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  • 1. Arlos, Patrik
    Application Level Measurement2011Ingår i: Network Performance Engineering: A Handbook on Convergent Multi-Service Networks and Next Generation Internet, Berlin / Heidelberg: Springer , 2011, s. 14-36Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    In some cases, application-level measurements can be the only way for an application to get an understanding about the performance offered by the underlying network(s). It can also be that an application-level measurement is the only practical solution to verify the availability of a particular service. Hence, as more and more applications perform measurements of various networks; be that fixed or mobile, it is crucial to understand the context in which the application level measurements operate their capabilities and limitations. To this end in this paper we discuss some of the fundamentals of computer network performance measurements and in particular the key aspects to consider when using application level measurements to estimate network performance properties.

  • 2.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    On the Quality of Computer Network Measurements2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Datornät används i mer och mer i vårt dagliga liv, de används för att telefonera, läsa tidningar, se på TV, handla, boka resor etc. På grund av denna diversiteten bland tjänsterna så har mätningar blivit populära under senare år. Detta då de förser nätverksforskningen, utvecklingen och driften med data som används för trafik modellering, prestanda och trend analys. Kvaliteten på dessa mätningar kommer därför direkt påverka resultaten av dessa aktiviteter och därför vår uppfattning av nätverket och dess tjänster. I denna avhandling ger vi en systematisk översikt av datornätverks mätningar och en omfattande översikt av de faktorer som påverkar kvaliteten av prestanda parametrar som tas fram via mätningar. Detta görs genom ett nytt ramverks som beskriver de fyra moduler som påverkar mätningarnas kvalitet: generering, mätning, analys och visualisering. En av de stora källorna till kvalitets problem är noggrannheten på tidstämplar. Dessa tidstämplar beskriver när händelser skedde i nätverket. På grund av detta så presenterar vi en metod som kan uppskatta den tidstämpling noggrannhet som man kan få från mätverktyg, både hård och mjukvara. Metoden används för att utvärdera noggrannheten på några vanliga verktyg, två hårdvarubaserade system (Agilent J6800/J6830A och Endace DAG 3.5E) samt mjukvarubaserade system (Packet Capture Library). Vidare så diskuteras påverkan som analysen har på kvaliteten, och ett exempel ges på hur ett prestanda mått (bitrate) påverkas av mätsystem (hård/mjukvara) och analys metod. Avhandlingen innehåller dessutom utvärderingar av trafik generatorer, applikations mätningar och kvaliteten på mättningar gjorda med PING och J-OWAMP. Huvudslutsatsen i arbetet är att mätsystem och verktyg måste kalibreras, verifieras och valideras innan de används. Baserat på detta så presenterar vi en riktlinje över hur man gör detta.

  • 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. 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.

  • 9. 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.

  • 10. 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.

  • 11. Fiedler, Markus
    et al.
    Arlos, Patrik
    Gonsalves, Timothy A.
    Bhardwaj, Anuraag
    Nottehed, Hans
    Time is perception is money: web response times in mobile networks with application to Quality of Experience2011Ingår i: Lecture Notes in Computer Science, Springer , 2011, Vol. 6821, s. 179-190Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Pappret kvantifierar TCP:s accelerationsbeteende i mobila nät på ett enkelt sätt och relaterar detta till upplevd tjänstekvalité genom enkla formler.

  • 12. Fiedler, Markus
    et al.
    Blouin, Francois
    Arlos, Patrik
    18th ITC Specialist Seminar on Quality of Experience2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The notion and topic of Quality of Experience (QoE) keeps attracting the attention of manufacturers, operators and researchers. It links user perception and expectations on one side and technical Quality of Service (QoS) parameters, management, pricing schemes etc. on the other side. Such links are needed in order to balance user satisfaction and economic aspects of service provisioning. However, the notion of QoE as such is not without controversy. Technicians, used to a world of objective and clearly definable parameters, tend to fear the subjective, somehow fuzzy parts associated with end user perception. Vice versa, customer relationship and marketing departments might find themselves uncomfortable with technical parameters which might not reflect the user perception in some tense situations. Nevertheless, appearance and utility of a networked service depend on the underlying technical solutions and their performance. Thus, we face the challenge of bringing it all together, which essentially describes the spirit of the 18th ITC Specialists Seminar on Quality of Experience (ITC-SS 18). ITC Specialist Seminars have a very good reputation in gathering experts and their high-quality contributions around a performance-oriented topic of mutual interest. ITC-SS 18 is intended as a meeting place between experts, researchers, practitioners, vendors and customers. It is devoted to presentations and discussions of QoE concepts, analysis, management approaches etc., both from industry and academia. While many conferences are dominated by academia, one third of the submissions to ITC-SS 18 originated from industry. The contributions have been peer-reviewed by at least three independent reviewers and finally, we selected 18 papers to be presented. Additionally, two keynote speeches reflect one industrial and one academic approach to QoE analysis and implementation. For the ITC, the leading conference for performance modeling and analysis of communication networks & systems, ITC-SS 18 opens a window towards the end user. ITC-SS 18 takes place in Karlskrona on May 29—30, 2008. It is organized by the Dept. of Telecommunication Systems (ATS) within the School of Engineering (TEK) at Blekinge Institute of Technology (BTH) in cooperation with the International Advisory Council (IAC) of ITC.

