liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 24 of 24
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Amirijoo, Mehdi
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    QoS Control of Real-Time Data Services under Uncertain Workload2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Real-time systems comprise computers that must generate correct results in a timely manner. This involves a wide spectrum of computing systems found in our everyday life ranging from computers in rockets to our mobile phones. The criticality of producing timely results defines the different types of realtime systems. On one hand, we have the so-called hard real-time systems, where failing to meet deadlines may result in a catastrophe. In this thesis we are, however, concerned with firm and soft real-time systems, where missing deadlines is acceptable at the expense of degraded system performance. The usage of firm and soft real-time systems has increased rapidly during the last years, mainly due to the advent of applications in multimedia, telecommunication, and e-commerce. These systems are typically data-intensive, with the data normally spanning from low-level control data, typically acquired from sensors, to high-level management and business data. In contrast to hard real-time systems, the environments in which firm and soft real-time systems operate in are typically open and highly unpredictable. For example, the workload applied on a web server or base station in telecommunication systems varies according to the needs of the users, which is hard to foresee. In this thesis we are concerned with quality of service (QoS) management of data services for firm and soft real-time systems. The approaches and solutions presented aim at providing a general understanding of how the QoS can be guaranteed according to a given specification, even if the workload varies unpredictably. The QoS specification determines the desired QoS during normal system operation, and the worst-case system performance and convergence rate toward the desired setting in the face of transient overloads. Feedback control theory is used to control QoS since little is known about the workload applied on the system. Using feedback control the difference between the measured QoS and the desired QoS is formed and fed into a controller, which computes a change to the operation of the real-time system. Experimental evaluation shows that using feedback control is highly effective in managing QoS such that a given QoS specification is satisfied. This is a key step toward automatic management of intricate systems providing real-time data services.

    List of papers
    1. Specification and Management of QoS in Real-Time Databases Supporting Imprecise Computations
    Open this publication in new window or tab >>Specification and Management of QoS in Real-Time Databases Supporting Imprecise Computations
    2006 (English)In: IEEE Transactions on Computers, ISSN 0018-9340, Vol. 55, no 3, p. 304 - 319Article in journal (Refereed) Published
    Abstract [en]

    Real-time applications such as e-commerce, flight control, chemical and nuclear control, and telecommunication are becoming increasingly sophisticated in their data needs, resulting in greater demands for real-time data services that are provided by real-time databases. Since the workload of real-time databases cannot be precisely predicted, they can become overloaded and thereby cause temporal violations, resulting in damage or even a catastrophe. Imprecise computation techniques address this problem and allow graceful degradation during overloads. In this paper, we present a framework for QoS specification and management consisting of a model for expressing QoS requirements, an architecture based on feedback control scheduling, and a set of algorithms implementing different policies and behaviors. Our approach gives a robust and controlled behavior of real-time databases, even for transient overloads and with inaccurate runtime estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms that uses feedback control.

    Keywords
    Real-time and embedded systems, real-time data services, imprecise computation, feedback control, modeling techniques
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12635 (URN)10.1109/TC.2006.45 (DOI)
    Available from: 2007-10-17 Created: 2007-10-17 Last updated: 2009-02-10
    2. Experimental Evaluation of Linear Time-Invariant Models for Feedback Performance Control in Real-Time Systems
    Open this publication in new window or tab >>Experimental Evaluation of Linear Time-Invariant Models for Feedback Performance Control in Real-Time Systems
    2007 (English)In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 35, no 3, p. 209-238Article in journal (Refereed) Published
    Abstract [en]

