Martín Varela - VTT



I am a Principal Scientist at VTT Technical Research Centre of Finland. I work in the Network Performance team, within the Communication Systems expert area. My main area of expertise is Quality of Experience (QoE) for multimedia services, although I also dabble in other topics related to QoS and networking.


I am currently leading VTT's research in the QoE domain. At the moment our work is focused mostly on media services, but we have been working towards expanding our QoE expertise into other domains, in particular those related to Cloud Services.

Our team is currently involved in several European QoS/QoE related projects, such as CELTIC IPNQSIS , (the now finished) CELTIC Easy Wireless 2, and the CELTIC QuEEN project, for which I'm the Technical Coordinator. I am also a management committee member in COST Action IC1003 - QUALINET.

A copy of my CV can be found here

Research

My research interests are centered around Quality of Experience (mainly for networked multimedia and other applications), and its applications to network control and optimization, pricing, and Service Level Agreements definition. I work on reference-free, parametric models for real-time QoE estimation, since those usually are the most suitable for control applications.

One of the subjects that I am currently interested in is the development QoE-aware control mechanisms that can improve the quality perceived by the user by acting both at the application and network levels. Suitable parametric models for quality allow to assess the impact of different network impairments and application configuration parameters on the QoE, and this knowledge can be in turn used to take corrective actions when needed. For example, vertical handovers can be triggered in multi-access devices, or application-level configurations can be changed to better suit the current network conditions (e.g. increase redundancy if packet losses are high, or modify the number of enhcancement layers in use in an SVC stream).

I am also working on ways to define, understand and improve QoE for non-media services, in particular for Web-based services (WebQoE). This is particularly interesting for Cloud services, and work on this subject was spear-headed within the TIVIT Cloud Software Program. There are many possible applications for QoE estimators for generic services, ranging from SLA definition and enforcement, Operating Support Systems, datacenter management, and of course QoE optimization for the different services. A large effort in this area is underway within the CELTIC QuEEN project.

Publications

Essays and Other Publications

  • Martín Varela "Quality of Service and Experience - Lost in the Cloud". In T. Huomo, K. Karppinen and P. Pussinen (eds.) Value-driven Business in the Cloud - VTT Research Highlights 9, 2013
  • Martín Varela and Janne Seppänen "Video Quality as a Driver for Traffic Management with Multiple Subscriber Classes" IEEE Communications Society MMTC E-Letter, Vol.8, No.2, March 2013.
  • Patrick Le Callet, Sebastian Möller and Andrew Perkis (eds) "Qualinet White Paper on Definitions of Quality of Experience". European Network on Quality of Experience in Multimedia Systems and Services (COST Action IC 1003), June 2012.
  • Martín Varela. "Some Musings on QoE Definitions - Philosophy and Practice". January 2012.
  • Martín Varela. "Gilbert-model Loss Trace Generator for Instrumentation of Subjective Assessment Campaigns". January 2012. (source code on GitHub)
  • Martín Varela and Jouko Sankala. "Understanding Quality Issues in the Cloud". White paper for the TIVIT Cloud Software Program. November 2010.

Book Chapters

  • Martín Varela, Lea Skorin-Kapov, Katrien De Moor and Peter Reichl. "QoE - Defining a User-centric Concept for Service Quality". To be published in C. Chen, P. Chatzimisios and T. Dagiuklas (eds.) "Multimedia Quality of Experience (QoE): Current Status and Future Requirements", John Wiley & Sons (in production).
  • Frédéric Guyard, Martín Varela, Lea Skorin-Kapov, Antonio Cuadra and Pedro Sevilla. "Quality of Experience Estimators in Networks". To be published in A. Mellouk and A. Cuadra (eds.) "Quality of Experience Engineering for Customer Added Value Services: From Evaluation to Monitoring", Iste / Wiley & Sons, 2014 (in press).
  • Antonio Cuadra, Mar Cutanda, Andreas Aurelius, Kjell Brunströmm, Jorge López de Vergara, Martín Varela, Jukka-Pekka Laulajainen, Anderson Morais, Ana Cavalli, Abdelhamid Mellouk, Brice Augustin and Ismael Pérez Mateos. "Ecosystem for Customer Experience Management". To be published in A. Mellouk and A. Cuadra (eds.) "Quality of Experience Engineering for Customer Added Value Services: From Evaluation to Monitoring", Iste / Wiley & Sons, 2014 (in press).
  • Martín Varela, Lea Skorin-Kapov and Touradj Ebrahimi. "Quality of Service vs. Quality of Experience". In S. Möller, A. Raake (eds.) "Quality of Experience: Advanced Concepts, Applications and Methods", Springer, 2014, ISBN 978-3-319-02680-0.