  • 13. Fiedler, Markus
    et al.
    Hlavacs, Helmut
    Hackbarth, Klaus
    Arlos, Patrik
    Quality of experience. 1- Metrics and performance evaluation2010Ingår i: Annales des télécommunications, ISSN 0003-4347, E-ISSN 1958-9395, Vol. 65, nr 1-2, s. 1-2Artikel i tidskrift (Refereegranskat)
  • 14. Fiedler, Markus
    et al.
    Hlavacs, Helmut
    Hackbarth, Klaus
    Arlos, Patrik
    Quality of experience 2: Socio-economic aspects2010Ingår i: Annales des télécommunications, ISSN 0003-4347, E-ISSN 1958-9395, Vol. 65, nr 3-4, s. 1-2Artikel i tidskrift (Refereegranskat)
  • 15.
    Fiedler, Markus
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Wac, Katarzyna
    Bults, Richard
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Estimating performance of mobile services from comparative output-input analysis of end-to-end throughput2013Ingår i: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 12, nr 9, s. 1761-1773Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mobile devices with ever-increasing functionality and the ubiquitous availability of wireless communication networks are driving forces behind innovative mobile applications enriching our daily life. One of the performance measures for a successful application deployment is the ability to support application-data flows by heterogeneous networks within certain delay boundaries. However, the quantitative impact of this measure is unknown and practically infeasible to determine at real-time due to the mobile device resource constraints. We research practical methods for measurement-based performance evaluation of heterogeneous data communication networks that support mobile application-data flows. We apply the lightweight Comparative Output-Input Analysis (COIA) method estimating an additional delay based on an observation interval of interest (e.g., one second) induced on the flow. An additional delay is the amount of delay that exceeds non-avoidable, minimal end-to-end delay caused by the networks propagation, serialization and transmission. We propose five COIA methods to estimate additional delay and we validate their accuracy with measurements obtained from the existing healthcare and multimedia streaming applications. Despite their simplicity, our methods prove to be accurate in relation to an observation interval of interest, and robust under a variety of network conditions. The methods offer novel insights into application-data delays with regards to the performance of heterogeneous data communication networks.

  • 16.
    Fiedler, Markus
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    QoE-based Cross-Layer Design of Mobile Video Systems: Challenges and Concepts2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    This conceptual paper focuses on revealing challenges and offering concepts associated with the incorporation of the Quality of Experience (QoE) paradigm into the design of mobile video systems. The corresponding design framework combines application, middleware and networking layer in a unique cross-layer approach, in which all layers shall jointly analyse the quality of the video and its delivery in face of volatile conditions. Particular ingredients of the framework are efficient video processing, advanced realtime scheduling, and reduced-reference metrics on application and network layer.