    In recent years a new class of soft real-time applications operating in unpredictable environments has emerged. Typical for these applications is that neither the resource requirements nor the arrival rates of service requests are known or available a priori. It has been shown that feedback control is very effective to support the specified performance of dynamic systems that are both resource insufficient and exhibit unpredictable workloads. To efficiently use feedback control scheduling it is necessary to have a model that adequately describes the behavior of the system. In this paper we experimentally evaluate the accuracy of four linear time-invariant models used in the design of feedback controllers. We introduce a model (DYN) that captures additional system dynamics, which a previously published model (STA) fails to include. The accuracy of the models are evaluated by validating the models with regard to measured data from the controlled system and through a set of experiments where we evaluate the performance of a set of feedback control schedulers tuned using these models. From our evaluations we conclude that second order models (e.g., DYN) are more accurate than first order models (e.g. STA). Further we show that controllers tuned using second order models perform better than controllers tuned using first order models.

    Place, publisher, year, edition, pages
    Springer Science+Business Media B.V., 2007
    Keywords
    Feedback control scheduling, Modeling, Model validation, System identification
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-12636 (URN)10.1007/s11241-006-9008-8 (DOI)
    Available from: 2007-10-17 Created: 2007-10-17 Last updated: 2017-12-14
    3. Robust Quality Management for Differentiated Imprecise Data Services
    Open this publication in new window or tab >>Robust Quality Management for Differentiated Imprecise Data Services
    2004 (English)In: Proceedings of the 25th IEEE International Real-Time Systems Symposium, 2004, p. 265-275Conference paper, Published paper (Refereed)
    Abstract [en]

    Several applications, such as Web services and e-commerce, are operating in open environments where the workload characteristics, such as the load applied on the system and the worst-case execution times, are inaccurate or even not known in advance. This implies that transactions submitted to a real-time database cannot be subject to exact schedulability analysis given the lack of a priori knowledge of the workload. In this paper we propose an approach, based on feedback control, for managing the quality of service of real-time databases that provide imprecise and differentiated services, given inaccurate workload characteristics. For each service class, the database operator specifies the quality of service requirements by explicitly declaring the precision requirements of the data and the results of the transactions. The performance evaluation shows that our approach provides reliable quality of service even in the face of varying load and inaccurate execution time estimates.

    Keywords
    Real-time systems, Real-time databases, Control theory, Realtidssystem, Realtidsdatabaser, Reglerteknik, CUGS
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-12637 (URN)10.1109/REAL.2004.49 (DOI)0-7695-2247-5 (ISBN)
    Conference
    25th IEEE International Real-Time Systems Symposium, Lisbon, Portugal, December 5-8, 2004
    Available from: 2007-10-17 Created: 2007-10-17 Last updated: 2018-08-30
    4. Generalized performance management of multi-class real-time imprecise data services
    Open this publication in new window or tab >>Generalized performance management of multi-class real-time imprecise data services
    Show others...
    2005 (English)In: Real-Time Systems Symposium, 2005. RTSS 2005. 26th IEEE International, 2005, p. 12-49Conference paper, Published paper (Other academic)
    Abstract [en]

    The intricacy of real-time data service management increases mainly due to the emergence of applications operating in open and unpredictable environments, increases in software complexity, and need for performance guarantees. In this paper we propose an approach for managing the quality of service of real-time databases that provide imprecise and differentiated services, and that operate in unpredictable environments. Transactions are classified into service classes according to their level of importance. Transactions within each service class are further classified into subclasses based on their quality of service requirements. In this way transactions are explicitly differentiated according to their importance and quality of service requests. The performance evaluation shows that during overloads the most important transactions are guaranteed to meet their deadlines and that reliable quality of service is provided even in the face of varying load and execution time estimation errors.

