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  • 101. Hossfeld, Tobias
    et al.
    Hock, David
    Tran-Gia, Phuoc
    Tutschku, Kurt
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Testing the IQX Hypothesis for Exponential Interdependency between QoS and QoE of Voice Codecs iLBC and G.7112008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Given the growing importance of quantitative relationships between user-perceived Quality of Experience (QoE) and network Quality of Service (QoS), this paper investigates the IQX hypothesis for two voice codecs, iLBC and G.711. This hypothesis expresses QoE as an exponential function of QoS degradation. The experiments are carried out in a controlled environment using the softphone SJPhone, the network emulator NIST Net, and a tool calculating the PESQ (Perceptual Evaluation of Speech Quality) from sent and received audio files. The IQX hypothesis is confirmed exactly for disturbances perceived on applications level, packet loss and packet reordering, which clearly correlate to the main sensitivities of the used softphone to packet-level disturbances such as loss, jitter and reordering. So, besides of providing a unified relationship between QoE and QoS, the IQX also proved to be capable of identifying the QoS parameters of relevance for QoE degradations. The study also points out interesting tracks for future work in terms of QoS degradations and related QoE evaluations.

  • 102.
    Ickin, Selim
    et al.
    Blekinge Tekniska Högskola.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Quality of Experience on Smartphones: Network, Application, and Energy Perspectives2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For service and mobile operators, it is importantto monitor and keep high user engagement levels. Qualityof Experience (QoE) on video streaming applications is animportant engagement measure for video consumer customers.In this paper, video QoE (with the focus on stalling events)is studied from network, application, and energy perspectiveswith various instrumentations on a smartphone. This enablesthe understanding of inter-relation between the perspectives andalso how they influence the video QoE. Results show that packetdelay variation and the maximal burst size in the network level;inter-picture time (picture delay) in the application layer; andalso fluctuations in the energy consumptions are strong indicatorsfor QoE. We show, via extensive QoE and energy measurementson smartphones that, based on the choice of streaming protocol,energy consumption can be reduced or increased in the case ofstalling events during a video stream.

  • 103.
    Ickin, Selim
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Wac, Katarzyna
    Demonstrating the Stalling Events with Instantaneous Total Power Consumption in Smartphone-based Live Video Streaming2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The smartphone usage nearly tripled 2011 according to Cisco Virtual Networking Index. There is a high demand of energy for using popular mobile applications, which run on smartphones with limited battery life. Video streaming applications are widely used on mobile devices, and their high power consumption exhibits high variance during a live streaming session, due to varying conditions on network and application levels. Recent studies focus on the averaged power consumption statistics, while there is lack of observation on the fluctuations of the instantaneous total power consumption of the smart- phones. Network based applications consume power at all layers of the communication stack, and any fluctuation in the total power consumption during a video streaming can reveal a possible misbehaviour such as a stalling event. Until now, these events are investigated in Quality of Experience (QoE) studies through installation of high-energy demanding and hard-to-deploy network measurement tools on users’ mobile devices. In this paper, we demonstrate an ex- periment, where a user experiences a stalling event on the smartphone and observes the live instantaneous power consumption values through Mobile Power Monitoring Tool (MPMT) and Software Visualisa- tion Tool (SVT), simultaneously. We confer that the instantaneous total power consumption likely reveals the misbehaviours such as stalls during a video play- out in live video streaming on smartphones that can facilitate energy efficient QoE studies.

  • 104.
    Ickin, Selim
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Wac, Katarzyna
    Energy-based Anomaly Detection in Quality of Experience2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Subjective performance of smartphone-based high bandwidth- and energy-demanding applications and services such as video streaming, are highly influenced by the temporal impairments perceived by the user at the user interface; and the application's energy consumption patterns. Therefore, we study the influence of the anomalies detected by objective measurements from the user interface and the network-level, on the power consumption during video streaming on the smartphone. In this paper, we study the inter-frame time metric, i.e., the time gap between two consecutive displayed pictures at the user interface; the inter-packet time and the initial signaling duration at the network-level; and the instantaneous power consumption at the power supply of the smartphone. We conduct experiments on the VLC media player, while streaming video via local-storage; via 3G using RTSP protocol; and via 3G using HTTP protocol. We show that the anomalies detected at the instantaneous power consumption reveals the anomalies at the user interface and the network-level.

  • 105.
    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 smartphone2015Inngår i: Multimedia tools and applications, ISSN 1380-7501, E-ISSN 1573-7721, Vol. 74, nr 2, s. 381-411Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 106.
    Ickin, Selim
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Janowski, Lucjan
    Wac, Katarzyna
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Studying the challenges in assessing the perceived quality of mobile-phone based video2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Evaluating video Quality of Experience (QoE) on a mobile phone has not yet been studied much. It is common that the data collected through user studies in mobile platform involves high fluctuation of user ratings without obvious reasons related to variation in network level. User disparity, user's various intermediate or previous experiences, video bitrate, and the objective measure of criticality are a few of the reasons that need to be identified with a well-designed user experiment. We present an experiment procedure to understand better the perceived quality of video in mobile platform. First, we investigate the reliability of the data, and identify unreliable users. Then, we investigate the psychological influence factors of previous experiences on the recent perceived quality known as the memory effect, and the influence of the bitrate on the time it takes for users to react and evaluate the video quality, i.e., user response time.

  • 107. Ickin, Selim
    et al.
    Vogeleer, Karel De
    Fiedler, Markus
    Erman, David
    On the Choice of Performance Metrics for User-Centric Seamless Communication2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Being connected to a wireless access point is not enough; in addition, adequate per-application performance is expected. To achieve high user perception, it is necessary to adapt the ongoing connection to the frequently changing network conditions. Not only collecting Quality of Service (QoS) metrics but analyzing these on a per-technology basis is vital and so far not questioned much. In particular, for each type of network, a specific performance metric that correlates well with the user ratings can be identified.