  • 17.
    Ickin, Selim
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Wac, Katarzyna
    Arlos, Patrik
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Temiz, Canberk
    Mkocha, Khadija
    VLQoE: Video QoE instrumentation on the smartphone2015Ingår i: Multimedia tools and applications, ISSN 1380-7501, E-ISSN 1573-7721, Vol. 74, nr 2, s. 381-411Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The usage of network-demanding applications is growing rapidly such as video streaming on mobile terminals. However, network and/or service providers might not guarantee the perceived quality for video streaming that demands high packet transmission rate. In order to satisfy the user expectations and to minimize user churn, it is important for network operators to infer the end-user perceived quality in video streaming. Today, the most reliable method to obtain end-user perceived quality is through subjective tests, and the preferred location is the user interface as it is the closest point of application to the end-user. The end-user perceived quality on video streaming is highly influenced by occasional freezes; technically the extraordinary time gaps between two consecutive pictures that are displayed to the user, i.e., high inter-picture time. In this paper, we present a QoE instrumentation for video streaming, VLQoE. We added functionality to the VLC player to record a set of metrics from the user interface, application-level, network-level, and from the available sensors of the device. To the best of our knowledge, VLQoE is the first tool of its kind that can be used in user experiments for video streaming. By using the tool, we present a two state model based on the inter-picture time, for the HTTP- and RTSP-based video streaming via 3.5G. Next, we studied the influence of inter-picture time on the user perceived quality through out a user study. We investigated the minimum user perceived inter-picture time, and the user response time.

  • 18. Minhas, Tahir Nawaz
    et al.
    Fiedler, Markus
    Arlos, Patrik
    Quantification of Packet Delay Variation through the Coefficient of Throughput Variation2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Packet delay variation plays an important role in network performance degradation and affects the user-perceptual quality, especially in case of real-time services such as video streaming, VoIP etc. Lightweight methods for detecting network performance issues are desirable as compared to taskintensive measurement and analysis. On this background, this paper discusses the applicability of the Coefficient of Throughput Variation (CoTV) to quickly and reliably detect bottleneck behavior between two arbitrary points in a network. The CoTV can be used as a Reduced Reference Metric. It is relatively simple to calculate, compare and interpret, yet powerful to provide control feedback when facing changes in network performance. In this paper, we demonstrate above mentioned properties of the CoTV through a formula relating it to the sample interval of the throughput and the variability of the delay. The latter is shown to be detectable on time scales that are significantly larger than that of the variability itself. This observation is a key enabler for reducing the load on the device that performs the analysis due to the possibility to use large sample intervals. We also describe how difference and ratio of CoTV at outlet and inlet can be used to identify network performance issues.

  • 19.
    Minhas, Tahir Nawaz
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Shaikh, Junaid
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Evaluation of throughput performance of traffic shapers2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traffic shapers are used by researchers to emulate the behavior of networks and applications in test environments, typically with user-defined traffic shaping parameters such as throughput and loss. Also, traffic shapers are used for the enforcement of SLA, so they are of interest for Internet Service Providers. However, output given by traffic shapers may not be as accurate as desired. Therefore, it is important to assess the accuracy of the implementation of traffic shapers. In this paper, we evaluate two traffic shapers with regard to the performance of their throughput shaping. For this evaluation, traces were collected. The properties of the resulting throughput at the outlet of the shaper are compared to the properties of the throughput at the inlet in combination with the preset shaper parameters. In this sense, we also compare shapers installed on Advance Micro Devices (AMD) and Intel platforms, and we use different PDU sizes and load levels to test the influence of those parameters on the shaping. We are furthermore able to deduct internal shaper parameters such as packet rate and buffer size from our measurements, and we analyse the statistical properties of the packet departure process. The extensive measurement results in this paper allow for a detailed assessment of the question whether the shaper performance is up to mark for a desired timescale. In general, the performance of both shapers and hardware platforms can be considered satisfactory on the investigated time scales between 1 ms and 1 s, with a slight advantage for NetEm on AMD.

  • 20.
    Minhas, Tahir Nawaz
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Lagunas, Oziel Gonzales
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Mobile video sensitivity to packet loss and packet delay variation in terms of QoE2012Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Pappret beskriver sammanhang mellan förluster / fördröjningsvariation och s k "Quality of Experience", och visar dessutom att terminalen (bärbar dator eller smartphone) inte spelar någon särskild roll i kvalitetsutvärderingen genom slutanvändare.

