8.6 MBS Procedures

37.4833GPPE1 Application Protocol (E1AP)Release 17TS

8.6.1 MBS Procedures for Broadcast

8.6.1.1 BC Bearer Context Setup

8.6.1.1.1 General

The purpose of the BC Bearer Context Setup procedure is to allow the gNB-CU-CP to establish MBS session resources for a broadcast MBS session in the gNB-CU-UP. The procedure uses MBS-associated signalling.

8.6.1.1.2 Successful Operation

Figure 8.6.1.1.2-1: BC Bearer Context Setup procedure: Successful Operation.

The gNB-CU-CP initiates the procedure by sending the BC BEARER CONTEXT SETUP REQUEST message to the gNB-CU-UP. If the gNB-CU-UP succeeds to establish the requested MBS session resources, it replies to the gNB-CU-CP with the BC BEARER CONTEXT SETUP RESPONSE message.

The gNB-CU-UP shall report to the gNB-CU-CP, in the BC BEARER CONTEXT SETUP RESPONSE message, the result of all the requested resources in the following way:

– A list of BC MRBs which are successfully established shall be included in the BC MRB Setup Response List IE;

– A list of BC MRBs which failed to be established shall be included in the BC MRB Failed List IE;

– For each established BC MRB, a list of MBS QoS Flows which are successfully established shall be included in the MBS QoS Flow Setup List IE;

– For each established BC MRB, a list of MBS QoS Flows which failed to be established shall be included in the MBS QoS Flow Failed List IE.

When the gNB-CU-UP reports the unsuccessful establishment of a BC MRB or MBS QoS Flow the cause value should be precise enough to enable the gNB-CU-CP to know the reason for the unsuccessful establishment.

If the Requested Action for Available Shared NG-U Termination IE in the BC Bearer Context To Setup IE in the BC BEARER CONTEXT SETUP REQUEST message is set to

– "apply available configuration" and an appropriate Shared NG-U Termination is available, the gNB-CU-UP shall apply the radio bearer configuration of the Shared NG-U Termination, and indicate in the BC BEARER CONTEXT SETUP RESPONSE message within the Available BC MRB Configuration IE in the BC Bearer Context To Setup Response IE the radio bearer configuration of the Shared NG-U Termination, if the radio bearer configuration of the Shared NG-U Termination is different than the one requested by the gNB-CU-CP.

– "apply requested configuration" the gNB-CU-UP shall make use of an available appropriate Shared NG-U Termination if the radio bearer configuration of the Shared NG-U Termination, is the same as the one requested by the gNB-CU-CP, otherwise allocate separate resources as requested by the gNB-CU-CP and indicate in the BC BEARER CONTEXT SETUP RESPONSE message within the Available BC MRB Configuration IE in the BC Bearer Context To Setup Response IE the radio bearer configuration of the Shared NG-U Termination.

– "apply available configuration if same as requested" the gNB-CU-UP shall make use of an available appropriate Shared NG-U Termination only if the radio bearer configuration of the Shared NG-U Termination is the same as the one requested by the gNB-CU-CP and reply with BC BEARER CONTEXT SETUP RESPONSE message.

8.6.1.1.3 Unsuccessful Operation

Figure 8.6.1.1.3-1: BC Bearer Context Setup procedure: Unsuccessful Operation.

If the gNB-CU-UP cannot establish the requested resources for the MBS session, it shall consider the procedure as failed and respond with the BC BEARER CONTEXT SETUP FAILURE message and an appropriate cause value.

If the Requested Action for Available Shared NG-U Termination IE in the BC Bearer Context To Setup IE in the BC BEARER CONTEXT SETUP REQUEST message is set to "apply available configuration if same as requested" and the requested configuration does not match the available shared NG-U termination, the gNB-CU UP shall reply with BC BEARER CONTEXT SETUP FAILURE message.

8.6.1.1.4 Abnormal Conditions

void.

8.6.1.2 BC Bearer Context Modification (gNB-CU-CP initiated)

8.6.1.2.1 General

The purpose of the gNB-CU-CP initiated BC Bearer Context Modification procedure is to allow the gNB-CU-CP to modify MBS session resources for a broadcast MBS session. The procedure uses MBS-associated signalling.

8.6.1.2.2 Successful Operation

Figure 8.6.1.2.2-1: BC Bearer Context Modification procedure, gNB-CU-CP initiated: Successful Operation.

The gNB-CU-CP initiates the procedure by sending the BC BEARER CONTEXT MODIFICATION REQUEST message to the gNB-CU-UP. If the gNB-CU-UP succeeds to perform at least partially the requested modifications it replies to the gNB-CU-CP with the BC BEARER CONTEXT MODIFICATION RESPONSE message.

