerance to network partitions. We present the composition architecture for the numerous protocols employed by the CATS system, as well as our methodology for testing the correctness of key CATS algorithms using the Kompics simulation framework.

    Results from a comprehensive performance evaluation attest that CATS achieves its claimed properties and delivers a level of performance competitive with similar systems which provide only weaker consistency guarantees. More importantly, this testifies that Kompics admits efficient system implementations. Its use as a teaching framework as well as its use for rapid prototyping, development, and evaluation of a myriad of scalable distributed systems, both within and outside our research group, confirm the practicality of Kompics.

  • 252.
    Aragon, Santiago
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS. Technische Universität Darmstadt, Germany.
    Tiloca, Marco
    RISE - Research Institutes of Sweden, ICT, SICS.
    Maass, Max
    Technische Universität Darmstadt, Germany.
    Hollick, Matthias
    Technische Universität Darmstadt, Germany.
    Raza, Shahid
    RISE - Research Institutes of Sweden, ICT, SICS.
    ACE of Spades in the IoT Security Game: A Flexible IPsec Security Profile for Access Control2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Authentication and Authorization for ConstrainedEnvironments (ACE) framework provides fine-grainedaccess control in the Internet of Things, where devices areresource-constrained and with limited connectivity. The ACEframework defines separate profiles to specify how exactlyentities interact and what security and communication protocolsto use. This paper presents the novel ACE IPsec profile, whichspecifies how a client establishes a secure IPsec channel witha resource server, contextually using the ACE framework toenforce authorized access to remote resources. The profilemakes it possible to establish IPsec Security Associations, eitherthrough their direct provisioning or through the standardIKEv2 protocol. We provide the first Open Source implementationof the ACE IPsec profile for the Contiki OS and testit on the resource-constrained Zolertia Firefly platform. Ourexperimental performance evaluation confirms that the IPsecprofile and its operating modes are affordable and deployablealso on constrained IoT platforms.

  • 253.
    Arain, Muhammad Asif
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Havoutis, Ioannis
    Department of Advanced Robotics, Istituto Italiano di Tecnologia, Genova, Italy.
    Semini, Claudio
    Department of Advanced Robotics,Istituto Italiano di Tecnologia, Genova, Italy.
    Buchli, Jonas
    Eidgenössische Technische Hochschule Zürich (ETH), Zurich, Schweiz.
    Caldwell, Darwin G.
    Department of Advanced Robotics, Istituto Italiano di Tecnologia, Genova, Italy.
    A comparison of search-based planners for a legged robot2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Path planning for multi-DoF legged robots is achallenging task due to the high dimensionality and complexityof the planning space. We present our first attempt to builda path planning framework for the hydraulic quadruped -HyQ. Our approach adopts a similar strategy to [1], whereplanning is divided into a task-space and a joint-space part.The task-space planner finds a path for the center of gravity(COG) of the robot, while then the footstep planner generates theappropriate footholds under reachability and stability criteria.Next the joint-space planner translates the task-space COGtrajectories into robot joint angles. We present a comparisonof a set of search-based planning algorithms; Dijkstra, A* andARA*, and evaluate these over a set of given terrains and anumber of varying start and end points. All test runs supportthat our approach is a simple yet robust solution. We reportcomparisons in path length, computation time, and path cost,between the aforementioned planning algorithms.

  • 254.
    Arain, Muhammad Asif
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Schaffernicht, Erik
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Hernandez Bennetts, Victor
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Lilienthal, Achim J.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    The Right Direction to Smell: Efficient Sensor Planning Strategies for Robot Assisted Gas Tomography2016Ingår i: 2016 IEEE International Conference on Robotics and Automation (ICRA), New York, USA: IEEE Robotics and Automation Society, 2016, s. 4275-4281Konferensbidrag (Refereegranskat)
    Abstract [en]

    Creating an accurate model of gas emissions is an important task in monitoring and surveillance applications. A promising solution for a range of real-world applications are gas-sensitive mobile robots with spectroscopy-based remote sensors that are used to create a tomographic reconstruction of the gas distribution. The quality of these reconstructions depends crucially on the chosen sensing geometry. In this paper we address the problem of sensor planning by investigating sensing geometries that minimize reconstruction errors, and then formulate an optimization algorithm that chooses sensing configurations accordingly. The algorithm decouples sensor planning for single high concentration regions (hotspots) and subsequently fuses the individual solutions to a global solution consisting of sensing poses and the shortest path between them. The proposed algorithm compares favorably to a template matching technique in a simple simulation and in a real-world experiment. In the latter, we also compare the proposed sensor planning strategy to the sensing strategy of a human expert and find indications that the quality of the reconstructed map is higher with the proposed algorithm.

  • 255.
    Aramrattana, Maytheewat
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES). The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Modelling and Simulation for Evaluation of Cooperative Intelligent Transport System Functions2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Future vehicles are expected to be equipped with wireless communication tech- nology, that enables them to be “connected” to each others and road infras- tructures. Complementing current autonomous vehicles and automated driving systems, the wireless communication allows the vehicles to interact, cooperate, and be aware of its surroundings beyond their own sensors’ range. Such sys- tems are often referred to as Cooperative Intelligent Transport Systems (C-ITS), which aims to provide extra safety, efficiency, and sustainability to transporta- tion systems. Several C-ITS applications are under development and will require thorough testing and evaluation before their deployment in the real-world. C- ITS depend on several sub-systems, which increase their complexity, and makes them difficult to evaluate.

    Simulations are often used to evaluate many different automotive appli- cations, including C-ITS. Although they have been used extensively, simulation tools dedicated to determine all aspects of C-ITS are rare, especially human fac- tors aspects, which are often ignored. The majority of the simulation tools for C-ITS rely heavily on different combinations of network and traffic simulators. The human factors issues have been covered in only a few C-ITS simulation tools, that involve a driving simulator. Therefore, in this thesis, a C-ITS simu- lation framework that combines driving, network, and traffic simulators is pre- sented. The simulation framework is able to evaluate C-ITS applications from three perspectives; a) human driver; b) wireless communication; and c) traffic systems.

    Cooperative Adaptive Cruise Control (CACC) and its applications are cho- sen as the first set of C-ITS functions to be evaluated. Example scenarios from CACC and platoon merging applications are presented, and used as test cases for the simulation framework, as well as to elaborate potential usages of it. Moreover, approaches, results, and challenges from composing the simulation framework are presented and discussed. The results shows the usefulness of the proposed simulation framework.

  • 256.
    Aramrattana, Maytheewat
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Körsimulering och visualisering, SIM. Högskolan i Halmstad.
    Modelling and Simulation for Evaluation of Cooperative Intelligent Transport System Functions2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Future vehicles are expected to be equipped with wireless communication technology, that enables them to be “connected” to each others and road infrastructures. Complementing current autonomous vehicles and automated driving systems, the wireless communication allows the vehicles to interact, cooperate, and be aware of its surroundings beyond their own sensors’ range. Such sys- tems are often referred to as Cooperative Intelligent Transport Systems (C-ITS), which aims to provide extra safety, efficiency, and sustainability to transporta- tion systems. Several C-ITS applications are under development and will require thorough testing and evaluation before their deployment in the real-world. C- ITS depend on several sub-systems, which increase their complexity, and makes them difficult to evaluate.

    Simulations are often used to evaluate many different automotive applications, including C-ITS. Although they have been used extensively, simulation tools dedicated to determine all aspects of C-ITS are rare, especially human factors aspects, which are often ignored. The majority of the simulation tools for C-ITS rely heavily on different combinations of network and traffic simulators. The human factors issues have been covered in only a few C-ITS simulation tools, that involve a driving simulator. Therefore, in this thesis, a C-ITS simulation framework that combines driving, network, and traffic simulators is presented. The simulation framework is able to evaluate C-ITS applications from three perspectives; a) human driver; b) wireless communication; and c) traffic systems.

    Cooperative Adaptive Cruise Control (CACC) and its applications are chosen as the first set of C-ITS functions to be evaluated. Example scenarios from CACC and platoon merging applications are presented, and used as test cases for the simulation framework, as well as to elaborate potential usages of it. Moreover, approaches, results, and challenges from composing the simulation framework are presented and discussed. The results shows the usefulness of the proposed simulation framework.

