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  • 1.
    Ammar, Doreid
    et al.
    Norwegian Univ Sci & Technol, NOR.
    De Moor, Katrien
    Norwegian Univ Sci & Technol, NOR.
    Xie, Min
    Next Generat Serv, Telenor Res, NOR.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Heegaard, Poul
    Norwegian Univ Sci & Technol, NOR.
    Video QoE Killer and Performance Statistics in WebRTC-based Video Communication2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we investigate session-related performance statistics of a Web-based Real-Time Communication (WebRTC) application called appear. in. We explore the characteristics of these statistics and explore how they may relate to users' Quality of Experience (QoE). More concretely, we have run a series of tests involving two parties and according to different test scenarios, and collected real-time session statistics by means of Google Chrome's WebRTC-internals tool. Despite the fact that the Chrome statistics have a number of limitations, our observations indicate that they are useful for QoE research when these limitations are known and carefully handled when performing post-processing analysis. The results from our initial tests show that a combination of performance indicators measured at the sender's and receiver's end may help to identify severe video freezes (being an important QoE killer) in the context of WebRTC-based video communication. In this paper the performance indicators used are significant drops in data rate, non-zero packet loss ratios, non-zero PLI values, and non-zero bucket delay.

  • 2. Arkoulis, Stamatios
    et al.
    Marias, Giannis
    Frangoudis, Pantelis
    Oberender, Jens
    Popescu, Alexandru
    Fiedler, Markus
    Meer, Hermann de
    Polyzos, George
    Misbehaviour Scenarios in Cognitive Radio Networks2010Ingår i: Future Internet, ISSN 1999-5903, E-ISSN 1999-5903, Vol. 2, nr 3-4, s. 212-237Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Recent advances in the fields of Cognitive Radio and the proliferation of open spectrum access promise that spectrum-agile wireless communication will be widespread in the near future, and will bring significant flexibility and potential utility improvements for end users. With spectrum efficiency being a key objective, most relevant research focuses on smart coexistence mechanisms. However, wireless nodes may behave selfishly and should be considered as rational autonomous entities. Selfishness, pure malice or even faulty equipment can lead to behavior that does not conform to sharing protocols and etiquette. Thus, there is a need to secure spectrum sharing mechanisms against attacks in the various phases of the sharing process. Identifying these attacks and possible countermeasures is the focus of this work.

  • 3.
    Arlos, Patrik
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    A Method to Estimate the Timestamp Accuracy of Measurement Hardware and Software Tools2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to the complex diversity of contemporary Internet applications, computer network measurements have gained considerable interest during the recent years. Since they supply network research, development and operations with data important for network traffic modelling, performance and trend analysis etc., the quality of these measurements affect the results of these activities and thus the perception of the network and its services. One major source of error is the timestamp accuracy obtained from measurement hardware and software. On this background, we present a method that can estimate the timestamp accuracy obtained from measurement hardware and software. The method is used to evaluate the timestamp accuracy of some commonly used measurement hardware and software. Results are presented for the Agilent J6800/J6830A measurement system, the Endace DAG 3.5E card, the Packet Capture Library (PCAP) either with PF_RING or Memory Mapping, and a RAW socket using either the kernel PDU timestamp (ioctl) or the CPU counter (TSC) to obtain timestamps.

  • 4. Arlos, Patrik
    et al.
    Fiedler, Markus
    Influence of the Packet Size on the One-Way Delay in 3G Networks2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    We currently observe a rising interest in mobile broadband, which users expect to perform in a similar way as its fixed counterpart. On the other hand, the capacity allocation process on mobile access links is far less transparent to the user; still, its properties need to be known in order to minimize the impact of the network on application performance. This paper investigates the impact of the packet size on the minimal one-way delay for the uplink in third-generation mobile networks. For interactive and real-time applications such as VoIP, one-way delays are of major importance for user perception; however, they are challenging to measure due to their sensitivity to clock synchronization. Therefore, the paper applies a robust and innovative method to assure the quality of these measurements. Results from measurements from several Swedish mobile operators show that applications can gain significantly in terms of one-way delay from choosing optimal packet sizes. We show that, in certain cases, an increased packet size can improve the one-way delay performance at best by several hundred milliseconds.

  • 5. Arlos, Patrik
    et al.
    Fiedler, Markus
    Influence of the Packet Size on the One-Way Delay on the Down-link in 3G Networks2010Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Vi utvärderar hur OWD i down-link för 3G (WCDMA/HSDPA) nätverk påverkas av paketstorleken. Vi redogör data för tre Svenska operatörer.

  • 6. Arlos, Patrik
    et al.
    Fiedler, Markus
    Nilsson, Arne A.
    A Distributed Passive Measurement Infrastructure2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we describe a distributed passive measurement infrastructure. Its goals are to reduce the cost and configuration effort per measurement. The infrastructure is scalable with regards to link speeds and measurement locations. A prototype is currently deployed at our university and a demo is online at http://inga.its.bth.se/projects/dpmi. The infrastructure differentiates between measurements and the analysis of measurements, this way the actual measurement equipment can focus on the practical issues of packet measurements. By using a modular approach the infrastructure can handle many different capturing devices. The infrastructure can also deal with the security and privacy aspects that might arise during measurements.

