We would like to express our gratitude to those who, in one way or another, helped us to get through with this project. First of all, our sincere thanks go to those who motivated us to start and continue this work. In particular to Jacob Benesty (Institut National de la Recherche Scientifique, Canada) who provided inspiration to start this work and continuously encouraged us along the way. We also thank Lajos Hanzo (University of Southampton, UK) whose friendly advice pushed us into this adventure.

We would also like to thank our collaborators who participated in various aspects of this work, most often as coauthors of publications. In particular, we thank Rodolfo Feick (Universidad Técnica Federico Santa María, Chile), Erik Agrell, Fredrik Brännström, Arne Svensson, Alexandre Graell i Amat, Christian Häger and Mikhail Ivanov (all from Chalmers University of Technology, Sweden), Albert Guillèn i Fábregas and Alfonso Martinez (both from Universitat Pompeu Fabra, Spain), and Tobias Koch (Universidad Carlos III de Madrid, Spain). Many thanks to the alumni of Universidad Técnica Federico Santa María: Francisco Pellegrini, Christian Gonzalez, Marcos Bacic, Rolando Bettancourt, Andrés Cerón, Víctor Nuñez, as well as the alumni of Institut National de la Recherche Scientifique: Mustapha Benjillali and Thomas Chowdhury.

We are particularly grateful to Mikhail Ivanov, Christian Häger, Fredrik Brännström, Maël Le Treust (Centre National de la Recherche Scientifique, France), Martin Senst, and Jossy Sayir (University of Cambridge, UK) for providing feedback on preliminary versions of the manuscript. Thanks to Mr Aata El Hamss (Institut National de la Recherche Scientifique) for help with graphical presentation of some of the results.

We would also like to thank Wiley's staff: Mr Mark Hammond, Ms Suzan Barclay, and Ms Liz Wingett who were extremely patient with us during the project.

We acknowledge the support we received from the institutions we have had the chance to work at, including Institut National de la Recherche Scientifique (Canada), Chalmers University of Technology (Sweden), Laboratoire de Signaux et Systèmes of Centre National de la Recherche Scientifique (France), the University of Cambridge and University College London (UK).

Last but not least, our thanks go to different funding institutions which, over the years, financially supported our work. This includes the British Academy and The Royal Society, UK (under the Newton International Fellowship scheme), the European Community's Seventh's Framework Programme (under FP7/2007-2013 grants #271986 and #236068), the Swedish Research Council (under research grant #2006-5599), the Department of Signals and Systems, Chalmers University of Technology (under the Solveig and Karl G. Eliasson Memorial Fund), the European Commission (under projects NEWCOM++ #216715), the Comisión Nacional de Ciencia y Tecnología, Chile (under research grant PBCT-ACT-11/2004), the Natural Sciences and Engineering Research Council of Canada, and the Fonds québécois de la recherche sur la nature et les technologies, Quebec, Canada.