  • 257.
    Aramrattana, Maytheewat
    et al.
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Andersson, Anders
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Reichenberg, Frida
    RISE Viktoria, Lindholmen Science Park, Lindholmspiren 3A, Gothenburg, Sweden.
    Mellegård, Niklas
    RISE Viktoria, Lindholmen Science Park, Lindholmspiren 3A, Gothenburg, Sweden.
    Burden, Håkan
    RISE Viktoria, Lindholmen Science Park, Lindholmspiren 3A, Gothenburg, Sweden.
    Testing cooperative intelligent transport systems in distributed simulators2019Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 65, s. 206-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulation is often used as a technique to test and evaluate systems, as it provides a cost-efficient and safe alternative for testing and evaluation. A combination of simulators can be used to create high-fidelity and realistic test scenarios, especially when the systems-under-test are complex. An example of such complex systems is Cooperative Intelligent Transport Systems (C-ITS), which include many actors that are connected to each other via wireless communication in order to interact and cooperate. The majority of the actors in the systems are vehicles equipped with wireless communication modules, which can range from fully autonomous vehicles to manually driven vehicles. In order to test and evaluate C-ITS, this paper presents a distributed simulation framework that consists of (a) a moving base driving simulator; (b) a real-time vehicle simulator; and (c) network and traffic simulators. We present our approach for connecting and co-simulating the simulators. We report on limitation and performance that this simulation framework can achieve. Lastly, we discuss potential benefits and feasibility of using the simulation framework for testing of C-ITS.

  • 258.
    Aramrattana, Maytheewat
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Körsimulering och visualisering, SIM. Högskolan i Halmstad.
    Englund, Cristofer
    RISE Viktoria & Högskolan i Halmstad, CAISR Centrum för tillämpade intelligenta system (IS-lab).
    Jansson, Jonas
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF.
    Larsson, Tony
    Högskolan i Halmstad.
    Nåbo, Arne
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Körsimulering och visualisering, SIM.
    Safety Analysis of Cooperative Adaptive Cruise Control in Vehicle Cut-in Situations2017Ingår i: Proceedings of 2017 4th International Symposium on Future Active Safety Technology towards Zero-Traffic-Accidents (FAST-zero), Society of Automotive Engineers of Japan , 2017, artikel-id 20174621Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cooperative adaptive cruise control (CACC) is a cooperative intelligent transport systems (C-ITS) function, which especially when used in platooning applications, possess many expected benefits including efficient road space utilization and reduced fuel consumption. Cut-in manoeuvres in platoons can potentially reduce those benefits, and are not desired from a safety point of view. Unfortunately, in realistic traffic scenarios, cut-in manoeuvres can be expected, especially from non-connected vehicles. In this paper two different controllers for platooning are explored, aiming at maintaining the safety of the platoon while a vehicle is cutting in from the adjacent lane. A realistic scenario, where a human driver performs the cut-in manoeuvre is used to demonstrate the effectiveness of the controllers. Safety analysis of CACC controllers using time to collision (TTC) under such situation is presented. The analysis using TTC indicate that, although potential risks are always high in CACC applications such as platooning due to the small inter-vehicular distances, dangerous TTC (TTC < 6 seconds) is not frequent. Future research directions are also discussed along with the results.

  • 259.
    Aramrattana, Maytheewat
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES). The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Englund, Cristofer
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab). RISE Viktoria, Göteborg, Sweden.
    Jansson, Jonas
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Larsson, Tony
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Nåbo, Arne
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Safety Analysis of Cooperative Adaptive Cruise Control in Vehicle Cut-in Situations2017Ingår i: Proceedings of 2017 4th International Symposium on Future Active Safety Technology towards Zero-Traffic-Accidents (FAST-zero), Society of Automotive Engineers of Japan , 2017, artikel-id 20174621Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cooperative adaptive cruise control (CACC) is a cooperative intelligent transport systems (C-ITS) function, which especially when used in platooning applications, possess many expected benefits including efficient road space utilization and reduced fuel consumption. Cut-in manoeuvres in platoons can potentially reduce those benefits, and are not desired from a safety point of view. Unfortunately, in realistic traffic scenarios, cut-in manoeuvres can be expected, especially from non-connected vehicles. In this paper two different controllers for platooning are explored, aiming at maintaining the safety of the platoon while a vehicle is cutting in from the adjacent lane. A realistic scenario, where a human driver performs the cut-in manoeuvre is used to demonstrate the effectiveness of the controllers. Safety analysis of CACC controllers using time to collision (TTC) under such situation is presented. The analysis using TTC indicate that, although potential risks are always high in CACC applications such as platooning due to the small inter-vehicular distances, dangerous TTC (TTC < 6 seconds) is not frequent. Future research directions are also discussed along with the results.

  • 260.
    Aramrattana, Maytheewat
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Körsimulering och visualisering, SIM. Högskolan i Halmstad.
    Larsson, Tony
    Högskolan i Halmstad.
    Jansson, Jonas
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF.
    Nåbo, Arne
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Körsimulering och visualisering, SIM.
    Cooperative Driving Simulation2016Ingår i: Proceedings of the Driving Simulation Conference 2016, 2016, s. 123-132Konferensbidrag (Refereegranskat)
    Abstract [en]

    For a few decades, driving simulators have been supporting research and development of advanced driver assistance systems (ADAS). In the near future, connected vehicles are expected to be deployed. Driving simulators will need to support evaluation of cooperative driving applications within cooperative intelligent transportation systems (C-ITS) scenarios. C-ITS utilize vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication. Simulation of the inter vehicle communication is often not supported in driving simulators. On the other hand, previous efforts have been made to connect network simulators and traffic simulators, to perform C-ITS simulations. Nevertheless, interactions between actors in the system is an essential aspect of C-ITS. Driving simulators can provide the opportunity to study interactions and reactions of human drivers to the system. This paper present simulation of a C-ITS scenario using a combination of driving, network, and traffic simulators. The architecture of the solution and important challenges of the integration are presented. A scenario from Grand Cooperative Driving Challenge (GCDC) 2016 is implemented in the simulator as an example use case. Lastly, potential usages and future developments are discussed.

  • 261.
    Aramrattana, Maytheewat
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES). The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Larsson, Tony
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Jansson, Jonas
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Nåbo, Arne
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Cooperative Driving Simulation2016Ingår i: Proceedings of the Driving Simulation Conference 2016, 2016, s. 123-132Konferensbidrag (Refereegranskat)
    Abstract [en]

    For a few decades, driving simulators have been supporting research and development of advanced driver assistance systems (ADAS). In the near future, connected vehicles are expected to be deployed. Driving simulators will need to support evaluation of cooperative driving applications within cooperative intelligent transportation systems (C-ITS) scenarios. C-ITS utilize vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication. Simulation of the inter vehicle communication is often not supported in driving simulators. On the other hand, previous efforts have been made to connect network simulators and traffic simulators, to perform C-ITS simulations. Nevertheless, interactions between actors in the system is an essential aspect of C-ITS. Driving simulators can provide the opportunity to study interactions and reactions of human drivers to the system. This paper present simulation of a C-ITS scenario using a combination of driving, network, and traffic simulators. The architecture of the solution and important challenges of the integration are presented. A scenario from Grand Cooperative Driving Challenge (GCDC) 2016 is implemented in the simulator as an example use case. Lastly, potential usages and future developments are discussed.

  • 262.
    Aramrattana, Maytheewat
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES). The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Larsson, Tony
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Jansson, Jonas
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Nåbo, Arne
    The Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Extended Driving Simulator for Evaluation of Cooperative Intelligent Transport Systems2016Ingår i: SIGSIM-PADS '16: Proceedings of the 2016 annual ACM Conference on SIGSIM Principles of Advanced Discrete Simulation, New York: ACM Digital Library, 2016, s. 255-278Konferensbidrag (Refereegranskat)
    Abstract [en]

    Vehicles in cooperative intelligent transport systems (C-ITS) often need to interact with each other in order to achieve their goals, safe and efficient transport services. Since human drivers are still expected to be involved in C-ITS, driving simulators are appropriate tools for evaluation of the C-ITS functions. However, driving simulators often simplify the interactions or influences from the ego vehicle on the traffic. Moreover, they normally do not support vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication, which is the main enabler for C-ITS. Therefore, to increase the C-ITS evaluation capability, a solution on how to extend a driving simulator with traffic and network simulators to handle cooperative systems is presented as a result of this paper. Evaluation of the result using two use cases is presented. And, the observed limitations and challenges of the solution are reported and discussed. © 2016 ACM, Inc.