  • 108. Ickin, Selim
    et al.
    Vogeleer, Karel De
    Fiedler, Markus
    Erman, David
    The Effects of Packet Delay Variation on the Perceptual Quality of Video2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The satisfaction of end-users is important when evaluating services and products. Visualizing the network behavior in mobile streaming as well as modeling the correlation between Quality of Service (QoS) and Quality of Experience (QoE) is expected to improve user satisfaction of services on the Internet. Given that network and human factors are the elements that affect the final output of the measurements, it is important to take the Packet Delay Variation (PDV) into consideration. In this paper we observe the PDV during a series of real-life experiments on a 3rd Generation (3G) network while streaming videos. User Rating (UR) values from user input are recorded accordingly. With this aim, we implemented a QoE assessment tool that measures network metrics in kernel space, while simultaneously logging user ratings with regards to the perception of an ongoing real- time video on an Android phone. The primary goal is to identify a clear trend, so that we can assess the satisfaction of a user by deriving the QoE from measurable QoS metrics. We find that PDV degrades user perception. Observations show that, during the experiments, sudden breaks and restarts in the packet flow exist, which we call on-off flushing throughout this paper. Even though the use of Exponentially Weighted Moving Average (EWMA) assists in finding a model that shows the relationship between PDV and UR, on-off flushing is a major threat affecting this relationship. The results show that correlations with different quality can be reached with various modifications of the proposed matching model.

  • 109.
    Ickin, Selim
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Wac, Katarzyna
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    QoE-Based Energy Reduction by Controlling the 3G Cellular Data Traffic on the Smartphone2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    One of the most influencing factors on the overall end-user perceived quality from applications and services, i.e., QoE, running on the smartphones is their limited battery life. Particular cloud-based applications/services on the smartphone with a constrained battery life might consume high energy even when the smartphone is in screen-OFF state. The cellular radio module of the smartphone is one of the most power-consuming components, which depends on the running applications' information polling characteristics that eventually cause the radio module to toggle occasionally between the cellular data energy states even during a sleep state. In this paper, we investigate the energy consumption of a set of applications that tend to retain up-to-date information via aggressive polling patterns. We show that limiting the network traffic and increasing the resource utilization efficiency amongst the applications and services can highly reduce the total energy consumption. We control the network activity of a smartphone with different cellular data-enabled and data-disabled durations at the screen-OFF state. First, we run controlled-lab energy measurements to have a ground truth on the power consumption patterns of a set of cloud-based popular applications/services; and next we conduct a subjective study with our proposed solution (ExpCO2), to understand first the user behaviour on the smartphone and then present how the reduced polling intervals of applications and notifications influence the end-user perceived quality. We indicate that ExpCO2 has a potential to save energy.

  • 110.
    Ickin, Selim
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Wac, Katarzyna
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Janowski, Lucjan
    Hong, Jin-Hyuk
    Dey, Anind K.
    Factors influencing quality of experience of commonly-used mobile applications2012Inngår i: IEEE Communications Magazine, ISSN 0163-6804, Vol. 50, nr 4. Special Issue on QoE Man- agement in Emerging Multimedia Services, s. 48-56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increasingly, we use mobile applications and services in our daily life activities, to support our needs for information, communication or leisure. However, user acceptance of a mobile application depends on at least two conditions; the application’s perceived experience and the appropriateness of the application to the user’s context and needs. Yet, we have a weak understanding of a mobile user’s Quality of Experience (QoE) and the factors influencing it. This paper presents 4 week long, 29 Android phone users study, where we collected both QoE and underlying network’s Quality of Service (QoS) measures through a combination of user, application and network data on the user’s phones. We aimed to derive and improve the understanding of users’ QoE for a set of widely used mobile applications in users’ natural environments and different daily context. We present data acquired in the study and discuss implications for mobile applications design.

  • 111.
    Ickin, Selim
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Zinner, Thomas
    Wac, Katarzyna
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Catching the download train: Energy-efficient file downloading on smartphones2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The most energy-consuming applications in battery life-constrained smartphones are the ones that comprise data transmission, especially via the 3G interface. Scheduling download activities on smartphones is especially necessary, if there are multiple asynchronous downloads scattered over a long duration. The latter scenario highly increases the energy consumption of smartphones. In this paper, we investigate energy consumption with the focus on file downloading while scheduling multiple file downloads in two scenarios: serialized and parallel. We repeat the experiments on a single smartphone via its 3G and also via WiFi tethering via another smartphone. We assess the performance of the two scenarios via measurement of power consumption and corresponding download duration in a realistic environment.

  • 112.
    Iqbal, Muhammad Imran
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    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.
    Spatio-Temporal Quality of Experience Trade-offs for Mobile Imaging Applications2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we focus on mobile images given in JPEG2000 format and evaluate their spatio-temporal Quality of Experience (QoE). In particular, the trade-of between spatial QoE supported by progressive source encoding and temporal QoE related to network delay as well as initial transmission delay is examined.

  • 113. Isaksson, Lennart
    et al.
    Chevul, Stefan
    Fiedler, Markus
    Karlsson, Johan
    Lindberg, Peter
    Application-Perceived Throughput Process in Wireless Systems2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Motivated by the central role and the importance of network throughput for the performance of networked applications and thus for user experience, this paper investigates the process of user-perceived throughput. This throughput is measured on rather small time scales and interpreted with aid of summary statistics, histograms and autocorrelation coefficients. The results including GPRS, UMTS and WLAN measurements reveal a clear influence of the network, seen from variations of application-perceived throughput on the one-second time scale, which has to be considered when choosing the right kind of network for a specific task. The different statistical metrics considered will later be used in our research to maintain the QoS of the service decided by the user. While theoretical throughputs are yielded as expected in UMTS, both GPRS and WLAN do not reach the promised throughput values.

