11 Blending of Presence and PSS/MBMS user services

26.2373GPPIP Multimedia Subsystem (IMS) based Packet Switch Streaming (PSS) and Multimedia Broadcast/Multicast Service (MBMS) User ServiceProtocolsRelease 17TS

11.1 General description

This clause describes the mechanisms that apply when IMS based PSS and MBMS user services are combined with presence service.

The architecture and functional description of the presence service when used in relation to the IMS based PSS & MBMS services shall conform to [37].

The protocol details for the presence service when used in relation to the IMS based PSS & MBMS services shall conform to [36].

The following call flow gives a high-level description for presence service used in the context of IMS based PSS and MBMS. In this example, the UE 1 is the watcher and the UE 2 is the presentity. The UE 2 is in the UE 1’s list of contacts and wants to publish on-demand content currently watching.

Figure 26: High-level description for presence service used in the context of IMS based PSS and MBMS

1. The UE 1 subscribes for presence information for a list of contacts which includes the UE 2, by sending a SIP SUBSCRIBE message to the Presence Server as defined in [36].

2. After having initiated the PSS or MBMS session, or after a content switching, the UE 2 decides to publish what content is being consumed. The UE 2 sends a SIP Publish message to the Presence Server, as defined in [36], including additional attributes specific to PSS and MBMS such as the content being consumed.

3. On reception of the SIP Publish, the Presence server notifies the UE 1 of what the UE 2 is doing, by sending a SIP NOTIFY message as defined in [36].

11.2 Procedures at the UE acting as presentity

The UE acting as presentity may send a SIP PUBLISH in the following cases:

– On receipt of a final SIP 200 OK concerning a PSS streaming session initiation procedure;

– On receipt of a final SIP 200 OK concerning a MBMS streaming session initiation procedure;

– On receipt of a final SIP 200 OK concerning a 3GP-DASH session initiation procedure;

– On receipt of a final SIP 200 OK concerning a MBMS download session initiation procedure.

During a streaming session (including DASH-formatted content delivery), the UE may also send a PUBLISH request after having performed content switching. This includes the cases of:

– PSS content switching (for both PSS streaming and 3GP-DASH services),

– MBMS content switching (for both MBMS streaming and MBMS download services),

– Switching from PSS to MBMS streaming with channel change,

– Switching from MBMS to PSS streaming with channel change,

– Switching from 3GP-DASH to MBMS download service with channel change,

– Switching from MBMS download to 3GP-DASH service with channel change.

The content of the PUBLISH request shall be set as follows:

– The request-URI, the To and the From headers shall be set to the public user identity of the user,
– The Event header shall be set to the "presence" event package,
– The content type shall be set to "application/pidf+xml"

The SIP PUBLISH generated by the UE acting as presentity shall conform to [36].

The presence XML document included in the PUBLISH body shall conform to [36] and [37].

Additional elements specific to PSS and MBMS services shall be included in the XML document. In case of a Live TV service, these specific additional elements are the Live TV channel currently watched, and the current TV program. In case of an on-demand service, specific additional element is the on-demand content.

The XML schema used when the presence documents are published by the UE is described in Annex E of [24], with the following conformity:
– the "currentBCServiceID" refers to the LiveTV channel delivered in PSS or MBMS,

– the "currentBCProgramID" refers to the currently watched program delivered in PSS or MBMS,

– the "currentCoDContentID" refers to the currently watched on-demand content delivered in PSS.

11.3 Procedures at the UE acting as watcher

The SIP SUBSCRIBE generated by the UE acting as a watcher shall conform to [36].

The UE acting as a watcher may then receive a SIP NOTIFY message including the content consumed by the UE acting as presentity.