    Keywords
    real-time system, database, QoS, feedback control
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12638 (URN)10.1109/RTSS.2005.23 (DOI)
    Available from: 2007-10-17 Created: 2007-10-17 Last updated: 2009-04-22
    5. Quantifying and Suppressing the Measurement Disturbance in Feedback Controlled Real-Time Systems
    Open this publication in new window or tab >>Quantifying and Suppressing the Measurement Disturbance in Feedback Controlled Real-Time Systems
    2008 (English)In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 40, no 1, p. 44-76Article in journal (Refereed) Published
    Abstract [en]

    In the control of continuous and physical systems, the controlled system is sampled sufficiently fast to capture the dynamics of the system. In general, this property cannot be applied to the control of computer systems as the measured variables are often computed over a data set, e.g., deadline miss ratio. In this paper we quantify the disturbance present in the measured variable as a function of the data set size and the sampling period, and we propose a feedback control structure that suppresses the measurement disturbance. The experiments we have carried out show that a controller using the proposed control structure outperforms a traditional control structure with regard to performance reliability.

    Place, publisher, year, edition, pages
    Springer, 2008
    Keywords
    Adaptive scheduling, Feedback control, Measurement disturbance, System disturbance
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-12639 (URN)10.1007/s11241-008-9048-3 (DOI)
    Available from: 2007-10-17 Created: 2007-10-17 Last updated: 2017-12-14
  • 2.
    Amirijoo, Mehdi
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Brännström, Per
    Institutionen för datavetenskap Linköpings universitet.
    Hansson, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Gunnarsson, Svante
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Automatic Control.
    Son, Sang
    Department of Computer Science University of Virginia.
    Toward Adaptive Control of QoS-Importance Decoupled Real-Time Systems2007In: IEEE International Workshop on Feedback Control Implementation and Design in Computing Systems and Networks,2007, 2007Conference paper (Refereed)
    Abstract [en]

    This paper deals with differentiated services in real-time systems. Tasks submitted to a real-time system are differentiated with respect to importance and QoS requirements. We use feedback control to enforce the requirements in QoS and ensure a hierarchical admission policy based on the importance of the tasks. The results show that the requirements are met during steady state when the workload is constant. The feedback control approach does not satisfactorily manage QoS when there is a sudden and significant workload change (transient state) due to the time-variant nature of the system. To address this, we present preliminary and promising results using adaptive control, and report on some challenges we are facing when applying the theory.

  • 3.
    Amirijoo, Mehdi
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Chaufette, Nicolas
    Hansson, Jörgen
    Software Engineering Institute, Carnegie Mellon University, USA.
    Son, Sang H.
    Dept. of Computer Science, University of Virginia, Charlottesville, USA.
    Gunnarsson, Svante
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Generalized performance management of multi-class real-time imprecise data services2005In: Real-Time Systems Symposium, 2005. RTSS 2005. 26th IEEE International, 2005, p. 12-49Conference paper (Other academic)
    Abstract [en]

    The intricacy of real-time data service management increases mainly due to the emergence of applications operating in open and unpredictable environments, increases in software complexity, and need for performance guarantees. In this paper we propose an approach for managing the quality of service of real-time databases that provide imprecise and differentiated services, and that operate in unpredictable environments. Transactions are classified into service classes according to their level of importance. Transactions within each service class are further classified into subclasses based on their quality of service requirements. In this way transactions are explicitly differentiated according to their importance and quality of service requests. The performance evaluation shows that during overloads the most important transactions are guaranteed to meet their deadlines and that reliable quality of service is provided even in the face of varying load and execution time estimation errors.

  • 4.
    Amirijoo, Mehdi
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Gunnarsson, Svante
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Software Engineering Institute, Carnegie Mellon University, Pittsburgh, PA, USA.
    Son, Sang H.
    University of Virginia, USA.
    Quantifying and Suppressing the Measurement Disturbance in Feedback Controlled Real-Time Systems2008In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 40, no 1, p. 44-76Article in journal (Refereed)
    Abstract [en]

    In the control of continuous and physical systems, the controlled system is sampled sufficiently fast to capture the dynamics of the system. In general, this property cannot be applied to the control of computer systems as the measured variables are often computed over a data set, e.g., deadline miss ratio. In this paper we quantify the disturbance present in the measured variable as a function of the data set size and the sampling period, and we propose a feedback control structure that suppresses the measurement disturbance. The experiments we have carried out show that a controller using the proposed control structure outperforms a traditional control structure with regard to performance reliability.