  • 263.
    Araujo Soto, Víctor Estuardo
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Performance evaluation of scalable and distributed iot platforms for smart regions2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    As the vision of the Internet of Things (IoT) becomes a reality, thousands of devices will beconnected to IoT platforms in smart cities and regions. These devices will actively send dataupdates to cloud-based platforms, as part of smart applications in domains like healthcare, trafficand pollution monitoring. Therefore, it is important to study the ability of modern IoT systemsto handle high rates of data updates coming from devices. In this work we evaluated the per-formance of components of the Internet of Things Services Enablement Architecture of theEuropean initiative FIWARE. We developed a testbed that is able to inject data updates usingMQTT and the CoAP-based Lightweight M2M protocols, simulating large scale IoT deploy-ments. Our extensive tests considered the vertical and horizontal scalability of the componentsof the platform. Our results found the limits of the components when handling the load, and thescaling strategies that should be targeted by implementers. We found that vertical scaling is notan effective strategy in comparison to the gains achieved by horizontally scaling the databaselayer. We reflect about the load testing methodology for IoT systems, the scalability needs ofdifferent layers and conclude with future challenges in this topic.

  • 264.
    Aravind, Meera
    et al.
    Mälardalens högskola.
    Wiklander, G.
    Uppsala University, Uppsala, Sweden.
    Palmheden, J.
    Scania AB, Södertälje, Sweden.
    Dobrin, Radu
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    An Event-Based Messaging Architecture for Vehicular Internet of Things (IoT) Platforms2017Ingår i: Communications in Computer and Information Science, vol. 778, Springer Verlag , 2017, s. 37-46Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet of Things (IoT) has revolutionized transportation systems by connecting vehicles consequently enabling their tracking, as well as monitoring of driver activities. Such an IoT platform requires a significant amount of data to be send from the on-board vehicle to the off-board servers, contributing to high network usage. The data can be send at regular intervals or in an event-based manner whenever relevant events occur. In interval-based approach, the data is send even if it is not relevant for reporting leading to a wastage of network resources, e.g., when the data does not change considerably compared to the previously sent value. In this paper, we investigate the possibility of using an event-based architecture to send data from the on-board system to the off-board system. The results show that our event-based architecture improves the accuracy of data available at the off-board system, by a careful selection of events. Moreover, we found that our event based architecture significantly decreases the frequency of sending messages, particularly during highway driving, leading to reduced average data transfer rates. Our results enable a customer to perform trade-offs between accuracy and data transfer rates. 

  • 265.
    Ardah, Khaled
    et al.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Ericsson Res, SE-16480 Stockholm, Sweden.
    Silva, Yuri C. B.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Freitas, Walter C., Jr.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Cavalcanti, Francisco R. P.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    A Unifying Design of Hybrid Beamforming Architectures Employing Phase Shifters or Switches2018Ingår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, nr 11, s. 11243-11247Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hybrid beamfiorming (BF) architectures employing phase shifters or switches reduce the number of required radio frequency chains and the power consumption of base stations that employ a large number of antennas. Due to the inherent tradeoff between the number of radio frequency chains, the complexity of the employed analog and digital BF algorithms and the achieved spectral and energy efficiency, designing hybrid BF architectures is a complex task. To deal with this ormplexity, we propose a unifying design that is applicable to architectures employing either phase shifters or switches. In our design, the analog part (!if the hybrid BF architecture maximizes the capacity of the equivalent channel, while the digital part is updated using the well-known block diagonalizat' approach. We then employ the proposed joint analog-digital beamforming algorithm on lour recently proposed hybrid architectures and compare their performance in terms of spectral and energy efficiency, and find that the proposed analog-digital BF algorithm outperforms previously proposed schemes. We also find that phase shifterbased architectures achieve high spectral efficiency, whereas switching-based architectures can boost energy efficiency with increasing number of base station antennas.

  • 266.
    Ardelius, John
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    On the Performance Analysis of Large Scale, Dynamic, Distributed and Parallel Systems.2013Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [sv]

    Att utvärdera prestanda hos storskaliga distribuerade system är en viktigoch icke-trivial uppgift. I och med utvecklingen av Internet och det faktum attapplikationer och system har fått global utsträckning, har det uppkommit ettökande behov av kvantifiering av tillförlitlighet och prestanda hos dessa system.Både som underlag för systemdesign men också för att skapa förståelseoch kunskap om fundamentala egenskaper hos distribuerade system.Tidigare forskning har i mångt och mycket fokuserat antingen på formaliserademodeller, där egenskaper kan härledas med hjälp av strikta matematiskametoder eller på mätningar av riktiga system. Målet med arbetet i dennaavhandling är att undersöka modeller på en abstraktionsnivå mellan dessa tvåytterligheter. Vi tillämpar en modell av distributerade system med inspirationfrån så kallade partikelmodeller från den teoretiska fysiken och modellererarapplikationsnoder som en samling interagerande pariklar var och en med sitteget interna tillstånd vars beteende beskrivs av det exekvernade programmeti fråga. Vi tillämpar denna modelerings- och utvärderingsmetod på fyra olikadistribuerade och parallella system.Det första systemet är den distribuerade hash tabellen (DHT) Chord i endynamisk miljö. Vi har valt att studera systemet under två scenarion. Förstutvärderar vi hur systemet beteer sig (med avseende på lookup latency) iett nätverk med finita kommunikationsfördröjningar. Vårt arbete visar atten generell fördröjning i nätet tillsammans med andra parametrar (som t.ex.tidsskala för felkorrektion och anslutningsprocess för noder) genererar fundamentaltskilda prestandamått. Vi verifierar vår analytiska model med simuleringar.I det andra scenariot undersöker vi betydelsen av NATs (networkadress translators) i nätverksmodellen. Förekomsten av dessa tar bort dentransitiva egenskapen hos nätverkstopologin och vi undersöker hur detta påverkarlookup-kostnad, datakonsistens och lastbalans. Denna analys är främst simuleringsbaserad.Även om dessa två studier fokuserar på en specifik DHT såkan de flesta resultat och metoden som sådan överföras på andra liknanderingbaserade DHTer med långa länkar och även andra geometrier.Den andra klassen av system som analyseras är ostrukturerade gossip protokolli form av den välkända Belman-Ford algoritmen. Algoritmen, GAP,skapar ett spännande träd över systemets noder. Problemställningen vi studerarär hur tillförlitlig denna struktur, med avseende på precisionen på aggregatvid rotnoden, är i ett dynamiskt nätverk. Samtliga analytiska resultatverifieras i simulator.Det tredje systemet vi undersöker är ett CDN (content distribution system)med en hierarkisk cache struktur i sitt distributionsnät. I den här modellenefterfrågas data från löven på cache-trädet. Antingen kan förfrågan servas avcacharna på de lägre nivåerna eller så skickas förfrågan vidare uppåt i trädet.Vi analyserar två fundamentala heuristiker, LRU och LFU. Vi jämför våraanalytiska resultat med tracedata från riktiga cachesystem.Till sist analyserar vi en heuristik för last distribution i TileraPro64 arkitekturen.Systemet har ett centralt delat minne och är därför att betrakta somparallellt. Vi skapar här en model för den dynamiska genereringen av lastsamt hur denna distribueras till de olika noderna på chipet. Vi studerar hur heuristiken skalar när antalet noder överstiger antalet på chipet (64) samtjämför prestanda hos olika heuristiker. Analysen är simuleringsbaserad.

