Martín Varela - VTT

My research interests are centered around Quality of Experience (for networked multimedia and other applications), and its applications to network control and optimization, pricing, and Service Level Agreements definition. I am working on reference-free, parametric models for real-time QoE assessment, 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, measure and improve QoE for non-media services. This is particlarly 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 metrics 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.

• Martín Varela, Toni Mäki, Lea Skorin-Kapov and Tobias Hoßfeld. "Increasing Payments in Crowdsourcing: Don't Look a Gift Horse in the Mouth!". Accepted for publication in 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". Accepted for publication in 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". Accepted for publication in 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". Accepted for publication in 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" (invited paper). 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.

• 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.