Content for TS 23.256 Word version: 17.5.0
5.2.7 UUAA Revocation by USS/UTM
5.2.8 UAV Controller Replacement
5.2.8.1 UAV controller replacement in 5GS
5.2.8.2 UAV controller replacement in EPS
5.2.9 Revocation of C2 Connectivity
5.2.9.1 Revocation of C2 connectivity in 5GS
5.2.9.2 Revocation of C2 connectivity in EPS
5.2.7 UUAA Revocation by USS/UTM p. 45
UAS NF stores the UAV UE's UUAA context after successful UUAA procedure as explained in clause 5.2.2.2 for UUAA-MM and in clause 5.2.3.2 for UUAA-SM procedure.
Step 1.
The USS sends Naf_Authentication_Notification to UAS NF for authorization revocation. The USS includes GPSI, CAA-Level UAV ID, cause of revocation, PDU Session IP address if available in the authorization revocation request.
Step 2.
UAS NF retrieves the UAV UE's stored UUAA context. From the stored UUAA context the UAS NF determines the target AMF or SMF for sending the notification.
Step 3a or 3b.
The UAS NF sends Nnef_Authentication_Notification request to notify the target NF, i.e. either the AMF or the SMF that the UAV is not authorized anymore, indicating the cause is revocation. The target NF shall remove the successful UUAA result and respond to the UAS NF.
Step 4.
The UAS NF shall remove the UAV UE's UUAA context. The UAS NF responds back to the USS indicating that authorization revocation request has been successfully initiated.
Step 5a.
If UAS NF has subscribed to AMF for the Mobility Event Exposure with Event ID = Reachability Filter before, UAS NF unsubscribes to AMF for the mobility event notification by sending Namf_EventExposure_Unsubscribe request with Subscription Correlation ID.
Step 5b.
The AMF acknowledges the un-subscription request from 5a by sending Namf_EventExposure_Unsubscribe response.
Step 6.
If UE is in CM_Idle state, the target NF (i.e. either the AMF or the SMF) initiates the Network Triggered Service Request procedures as described in clause 4.2.3.3 of TS 23.502.
Step 7a.
If the target NF is AMF, the AMF initiates UCU procedure to inform the UE that UUA is revoked. The AMF shall also initiate the release of PDU Sessions related to UAS services.
Step 7b.
If the target NF is AMF, based on network policy the AMF may start network initiated de-registration process as described in clause 4.2.2.3.3 of TS 23.502.
Step 7c.
If the target NF is SMF, the SMF starts network initiated PDU session release process as described in clause 4.3.4 of TS 23.502 to release the associated PDU session.
5.2.8 UAV Controller Replacement p. 46
5.2.8.1 UAV controller replacement in 5GS p. 46
If USS determines that UAV controller replacement is required the USS invokes an Nnef_AFsessionWithQoS_Update service operation to the UAS NF including in the request authorization information (i.e. new pairing information). NEF authorizes the request from the USS followed by interacting with PCF triggering a Npcf_PolicyAuthorization_Update request and provides relevant parameters to the PCF. The PCF uses the information provided by the NEF to derive new PCC rules to allow C2 communication between the UAV and the new UAV controller.
The procedure for UAV-C replacement is as follows:
Step 0.
A UAV has already established user plane connectivity for C2 operation. The USS determines that the UAV-C controlling the UAV needs to be replaced (e.g. if the UAV is misbehaving).
Step 1.
The USS initiates the UAV-C replacement by invoking the Nnef_AFSessionWithQoS_Update request including Transaction Reference ID, UAV-UAVC Pairing info/Flow description(s), QoS reference. See step 1 in clause 4.15.6.6a of TS 23.502, AF session with required QoS update procedure.
Step 2.
NEF authorizes the request from the USS followed by interacting with PCF triggering a Npcf_PolicyAuthorization_Update request and provides relevant parameters to the PCF. PCF determines whether the request is authorized and if the requested QoS is allowed. PCF informs NEF if the request is accepted by invoking Npcf_PolicyAuthorization_Update Response. See Steps 2 - 4 in TS 23.502 Figure 4.15.6.6a-1.
Step 3.
