5G will lay the foundations for the mainstream broadband wireless technology of the next decade, a leverage toward ensuring the efficiency, effectiveness and adaptability of everyday high-demanding operations, such as those in Public Protection and Disaster Relief. The ITU considers LTE-Advanced systems and 5G as a mission critical PPDR technology able to address the needs of MC intelligence, providing support for MC voice, data and video services as an IMT radio interface. In this paper, we introduce 5G-EPICENTRE, an innovation action funded by the EC under the Horizon 2020 research framework, which aims to deliver an open, federated 5G end-to-end experimentation platform specifically tailored to the needs of PPDR software solutions. The envisioned platform will allow SMEs and developers a lower entry barrier to the PPDR market, enabling them to build-up and experiment with their solutions in a cost effective way. The 5G-EPICENTRE platform will be based on an open Service Oriented Architecture and will accommodate open access to 5G networks' resources, acting this way as an open source repository for PPDR 5G Network Applications (NetApps). The purpose of the federated platform is to provide sufficient resources to cover the entire range of the 3 ITU-defined service types (i.e. eMBB, mMTC and URLLC) and to deliver secure interoperability capabilities beyond vendor-specific implementation.