Content for TS 23.435 Word version: 19.3.0

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9.9 Predictive slice modification in edge based NSCE deployments 9.9.1 General 9.9.2 Procedure 9.9.2.1 Procedures on predictive slice modification in edge based NSCE deployments 9.9.3 Information flows 9.9.4 APIs 9.9.4.1 General 9.9.4.2 SS_NSCE_Service_Continuity_Requirement 9.9.4.3 SS_NSCE_Service_Continuity_Negotiation 9.9.4.4 SS_NSCE_Slice_Modification_Notify
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9.9 Predictive slice modification in edge based NSCE deployments p. 68

9.9.1 General p. 68

In this feature, the NSCE server initially receives an expected/predicted UE location/mobility change request outside an EDN service area for one or more UEs within the VAL application session (e.g. such session can be an indirect V2V session or a multiplayer gaming session). Then, the source NSCE server checks with 5GS (OAM, 5GC) whether the serving slice is available and can offer the same performance at the target EDN. Thereafter, NSCE server evaluates the need for a slice modification (e.g. a slice lifecycle related trigger change) e.g. a slice subnet resource adaptation to allow for optimizing the application performance at the target area. Based on this decision/recommendation, it provides the action to the OAM and supports the re-mapping of NSCE server for the NSCE client proactively, before UE mobility happens.

9.9.2 Procedure p. 68

9.9.2.1 Procedures on predictive slice modification in edge based NSCE deployments p. 68

In the procedure shown in Figure 9.9.2.1-1, a mechanism is provided to allow for slice modification when a vertical application of single or group of VAL UEs migrates (or is expected/predicted to migrate) to a different EDN supported by different NSCE server.

Pre-conditions:

The VAL server has subscribed to the network slice capability enablement server
The VAL client of VAL UE is mapped to Slice#1, and NSCE client of VAL UE has established a connection to NSCE server#1 (S-NSCE server).
The S-NSCE server has already discovered the T-NSCE server and its area of coverage.
The VAL server is subscribed to and received prediction of UE location change.

Reproduction of 3GPP TS 23.435, Fig. 9.9.2.1-1: Support for predictive slice modification in distributed NSCE server deployments

Figure 9.9.2.1-1: Support for predictive slice modification in distributed NSCE server deployments

Step 1.

The VAL server sends to S-NSCE server an application service continuity requirement request due to predicted/expected UE or group UE mobility to a target service area covered by a different EDN.

Step 2.

S-NSCE server sends an application service continuity requirement response to the VAL server as positive or negative acknowledgement.

Step 3.

S-NSCE server determines to query the underlying 3GPP system on the slice availability and conditions at the target service area (based on step 1 requirement). Such query may be in form of a request/response and include:

S-NSCE server interacting with 5GC to query the UE specific information (location, UE connection capabilities) as well as network conditions (network monitoring from NEF) and/or slice related analytics on the slice load (from NWDAF as specified in TS 23.288).
S-NSCE server may also interact with OAM to query on the target slice availability and the up-to-date configured slice parameters e.g. slice RRM policies, modification of the NSI/NSSI resources (see clause 5.1.12 of TS 28.531) at the target service area and measurements for the slice at the target area.

Step 4.

S-NSCE server evaluates whether new NSCE service area supports slice #1 and if slice #1 offers similar performance in target area.

Step 5.

If the current slice doesn't fulfil these requirements, S-NSCE sends to the T-NSCE server (covering the target area) a service continuity negotiation request (including the VAL application service continuity requirement and optionally a proposed action) to negotiate on the trigger action.

Step 6.

T-NSCE server determines the need for a slice lifecycle change at the target area and translates this to a trigger action. This trigger action can be based on the proposed action in step 5 and can be a requested slice modification or the slice #1 creation/instantiation at the target area (this may happen if a group of UEs are moving to the target area and use slice #1, so it may be beneficial to create slice #1 at the target area).

Step 7.

T-NSCE server sends to the S-NSCE server a service continuity negotiation response including the determined trigger action.

Step 8.

The S- or T-NSCE server may send the trigger action as a slice modification trigger request to the slice provisioning MnS producer at OAM (e.g. slice modification for network slice) to extend slice availability to the target service area based on the expected/predicted VAL UE or VAL group mobility. As response to the trigger action, the provisioning MnS producer provides a slice modification trigger response to the corresponding NSCE server with a positive or negative result.

Step 9.

After the slice lifecycle change execution (based on the indication in step 5), the S-NSCE server sends a notification to the VAL server and optionally to the VAL client via S-NSCE client

Step 10.

If the NSCE client needs to be remapped to different NSCE server (due to the expected change of UE location), the NSCE client establishes a new connection with T-NSCE and terminates the one with S-NSCE (in case of subscription-based interaction), or in case of request-based interaction, it updates the mapping at the client side, and maintains the new NSCE server address / ID for the target NSCE area.

9.9.3 Information flows p. 70

9.9.3.1 General p. 70

The following information flows are specified for the predictive slice modification support based on clause 9.9.2.

9.9.3.2 Application service continuity requirement request p. 70

Table 9.9.3.2-1 describes information elements for the Application service continuity requirement request from the VAL server to the NSCE server.

