Quality of Experience Column: An Introduction

“Quality of Experience (QoE) is the degree of delight or annoyance of the user of an application or service. It results from the fulfillment of his or her expectations with respect to the utility and / or enjoyment of the application or service in the light of the user’s personality and current state.“ (Definition from the Qualinet Whitepaper 2013).

Research on Quality of Experience (QoE) has advanced significantly in recent years and attracts attention from various stakeholders. Different facets have been addressed by the research community like subjective user studies to identify QoE influence factors for particular applications like video streaming, QoE models to capture the effects of those influence factors on concrete applications, QoE monitoring approaches at the end user site but also within the network to assess QoE during service consumption and to provide means for QoE management for improved QoE. However, in order to progress in the area of QoE, new research directions have to be taken. The application of QoE in practice needs to consider the entire QoE eco-system and the stakeholders along the service delivery chain to the end user.

The term Quality of Experience dates back to a presentation in 2001 (interestingly, at a Quality of Service workshop) and Figure 1 depicts an overview of QoE showing some of the influence factors.


Figure 1. Quality of Experience (from Ebrahimi’09)

Different communities have been very active in the context of QoE. A long-established community is Qualinet which started in 2010. The Qualinet community (www.qualinet.eu) provided a definition of QoE in its [Qualinet Whitepaper] which is a contribution of the European Network on Quality of Experience in Multimedia Systems and Services, Qualinet (COST Action IC 1003), to the scientific discussion about the term QoE and its underlying concepts. The concepts and ideas cited in this paper mainly refer to the Quality of Experience of multimedia communication systems, but may be helpful also for other areas where QoE is an issue. Qualinet is organized in different task forces which address various research topics: Managing Web and Cloud QoE; Gaming; QoE in Medical Imaging and Healthcare; Crowdsourcing; Immersive Media Experiences (IMEx). There is also a liaison relation with VQEG and a task force on Qualinet Databases providing a platform with QoE-related dataset. The Qualinet database (http://dbq.multimediatech.cz/) is seen as a key for current and future developments in Quality of Experience, which resides in a rich and internationally recognized database of content of different sorts, and to share such a database with the scientific community at large.

Another example of the Qualinet activities is the Crowdsourcing task force. The goal of this task force is among others to identify the scientific challenges and problems for QoE assessment via crowdsourcing but also the strengths and benefits, and to derive a methodology and setup for crowdsourcing in QoE assessment including statistical approaches for proper analysis. Crowdsourcing is a popular approach that outsources tasks via the Internet to a large number of users. Commercial crowdsourcing platforms provide a global pool of users employed for performing short and simple online tasks. For quality assessment of multimedia services and applications, crowdsourcing enables new possibilities by moving the subjective test into the crowd resulting in larger diversity of the test subjects, faster turnover of test campaigns, and reduced costs due to low reimbursement costs of the participants. Further, crowdsourcing allows easily addressing additional features like real-life environments. Crowdsourced quality assessment however is not a straightforward implementation of existing subjective testing methodologies in an Internet-based environment. Additional challenges and differences to lab studies occur, in conceptual, technical, and motivational areas. The white paper [Crowdsourcing Best Practices] summarizes the recommendations and best practices for crowdsourced quality assessment of multimedia applications from the Qualinet Task Force on “Crowdsourcing” and is also discussed within the standardization ITU-T P.CROWD.

A selection of QoE related communities is provided in the following to give an overview on the pervasion of QoE in research.

  • Qualinet (http://www.qualinet.eu): European Network on Quality of Experience in Multimedia Systems and Services as outlined above. Qualinet is also technical sponsor of QoMEX.  
  • QoMEX (http://qomex.org/). The International Conference on Quality of Multimedia Experience (QoMEX) is a top-ranked international conference and among the twenty-best conferences in Google Scholar for subcategory Multimedia. In 2019, the 11th International Conference on Quality of Multimedia Experience  will be held in June 5th to 7th, 2019 in Berlin, Germany. It will bring together leading experts from academia and industry to present and discuss current and future research on multimedia quality, quality of experience (QoE) and user experience (UX). This way, it will contribute towards an integrated view on QoE and UX, and foster the exchange between the so-far distinct communities.
  • ACM SIGMM (http://www.sigmm.org/): Within the ACM community, QoE plays also a significant role in the major events like ACM Multimedia (ACM MM), where “Experience” is one of the four major themes. ACM Multimedia Systems (MMSys) regularly publishes works on QoE, and included special sessions on those topics in the last years. ACM MMsys 2019 will held from June 18 – 21, 2019 in Amherst, Massachusetts, USA.
  • ICME: The IEEE International Conference on Multimedia and Expo (IEEE ICME 2019) will be held from July 8-12, 2019 in Shanghai, China. It includes in the call for papers topics such as Multimedia quality assessment and metrics, and Multi-modal media computing and human-machine interaction.
  • ACM SIGCOMM (http://www.sigcomm.com): Within ACM SIGCOMM, Internet-QoE workshops have been initiated in 2016 and 2017. The focus of the last edition was on QoE Measurements, QoE-based Traffic Monitoring and Analysis, QoE-based Network Management.
  • Tracking QoE in the Internet Workshop: A summary and the outcomes of the “Workshop on Tracking Quality of Experience in the Internet” at Princeton gives a very good impression on the QoE activities in US with a recent focus on QoE monitoring and measurable QoE parameters in the presence of constraints like encryption.  
  • SPEC RG QoE (https://research.spec.org): The mission of SPEC’s Research Group (RG) is to promote innovative research in the area of quantitative system evaluation and analysis by serving as a platform for collaborative research efforts fostering the interaction between industry and academia in the field. The SPEC research group on QoE is the starting point for the release of QoE ideas, QoE approaches, QoE measurement tools, and QoE assessment paradigms.
  • QoENet (http://www.qoenet-itn.eu) is a Marie Curie project, whose focus is the analysis, design, optimization and management of the QoE in advanced multimedia services, creating a fully-integrated and multi-disciplinary network of 12 Early Stage Researchers working in and seconded by 7 academic institutions, 3 private companies and 1 standardization institute distributed in 6 European countries and in South Korea. The project is then fulfilling the major objective of training through research of the young fellows to broader the knowledge in the field of the new generation of researchers. Significant research results have been achieved in the field of: QoE for online gaming, social TV and storytelling, and adaptive video streaming; QoE management in collaborative ISP/OTT scenarios; models for HDR, VR/AR and 3D images and videos.
  • Many QoE-related activities at a national level are also happening. For example, a community of professors and researchers from Spain organize a yearly workshop entitled “QoS and QoE in Multimedia Communications” since 2015 (URL of its latest edition: https://bit.ly/2LSlb2N). This community is targeted at establishing collaborations, sharing resources, and discussing about the latest contributions and open issues. The community is also pursuing the creation of a national network on QoE (like the Spanish Qualinet), and then involving international researchers in that network.
  • There are several standardization-related activities ongoing e.g. in standardization groups ITU, JPEG, MPEG, VQEG. Their specific interest in QoE will be summarized in one of the upcoming QoE columns.

