3GPP 23.501 v20.2.0 — the document's own text
4.2.8.5.3 Network Functions
Taught in 10. Radio, Wi-Fi, cable — every way in (The 5G system architecture, in depth), 7. Roaming, other accesses, the edge and the outside (The 5G system architecture, overview).
Trusted WLAN Access Point (TWAP): It is a particular type of a Trusted Non-3GPP Access Point (TNAP) specified in clause 4.2.8.2, that supports a WLAN access technology, e.g. IEEE 802.11. This function is outside the scope of the 3GPP specifications.
Trusted WLAN Interworking Function (TWIF): It provides interworking functionality that enables N5CW devices to access 5GC. The TWIF supports the following functions:
- Terminates the N1, N2 and N3 interfaces.
- Implements the AMF selection procedure.
- Implements the NAS protocol stack and exchanges NAS messages with the AMF on behalf of the N5CW device.
- On the user plane, it relays protocol data units (PDUs) between the Yw interface and the N3 interface.
- May implement a local mobility anchor within the trusted WLAN access network.