Table 9.9.3.2-1: Application service continuity requirement request

Information element	Status	Description
VAL server ID	M	The identifier of the VAL server.
Security credentials	M	Security credentials resulting from a successful authorization.
VAL service ID	M	The identifier of the VAL service for which the requirement request applies.
VAL UE ID list	O	The list of VAL UE IDs for which the requirement request applies.
Service Continuity Requirement	M	The service continuity requirement which can be the expected or predicted migration of the VAL application or a list of VAL UEs within the application to a target area.
Slice identifier	O	The slice identifier (S-NSSAI, NSI ID or ENSI) which is mapped to the VAL application, if known by the VAL server.
Target Service Area	O	The target area can be represented as the geographical coordinates / set of waypoints outside the original service area, where the VAL application/ UE(s) is expected or predicted to move.
Application QoS requirements	O	The QoS requirements / KPIs for the VAL service.

9.9.3.3 Application service continuity requirement response p. 70

Table 9.9.3.3-1 describes information elements for the Application service continuity requirement response from the NSCE server to the VAL server.

Table 9.9.3.3-1: Application service continuity requirement response

Information element	Status	Description
Result	M	The result of the request (positive or negative acknowledgement).

9.9.3.4 Service continuity negotiation request p. 71

Table 9.9.3.4-1 describes information elements for the service continuity negotiation request from the S-NSCE server to the T-NSCE server.

Table 9.9.3.4-1: service continuity negotiation request

Information element	Status	Description
S-NSCE server ID	M	The identifier of the source NSCE server.
VAL service ID	M	The identifier of the VAL service for which the request applies.
VAL UE ID list	O	The list of VAL UE IDs for which the request applies.
Service Continuity Requirement	M	The service continuity requirement which can be the expected or predicted migration of the VAL application or a list of VAL UEs within the application to a target area.
Proposed Trigger Action	O	The proposed slice licecycle change for the target VAL UE or VAL application.
Slice identifier	M	The slice identifier (S-NSSAI, NSI ID or ENSI) which is mapped to the VAL application, if known by the VAL server.
Application QoS requirements	O	The QoS requirements / KPIs for the VAL service.

9.9.3.5 Service continuity negotiation response p. 71

Table 9.9.3.5-1 describes information elements for the service continuity negotiation response from the T-NSCE server to the S-NSCE server.

Table 9.9.3.5-1: service continuity negotiation response

Information element	Status	Description
Result	M	The result of the request (positive or negative acknowledgement).
Trigger Action	O	The determined trigger action which can be the slice licecycle change for the target VAL UE or VAL application.

9.9.3.6 Slice modification notify p. 71

Table 9.9.3.6-1 describes information elements for the slice modification notify message from the NSCE server to the VAL server or the VAL client (via NSCE client).

Table 9.9.3.6-1: slice modification notify

Information element	Status	Description
VAL service ID	M	The identifier of the VAL application which is expected to be impacted by the slice modification.
VAL UE ID list	O	The identifiers of the VAL UEs which are expected to be impacted by the slice modification.
Slice identifier	M	The slice identifier (S-NSSAI, NSI ID or ENSI) which is expected or predicted to modify to extend slice availability to the target service area.
Target NSCE server ID and address	M	The identifier and address of the target NSCE server.
Target Service Area	M	The target area can be represented as the edge service area (including the target DNN/DNAI) or the topological area (e.g. list of cells/TAs) for which the slice modification applies.

9.9.4 APIs p. 72

9.9.4.1 General p. 72

Table 9.9.4.1-1 illustrates the NSCE APIs for the predictive slice modification support feature.

Table 9.9.4.1-1: List of APIs for the predictive slice modification support feature

API Name	API Operations	Known Consumer(s)	Communication Type
SS_NSCE_Service_Continuity_Requirement	Service_Continuity_Requirement	VAL server	Request / Response
SS_NSCE_Service_Continuity_Negotiation	Service_Continuity_Negotiation	NSCE server	Request / Response
SS_NSCE_Slice_Modification_Notify	Slice_Modification_Notify	VAL server or VAL client	Notify

9.9.4.2 SS_NSCE_Service_Continuity_Requirement p. 72

9.9.4.2.1 General p. 72

API description:

This API enables the VAL server to communicate with the network slice capability enablement server for requesting a service continuity requirement over NSCE-S.

9.9.4.2.2 Service_Continuity_Requirement p. 72

API operation name:

Service_Continuity_Requirement

Description:

Providing for Service_Continuity_Requirement to the NSCE server and receiving a response / result.

Known Consumers:

VAL server.

Inputs:

See Table 9.9.3.2-1

Outputs:

See Table 9.9.3.3-1

9.9.4.3 SS_NSCE_Service_Continuity_Negotiation p. 72

9.9.4.3.1 General p. 72

API description:

This API enables the S-NSCE server to communicate with the T-SNCE server for requesting a service continuity negotiation over NSCE-X.

9.9.4.3.2 Service_Continuity_Negotiation p. 73

API operation name:

Service_Continuity_ Negotiation

Description:

Providing for Service_Continuity_ Negotiation to the T-NSCE server and receiving a response / result.

Known Consumers:

S-NSCE server.

Inputs:

See Table 9.9.3.4-1

Outputs:

See Table 9.9.3.5-1

9.9.4.4 SS_NSCE_Slice_Modification_Notify p. 73

9.9.4.4.1 General p. 73

API description:

This API enables the network slice capability enablement server to communicate with the VAL server or VAL UE (NSCE client or VAL client) for notifying the slice modification to extend to the target service area.

9.9.4.4.2 Slice_Modification_Notify p. 73

API operation name:

Slice_Modification_Notify

Description:

Notifying about the slice modification to extend to the target area.

Known Consumers:

VAL server.

Inputs:

See Table 9.9.3.6-1

Outputs:

None