  • 114. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Improved Time to Connect for Bluetooth2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Bluetooth has from its beginning used Frequency Hopping (FH) from version 1.0A to the current version 1.2. The so-called selection box uses a complex scheme to calculate the next correct frequency in time. This makes transmissions between Bluetooth devices both robust and secure. Several attempts have been carried out to improve the time to connect, due to the relatively high time to connect given by the Bluetooth specification. Many have not fully understood the FH for Bluetooth and have therefore suggested sub-optimized solutions to improve the time to connect. In this paper, a presentation of the problem that causes the poor time to connect performance is given. This knowledge is needed for an improvement of the time to connect for Bluetooth. To accomplish a reduction of the time to connect by a factor of 100, three main parameters have to be changed: First, the A-train and B-train should be switched directly after each other. Second, the phase should be switched faster, which is based on the clock. Finally, a reduction of the random backoff parameter needs to be considered. These changes, together with other parameters, like time out values, have to be changed/reduced accordingly. Together with these changed parameters a simulation of the time to connect for Bluetooth is presented.

  • 115. Isaksson, Lennart
    et al.
    Fiedler, Markus
    On-Demand Ad Hoc Routing with Modified Reverse Path Forwarding for Bluetooth2004Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In an ad hoc network connection establishment is done to secure a path for routing packets from source to destination. This path is then maintained to secure further transmissions. In the case of Wireless Personal Area Networks (WPAN) which are more flexible, this is not usable. This is especially the case for Bluetooth. Some constraints in Bluetooth demands a more flexible on-demand ad hoc network compared to other types of ad hoc network protocols. Initially we found that creating a scatternet is not practically possible using Bluetooth version 1.1. The slave/slave bridge is not implemented into the hardware to create a scatternet. In this paper, we present a modified version of the Reverse Path Forwarding (RPF) algorithm to make it suitable for Bluetooth routing. With an on-demand ad hoc network solution together with the modified RPF algorithm we present a suitable solution for Bluetooth packets to be routed in a flexible ad hoc network. To be able to test the modified RPF and the on-demand ad hoc network, a test platform has also been developed.

  • 116. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Optimization of the Random Backoff Boundary of the Bluetooth FHSS Technique2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The goal of an ad hoc network is to create a wireless connection when needed between nodes. Regarding Bluetooth (IEEE 802.15.1) the so-called state machine based on the selection box is responsible for the Frequency Hopping (FH). In this state machine a particular sub-state (random backoff) is heavily involved in the time-to-connect between two devices.

  • 117. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Seamless Connectivity in WLAN and Cellular Networks with Multi Criteria Decision Making2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The evolution of today's wireless and mobile technologies and personalized hand-held devices has increased the challenge to handle the trade-off between mobility, performance and cost. The user simply needs to be Always Best Connected (ABC). To make this happen, different types of criteria reflecting relevant characteristics of wireless and mobile access networks such as WLAN, UMTS and GPRS have to be established and judged. In this paper the criteria are divided into three main groups, performance, cost and accessibility. The criteria are fed into a Multi Criteria Decision Making (MCDM) tool which is able to deliver a ranking of network links in order to become ABC. Finally, a case study with two different Generic Services (GS) illustrates the decision making process and its outcomes in different situations.

  • 118. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Nilsson, Arne A.
    Validation of Simulations of Bluetooth's Frequency Hopping Spread Spectrum Technique2004Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The need for performance studies avoiding expensive hardware installations and the lack of analytical models motivates the need of trustworthy simulation models for the cable-replacement technology Bluetooth. In this paper we show a detailed description of the Bluetooth technique and validation of different simulation models used today. To do this, a two-step approach for validation and credibility is necessary. First, a comprehensive empirical measurement was performed to establish a "status quo" of the behavior of today's Bluetooth technology. Second, a validation between empirical and simulation model is conducted to ensure the comparability. To accomplish these objectives we developed and validated a simulation model with frequency hopping algorithms and the whole state machine including collision detection. The results in form of histograms of different Bluetooth-specific durations indicate problems in case of already established simulation programs. So, finally, some changes and suggestions how to correct these defects are given.

  • 119. Isaksson, Lennart
    et al.
    Fiedler, Markus
    Rakus-Andersson, Elisabeth
    A Fuzzy Set Theory Based Method to Discover Transmissions in Wireless Personal Area Networks2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The complexity within a Wireless Personal Area Network (WPAN) increases. Several technologies have to share the same radio spectrum. In this paper we take a look at the 2.4 GHz Industrial Scientific and Medical (ISM)-band. This paper discusses a method of selecting the best wireless channel within Wireless Local Area Network (WLAN) when several technologies could be used in the same WPAN range of the needed access point. The issue is to keep away from already occupied channels. The method is divided into four steps: the passive probing of the power level detecting IEEE 802.15.4 (ZigBee) channels using a new and affordable hardware, the transformation of the probed data to a linguistic level using Fuzzy Set Theory (FST), the classification of the data, and finally the sorting and selection of channels based on whose power levels.

  • 120. Isaksson, Lennart
    et al.
    Johnson, Henric
    Fiedler, Markus
    Toward Seamless Integration of Wireless LAN and Cellular Networks2005Rapport (Annet vitenskapelig)
    Abstract [en]

    Networked applications, no matter whether connected in a wired or wireless way, rely upon the ability of timely data delivery. The achievable throughput is a quality measure for the very task of a communication system, which is to transport data in time. This is of particular importance for nowadays trendy streaming applications such as digital TV, Internet Protocol (IP)-telephony, and gaming. Especially the higher throughput offered by 3G mobile systems (and beyond) as compared to earlier generations of mobile communications seems to pave the way for streaming applications into mobile environments. In this report a method is described that makes a decision between different communication technologies depending on different criteria and expectations stated by the end-user and perceived within the network itself. The Multi-Criteria Decision Making (MCDM) method together with the Analytic Hierarchy Process (AHP) method is used to achieve the concept of Always Best Connected (ABC). Two different groups of criteria are used: benefits and costs. Within the benefit group three metrics are used: Initial Delay (ID), Link Capacity (LC) and Direction Loss (DL) which are analyzed and used before a decision is made. These three metrics are weighted against each other. Finally a case study is presented, using the AHP together with the weighted metrics.

