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  • 501.
    Vergara Alonso, Ekhiotz Jon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Energy Modelling and Fairness for Efficient Mobile Communication2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

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

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

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

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

  • 502.
    Vergara Alonso, Ekhiotz Jon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Exploiting Energy Awareness in Mobile Communication2013Licentiate thesis, monograph (Other academic)
    Abstract [en]

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

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

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

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

  • 503.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Andersson, Simon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    When Mice Consume Like Elephants: Instant Messaging Applications2014In: e-Energy '14: Proceedings of the 5th international conference on Future energy systems, ACM Press, 2014, 97-107 p.Conference paper (Refereed)
    Abstract [en]

    A recent surge in the usage of instant messaging (IM) applications on mobile devices has brought the energy efficiency of these applications into focus of attention. Although IM applications are changing the message communication landscape, this work illustrates that the current versions of IM applications differ vastly in energy consumption when using the third generation (3G) cellular communication. This paper shows the interdependency between energy consumption and IM data patterns in this context. We analyse the user interaction pattern using a IM dataset, consisting of 1043370 messages collected from 51 mobile users. Based on the usage characteristics, we propose a message bundling technique that aggregates consecutive messages over time, reducing the energy consumption with a trade-off against latency. The results show that message bundling can save up to 43% in energy consumption while still maintaining the conversation function. Finally, the energy cost of a common functionality used in IM applications that informs that the user is currently typing a response, so called typing notification, is evaluated showing an energy increase ranging from 40-104%.

  • 504.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    EnergyBox: A Trace-driven Tool for Data Transmission Energy Consumption Studies2013In: EE-LSDS 2013, Energy Efficiency in Large Scale Distributed Systems, Springer, 2013, 19-34 p.Conference paper (Refereed)
    Abstract [en]

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

  • 505.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Fairness and Incentive Considerations in Energy Apportionment Policies2016In: ACM Transactions on Modeling and Performance Evaluation of Computing Systems, ISSN 2376-3639, Vol. 2, no 1Article in journal (Refereed)
    Abstract [en]

    The energy consumption of a system is determined by the system component usage patterns and interactions between the coexisting entities and resources. Energy accounting plays an essential role to reveal the contribution of each entity to the total consumption and for energy management. Unfortunately, energy accounting inherits the apportionment problem of accounting in general, which does not have a general single best solution. In this paper we leverage cooperative game theory commonly used in cost allocation problems to study the energy apportionment problem, i.e., the problem of prescribing the actual energy consumption of a system to the consuming entities (e.g., applications, processes or users of the system).

    We identify five relevant fairness properties for energy apportionment and present a detailed categorisation and analysis of eight previously proposed energy apportionment policies from different fields in computer and communication systems. In addition, we propose two novel energy apportionment policies based on cooperative game theory which provide strong fairness notion and a rich incentive structure. Our comparative analysis in terms of the identified five fairness properties as well as information requirement and computational complexity shows that there is a trade-off between fairness and the other evaluation criteria. We provide guidelines to select an energy apportionment policy depending on the purpose of the apportionment and the characteristics of the system.

  • 506.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Watts2Share: Energy-Aware Traffic Consolidation2013In: Green Computing and Communications (GreenCom), 2013 IEEE and Internet of Things (iThings/CPSCom), IEEE International Conference on and IEEE Cyber, Physical and Social Computing, IEEE Computer Society, 2013, 14-22 p.Conference paper (Refereed)
    Abstract [en]

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

  • 507.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Sharing the Cost of Lunch: Energy Apportionment Policies2015In: Proceedings of the 11th ACM Symposium on QoS and Security for Wireless and Mobile Networks, ACM Digital Library, 2015, 91-97 p.Conference paper (Refereed)
    Abstract [en]

    Energy consumption has become a hot topic in computer and communication technologies pinpointing the need to carefully analyse system efficiency. The energy consumption of a system is determined by the usage patterns of system components and complex interactions between the coexisting entities and resources. Providing transparency of a system’s consumption by breaking down the total consumption is vital to evaluate and provide energy-efficient design and operation.