The gNB-CU-UP shall report to the gNB-CU-CP, in the BC BEARER CONTEXT MODIFICATION RESPONSE message, the result of all the requested MBS session resources in the following way:

– A list of BC MRBs which are successfully established or modified shall be included in the BC MRB Setup or Modify Response List IE;

– A list of BC MRBs which failed to be established or modified shall be included in the BC MRB Failed List IE;

– For each newly established or modified BC MRB, a list of MBS QoS Flows which are successfully established or modified shall be included in the MBS QoS Flow Setup List IE;

– For each newly established or modified BC MRB, a list of MBS QoS Flows which failed to be established or modified shall be included in the MBS QoS Flow Failed List IE.

When the gNB-CU-UP reports the unsuccessful establishment of a BC MRB or MBS QoS Flow the cause value should be precise enough to enable the gNB-CU-CP to know the reason for the unsuccessful establishment.

If the BC Bearer Context NG-U TNL Info at 5GC To Setup or Modify IE is contained in the BC BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the previously received BC Bearer Context NG-U TNL Info at 5GC.

8.6.1.2.3 Unsuccessful Operation

Figure 8.6.1.2.3-1: BC Bearer Context Modification procedure, gNB-CU-CP intiated: Unsuccessful Operation.

If the gNB-CU-UP cannot successfully perform any of the requested modifications, it shall respond with a BC BEARER CONTEXT MODIFICATION FAILURE message and an appropriate cause value.

8.6.1.2.4 Abnormal Conditions

void.

8.6.1.3 BC Bearer Context Modification Required

8.6.1.3.1 General

The purpose of the gNB-CU-UP initiated BC Bearer Context Modification Required procedure is to allow the gNB-CU-UP to request the gNB-CU-CP to initiate the modification MBS session resources for a broadcast MBS session and inform the gNB-CU-CP. The procedure uses MBS-associated signalling.

8.6.1.3.2 Successful Operation

Figure 8.6.1.3.2-1: BC Bearer Context Modification Required procedure, gNB-CU-UP initiated: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the BC BEARER CONTEXT MODIFICATION REQUIRED message to the gNB-CU-CP. The gNB-CU-CP replies to the gNB-CU-UP with the BC BEARER CONTEXT MODIFICATION CONFIRM message.

8.6.1.3.3 Abnormal Conditions

void.

8.6.1.4 BC Bearer Context Release (gNB-CU-CP initiated)

8.6.1.4.1 General

The purpose of the gNB-CU-CP initiated BC Bearer Context Release procedure is to allow the gNB-CU-CP to command the release of MBS session resources for a broadcast MBS Session. The procedure uses MBS-associated signalling.

8.6.1.4.2 Successful Operation

Figure 8.6.1.4.2-1: MC Bearer Context Release procedure: Successful Operation.

The gNB-CU-CP initiates the procedure by sending the BC BEARER CONTEXT RELEASE COMMAND message to the gNB-CU-UP.

Upon reception of the BC BEARER CONTEXT RELEASE COMMAND message, the gNB-CU-UP shall release all related signalling and user data transport resources and reply with the BC BEARER CONTEXT RELEASE COMPLETE message.

8.6.1.4.3 Abnormal Conditions

Not applicable.

8.6.1.5 BC Bearer Context Release Request (gNB-CU-UP initiated)

8.6.1.5.1 General

The purpose of the BC Bearer Context Release Request procedure is to allow the gNB-CU-UP to request the gNB-CU-CP to trigger the release of MBS session resources for a broadcast MBS Session. The procedure uses MBS-associated signalling.

8.6.1.5.2 Successful Operation

Figure 8.6.1.5.2-1: BC Bearer Context Release Request procedure: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the BC BEARER CONTEXT RELEASE REQUEST message to the gNB-CU-CP.

Interactions with gNB-CU-CP intitiated BC Bearer Context Release procedure:

Upon reception of the BC BEARER CONTEXT RELEASE REQUEST message the gNB-CU-CP should initiate the BC Bearer Context Context Release procedure.

8.6.1.5.3 Abnormal Conditions

Not applicable.

8.6.2 MBS Procedures for Multicast

8.6.2.1 MC Bearer Context Setup

8.6.2.1.1 General

The purpose of the MC Bearer Context Setup procedure is to allow the gNB-CU-CP to establish MBS session resources for a multicast MBS session in the gNB-CU-UP. The procedure uses MBS-associated signalling.

8.6.2.1.2 Successful Operation

Figure 8.6.2.1.2-1: MC Bearer Context Setup procedure: Successful Operation.

The gNB-CU-CP initiates the procedure by sending the MC BEARER CONTEXT SETUP REQUEST message to the gNB-CU-UP. If the gNB-CU-UP succeeds to establish the requested MBS session resources, it replies to the gNB-CU-CP with the MC BEARER CONTEXT SETUP RESPONSE message.