  • 7. Arlos, Patrik
    et al.
    Kommalapati, Ravichandra
    Fiedler, Markus
    Evaluation of Protocol Treatment in 3G Networks2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work, we present a systematic study of how the traffic of different transport protocols (UDP, TCP and ICMP) is treated, in three operational Swedish 3G networks. This is done by studying the impact that protocol and packet size have on the one-way-delay (OWD) across the networks. We do this using a special method that allows us to calculate the exact OWD, without having to face the usual clock synchronization problems that are normally associated with OWD calculations. From our results we see that all three protocols are treated similarly by all three operators, when we consider packet sizes that are smaller than 250~bytes and larger than 1100~bytes. We also show that larger packet sizes are given preferential treatment, with both smaller median OWD as well as a smaller standard deviation. It is also clear that, ICMP is given a better performance compared to TCP and UDP.

  • 8.
    Aziz, Hussein Muzahim
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Grahn, Håkan
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Compressing Video Based on Region of Interest2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Real-time video streaming suffer from bandwidth limitation that are unable to handle the high amount of video data. To reduce the amount of data to be streamed, we propose an adaptive technique to crop the important part of the video frames, and drop the part that are outside the important part; this part is called the Region of Interest (ROI). The Sum of Absolute Differences (SAD) is computed to the consecutive video frames on the server side to identify and extract the ROI. The ROI are extracted from the frames that are between reference frames based on three scenarios. The scenarios been designed to position the reference frames in the video frames sequence. Linear interpolation is performed from the reference frames to reconstruct the part that are outside the ROI on the mobile side. We evaluate the proposed approach for the three scenarios by looking at the size of the compressed videos and measure the quality of the videos by using the Mean Opinion Score (MOS). The results show that our technique significantly reduces the amount of data to be streamed over wireless networks with acceptable video quality are provided to the mobile viewers.

  • 9. Aziz, Hussein Muzahim
    et al.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Grahn, Håkan
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Eliminating the Effects of Freezing Frames on User Perceptive by Using a Time Interleaving Technique2012Ingår i: Multimedia Systems, ISSN 0942-4962, E-ISSN 1432-1882, Vol. 18, nr 3, s. 251-262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Streaming video over a wireless network faces several challenges such as high packet error rates, bandwidth variations, and delays, which could have negative effects on the video streaming and the viewer will perceive a frozen picture for certain durations due to loss of frames. In this study, we propose a Time Interleaving Robust Streaming (TIRS) technique to significantly reduce the frozen video problem and provide a satisfactory quality for the mobile viewer. This is done by reordering the streaming video frames as groups of even and odd frames. The objective of streaming the video in this way is to avoid the losses of a sequence of neighbouring frames in case of a long sequence interruption. We evaluate our approach by using a user panel and mean opinion score (MOS) measurements; where the users observe three levels of frame losses. The results show that our technique significantly improves the smoothness of the video on the mobile device in the presence of frame losses, while the transmitted data are only increased by almost 9% (due to reduced time locality).

  • 10. Aziz, Hussein Muzahim
    et al.
    Fiedler, Markus
    Grahn, Håkan
    Lundberg, Lars
    Streaming Video as Space – Divided Sub-Frames over Wireless Networks2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Real time video streaming suffers from lost, delayed, and corrupted frames due to the transmission over error prone channels. As an effect of that, the user may notice a frozen picture in their screen. In this work, we propose a technique to eliminate the frozen video and provide a satisfactory quality to the mobile viewer by splitting the video frames into sub- frames. The multiple descriptions coding (MDC) is used to generate multiple bitstreams based on frame splitting and transmitted over multichannels. We evaluate our approach by using mean opinion score (MOS) measurements. MOS is used to evaluate our scenarios where the users observe three levels of frame losses for real time video streaming. The results show that our technique significantly improves the video smoothness on the mobile device in the presence of frame losses during the transmission.

  • 11.
    Ballesteros, Luis Guillermo Martinez
    et al.
    KTH Royal Inst Technol, Radio Syst Lab RSLab, Stockholm, Sweden..
    Ickin, Selim
    Ericsson Res, Stockholm, Sweden..
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Markendahl, Jan
    KTH Royal Inst Technol, Radio Syst Lab RSLab, Stockholm, Sweden..
    Tollmar, Konrad
    KTH Royal Inst Technol, Radio Syst Lab RSLab, Stockholm, Sweden..
    Wac, Katarzyna
    Univ Copenhagen, DK-1168 Copenhagen, Denmark..
    Energy Saving Approaches for Video Streaming on Smartphone based on QoE Modeling2016Ingår i: 2016 13TH IEEE ANNUAL CONSUMER COMMUNICATIONS & NETWORKING CONFERENCE (CCNC), IEEE Communications Society, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study the influence of video stalling on QoE. We provide QoE models that are obtained in realistic scenarios on the smartphone, and provide energy-saving approaches for smartphone by leveraging the proposed QoE models in relation to energy. Results show that approximately 5J is saved in a 3 minutes video clip with an acceptable Mean Opinion Score (MOS) level when the video frames are skipped. If the video frames are not skipped, then it is suggested to avoid freezes during a video stream as the freezes highly increase the energy waste on the smartphones.

