A.2 DASH Media Presentation Delivery

26.3483GPPNorthbound Application Programming Interface (API) for Multimedia Broadcast/Multicast Service (MBMS) at the xMB reference pointRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

A.2.1 Introduction

This clause illustrates the various xMB-U options for DASH Media Presentation delivery. A DASH Media Presentation consists of a Media Presentation Description (MPD), one or more initialization segments and sequences of media segments, containing the media data. A segment is a small file, containing a defined duration of media time, like 2sec of media time.

The Media Presentation Description (MPD) and Initialization Segments (IS) are typically provided with the SACH before the actual DASH media segment reception so that the UE has all access information available for tuning in to the DASH stream. The media segments and MPD updates are ingested using xMB-U.

A.2.2 DASH Content ingestion with Pull

The Content Provider delegates all MBMS related complexity to the operator and provides DASH compliant content using HTTP to the BM-SC. The Content Provider provides a MPD to the BM-SC and the BM-SC fetches the DASH content according to the MPD description using HTTP. The BM-SC is handling all MBMS related complexity, e.g. converting the HTTP payload into an IP Multicast suitable protocols, adding AL-FEC, etc. The Content Provider delegates the delivery of MBMS of Service Announcement Metadata (i.e. DASH MPD, IP Multicast protocol details, etc) to the MBMS Client to the BM-SC.

Figure A.2.2-1 illustrates a setup, where the BM-SC fetches DASH Content using HTTP GET according to an DASH MPD from a Content Server.

Figure A.2.2-1: Segment Delivery using Pull Mode (HTTP GET)

The following Session Properties allow the configuration of this xMB-U mode.

– Session Type is set by the Content Provider to Application.

– Ingest Mode (Session Type specific property) is set by the Content Provider to Pull.

– Application Service Description (Session Type specific property) is set to application/dash+xml.

– Application Entry Point URL contains the URL to the DASH MPD. The BM-SC will fetch the DASH MPD using the value of the Application Entry Point URL and start fetching segments. Further, the BM-SC will fetch the DASH MPD using the value of the Application Entry Point URL and embed the MPD into the Service Announcement File (SACH).

– Unicast Delivery is set to false. Indicating that the operation is not allowed to use MooD, e.g. because of content distribution rights.

Procedure

The following flow diagram illustrates the message flow. During provisioning phase, the according xMB Service and Sessions are created. Some lead time is needed to secure that all intended receiving UEs are capable of receiving the content.

Figure A.2.2-2: Call Flow

Provisioning

1: The Content Provider creates the DASH Delivery Service and Session using xMB procedures.

2: As result of the Service and Session provisioning procedure, the Content provider gets the service identification information, which needs to be used by the App to request the reception activation from the MBMS Client.

3: The content provider provides the MPD and IS, which should be provided together with other access information using the SACH to the MBMS Client.

4: The MBMS client receives the service access information. At scheduled DASH Session start time.

5: The BM-SC updates the MPD according to the MPD update instructions.

6: The BM-SC uses the provided MPD to determine the segment availability start times for the different segments. Here, Segment X is the next segment to send and the BM-SC segments a segment request to the Content Provider.

7: The BM-SC receives the requested Segment X and wraps it into MBMS Download Delivery Objects.

8: The BM-SC sends the DASH Segment as MBMS Download Delivery Object.

9: Steps 5 to 8 are repeated for every DASH media segment until the session schedule end time is reached.

A.2.3 DASH Content ingestion with Push

The Content Provider delegates all MBMS related complexity to the operator and provides DASH compliant content using HTTP to the BM-SC. The Content Provider pushes the DASH Content as soon as new DASH Content is available using HTTP. The BM-SC is handling all MBMS related complexity, e.g. converting the HTTP payload into an IP Multicast suitable protocols, adding AL-FEC, etc.The Content Provider delegates the delivery of MBMS of Service Announcement Metadata (i.e. DASH MPD, IP Multicast protocol details, etc) to the MBMS Client to the BM-SC.

Figure A.2.3-1 illustrates a setup, where a DASH packager pushes DASH Content using HTTP PUT into the BM-SC, once the segment (or MPD update) becomes available.

Figure A.2.3-1: DASH Content Delivery using Push (HTTP PUT)

The following Session Properties allow the configuration of this xMB-U mode.

– Session Type is set by the Content Provider to Application.

– Ingest Mode (Session Type specific property) is set by the Content Provider to Push.

– The BM-SC provides the Push URL (Session Type specific property) to the Content Provider. The value of this property is configured to the DASH packager.

– Application Service Description (Session Type specific property) is set to application/dash+xml.

– Application Entry Point URL contains the URL to the DASH MPD. The BM-SC will fetch the DASH MPD using the value of the Application Entry Point URL and embed the MPD into the Service Announcement File (SACH).

– Unicast Delivery is set to false. Indicating that the operation is not allowed to use MooD, e.g. because of content distribution rights.

Procedure

Figure A.2.3-2: Call Flow

Provisioning

Steps 1 to 4 are identical as in Figure A.2.2-2.

At scheduled DASH Session start time.

5: The content provider starts pushing DASH media segments to the BM-SC, which wraps the DASH Media Segments into MBMS Download Delivery Objects.

6: The BM-SC sends the File as MBMS Download Delivery Object.

7: Steps 5 and 6 are repeated for every DASH media segment until the session schedule end time is reached.