The NECOS project addresses the limitations of current cloud computing infrastructures to respond to the demand of new and heterogeneous services. NECOS is driven by use cases that are refined into different scenarios. The proposed solution is based on a new concept – Lightweight Slice Defined Cloud (LSDC) – as an approach that extends the virtualization to all the resources in the involved networks and data centres and provides a uniform management with a high-level of orchestration.