  • 21.
    Paladi, Nicolae
    et al.
    Lund University and RISE.
    Svenningsson, Jakob
    RISE.
    Medina, Jorge
    New Jersey Institute of Technology.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Protecting OpenFlow Flow Tables with Intel SGX2019Ingår i: Proceedings of the ACM SIGCOMM 2019 Conference Posters and Demos, Beijing: ACM Publications, 2019, s. 146-147Konferensbidrag (Refereegranskat)
  • 22.
    Phan, Hoc
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Chu, Thi My Chinh
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Zepernick, Hans-Jurgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Packet Loss Priority of Cognitive Radio Networks with Partial Buffer Sharing2015Ingår i: 2015 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE Computer Society, 2015, s. 7646-7652Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we consider the application of partial buffer sharing to an M/G/1/K queueing system for cognitive radio networks (CRNs). It is assumed that the CRN is subject to Nakagami-m. fading. Secondary users are allowed to utilize the licensed radio spectrum of the primary users through underlay spectrum access. A finite buffer at the secondary transmitter is partitioned into two regions, the first region serves both classes of packets while the second region serves only packets of the highest priority class. Therefore, the examined CRN can be modeled as an M/G/1/K queueing system using partial buffer sharing. An embedded Markov chain is applied to analyze the queueing behavior of the system. Utilizing the balance equations and the normalized equation, the equilibrium state distribution of the system at an arbitrary time instant can be found. This outcome is utilized to investigate the impact of queue length, arrival rates, and fading parameters on queueing performance measures such as blocking probability, throughput, mean packet transmission time, channel utilization, mean number of packets in the system, and mean packet waiting time for each class of packets.

  • 23.
    Phan, Hoc
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Chu, Thi My Chinh
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Delay and Throughput Analysis for Opportunistic Decode-and-Forward Relay Networks2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we develop a queueing analysis for opportunistic decode-and-forward (DF) relay networks. It is assumed that the networks undergo Nakagami-m fading and that the external arrival process follows a Poisson distribution. By selecting the best relay according to the opportunistic relaying scheme, the source first transmits its signal to the best relay which then attempts to decode the reception and forwards the output to the destination. It is assumed that each relay operates in full-duplex mode, i.e., it can receive and transmit signals simultaneously. The communication process throughout the network can be modeled as a queueing network which is structured from sub-systems of M/G/1 and G/G/1 queueing stations. We invoke the approximate analysis, so-called method of decomposition, to analyze the performance behavior of the considered relay network. The whole queueing network is broken into separate queues which are then investigated individually. Based on this approach, the end-to-end packet transmission time and throughput of the considered relay network are quantified in comparison with the networks with partial relay selection (PRS).

  • 24.
    Shaikh, Junaid
    et al.
    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.
    Collange, Denis
    Modeling and Analysis of Web Usage and Experience Based on Link-Level Measurements2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet traffic monitoring and analysis have been playing a crucial role in understanding and characterizing user behavior on the web. In particular, ON-OFF models capture the essential phases of user communication with web servers. The OFF phases reflect both deliberate and accidental gaps in the traffic flow. In this paper, we present a passive monitoring and analysis method devised to assist in the identification of such traffic gaps that may result in the degradation of Quality of Experience (QoE). Our first contribution consists in a revised ON-OFF model to cater for OFF times reflecting accidental gaps which are induced by the network. Second, a wavelet-based criterion is proposed to differentiate between the network-induced traffic gaps and user think times. The proposed method is intended to be implemented in near-real-time as it does not require any deep packet inspection. Both web service providers and network operators may use this method to obtain objective evidence of the appearance of QoE problems from link-level measurements.

  • 25.
    Shaikh, Junaid
    et al.
    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.
    Collange, Denis
    On the Use of TCP Interruptions to Assess User Experience on Web2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Quality of Experience (QoE) is becoming an increasingly popular research area among the ICT related industry and academia.There is a need of a user-centric approach for the design and monitoring of network applications and services. It stimulates the need for an online passive mechanism to monitor the user activity in real-time. The mechanism may vary with the type of application. In this work, we keep our focus on Web browsing application as it is one of the most popular applications on the Internet. The aim is to let the users browse freely and monitor their activity instead of asking them subjectively about their usage experience. Monitoring of the TCP connection interruptions could be one of the ways to have indications about users’ feelings on the Web. This is based on the idea that, in case of bad performance, users break a Web browsing session by pressing a reset or stop button in the browser hence generating a TCP reset on TCP flow level. In this present work, we carry this analysis further to observe the user interruptions in relation to transfer sizes and durations. We want to see how the users react to bad performance and try to explain why we observe smaller mean transfer sizes. Do the users avoid launching large transfers in the case of bad performance or do they try to get the same files but stop the transfers that are becoming too long?

