Seamless Secured Roaming over Heterogeneous Wireless Networks

First of all, I would like to express my deepest sense of gratitude to my supervisor, Prof. Nazim AGOULMINE, for his guidance, encouragement and excellent advice throughout my research work. I am thankful to the members of my thesis committee, Mikael SALAUN, Josef NOLL, Hossam AFIFI, Sasitharan BALASUBRAMANIAM, Romain DURAND for the time and effort that they invested in judging the contents of my thesis. I am pleased to thank all my colleagues at Networks and Multimedia Systems Research Group (LRSM) for their support and their comradeship; especially to Mehdi Nafa, Elyes Lehtihet, Yacine Ghamri Doudane and Quoc Thinh Nguyen, who worked closely with me in Polymage, SEIMONET and SUMO projects. Finally, I take this opportunity to express my profound gratitude to my beloved parents and sister for their invaluable love and support throughout the years. I cannot thank you enough for your unwavering support, encouragement, and for always believing in me. Lastly, I would like to thank my fiancé, for her love, encouragement and patience. ii