The Network Analytics architecture is defined in TS 23.288
In order to support the ATSSS feature, the 5G System Architecture is extended as shown in Figure 4.2.10-1, Figure
4.2.10-2 and Figure 4.2.10-3. The additional functionality that is supported by the UE and the network functions shown
in these figures is specified in clause 5.32
below. In summary:
The UE supports one or more of the steering functionalities specified in clause 5.32.6, e.g. MPTCP functionality and/or ATSSS-LL functionality. Each steering functionality in the UE enables traffic steering, switching and
splitting across 3GPP access and non-3GPP access, in accordance with the ATSSS rules provided by the
network. The ATSSS-LL functionality is mandatory in the UE for MA PDU Session of type Ethernet.
The UPF may support MPTCP Proxy functionality, which communicates with the MPTCP functionality in the UE by using the MPTCP protocol .
The UPF may support ATSSS-LL functionality, which is similar to the ATSSS-LL functionality defined for the UE. There is no user plane protocol defined between the ATSSS-LL functionality in the UE and the ATSSS-LL functionality in the UPF. The ATSSS-LL functionality in the UPF is not shown in the following three figures.
NOTE 1: ATSSS-LL functionality is needed in the 5GC for MA PDU Session of type Ethernet.
In addition, the UPF supports Performance Measurement Functionality (PMF), which may be used by the UE to obtain access performance measurements (see clause 5.32.5) over the user-plane of 3GPP access and/or over the user-plane of non-3GPP access.
The AMF, SMF and PCF are extended with new functionality that is further discussed in clause 5.32.
: The interactions between the UE and PCF that may be required for ATSSS control are specified in TS 23.503
: A UPF that supports the MPTCP Proxy functionality and the PMF can be connected via an N9 reference
point, instead of the N3 reference point.
Figure 4.2.10-2 shows the 5G System Architecture for ATSSS support in a roaming case with home-routed traffic and
when the UE is registered to the same VPLMN over 3GPP and non-3GPP accesses. In this case, the MPTCP Proxy
functionality and the PMF are located in the H-UPF.
Figure 4.2.10-3 shows the 5G System Architecture for ATSSS support in a roaming case with home-routed traffic and
when the UE is registered to a VPLMN over 3GPP access and to HPLMN over non-3GPP access (i.e. the UE is
registered to different PLMNs). In this case, the MPTCP Proxy functionality and the PMF are located in the H-UPF.