Journal Articles

  • Martín Varela, Lea Skorin-Kapov, Frédéric Guyard and Markus Fiedler. "Meta-Modeling QoE - Towards a Generic Methodology for Building QoE Models". Accepted for publication in PIK - Praxis der Informationverarbeitung und -kommunikation
  • Janne Seppänen, Martín Varela and Aggeliki Sgora. "An Autonomous QoE-Driven Network Management Framework". Journal of Visual Communication and Image Representation 25(3):565-577, April 2014 - DOI
  • Tobias Hoßfeld, Raimund Schatz, Martín Varela and Christian Timmerer. "Challenges of QoE Management for Cloud Applications". IEEE Communications Magazine, 50(4):28-36, April 2012.
  • Jochen Eisl, Matthias Lott, Gerhard Kuhn, Martín Varela, Jarmo Prokkola, Toni Mäki, Jukka-Pekka Laulajainen. "Analysis of Managed and Over-the-Top Streaming Services in Mobile Networks". PIK - Praxis der Informationverarbeitung und -kommunikation 35:1-7, 2012.
  • Ana Paula Couto da Silva, Martín Varela, Edmundo de Souza e Silva, Rosa Leão, and Gerardo Rubino. "Quality Assessment of Interactive Real Time Voice Applications". Computer Networks 52(6):1179-1192. April 2008.
  • Gerardo Rubino, Martín Varela and Jean-Marie Bonnin. "Controlling Multimedia QoS in the Future Home Network Using the PSQA Metric". The Computer Journal 49(2):137-155, 2006.
  • Samir Mohamed, Gerardo Rubino, and Martín Varela. "Performance Evaluation of Real-time Speech Through a Packet Network: a Random Neural Networks-based Approach". Performance Evaluation, 57(2):141-162, 2004.