  • 121.
    Islam, Nazrul
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Elepe, Vijaya John David
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Shaikh, Junaid
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    In Small Chunks or All at Once? User Preferences of Network Delays in Web Browsing Sessions2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The time-critical tasks on the Internet are increasing. The delays in these tasks can have severe implications on the Quality of Experience (QoE) of a service. Therefore, networks require smart user-centric resource management mechanisms to reduce the impact of these delays on QoE. For this, a better understanding of the user preferences with regards to service performance is a prerequisite. In this paper, we present user responses to the three different distributions of delays, occurring during shopping sessions on the Web. By keeping the overall waiting time of the sessions same, we show how the users respond differently to the different set of delays. We analyzed the user responses and found that, the users prefer small frequently occurring delays as compared to the long rarely occurring delays within a task-based session.

  • 122. Johnson, Henric
    et al.
    Isaksson, Lennart
    Fiedler, Markus
    Wu, Felix
    A Decision System for Adequate Authentication2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A practical decision system is developed for finding the adequate authentication level based on desirable security criteria and alternatives. Even though the notion of lightweight security is acknowledged, the process of determining when to use it instead of strong security is not well understood. The process of making such a decision can be very complex. By defining an overall security goal and a set of criteria with corresponding alternatives, the Analytic Hierarchy Process (AHP) is used to select the most suitable, preferred (and thus, adequate) authentication level, which is demonstrated by a realistic case study.

  • 123. Johnson, Henric
    et al.
    Nilsson, Arne A.
    Fiedler, Markus
    Wireless Network Security2001Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we describe and give an overview of the various security aspects and problems that have emerged in the area of wireless communications during the last few years. Wireless Application Protocol (WAP), HiperLAN, Bluetooth and wireless LAN standard IEEE 802.11b are central standards of investigation in this paper. In conclusion, we believe that future wireless network systems will probably consist of many different wireless systems linked together, therefore there will be a need for how to harmonize the differences in their security solutions.

  • 124. Johnson, Henric
    et al.
    Qaisrani, Babar
    Fiedler, Markus
    Wu, Felix
    Nilsson, Arne A.
    Analysis of IPSec Performance2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we present the results of an experimental analysis of IPSec performance. IPSec serves as a security service to protect a communication session over unreliable networks using several cryptographic functions. The different IPSec features used to obtain confidentiality, authentication, replay protection, and integrity introduce performance costs brought about by the increased processing overhead. The performance parameters of interest are delay and throughput. However, there is a tradeoff between performance and security. The results of the performance tests indicate the vulnerability of a Denial-of-Service attack against a gateway running IPSec due to resource exhaustion.

  • 125. Johnson, Henric
    et al.
    Qaisrani, Babar
    Fiedler, Markus
    Wu, Felix
    Nilsson, Arne A.
    Hierarchical Defense Structure for Mitigating DoS Attacks2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper provides the contribution of mitigating a Denial-of-Service (DoS) attack via a developed hierarchical defense structure with proactive functionality. An important aspect is the tradeoff between performance and security. This novel hierarchical architecture is presented with lightweight authentication protocols acting as a classifier to deny access to harmful traffic. An empirical test of the proposed structure has been performed and results are reported which display the capability of the structure to filter and separate the attack traffic before reaching the target of an IPSec gateway. Thus, the filtering of traffic is performed without being the target itself for new resource exhaustion attacks. The considered IPSec environment is based on IPSec gateways for the low-end market, i.e., for small businesses or private networks.

  • 126.
    Kelkkanen, Viktor
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    A Test-bed for Studies of Temporal Data Delivery Issues in a TPCAST Wireless Virtual Reality Set-up2018Inngår i: 2018 28TH INTERNATIONAL TELECOMMUNICATION NETWORKS AND APPLICATIONS CONFERENCE (ITNAC), IEEE , 2018, s. 404-406Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Virtual Reality (VR) is becoming increasingly popular, and wireless cable replacements unleash the user of VR Head Mounted Displays (HMD) from the rendering desktop computer. However, the price to pay for additional freedom of movement is a higher sensitivity of the wireless solution to temporal disturbances of both video frame and input traffic delivery, as compared to its wired counterpart. This paper reports on the development of a test-bed to be used for studying temporal delivery issues of both video frames and input traffic in a wireless VR environment, here using TPCAST with a HTC Vive headset. We provide a solution for monitoring and recording of traces of (1) video frame freezes as observed on the wireless VR headset, and (2) input traffic from the headset and hand controls to the rendering computer. So far, the test-bed illustrates the resilience of the underlying WirelesslID technology and TCP connections that carry the input traffic, and will be used in future studies of Quality of Experience (QoE) in wireless desktop VR.

  • 127.
    Kelkkanen, Viktor
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Coefficient of Throughput Variation as Indication of Playback Freezes in Streamed Omnidirectional Videos2018Inngår i: 2018 28TH INTERNATIONAL TELECOMMUNICATION NETWORKS AND APPLICATIONS CONFERENCE (ITNAC), IEEE , 2018, s. 392-397Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A large portion of today's network traffic consists of streamed video of large variety, such as films, television shows, live-streamed games and recently omnidirectional videos. A common way of delivering video is by using Dynamic Adaptive Streaming over HTTP (DASH), or recently with encrypted HTTPS. Encrypted video streams disable the use of Quality of Service (QoS) systems that rely on knowledge of application-dependent data, such as video resolution and bit-rate. This could make it difficult for a party providing bandwidth to efficiently allocate resources and estimate customer satisfaction. An application-independent way of measuring video stream quality could be of interest for such a party. In this paper, we investigate encrypted streaming of omni-directional video via YouTube to a smartphone in a Google Cardboard VR-headset. We monitored such sessions, delivered via both WiFi and mobile networks, at different times of day, implying different levels of congestion, and characterised the network traffic by using the Coefficient of Throughput Variation (CoTV) as statistic. We observe that this statistic shows to be able to indicate whether a stream is stable or unstable, in terms of potential video playback freezes, when the DASH delivery strategy is used.