  • 12. Binzenhöfer, Andreas
    et al.
    Tutschku, Kurt
    Graben, Björn auf dem
    Fiedler, Markus
    Arlos, Patrik
    A P2P-based framework for distributed network management2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present a novel framework supporting distributed network management using a self-organizing peer-to-peer overlay network. The overlay consists of several Distributed Network Agents which can perform distributed tests and distributed monitoring for fault and performance management. In that way, the concept is able to overcome disadvantages that come along with a central management unit, like lack of scalability and reliability. So far, little attention has been payed to the quality of service experienced by the end user. Our self-organizing management overlay provides a reliable and scalable basis for distributed tests that incorporate the end user. The use of a distributed, self-organizing software will also reduce capital and operational expenditures of the operator since fewer entities have to be installed and operated.

  • 13. Binzenhöfer, Andreas
    et al.
    Tutschku, Kurt
    Graben, Björn auf dem
    Fiedler, Markus
    Arlos, Patrik
    DNA, a P2P-based framework for distributed network management2005Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Beskriver en ny management infrastruktur för övervakningen av end-till-end tjänstekvalitet.

  • 14. Burakowski, Wojciech
    et al.
    Krieger, Udo R.
    Leibnitz, Kenji
    Beben, Andrzej
    Meo, Michela
    Ors, Tolga
    Garcia-Vidal, Jorge
    Fiedler, Markus
    An overview on activities on wireless networks on the European project COST 2572000Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper summarises the work on wireless networks inside the COST 257 project, entitled “Impact of new services on the architecture and performance of broadband networks” and chaired by Prof. Tran-Gia of the Technical University of Wurzburg (Germany). This project was established for 4 years (1996-2000) and collected the researchers from 16 European countries represented by 32 organisations. Its topics are modelling, performance, network planning and the analysis of present and future wireless systems.

  • 15. Carlsson, Patrik
    et al.
    Constantinescu, Doru
    Popescu, Adrian
    Fiedler, Markus
    Nilsson, Arne A.
    Delay Performance in IP Routers2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    The main goals of the paper are towards an understanding of the delay process in best-effort Internet for both non-congested and congested networks. A dedicated measurement system is re-ported for delay measurements in IP routers, which follows specifications of the IETF RFC 2679. The system is using both passive measurements and active probing. Dedicated application-layer software is used to generate UDP traffic with TCP-like characteristics. Pareto traffic models are used to generate self-similar traffic in the link. The reported results are in the form of several impor-tant statistics regarding processing delay of a router, router delay for a single data flow, router delay for more data flows as well as end-to-end delay for a chain of routers. We confirm results reported earlier about the fact that the delay in IP routers is generally influenced by traffic characteristics, link conditions and, at some extent, details in hardware implementation and different IOS releases. The delay in IP routers usually shows heavy-tailed characteristics. It may also occasionally show extreme values, which are due to improper functioning of the routers.

  • 16. Carlsson, Patrik
    et al.
    Ekberg, Anders
    Fiedler, Markus
    On an Implementation of a Distributed Passive Measurement Infrastructure2003Övrigt (Övrigt vetenskapligt)
    Abstract [en]

    Having access to relevant, up-to-date measurement data is a key issue for network analysis in order to allow for efficient Internet performance monitoring and management. New applications keep appearing; user and protocol behavior keep evolving; traffic mixes and characteristics are continuously changing, which implies that some year old traffic traces may not reflect reality any more. In order to give a holistic view of what is going on in the network, passive measurements have to be carried out at different places simultaneously. Other challenges relate to the simultaneous use of one specific measurement point at a certain location for different measurement processes, and to continuously ongoing measurements needed for capturing long-term traffic behaviors. On this background, this paper proposes a passive measurement infrastructure for a campus backbone, consisting of distributed coordinated measurement points, collected in measurement areas, measurement administration and data management. … The framework is generic with regards to the capturing equipment, ranging from simple PCAP based devices to high-end DAG cards, and dedicated ASICs, in order to promote a large deployment of measurement points. This structure allows for an efficient use of passive monitoring equipment in order to supply researchers and network managers with up-to-date and relevant data.

  • 17. Carlsson, Patrik
    et al.
    Fiedler, Markus
    Multifractal Products of Stochastic Processes: Fluid Flow Analysis2000Konferensbidrag (Refereegranskat)
    Abstract [sv]

    I nätverks trafik så har multifraktala egenskaper uppmätts. Vi skapar processer med dessa egenskaper och använder sedan en fluid flow analys för att få fram prestanda mått.

