TeamUp5G is a European Training Network (ETN) in the frame of the Marie Skłodowska-Curie Innovative Training Networks (MSCA ITN) of the European Commission’s Horizon 2020 framework. With the continuous increase of data rates and the number of people using mobile communications, wireless connections are evolving towards 5G. To fulfill the user satisfaction and a plethora of challenging requirements, pivotal to the evolution towards 5G are the ultra-dense networks (UDN) with small-cells (SCs). Because of the technical limitations/challenges observed in the path of providing seamless like; limited available spectrum, the need to coexist within complex environments of multiple heterogeneous technologies and users, the demand of increasing data rates per km etc. the main technical objectives are: • Design novel PHY/link/MAC algorithms and protocols to enhance capacity and user satisfaction. • Propose new dynamic spectrum management, opportunistic optimization of radio resources and CR techniques, together with self-organization capabilities, with different levels of collaboration. • Devise techniques and methodologies to save energy that make the previously proposed optimization techniques sustainable and environmental friendly. • Develop a proof of concept to demonstrate the feasibility of the proposed innovative techniques and encourage practical deployment, through prototyping and experimental research activities.