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Fraunhofer FOKUS' Open6GCore is the first practical implementation of a 6G core network. It challenges the traditional view of network functions as rigidly connected components, by embracing a highly modular software-driven approach that offers significant adaptability and reduced complexity. The flexibility of Open6GCore allows dynamic adaptation to requirements, whether as a 5G core network, simplified microservices, microcore, or a distributed large-scale core network. By implementing 3GPP standards with modern IT methodologies, Open6GCore achieves scalability and resilience and simplifies the addition of experimental features. Thus, it is particularly well-suited for research environments, facilitating rapid prototyping and seamless integration of new functionalities. Initial functional validation demonstrates successful deployment, interoperability with 5G User Equipment and Radio Access Networks, and efficient core network operations. These results demonstrate Open6GCore's readiness as a platform for 5G and 6G testbeds, trials, and innovation. This paper highlights the architecture, development, validation, and integration techniques of Open6GCore, offering insight into its role as a foundational platform for next-generation networks.

With software-only core networks, a new level of flexibility has been achieved in how network services can be distributed and where they can be deployed. The 6 G network is foreseen to become increasingly heterogeneous regarding compute resources and their interconnectivity by incorporating new deployments such as fixed and nomadic campus networks, onpremise edge networks, and non-terrestrial networks. In this new environment, service placement is one of the key mechanisms to improve the system's response time, performance, resource utilization, scalability, and robustness. This paper presents a study on network service placement for 6G networks, employing MixedInteger Programming (MIP) and Multi-Criteria Optimization (MCO) for efficient resource allocation. We propose two MIP models addressing minimizing latency, installation costs, and maximizing success rate. Our models evaluate network service placement considering constraints such as node capacities, link bandwidth, and failure scenarios. Numerical results demonstrate the scalability and effectiveness of our approaches, providing insights into optimal network service deployment strategies for future 6G-ready networks.

To enable seamless 5G service continuity for mobile ground users traversing infrastructure-limited or obstructed regions, the integration of Non-Terrestrial Networks based on Low Earth Orbit satellite constellations is being actively pursued. However, the mobility dynamics of ground terminals frequently result in sudden Line-of-Sight loss, which undermines the feasibility of conventional handover preparation involving context transfer, synchronization, and identity continuity. Without pre-coordination, such transitions lead to uplink blindness, session interruption, and degraded performance. This paper addresses the handover problem under Non-Terrestrial Network-specific constraints by (i) defining a structured taxonomy of service continuity mechanisms suited for impaired Line-of-Sight conditions, (ii) introducing an analytical model that captures handover delay, authentication feasibility, and buffer dimensioning under varying visibility regimes, and (iii) quantitatively evaluating these mechanisms in a high-mobility highway scenario. The results underline that while context mirroring ensures superior continuity under full coordination, handover with reactive preparation emerges as the most practical and resilient fallback under constrained Non-Terrestrial-Networks conditions.

In the context of healthcare for elderly patients, especially in areas located far from rehabilitation clinics, pro-viding remotely assisted prevention and treatment enabled by reliable and secure connectivity through micro-networks based on technologies like 5G and beyond, could be a viable alternative to regularly transporting the elderly to the clinics, potentially improving their quality of life. This paper analyses the needs of such a system featuring fall detection and risk assessment as well as rehabilitation at home and presents the design of the End-to- End interoperable and secure software system and the planned validation.

With the accelerating development and deployment of 5G Non-Public Networks (NPNs), many customized and private networks, providing services to local users and devices, are being installed across the world. To fully use the capacity of these networks, their services should also be reachable from other locations outside their limited coverage area. The only solution provided by 5G and beyond-5G 3GPP standardization at the current moment is based on roaming interfaces, which presumes that the NPN operator makes costly and complex peering roaming agreements with many different large scale and NPN operators. This article proposes an alternative to the roaming mechanism based on an Over-The-Top (OTT) peering approach. Similar to the non-3GPP integration, the connectivity in the visited network is transparently used to establish a binding with the home domain. Furthermore, the proposed architecture is implemented and evaluated in a basic form using Fraunhofer 5G Playground, a comprehensive 5G testbed network using commercial base stations and the Fraunhofer Open5GCore in conjunction with standard Android OS devices. Showing that such a solution represents a cost-effective, reduced functionality and relatively easy to implement solution outperforming the roaming approach in both dynamicity and ease of management.

Standardisation, research and development efforts for the fifth generation (5G) of mobile telecommunication networks are well under way. Software Defined Networking (SDN) and Network Function Virtualisation (NFV) are two of the key enabling technologies, considered in these efforts. The need for a flexible, high performant and efficient architecture is well established. Network slicing, which combines SDN and NFV, can contribute to such an architecture. It allows the parallel deployment of differing network stacks on top of any physical infrastructure. SDN's separation of control and data plane components allows for flexible deployments. How can SDN's flexibility be leveraged in a sliced, 5G network infrastructure? There needs to be an efficient way to integrate SDN into 5G networks. In this paper, we posit a way of integration, which allows decoupling the data plane components from any particular control plane. This can improve flexibility, utilisation and extensibility. We envision utilising an SDN switch implementation as the User Plane Function (UPF), and introducing an SDN controller between Session Management Function (SMF) and UPF, to effectively decouple the two. Based on this decoupling, control and data plane components can be deployed in separatelyand new slice orchestration opportunities can be developed. Furthermore, we can leverage deep data plane programmability, to enhance the system in terms of function and flexibility.