To my Family and Friends. Acknowledgements

The thesis was possible thanks to the contribution of many people. Foremost among these is Prof. Fernando J. Velez, my thesis mentor, whose technical excellence and unconditional support where the keystone to achieve the goals of this project. The discussions during our weekly meetings revealed to be essential in the conception of our formulations, and his vision on what future heterogeneous networks will be, was essential for this work to take form. I am grateful to Prof. Neeli Prasad for her mentoring and for welcoming me for several months in her group at the CTIF of Aalborg University. It allowed me to work in an international group for mobile communications research, with different expertise and experience. It allowed me to acquire valuable work experience. The group and individual objectives changed my view over research work. Within this group, Albena Mihovska and Filippo Meucci were real motivators and mentors for one of the best contributions from my thesis. I also do not forget Dorthe Sparre who helped me on settling in Aalborg, Denmark. To Instituto de Telecomunicações (IT) and Universidade da Beira Interior (UBI), I would like to acknowledge the excellent lodging and outstanding working conditions. IT and UBI supported my attendance to research meetings and conferences, essential for my research and to divulg