The renown beyond 3G scenario depicts a diverse wireless networking world of ?network of wireless networks? accommodating a variety of radio technologies and mobile service requirements in a seamless manner. The achievement of this vision raises significant research challenges in view of system coexistence; system scale; network robustness requirements; and evaluation tool design to provide a framework for cost-effective assessment of optimisation algorithms within a heterogeneous system environment. UNITE aims to address the aforementioned research challenges by: a. Implementing an efficient, accurate and scalable Virtual Distributed Testbed (VDT) to support cross-system, and cross-layer optimisation of heterogeneous systems in a unified manner. b. Through the use of the virtual testbed, to investigate, design and evaluate cross-layer and cross-system interactions, between next generation radio and protocols without neglecting important real-system details.