  • 128.
    Lagerspetz, E.
    et al.
    University of Helsinki, FIN.
    Flores, H.
    University of Helsinki, FIN.
    Mäkitalo, N.
    University of Helsinki, FIN.
    Hui, P.
    University of Helsinki, FIN.
    Nurmi, P.
    Lancaster University, GBR.
    Tarkoma, S.
    University of Helsinki, FIN.
    Passarella, A.
    IIT-CNR, ITA.
    Ott, J.
    Technical University of Munich, DEU.
    Reichl, P.
    University of Vienna, AUT.
    Conti, M.
    IIT-CNR, ITA.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Singh, J.
    University of Cambridge, GBR.
    Strufe, T.
    Technische Universität Dresden, DEU.
    Hossfeld, T.
    University of Duisburg-Essen, DEU.
    Lindgren, A.
    RISE SICS, SWE.
    Quercia, D.
    Bell Labs Cambridge, GBR.
    Pervasive Communities in the Internet of People2018Inngår i: 2018 IEEE International Conference on Pervasive Computing and Communications Workshops, PerCom Workshops 2018, Institute of Electrical and Electronics Engineers Inc. , 2018, s. 40-45, artikkel-id 8480273Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Internet has traditionally been a device-oriented architecture where devices with IP addresses are first-class citizens, able to serve and consume content or services, and their owners take part in the interaction only through those devices. The Internet of People (IoP) is a recent paradigm where devices become proxies of their users, and can act on their behalf. To realize IoP, new policies and rules for how devices can take actions are required. The role of context information grows as devices act autonomously based on the environment and existing social relationships between their owners. In addition, the social profiles of device owners determine e.g. how altruistic or resourceconserving they are in collaborative computing scenarios. In this paper we focus on community formation in IoP, a prerequisite for enabling collaborative scenarios, and discuss main challenges and propose potential solutions. © 2018 IEEE.

  • 129.
    Lorentzen, Charlott
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Johnson, Henric
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    On user perception of safety in online social networks2013Inngår i: International Journal of Communication Networks and Distributed Systems, ISSN 1754-3916, E-ISSN 1754-3924, Vol. 11, nr 1, s. 77-91Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Today, many people share personal information through online social networks. While these networks offer tremendous facilities to share one's life with family, friends and the outer world, users are also exposed to the risk to get their accounts compromized, with consequences for their professional and private lives. A strong password can help to ensure privacy, while in contrast, a weak password may lead to a compromized account. On the other hand, it is observed that users tend to shortcut laborious and time-consuming security measures, which alleges that their perception of their safety on the social network might deviate from the real safety situation. In this article, we investigate how users of social networks perceive safety, and to which extent they contribute to it. First, we examine the question in which way and to which extent a user's perception of safety is affected by increased response times. An investigation was conducted for teenage users of the online social network Facebook. Its results indicate that the users' perception of safety differs significantly in face of increased response times that usually imply worse Quality of Experience. Second, in order to find out to which extent users are aware of the risks associated with weak passwords as well as what measures have been taken to keep themselves secure and to ensure privacy, a survey about password complexity in online social networks was conducted with Swedish users. Our results of the survey indicate differences in password complexity between teenagers with different levels of technical education.

  • 130. Lorentzen, Charlott
    et al.
    Fiedler, Markus
    Johnson, Henric
    Jørstad, Ivar
    Decisive Factors for Quality of Experience of OpenID authentication using EAP-SIM2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    When using the web, large response times are bones of contention for users, i.e. they damp the Quality of Experience (QoE). Though, if one knew the cause of a large response time, one can examine what can be done about this obstacle. In this paper, we determine the weak point of the Extensible Authentication Protocol Method for GSM Subscriber Identity Modules (EAP-SIM) with the OpenID service with regards to excessive authentication times, which determine the response times. In order to provoke controlled raises of latter, we emulate bad network performance by introducing bi-directional delay between the supplicant (client) and the authenticator (server). Based on a recent, exponential relationship between QoE and response time, we then identify, quantify and compare the decisive factors for QoE reduction as functions of the components of the authentication times. The results we obtain clearly show that one task of the authentication contributes significantly more to the total response times than the other task, which points out the direction for future optimisation of user perception of authentication times.

  • 131. Lorentzen, Charlott
    et al.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Johnson, Henric
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Shaikh, Junaid
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Jørstad, Ivar
    On user perception of web login: a study on QoE in the context of security2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    From the user point of view, security has shown to be ambivalent; on one hand it is felt necessary, but on the other hand it is felt disturbing. Authentication solutions, for instance, are designed to keep undesired and unauthorized users out; however, allowed users need to spend some effort and waiting time when logging into a system. The question remains to which extent this effort is perceived as positive as security is increased, or negative through the waiting time spent in the process. Excessive waiting times imply the risk of user churn. As there is a lack of such studies, this paper investigates user perception (Quality of Experience, QoE) of the response times (Quality of Service, QoS) of a web authentication procedure, in particular a login to a community web page. Comparing the results to well-known user perception of web performance, we show that the users perceive logins in a similar way as standard web pages, which means that similar limits on user patience apply. The derived QoE-QoS relationship, an exponential function, serves then as the basis for assessing the performance of authentication algorithms in the domain of user acceptability.