  • 267.
    Ardelius, John
    et al.
    SICS.
    Grönvall, Björn
    SICS.
    Westberg, Lars
    Ericsson AB.
    Arvidsson, Åke
    Ericsson AB.
    On the effects of caching in access aggregation networks2012Ingår i: ICN 2012, Helsinki, Finland / [ed] Dirk Kutscher, Giacomo Morabito, Börje Ohlman, George C. Polyzos, Ignacio Solis och Lixia Zhang, Association for Computing Machinery (ACM), 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    All forecasts of Internet trac point at a substantial growth over the next few years. From a network operator perspective, efficient in-network caching of data is and will be a key component in trying to cope with and profit from this increasing demand. One problem, however, is to evaluate the performance of different caching policies as the number of available data items as well as the distribution networks grows very large.

    In this work, we develop an analytical model of an aggregation access network receiving a continuous flow of requests from external clients. We provide exact analytical solutions for cache hit rates, data availability and more. This enables us to provide guidelines and rules of thumb for operators and Information-Centric Network designers.

    Finally, we apply our analytical results to a real VoD trace from a network operator and show that substantial bandwidth savings can be expected when using in-network caching in a realistic setting.

  • 268. Argunsah, Ali Özgur
    et al.
    Çürüklü, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Cetin, Mujdat
    Detection of Eye Blinks from EEG using Hidden Markov Models2009Konferensbidrag (Refereegranskat)
  • 269.
    Arias Ramos, Ceferino
    Högskolan i Skövde, Institutionen för teknik och samhälle.
    Programming and Image Processing in a Compact Production Cell2012Självständigt arbete på grundnivå (kandidatexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In recent years, control system in the automation industries has become more and more useful, covering a wide range of fields, for example, industrial instrumentation, control and monitoring systems. Vision systems are used nowadays to improve products quality control, saving costs, time, and obtaining a better accuracy than a human operator in the manufacturing process of companies. Combining a vision system with a suitable automated system allow companies to cover a wide range of products and rapid production. All these factors are considered in this project.

    The aim of this project is to upgrade the functionality of a Nokia-Cell, which was used in a quality control process for the back shells of Nokia cell phones. The project includes design, upgrade and implementation of a new system in order to make the cell work properly. The Nokia-Cell is composed of the following basic modules: vision and image recognition system, automation system devices (PC and PLC, robot), and other mechatronics devices. The new system will consist of a new camera, due to the poor connectivity and quality of the old camera. For the same reason, a new PC will replace two older ones for communication and vision recognition. The new system will also include a new PLC of Beckhoff to replace the aging one of Omron so as to facilitate the connections using the same language. In addition, IEC-61499 Function Blocks standard is adopted for programming the Nokia-Cell.

    It is expected that the results of this project will contribute to both research and education in the future. In addition, it would be correctly to apply the results to industries in vision-based quality control systems.

  • 270. Arlebrink, Ludvig
    et al.
    Linde, Fredrik
    Image Quality-Driven Level of Detail Selection on a Triangle Budget2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Background. Level of detail is an optimization technique used by several modern games. The level of detail systems uses simplified triangular meshes to determine the optimal combinations of 3D-models to use in order to meet a user-defined criterion for achieving fast performance. Prior work has also pre-computed level of detail settings to only apply the most optimal settings for any given view in a 3D scene.

    Objectives. The aim of this thesis is to determine the difference in image quality between a custom level of detail pre-preprocessing approach proposed in this paper, and the level of detail system built in the game engine Unity. This is investigated by implementing a framework in Unity for the proposed level of detail pre-preprocessing approach in this paper and designing representative test scenes to collect all data samples. Once the data is collected, the image quality produced by the proposed level of detail pre-preprocessing approach is compared to Unity's existing level of detail approach using perceptual-based metrics.

    Methods. The method used is an experiment. Unity's method was chosen because of the popularity of the engine, and it was decided to implement the proposed level of detail pre-preprocessing approach also in Unity to have the most fair comparison with Unity's implementation. The two approaches will only differ in how the level of detail is selected, the rest of the rendering pipeline will be exactly the same.

    Results. The pre-preprocessing time ranged between 13 to 30 hours. The results showed only a small difference in image quality between the two approaches, Unity's built-in system provides a better overall image quality in two out of three test scenes.

    Conclusions. Due to the pre-processing time and no overall improvement, it was concluded that the proposed level of detail pre-preprocessing approach is not feasible.

  • 271.
    Arman, Ala
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    Al-Shishtawy, Ahmad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    Vlassov, Vladimir
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Programvaruteknik och Datorsystem, SCS.
    Elasticity controller for Cloud-based key-value stores2012Ingår i: Parallel and Distributed Systems (ICPADS), 2012 IEEE 18th International Conference on, IEEE , 2012, s. 268-275Konferensbidrag (Refereegranskat)
    Abstract [en]

    Clouds provide an illusion of an infinite amount of resources and enable elastic services and applications that are capable to scale up and down (grow and shrink by requesting and releasing resources) in response to changes in its environment, workload, and Quality of Service (QoS) requirements. Elasticity allows to achieve required QoS at a minimal cost in a Cloud environment with its pay-as-you-go pricing model. In this paper, we present our experience in designing a feedback elastically controller for a key-value store. The goal of our research is to investigate the feasibility of the control theoretic approach to the automation of elasticity of Cloud-based key-value stores. We describe design steps necessary to build a feedback controller for a real system, namely Voldemort, which we use as a case study in this work. The design steps include defining touchpoints (sensors and actuators), system identification, and controller design. We have designed, developed, and implemented a prototype of the feedback elasticity controller for Voldemort. Our initial evaluation results show the feasibility of using feedback control to automate elasticity of distributed keyvalue stores.

  • 272. Armengaud, Eric
    et al.
    Biehl, Matthias
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Bourrouilh, Quentin
    Breunig, Michael
    Farfeleder, Stefan
    Hein, Christian
    Oertel, Markus
    Wallner, Alfred
    Zoier, Markus
    Integrated tool chain for improving traceability during the development of automotive systems2012Ingår i: ERTS2 2012 | Embedded Real Time Software and Systems, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Tool integration is a key factor for improving development efficiency and product quality during the development of safety-relevant embedded systems. We present in this work a demonstrator based on the most recent outcomes of the CESAR project. The proposed integrated tool-chain aims at better linking development activities together, thus improving traceability during requirements engineering, system design, safety analysis and V&V activities using a model-based development approach. We analyze the proposed tool-chain from three different points of view: (1) tool integrator, (2) technology provider, and (3) end-user. These different points of view enable the description of the different technologies used at the different levels and the analysis of the benefits for the end-user.

  • 273.
    Aronis, Stavros
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Sagonas, Konstantinos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Lystig Fritchie, Scott
    VMware, Cambridge, MA, USA.
    Testing And Verifying Chain Repair Methods For CORFU Using Stateless Model Checking2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Corfu is a distributed shared log that is designed to be scalable and reliable in the presence of failures and asynchrony. Internally, Corfu is fully replicated for fault tolerance, without sharding data or sacrificing strong consistency. In this case study, we present the modeling approaches we followed to test and verify, using Concuerror, the correctness of repair methods for the Chain Replication protocol suitable for Corfu. In the first two methods we tried, Concuerror located bugs quite fast. In contrast, the tool did not manage to find bugs in the third method, but the time this took also motivated an improvement in the tool that reduces the number of traces explored. Besides more details about all the above, we present experiences and lessons learned from applying stateless model checking for verifying complex protocols suitable for distributed programming.

