The End-to-End Efficiency (E3) project is an ambitious FP7 EC Integrated Project (IP) aiming at integrating cognitive wireless systems in the Beyond 3G (B3G) world, evolving current heterogeneous wireless system infrastructures into an integrated, scalable and efficiently managed B3G cognitive system framework. The key objective of the E3 project is to design, develop, prototype and showcase solutions to guarantee interoperability, flexibility and scalability between existing legacy and future wireless systems, manage the overall system complexity, and ensure convergence across access technologies, business domains, regulatory domains and geographical regions.Cognitive radio systems are seen by many actors of the wireless industry as a core technical evolution towards exploitation of the full potential of B3G systems. It is under way to revolutionize wireless communications just as the PC revolution. E3 will ensure seamless access to applications and services and exploitation of the full diversity of corresponding heterogeneous systems, in order to offer an extensive set of operational choices to the users, application and service providers, operators, manufacturers and regulators. E3 will optimise the use of the radio resources and spectrum, following cognitive network paradigms. The management functions will be distributed over different network elements at various levels of the system topology.The E3 consortium will bring together major key European players in the domain of cognitive radios and networks, self-management and end-to-end reconfigurability. E3 will build on several key achievements from the successful FP6 E2R Programme, pursuing research into the most promising directions, in order to facilitate the vision of true end-to-end connectivity.The E3 project addresses the core of the Strategic Objective ICT-2007.1.1 "The Network of the Future" from Challenge 1 "Pervasive and Trusted Network and Service Infrastructures".