  • 132. Lorentzen, Charlott
    et al.
    Fiedler, Markus
    Lorentzen, Peter
    Decisive Factors for Quality of Experience of OpenID Authentication Using EAP2011Inngår i: Advances in Electronics and Telecommunications, ISSN 2081-8580, Vol. 2, nr 3, s. 79-87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    When using the web, long response times are bones of contention for users, i.e. they damp the Quality of Experience (QoE). Though, if one knows the cause of the long response time one may examine what could be done to eliminate the obstacle. In this paper, we determine the weak point of the Extensible Authentication Protocol Method for GSM Subscriber Identity Modules (EAP-SIM) with the OpenID service with regards to excessive authentication times, which determine the response times. In order to provoke controlled increases of the latter, we emulate bad network performance by introducing bi-directional delay between the supplicant (client) and the authentication server. The same procedure is also applied to several other EAP methods. Based on a recent, exponential relationship between QoE and response time, we then identify, quantify and compare the decisive factors for QoE reduction as functions of the components of the authentication times. The results we obtain clearly show that one task of the EAP-SIM authentication contributes significantly more to the total response times than the other tasks, which points out the direction for future optimisation of user perception of authentication times.

  • 133. Marias, Giannis
    et al.
    Barros, Joao
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fischer, Andreas
    Hauff, Harald
    Herkenhoener, Ralph
    Grillo, Antonio
    Lentini, Alessandro
    Lima, Luisa
    Lorentzen, Charlott
    Security and privacy issues for the network of the future2012Inngår i: Security and Communication Networks, ISSN 1939-0114, E-ISSN 1939-0122, Vol. 5, nr 9, s. 987-1005Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The vision towards the Network of the Future cannot be separated from the fact that today's networks, and networking services are subject to sophisticated and very effective attacks. When these attacks first appeared, spoofing and distributed denial-of-service attacks were treated as apocalypse for networking. Now, they are considered moderate damage, whereas more sophisticated and inconspicuous attacks, such as botnets activities, might have greater and far reaching impact. As the Internet is expanding to mobile phones and smart dust and as its social coverage is liberalized towards the realization of ubiquitous computing (with communication), the concerns on security and privacy have become deeper and the problems more challenging than ever. Re-designing the Internet as the Network of the Future is self-motivating for researchers, and security and privacy cannot be provided again as separate, external, add-on, solutions. In this paper, we discuss the security and privacy challenges of the Network of the Future and try to delimit the solutions space on the basis of emerging techniques. We also review methods that help the quantification of security and privacy in an effort to provide a more systematic and quantitative treatment of the area in the future.

  • 134. Minhas, Tahir Nawaz
    et al.
    Fiedler, Markus
    Impact of Disturbance Locations on Video Quality of Experience2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Quality of experience is getting the attention of the research community as well as the industry. In case of real-time streaming, packet loss, delay and jitter degrades the video quality. The player buffer can be emptied due to long delay, which freezes video at playout, while resuming the streaming video content causes jumps to current location. There is the question, how user is going to react to such kind of artifacts with respect to location where they arise. We collected user ratings for videos showing the artifacts due to delay variation as well as freezes and jumps at different locations. We also verified these results with Perceptual Evaluation of Video Quality (PEVQ) application. For delay and delay variation case, the PEVQ results are aligning to the human rating, but both differ in freeze-and-jump case. The users' responses in case of freeze-and-jump shows interesting results with respect to location.

  • 135.
    Minhas, Tahir Nawaz
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Quality of Experience Hourglass Model2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recently, user perception has been receiving increasingly much attention of service providers, operators, manufactures and researchers. They are interested to know how the users perceive the quality of multimedia streaming services. To avoid the fatigue of subjective testing, they are interested to model the Quality of Experience (QoE) based on Quality of Service (QoS) and other measurable parameters. However, these parameters to estimate the QoE may differ per service. In this paper, we propose a conceptual model of QoE in parallel with the classical internet architecture hourglass model. Moreover conditions are highlighted under which QoE can be evaluated objectively from QoS without entailing other factors. The main is goal to understand the factors that are playing a significant role for QoE. We also discuss and explain the role of the application on QoE.

  • 136. Minhas, Tahir Nawaz
    et al.
    Fiedler, Markus
    Arlos, Patrik
    Quantification of Packet Delay Variation through the Coefficient of Throughput Variation2010Konferansepaper (Fagfellevurdert)
    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.

  • 137.
    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 shapers2011Konferansepaper (Fagfellevurdert)
    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.

  • 138.
    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 QoE2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With the growth of the mobile internet, the popularity of multimedia services and applications have increased rapidly. As a result, end-users become quality-conscious. To fulfill the users' expectations, the study of quality of experience (QoE) is becoming very important for both researchers and service providers. This paper analyses the impact on perceived quality of received videos encoded with the H.264 baseline profile, which is suitable for mobile video, and streamed through an emulated network with packet loss and packet delay variation. To evaluate the video QoE, tests are conducted on a mobile device and on a laptop. The users' responses show that the baseline profile of H.264 is very sensitive to packet loss and packet delay variation. Moreover, there is no considerable impact on users' perception either test is conducted on the mobile device or on the laptop by playing the same resolution video.

  • 139.
    Minhas, Tahir Nawaz
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Nawaz, Omer
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Khatibi, Siamak
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    The Effects of Additional Factors on Subjective Quality Assessments2019Inngår i: 2nd International Conference on Advancements in Computational Sciences, ICACS 2019, Institute of Electrical and Electronics Engineers Inc. , 2019, s. 120-124, artikkel-id 8689138Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In Quality of Experience, the users' degrees of delight or annoyance are quantized by direct human interaction via subjective quality assessments. There are many factors that may influence the users' responses, and standards have been laid down to strictly control the monitoring conditions. In this paper, we analyze limitations of Mean Opinion Score (MOS) assessment to portray the influence of additional factors on user behavior while assessing multimedia content. We show that the frequency of watching online video content as well as the user delight with the content play a significant role in her final feedback. Our study emphasizes the need to use additional metrics along with MOS for content ratings to obtain a more accurate measure of the user experience. © 2019 The University of Lahore.

