The term "3D network" has emerged from the joint efforts of the academic community, industry and standardization bodies working towards the integration of different network layers to achieve ubiquitous connectivity. As an important milestone, 3GPP standardized the integration of non-terrestrial networks (NTNs) into a terrestrial 5G network under the label 5G-NTN. To create a "fully connected smart world", the vision of 6G further develops the 5G integration approach by aiming for a unified 3D network. This unified 3D network combines technologies from three spatial segments – space, air and ground – into a single, interconnected network.

This position paper of the BMBF project "Open6GHub" describes the activities on unified 3D networks of the German 6G program of the BMBF, underlines the necessity of these R&D activities for Germany and Europe by describing the societal and economic importance of unified 3D networks and reflects both their international embedding in government-funded R&D programs and industrial aspects such as market potential and industrial activities. The paper also highlights the key achievements and results of the Open6GHub activities on RAN and Core topics and naming first steps towards harmonization and consolidation of 3D network use cases and technologies to be provided to 3GPP standardization. Based on this stock of accumulated expertise, future skilled workforce and global impact, examples of R&D elements that need to be addressed in the near future are shown in order to continue the path taken so far towards a successful positioning of the German and European industry on the global 3D network market. This is the only way to guarantee technological sovereignty in 6G technology, which is of central importance for German and European society and the economy.