## 3 SATis5 Testbed Architecture
The final version of the SATis5 testbed will consist of two star-shaped backhaul networks, with one satellite hub in Munich and one in Betzdorf. The core network is located in Berlin and is connected to the hub locations via a best effort Internet connection. At each location of the local radio access  
Figure 4: Architecture of the 2018 SATis5 testbed. Figure 5: NSA Option 3 Variants: The initial deployments of 5G services are based on 5G NSA, also called Option 3.  
networks, there is an edge node, satellite modems with outdoor equipment and at least one mobile base station to provide service to the UEs. In this article, we present two testbed demonstrations with different satellite ground segment elements. The main difference between the two designs is that in Setup 2 (Section 5.2) conventional point-to-point satellite modems were deployed because the Newtec Dialog 1 IF satellite hub, which will be utilized in the final testbed, was not installed until this testbed demonstration. This basically means that no control signals are exchanged between the core network and these modems and therefore no management of this equipment is possible for a third party MNO. This setup is comparable to an existing user of satellite communication who wants to offer his communications service to an MNO (e.g., leased line). With Setup 1, however, the iDirect satellite hub and modems offer integration into the overall 5G network architecture, as various concepts such as software defined networking in the Satellite Convergence (Sat Conv) layer are already taken into account in the design of these modems and the satellite hub, which are utilized in a star network topology. For an MNO, this has the advantage that it can manage these modems and the satellite hub in its network by itself. For cost reasons, various business models will be developed for the integration of satellite into a 5G network. The provision of a certain bandwidth via conventional legacy equipment with a guaranteed failure probability as in Setup 2 can also be of importance here, which is why this use case will also be investigated. An overview of the architecture for the testbed demonstration Setup 1 in Section 5.1 is illustrated in Figure 7 and is described in detail thereafter. The satellite ground segment corresponds to the iDirect Velocity Intelligent Gateway (IGW) system residing at the teleport site introduces a standard 3 GPP core network (SatCore) to the satellite hub platform. Functions of the existing satellite network are offloaded, allowing SatCore to operate and manage network as a standard terrestrial 3 GPP network. The existing satellite network is modified to comply standard RAN, referred to as Satellite RAN (SatRAN), node to the SatCore. In addition, the remote satellite terminal is modified to present itself as a standard UE to the network, which allows it to connect to a SatCore in order to access network services. Thus, the existing satellite network has been modified to comply with the standard 3 GPP core network architecture. That is, SatRAN has been modified and Ni interfaces to SatCore have been aligned to the 3 GPP core network. As such, SatRAN presents itself as a standard 3 GPP Cellular RAN, whereas the remote satellite terminal presents itself  
Figure 6: Final terminal deployment for the testbed. as a standard 3 GPP Cellular UE to the network. This enables support for 3 GPP services, such as authentication, billing and policy and charging. This also enables the management of the satellite network by the Mobile Network Operator (MNO) in a seamless way, as if the MNO manages a standard 3 GPP 5G cellular access network. As such, roaming between satellite and terrestrial mobile networks is enabled by such architecture. In fact, the SatCore may be operated by the MNO or the Satellite Network Operator (SNO), depending on the business model, and there may even be separate 3 GPP core networks for the MNO and SNO networks.