  • 140.
    Minhas, Tahir Nawaz
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Shahid, Muhammad
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Lövström, Benny
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Rossholm, Andreas
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    QoE rating performance evaluation of ITU-T recommended video quality metrics in the context of video freezes2016Inngår i: Australian Journal of Electrical and Electronics Engineering, ISSN 1448-837X, Vol. 13, nr 2, s. 122-131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In real-time video streaming, video quality can be degraded due to network performance issues. Among other artefacts, video freezing and video jumping are factors that influence user experience. Service providers, operators and manufacturers are interested in evaluating the quality of experience (QoE) objectively because subjective assessment of QoE is expensive and, in many user cases, subjective assessment is not possible to perform. Different algorithms have been proposed and implemented in this regard. Some of them are in the recommendation list of the ITU Telecommunication Standardization Sector (ITU-T). In this paper, we study the effect of the freezing artefact on user experience and compare the mean opinion score of these videos with the results of two algorithms, the perceptual evaluation of video quality (PEVQ) and temporal quality metric (TQM). Both metrics are part of the ITU-T Recommendation J.247 Annex B and C. PEVQ is a full-reference video quality metric, whereas TQM is a no-reference quality metric. Another contribution of this paper is the study of the impact of different resolutions and frame rates on user experience and how accurately PEVQ and TQM measure varying frame rates.

  • 141.
    Minhas, Tahir
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Shahid, Mohammad
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Rossholm, Andreas
    Lövström, Benny
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Assessment of the Rating Performance of ITU-T Recommended Video Quality Metrics in the Context of Video Freezes2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Video streaming and multimedia applications are getting popular with the growth of networks. In real-time video streaming, video quality can be degraded due to network performance issues. Among other artifacts, freezing and frame dropping are factors that influence user experience. Service providers, operators, and researchers are interested to measure the Quality of Experience objectively. Different algorithms have been proposed and implemented in this regard. Some of them are in the recommendation list of the ITU Telecommunication Standardization Sector (ITU-T). In this paper, we study the effect of the freezing artifact on user experience and compare the mean opinion score (MOS) of these videos with the results of two algorithms, Perceptual Evaluation of Video Quality (PEVQ) and Temporal Quality Metric, both being part of ITU-T Recommendation J.247 Annex B and C, respectively. Another contribution of this paper is the investigation of the impact of different resolutions and frame rates on user experience.

  • 142.
    Muzahim Aziz, Hussein
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Grahn, Hakan
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Adapting the Streaming Video on the Estimated Motion Position2012Inngår i: Advances in Electrical and Electronic Engineering, ISSN 1336-1376, E-ISSN 1804-3119, Vol. 10, nr 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In real time video streaming, the frames must meet their timing constraints, typically specified as their deadlines. Wireless networks may suffer from bandwidth limitations. To reduce the data transmission over the wireless networks, we propose an adaption technique in the server side by extracting a part of the video frames that considered as a Region Of Interest (ROI), and drop the part outside the ROI from the frames that are between reference frames. The estimated position of the selection of the ROI is computed by using the Sum of Squared Differences (SSD) between consecutive frames. The reconstruction mechanism to the region outside the ROI is implemented in the mobile side by using linear interpolation between reference frames. We evaluate the proposed approach by using Mean Opinion Score (MOS) measurements. MOS are used to evaluate two scenarios with equivalent encoding size, where the users observe the first scenario with low bit rate for the original videos, while for the second scenario the users observe our proposed approach with high bit rate. The results show that our technique significantly reduces the amounts of data are streamed over wireless networks, while the reconstruction mechanism will provides acceptable video quality.

  • 143.
    Muzahim Aziz, Hussein
    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.
    Adapting the Streaming Video Based on the Estimated Position of the Region of Interest2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Streaming real time video over wireless networks cannot guarantee that all the frames could meet their deadlines. Wireless networks may suffer from bandwidth limitations. To reduce the streaming data over wireless networks, we propose a technique to identify, and extract the Region Of Interest (ROI), and drop the non-ROI from the frames that are between the reference frames. The Sum of Absolute Differences (SAD) will compute the consecutive video frames to identify the ROI as it considered the most motion and important region. The reconstruction mechanism to the non-ROI is performed on the mobile side by applying linear interpolation between the reference frames. We evaluate the proposed approach by using Mean Opinion Score (MOS) measurements. MOS are used to evaluate the two scenarios with equivalent encoding size, where the users observe the first scenario with a low bit rate for the original videos, while for the second scenario the users observe our proposed approach. The results show that our technique significantly reduces the amount of data, while the reconstruction mechanism provides acceptable video quality to the mobile viewers.

  • 144.
    Muzahim Aziz, Hussein
    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.
    Distribute the Video Frame Pixels over the Streaming Video Sequence as Sub-Frames2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Real-time video streaming over wireless channel has become an important issue due to the limited bandwidth that is unable to handle the flow of information of the video frames. The characteristics of wireless networks in terms of the available bandwidth, frame delay, and frame losses cannot be known in advance. As the effect of that, the user may notice a frozen picture in the mobile screen. In this work, we propose a technique to prevent freezing frames in the mobile devices based on spatial and temporal locality for the video stream, by splitting the video frame into four sub-frames and combining them with another sub-frames from different sequence positions in the streaming video. In case of frames losses, there is still a possibility that one fourth (one sub-frame) of the frame will be received by the mobile device. The received sub-frames will be reconstructed based on the surrounding pixels. The rate adaptation mechanism will be also highlighted in this work, by skipping sub-frames from the video frames. We show that the server can skip up to 75% of the frame’s pixels and the receiving pixels (sub-frames) can be reconstructed to acceptable quality in the mobile device.