  • 5.
    Amirijoo, Mehdi
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Gunnarsson, Svante
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Son, Sang H.
    University of Virginia, VA, USA.
    Enhancing Feedback Control Scheduling Performance by On-line Quantification and Suppression of Measurement Disturbance2005In: Proceedings of the 11th IEEE Real-Time and Embedded Technology and Applications Symposium, 2005, p. 2-11Conference paper (Refereed)
    Abstract [en]

    In the control of continuous and physical systems, the controlled system is sampled sufficiently fast to capture the system dynamics. In general, this property cannot be applied to the control of computer systems as the measured variables are often computed over a data set, e.g., deadline miss ratio. In this paper we quantize the disturbance present in the measured variable as a function of the sampling period and we propose a measurement disturbance suppressive control structure. The experiments we have carried out show that a controller using the proposed control structure outperforms a traditional control structure with regard to performance reliability and adaptation.

  • 6.
    Amirijoo, Mehdi
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Son, S. H.
    University of Virginia.
    Algorithms for Managing QoS for Real-Time Data Services Using Imprecise Computation2003In: Proceedings of the 9th International Conference on Real-Time and Embedded Computing Systems and Application (RTCSA 2003), Springer Verlag , 2003Conference paper (Refereed)
  • 7.
    Amirijoo, Mehdi
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Son, Sang H
    University of Virginia.
    Algorithms for managing QoS for real-time data services using imprecise computation2004In: Real-Time and Embedded Computing Systems and Applications 9th International Conference, RTCSA 2003, Tainan City, Taiwan, February 18-20, 2003. Revised Papers / [ed] Jing Chen and Seongsoo Hong, Springer Berlin/Heidelberg, 2004, Vol. 2968, p. 136-157Chapter in book (Refereed)
    Abstract [en]

    Lately the demand for real-time data services has increased in applications where it is desirable to process user requests within their deadlines using fresh data. The real-time data services are usually provided by a real-time database (RTDB). Here, since the workload of the RTDBs cannot be precisely predicted, RTDBs can become overloaded. As a result, deadline misses and freshness violations may occur. To address this problem we propose a QoS-sensitive approach to guarantee a set of requirements on the behavior of RTDBs. Our approach is based on imprecise computation, applied on both data and transactions. We propose two algorithms to dynamically balance the workload and the quality of the data and transactions. Performance evaluations show that our algorithms give a robust and controlled behavior of RTDBs, in terms of transaction and data quality, even for transient overloads and with inaccurate run-time estimates of the transactions.

  • 8.
    Amirijoo, Mehdi
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Hansson, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Son, Sang H
    Dept. of Computer Science University of Virginia.
    Error-Driven QoS Management in Imprecise Real-Time Databases2003In: Euromicro Conference on Real-Time Systems,2003, Los Alamitos, CA, USA: IEEE Computer Society , 2003, p. 63-Conference paper (Refereed)
    Abstract [en]

    In applications such as web-applications, e-commerce, and engine control, the demand for real-time data services has increased. In these applications, requests have to be processed within their deadlines using fresh data. Since the workload of these systems cannot be precisely predicted, they can become overloaded and as a result, deadline and freshness violations may occur. To address this problem we propose a QoS-sensitive approach based on imprecise computation, applied on transactions and data objects. We propose two algorithms FCS-HEF and FCS-HEDF that give a robust and controlled behavior of RTDBs in terms of transaction and data preciseness, even for transient overloads and with inaccurate run-time estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms including FCS-EDF, which schedules the transactions using EDF.