  • 274.
    Aronsson, John
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi.
    Bolmér, Percy
    Högskolan i Halmstad, Akademin för informationsteknologi.
    Hur forensiska verktyg påverkar integriteten på mobiltelefoner2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Användandet av mobiltelefoner och andra mobila enheter är stort i samhället vilket gör att de förekommer allt oftare vid brott och brottsutredningar. Information i dessa enheter måste kunna utvinnas och integriteten på det utvinna materialet säkerställas. Syftet med detta arbete är att undersöker om de forensiska verktygen Xry och Encase påverkar materialet vid utvinning från mobiltelefoner. För att ta reda på detta har en litteraturstudie, en intervju och två experiment utförts. Resultatet från experimenten visade på att det fanns filer vars innehåll ändrades mellan utvinningar. En analys av resultatet visade att det var systemet själv samt processer som skedde innan utvinningen som förändrat innehållet. Slutsatsen blev att verktygen inte påverkar materialet under utvinningsprocessen

  • 275.
    Artho, Cyrille
    et al.
    KTH.
    Ölveczky, P.C.
    Preface2017Ingår i: 5th International Workshop on Formal Techniques for Safety-Critical Systems, FTSCS 2016, Springer Verlag , 2017Konferensbidrag (Refereegranskat)
  • 276.
    Arunachalam, Ajay
    et al.
    Department of Computer Science, Graduate School of Applied Statistics, National Institute of Development Administration, Thailand.
    Sornil, Ohm
    Department of Computer Science, Graduate School of Applied Statistics, National Institute of Development Administration, Thailand.
    A broadcast based random query gossip algorithm for resource search in non-DHT mobile Peer-to-Peer networks2017Ingår i: Diànnǎo xuékān, ISSN 1991-1599, Vol. 28, nr 1, s. 209-223Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a resource discovery scheme for decentralized non-DHT Mobile Peer-to-Peer (MP2P) networks. In a mobile environment, the energy of mobile device is very critical. The aim of the proposed technique is to reduce the network overhead, lower battery power consumption and minimize query delay while improving the chance to resolve the query at every successive stage. Peer-to-Peer applications have gained a lot of attention in past years due to its decentralized nature. Resource searching algorithms are one of the major focuses of P2P network. Mobile Ad hoc Network (MANET) with its changing topology further poses additional challenges and thus increasing the search effort. Methods like flooding, random walk and probabilistic forwarding techniques are good candidates to run over such dynamic network. In this work, we study the flooding, random walk and gossip based resource discovery protocols on a P2P Mobile Ad hoc Network. We observed that the classic gossip algorithm does not work well under MANET as in the case of a wired network. We focus to improve the algorithm to suit and work better under such dynamic network scenario. The proposed system presents a light weight resource discovery design to suit the mobility requirement of ad hoc networks to optimize the search performance while at the same time minimize the extra usage of mobile and network resources. For quick and energy efficient search scheme, we explore a novel addressed jumping approach. Our algorithm is entirely distributed, and hence will scale well even to the growing size of the network. The efficiency of our proposed algorithm is validated through extensive NS-2 simulations. The results show that our proposed scheme gives better performance than the widely used techniques. We also validate through statistical hypothesis testing of simulation data.

  • 277.
    Arunachalam, Ajay
    et al.
    Department of Computer Science, School of Applied Statistics, National Institute of Development Administration, Bangkok, Thailand.
    Sornil, Ohm
    Department of Computer Science, School of Applied Statistics, National Institute of Development Administration, Bangkok, Thailand.
    Reducing Routing Overhead in random walk protocol under MP2P Network2016Ingår i: International Journal of Electrical and Computer Engineering, ISSN 2088-8708, Vol. 6, nr 6, s. 3121-3130Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Due to network dynamics in self-organizing networks the resource discovery effort increases. To discover objects in unstructured peer-to-peer network, peers rely on traditional methods like flooding, random walk and probabilistic forwarding methods. With inadequate knowledge of paths, the peers have to flood the query message which creates incredible network traffic and overhead. Many of the previous works based on random walk were done in wired network. In this context random walk was better than flooding. But under MANETs random walk approach behaved differently increasing the overhead, due to frequent link failures incurred by mobility. Decentralized applications based on peer-to-peer computing are best candidates to run over such dynamic network. Issues of P2P service discovery in wired networks have been well addressed in several earlier works. This article evaluates the performance of random walk based resource discovery protocol over P2P Mobile Adhoc Network (MP2P) and suggests an improved scheme to suit MANET. Our version reduces the network overhead, lowers the battery power consumption, minimizes the query delay while providing equally good success rate. The protocol is validated through extensive NS-2 simulations. It is clear from the results that our proposed scheme is an alternative to the existing ones for such highly dynamic mobile network scenario.

  • 278.
    Arvidsson, Simon
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Datateknik och informatik.
    Gullstrand, Marcus
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Datateknik och informatik.
    Classifying natural forests using LiDAR data2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In forestry, natural forests are forest areas with high biodiversity, in need of preservation. The current mapping of natural forests is a tedious task that requires manual labor that could possibly be automated.

    In this paper we explore the main features used by a random forest algorithm to classify natural forest and managed forest in northern Sweden. The goal was to create a model with a substantial strength of agreement, meaning a Kappa value of 0.61 or higher, placing the model in the same range as models produced in previous research.

    We used raster data gathered from airborne LiDAR, combined with labeled sample areas, both supplied by the Swedish Forest Agency. Two experiments were performed with different features. Experiment 1 used features extracted using methods inspired from previous research while Experiment 2 further added upon those features. From the total number of used sample areas (n=2882), 70% was used to train the models and 30% was used for evaluation.

    The result was a Kappa value of 0.26 for Experiment 1 and 0.32 for Experiment 2. Features shown to be prominent are features derived from canopy height, where the supplied data also had the highest resolution. Percentiles, kurtosis and canopy crown areas derived from the canopy height were shown to be the most important for classification. The results fell short of our goal, possibly indicating a range of flaws in the data used. The size of the sample areas and resolution of raster data are likely important factors when extracting features, playing a large role in the produced model’s performance.

  • 279.
    Arvidsson, Åke
    et al.
    Ericsson AB.
    Du, Manxing
    Acreo.
    Aurelius, Andreas
    Acreo.
    Kihl, Maria
    Lunds universitet.
    Analysis of user demand patterns and locality for YouTube traffic2013Ingår i: 25th International Teletraffic Congress / [ed] Zhisheng Niu. Kurt Tutschku. Zhanhong Xin och Moshe Zukerman, IEEE Communications Society, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Video content, of which YouTube is a major part, constitutes a large share of residential Internet traffic. In this paper, we analyse the user demand patterns for YouTube in two metropolitan access networks with more than 1 million requestsover three consecutive weeks in the first network and more than 600,000 requests over four consecutive weeks in the second network.

    In particular we examine the existence of “local interest communities”, i.e. the extent to which users living closer to each other tend to request the same content to a higher degree, and it is found that this applies to (i) the two networks themselves; (ii) regions within these networks (iii) households with regions and (iv) terminals within households. We also find that different types of access devices (PCs and handhelds) tend to form similar interest communities.

    It is also found that repeats are (i) “self-generating” in the sense that the more times a clip has been played, the higher the probability of playing it again, (ii) “long-lasting” in the sense that repeats can occur even after several days and (iii) “semi regular”in the sense that replays have a noticeable tendency tooccur with relatively constant intervals.

    The implications of these findings are that the benefits from large groups of users in terms of caching gain may be exaggerated, since users are different depending on where they live and what equipment they use, and that high gains can be achieved in relatively small groups or even for individual users thanks totheir relatively predictable behaviour.

  • 280.
    Arvidsson, Åke
    et al.
    Högskolan Kristianstad, Sektionen för hälsa och samhälle, Avdelningen för Design och datavetenskap. Ericsson AB.
    Rydén, Tobias
    Uppsala University.
    Load transients in pooled cellular core network nodes2015Ingår i: Performance evaluation (Print), ISSN 0166-5316, E-ISSN 1872-745X, Vol. 90, s. 18-35Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The coverage areas of cellular networks are logically subdivided into service areas. Each service area has a local anchor node which “hides” the mobility inside the area and the entire network has a global anchor node which “hides” the mobility between areas.

    The concept of unique local anchor nodes per service area was invented to simplify routing but has been found to complicate expansion. The rapidly growing demand for cellular access has therefore prompted for alternative solutions with pools of local anchor nodes per service area. Such pools are now deployed by several operators all over the world.

    Users in pooled service areas are mapped to specific pool members according to a load distribution policy, but the mapping can change as a result of node failures or operator interventions. Such changes take a certain time to implement and cause additional load on the anchor nodes. We study these processes in detail and derive closed form expressions which allow operators to control the trade-off between rapid changes and acceptable loads.

    Finally we show that the key assumptions of our model are in agreement with measured data and demonstrate how the model can be applied to investigate the effects of different network settings (timers) under different user behaviour (traffic and mobility).

    Contrary to current solutions to this problem, which typically are slow and/or inaccurate, our results enable fast and accurate analysis of different scenarios thereby enabling operators to maximise utilisation of the existing investments and at the same time avoid potentially dangerous situations of overload.

