MBSF: User Service Announcement Channel

[davidjwbbc]

For VIA_MBS_DISTRIBUTION_SESSION mode the MBSF needs to create and manage a special MBS Session with the MB-SMF and a special Distribution Session with an MBSTF. This Distribution Session is a object CAROUSEL operating mode Distribution Session which repeats User Service Announcement Bundles for all advertised User Service Announcements, regardless of MBS User Service.

The User Service Announcement Channel Distribution Session will have a fixed TSI of 1 and a preconfigured MBR and optional preconfigured repetition time for each User Service Announcement Bundle and a preconfigured update interval for the carousel manifest.

Configuration items:

key	description	example
mbr	The MBR for the whole User Service Announcement Channel.	10 Mbps
announcement-repetition-time	Optional repetition time. If specified, adds a repetitionInterval in milliseconds to each ObjectManifest objects entry.	5000
ssm.source-address	The SSM source address that the User Service Announcement Channel will transmit from.	192.168.1.4
ssm.destination-address	The multicast destination address that the User Service Announcement Channel will transmit on.	232.0.0.1
ssm.port	The source and destination UDP port that the User Service Announcement Channel will transmit on.	5000

The DistSession would look something like:

{
	"distSession":	{
		"distSessionId":	"976236ec-d35a-41ef-8575-37171d5304be",
		"distSessionState":	"ACTIVE",
		"mbUpfTunAddr":	{
			"ipv4Addr":	"<udp_tunnel_address>",
			"portNumber":	<udp_tunnel_port>
		},
        "upTrafficFlowInfo": {
		"destIpAddr": { "ipv4Addr": "232.0.0.1" },
                "sourceIpAddr": { "ipv4Addr": "192.168.1.4" },
		"portNumber": 5000
	},
		"mbr":	"10 Mbps",
		"objDistributionData":	{
			"objDistributionOperatingMode":	"CAROUSEL",
			"objAcquisitionMethod":	"PUSH",
			"objAcquisitionIdsPull": ["carousel"]
		}
	}
}

The carousel ObjectManifest would look something like:

{
  "objects": [
    {
      "locator": "http://<mbsf-nmb2-authority>/x-5gmag-service-announcements/v1/user-data-ingest-session/12345678-1234-4234-1234-123456789012",
    },
    {
      "locator": "http://<mbsf-nmb2-authority>/x-5gmag-service-announcements/v1/user-data-ingest-session/87654321-4312-4321-4321-210987654321",
    }
  ]
}

(see #26 for MBS-1/Nmb2 interface details).

[devbbc]

Started implementing this issue

[devbbc]

Implemented methods to read and parse the configuration items to populate internal data structures.

[devbbc]

Initial thoughts on implementing the announcement channel

• Introduce a counter in MBSF. This counter will keep track of the number of User Services that has VIA_MBS_DISTRIBUTION_SESSION as one of its announcement modes.
• When a User Service has VIA_MBS_DISTRIBUTION_SESSION as one of its announcement modes, if it is not already created, the MBSF will create the User Service Announcement Channel.
  • In order to reuse the already implemented mechanics, the MBSF will populate a special User Data Ingest Session with one special MBS Distribution Session Info based on the configuration items. The User Data Ingest Session ID and MBS Distribution Session Info key are set by the MBSF to a statically coded value (e.g. "USER SERVICE ANNOUNCEMENT CHANNEL").
  • The MBSF will then utilise the MBS Distribution Session populated in the above step to create a special MBS Session in the MB-SMF and a special Distribution Session in the MBSTF. If the creation of either the special MBS Session or the special Distribution Session fails, the MBSF will retry after a back-off period using a timer.
• When a User Service Announcement Bundle is available for one of the User Data Ingest Sessions attached to a User Service which has the VIA_MBS_DISTRIBUTION_SESSION as one of its announcement modes, the MBSF will activate the announcement channel.
• When no User Service Announcement Bundles are available for all User Data Ingest Session attached to all User Service which has the VIA_MBS_DISTRIBUTION_SESSION as one of its announcement modes, the MBSF will deactivate the announcement channel.
• When the counter becomes zero, the MBSF deactivates the Distribution Session. This is only deactivation of the MBS Distribution Session and MBS Session and not destruction.

[devbbc]

Introduced data structures and implemented methods to create the User Service Announcement Channel, when a User Service has VIA_MBS_DISTRIBUTION_SESSION as one of its announcement modes.

The MBSF can now populate a special User Data Ingest Session with one special MBS Distribution Session Info based on the configuration items. The User Data Ingest Session ID and MBS Distribution Session Info key are set by the MBSF to USER SERVICE ANNOUNCEMENT CHANNEL".

The UserDataIngSession class is modified to utilise the to create a special MBS Session in the MB-SMF and a special Distribution Session in the MBSTF.

[devbbc]

A sample distSession request sent by the MBSF to the MBSTF for User Service Announcement Channel:

{
  "distSession": {
    "distSessionId": "7ddc58f0-6779-4b5b-936e-c0b733d0a031",
    "distSessionState": "INACTIVE",
    "mbUpfTunAddr": {
      "ipv4Addr": "127.0.0.7",
      "portNumber": 36536
    },
    "upTrafficFlowInfo": {
      "destIpAddr": {
        "ipv4Addr": "232.0.0.1"
      },
      "portNumber": 42172,
      "srcIpAddr": {
        "ipv4Addr": "192.168.1.4"
      },
      "transportSessionId": 1
    },
    "mbr": "10 Mbps",
    "objDistributionData": {
      "objDistributionOperatingMode": "CAROUSEL",
      "objAcquisitionMethod": "PUSH",
      "objAcquisitionIdPush": "carousel"
    }
  }
}

Corresponding response received with objDistributionData.objIngestBaseUrl :

{
  "distSession": {
    "distSessionId": "7ddc58f0-6779-4b5b-936e-c0b733d0a031",
    "distSessionState": "INACTIVE",
    "objDistributionData": {
      "objDistributionOperatingMode": "CAROUSEL",
      "objAcquisitionMethod": "PUSH",
      "objAcquisitionIdPush": "carousel",
      "objIngestBaseUrl": "http://af-mbstf:33637/"
    }
  }
}

[devbbc]

After re-basing my code with latest feature branch of MBSF, implementing functionality to populate the User Service Description JSON object and write it to the file system.

[devbbc]

Re-based code with latest feature branch of MBSF which adds the ability to explicitly set the SSM source IP address and FLUTE TSI (see #31).

[devbbc]

Now implementing functionality to populate the User Service Description JSON object and write it to the file system.

Creating a new class UserServiceAnnBundle to manage the bundle of documents that comprise the composite MBS User Service Announcement associated with a particular MBS User Data Ingest Session. Instances of this new class will spawn a short-lived std::thread to create (or update) a set of files in the local filesystem comprising the bundle to be served by the MBSF over HTTP to the MBSTF via reference point Nmb2 (and later to the MBS Application Provider via reference point MBS-1).

To start with, only the User Service Description JSON object will be populated in the bundle. Later, SDPs will also be included once #32 is complete.