Experimental Integration of Non-5G Capable Devices into 5G Networks via Untrusted WLAN: The Unif Approach

This paper introduces the Untrusted Non-3GPP Interworking Function (UNIF), a novel network function designed to enable devices that do not support the 5G NAS protocol over untrusted non-3GPP access networks to seamlessly connect to a 5G core network. Such devices are referred to as Non-5G Capable over Non-3GPP (N5CN3) devices. UNIF bridges a significant gap in current 3GPP specifications by allowing such devices to utilize untrusted non-3GPP access networks, such as public WLANs, for 5G connectivity. The prototype implementation of UNIF supports single or dual Packet Data Unit (PDU) Sessions per N5CN3 device and dynamic traffic routing for edge and remote data networks. Evaluation results show that UNIF achieves an average connection setup time of 284 ms, downlink throughput of 552 Mbps, and low latency of $18-35 ~\text{ms}$, validating its potential to extend 5G to N5CN3 devices.