  • 281.
    Arvidsson, Åke
    et al.
    Högskolan Kristianstad, Fakulteten för naturvetenskap, Avdelningen för datavetenskap.
    Westberg, Lars
    Kungliga tekniska högskolan.
    Fast transport for edge computing in 5G networks2018Ingår i: Proceedings of 2018 26th International Conference on Software, Telecommunications and Computer Networks (SoftCOM) / [ed] Dinko Begušić, Nikola Rožić, Joško Radić, and Matko Šarić, New York: IEEE Communications Society, 2018, s. 41-45Konferensbidrag (Refereegranskat)
    Abstract [en]

    We consider TCP performance for cloud servicesin 5G cellular networks and show that edge clouds offer the highest throughput, but that further improvements still arepossible. To this end we devise a concept where edge clouds connected directly to the radio access network can increase their transmission rates by relying on the built in re-transmissions (through quality of service features) and on the built in userfairness (through per-user buffers and scheduler policies). We use numerical examples from measurements in real networks to demonstrate that the concept is efficient and significantly improves the effective throughput beyond what placement alone can do, and we also outline possible further improvements.

  • 282.
    Arvidsson, Åke
    et al.
    Högskolan Kristianstad, Fakulteten för naturvetenskap, Avdelningen för datavetenskap.
    Westberg, Lars
    Kungliga Tekniska Högskolan.
    Transport bottlenecks of edge computing in 5G networks2019Ingår i: Journal of Communication Software and Systems, ISSN 1845-6421, E-ISSN 1846-6079, Vol. 15, nr 1, s. 59-65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider bottlenecks of TCP throughput in scenarios with edge clouds and 5G cellular networks. By numerical examples from measurements in real networks, we show that edge clouds indeed improve throughput but that several, nonnegligible bottlenecks remain. We therefore devise a concept where edge clouds connected directly to the radio access networkcan increase their transmission rates by relying on built in retransmissions (through quality of service features) and on the built in user fairness (through per-user buffers and scheduler policies). We then return to the numerical examples and show that our solution provides substantial gains and we concludeby identifying and discussing the remaining bottlenecks and the potential of an improved protocol.

  • 283.
    Arvidsson, Åke
    et al.
    Ericsson AB.
    Zhang, Ying
    Ericsson AB.
    Detecting user dissatisfaction and understanding the underlying reasons2013Ingår i: ACM SIGMETRICS / International conference on measurement and modeling of computer systems, SIGMETRICS '13, Pittsburgh, PA, USA, June 17-21, 2013 / [ed] John Douceur och Jun Xu, Association for Computing Machinery (ACM), 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Quantifying quality of experience for network applications is challenging as it is a subjective metric with multiple dimensions such as user expectation, satisfaction, and overall experience. Today, despite various techniques to support differentiated Quality of Service (QoS), the operators still lack of automated methods to translate QoS to QoE, especially for general web applications.

    In this work, we take the approach of identifying unsatisfactory performance by searching for user initiated early terminations of web transactions from passive monitoring. However, user early abortions can be caused by other factors such as loss of interests. Therefore, naively using them to represent user dissatisfaction will result in large false positives. In this paper, we propose a systematic method for inferring user dissatisfaction from the set of early abortion behaviors observed from identifying the traffic traces. We conduct a comprehensive analysis on the user acceptance of throughput and response time, and compare them with the traditional MOS metric. Then we present the characteristics of early cancelation from dimensions like the types of URLs and objects. We evaluate our approach on four data sets collected in both wireline network and a wireless cellular network.

  • 284.
    Arvidsson, Åke
    et al.
    Ericsson AB.
    Zhang, Ying
    Ericsson AB.
    Neda, Beheshti
    Ericsson AB.
    Detecting user dissatisfaction from passive monitoring2013Ingår i: Proceedings of Eurocon 2013, International Conference on computer as a tool, Zagreb, Croatia, July 1-4, 2013, IEEE Communications Society, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In an increasingly competitive environment it is more important than ever for operators to keep their end users satisfied. User satisfaction is often characterised in terms of Quality of Experience (QoE), a subjective metric with multiple dimensions such as expectations, content, terminal, environment, cost and performance. QoE is typically quantified as MOS, mean opinion score, which is obtained by averaging the ranks of a number of voluntary users for controlled combinations content/terminals/performance etc. While this approach has many advantages, there are also a number of difficulties such as representativeness (the number of users as well as the number of objects and devices all have to be kept small); validity (the results may be biased by the situation, the setting, the renumeration and so on); and applicability (it is not clear how different numbers map to notions such as “acceptable” or “unacceptable” and operators alone cannot do very much about factors such as content).

    We thus investigate the possibilities of detecting user opinions in the above, simplified, terms and from the network itself; with actual expectations, content, terminals, environments, costs and performance for virtually all users all the time. To this end we revisit the earlier suggestion that user opinions be reflected in their behaviour such that poor performance may result in interrupted requests. These works have, however, considered single flows hence we extend that idea to web pages which are groups of flows. In this paper we present our methods to group flows, interpret users, and characterise performance and we make a first assessment of the correlations between web page interruptions and network performance characteristics.

  • 285.
    Aryefyev, Maksym
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    NAT traversal techniques for MediaSense open source platform2013Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis project concerns NAT traversal techniques and their application to P2P networking with regard to MediaSense platform. Since MediaSense open source platform, developed by Mid Sweden University, utilizes the benefits of P2P networking, it also suffers from the drawbacks provided by NAT. The issue of NAT traversal is not trivial due to the fact that the behavior of NAT devices is not standardized and vendors are free to provide their own implementations. The common knowledge is, that at least four main types of NATs exist, differing in the filtering and mapping algorithms employed. NAT traversal techniques vary accordingly. No single technique can handle all the cases. Most of the techniques can handle up to three main types of NAT. The last type is usually used in large corporate networks and is called the Symmetric NAT. The most viable, and basically the only available technique for its traversal, is data relaying. This thesis builds a NAT traversal module for the MediaSense platform. The main purpose of this module is to provide seamless NAT traversal capabilities to the platform. The module does this in several steps: UPnP enabled device discovery, NAT type determination and data relaying via the proxy. Firstly the module attempts to discover the presence of a UPnP enabled Internet Gateway Device on the network. If such a device is present on the network, a port mapping can be created, making the node located behind NAT accessible from the public Internet. If a UPnP enabled device was not found, the module will try to determine the type of NAT used. Based on the type of NAT used, the module can transit to either the proxy mode or request assistance of the STUN server to keep the created mapping alive. The resulting chapters provide the reader with the output produced by each step, conclusions the author has made while working on this project and some general ideas on future work within the subject.

  • 286.
    Asada, Akira
    et al.
    Osaka Inst Technol, Fac Informat Sci & Technol, Osaka, Japan.
    Hayashi, Masaki
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Institutionen för speldesign.
    Hirayama, Makoto J.
    Osaka Inst Technol, Fac Informat Sci & Technol, Osaka, Japan.
    TV production tool to make art programmes based on a simple scenario2019Ingår i: INTERNATIONAL WORKSHOP ON ADVANCED IMAGE TECHNOLOGY (IWAIT) 2019 / [ed] Kemao, Q Hayase, K Lau, PY Lie, WN Lee, YL Srisuk, S Yu, L, SPIE-INT SOC OPTICAL ENGINEERING , 2019, artikel-id 1104921Konferensbidrag (Refereegranskat)
    Abstract [en]

    We have been studying and developing the real-time Computer Graphics (CG) based virtual museum where a user can walk through to appreciate artworks digitized in high-resolution. Our virtual museum also has a function to automatically create TV program-like CG animations using 3D CG models in the virtual space as it is so that the user can learn about individual works by watching the art shows. The CG animation is produced with TVML (TV program Making Language) engine implemented on the virtual museum. However, the current problem is that it requires a lot of work for a developer to write the complicated TVML scripts manually Therefore, this time we have developed a special tool to help the developer to prepare the TVML scripts easily. With this tool, the developer can produce the TVML-based art program simply by writing out a simple scenario on an ordinary text editor. In order to design this tool, TV art programs actually broadcasted are analyzed to determine the syntax of the simple scenario. Based on the analysis, we have developed the tool with TVML engine working on the Unity game Engine. We have also used this tool to imitate the broadcasted TV program to validate its usability.

