Flexible spectrum usage is a promising enabler of spectral efficiency for next generation wireless broadband networks. In order to deliver the next order of magnitude gains in terms of overall spectral and radio efficiency envisioned for 2020, wireless access will have to be revisited both from a policy as well as from a technology innovation perspective. On the policy side, with the emergence of heterogeneous and small cell networks, the original ''licensed vs. unlicensed''spectrum usage model has recently given way to the ''licensed shared access (LSA)'' paradigm wherein incumbent operators may allow smaller ones to share their spectrum at specific times and places, according to an agreed set of rules. In order to deliver the targeted gains, the LSA approach needs to address specific technology challenges. In ADEL we plan to address the following key challenges within the LSA wireless access paradigm: i) the dynamic and optimised allocation of the spectral and power resources at a short time scale (on the order of seconds to even milliseconds),ii) the guarantee of Quality of Service to the users of all participating spectrum-sharing networks and iii) the minimisation of the overall energy expenditure of LSA networks. As key technology enablers towards these goals, we propose the use of i) decentralised spectrum sharing techniques that allow both faster decision making and less control overhead; ii) advanced collaborative sensing between the cooperating wireless networks and individual nodes for better network coordination; iii) advanced frequency agile transceivers; and iv) self-optimisation techniques at the LSA networks to further minimise the EMF radiation and the interference caused to the incumbent networks. With the above, we believe that ADEL will lead to future heterogeneous wireless networks of an order of magnitude higher capacity and energy efficiency thus setting the roadmap for the adoption of spectrum flexible broadband wireless systems by 2020.