1. LTCI, INFRES, Telecom Paris, Institut Polytechnique de Paris, France
2. School of Computing Science, University of Glasgow, United Kingdom
3. CNRS i3, SES, Telecom Paris, Institut Polytechnique de Paris, France
4. TU-Darmstadt, Germany and LTCI, INFRES, Telecom Paris, Institut Polytechnique de Paris, France