The fast technological evolution and the convergence of fixed and mobile communication infrastructures have led to the realization of a large variety of innovative applications and services that have become an integral part of our society. Efficiency, reliability, availability and security, i.e., Quality of Service, are fundamental requirements for these applications. In this framework, performance evaluation and capacity planning play a key role. This paper presents an ongoing research project carried out under the FIRB Programme of the Italian Ministry of Education, Universities and Research. The project addresses basic and foundational research in performance evaluation with the objective of developing new techniques, methodologies and tools for the analysis of the complex systems and applications that drive our society.