Rapid design space exploration with accurate models is necessary to improve designer productivity at the electronic system level. We describe how to use a new event-based design framework, Metro II, to carry out simulation and design space exploration of multi-core architectures. We illustrate the design methodology on a UMTS data link layer design case study with both a timed and untimed functional model as well as a complete set of MPSoC architectural services. We compare different architectures (including RTOSes) explored with Metro II and quantify the associated simulation overhead.