  • 18. Carlsson, Patrik
    et al.
    Fiedler, Markus
    Nilsson, Arne A.
    Matching Multi-Fractal Process Parameters Against Real Data Traffic2002Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Vi försöker matcha parametrar som hör till processer med multifraktala egenskaper. Vi försöker matcha mot verklig trafik.

  • 19. Carlsson, Patrik
    et al.
    Fiedler, Markus
    Nilsson, Arne A.
    Modelling of Ethernet Traffic on Multiple Timescales2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ethernet is one of the most common link layer technologies, used in local area networks, wireless networks and wide area networks. There is however a lack of traffic models for Ethernet that is usable in performance analysis. In this paper we use such a model. The model operates on matching multiple moments of the bit rate at several timescales. In order to match the model parameters to measured traffic, five methods have been developed. We use this to model three different links; the BCpOct89 Bellcore trace, an Internet access link and an ADSL link. Our results show that, as the number of sources present on an Ethernet link grows, the model becomes better and less complex.

  • 20. Carlsson, Patrik
    et al.
    Fiedler, Markus
    Tutschku, Kurt
    Chevul, Stefan
    Nilsson, Arne A.
    Obtaining Reliable Bit Rate Measurements in SNMP-Managed Networks2002Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Vi undersöker vilka problem som kan finnas när man använder SNMP för att mäta prestanda i ett nätverk.

  • 21. Chevul, Stefan
    et al.
    Isaksson, Lennart
    Fiedler, Markus
    Karlsson, Johan
    Lindberg, Peter
    Measurement of application-perceived throughput of an E2E VPN connection using a GPRS network2005Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Vi identifierar orsaker varför VPN fungerar dåligt via GPRS

  • 22. Chevul, Stefan
    et al.
    Karlsson, Johan
    Isaksson, Lennart
    Fiedler, Markus
    Lindberg, Peter
    Strandén, Lars
    Measurements of Application-Perceived Throughput in DAB, GPRS, UMTS and WLAN Environments2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Communication services are expected to deliver the desired information in a timely manner without challenging the user’s patience. The corresponding offers by networks are reflected in user- or applications-perceived throughput, which is measured end-to-end for different mobile and wireless networks, namely Digital Audio Broadcast (DAB), General Packet Radio Service (GPRS), Universal Mobile Telecommunication Systems (UMTS), and Wireless Local Area Networks (WLAN). The measurements are based on passive monitoring of throughput statistics for active test traffic and reveal amongst others different kinds of changes of traffic burstiness induced by mobile up- and downlinks and by buffering, respectively. The results will be used for seamless communication, i.e. automatic network selection within the project PIITSA (Personal Information for Intelligent Transport Systems through Seamless communications and Autonomous decisions) aiming at maintaining user-perceived performance and security at the desired levels while keeping communication cost as small as possible.

  • 23. Ciszkowski, Tomasz
    et al.
    Eliasson, Charlott
    Fiedler, Markus
    Kotulski, Zbigniew
    Lupu, Radu
    Mazurczyk, Wojciech
    SecMon: end-to-end quality and security monitoring system2008Ingår i: Annales UMCS Informatica, ISSN 1732-1360, Vol. AI 8, nr 1, s. 185-201Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    Ett system som hjälper att förbättra kvaliten och säkerheten i röstkommunikation via Internet presenteras. Mekanismen bygger på P2P teknik och behöver förhållandevis små resurser. Informationsutbyte sker med hjälp av gömda kanaler. Mer detaljer finns i den engelska versionen.

  • 24. Ciszkowski, Tomasz
    et al.
    Mazurczyk, Wojciech
    Kotulski, Zbigniew
    Hossfeld, Tobias
    Fiedler, Markus
    Collange, Denis
    Towards Quality of Experience-based Reputation Models for Future Web Service Provisioning2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper concerns the applicability of reputations systems for assessing Quality of Experience (QoE) for web services in Future Internet. Reputation systems provide mechanisms to manage subjective opinions in societies and yield general scoring of a particular behavior. Thus, they are likely to become an important ingredient of Future Internet. Parameters being under evaluation by reputation system may vary greatly and, particularly, may be chosen to assess the users’ satisfaction with (composite) web services. Currently, this satisfaction is usually expressed with QoE, which represents subjective users’ opinions. The goal is to predict users’ satisfaction based on reputation values. This may be beneficial for service providers in terms of checking the fulfillment of SLAs, for retaining QoE on the satisfaction level for other users sharing the same network or service resources, and for providing the users with indications which resource to choose in order to maximize its experience.

