First, I would like to thank here my advisor Dr Jörg Liebeherr, who gave me the opportunity to work on an this research problem, did not fail in trusting in my commitment, and patiently accepted to review hundreds of pages of the different versions of this thesis. Of course, this work would not have been possible without the support of his full research group, the Multimedia Networks Group (MNG). Working as a member of the MNGroup has truly been enjoyable.
I also do not forget that my presence here has been made possible by my former institution, the French Engineer School ``Ecole Centrale de Lille'', which does not let many students leave to the USA to pursue graduate studies.
Last but not least, thanks to my parents who have always been dedicated to my academic success.