  • 9.
    Amirijoo, Mehdi
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Hansson, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Son, Sang H
    Dept. of Computer Science University of Virginia.
    Specification and Management of QoS in Imprecise Real-Time Databases2003In: International Database Engineering and Applications Symposium,2003, Los Alamitos, CA, USA: IEEE Computer Society , 2003, p. 192-Conference paper (Refereed)
    Abstract [en]

    Real-time applications such as e-commerce, flight control, chemical and nuclear control, and telecommunication are becoming increasingly sophisticated in their data needs, resulting in greater demands for real-time data services. Since the workload of real-time databases RTDBs, providing real-time data services, cannot be precisely predicted, they can become overloaded and thereby cause temporal violations, resulting in a damage or even a catastrophe. Imprecise computation techniques address this problem and allow graceful degradation during overloads. In this paper, we present a framework consisting of a model for expressing QoS requirements in terms of data and transaction preciseness, an architecture based on feedback control scheduling, and a set of algorithms implementing different policies and behaviors. Our approach gives a robust and controlled behavior of RTDBs, even for transient overloads and with inaccurate run-time estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms, including FCS-EDF that schedules the transactions using EDF and feedback control.

  • 10.
    Amirijoo, Mehdi
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Linköping University, Department of Computer and Information Science, RTSLAB. Linköping University, The Institute of Technology.
    Son, Sang H.
    Dept. of Computer Science, University of Virginia, Charlottesville, USA.
    Specification and Management of QoS in Real-Time Databases Supporting Imprecise Computations2006In: IEEE Transactions on Computers, ISSN 0018-9340, Vol. 55, no 3, p. 304 - 319Article in journal (Refereed)
    Abstract [en]

    Real-time applications such as e-commerce, flight control, chemical and nuclear control, and telecommunication are becoming increasingly sophisticated in their data needs, resulting in greater demands for real-time data services that are provided by real-time databases. Since the workload of real-time databases cannot be precisely predicted, they can become overloaded and thereby cause temporal violations, resulting in damage or even a catastrophe. Imprecise computation techniques address this problem and allow graceful degradation during overloads. In this paper, we present a framework for QoS specification and management consisting of a model for expressing QoS requirements, an architecture based on feedback control scheduling, and a set of algorithms implementing different policies and behaviors. Our approach gives a robust and controlled behavior of real-time databases, even for transient overloads and with inaccurate runtime estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms that uses feedback control.

  • 11.
    Amirijoo, Mehdi
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Son, Sang H.
    University of Virginia, USA.
    Gunnarsson, Svante
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Experimental Evaluation of Linear Time-Invariant Models for Feedback Performance Control in Real-Time Systems2007In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 35, no 3, p. 209-238Article in journal (Refereed)
    Abstract [en]

    In recent years a new class of soft real-time applications operating in unpredictable environments has emerged. Typical for these applications is that neither the resource requirements nor the arrival rates of service requests are known or available a priori. It has been shown that feedback control is very effective to support the specified performance of dynamic systems that are both resource insufficient and exhibit unpredictable workloads. To efficiently use feedback control scheduling it is necessary to have a model that adequately describes the behavior of the system. In this paper we experimentally evaluate the accuracy of four linear time-invariant models used in the design of feedback controllers. We introduce a model (DYN) that captures additional system dynamics, which a previously published model (STA) fails to include. The accuracy of the models are evaluated by validating the models with regard to measured data from the controlled system and through a set of experiments where we evaluate the performance of a set of feedback control schedulers tuned using these models. From our evaluations we conclude that second order models (e.g., DYN) are more accurate than first order models (e.g. STA). Further we show that controllers tuned using second order models perform better than controllers tuned using first order models.