  • 25. Ciszkowski, Tomasz
    et al.
    Mazurczyk, Wojciech
    Kotulski, Zbigniew
    Hossfeld, Tobias
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Collange, Denis
    Towards Quality of Experience-based reputation models for future web service provisioning2012Ingår i: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 51, nr 4, s. 283-295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper concerns the applicability of reputations systems for assessing Quality of Experience (QoE) for web services in Future Internet. Reputation systems provide mechanisms to manage subjective opinions in societies and yield a general scoring of a particular behavior. Thus, they are likely to become an important ingredient of Future Internet. Parameters being under evaluation by a reputation system may vary greatly and, particularly, may be chosen to assess the users’ satisfaction with (composite) web services. Currently, this satisfaction is usually expressed by QoE, which represents subjective users’ opinions. The goal of this paper it to present a novel framework of web services where a reputation system is incorporated for users satisfaction tracking and prediction. This approach is a beneficial tool, which enables providers to facilitate service adaptation according to users’ expectations and maintain QoE on a satisfying level. Presented reputation system operates in an environment of composite services running on a client and server side. It makes this approach highly suitable for effective QoE differentiating and maximizing user experience for specific customer profiles even the service and network resources are shared.

  • 26. Collange, Denis
    et al.
    Mahdi, Hajji
    Shaikh, Junaid
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    User Impatience and Network Performance2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work, we analyze from passive measurements the correlations between the user-induced interruptions of TCP connections and different end-to-end performance metrics. The aim of this study is to assess the possibility for a network operator to take into account the customers' experience for network monitoring. We first observe that the usual connection-level performance metrics of the interrupted connections are not very different, and sometimes better than those of normal connections. However, the request-level performance metrics show stronger correlations between the interruption rates and the network quality-of-service. Furthermore, we show that the user impatience could also be used to characterize the relative sensitivity of data applications to various network performance metrics.

  • 27. Cousin, Philippe
    et al.
    Fricker, Samuel
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för programvaruteknik.
    Felmy, Dean
    Le Gall, Franck
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Validation and Quality in FI-PPP e-Health Use Case, FI-STAR Project2014Konferensbidrag (Refereegranskat)
  • 28. Dahlberg, Anders
    et al.
    Zepernick, Hans-Jürgen
    Mercankosk, Guven
    Fiedler, Markus
    Multi AP concepts for SCO traffic in a Bluetooth based Radio Infrastructure Network2002Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Bidraget diskuterar möjligheter hur man kan använda Bluetooth för att bygga mobiltelefonliknande nätverk för röstsamtal. Tjänstekvalitén och dimensionering av sådana system diskuteras. Nyckelorden: Bluetooth, accesspunkt, rösttrafik, spärrsannolikhet

  • 29. Dahlberg, Anders
    et al.
    Zepernick, Hans-Jürgen
    Mercankosk, Guven
    Fiedler, Markus
    Multi AP Strategies for SCO Traffic in a Bluetooth based Wireless LAN2003Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Flera Bluetooth enheter i en accesspunkt ger mögligheten att köra flera samtal plus datatrafik samtidigt. Pappret diskuterar olika strategier hur man lägger ut samtal (dvs SCO trafik) på de olika Bluetooth enheter. Bluetooth, Blåtand, accesspunkt, SCO trafik, spärrsannolikhet, dimensionering, signalering, prestanda

  • 30. Duong, Quang Trung
    et al.
    Zepernick, Hans-Jürgen
    Fiedler, Markus
    Cross-Layer Design for Integrated Mobile Multimedia Network with Strict Priority Traffic2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In mobile multimedia networks, different traffic classes require various levels of quality of service (QoS). In this paper, we propose a cross-layer design to provide diverse QoS provisions for integrated realtime/non-realtime traffic by jointly taking into account the physical layer, data link layer, and application layer. Specifically, at the physical layer, adaptive modulation and coding (AMC) is employed to cope with the time-varying nature of fading channels whereas impairments due to queuing effects are considered at the data link layer. At the application layer, realtime and non-realtime traffic are classified into high and low priority classes, respectively, with strict priority levels. The cross-layer scheme is characterized as a discrete Markov modulated Poisson process. Solving the steady state probability of this Markov model readily enables us to investigate several important performance metrics such as packet drop rate due to buffer overflow and packet error rate due to transmission errors and network impairments. Our proposed cross-layer design is verified by comparing the analytical results with Monte-Carlo simulations. Furthermore, it has been shown that the proposed cross-layer design can flexibly guarantee QoS requirements for each traffic class.

  • 31. Duursma, Rick
    et al.
    Fiedler, Markus
    Iterative computations of bit rate summary statistics at inlet and outlet of a discrete time fluid queue2006Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Pappret addresserar ett tidsdiskret flödes-kömodell med fokus på bithastighetsstatistik såsom bithastighetshistogramm och autokorrelation. Flödesmodell, kömodell, tidsdiskret modell, prestandaberäkning

  • 32. Egger, Sebastian
    et al.
    Hossfeld, Tobias
    Schatz, Raimund
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Waiting times in quality of experience for web based services2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    A considerable share of applications such as web or e-mail browsing, online picture viewing and file downloads imply waiting times for their users, which is due to the turn-taking of information requests by the user and correspoding response times until each request is fulfilled. Thus, end-user quality perception in the context of interactive data services is dominated by waiting times; the longer the latter, the less satisfied the user becomes. As opposed to heavily researched multimedia experience, perception of waiting times is still not strongly explored in the context of Quality of Experience (QoE). This tutorial will contribute to closing this gap. In its first part, it addresses perception principles and discusses their applicability towards fundamental relationships between waiting times and resulting QoE. It then investigates to which extent the same relationships can also be used to describe QoE for more complex services such as web browsing. Finally, it discusses applications where waiting times determine QoE, amongst other factors. For example, the past shift from UDP media streaming to TCP media streaming (e.g. youtube.com) has extended the relevance of waiting times also to the domain of online video services. In particular, user-perceived quality suffers from initial delays when applications are launched, as well as from freezes during the delivery of the stream. These aspects, which have to be traded against each other to some extent, will be discussed mainly for HTTP video streaming in the last part of this tutorial.