NEF sends a Nnef_AFsessionWithQoS_Update response message (Transaction Reference ID, Result) to the USS. Result indicates whether the request is granted or not. See step 5 in TS 23.502 Figure 4.15.6.6a-1.
Step 4.
Steps 4 - 7 in Figure 5.2.5.4.1-1.
Step 5.
USS invokes the UAV Re-authorization procedure in Figure 5.2.4.3-1 to deliver the new pairing information to the UE. The USS includes the 3GPP UAV ID, the IP address of the PDU session and included in the authorization message the C2 Authorization Result and the C2 Authorization Payload (containing the C2 pairing information containing the new UAV-C identifier and C2 security information) which is further forwarded to the UE.
5.2.8.2 UAV controller replacement in EPS p. 47
The procedure for UAV-C replacement in EPS is as follows:
Step 0.
UAV is attached to EPC with a PDN connection established
Step 1.
The USS determines that the UAV-C controlling the UAV needs to be replaced (e.g. if the UAV is misbehaving).
Step 2.
USS initiates the Nnef_AFSessionWithQoS_Update request including USS Identity/AF Identifier, Transaction Reference ID, UAV-UAVC Pairing info/Flow description(s), QoS reference. Steps 1-3 as in Figure 5.2.7.1-1 takes place.
Step 3.
The PCF determines updated policy information and configures the resources and routing information as in steps 2 - 4 in Figure 5.2.5.4.2-1.
Step 4.
The USS is informed whether the UAV-C replacement and authorization has succeeded or failed as in steps 6- 7 in Figure 5.2.5.4.1-1.
Step 5.
The USS invokes the UAV re-authorization procedure in EPS as in Figure 5.2.4.4-1. The USS includes the 3GPP UAV ID, the IP address of the PDU session and included in the authorization message, the C2 Authorization Result and the C2 Authorization Payload (e.g. containing the C2 pairing information containing the new UAV-C identifier and C2 security information) which is further forwarded to the UE.
5.2.9 Revocation of C2 Connectivity p. 48
5.2.9.1 Revocation of C2 connectivity in 5GS p. 48
When the USS decides to revoke an existing C2 connection between the UAV and UAV-C the USS invokes an Nnef_AFsessionWithQoS_Revoke request to NEF in order to revoke the AF request as described in Figure 5.2.9.1-1.
Step 0.
USS decides to revoke C2 connectivity.
Step 1.
USS identifies the AF session corresponding to the C2 connectivity and invokes an Nnef_AFSessionWithQoS_Revoke Request including USS identity/AF identifier, Transaction Reference ID.
Step 2.
UAS NF/NEF indicates to the PCF to delete the context of application level session information by invoking an Npcf_PolicyAuthorization_Delete request.
Step 3.
The PCF initiates a network requested PDU session modification procedures as in steps 1b-13 in Figure 4.3.3.2-1 of TS 23.502 removing the corresponding PCC rules installed at the SMF to support the AF session or may trigger a network requested PDU session release as in Steps 1b-13 Figure 4.3.4.2-1 of TS 23.502.
Step 4.
The PCF acknowledge the request by sending an Npcf_PolicyAuthorization_Delete response.
Step 5.
The UAS NF/NEF acknowledge the USS request by sending an Nnef_AFSessionWithQoS_Revoke response.
Step 6.
USS may invoke the UAV Re-authorization procedure in Figure 5.2.4.3-1 to deliver a C2 authorization payload indicating that C2 authorization has been revoked.
5.2.9.2 Revocation of C2 connectivity in EPS p. 49
The procedure is as follows:
Step 0.
USS decides to revoke C2 connectivity.
Step 1.
Steps 1 - 2 as described in Figure 5.2.9.1-1 are performed.
Step 2.
The PCF deletes policy information associated with the AF session and configures the resources and routing information as in steps 5 - 6 in Figure 5.2.5.4.2-1.
Step 3.
Steps 4-5 as described in Figure 5.2.9.1-1 are performed.
Step 4.
The USS may invoke the UAV re-authorization procedure in EPS as in Figure 5.2.4.4-1 to deliver a C2 authorization payload indicating that C2 connectivity is revoked.