  • 12.
    Amirijoo, Mehdi
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Son, Sang H.
    Department of Computer Science University of Virgina.
    Hansson, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    QoD Adaptation for Achieving Lifetime Predictability of WSN Nodes Communicating over Satellite Links2007In: International Conference on Networked Sensing Systems INSS,2007, IEEE , 2007, p. 19-26Conference paper (Refereed)
    Abstract [en]

    In this paper we propose an architecture consisting of a particular type of node, namely a communication server that collects and aggregates data, and establishes a link between the users and the sensor nodes through satellite communication. A key challenge with satisfying a lifetime requirement of the communication server is the unpredictability of the sensor data volume arriving at the communication server and the transmission power of the satellite terminal. To provide lifetime predictability we propose an approach that automatically adjusts the quality of the data such that the specified lifetime if achieved. We have shown through an extensive evaluation that the approach manages to provide an actual lifetime within 2% of the specified lifetime despite variations in workload and communication link quality.

  • 13.
    Amirijoo, Mehdi
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Tesanovic, Aleksandra
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Andersson, Torgny
    Enea Epact.
    Hansson, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Son, Sang H.
    Department of Computer Science University of Virginia, USA.
    Finite Horizon QoS Prediction of Reconfigurable Firm Real-Time Systems2006In: IEEE International Conference on Embedded and Real-Time Computing Systems and Applications,2006, Los Alamitos, California, USA: IEEE Computer Society , 2006, p. 233-Conference paper (Refereed)
    Abstract [en]

    Updating real-time system software is often needed in response to errors and added requirements to the software. Stopping a running application, updating the software, and then restarting the application is not suitable for systems with high availability requirements. On the other hand, dynamically updating a system may increase the execution time of the tasks, thus, degrading the performance of the system. Degradation is not acceptable for performance-critical real-time systems as there are strict requirements on the performance. In this paper we present an approach that enables dynamic reconfiguration of a real-time system, where the performance of the system during a reconfiguration satisfies a given worst-case performance specification. Evaluation shows that the presented method is efficient in guaranteeing the worst-case performance of dynamically reconfigurable firm real-time systems. 

  • 14.
    Amirijoo, Mehdi
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Tesanovic, Aleksandra
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Nadjm-Tehrani, Simin
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Raising Motivation in Real-time Laboratories: The Soccer Scenario2004In: Technical Symposium on Computer Science Education, SIGCSE,2004, USA: Association for Computing Machinery (ACM) , 2004, p. 265-Conference paper (Refereed)
    Abstract [en]

    Real-time systems is a topic that one cannot overlook in an engineer's education. However, teaching real-time systems in an undergraduate syllabus is a challenging experience due to conflicting constraints placed on such a course. In this paper we present a new setup for laboratories in the real-time systems course that successfully meets the constraints of mass education, stable environment management, short time span for the labs, and still enables deep involvement of students in the central topic of resource allocation with high motivation.

  • 15.
    Gunnarsson, Svante
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Amirijoo, Mehdi
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Son, Sang H
    University of Virginia, Charlottesville, USA.
    Robust Quality Management for Differentiated Imprecise Data Services2004In: Proceedings of the 25th IEEE International Real-Time Systems Symposium, 2004, p. 265-275Conference paper (Refereed)
    Abstract [en]

    Several applications, such as Web services and e-commerce, are operating in open environments where the workload characteristics, such as the load applied on the system and the worst-case execution times, are inaccurate or even not known in advance. This implies that transactions submitted to a real-time database cannot be subject to exact schedulability analysis given the lack of a priori knowledge of the workload. In this paper we propose an approach, based on feedback control, for managing the quality of service of real-time databases that provide imprecise and differentiated services, given inaccurate workload characteristics. For each service class, the database operator specifies the quality of service requirements by explicitly declaring the precision requirements of the data and the results of the transactions. The performance evaluation shows that our approach provides reliable quality of service even in the face of varying load and inaccurate execution time estimates.