  • 33.
    Eivazzadeh, Shahryar
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för hälsa.
    Sanmartin Berglund, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för hälsa.
    Larsson, Tobias
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Anderberg, Peter
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för hälsa.
    Most Influential Qualities in Creating Satisfaction Among the Users of Health Information Systems: A Study in Seven EU Countries2018Ingår i: JMIR Medical Informatics, Vol. 6, nr 4, s. 3-21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background:

    Several models suggest how the qualities of a product or service influence user satisfaction. Models, such as the Customer Satisfaction Index (CSI), Technology Acceptance Model (TAM), and Delone and McLean Information Systems Success (D&M IS), demonstrate those relations and have been used in the context of health information systems.

    Objective:

    We want to investigate which qualities foster greater satisfaction among patient and professional users. In addition, we are interested in knowing to what extent improvement in those qualities can explain user satisfaction and if this makes user satisfaction a proxy indicator of those qualities.

    Methods:

    The Unified eValuation using ONtology (UVON) method was utilised to construct an ontology of the required qualities for seven e-health applications being developed in the FI-STAR project, a European Union (EU) project in e-health. The e-health applications were deployed across seven EU countries. The ontology included and unified the required qualities of those systems together with the aspects suggested by the Model for ASsessment of Telemedicine applications (MAST) evaluation framework. Two similar questionnaires, for 87 patient users and 31 health professional users, were elicited from the ontology. In the questionnaires, user was asked if the system has improved the specified qualities and if the user was satisfied with the system. The results were analysed using Kendall correlation coefficients matrices, incorporating the quality and satisfaction aspects. For the next step, two Partial Least Squares Structural Equation Modelling (PLS-SEM) path models were developed using the quality and satisfaction measure variables and the latent construct variables that were suggested by the UVON method.

    Results:

    Most of the quality aspects grouped by the UVON method are highly correlated. Strong correlations in each group suggest that the grouped qualities can be measures which reflect a latent quality construct. The PLS-SEM path analysis for the patients reveals that the effectiveness, safety, and efficiency of treatment provided by the system are the most influential qualities in achieving and predicting user satisfaction. For the professional users, effectiveness and affordability are the most influential. The parameters of the PLS-SEM that are calculated allow for the measurement of a user satisfaction index similar to CSI for similar health information systems.

    Conclusions:

    For both patients and professionals, the effectiveness of systems highly contributes to their satisfaction. Patients care about improvements in safety and efficiency, while professionals care about improvements in the affordability of treatments with health information systems. User satisfaction is reflected more in the users' evaluation of system output and fulfilment of expectations, but slightly less in how far the system is from ideal. Investigating satisfaction scores can be a simple, fast way to infer if the system has improved the abovementioned qualities in treatment and care.

  • 34. Eliasson, Charlott
    et al.
    Fiedler, Markus
    Dimensioning study for road user charging2008Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Vägavgiftslösningar baserade på konceptet med tunna klienter är beroende av tidskorrekta leveranser av positioner för lastbilar till leverantören av vägavgiftssystemet, som sedan utför kartjämförelsen samt uträkningen av vägavgifter. För att undvika dataförluster och sena leveranser måste en ordentlig dimensionering av systemet genomföras, vilket tas upp i denna rapport. Vi undersöker möjligheterna att använda befintliga mobila och trådlösa system (framför allt GPRS, UMTS och WLAN) till både streaming och bulköverföring av positioneringsdata och vi fastställer förnuftiga kombinationer av samplings- och rapporteringsintervall med tanke på effektiv och ekonomisk rapportering. Det valda tillvägagångssättet med erforderlig kapacitet öppnar upp för tolkningar av resursbehoven för de olika kommunikationsteknologierna. Vi framhåller även ett par fällor angående dimensioneringen, framför allt gällande de mönster enligt vilka data skickas, som kan förorsaka överbelastning på serversidan i systemet. Det blir tydligt att mobila nätverk på ett bra sätt kan hantera den belastningen som tillkommer vid rapportering av lastbilar, medan bulköverföring via trådlösa hot-spots kan användas som en komplimenterande lösning. Vägavgiftssystem, dimensionering, GPRS, UMTS, WLAN