  • 287. Asan, Noor Badariah
    et al.
    Hassan, Emadeldeen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Perez, Mauricio David
    Shah, Syaiful Redzwan Mohd
    Velander, Jacob
    Blokhuis, Taco J.
    Voigt, Thiemo
    Augustine, Robin
    Assessment of Blood Vessel Effect on Fat-Intrabody Communication Using Numerical and Ex-Vivo Models at 2.45 GHZ2019Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 7, s. 89886-89900Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The potential offered by the intra-body communication (IBC) over the past few years has resulted in a spike of interest for the topic, specifically for medical applications. Fat-IBC is subsequently a novel alternative technique that utilizes fat tissue as a communication channel. This work aimed to identify such transmission medium and its performance in varying blood-vessel systems at 2.45 GHz, particularly in the context of the IBC and medical applications. It incorporated three-dimensional (3D) electromagnetic simulations and laboratory investigations that implemented models of blood vessels of varying orientations, sizes, and positions. Such investigations were undertaken by using ex-vivo porcine tissues and three blood-vessel system configurations. These configurations represent extreme cases of real-life scenarios that sufficiently elucidated their principal influence on the transmission. The blood-vessel models consisted of ex-vivo muscle tissues and copper rods. The results showed that the blood vessels crossing the channel vertically contributed to 5.1 dB and 17.1 dB signal losses for muscle and copper rods, respectively, which is the worst-case scenario in the context of fat-channel with perturbance. In contrast, blood vessels aligned-longitudinally in the channel have less effect and yielded 4.5 dB and 4.2 dB signal losses for muscle and copper rods, respectively. Meanwhile, the blood vessels crossing the channel horizontally displayed 3.4 dB and 1.9 dB signal losses for muscle and copper rods, respectively, which were the smallest losses among the configurations. The laboratory investigations were in agreement with the simulations. Thus, this work substantiated the fat-IBC signal transmission variability in the context of varying blood vessel configurations.

  • 288.
    Asghar, Adeel
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Pfeiffer, Andreas
    DLR Institute of System Dynamic and Control, Wessling, Tyskland.
    Palanisamy, Arunkumar
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Mengist, Alachew
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Sjölund, Martin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Pop, Adrian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Automatic Regression Testing of Simulation Models and Concept for Simulation of Connected FMUs in PySimulator2015Ingår i: Proceedings of the 11th International Modelica Conference: Versailles, France, September 21-23, 2015 / [ed] Peter Fritzson, Hilding Elmqvist, Linköping, 2015, s. 671-679Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Modelica and FMI tool ecosystem is growing each year with new tools and methods becoming available. The open Modelica standard promises portability but it is important to ensure that a certain model behaves the same in different Modelica tools or in a different version of the same tool. It is also very important (for model evolution) to check that a new version of the same model produces comparable results. Finally, it is desirable to verify that a model exported in FMU form from a Modelica tool gives exactly the same results as the original model. This paper presents a framework for automatic regression testing as part of PySimulator which provides an efficient and concise way of testing if a model or a range of models behaves in the same way in several tools or versions of a tool by checking that the results produced are essentially identical. The FMI standard has been adopted by many tool vendors and is growing in popularity each year. This paper proposes a concept for building and simulating a system made from connected FMUs generated by different tools. The FMUs for Co-Simulation can be connected together using a GUI. The system model built graphically in this way can be saved for later use or simulated directly inside PySimulator. Active development is going on to support simulation of connected FMUs for Model Exchange.

  • 289.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. University of Porto, Porto, Portugal .
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    MTU Configuration for Real-Time Switched Ethernet Networks2016Ingår i: Journal of systems architecture, ISSN 1383-7621, E-ISSN 1873-6165, Vol. 70, s. 15-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we show that in real-time switched Ethernet networks reducing the Maximum Transmission Unit (MTU) size may cause an increase or decrease in the response time of messages. This contradicting behavior arises an optimization problem for configuring the MTU size. We formulate the optimization problem in the context of the multi-hop HaRTES architecture, which is a hard real-time Ethernet protocol. As part of the solution, we propose a search-based algorithm to achieve optimum solutions. We modify the algorithm by presenting two techniques to reduce the search space. Then, we propose a heuristic algorithm with a pseudo-polynomial time complexity based on the search-based algorithm. We perform several experiments, and we show that the proposed heuristic results in an improvement regarding messages response times, compared with configuring the MTU to the maximum or minimum values. Moreover, we show in small network configurations that the heuristic performs as good as the search-based algorithm in many cases.

  • 290. Ashjaei, Mohammad
    et al.
    Clegg, Kester
    Corneo, Lorenzo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Hawkins, Richard
    Jaradat, Omar
    Gulisano, Vincenzo Massimiliano
    Nikolakopoulos, Yiannis
    Service Level Agreements for Safe and Configurable Production Environments2018Ingår i: 2018 IEEE 23rd International Conference on Emerging Technologies and Factory Automation (ETFA), IEEE, 2018, s. 1252-1255Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper focuses on Service Level Agreements (SLAs) for industrial applications that aim to port some of the control functionalities to the cloud. In such applications, industrial requirements should be reflected in SLAs. In this paper, we present an approach to integrate safety-related aspects of an industrial application to SLAs. We also present the approach in a use case. This is an initial attempt to enrich SLAs for industrial settings to consider safety aspects, which has not been investigated thoroughly before.

  • 291.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Du, Yong
    Almeida, L.
    University of Porto, Porto, Portugal .
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Dynamic reconfiguration in HaRTES switched ethernet networks2016Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS, 2016, artikel-id Article number 7496510Konferensbidrag (Refereegranskat)
    Abstract [en]

    The ability of reconfiguring a system during runtime is essential for dynamic real-time applications in which resource usage is traded online for quality of service. The HaRTES switch, which is a modified Ethernet switch, holds this ability for the network resource, and at the same time it provides hard real-time support for both periodic and sporadic traffic. Although the HaRTES switch technologically caters this ability, a protocol to actually perform the dynamic reconfiguration is missing in multi-hop HaRTES networks. In this paper we introduce such a protocol that is compatible with the traffic scheduling method used in the architecture. We prove the correctness of the protocol using a model checking technique. Moreover, we conduct a set of simulation experiments to show the performance of the protocol and we also show that the reconfiguration process is terminated within a bounded time. 

  • 292.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Khalilzad, Nima
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. IS (Embedded Systems).
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Sander, Ingo
    Royal Institute of Technology, Sweden.
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Designing End-to-end Resource Reservations in Predictable Distributed Embedded Systems2017Ingår i: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 53, nr 6, s. 916-956Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Contemporary distributed embedded systems in many domains have become highly complex due to ever-increasing demand on advanced computer controlled functionality. The resource reservation techniques can be effective in lowering the software complexity, ensuring predictability and allowing flexibility during the development and execution of these systems. This paper proposes a novel end-to-end resource reservation model for distributed embedded systems. In order to support the development of predictable systems using the proposed model, the paper provides a method to design resource reservations and an end-to-end timing analysis. The reservation design can be subjected to different optimization criteria with respect to runtime footprint, overhead or performance. The paper also presents and evaluates a case study to show the usability of the proposed model, reservation design method and end-to-end timing analysis. 

  • 293. Ashjaei, Mohammad
    et al.
    Moghaddami Khalilzad, Nima
    KTH.
    Mubeen, Saad
    Behnam, Moris
    Sander, Ingo
    Almeida, Luis
    Nolte, Thomas
    Designing end-to-end resource reservations in predictable distributed embedded systems2017Ingår i: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 53, nr 6, s. 916-956Artikel i tidskrift (Refereegranskat)
  • 294.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    End-to-end Resource Reservations in Distributed Embedded Systems2016Ingår i: Proceedings - 2016 IEEE 22nd International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2016, 2016, s. 1-11, artikel-id 7579921Konferensbidrag (Refereegranskat)
    Abstract [en]

    The resource reservation techniques provide effective means to lower the software complexity, ensure predictability and allow flexibility during the development and execution of complex distributed embedded systems. In this paper we propose a new end-to-end resource reservation model for distributed embedded systems. The model is comprehensive in such a way that it supports end-to-end resource reservations on distributed transactions with various activation patterns that are commonly used in industrial control systems. The model allows resource reservations on processors and real-time network protocols. We also present timing analysis for the distributed embedded systems that are developed using the proposed model. The timing analysis computes the end-to-end response times as well as delays such as data age and reaction delays. The presented analysis also supports real-time networks that can autonomously initiate transmissions. Such networks are not supported by the existing analyses. We also include a case study to show the usability of the model and end-to-end timing analysis with resource reservations.