  • 26.
    Shaikh, Junaid
    et al.
    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.
    Minhas, Tahir Nawaz
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Collange, Denis
    Classification of TCP Connection Termination Behaviors for Mobile Web2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many emerging smart applications and services employ Web technology, and users nowadays surf the Web from any device via any kind of access network. Typically, high page latencies trigger users to abort ongoing transfers, resulting in the abrupt terminations of the TCP connections. This paper presents a systematic study of the termination process of the TCP connections and identifies the reasons behind the observed sequences of termination flags. Monitoring and classification of the termination behavior of the TCP connections can provide indications about the user-perceived performance of Web transfers. From the results, it is observed that the TCP termination behavior is heavily-dependent on the client-side application. Therefore, a set of criteria is required to identify the abortions made by the user.

  • 27.
    Shaikh, Junaid
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Minhas, Tahir Nawaz
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Collange, Denis
    Inferring User-perceived Performance of Network by Monitoring TCP Interruptions2012Ingår i: Network Protocols and Algorithms, ISSN 1943-3581, E-ISSN 1943-3581, Vol. 4, nr 2, s. 49-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The fluctuating performance of wireless and mobile networks has triggered the need for smart algorithms to assess the user perception, resulting from the quality of network services. While efforts have been done to model the user experience resulting from the network performance, there is still the need for practical methods to assess the user-perceived performance, in the real environment. In this work, we present a set of criteria to observe the user behavior on the Web, passively from the network-level. The criteria are based on the monitoring of TCP control flags and HTTP requests. Thus, information about user actions performed in the web browser can be inferred by monitoring the TCP termination flags and by keeping track of the HTTP requests. Along the way, we also present some anomalies observed in the TCP connection termination process, which may result in performance degradation of Web transfers.

  • 28.
    Shaikh, Junaid
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Minhas, Tahir Nawaz
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Collange, Denis
    Passive Methods for the Assessment of User-perceived Quality of Delivery2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Passive monitoring of user-perceived performance degradation is an important tool for service providers to improve customer loyalty. In this paper, we discuss our on-going work on the development of two network-based methods to objectively assess the user-perceived network performance. One method is based on the observation of TCP connections interrupted by the users. This method allows us to detect user’s interest in the service in relation to the network performance. Another method is simple and based on the identification of traffic gaps in the user transfers that may hurt the user perception. This work, amongst others, provokes a discussion on the impact of the frequency and duration of such gaps.

  • 29.
    Shaikh, Junaid
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Minhas, Tahir Nawaz
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Evaluation of delay performance of traffic shapers2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In network emulation, traffic shapers are used to shape the performance of the network. They are provided with certain inputs in a test environment to vary the network performance accordingly in order to investigate the effects of different network conditions on applications in real yet emulated scenarios. However, it is very important for the shapers to work as supposed in order to successfully realize the desired network conditions. They may make the results of network emulations unrealistic and unreliable if their functioning is not according to the desired specification. In this work, we evaluate the delay shaping of three traffic shapers, NIST Net, Netem and KauNet through the results obtained from a number of experiments. A comparison of the output of their delay shaping is presented. This comparison can enable us to select the most suitable shaper based on the required shaping. Effects of hardware platforms on the shaping are also filtered out by performing the experiments with shapers installed on Advance Micro Devices (AMD) and Intel platforms separately. Different Protocol Data Unit (PDU) sizes are used in the experiments to test the influence of packet sizes on the shaping. These delay evaluation results are then complemented by the Coefficient of Throughput Variation (CoTV) results.

  • 30. Wac, Katarzyna
    et al.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Chevul, Stefan
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Isaksson, Lennart
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Bults, Richard
    Accuracy Evaluation of Application-level Performance Measurements2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    In many cases, application-level measurements can be the only way for an application to evaluate and adapt to the performance offered by the underlying networks. Applications perceive heterogeneous networking environments spanning over multiple administrative domains as black boxes being inaccessible for lower-level measurement instrumentation. However, application-level measurements can be inaccurate and differ significantly from the lower-level ones, amongst others due to the influence of the protocol stacks. In this paper we quantify and discuss such differences using the DPMI, with Measurement Points instrumented with DAG 3.5E cards for reference link-level measurements. We shed light on various impacts on timestamp accuracy of application-level measurements. Moreover, we quantify the accuracy of generating traffic with constant inter-packet-time. The latter is essential for an accurate emulation of application-level streaming traffic and thus for obtaining realistic end-to-end performance measurements.

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