  • 35. Eliasson, Charlott
    et al.
    Fiedler, Markus
    Jørstad, Ivar
    A criteria-based evaluation framework for authentication schemes in IMS2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    The IP Multimedia Subsystem (IMS) is regarded as one of the most prominent enablers for successful service provisioning across different access network technologies and devices. While new paradigms, e.g. seamless communication, enter the IMS, existing solutions, e.g. for authentication, need to be redefined, which is one of the major activities within the EUREKA!-funded Mobicome project, involving operators, manufacturers and academia. As there exist several candidate solutions for providing seamless authentication, there is a need for a set of criteria that helps to select the candidate that fulfils those criteria in a bestpossible way. Given this background, this position paper proposes a framework of criteria for the evaluation of authentication schemes in IMS. The primary criteria are security, user-friendliness and simplicity. Inbetween these criteria, the secondary criteria can be found. These are awareness, usability and algorithms. Each criterion, both primary and secondary, is then also divided into one or several substantiating sub-criteria. The discussion of the criteria is followed by a description of the evaluation methodology, which comprises both qualitative and quantitative evaluations such as SWOT analysis, use of NIST and ISO guidelines, user rankings, and measurements of authentication times. The paper is concluded with an outlook on future work, including studies and experiments.

  • 36. Eliasson, Charlott
    et al.
    Fiedler, Markus
    Jørstad, Ivar
    Evaluation of Authentication Schemes Based on Security, User-Friendliness and Complexity2008Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    Ett första ansats för klassificering av sömlösa säkerhetslösningar med tanke på säkerhetsnivå, användarvänlighet och enkelhet som förstahands kriterier samt medvetenhet, användbarhet och algoritmer som andrahands kriterier. Dessutom beskrivs evalueringsmetoder. IMS, säkerhet, sömlös autentifiering, evalueringskriteria

  • 37. Eriksén, Sara
    et al.
    Dittrich, Yvonne
    Fiedler, Markus
    Aurell, Marie
    It Takes More Than Two... Developing a TANGO-Arena for Regional Cooperation around E-government2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    The TANGO e-government arena is an on-going project in Southern Sweden, funded by the Innovative Actions of the European Regional Development Fund. The aim of the project is to establish cooperation between the public sector, private enterprise and university-based research in designing public e-services. Our starting point is e-government understood as co-construction of technology, society and citizenship in everyday life. This approach is based on the Scandinavian Tradition of Participatory Design, but also motivated by on-going technological development. In cooperating around development of new, integrated services, catering to various categories of users as well as to a growing diversity of mobile technologies, we are aiming to establish feedback channels between practice and theory, between use and design, and between different academic disciplines where we see a need to synchronize the models and methods we work with. Our current research questions focus on exploring and managing multi-perspectivity as a resource for design.

  • 38.
    Eriksén, Sara
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för för interaktion och systemdesign.
    Eliasson, Charlott
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Chevul, Stefan
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ekelin, Annelie
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för för interaktion och systemdesign.
    Mapping service quality: measuring and comparing quality of experience and quality of service for Internet-based map services2007Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Presentation av ett pågående forskningsprojekt där fokus ligger på hur man kan mäta användares upplevelser av tjänstekvalitet med både kvalitativa och kvantitativa metoder, för att därmed kunna utveckla mer effektiva metoder för mätning, övervakning och kontroll av tjänstekvalitet för krävande nätverkstjänster. Svenska nyckelord: tjänstekvalitet, upplevelsekvalitet, nyckelvärdesindikatorer, användningsorienterad utveckling, tjänstedesign

  • 39. Erman, David
    et al.
    Fiedler, Markus
    Collaborative Video Streaming in Future Networks: Extended Abstract2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Video streaming and mesh-based peer-to-peer file sharing are two of the most bandwidth-demanding applications in the current Internet. In particular non-popular video streaming is on the increase, and future networks are likely to be even more involved in this type of application. Another expected ma jor defining trait of future network is heterogeneity, not only with respect to access technologies, but also several other factors, such as user mobility and terminal capability. This extended abstract delineates some of the most pressing challenges to be faced by mesh-based collaborative video streaming systems, with particular focus on maintaining adequate Quality of Experience (QoE).

  • 40. Fiedler, Markus
    Direct Evaluation of Required Capacity for ATM Multiplex1998Övrigt (Övrigt vetenskapligt)
    Abstract [sv]

    Ett sätt att räkna ut erforderlig kapacitet för dimensionering av datanätverk presenteras. Tjänstekvalitet, dimensionering, flödesmodell

  • 41. Fiedler, Markus
    Euro-NGI D.JRA.6.1.1: State-of-the-art with regards to user-perceived Quality of Service and quality feedback2004Övrigt (Övrigt vetenskapligt)
    Abstract [sv]

    Denna deliverable presenterar nuläget gällande användareupplevt tjänstekvalitet och kvalitetsåterkoppling, som är titeln på arbetspaketet JRA.6.1 inom Network of Excellence Euro-NGI. Dokumentet innehåller ett överblick kring relaterade standards och status, diskuterar användarens roll och presenterar metoder för att koppla avändareupplevelse till tekniska parametrar. Vidare presenterar dokumentet utvalda bidrag av partners inom detta arbetspaket samt relevanta forskningsfrågor. Tjänstekvalitet, användareupplevelse, kvalitetsåterkoppling