    In this paper we survey the apportionment problem in different fields such as computer systems, wireless sensor networks, mobile devices and energy-efficient buildings. The challenge lies in how to attribute a share of the total energy consumption to the responsible entities (e.g., applications, processes or users of the system). Our analysis identifies that energy apportionment is a common problem in different fields and reviews five previously applied energy apportionment policies. Also, the work identifies relevant further research.

  • 508.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Prihodko, Mihails
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    EnergyBox: Disclosing the wireless transmission energy cost for mobile devices2014In: Sustainable Computing: Informatics and Systems, ISSN 2210-5379, Vol. 4, no 2, 118-135 p.Article in journal (Refereed)
    Abstract [en]

    While evolving mobile technologies bring millions of users closer to the vision of information anywhere-anytime, device battery depletions still hamper the quality of experience to a great extent. The energy consumption of data transmission is highly dependent on the traffic pattern, and we argue that designing energy efficient data transmissions starts by energy awareness. Our work proposes EnergyBox, a parametrised tool that facilitates accurate and repeatable energy consumption studies for 3G and WiFi transmissions at the user end using real traffic data.

    The tool takes as input the parameters of a network operator and the power draw for a given mobile device in the 3G and WiFi transmission states. It outputs an estimate of the consumed energy for a given packet trace, either synthetic or captured in a device using real applications. Using nine different applications with different data patterns the versatility and accuracy of the tool was evaluated. The evaluation was carried out for a modern and popular smartphone in the WiFi setting, a specific mobile broadband module for the 3G setting, and within the operating environment of a major mobile operator in Sweden. A comparison with real power traces indicates that EnergyBox is a valuable tool for repeatable and convenient studies. It exhibits an accuracy of 94–99% for 3G, and 95–99% for WiFi given the studied applications’ traces.

    Next the tool was deployed in a use case where a location sharing application was ran on top of two alternative application layer protocols (HTTP and MQTT) and with two different data exchange formats (JSON and Base64). The illustrative use case helped to identify the appropriateness of the pull and push strategies in sharing location data, and the benefit of EnergyBox in characterising where the breaking point lies for preferring one or the other protocol, under which network load, or exchange data format.

  • 509.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Prihodko, Mihails
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Mobile Location Sharing: An Energy Consumption Study2013In: e-Energy '13 Proceedings of the 4th International Conference on Future Energy Systems: Where Energy, Computing and Communication Meet, New York, NY, USA: ACM Press, 2013, 289-290 p.Conference paper (Refereed)
    Abstract [en]

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

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

  • 510.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Sanjuan, Joseba
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Kernel Level Energy-Efficient 3G Background Traffic Shaper for Android Smartphones2013Conference paper (Refereed)
    Abstract [en]

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

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

  • 511.
    Vergara, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Energy-aware Cross-layer Burst Buffering for Wireless Communication2012In: e-Energy '12 Proceedings of the 3rd International Conference on Future Energy Systems: Where Energy, Computing and Communication Meet, ACM , 2012Conference paper (Other academic)
    Abstract [en]

    The massive explosion of mobile applications with the ensuing data exchange over the cellular infrastructure is not only a blessing to the mobile user but also has a price in terms of regular discharging of the device battery. A big contributor to this energy consumption is the power hungry wireless network interface. We leverage a measurement kit to perform accurate physical energy consumption measurements in a third generation (3G) telecommunication modem thus isolating the energy footprint of data transfers as opposed to other mobile phone-based measurement studies. Using the measurement kit we show how the statically configured network parameters, i.e., channel switch timers, and buffer thresholds, in addition to the transfer data pattern and the radio coverage, impact the communication energy footprint. We then demonstrate that being aware of static network parameters creates room for energy savings. This is done by devising a set of algorithms that (a) infer the network parameters efficiently, and (b) use the parameters in a new packet scheduler in the device. The combined regime is shown to transfer background uplink data, from real world traces of Facebook and Skype, with significant energy saving compared to the state-of-the-art.

