26.2363GPPPacket switched conversational multimedia applicationsTransport protocolsTS
3G PS multimedia terminals provide real-time video, audio, SES or data, in any combination, including none, over 3GPP IM Subsystem. Terminals are based on IETF defined multimedia protocols SIP, SDP, RTP and RTCP. Communication may be either 1-way or 2-way. Such terminals may be part of a portable device or integrated into an automobile or other non-fixed location device. They may also be fixed, stand-alone devices; for example, a video telephone or kiosk. Multimedia terminals may also be integrated into PCs and workstations.
In the case of SES then uplink communication is from the terminal to a server containing speech recognition.
The transmission and reception of audio in Push-to-Talk over Cellular (PoC) communication is controlled by a RTCP APP conveyed Talk Burst Control Protocol defined in OMA PoC User Plane Version 1 .
In addition, interoperation with other types of multimedia telephone terminals, such as 3G-324M may be possible, however in such case a media gateway functionality supporting 3G-324M – IM Subsystem interworking will be required within or outside the IM subsystem.
Figure 1 presents the user plane protocol stack of a 3G PS conversational multimedia terminal explaining the transport of different media types and QoS reports.
Figure 1 – User plane protocol stack for 3G PS conversational multimedia terminal