Study on access traffic steering, switching and splitting support in the 5G system architecture; Phase 3
The purpose of this Technical Report is to enhance the ATSSS feature by investigating solutions that can support the following capabilities:
1) Support new steering functionalities that can steer/switch/split non-TCP traffic flows (e.g. UDP traffic flows and IP traffic flows). Two types of such steering functionalities are studied: (i) a steering functionality based on the QUIC protocol and its multipath extensions, and (ii) a steering functionality based on the DCCP protocol and its multipath extensions.
2) Support redundant traffic steering for both GBR and non-GBR traffic flows. With redundant traffic steering, a traffic flow (GBR or non-GBR) can be replicated on multiple access paths and, therefore, can improve transmission reliability and reduce packet latency.
3) Support traffic switching between one non-3GPP access path, from a UE to a N3IWF in a PLMN, and another non-3GPP access path, from the UE to a TNGF in the same PLMN.
4) Support the establishment of a MA PDU Session with one 3GPP access path via 5GC and one non-3GPP access path via ePDG/EPC. This is to complement the existing ATSSS capability that supports the establishment of a MA PDU Session with one non-3GPP access path via 5GC and one 3GPP access path via EPC.
For each of the above capabilities, the conclusions of the study identify whether a solution is required for the normative phase and, if required, which solution to consider in the normative phase.