  • 512.
    Viel, Brieuc
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Why is fingerprint-based indoor localization still so hard?2014In: IEEE International Conference on Pervasive Computing and Communications Workshops (PERCOM Workshops), IEEE Computer Society, 2014, 443-448 p.Conference paper (Refereed)
    Abstract [en]

    Wireless indoor localization systems and especially signal strength fingerprinting techniques have been the subject of significant research efforts in the last decades. However, most of the proposed solutions require a costly site-survey to build the radio map which can be used to match radio signatures with specific locations. We investigate a novel indoor localization system that addresses the data collection problem by progressively and semi-autonomously creating a radio-map with limited interaction cost. Moreover, we investigate how spatiotemporal and hardware properties-based variations can affect the RSSI values collected and significantly influence the resulting localization. We show the impact of these fluctuations on our system and discuss possible mitigations.

  • 513.
    Vincelette, Erik
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Forecast: Beräkningar på affärs data2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    RemoteX Technologies AB är ett mjukvaruföretag i Stockholm. De utvecklar branschlösningar för ärendehantering och administration inom och mellan företrädandevis serviceföretag, ex. fastighetsförvaltning, VVS och byggbolag. Deras produkt heter RemoteX Applications och har sedan ett par månader tillbaka en möjlighet att kunna generera jobb utifrån fördefinierade scheman, vilket säkerställer att man kan hantera sina åtaganden i form av ronderingar och planerat underhåll. Deras kunder saknar dock en möjlighet att se vad den samlade mängden scheman kommer att generera framåt i tiden.Detta examensarbete syftar till att bygga en simulator för att beräkna hur mycket jobb som genereras och visa upp detta i ett webbgränssnitt. Simulatorn kommer skrivas i C# och hämta data från bakomliggande databas med LINQ to SQL och fokus ligger på att göra simuleringen så effektiv som möjligt med de tekniker som används. Webbgränssnittet skrivs i HTML5 och JavaScript och använder sig av färdiga JavaScript bibliotek för att visualisera prognosen som skapas av simulatorn.En slutpunkt har byggts i RemoteX REST API som tillhandahåller prognoser 6 månader framåt i tiden. Det går att ge parametrar till slutpunkten för att filtrera sin prognos ytterligare. En front-end som är en ny vy inom planning modulen har skapats och denna kommunicerar med slutpunkten. Denna front-end visualiserar prognosen i form av en agenda.

  • 514.
    Vogel, Harald
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Enhetstestning inom PL/SQL - en fallstudie2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Att ha ett väl fungerande automatiskt testsystem är allt viktigare inom mjukvaruutveckling. Tyvärr är det fortfarande vanligt med företag som framförallt förlitar sig på manuell testning i olika former vilket för med sig en rad problem. Extra svårt blir det för de ovanligare programmeringsspråken, som inte har samma historia av automatisk testning som andra språk. Genom att implementera enhetstestning på liten skala på ett riktigt system i PL/SQL och mäta resultaten, kan flera slutsatser dras om enhetstestnings duglighet. Enhetstestning tar betydligt kortare tid att exekvera än motsvarande tester manuellt och kan lätt återupprepas. De kan även testa kombinationer som är omöjliga eller mycket svåra att utföra manuellt, och de minskar tiden det tar att rätta buggar. Att skriva enhetstester tar initialt mycket tid och kräver en viss kunskap. Det kan även dröja innan enhetstester börjar ge resultat och de behöver underhållas allt eftersom att koden ändras. 

  • 515.
    Walander, Tomas
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Larsson, David
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Critical success factors in Agile software development projects2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 516.
    Wang, Q.
    et al.
    Embedded Intelligent Solutions (EIS) By Semcon AB, Linköping, Sweden.
    Wallin, A.
    Embedded Intelligent Solutions (EIS) By Semcon AB, Linköping, Sweden.
    Izosimov, Viacheslav
    Embedded Intelligent Solutions (EIS) By Semcon AB, Linköping, Sweden.
    Ingelsson, Urban
    Embedded Intelligent Solutions (EIS) By Semcon AB, Linköping, Sweden.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Test tool qualification through fault injection2012In: Test Symposium (ETS 2012), IEEE , 2012Conference paper (Other academic)
    Abstract [en]

    According to ISO 26262, a recent automotive functional safety standard, verification tools shall undergo qualification, e.g. to ensure that they do not fail to detect faults that can lead to violation of functional safety requirements. We present a semi-automatic qualification method involving a monitor and fault injection that reduce cost in the qualification process. We experiment on a verification tool implemented in LabVIEW.

  • 517.
    Wen, Liang
    et al.
    University of Elect Science and Technology China, Peoples R China.
    Jiang, Wei
    University of Elect Science and Technology China, Peoples R China.
    Jiang, Ke
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Zhang, Xia
    University of Texas Dallas, TX USA.
    Pan, Xiong
    University of Elect Science and Technology China, Peoples R China.
    Zhou, Keran
    University of Elect Science and Technology China, Peoples R China.
    Detecting Fault Injection Attacks on Embedded Real-Time Applications: A System-Level Perspective2015In: 2015 IEEE 17TH INTERNATIONAL CONFERENCE ON HIGH PERFORMANCE COMPUTING AND COMMUNICATIONS, 2015 IEEE 7TH INTERNATIONAL SYMPOSIUM ON CYBERSPACE SAFETY AND SECURITY, AND 2015 IEEE 12TH INTERNATIONAL CONFERENCE ON EMBEDDED SOFTWARE AND SYSTEMS (ICESS), IEEE , 2015, 700-705 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents an approach to the synthesis of secure real-time applications mapped on distributed embedded systems, which focuses on preventing fault injection attacks. We utilize symmetric cryptographic service to protect confidentiality, and deploy fault detection within confidential algorithm to resist fault injection attacks. Several fault detection schemes are identified, and their fault coverage rates and time overheads are derived and measured, respectively. Our synthesis approach makes efforts to determine the best fault detection schemes for the encryption/decryption of messages, such that the overall security strength of resisting fault injection attack is minimized, and the deadline constraint of the real-time applications is guaranteed. Since addressing the problem is still a NP-hard problem, we propose an efficient algorithm based on Fruit fly Optimization Algorithm (FOA), which can achieve better results by lower time overheads, compared with simulated annealing algorithm. Extensive experiments demonstrate the superiority of our approach.

  • 518.
    Wennberg, Per
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Danielson, Viktor
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Evaluation of a Testing Process to Plan and Implement an Improved Test System: A Case Study, Evaluation and Implementation in Lab-VIEW/TestStand2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order to ensure the quality of a product, the provider of the product must performcomplete testing of the product. This fact increases the demands on the test systems usedto conduct the testing, the system needs to be reliable.When developing new software for a company, sometimes a requirements specificationcreated at the beginning of the project is not enough. Details of the desired implementationmay get lost when working with a general requirements specification.This thesis presents a case study of how a certain company work with their test systems.The aim of the case study was to find where the largest points of improvements could bemade in a new test system, which was to be implemented during this thesis work. Theimplementation of this new system was done in LabVIEW in conjunction with TestStandand this process is covered in this thesis.The performed case study revealed that the employees at the company found robustnessand usability to be the key factors in a new test system. During and after the implementationof the new system, it was evaluated regarding these two metrics, this process isalso covered in this thesis.

  • 519.
    Wiberg, Fabian
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Patterns for Injection of Mock Objects in a Modeling Environment2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Capsules are modeling language elements which are sometimes used to develop real-time software. One way to test such capsule elements without relying on dependencies to other units is to use mock objects. The aim of the study was to look at existing object-oriented design patterns and investigate how they could be used for capsules, in order to perform mock testing. The focus was to find solutions that were usable from the programmers’ point of view, meaning that they should promote high user effectiveness, efficiency and satisfaction when implementing them. It was also important that program efficiency wasn’t affected negatively. 5 design- or refactoring patterns were adapted for capsules: Constructor Injection, Setter Injection, Parameterize Method, Factory Method and Abstract Factory. Those patterns were evaluated by 5 programmers in a usability test, where Incarnate Injection (an adaptation of Constructor Injection) and Abstract Factory were considered most usable. Incarnate Injection seemed to be easier to implement and promoted high user efficiency, while Abstract Factory was considered more flexible. The performance tests indicated that Abstract Factory compromises program efficiency when the factory product is resource-heavy and is required frequently by dependent capsules. The study showed that it is possible to adapt design patterns to capsules by looking at conceptual similarities between capsules and classes. However, there are cases when this adaptation is impossible. Furthermore, even when adaptation is possible, it was apparent that different patterns adapt differently well to capsules.

  • 520.
    Wilander, John
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Contributions to Specification, Implementation, and Execution of Secure Software2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis contributes to three research areas in software security, namely security requirements and intrusion prevention via static analysis and runtime detection.

    We have investigated current practice in security requirements by doing a field study of eleven requirement specifications on IT systems. The conclusion is that security requirements are poorly specified due to three things:  inconsistency in the selection of requirements, inconsistency in level of detail, and almost no requirements on standard security solutions. A follow-up interview study addressed the reasons for the inconsistencies and the impact of poor security requirements. It shows that the projects had relied heavily on in-house security competence and that mature producers of software compensate for poor requirements in general but not in the case of security and privacy requirements specific to the customer domain.

    Further, we have investigated the effectiveness of five publicly available static analysis tools for security. The test results show high rates of false positives for the tools building on lexical analysis and low rates of true positives for the tools building on syntactical and semantical analysis. As a first step toward a more effective and generic solution we propose decorated dependence graphs as a way of modeling and pattern matching security properties of code. The models can be used to characterize both good and bad programming practice as well as visually explain code properties to programmers. We have implemented a prototype tool that demonstrates how such models can be used to detect integer input validation flaws.

    Finally, we investigated the effectiveness of publicly available tools for runtime prevention of buffer overflow attacks. Our initial comparison showed that the best tool as of 2003 was effective against only 50 % of the attacks and there were six attack forms which none of the tools could handle. A follow-up study includes the release of a buffer overflow testbed which covers 850 attack forms. Our evaluation results show that the most popular, publicly available countermeasures cannot prevent all of these buffer overflow attack forms.

  • 521.
    Wrona, Michal
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Local-to-Global Consistency Implies Tractability of Abduction2014Conference paper (Refereed)
  • 522.
    Wrona, Michal
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Syntactically Characterizing Local-to-Global Consistency in ORD-Horn2012Conference paper (Other academic)
    Abstract [en]

    Establishing local consistency is one of the most frequently used algorithmic techniques in constraint satisfaction in general and in spatial and temporal reasoning in particular. A collection of constraints is globally consistent if it is completely explicit, that is, every partial solution may be extended to a full solution by greedily assigning values to variables one at a time. We will say that a structure B has local-to-global consistency if establishing local-consistency yields a globally consistent instance of CSP(B) .

    This paper studies local-to-global consistency for ORD-Horn languages, that is, structures definable over the ordered rationals (ℚ; < ) within the formalism of ORD-Horn clauses. This formalism has attracted a lot of attention and is of crucial importance to spatial and temporal reasoning. We provide a syntactic characterization (in terms of first-order definability) of all ORD-Horn languages enjoying local-to-global consistency.

  • 523.
    Wrona, Michal
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Tractability Frontier for Dually-Closed Ord-Horn Quantified Constraint Satisfaction Problems2014In: MATHEMATICAL FOUNDATIONS OF COMPUTER SCIENCE 2014, PT I, Springer Berlin/Heidelberg, 2014, Vol. 8634, 535-546 p.Conference paper (Refereed)
    Abstract [en]

    A temporal constraint language is a relational structure with a first-order definition in the rational numbers with the order. We study here the complexity of the Quantified Constraint Satisfaction Problem (QCSP) for Ord-Horn languages: probably the most widely studied family of all temporal constraint languages.

    We restrict ourselves to a natural subclass that we call dually-closed Ord-Horn languages. The main result of the paper states that the QCSP for a dually-closed Ord-Horn language is either in P or it is coNP-hard.

  • 524.
    Zadegan, Farrokh Ghani
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Carlsson, Gunnar
    Ericsson, Linköping, Sweden.
    Larsson, Erik
    Lund University, Sweden.
    Scenario-Based Network Design for P16872013In: SSoCC'13, 2013Conference paper (Other academic)
    Abstract [en]

    To improve testability of integrated circuits against manufacturing defects, and to better handle the complexity of modern designs during debugging and characterization, it is common to embed testing, debugging, configuration, and monitoring features (called on-chip instruments) within the chip. IEEE P1687 proposes a flexible network for accessing and operating such on-chip instruments from outside the chip, and facilitates reusing instrument access procedures in different usage scenarios throughout the chip's life-cycle-spanning from chip prototyping to in-field test. Efficient access (in terms of time) to on-chip instruments requires careful design of the instrument access network. However, it is shown that a network optimized for one usage scenario, is not necessarily efficient in other scenarios. To address the problem of designing a network which is efficient in terms of instrument access time under multiple scenarios, in this work, we compare a number of network design approaches provided by P1687, in terms of instrument access time and hardware overhead.

  • 525.
    Zadegan, Farrokh Ghani
    et al.
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Ingelsson, Urban
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Asani, Golnaz
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Carlsson, Gunnar
    Ericsson, Linköping, Sweden.
    Larsson, Erik
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Test Scheduling in an IEEE P1687 Environment with Resource and Power Constraints2011In: Proceedings of the Asian Test Symposium, IEEE , 2011, 525-531 p.Conference paper (Refereed)
    Abstract [en]

    In contrast to IEEE 1149.1, IEEE P1687 allows, through segment insertion bits, flexible scan paths for accessing on-chip instruments, such as test, debug, monitoring, measurement and configuration features. Flexible access to embedded instruments allows test time reduction, which is important at production test. However, the test access scheme should be carefully selected such that resource constraints are not violated and power constraints are met. For IEEE P1687, we detail in this paper session-based and session-less test scheduling, and propose resource and power-aware test scheduling algorithms for the detailed scheduling types. Results using the implementation of our algorithms shows on ITC’02-based benchmarks significant test time reductions when compared to non-optimized test schedules.

  • 526.
    Zadegan, Farrokh Ghani
    et al.
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Ingelsson, Urban
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Carlsson, Gunnar
    Ericsson, Linköping, Sweden.
    Larsson, Erik
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Automated Design for IEEE P16872011In: The 11th Swedish System-on-Chip Conference, Varberg, Sweden, May 2-3, 2011., 2011Conference paper (Other academic)
  • 527.
    Zeng, Haibo
    et al.
    Department of Electrical and Computer Engineering, Virginia Tech.
    Joshi, Prachi
    Department of Electrical and Computer Engineering, Virginia Tech.
    Thiele, Daniel
    Elektrobit Automotive GmbH.
    Diemer, Jonas
    Symtavision.
    Axer, Philip
    NXP Semiconductors.
    Ernst, Rolf
    Institut für Datentechnik und Kommunikationsnetze, Technische Universität Braunschweig.
    Eles, Petru
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Networked Real-Time Embedded Systems2017In: Handbook of Hardware/Software Codesign, Springer Netherlands, 2017, 1-40 p.Chapter in book (Refereed)
    Abstract [en]

    This chapter gives an overview on various real-time communication protocols, from the Controller Area Network (CAN) that was standardized over twenty years ago but is still popular, to the FlexRay protocol that provides strong predictability and fault tolerance, to the more recent Ethernet-based networks. The design of these protocols including their messaging mechanisms was driven by diversified requirements on bandwidth, real-time predictability, reliability, cost, etc. The chapter provides three examples of real-time communication protocols: CAN as an example of event-triggered communication, FlexRay as a heterogeneous protocol supporting both time-triggered and event-triggered communications, and different incarnations of Ethernet that provide desired temporal guarantees.

  • 528.
    Zhang, Xia
    et al.
    University of Electronic Science and Technology, China.
    Zhang, Jinyu
    University of Electronic Science and Technology, China.
    Jiang, Wei
    University of Electronic Science and Technology, China.
    Ma, Yue
    University of Electronic Science and Technology, China.
    Jiang, Ke
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Design Optimization of Security-Sensitive Mixed-Criticality Real-Time Embedded Systems2013Conference paper (Refereed)
    Abstract [en]

    In this paper we are interested in securitysensitive mixed-criticality real-time systems. Existing researches on mixed-criticality systems usually are safety-oriented, which seriously ignore the security requirements. We firstly establish the system model to capture security-critical applications in mixed-criticality systems. Higher security-criticality protection always results in significant time and energy overhead in mixedcriticality systems. Thus, this paper proposes a system-level design framework for energy optimization of security-sensitive mixed-criticality system. Since the time complexity of finding optimal solutions grows exponentially as problem size grows, a GA based efficient heuristic algorithm is devised to address the system-level optimization problem. Extensive experiments demonstrate the efficiency of the proposed technique, which can obtain balanced minimal energy consumption while satisfying strict security and timing constraints.

  • 529.
    Zhang, Ying
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Li, Huawei
    Institute of Computing Technology, Chinese Academy of Sciences, Beijing, China.
    Li, Xiaowei
    Institute of Computing Technology, Chinese Academy of Sciences, Beijing, China.
    Automatic Test Program Generation Using Executing Trace Based Constraint Extraction for Embedded Processors2013In: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, Vol. 21, no 7, 1220-1233 p.Article in journal (Refereed)
    Abstract [en]

    Software-based self-testing (SBST) has been a promising method for processor testing, but the complexity of the state-of-art processors still poses great challenges for SBST. This paper utilizes the executing trace collected during executing training programs on the processor under test to simplify mappings and functional constraint extraction for ports of inner components, which facilitate structural test generation with constraints at gate level, and automatic test instruction generation (ATIG) even for hidden control logic (HCL). In addition, for sequential HCL, we present a test routine generation technique on the basis of an extended finite state machine, so that structural patterns for combinational subcircuits in the sequential HCL can be mapped into the test routines to form a test program. Experimental results demonstrate that the proposed ATIG method can achieve good structural fault coverage with compact test programs on modern processors.

  • 530.
    Zhang, Ying
    et al.
    School of Software Engineering, Tongji University, China.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Jiang, Jianhui
    School of Software Engineering, Tongji University, China.
    Li, Huawei
    State Key Laboratory of Computer Architecture, Institute of Computing Technology, Chinese Academy of Sciences, China.
    Fujita, Masahiro
    VLSI Design and Education Center, University of Tokyo, Japan .
    Temperature-Aware Software-Based Self-Testing for Delay Faults2015In: Proc. Design, Automation and Test in Europe Conference (DATE’15), Grenoble, France, Mar. 9-13, 2015., 2015Conference paper (Refereed)
    Abstract [en]

    Delay defects under high temperature have been one of the most critical factors to affect the reliability of computer systems, and the current test methods don’t address this problem properly. In this paper, a temperature-aware software-based selftesting (SBST) technique is proposed to self-heat the processors within a high temperature range and effectively test delay faults under high temperature. First, it automatically generates highquality test programs through automatic test instruction generation (ATIG), and avoids over-testing caused by nonfunctional patterns. Second, it exploits two effective powerintensive program transformations to self-heat up the processors internally. Third, it applies a greedy algorithm to search the optimized schedule of the test templates in order to generate the test program while making sure that the temperature of the processor under test is within the specified range. Experimental results show that the generated program is successful to guarantee delay test within the given temperature range, and achieves high test performance with functional patterns.

  • 531.
    Zhang, Ying
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Eles, Petru
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Automatic Test Program Generation for Out-of-Order Superscalar Processors2012In: 21st IEEE Asian Test Symposium (ATS12), Niigata, Japan, November 19-22, 2012., IEEE, 2012Conference paper (Refereed)
    Abstract [en]

    This paper presents a high-level automatic test instruction generation (HATIG) technical that allows, for the first time, to test the scheduling unit of an out-of-order super scalar processor. This technique leverages on existing bounded model checking tools in order to generate software-based self-testing programs from a global EFSM model of the processor under test. The experimental results have demonstrated the efficiency of the proposed technique.

  • 532.
    Ögren, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Wikblad, Ludwig
    Linköping University, Department of Computer and Information Science, Software and Systems.
    En testprocess för webbutvecklingsprojekt med små team2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Finding a suitable approach for testing in small development teams is a challenge. Many small companies view traditional test processes and test process improvement models as too resource intensive for their needs. Minimal Test Practice Framework (MTPF) is a framework for testing which purpose is to provide a minimalistic approach to test improvement. The goal of this study was to examine how MTPF can be adapted to a small development team without incurring a time cost that the team would experience as too high. The study was performed in the department Web \& Mobile of the company Exsitec. At the department teams of 2-6 people develop web applications to business customers. During the study a testprocess was developed in close cooperation with the developers of the department with the aim of adapting it as well as possible to the needs of the department. The study was performed as action research in three phases, according to the method Cooperative Method Development, in a project with two developers. During the first phase all developers in the department were interviewed to establish an understanding of the environment for the study. During the second phase a set of possible improvements was developed together with the developers. During the third phase some of these improvements were implemented and evaluated. By focusing on unit testing central business logic in the application the developed test process improved the developers confidence in the code quality without being perceived as too resource intensive.

  • 533.
    Öhlin, Petra
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Prioritizing Tests with Spotify’s Test & Build Data using History-based, Modification-based & Machine Learning Approaches2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis intends to determine the extent to which machine learning can be used to solve the regression test prioritization (RTP) problem. RTP is used to order tests with respect to probability of failure. This will optimize for a fast failure, which is desirable if a test suite takes a long time to run or uses a significant amount of computational resources. A common machine learning task is to predict probabilities; this makes RTP an interesting application of machine learning. A supervised learning method is investigated to train a model to predict probabilities of failure, given a test case and a code change. The features investigated are chosen based on previous research of history- based and modification-based RTP. The main motivation for looking at these research areas is that they resemble the data provided by Spotify. The result of the report shows that it is possible to improve how tests run with RTP using machine learning. Nevertheless, a much simpler history- based approach is the best performing approach. It is looking at the history of test results, the more failures recorded for the test case over time, the higher priority it gets. Less is sometimes more. 

  • 534.
    Östman, Nicklas
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Lindström, Rasmus
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Vertically Scaling Agile: A Multiple-Case Study2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The conceptual framework of agile software development is an ever-growing movement in the software industry. However, recent studies have shown that large, less software-focused companies, where software development is primarily used for in-house IT-solutions, struggle with giving up traditional command-control type of management. This hits hard on some of the most important principles of agile software development and in many cases this phenomenon has inevitably led to large gaps between development teams and more managerial parts of the organization. This thesis has aimed to study this gap and investigate how it affects software development teams’ ability to carry out their work.

    By comparing three software teams that were internally highly similar but with varying external conditions, impact on the teams’ behaviour based on their different environments was studied. The study was carried out using a multiple-case study approach with primary data sources consisting of survey gathered data from all team members and interviews with a subset of the team members. The results gathered from this study suggest that agile development teams are extremely dependent on a well-functioning interface to business related parts of an organization. Regarding teams’ ability to make decisions and being agile in their way of working, the results primarily isolate impediments with roots in an unwillingness to adhere to and lack of understanding of agile principles.

    In this thesis, our gathered results were also correlated with a modern framework called Flow in order to confirm its relevance regarding analyzing software development teams in large-scale environments. 

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