Compared with the instantiation for MTSI-based architecture extension, this instantiation emphasises that the IMS-AGW/MRF may support immersive media processing. It is necessary for 5G EDGAR UEs with poor media capabilities. Figure 6.5.5-1 provides an DCMTSI-based architecture of AR conversational services for EDGAR UE. A 5G EDGAR UE integrated with DCMTSI client in terminal is denoted as an EDGAR-DCMTSI client. An EDGAR-DCMTSI client may request an AR application (i.e., an entry point) via a bootstrap data channel from the data channel server. An EDGAR-DCMTSI client may also generate or retrieve some AR specific data (e.g., pose and viewpoint information) which is transmitted via additional data channels, given that non-media data is handled by using SCTP as specified in IETF RFC 8831. When an EDGAR-DCMTSI client initiates an AR call with another one, the IMS-AGW/MRF with a support of immersive media processing may perform pre-rendering with the media stream originated from the parties of this AR session if they receive the corresponding AR-specific data (i.e. the pose and viewpoint information).
EDGAR-DCMTSI clients negotiate the properties such as reliable or unreliable message transmission, in-order or out-of-order message delivery and an optional protocol for data channel using SDP as defined in IETF RFC 8864. Based on the user plane protocol stack for a basic MTSI client defined in clause 4.2 of TS 26.114 and the Section 6.5 of RFC 8827, all data channels (e.g., both an AR application via bootstrap data channels and AR-specific data via additional data channels) are secured via DTLS.
Furthermore, the IMS-AGW/MRF with a support of immersive media processing are also desirable to 5G STAR UEs due to saving power consumption. Note that the IMS-AGW/MRF with a support of immersive media processing may perform pre-rendering based on the request of the STAR UEs carried in these additional data channels. Particularly, the logical function of immersive media processing may be integrated in the MRF or other media functions.
Figure 6.5.5-2 illustrates the procedure diagram for an immersive AR conversational with two party using EDGAR UEs including an EDGAR-DCMTSI client in the context of the IMS-AGW/MRF with a support of immersive media processing. The procedure is also applicable to establish an immersive AR call where the two parties of a session are STAR UEs or one is STAR UE and the other is EDGAR UE.
The IMS-AGW/MRF composes, renders and encodes the AR immersive media based on the received media stream and the AR-specific data from the originating party, and finally send them to the terminating party.
The IMS-AGW/MRF decodes and pre-renders media stream based on the received media stream from the terminating party and the AR-specific data from the originating party, and finally sends them to the originating party.