  • 295.
    Ashjaei, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Patti, Gaetano
    University of Catania, Italy.
    Behnam, Moris
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Alderisi, Giuliana
    University of Catania, Italy.
    Lo Bello, Lucia
    University of Catania, Italy.
    Schedulability Analysis of Ethernet Audio Video Bridging Networks with Scheduled Traffic Support2017Ingår i: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 53, nr 4, s. 526-577Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The IEEE Audio Video Bridging (AVB) technology is nowadays under consideration in several automation domains, such as, automotive, avionics, and industrial communications. AVB offers several benefits, such as open specifications, the existence of multiple providers of electronic components, and the real-time support, as AVB provides bounded latency to real-time traffic classes. In addition to the above mentioned properties, in the automotive domain, comparing with the existing in-vehicle networks, AVB offers significant advantages in terms of high bandwidth, significant reduction of cabling costs, thickness and weight, while meeting the challenging EMC/EMI requirements. Recently, an improvement of the AVB protocol, called the AVB ST, was proposed in the literature, which allows for supporting scheduled traffic, i.e., a class of time-sensitive traffic that requires time-driven transmission and low latency. In this paper, we present a schedulability analysis for the real-time traffic crossing through the AVB ST network. In addition, we formally prove that, if the bandwidth in the network is allocated according to the AVB standard, the schedulability test based on response time analysis will fail for most cases even if, in reality, these cases are schedulable. In order to provide guarantees based on analysis test a bandwidth over-reservation is required. In this paper, we propose a solution to obtain a minimized bandwidth over-reservation. To the best of our knowledge, this is the first attempt to formally spot the limitation and to propose a solution for overcoming it. The proposed analysis is applied to both the AVB standard and the AVB ST. The analysis results are compared with the results of several simulative assessments, obtained using OMNeT++, on both automotive and industrial case studies. The comparison between the results of the analysis and the simulation ones shows the effectiveness of the analysis proposed in this work.

  • 296.
    Ashjaei, Seyed Mohammad Hossein
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Clegg, Kester
    University of York, UK.
    Corneo, Lorenzo
    Uppsala University, Sweden.
    Hawkins, Richard
    University of York, UK.
    Jaradat, Omar
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Gulisano, Vincenzo
    Chalmers University of Technology, Göteborg, Sweden.
    Nikolakopoulos, Yiannis
    Chalmers University of Technology, Göteborg, Sweden.
    Service Level Agreements for Safe and Configurable Production Environments2018Ingår i: International Conference on Emerging Technologies and Factory Automation - Work in Progress Session ETFA-WiP'18, 2018, s. 1252-1255, artikel-id 8502568Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper focuses on Service Level Agreements (SLAs) for industrial applications that aim to port some of the control functionalities to the cloud. In such applications, industrial requirements should be reflected in SLAs. In this paper, we present an approach to integrate safety-related aspects of an industrial application to SLAs. We also present the approach in a use case. This is an initial attempt to enrich SLAs for industrial settings to consider safety aspects, which has not been investigated thoroughly before.

  • 297.
    Ashjaei, Seyed Mohammad Hossein
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Khalilzad, Nima
    Qamcom Research and Technology, Stockholm, Sweden.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Modeling, Designing and Analyzing Resource Reservations in Distributed Embedded Systems2018Ingår i: Real-Time Modelling and Processing for Communication Systems / [ed] Springer, Springer , 2018, s. 203-256Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 298.
    Ashjaei, Seyed Mohammad Hossein
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Lundbäck, John
    Arcticus Systems AB, Sweden.
    Gålnander, Mattias
    Arcticus Systems AB, Sweden.
    Lundbäck, Kurt-Lennart
    Arcticus Systems AB, Sweden.
    Nolte, Thomas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Modeling and Timing Analysis of Vehicle Functions Distributed over Switched Ethernet2017Ingår i: IECON 2017 - 43RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY, 2017, s. 8419-8424Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper proposes an approach to model switched Ethernet communication within a model- and component-based software development framework for vehicular distributed embedded systems. The paper also presents a method to extract the network timing model from the systems that use switched Ethernet networks. In order to provide a proof of concept, an existing industrial component model and its tool suite, namely RCM and Rubus-ICE respectively, are extended by implementing the modeling technique, the timing model extraction method and response-time analysis of the Ethernet AVB protocol. The extensions to RCM are backward compatible with the modeling and end-to-end timing analysis of traditional in-vehicle networks and legacy (previously developed) vehicular distributed embedded systems. Furthermore, the paper discusses the implementation and test strategy used in this work. Finally, the usability of the modeling approach and implemented timing analysis is demonstrated by modeling and time analyzing a vehicular application case study with the extended component model and tool suite.

  • 299.
    Askling, Kim
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Application of Topic Models for Test Case Selection: A comparison of similarity-based selection techniques2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Regression testing is just as important for the quality assurance of a system, as it is time consuming. Several techniques exist with the purpose of lowering the execution times of test suites and provide faster feedback to the developers, examples are ones based on transition-models or string-distances. These techniques are called test case selection (TCS) techniques, and focuses on selecting subsets of the test suite deemed relevant for the modifications made to the system under test.

    This thesis project focused on evaluating the use of a topic model, latent dirichlet allocation, as a means to create a diverse selection of test cases for coverage of certain test characteristics. The model was tested on authentic data sets from two different companies, where the results were compared against prior work where TCS was performed using similarity-based techniques. Also, the model was tuned and evaluated, using an algorithm based on differential evolution, to increase the model’s stability in terms of inferred topics and topic diversity.

    The results indicate that the use of the model for test case selection purposes was not as efficient as the other similarity-based selection techniques studied in work prior to thist hesis. In fact, the results show that the selection generated using the model performs similar, in terms of coverage, to a randomly selected subset of the test suite. Tuning of the model does not improve these results, in fact the tuned model performs worse than the other methods in most cases. However, the tuning process results in the model being more stable in terms of inferred latent topics and topic diversity. The performance of the model is believed to be strongly dependent on the characteristics of the underlying data used to train the model, putting emphasis on word frequencies and the overall sizes of the training documents, and implying that this would affect the words’ relevance scoring to the better.

  • 300.
    Aslam Butt, Haseeb
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Investigation into tools to increase Observability of 2oo2 OS based Generic Product2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    2 out of 2 (2oo2) OS-baserade system är en generisk plattform som Bombardier Transportation använder för att utveckla säkerhetskritiska järnvägsprodukter som uppfyller kraven för SIL 3 och SIL 4. 2oo2-arkitekturen är baserad på en kombination av designtekniker för felsäkerhet. Vid utvecklingen av en specialiserad produkt är felsökning och optimering vitala delar för att få ut produkten på marknaden i tid. Med verktyg som kan öka observerbarheten hos ett system kan felsökningsoch optimeringsprocesserna effektiviseras.Denna avhandling utforskar tillgängligheten av verktyg som ökar observerbarheten hos 2oo2 OS-baserade system. Spårningsoch profileringstekniker identifierades som möjliga tekniker för att förbättra observerbarheten. Verktyg för de identifierade teknikerna studerades utförligt för att undersöka möjligheterna att bygga, konfigurera och överföra dessa till den 2oo2-baserade arkitekturen. Det var möjligt att utveckla den fullständiga verktygskedjan för användning i testmiljö. Observerbarhetsinfrastrukturen utformades för att extrahera spårningsdata från maskin till analysverktyg. Procedurer togs fram för att använda spårningsdatan för att på ett effektivt sätt felsöka och optimera systemet. Dessutom undersöks även inverkan av systemuppgraderingar för att öka observerbarheten hos 2oo2-systemet.

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