The gNB-CU-UP shall report to the gNB-CU-CP, in the MC BEARER CONTEXT SETUP RESPONSE message, the result of all the requested resources in the following way:

– A list of MC MRBs which are successfully established shall be included in the MC MRB Setup Response List IE;

– A list of MC MRBs which failed to be established shall be included in the MC MRB Failed List IE;

– For each established MC MRB, a list of MBS QoS Flows which are successfully established shall be included in the MBS QoS Flow Setup List IE;

– For each established MC MRB, a list of MBS QoS Flows which failed to be established shall be included in the MBS QoS Flow Failed List IE.

When the gNB-CU-UP reports the unsuccessful establishment of a MC MRB or MBS QoS Flow the cause value should be precise enough to enable the gNB-CU-CP to know the reason for the unsuccessful establishment.

If the Requested Action for Available Shared NG-U Termination IE in the MC Bearer Context To Setup IE in the MC BEARER CONTEXT SETUP REQUEST message is set to

– "apply available configuration" and an appropriate Shared NG-U Termination is available, the gNB-CU-UP shall apply the radio bearer configuration of the Shared NG-U Termination, and indicate in the MC BEARER CONTEXT SETUP RESPONSE message within the Available MC MRB Configuration IE in the MC Bearer Context To Setup Response IE the radio bearer configuration of the Shared NG-U Termination, if the radio bearer configuration of the Shared NG-U Termination is different than the one requested by the gNB-CU-CP.

– "apply requested configuration" the gNB-CU-UP shall make use of an available appropriate Shared NG-U Termination if the radio bearer configuration of the Shared NG-U Termination, is the same as the one requested by the gNB-CU-CP, otherwise allocate separate resources as requested by the gNB-CU-CP and indicate in the MC BEARER CONTEXT SETUP RESPONSE message within the Available MC MRB Configuration IE in the MC Bearer Context To Setup Response IE the radio bearer configuration of the Shared NG-U Termination.

– "apply available configuration if same as requested" the gNB-CU-UP shall make use of an available appropriate Shared NG-U Termination only if the radio bearer configuration of the Shared NG-U Termination is the same as the one requested by the gNB-CU-CP and reply with MC BEARER CONTEXT SETUP RESPONSE message.

8.6.2.1.3 Unsuccessful Operation

Figure 8.6.2.1.3-1: MC Bearer Context Setup procedure: Unsuccessful Operation.

If the gNB-CU-UP cannot establish the requested MBS session resources for the multicast MBS session, it shall consider the procedure as failed and respond with the MC BEARER CONTEXT SETUP FAILURE message and an appropriate cause value.

If the Requested Action for Available Shared NG-U Termination IE in the MC Bearer Context To Setup IE in the MC BEARER CONTEXT SETUP REQUEST message is set to "apply available configuration if same as requested" and the requested configuration does not match the available shared NG-U termination, the gNB-CU UP shall reply with MC BEARER CONTEXT SETUP FAILURE message.

8.6.2.1.4 Abnormal Conditions

void.

8.6.2.2 MC Bearer Context Modification (gNB-CU-CP initiated)

8.6.2.2.1 General

The purpose of the gNB-CU-CP initiated MC Bearer Context Modification procedure is to allow the gNB-CU-CP to modify MBS session resources for a multicast MBS session. The procedure uses MBS-associated signalling.

8.6.2.2.2 Successful Operation

Figure 8.6.2.2.2-1: MC Bearer Context Modification procedure, gNB-CU-CP initiated: Successful Operation.

The gNB-CU-CP initiates the procedure by sending the MC BEARER CONTEXT MODIFICATION REQUEST message to the gNB-CU-UP. If the gNB-CU-UP succeeds to perform at least partially the requested modifications it replies to the gNB-CU-CP with the MC BEARER CONTEXT MODIFICATION RESPONSE message.

The gNB-CU-UP shall report to the gNB-CU-CP, in the MC BEARER CONTEXT MODIFICATION RESPONSE message, the result of all the requested resources in the following way:

– A list of MC MRBs which are successfully established or modified shall be included in the MC MRB Setup or Modify Response List IE;

– A list of MC MRBs which failed to be established or modified shall be included in the MC MRB Failed List IE;

– For each newly established or modified MC MRB, a list of MBS QoS Flows which are successfully established or modified shall be included in the MBS QoS Flow Setup List IE;

– For each newly established or modified MC MRB, a list of MBS QoS Flows which failed to be established or modified shall be included in the MBS QoS Flow Failed List IE.