  • 145.
    Nawaz, Omer
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Gehrmann, Christian
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Secure Mobile Social Networks using USIM in a Closed Environment2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Online social networking and corresponding mobile based applications are gaining popularity and now considered a well-integrated service within mobile devices. Basic security mechanisms normally based on passwords for the authentication of social-network users are widely deployed and poses a threat for the user security. In particular, for dedicated social groups with high confidentiality and privacy demands, stronger and user friendly principles for the authentication and identification of group members are needed. On the other hand, most of the mobile units already provide strong authentication procedures through the USIM/ISIM module. This paper explores how to build an architectural framework for secure enrolment and identification of group members in dedicated closed social groups using the USIM/SIM authentication and in particular, the 3GPP Generic Authentication Architecture (GAA), which is built upon the USIM/SIM capabilities. One part of the research is to identify the marketable use-cases with corresponding security challenges to fulfil the requirements that extend beyond the online connectivity. This paper proposes a secure identification design to satisfy the security dimensions for both online and offline peers. We have also implemented an initial proof of the concept prototype to simulate the secure identification procedure based on the proposed design. Our implementation has demonstrated the flexibility of the solution to be applied independently for applications requiring secure identification.

  • 146.
    Nawaz, Omer
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem. Blekinge Inst Technol, Dept Commun Syst, Karlskrona, Sweden..
    Minhas, Tahir Nawaz
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem. Blekinge Inst Technol, Dept Commun Syst, Karlskrona, Sweden..
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem. Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem. Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation. Blekinge Inst Technol, Dept Commun Syst, Karlskrona, Sweden..
    Optimal MTU for Realtime Video Broadcast with Packet Loss - A QoE Perspective2014Inngår i: 2014 9TH INTERNATIONAL CONFERENCE FOR INTERNET TECHNOLOGY AND SECURED TRANSACTIONS (ICITST), IEEE , 2014, s. 396-401Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Multimedia applications have become the prime source of Internet traffic in recent years due to high bandwidth offered by almost all access mechanisms. This highlights the need of intense research efforts to improve the already demanding user perception levels for high-performance video delivery networks. Quality of Experience (QoE) based metrics are often used to quantify user satisfaction levels regarding an application or service. In this paper, we have analyzed the impact of variable frame sizes at link layer with different packet loss scenarios to evaluate the performance degradation of H.264 based live video streams from the end user perspective using subjective tests. We have focused on both subjective and objective quantitative measures to analyze the myth that smaller packets provide better quality in error-prone networks. We found that this assumption may not be true for some cases with a considerable packet loss ratio. Moreover, we observed that full-reference video assessment software like PEVQ predicts QoE to an acceptable extent, which allows cutting cost and effort coming with subjective evaluations. Keywords-Quality of Experience, Multimedia communication, Streaming media

  • 147.
    Nawaz, Omer
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Minhas, Tahir Nawaz
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för teknik och estetik.
    QoE based comparison of H.264/AVC and WebM/VP8 in an error-prone wireless network2017Inngår i: Proceedings of the IM 2017 - 2017 IFIP/IEEE International Symposium on Integrated Network and Service Management / [ed] Chemouil P.,Simoes P.,Madeira E.,Secci S.,Monteiro E.,Gaspary L.P.,dos Santos C.R.P.,Charalambides M., Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1005-1010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Quality of Experience (QoE) management is a prime topic of research community nowadays as video streaming, online gaming and security applications are completely reliant on the network service quality. Moreover, there are no standard models to map Quality of Service (QoS) into QoE. HTTP media streaming is primarily used for such applications due to its coherence with the Internet and simplified management. The most common video codecs used for video streaming are H.264/AVC and Google's VP8. In this paper, we have analyzed the performance of these two codecs from the perspective of QoE. The most common end-user medium for accessing video content is via home based wireless networks. We have emulated an error-prone wireless network with different scenarios involving packet loss, packet delay and delay variation. The focus of this paper is evaluating the end user satisfaction with the multimedia content by subjective assessment using Mean Opinion Score (MOS). We have observed the overall superiority of H.264/AVC but the VP8 codec strongly gains ground in highly error-prone networks in terms of user satisfaction. © 2017 IFIP.

  • 148. Persson, Jan A.
    et al.
    Davidsson, Paul
    Boldt, Martin
    Carlsson, Bengt
    Fiedler, Markus
    Evaluation of Road User Charging Systems: The Swedish Case2007Konferansepaper (Fagfellevurdert)
  • 149. Polyzos, George
    et al.
    Giannis, Marias
    Arkoulis, Stamatios
    Frangoudis, Pantelis
    Fiedler, Markus
    Popescu, Adrian
    Meer, Hermann de
    Herkenhöner, Ralph
    Fischer, Andreas
    Oberender, Jens
    ASPECTS: Agile spectrum security2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cognitive Radio (CR) promises to provide better spectrum utilization and increase the availability of (on demand) broadband access to the Network of the Future. CR relies on devices that can sense their (radio) environment, understand it, and model it, so that they can exploit the spectrum through appropriate transmission parameters (in the space, time, and frequency domains) that do not interfere with legacy and/or licensed devices using the same spectrum in the same general area. According to the CR paradigm, the use of the spectrum that is not used by primary (licensed) users is opportunistic. Secondary users sense the spectrum and decide to use it on their own, possibly following additional rules and protocols. Because multiple such CR devices (secondary users) can find themselves in the same area and compete for the same spectrum, the question that arises is whether these devices behave fairly and appropriately. The opportunities are there for competing CR devices to try to grab more resources through the spreading of misinformation and impersonation of licensed devices.

  • 150.
    Popescu, Adrian
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Erman, David
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ilie, Dragos
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Popescu, Alexandru
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Vogeleer, Karel De
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Seamless Roaming: Developments and Challenges2011Inngår i: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 5233, s. 795-807Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chapter reports on recent developments and challenges focused on seamless handover. These are subject for the research projects MOBICOME and PERIMETER, recently granted by the EU EUREKA and EU STREP FP7, respectively. The research projects are considering the recently advanced IP Multimedia Subsystem (IMS), which is a Set of technology standards put forth by the Internet Engineering Task Force (IETF) and two Third Generation Partnership Project groups, namely 3GPP and 3GPP2. The foundation of seamless handover is provided by several components, the most important ones being the handover, mobility management, connectivity management and Internet mobility. The paper provides an intensive analysis of these components.

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