Performance evaluation of untrusted non-3GPP Access to a 5G Core Network via satellite

5G is a cornerstone in the evolution of mobile communication networks, representing the most advanced and available standard at the state of art. Characterized by higher data rate and capacity, actually the real revolution of 5G relies in its capability to offer advanced and heterogeneous services by the full abstraction and slicing of network resources, realizing a service-oriented full-IP high-performance network over a common infrastructure, even belonging to different operators. Another key aspect, which is specifically addressed in this paper, is the possibility to access the services offered by the 5G network using non-3GPP access, and in particular Wi-Fi. This feature can allow access from home Access Points or using public Hotspots, even where there is no 5G coverage or roaming. At the same time, other types of IP access, including terrestrial wired options, are allowed by 3GPP specifications. Such a flexibility allows, although not explicitly mentioned, to consider as well satellite-based non-3GPP access methods, thus enabling wide-coverage use-cases and rural areas coverage. In the paper we discuss the network function required to enable non-3GPP access to 5G Core Networks, namely N3IWF, and the impact in using as access network a VSAT satellite link. After a focus on protocol stacks and signalling procedures, we implemented such an access on a real time Linux testbed including a 5G rel. 15 compliant Core Network, a N3IWF network function and a satellite emulation to assess control procedures timings, User plane latency and overhead.