When the gNB-CU-UP reports the unsuccessful establishment of a MC MRB or MBS QoS Flow the cause value should be precise enough to enable the gNB-CU-CP to know the reason for the unsuccessful establishment.

If the MC Bearer Context NG-U TNL Info at 5GC IE is contained in the MC BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall update the previously received MC Bearer Context NG-U TNL Info at 5GC.

If the MC Bearer Context NG-U TNL Info at NG-RAN Request IE is contained in the MC BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall include the MC Bearer Context NG-U TNL Info at NG-RAN Modify Response IE in the MC BEARER CONTEXT MODIFICATION RESPONSE message.

If the MRB Progress Information Request Type IE is contained within the MC Forwarding Resource Request IE in the MC BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, include the requested information in the MRB Progress Information IE within the MC Forwarding Resource Response IE in the MC BEARER CONTEXT MODIFICATION RESPONSE message. If the MRB Forwarding Address Request IE set to "true" is contained in the MC Forwarding Resource Request IE in the MC BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, include the MRB Forwarding Address IE within the MC Forwarding Resource Response IE in the MC BEARER CONTEXT MODIFICATION RESPONSE message.

If the MC Forwarding Resource Indication IE is contained in the MC BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, take the included information into account.

If the MC Forwarding Resource Release IE is contained in the MC BEARER CONTEXT MODIFICATION REQUEST message, the gNB-CU-UP shall, if supported, release the indicated MC Forwarding Resource.

8.6.2.2.3 Unsuccessful Operation

Figure 8.6.2.2.3-1: MC Bearer Context Modification procedure, gNB-CU-CP intiated: Unsuccessful Operation.

If the gNB-CU-UP cannot successfully perform any of the requested modifications, it shall respond with a MC BEARER CONTEXT MODIFICATION FAILURE message and an appropriate cause value.

8.6.2.2.4 Abnormal Conditions

void.

8.6.2.3 MC Bearer Context Modification Required (gNB-CU-UP initiated)

8.6.2.3.1 General

The purpose of the gNB-CU-UP initiated MC Bearer Context Modification Required procedure is to allow the gNB-CU-UP to request the gNB-CU-CP to initiate the modification of MBS session resources for a multicast MBS session and inform the gNB-CU-CP. The procedure uses MBS-associated signalling.

8.6.2.3.2 Successful Operation

Figure 8.6.2.3.2-1: MC Bearer Context Modification Required procedure, gNB-CU-UP initiated: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the MC BEARER CONTEXT MODIFICATION REQUIRED message to the gNB-CU-CP. The gNB-CU-CP replies to the gNB-CU-UP with the MC BEARER CONTEXT MODIFICATION CONFIRM message.

If the MC Forwarding Resource Release Indication IE is contained in the MC BEARER CONTEXT MODIFICATION REQUIRED message, the gNB-CU-CP shall, if supported, assume that the indicated MC Forwarding Resource was released by the gNB-CU-UP.

8.6.2.3.3 Abnormal Conditions

void

8.6.2.4 MC Bearer Context Release (gNB-CU-CP initiated)

8.6.2.4.1 General

The purpose of the gNB-CU-CP initiated MC Bearer Context Release procedure is to allow the gNB-CU-CP to command the release of MBS session resources for a multicast MBS Session. The procedure uses MBS-associated signalling.

8.6.2.4.2 Successful Operation

Figure 8.6.2.4.2-1: MC Bearer Context Release procedure: Successful Operation.

The gNB-CU-CP initiates the procedure by sending the MC BEARER CONTEXT RELEASE COMMAND message to the gNB-CU-UP.

Upon reception of the MC BEARER CONTEXT RELEASE COMMAND message, the gNB-CU-UP shall release all related signalling and user data transport resources and reply with the MC BEARER CONTEXT RELEASE COMPLETE message.

8.6.2.4.3 Abnormal Conditions

Not applicable.

8.6.2.5 MC Bearer Context Release Request (gNB-CU-UP initiated)

8.6.2.5.1 General

The purpose of the MC Bearer Context Release Request procedure is to allow the gNB-CU-UP to request the gNB-CU-CP to trigger the release of MBS session resources for a multicast MBS Session. The procedure uses MBS-associated signalling.

8.6.2.5.2 Successful Operation

Figure 8.6.2.5.2-1: MC Bearer Context Release Request procedure: Successful Operation.

The gNB-CU-UP initiates the procedure by sending the MC BEARER CONTEXT RELEASE REQUEST message to the gNB-CU-CP.

Interactions with gNB-CU-CP intitiated MC Bearer Context Release procedure:

Upon reception of the MC BEARER CONTEXT RELEASE REQUEST message the gNB-CU-CP should initiate the MC Bearer Context Context Release procedure.

8.6.2.5.3 Abnormal Conditions

Not applicable.