Architecture enhancements for non-3GPP accesses
This document specifies the stage 2 service description for providing IP connectivity using non-3GPP accesses to the Evolved 3GPP Packet Switched domain. In addition, for E-UTRAN and non-3GPP accesses, the specification describes the Evolved 3GPP PS Domain where the protocols between its Core Network elements are IETF-based.
ITU-T Recommendation I.130 [2] describes a three-stage method for characterisation of telecommunication services, and ITU-T Recommendation Q.65 [3] defines stage 2 of the method.
The specification covers both roaming and non-roaming scenarios and covers all aspects, including mobility between 3GPP and non 3GPP accesses, policy control and charging, and authentication, related to the usage of non-3GPP accesses.
TS 23.401 [4] covers architecture aspects common to the Evolved 3GPP Packet Switched domain.
The procedures defined in the present document for WLAN access selection and PLMN selection replace the corresponding I-WLAN procedures specified in TS 23.234 [5].
Interworking with 5GS is only supported for untrusted non-3GPP access using GTP-based S2b. Enhancements to support interworking with 5GS are captured in TS 23.501 [87] and TS 23.502 [88].
The WLAN Selection Policy specified in clause 4.8.2.1.6 also covers UEs operating in SNPN access mode as defined in TS 23.501 [87].