  • 42. Fiedler, Markus
    Formula for the required capacity of an ATM multiplexer1998Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Pappret behandlar snabba beräkningar av kapaciteten i datakom nätverk som behövs för att garantera en önskad kvalitetsnivå. Dessa beräkningar grundas på faltningar av bandbredds statistik. Resursbehov, flödesmodell, kapacitetsberäkningar, faltning

  • 43. Fiedler, Markus
    Generic Network Service Components for Networks of the Future2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    Nätverkskomponenter som delar av framtida tjänster beskrivs generellt, och några exempel av redan existerande nätverksfunktioner ges.

  • 44. Fiedler, Markus
    Internet performance issues for safety-critical applications2004Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Genomgång av prestanda problem samt möjligheten att visualiera dessa t ex med en flaskhalsindikator.

  • 45. Fiedler, Markus
    Modeling and Analysis of Wireless Network Segments with aid of Teletraffic Fluid Flow Models2000Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Inflytandet av kanalkvaliten i ett trådlöst nätsegment på överföringskvaliten på nätverksnivån studeras. Detta sker med hjälp av en (informations-)flödesmodell med tidsvariabelt kapacitet. Resultaten visar att ändringshastigheten av kanalkvaliten innehar ett stort inflytande på kvaliten på nätverksnivan. Dessutom presenterar rapporten ett användarvänligt och numeriskt stabilt mjukvarakoncept for beräkningsverktyget.

  • 46. Fiedler, Markus
    On Resource Sharing and Careful Overbooking for Network Virtualization2009Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Nätverksvirtualisering bygger på resursdelning. Att dela resurser mellan för många användare (dvs för hög överbeläggning) leder till prestandaförluster, medan uteslutandet av potentiella användare är problematiskt med. Pappret undersöker rymliga gränser för överbeläggning med tanke på full eller en väldefinerad del av kapaciteten som användaren behöver.

  • 47. Fiedler, Markus
    On resource sharing and careful overbooking for network virtualization2011Ingår i: International Journal of Communication Networks and Distributed Systems, ISSN 1754-3916, E-ISSN 1754-3924, Vol. 6, nr 3, s. 232-248Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Network Virtualization implies the need for sharing network resources. However, exclusive resource allocation to users drives blocking probabilities and cost while potentially leaving precious resources under-utilized in constrained environments. Motivated by these observations, this paper analyzes careful overbooking according to Service Level Agreements that specify desired degrees of availability. Besides of full availability of the requested resources, a second level of limited availability, implying a well-defined reduction of the allocated resource, is taken into account. Particular attention is paid to the gain borderline, representing the possibility of accommodating one extra user beyond exclusive allocation without violating the SLAs. Simple but telling formulae provide insights into requirements for careful overbooking, worst-case capacity reduction factors from full to limited availability, and the conditions under which it is sensible to integrate users with different activity levels. We also link capacity reductions to potential decreases in Quality of Experience.

  • 48.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    On the Limited Potential of Buffers to Improve Quality of Experience2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates the potential of improving the Quality of Experience (QoE) of pervasive video delivery by buffering. It reveals the importance of delivering video without freezes to the end user. It then introduces a fluid flow model that leads to a closed formula for the freeze probability, and matches measured distributions of on- and off-times to this model's exponential distributions in order to underline its feasibility. The closed formula for the freeze probability is then used to investigate the impact of two buffer size adaptation policies, one additive and one multiplicative with regards to the deviation of the average off-time from its nominal value. It is proven that, besides of some specific conditions in the additive case, the freeze probability grows with the disturbance, which means that even an increased buffer size implies worse performance and thus QoE. It also points out a way out of this dilemma, which is to try to reduce off times by reducing the utilization of the mobile link.

  • 49. Fiedler, Markus
    PERIMETER: Privacy-preserving contract-less, user-centric, seamless roaming for Always Best Connected Future Internet2009Konferensbidrag (Refereegranskat)
    Abstract [sv]

    PERIMETER är ett nytt koncept för framtidens Internet som går ut på att väljer nät att kunden som kommer att bli alltid bäst ansluten oavseende nätverksteknologi. Kunden behöver inte ha många abonnemang. Autentifiering m m hanteras distribuerad av PERIMETER. Framtida Internet, upplevd tjänstekvalitet, alltid bäst anslutet, säkerhet

  • 50. Fiedler, Markus
    Quality feedback flows in future networks2009Ingår i: Elektrotechnik & Informationstechnik, ISSN 0932-383X, Vol. 126, nr 7Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    Pappret identifierar problem med nuvarande mest implicita kvalitetsåterkoppling mellan nätverksoperatörer, tjänsteleverantörer och användare. Det introducerar ett koncept för mer explicit och framtidsinriktad kvalitetsåterkoppling som bygger bl a på självorganierande overlay nätverk.

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