Conference Articles

  • Martín Varela, Toni Mäki, Juho Merilahti, Eva Rodríguez and Arnaud Runge "QuoTe - An Extensible Platform for QoE Monitoring and Benchmarking of Telemedicine Applications". Accepted for publication in SSH 2014: IEEE International Workshop on Service Science for eHealth, Natal, Brazil, October 2014.
  • Pantelis Frangoudis, Aggeliki Sgora, Martín Varela and Gerardo Rubino "Quality-Driven Optimal SLA Selection for Enterprise Cloud Communications". In Proceedings of IEEE ICC / QoENAM 2014, Sydney, Australia, June 2014.
  • Katrien De Moor, Filippo Mazza, Isabelle Hupont, Miquel Ríos Quintero, Toni Mäki and Martín Varela "Chamber QoE - A Multi-instrumental Apporach to Explore Affective Aspects in relation to Quality of Experience". In proceedings of SPIE/HVEI 2014, San Francisco, U.S.A, January 2014.
  • Martín Varela, Toni Mäki, Lea Skorin-Kapov and Tobias Hoßfeld. "Increasing Payments in Crowdsourcing: Don't Look a Gift Horse in the Mouth!". In proceedings of PQS 2013, Vienna, Austria, September 2013.
  • Martín Varela, Toni Mäki, Lea Skorin-Kapov and Tobias Hoßfeld. "Towards an Understanding of Visual Appeal in Website Design". In proceedings of QoMEX 2013, Klagenfurt, Austria, July 2013.
  • Toni Mäki, Dragan Kukolj, Dragana Ðordević and Martín Varela. "A Reduced-Reference Parametric Model for Audiovisual Quality of IPTV Services". In proceedings of QoMEX 2013, Klagenfurt, Austria, July 2013.
  • Toni Mäki, Martín Varela and Jukka-Pekka Laulajainen. "Estimating the Effect of Context on QoE of Audiovisual Services: Laboratory vs. Public Places". In proceedings of IWQM/SaCoNet 2013, Paris, France, June 2013.
  • Antonio Cuadra, Mar Cutanda, Andreas Aurelius, Kjell Brunströmm, Jorge Lopez de Vergara, Martín Varela, Jukka-Pekka Laulajainent, Anderson Morais, Ana Cavalli, Ismael Perez-Mateos "Ecosystem for Customer Experience Assurance". (position paper). Accepted for publication in IWQM/SaCoNet 2013, Paris, France, June 2013.
  • Janne Seppänen and Martín Varela. "QoE-Driven Network Management for Real-Time Over-the-Top Multimedia Services". In proceedings of IEEE WCNC 2013, April 2013, Shanghai, China.
  • Lea Skorin-Kapov and Martín Varela. "A Multi-Dimensional View of QoE: the ARCU Model". In proceedings of MIPRO 2012, May 2012, Opatija, Croatia.
  • Antonio Cuadra-Sánchez, Mar Cutanda-Rodríguez, Ismael Pérez-Mateos, Andreas Aurelius, Kjell Brunströmm, Jukka-Pekka Laulajainen, Martín Varela and Jorge López de Vergara. "A Global Customer Experience Management Architecture". Future Network and Mobile Summit, July 2012, Berlin, Germany.
  • Martín Varela and Jukka-Pekka Laulajainen. "QoE-Driven Mobility Management - Integrating the Users' Quality Perception into Network-level Decision Making". In proceedings of QoMEX, September 2011, Mechelen, Belgium.
  • Martín Varela and Jukka-Pekka Laulajainen. "Terminal-side QoE Estimations for Cross-Layer Network Control". In proceedings of WWIC'11, June 2011, Vilanova i la Geltrú, Spain.
  • Sebastián Basterrech, Gerardo Rubino and Martín Varela. "Single-Sided Real-Time PESQ Score Estimation". In proceedings of MESAQIN'09, June 2009, Prague, Czech Republic.
  • Pekka Perälä and Martín Varela. "Some Experiences with VoIP Over Converging Networks". In proceedings of MESAQIN'07, June 2007, Prague, Czech Republic.
  • Yezekael Hayel, Gerardo Rubino, Bruno Tuffin and Martín Varela. "A New Way of Thinking Utility in Pricing Mechanisms: A Neural Network Approach". In Proceedings of CLAIO 2006, November 2006, Montevideo, Uruguay.
  • Gerardo Rubino, Pierre Tirilly and Martín Varela. "Evaluating Users' Satisfaction in Packet Networks Using Random Neural Networks". In proceedings of ICANN'06, September 2006, Athens, Greece .
  • Martín Varela, Ian Marsh, Björn Grönvall and Florian Hammer. "A Metric for Single-ended Speech Quality Estimation" In proceedings of 4th Swedish National Computer Networking Workshop SNCNW 2006, October 2006, Luleå, Sweden.
  • Martín Varela, Ian Marsh and Björn Grönvall. "A Systematic Study of PESQ's Performance (from a Networking Perspective)" In Proceedings of the Measurement of Speech and Audio Quality in Networks Workshop (MESAQIN'06), Prague, Czech Republic, June 2006.
  • Gerardo Rubino, Martín Varela and Jean-Marie Bonnin. "Wireless VoIP at Home: Are We There Yet?" In Proceedings of the Measurement of Speech and Audio Quality in Networks Workshop (MESAQIN'05), Prague, Czech Republic, June 2005.
  • Martín Varela. "Studying the Effects of FEC on Voice Traffic Using PSQA (extended abstract)". In INFOCOM'05 Student Workshop, Miami, USA, March 2005. (poster )
  • Martín Varela. "Évaluation Pseudo-subjective de la Qualité des Flux VoIP: un Approche par Réseaux de Neurones Aléatoires". In Proceedings of JDIR'04, Lannion, France, November 2004 (in French)
  • Gerardo Rubino and Martín Varela. "Evaluating the Utility of Media-dependent FEC in VoIP Flows". In LNCS 3266: Proceedings of the Fifth International Workshop on Quality of future Internet Services (QofIS'04), Barcelona, Spain, September 2004.
  • Gerardo Rubino and Martín Varela. "A New Approach for the Prediction of End-to-End Performance of Multimedia Streams". In Proceedings of the First International Conference on Quantitative Evaluation of Systems (QEST'04), Enschede, The Netherlands, September 2004.
  • Catherine Colomes, Martín Varela, and Jean-Charles Gicquel. "Subjective Audio Tests: Quality of Some Codecs When Used in IP Networks". In Proceedings of the Measurement of Speech and Audio Quality in Networks Workshop (MESAQIN'04), Prague, Czech Republic, June 2004.
  • Samir Mohamed, Gerardo Rubino, and Martín Varela. "A Method for Quantitative Evaluation of Audio Quality Over Packet Networks and its Comparison with Existing Techniques". In Proceedings of the Measurement of Speech and Audio Quality in Networks Workshop (MESAQIN'04), Prague, Czech Republic, June 2004.
  • Daniel Perovich, Leonardo Rodríguez and Martín Varela. "Historias Clínicas en Tarjetas Inteligentes". In Proceedings of the 30th Jornadas Argentinas De Informática e Investigación Operativa (JAIIO), Buenos Aires, Argentina, September 2001 (in Spanish).
  • Daniel Perovich, Leonardo Rodríguez and Martín Varela. "A Simple Methodology for Secure Object Sharing". In Proceedings of the 3rd Gemplus Developers Conference, Paris, France, June 2001.

Thesis

  • Martín Varela. "Pseudo-subjective Quality Assessment of Multimedia Streams and its Applications in Control", Ph.D. Dissertation, Université de Rennes 1, November 2005.
  • Martín Varela. "Mesure de la Qualité d'un Flux Multimédia Transporté sur Internet", Master's Thesis, Université de Rennes 1, July 2002.

Work related links

Other links

Contact Information

  Martín Varela
     VTT
     PL1100, FI-90571
     Oulu, Finland
  first.last@vtt.fi
  +358 20 722 2495