  • 16. Kang, Woochul
    et al.
    Son, Sang H.
    Stankovic, John A.
    Amirijoo, Mehdi
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    I/O-Aware Deadline Miss Ratio Management in Real-Time Embedded Databases2008In: IEEE Real-Time Systems Symposium,2008, USA: IEEE , 2008Conference paper (Refereed)
  • 17.
    Larsson, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Amirijoo, Mehdi
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Karlsson, Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    Eles, Petru Ion
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory.
    What Impacts Course Evaluation?2007In: 12th SIGCSE Conf. on Innovation and Technology in Computer Science Education,2007, 2007, p. 333-333Conference paper (Refereed)
    Abstract [en]

    Today most universities are using course evaluations. However, course evaluations are often discussed and questioned. This paper reports on a survey where we aim at finding out (1) if students have a preconceived notion of a course, (2) if course evaluation scores can be predicted early in a course, (3) if exam throughput impacts course evaluation, and (4) if web-based evaluation reflects the general opinion from students. The results from the study indicate that students do not let preconceived notion impact nor does exam throughput matter to course evaluation. Further, the final web-based results seem to correlate with opinion of students attending lectures. However, the evaluation grades tend to be defined early in the course; hence first impression lasts.

  • 18.
    Mathiason, Gunnar
    et al.
    University of Skövde.
    Amirijoo, Mehdi
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Real-time communication through a distributed resource reservation approach2004Report (Other (popular science, discussion, etc.))
  • 19.
    Tesanovic, Aleksandra
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Amirijoo, Mehdi
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Björk, Mikael
    Hansson, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Empowering Configurable QoS Management in Real-Time Systems2005In: Proceedings of the Fourth ACM SIG International Conference on Aspect-Oriented Software Development AOSD05,2005, USA: ACM Press , 2005Conference paper (Refereed)
    Abstract [en]

    Current Quality of Service (QoS) management methods in real-time systems using feedback control loop lack support for configurability and reusability as they cannot be configured for a target application or reused across different applications. In this paper we present a method for developing reconfigurable feedback-based QoS management for real-time systems, denoted Re-QoS. By combining component-based design with aspect-oriented software development Re-QoS enables successful handling of crosscutting nature of QoS policies, as well as evolutionary design of real-time systems and QoS management architectures. Re-QoS defines a QoS aspect package, which is an implementation of a set of aspects and components that provide a number of different QoS policies. By adding a QoS aspect package to an existing system without QoS guarantees, we are able to use the same system in unpredictable environments where performance guarantees are essential. Furthermore, by exchanging aspects within the QoS aspect package one can efficiently tailor the QoS management of a real-time system based on the application requirements. We demonstrate the usefulness of the concept on a case study of an embedded real-time database system, called COMET. Using the COMET example we show how a real-time database system can be adapted to be used in different applications with distinct QoS needs.

  • 20.
    Tesanovic, Aleksandra
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Amirijoo, Mehdi
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Providing configurable QoS management in real-time systems with QoS aspect packages2006In: Transactions on Aspect-Oriented Software Development II / [ed] Awais Rashid and Mehmet Aksit, Springer Berlin/Heidelberg, 2006, Vol. 4242, p. 256-288Chapter in book (Refereed)
    Abstract [en]

    Current quality of service (QoS) management approaches in real-time systems lack support for configurability and reusability as they cannot be configured for a target application or reused across many applications. In this paper we present the concept of a QoS aspect package that enables developing configurable QoS management for real-time systems. A QoS aspect package represents both the specification and the implementation of a set of aspects and components that provide a number of QoS policies. A QoS aspect package enables upgrades of already existing systems to support QoS performance assurance by adding aspects and components from the package. Furthermore, a family of real-time systems can easily be developed by adding aspects from the QoS aspect package into an existing system configuration. We illustrate the way a family of real-time database systems is developed using the QoS aspect package with a case study of an embedded real-time database system, called COMET. Our experiments with the COMET database have shown that it is indeed possible to design a real-time system without QoS management and then with a reasonable effort add the QoS dimension to the system using a QoS aspect package.