The first QoE column will discuss how to approach an integrated view of QoE and User Experience. While research on QoE has mostly been carried out in the area of multimedia communications, user experience (UX) has addressed hedonic and pragmatic usage aspects of interactive applications. In the case of QoE, the meaningfulness of the application to the user and the forces driving the use have been largely neglected, while in the UX field, respective research has been carried out but hardly been incorporated in a model combined with the pragmatic and hedonic aspects. In the first column will be dedicated to recent ideas “Toward an integrated view of QoE and User Experience”. To give the readers an impression on the expected contents, we foresee in the upcoming QoE columns topics to discuss about recent activities like

  • Point cloud subjective evaluation methodology
  • Complex, interactive narrative design for complexity
  • Large-Scale Visual Quality Assessment Databases
  • Status and upcoming QoE activities in standardization
  • Active Learning and Machine Learning for subjective testing and QoE modeling
  • QoE in 5G: QoE management in softwarized networks with big data analytics
  • Immersive Media Experiences e.g. for VR/AR/360° video applications

Our aim for SIGMM Records is to share insights from the QoE community and to highlight recent development, new research directions, but also lessons learned and best practices. If you are interested in writing for the QoE column, or have something you would like to know more about in this area, please do not hesitate to contact the editors. The SIGMM Records editors responsible for QoE are active in different communities and QoE research directions.

The QoE column is edited by Tobias Hoßfeld and Christian Timmerer.

[Qualinet Whitepaper] Qualinet White Paper on Definitions of Quality of Experience (2012).  European Network on Quality of Experience in Multimedia Systems and Services (COST Action IC 1003), Patrick Le Callet, Sebastian Möller and Andrew Perkis, eds., Lausanne, Switzerland, Version 1.2, March 2013.” Qualinet_QoE_whitepaper_v1.2

[Crowdsourcing Best Practices] Tobias Hoßfeld et al. “Best Practices and Recommendations for Crowdsourced QoE-Lessons learned from the Qualinet Task Force ‘Crowdsourcing’” (2014). Qualinet_CSLessonsLearned_29Oct2014

Hossfeld_Tobias Tobias Hoßfeld is full professor at the University of Würzburg, Chair of Communication Networks, and is active in QoE research and teaching for more than 10 years. He finished his PhD in 2009 and his professorial thesis (habilitation) “Modeling and Analysis of Internet Applications and Services” in 2013 at the University of Würzburg. From 2014 to 2018, he was head of the Chair “Modeling of Adaptive Systems” at the University of Duisburg-Essen, Germany. He has published more than 100 research papers in major conferences and journals and received the Fred W. Ellersick Prize 2013 (IEEE Communications Society) for one of his articles on QoE. Among others, he is member of the advisory board of the ITC (International Teletraffic Congress), the editorial board of IEEE Communications Surveys & Tutorials and of Springer Quality and User Experience.
ct2013oct Christian Timmerer received his M.Sc. (Dipl.-Ing.) in January 2003 and his Ph.D. (Dr.techn.) in June 2006 (for research on the adaptation of scalable multimedia content in streaming and constrained environments) both from the Alpen-Adria-Universität (AAU) Klagenfurt. He joined the AAU in 1999 (as a system administrator) and is currently an Associate Professor at the Institute of Information Technology (ITEC) within the Multimedia Communication Group. His research interests include immersive multimedia communications, streaming, adaptation, Quality of Experience, and Sensory Experience. He was the general chair of WIAMIS 2008, QoMEX 2013, and MMSys 2016 and has participated in several EC-funded projects, notably DANAE, ENTHRONE, P2P-Next, ALICANTE, SocialSensor, COST IC1003 QUALINET, and ICoSOLE. He also participated in ISO/MPEG work for several years, notably in the area of MPEG-21, MPEG-M, MPEG-V, and MPEG-DASH where he also served as standard editor. In 2012 he cofounded Bitmovin (http://www.bitmovin.com/) to provide professional services around MPEG-DASH where he holds the position of the Chief Innovation Officer (CIO).