  • 21.
    Tesanovic, Aleksandra
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Amirijoo, Mehdi
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Nilsson, Daniel
    Institutionen för datavetenskap Linköpings universitet.
    Norin, Henrik
    Institutionen för datavetenskap Linköpings universitet.
    Hansson, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Dynamically Reconfigurable QoS-aware Embedded Systems2007In: Embedded Systems: Status and Perspective / [ed] Raj Kamal, USA: American Scientific Publisher , 2007, 2, p. -633Chapter in book (Other academic)
    Abstract [en]

    This book, equally applicable for a CSE or ECE course, gives an extensive account of Embedded Systems, keeping a balanced coverage of hardware and software concepts. Adhering to syllabus needs, this title is ‘microprocessor’ and ‘software design methodology’ specific, giving due weightage to architecture, programming and design aspects.

  • 22.
    Tesanovic, Aleksandra
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Amirijoo, Mehdi
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Nilsson, Daniel
    Norin, Henrik
    Hansson, Jörgen
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Ensuring Real-Time Performance Guarantees in Dynamically Reconfigurable Embedded Systems2005In: IFIP International Conference on Embedded And Ubiquitous Computing EUC,2005, Heidelberg: Springer Verlag , 2005, p. 131-Conference paper (Refereed)
    Abstract [en]

    In this paper we present a quality of service (QoS) adaptive framework for dynamic reconfiguration of component-based real-time systems. Our framework is light-weighted enabling reconfiguration in resource constrained embedded environments. Furthermore, it is possible to reconfigure both components and aspects of a system, hence, enabling finer tuning of a real-time system. Real-time QoS guarantees are maintained in the system and under reconfiguration by employing feedback-based scheduling methods.

  • 23.
    Tesanovic, Aleksandra
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Amirijoo, Mehdi
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nilsson, Daniel
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Norin, Henrik
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Hansson, Jörgen
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Ensuring real-time performance guarantees in dynamically reconfigurable embedded systems2005In: Embedded and Ubiquitous Computing – EUC 2005: International Conference EUC 2005, Nagasaki, Japan, December 6-9, 2005. Proceedings / [ed] Laurence T. Yang, Makoto Amamiya, Zhen Liu, Minyi Guo and Franz J. Rammig, Springer Berlin/Heidelberg, 2005, Vol. 3824, p. 131-141Chapter in book (Refereed)
    Abstract [en]

    In this paper we present a quality of service (QoS) adaptive framework for dynamic reconfiguration of component-based realtime systems. Our framework is light-weighted enabling reconfiguration in resource constrained embedded environments. Furthermore, it is possible to reconfigure both components and aspects of a system, hence, enabling finer timing of a real-time system. Real-time QoS guarantees are maintained in the system and under reconfiguration by employing feedback-based scheduling methods.

  • 24.
    Zhao, Yuxin
    et al.
    Ericsson Research, Linköping, Sweden.
    Yin, Feng
    Ericsson Research, Linköping, Sweden.
    Gunnarsson, Fredrik
    Ericsson Research, Linköping, Sweden.
    Amirijoo, Mehdi
    Ericsson Research, Linköping, Sweden.
    Hendeby, Gustaf
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning2016In: 2016 IEEE 83rd Vehicular Technology Conference (VTC Spring), IEEE , 2016, p. 1-5Conference paper (Refereed)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider network-based positioning based on times series of proximity reports from a mobile device, either only a proximity indicator, or a vector of RSS from observed nodes. Such positioning corresponds to a latent and nonlinear observation model. To address these problems, we combine two powerful tools, namely particle filtering and Gaussian process regression (GPR) for radio signal propagation modeling. The latter also provides some insights into the spatial correlation of the radio propagation in the considered area. Radio propagation modeling and positioning performance are evaluated in a typical office area with Bluetooth-Low-Energy (BLE) beacons deployed for proximity detection and reports. Results show that the positioning accuracy can be improved by using GPR.

1 - 24 of 24
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf