Intelligent policy rule update

Abstract

Embodiments herein relate to intelligent policy rule updates. In some embodiments, a method (500) performed by a second network function (102) implementing a session management function (SMF) is presented. The method (500) may comprise the step of receiving (S501) a first message from a first network function (101) implementing an access and mobility management function (AMF), the first message comprising a first parameter indicating a first after-retry time. The first after-retry time may instruct the second network function (102) to cease sending a message to a user equipment (UE) (106) before the first after-retry time expires. The method (500) may further comprise transmitting (S502), based on the first message, a second message to a third network function (103) implementing a policy control function (PCF), the second message comprising a second parameter indicative of a second after-retry time during which the UE (106) is deemed not accessible. The embodiments may reduce signal exchange between the PCF and SMF when the UE is not accessible or is busy with other procedures.

Description

Cross-reference to related applications

[0001] This application claims priority to PCT Application Serial No. PCT / CN2022 / 128465, filed on October 30, 2022, entitled "SMARTPOLICYRULE UPDATE", the entire content of which is incorporated herein by reference. Technical Field

[0002] Embodiments herein generally relate to the field of mobile communications, and more particularly, embodiments herein relate to smart policy rule updates. Background Art

[0003] Figure 1 is a schematic block diagram showing an example architecture 100 of a 5G network architecture in a non-roaming scenario. In a 5G network, the packet data unit (PDU) session modification process requested by the network is used when the network initiates a PDU session modification to a user equipment (UE) 106. Figure 2 is a schematic signaling diagram showing messages in an example network-requested PDU session modification. As Figure 2 shown, a policy control function (PCF) 103 may invoke a session management policy control update notification service operation for installing one or more new / modified policy control and charging (PCC) rules. Summary of the Invention

[0004] Note that in the current network-requested PDU session modification process, there is no mechanism to indicate to the PCF and thus to the application function (AF) a failure regarding a temporary situation that is not related to lack of resources and can be resolved when the UE becomes reachable.

[0005] Embodiments herein propose methods, network functions, computer-readable media, and computer program products for smart policy rule updates.

[0006] In some embodiments, a method performed by a second network function implementing a session management function (SMF) is proposed. The method may include the following steps: receiving a first message from a first network function implementing an access and mobility management function (AMF), the first message including a first parameter indicating a first retry-after time. The first retry-after time may indicate that the second network function stops sending messages to the UE before the first retry-after time expires. The method may further include the following steps: based on the first message, sending a second message to a third network function implementing a PCF, the second message including a second parameter indicating a second retry-after time, during which the UE is considered unreachable.

[0007] In one embodiment, the second retry time after can be set based on the first retry time after.

[0008] In one embodiment, the first and second messages may each further include a fourth parameter indicating the cause of failure. In one embodiment, the cause of failure may be that the UE is temporarily unavailable.

[0009] In one embodiment, the method may further include the step of: after the retry timer after expires, receiving a fifth message for retrying a policy update for failure or sending a change to the cache from a third network function.

[0010] In one embodiment, the first message may be an N1N2 message transmission response message or an N1N2 message transmission failure notification message. In one embodiment, the second message may be a session management policy control update request message. In one embodiment, the fifth message may be a session management policy control update notification request message.

[0011] In some embodiments, a method performed by a third network function implementing a PCF is provided. The method may include the steps of: receiving a second message from a second network function implementing an SMF, the second message including a second parameter indicating a second retry time after, during which the UE is considered unreachable. The method may further include the step of: sending a third message to a fourth network function implementing an AF, the third message including a third parameter indicating a third retry time after. The third retry time after may indicate that the fourth network function suppresses transmitting a message to the third network function when the third retry time after runs.

[0012] In one embodiment, the second and third messages may each further include a fourth parameter indicating the cause of failure. In one embodiment, the cause of failure may be that the UE is temporarily unavailable.

[0013] In one embodiment, the method may further include the step of receiving a subscription regarding a failure event from the fourth network function. In one embodiment, the third message may be sent in response to the failure event.

[0014] In one embodiment, the method may further include the step of: after the third retry time after expires, receiving a fourth message for retrying the configured application or service information from the fourth network function.

[0015] In one embodiment, the method may further include the step of: in response to the fourth message, transmitting a fifth message for retrying a policy update for failure or sending a change to the cache to the second network function.

[0016] In one embodiment, the second message may be a session management policy control update request message. In one embodiment, the third message may be an event report message. In one embodiment, the fourth message may be an application / service information provisioning message. In one embodiment, the fifth message may be a session management policy control update notification request message.

[0017] In one embodiment, the session management policy may be a PCC rule.

[0018] In some embodiments, a method performed by a fourth network function implementing an AF is provided. The method may include the steps of: receiving, from a third network function implementing a PCF, a third message that includes a third parameter indicating a retry time after the third. The retry time after the third may indicate that the fourth network function suppresses transmitting a message to the third network function during the retry time after the third.

[0019] In one embodiment, the method may further include the steps of: starting a retry timer after according to the third parameter to suppress transmitting a message to the third network function while the retry timer is running.

[0020] In one embodiment, the third message may further include a fourth parameter indicating a failure reason. In one embodiment, the failure reason may be that the UE is temporarily unavailable.

[0021] In one embodiment, the method may further include the steps of: transmitting a subscription regarding the failure event to the third network function. In one embodiment, the third message may be transmitted in response to the failure event.

[0022] In one embodiment, the method may further include the steps of: after the retry timer expires, transmitting a fourth message for retrying to provision application or service information to the third network function.

[0023] In one embodiment, the third message may be an event report message. In one embodiment, the fourth message may be a session management policy control update notification request message.

[0024] In one embodiment, the session management policy may be a PCC rule.

[0025] In some embodiments, a network function is provided. In one embodiment, the network function may include at least one processor; and a non-transitory computer-readable medium coupled to the at least one processor. The non-transitory computer-readable medium may store instructions executable by the at least one processor, whereby the at least one processor may be configured to perform any of the above methods. In one embodiment, the network function may be configured as the first network function, the second network function, the third network function, or the fourth network function.

[0026] In some embodiments, a computer-readable medium including computer-readable code is provided, and when the computer-readable code runs on a device, the device can be caused to execute any of the above methods.

[0027] In some embodiments, a computer program product including computer-readable code is provided, and when the computer-readable code runs on a device, the device can be caused to execute any of the above methods.

[0028] When the UE is not reachable or the UE is busy with other processes, the embodiments can reduce the signal exchange between the PCF and the SMF and between the AF and the PCF. In addition, the embodiments can reduce paging from the AMF and can save radio access network (RAN) resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings incorporated herein and constituting a part of the specification illustrate various embodiments of the present disclosure and, together with the specification, further serve to explain the principles of the present disclosure and enable those skilled in the relevant art to make and use the embodiments disclosed herein. In the drawings, like reference numerals indicate the same or functionally similar elements, and in which: Figure 1 is a schematic block diagram showing an example architecture of a 5G network architecture in a non-roaming scenario; Figure 2 is a schematic signaling diagram showing messages during a PDU session modification process of an example network request; Figure 3 is a schematic signaling diagram showing messages during an example process for an improved message suppression sequence flow according to an embodiment herein; Figure 4 is a schematic signaling diagram showing messages during another example process for an improved message suppression sequence flow according to an embodiment herein; Figure 5 is a schematic flowchart showing an example method in a second network function according to an embodiment herein; Figure 6 is a schematic flowchart showing an example method in a third network function according to an embodiment herein; Figure 7 is a schematic flowchart showing an example method in a fourth network function according to an embodiment herein; Figure 8 is a schematic block diagram showing an example second network function according to an embodiment herein; Figure 9 is a schematic block diagram showing an example third network function according to an embodiment herein; Figure 10 is a schematic block diagram showing an example fourth network function according to an embodiment herein; and Figure 11is a schematic block diagram showing an example computer-implemented device according to an embodiment of the present disclosure. Detailed Description of the Invention

[0030] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings, in which embodiments are shown. However, these embodiments of the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments described herein. The elements in the drawings are not necessarily drawn to scale relative to each other.

[0031] Reference to "an embodiment" or "one embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in an embodiment" throughout the specification are not necessarily all referring to the same embodiment.

[0032] As used herein, the term "A, B, or C" means "A" or "B" or "C"; the term "A, B, and C" means "A" and "B" and "C"; and the term "A, B, and / or C" means "A", "B", "C", "A and B", "A and C", "B and C", or "A, B, and C".

[0033] Embodiments may be implemented in an example architecture 100 as shown in Figure 1 below.

[0034] In one embodiment, the example architecture 100 may be configured in an over-the-top (OTT) scenario. The OTT connection may be transparent in the sense that the participating communication devices through which the OTT connection passes are unaware of the routing of the uplink and downlink communications. For example, the base station may not or need not be informed of the past routing of incoming downlink communications, where data originating from network functions in the core network (such as AMF 101, SMF 102, PCF 103, AF 104, or user plane function (UPF) 105) is to be forwarded (e.g., switched) to the connected UE 106. Similarly, the base station need not know the future routing of outgoing uplink communications originating from the UE 106 towards network functions in the core network (such as AMF 101, SMF 102, PCF 103, AF 104, or UPF 105).

[0035] It should also be understood that network functions (such as Figure 1 AMF 101, SMF 102, PCF 103, AF 104, or UPF 105 in may be implemented as network elements on dedicated hardware, software instances running on dedicated hardware, or virtualized functions instantiated on a suitable platform (e.g., on a cloud infrastructure).

[0036] Figure 2 The PDU session modification process for the network request in

[0037] Step 1. The AF 104 may provide application / service information to the PCF 103 by sending a call to the Npcf_PolicyAuthorization service (which may be to create, update, or terminate an AF session). The PCF 103 may reply.

[0038] Step 2. The PCF 103 may make a policy decision. The PCF 103 may determine that it needs to send updated or new policy information to the SMF 102:

[0039] Step 2a. (PCF-initiated session management (SM) policy association modification). The PCF 103 may perform a PCF-initiated SM policy association modification process to notify the SMF 102 about the policy modification.

[0040] Step 2b. The SMF 102 may confirm the PCF request by means of an Npcf_SMPolicyControl_UpdateNotify response.

[0041] Step 3. The SMF 102 may initiate an N4 session establishment or modification process for the new or modified service quality (QoS) flow(s).

[0042] Step 3a. The SMF 102 may update the UPF 105 with N4 rules related to the new or modified QoS flow(s).

[0043] Step 3b. The UPF 105(s) may respond to the SMF 102.

[0044] Step 4. For the modification requested by the SMF, the SMF 102 may call Namf_Communication_N1N2MessageTransfer([N2 SM information] (PDU session ID, QFI(s), QoS profile(s), [alternate QoS profile(s)], session-AMBR, [CN tunnel information(s)], QoS monitoring indication, QoS monitoring reporting frequency, [TSCAI(s)]), N1 SM container (PDU session modification command (PDU session ID, QoS rule(s), QoS flow level QoS parameters (if required for the QoS flow(s) associated with the QoS rule(s)), QoS rule operation and QoS flow level QoS parameter operation, session-AMBR))).

[0045] Step 5. The AMF 101 can detect that the UE is not reachable for paging.

[0046] Step 6. The AMF 101 can respond with the status code "504 Gateway Timeout". The AMF 101 can set the application error to "UE_TEMPORARILY_UNAVAILABLE" in the POST response body, and the AMF 101 can set a retry-after to request the SMF 102 to stop sending N1 / N2 messages before the timeout.

[0047] Step 7. The SMF 102 can start a retry-after timer to prohibit sending N1 / N2 messages before the retry-after timer expires.

[0048] Step 8. The SMF 102 can send an Npcf_SMPolicyControl_Update request to report the implementation failure of one or more PCC rules.

[0049] Step 9. When the AF 104 has subscribed to receive notifications about resource allocation results, the PCF 103 can report the event to the AF 104 by invoking the Npcf_PolicyAuthorization_Notify service operation.

[0050] Step 10. The PCF 103 can answer with an Npcf_SMPolicyControl_Update response.

[0051] Step 11. If the N4 rules are set or modified in Step 2, the SMF 102 can send a UPF 105 session release or modification procedure to roll back the new or modified QoS flow(s).

[0052] Step 12. The AF 104 can retry the application / service information with the PCF 103.

[0053] Step 13. The PCF 103 can execute the SM policy association modification process again. It is possible that the same failure may occur due to the UE being unreachable.

[0054] In one case, when the PCF 103 invokes the Npcf_SMPolicyControl_UpdateNotify service operation to install a new / modified PCC rule, the SMF 102 will send a Namf_N1N2MessageTransfer request to transfer N1 and N2 information via the AMF 101. The SMF 102 may receive an HTTP 409 or 504 status code from the AMF 101 as a response to the Namf_N1N2MessageTransfer request, with a "retry-after timer" information element (IE) (which means that the UE 106 is not reachable at the time of being contacted, and the AMF 101 requests the SMF 102 to retry after the retry-after timer expires).

[0055] In this case, since the PCC rule cannot be successfully installed / modified, the SMF 102 needs to report an error to the PCF 103, and this error should be reported to the AF 104. However, there is no specified error to indicate to the PCF 103 and thus to the AF 104 that the failure is related to a temporary situation, and the PCF 103 (based on the AF request) should not retry installing the PCC rule for this UE during a specific time period indicated by the AMF 101 to the SMF 102 or locally configured in the SMF 102.

[0056] Currently, the Npcf_SMPolicyControl_Update or Npcf_PolicyAuthorization_Notify request message body lacks the awareness to let the PCF 103 or the AF 104 know what the problem is, when the situation will resume, and when appropriate decisions (such as retrying the service or changing the policy information) can be made in the PCF 103 and / or the AF 104.

[0057] In view of the above deficiencies, the embodiments of this article propose to introduce a new "retryAfter" attribute in the "RuleReport" data type to indicate the "retry-after timer" IE received by the SMF 102 from the AMF 101, so that the PCF 103 will not initiate the installation of one or more PCC rules during the time period estimated by the AMF, during which the UE 106 is considered unreachable or there is an ongoing registration process or an ongoing Xn or N2 handover process.

[0058] In addition, a new failure code value "UE_TEMPORARILY_UNAVAILABLE" is defined to notify the PCF 103 that the PCC rule has not been successfully installed / modified due to the UE 106 being unreachable.

[0059] In addition, a new feature "UEUnreachable" is defined to introduce the handling of a new event "UE_TEMPORARILY_UNAVAILABLE" associated with an optional timer (i.e., the retry timer later) in the "AfEventNotification" data type, so as to report the situation to the AF 104 (when the AMF 101 cannot accept resource modification due to the unavailability of the UE 106).

[0060] Figure 3 is a schematic signaling diagram of a message in an example process for improving a message suppression sequence flow shown according to an embodiment herein. Figure 3 An improved message suppression sequence flow due to UE unavailability is described.

[0061] In one embodiment, Figure 3 the process for improving the message suppression sequence flow may include the following messages or steps:

[0062] Step 1. The AF 104 may provide application / service information to the PCF 103 by invoking the Npcf_PolicyAuthorization service.

[0063] Step 2. The PCF 103 may make a policy decision. The PCF 103 may determine that updated or new policy information needs to be sent to the SMF 102:

[0064] Step 2a. (PCF-initiated SM policy association modification). The PCF 103 may execute a PCF-initiated SM policy association modification process to notify the SMF 102 about the policy modification.

[0065] Step 2b. The SMF 102 may confirm the PCF request through an Npcf_SMPolicyControl_UpdateNotify response.

[0066] Step 3. The SMF 102 may initiate an N4 session establishment or modification process for the new or modified QoS flow(s).

[0067] Step 3a. The SMF 102 may update the UPF 105 with N4 rules related to the new or modified QoS flow(s).

[0068] Step 3b. The UPF 105(s) may respond to the SMF 102.

[0069] Step 4. For the modification requested by the SMF, the SMF 102 may invoke Namf_Communication_N1N2MessageTransfer([N2 SM Information] (PDU session ID, (one or more) QFIs, (one or more) QoS profiles, [(one or more) alternative QoS profiles], session-AMBR, [(one or more) CN tunnel information], QoS monitoring indication, QoS monitoring reporting frequency, [(one or more) TSCAIs]), N1 SM container (PDU session modification command (PDU session ID, (one or more) QoS rules, QoS flow level QoS parameters (if required for (one or more) QoS flows associated with (one or more) QoS rules), QoS rule operation and QoS flow level QoS parameter operation, session-AMBR))).

[0070] Step 5. The AMF 101 may detect that the UE is not reachable for paging.

[0071] Step 6. The AMF 101 may respond with the status code "504 Gateway Timeout". The AMF 101 may set the application error to "UE_NOT_REACHABLE" in the POST response body, and the AMF 101 may set a retry later (first retry later timer) to request the SMF 102 to stop sending N1 / N2 messages before the timeout.

[0072] Step 7. If the retry later timer is received, the SMF 102 may start the retry later timer according to the received timer. Otherwise, it may set the retry later timer based on the local configuration to suppress sending N1 / N2 messages before the retry later timer times out.

[0073] Step 8. The SMF 102 may send an Npcf_SMPolicyControl_Update request to report the enforcement failure of (one or more) PCC rules, including the failure code "UE_TEMPORARILY_UNAVAILABLE" and the retry later timer (second retry later timer).

[0074] Step 9. When the AF 104 has subscribed to the relevant event, the PCF 103 may report the event "UE_TEMPORARILY_UNAVAILABLE" to the AF 104 by invoking the Npcf_PolicyAuthorization_Notify service operation, with the retry later timer (third retry later timer). The AF 104 may reply.

[0075] In one example, for step 8 and / or step 9, a new "Retry After" attribute is introduced in the "RuleReport" data type, such that during the time estimated by the AMF (the first retry after time) or the time estimated by the SMF (the second retry after time), the AF 104 does not re-attempt to provide application / service information to the PCF 103, or the PCF 103 does not initiate the installation of one or more PCC rules, during which time the UE 106 is considered unreachable.

[0076] In addition, a new failure code value "UE_TEMPORARILY_UNAVAILABLE" is introduced to inform the PCF 103 and AF 104 of what the problem is.

[0077] In one example, step 8 and / or step 9 may include the RuleReport in Table 1. Table 1: Definition of Type RuleReport

[0078] In one example, step 8 and / or step 9 may also include the failure codes in Table 2. Table 2: Enumerated Failure Codes (FailureCode)

[0079] In one example, the feature negotiation on the Npcf_SMPolicyControl API can be defined as in Table 3. Table 3: Supported Features

[0080] In one example, the event report in step 9 may include the parameters in Table 4. Table 4: Definition of Type AfEventNotification

[0081] In one example, the event report in step 9 may include the parameters in Table 5. Table 5: Enumerated AfEvent

[0082] In one example, the feature negotiation of the event report in step 9 may include the features in Table 6. Table 6: Supported Features

[0083] Step 10. PCF 103 may answer through the Npcf_SMPolicyControl_Update response.

[0084] Step 11. If the N4 rule is set or modified in step 3, SMF 103 may send a UPF session release or modification procedure to roll back the new or modified QoS flow(s).

[0085] Step 12. An NF (such as AF) 104 may start a retry timer later.

[0086] Step 13. AF 104 may re-attempt to provision the application / service information to PCF 103 after the timer expires.

[0087] Step 14. When the timer has expired, PCF 103 may send an SM policy association modification procedure regarding the installation, reinstallation, modification, or removal of PCC rules to SMF 102. PCF 103 may still install PCC rules that do not generate any N1 actions (e.g., predefined PCC rules in the default QoS flow) before the expiration.

[0088] Step 14a. PCF 103 may execute a PCF-initiated SM policy association modification procedure to notify SMF 102 about the policy modification.

[0089] Step 14b. SMF 102 may confirm the notification.

[0090] Figure 4 It is a schematic signaling diagram of messages in another example process showing an improved message suppression sequence flow according to embodiments herein. Figure 4 Describes an improved message suppression sequence flow due to a temporary rejection of an ongoing process.

[0091] In one embodiment, Figure 4 the process of the improved message suppression sequence flow may include the following messages or steps:

[0092] Step 1. AF 104 may provide the application / service information to PCF 103 by invoking the Npcf_PolicyAuthorization service.

[0093] Step 2. The PCF 103 can make a policy decision. The PCF 103 can determine that updated or new policy information needs to be sent to the SMF 102:

[0094] Step 2a. (PCF-initiated SM Policy Association Modification). The PCF 103 can execute a PCF-initiated SM Policy Association Modification procedure to notify the SMF 102 about the policy modification.

[0095] Step 2b. The SMF 102 can confirm the PCF request through an Npcf_SMPolicyControl_UpdateNotify response.

[0096] Step 3. The SMF 102 can initiate an N4 session establishment or modification procedure for the new or modified QoS flow(s).

[0097] Step 3a. The SMF 102 can update the UPF 105 with N4 rules related to the new or modified QoS flow(s).

[0098] Step 3b. The UPF 105(s) can respond to the SMF 102.

[0099] Step 4. If the UE 106 is in the CM-IDLE state at the AMF 101 and the AMF 101 is able to page the UE 106, the AMF 101 can immediately send a Namf_Communication_N1N2MessageTransfer response to the SMF 102 to indicate to the SMF 102 that the AMF 101 is attempting to contact the UE 106.

[0100] Step 5. For the modification requested by the SMF, the SMF 102 can invoke Namf_Communication_N1N2MessageTransfer([N2 SM information] (PDU session ID, QFI(s), QoS profile(s), [alternate QoS profile(s)], session-AMBR, [CN tunnel information(s)], QoS monitoring indication, QoS monitoring reporting frequency, [TSCAI(s)]), N1 SM container (PDU session modification command (PDU session ID, QoS rule(s), QoS flow level QoS parameters (if required for the QoS flow(s) associated with the QoS rule(s)), QoS rule operation and QoS flow level QoS parameter operation, session-AMBR))).

[0101] Step 6. The AMF 101 may send a paging message to the (one or more) NG-RAN nodes via 3GPP access.

[0102] Step 7. The NG-RAN may send a paging message to the UE 106.

[0103] Step 8. If the AMF 101 has initiated paging to reach the UE 106 but there is an ongoing registration process, the AMF 101 may notify the SMF 102 by sending a Namf_Communications_N1N2MessageTransfer failure notification to the notification target address provided by the SMF 102 in Step 2. The body message may include the failure reason and a subsequent retry timer (the first subsequent retry time) to request the NF service consumer to stop sending N1 / N2 messages before the timeout. Another possible procedure is that the AMF 101 may respond with a Namf_Communications_N1N2MessageTransfer with a 409 status code, including the reason ("TEMPORARY_REJECT_REGISTRATION_ONGOING" or "TEMPORARY_REJECT_HANDOVER_ONGOING") and the subsequent retry in Step 5.

[0104] Step 9. If a subsequent retry timer is received, the SMF 102 may start the subsequent retry timer according to the received timer. Otherwise, the SMF 102 may set the subsequent retry timer (the second subsequent retry time) based on local configuration to suppress sending N1 / N2 messages before the subsequent retry timer times out.

[0105] Step 10. The SMF 102 may send a Npcf_SMPolicyControl_Update request to report the enforcement failure of the (one or more) PCC rules, including the failure code "UE_TEMPORARILY_UNAVAILABLE" and / or the subsequent retry timer.

[0106] Step 11. When the AF 104 has subscribed to an event that is satisfied due to the report from the SMF 102, the PCF 103 may report the event "UE_TEMPORARILY_UNAVAILABLE" with the subsequent retry timer (the third subsequent retry time) to the AF 104 by invoking the Npcf_PolicyAuthorization_Notify service operation.

[0107] In one example, for step 10 and / or step 11, a new "retryAfter" attribute is introduced in the "RuleReport" data type so that during the time estimated by the AMF (the first retry-after time) or the time estimated by the SMF (the second retry-after time), AF 104 will not re-attempt to provide application / service information to PCF 103, or PCF 103 will not initiate the installation of one or more PCC rules, during which time UE 106 is busy with one or more other processes.

[0108] In addition, when SMF102 receives an N1N2 transmission failure with the reason of "TEMPORARY_REJECT_REGISTRATION_ONGOING" or "TEMPORARY_REJECT_HANDOVER_ONGOING", a new "FailureCode" value, namely "UE_TEMPORARILY_UNAVAILABLE", is introduced to notify PCF 103 and AF 104 of what the problem is.

[0109] In one example, step 10 and / or 11 may also include the parameters shown in Tables 1 to 6 above.

[0110] Step 12. PCF 103 may answer with an Npcf_SMPolicyControl_Update response.

[0111] Step 13. If the N4 rule is set or modified in step 3, SMF 102 may send a UPF session release or modification procedure to roll back one or more new or modified QoS flows.

[0112] Step 14. An NF (such as AF 104) may start a retry-after timer.

[0113] Step 15. AF 104 may retry equipping PCF 103 with application / service information after the timer expires.

[0114] Step 16. When the timer has expired, PCF 103 may send an SM policy association modification procedure regarding the installation, reinstallation, modification, or removal of PCC rules to SMF 102. PCF 103 may still install PCC rules that do not generate any N1 actions before the expiration (e.g., predefined PCC rules in the default QoS flow).

[0115] Step 16a. PCF 103 may execute a PCF-initiated SM policy association modification procedure to notify SMF of the policy modification.

[0116] Step 16b. SMF 102 may confirm the notification.

[0117] The embodiments may allow the PCF 103 and the AF 104 to know what the problem is and when it can retry the service or retry changing the policy information.

[0118] The embodiments may prevent the AF 104 and the PCF 103 from retrying the request until the timer associated with the paging procedure has expired.

[0119] When the UE 106 is not reachable or the UE 106 is busy with other process(es), the embodiments may reduce the signal exchange between the PCF 103 and the SMF 102.

[0120] The embodiments may reduce the paging from the AMF 101 and may save RAN resources.

[0121] Figure 5 is a schematic flowchart showing an example method 500 in a second network function (such as the SMF 102) according to embodiments herein.

[0122] Method 500 may start at step S501, where the second network function (such as the SMF 102) may receive a first message from the first network function (such as the AMF 101), the first message including a first parameter indicating a first retry time after.

[0123] In one embodiment, the first retry time after may indicate that the second network function stops sending messages to the UE (such as the UE 106) before the first retry time after times out. In one embodiment, the first message may further include a fourth parameter indicating a failure reason. In one embodiment, the failure reason may be that the UE is temporarily unavailable.

[0124] In one embodiment, the first message may be an N1N2 message transmission response message or an N1N2 message transmission failure notification message.

[0125] Then, method 500 may proceed to step S502, where the second network function (such as the SMF 102) may, based on the first message, transmit a second message to a third network function (such as the PCF 103), the second message including a second parameter indicating a second retry time after, during which the UE is considered unreachable.

[0126] In one embodiment, the second retry time after may be set based on the first retry time after.

[0127] In one embodiment, the second message may further include a fourth parameter indicating a failure reason. In one embodiment, the failure reason may be that the UE is temporarily unavailable.

[0128] In one embodiment, the second message may be a session management policy control update request message.

[0129] In one embodiment, the second network function (such as SMF 102) may further include the step of starting a post-retry timer to inhibit the transmission of N1 and / or N2 messages.

[0130] Then, method 500 may proceed to step S503, where, after the post-retry timer expires, the second network function (such as SMF 102) may receive a fifth message from the third network function for retrying the failed policy update or sending cached changes.

[0131] In one embodiment, the fifth message may be a session management policy control update notification request message.

[0132] The above steps are merely examples, and the second network function (such as SMF 102) may perform any operation regarding Figures 2 - 4 described to inform the PCF 103 of what the problem is and when the service can be retried or the policy information can be retried for change.

[0133] Figure 6 is a schematic flowchart showing an example method 600 in a third network function (such as PCF 103) according to an embodiment herein.

[0134] Method 600 may begin at step S601, where the third network function (such as PCF 103) may receive a second message from the second network function (such as SMF 102), the second message including a second parameter indicating a second post-retry time during which the UE (such as UE 106) is considered unreachable.

[0135] In one embodiment, the second message may further include a fourth parameter indicating a failure reason. In one embodiment, the failure reason may be that the UE is temporarily unavailable.

[0136] In one embodiment, the second message may be a session management policy control update request message.

[0137] In one embodiment, the third network function (such as PCF 103) may further include the step of starting a post-retry timer to inhibit message transmission to SMF 102 (not shown).

[0138] Then, method 600 may proceed to step S602, where the third network function (such as PCF 103) may receive a subscription regarding the failure event from the fourth network function (such as AF 104).

[0139] Then, method 600 may continue to step S603, where a third network function (such as PCF 103) may transmit a third message to a fourth network function (such as AF 104), and the third message includes a third parameter indicating a retry time after the third time. The retry time after the third time may indicate that the fourth network function suppresses transmitting a message to the third network function when the retry time after the third time runs.

[0140] In one embodiment, the third message may be transmitted in response to a failure event.

[0141] In one embodiment, the third message may further include a fourth parameter indicating a cause of failure. In one embodiment, the cause of failure may be that the UE is temporarily unavailable.

[0142] In one embodiment, the third message may be an event report message.

[0143] Then, method 600 may continue to step S604, where the third network function (such as PCF 103) may receive, after the retry time expires, a fourth message from the fourth network function for retrying to configure application or service information.

[0144] In one embodiment, the fourth message may be an application / service information configuration message.

[0145] Then, method 600 may continue to step S605, where the third network function (such as PCF 103) may, in response to the fourth message, transmit a fifth message to a second network function (such as SMF 102) for retrying a failed policy update or sending a cache change.

[0146] In one embodiment, the fifth message may be a session management policy control update notification request message. In one embodiment, the session management policy may be a PCC rule.

[0147] The above steps are only examples, and the third network function (such as PCF 103) may perform any operation regarding Figures 2 - 4 described to enable AF 104 to understand what the problem is and when it can retry the service or retry changing the policy information.

[0148] Figure 7 is a schematic flowchart showing an example method 700 in a fourth network function (such as AF 104) according to an embodiment herein.

[0149] Method 700 may start at step S701, where the fourth network function (such as AF 104) may transmit a subscription regarding a failure event to the third network function (such as PCF 103).

[0150] Then, method 700 may proceed to step S702, where a fourth network function (such as AF 104) may receive a third message from a third network function, the third message including a third parameter indicating a third retry time after. The third retry time after may indicate that the fourth network function suppresses transmitting messages to the third network function during the third retry time after.

[0151] In one embodiment, the third message may further include a fourth parameter indicating a cause of failure. In one embodiment, the cause of failure may be that the UE is temporarily unavailable.

[0152] In one embodiment, the third message may be transmitted in response to a failure event.

[0153] In one embodiment, the third message may be an event report message.

[0154] Then, method 700 may proceed to step S703, where the fourth network function (such as AF 104) may start a retry timer after according to the third parameter to suppress transmitting messages to the third network function while the retry timer after is running.

[0155] Then, method 700 may proceed to step S704, where the fourth network function (such as AF 104) may transmit a fourth message for retrying to configure application or service information to the third network function after the retry timer after expires.

[0156] In one embodiment, the fifth message may be a session management policy control update notification request message.

[0157] In one embodiment, the session management policy may be a PCC rule.

[0158] The above steps are only examples, and the fourth network function (such as AF 104) may perform any action regarding Figures 2 - 4 described to enable AF 104 to understand what the problem is and when it can retry the service or retry changing the policy information.

[0159] Figure 8 is a schematic block diagram showing an example second network function 800 (such as SMF 102) according to an embodiment herein.

[0160] In one embodiment, the second network function 800 may include at least one processor 801; and a non-transitory computer-readable medium 802 coupled to the at least one processor 801. The non-transitory computer-readable medium 802 may store instructions executable by the at least one processor 801, whereby the at least one processor 801 may be configured to perform the steps in the example method 500 shown in the schematic flowchart as Figure 5 shown; the details are omitted herein.

[0161] Note that the second network function 800 can be implemented as hardware, software, firmware, and any combination thereof. For example, the second network function 800 may include a plurality of units, circuits, modules, or the like, each of which can be used to perform one or more steps of the example method 500, or one or more steps related to the SMF 102.

[0162] It should be understood that the second network function 800 can be implemented as a network element on dedicated hardware, a software instance running on dedicated hardware, or a virtualized function instantiated on a suitable platform (e.g., on a cloud infrastructure).

[0163] Figure 9 is a schematic block diagram showing an example third network function 900 (such as the PCF 103) according to an embodiment herein.

[0164] In one embodiment, the third network function 900 may include at least one processor 901; and a non-transitory computer-readable medium 902 coupled to the at least one processor 901. The non-transitory computer-readable medium 902 may store instructions executable by the at least one processor 901, whereby the at least one processor 901 may be configured to execute the steps in the example method 600 as shown in Figure 6 the schematic flowchart shown; the details of which are omitted herein.

[0165] Note that the third network function 900 can be implemented as hardware, software, firmware, and any combination thereof. For example, the third network function 900 may include a plurality of units, circuits, modules, or the like, each of which can be used to perform one or more steps of the example method 600, or one or more steps related to the PCF 103.

[0166] It should be understood that the third network function 900 can be implemented as a network element on dedicated hardware, a software instance running on dedicated hardware, or a virtualized function instantiated on a suitable platform (e.g., on a cloud infrastructure).

[0167] Figure 10 is a schematic block diagram showing an example fourth network function 1000 (such as the AF 104) according to an embodiment herein.

[0168] In one embodiment, the fourth network function 1000 may include at least one processor 1001; and a non-transitory computer-readable medium 1002 coupled to the at least one processor 1001. The non-transitory computer-readable medium 1002 may store instructions executable by the at least one processor 1001, whereby the at least one processor 1001 may be configured to execute the steps in the example method as shown in Figure 7The steps in the example method 700 shown in the schematic flowchart; details thereof are omitted herein.

[0169] Note that the fourth network function 1000 can be implemented as hardware, software, firmware, and any combination thereof. For example, the fourth network function 1000 can include multiple units, circuits, modules, or the like, each of which can be used to execute one or more steps of the example method 700, or one or more steps related to the AF 104.

[0170] It should be understood that the fourth network function 1000 can be implemented as a network element on dedicated hardware, a software instance running on dedicated hardware, or a virtualized function instantiated on a suitable platform (e.g., on a cloud infrastructure).

[0171] Figure 11 is a schematic block diagram of an example computer-implemented device 1100 according to an embodiment herein. In one embodiment, the device 1100 can be configured as the above-mentioned devices, such as the SMF 102, PCF 103, AF 104, second network function 800, third network function 900, or fourth network function 1000.

[0172] In one embodiment, the device 1100 can include, but is not limited to, at least one processor, such as a central processing unit (CPU) 1101, a computer-readable medium 1102, and a memory 1103. The memory 1103 can include volatile memory (e.g., random access memory, RAM) and / or non-volatile memory (e.g., a hard disk or flash memory). In one embodiment, the computer-readable medium 1102 can be configured to store a computer program and / or instructions, which, when executed by the processor 1101, cause the processor 1101 to execute any of the above methods.

[0173] In one embodiment, the computer-readable medium 1102 (such as a non-transitory computer-readable medium) can be stored in the memory 1103. In another embodiment, the computer program can be stored in a remote location, such as a computer program product 1104 (which can also be implemented as a computer-readable medium), and can be accessed by the processor 1101 via, for example, a carrier 1105.

[0174] The computer-readable medium 1102 and / or the computer program product 1104 may be distributed and / or stored on a removable computer-readable medium, such as a floppy disk, a CD (compact disc), a DVD (digital video disc), a flash memory, or a similar removable storage medium (such as a compact flash, an SD (secure digital), a memory stick, a mini SD card, an MMC (multimedia card), a smart media), an HD-DVD (high definition DVD) or a Blu-ray DVD, a USB (universal serial bus)-based removable storage medium, a magnetic tape medium, an optical storage medium, a magneto-optical medium, a magnetic bubble memory, or may be distributed as a propagated signal via a network (such as Ethernet, ATM, ISDN, PSTN, X.25, the Internet, a local area network (LAN), or a similar network capable of transmitting data packets to an infrastructure node).

[0175] In addition, the following modifications are proposed to modify the current 3GPP technical specification 3GPP TS 29.512 (the underlined parts indicate the changes).

[0176] 5.6.2.27 Type RuleReport Table 5.6.2.27-1: Definition of Type RuleReport

[0177] 5.6.3.9 Enumeration: FailureCode Table 5.6.3.9-1: Enumeration FailureCode

[0178] 5.8 Feature Negotiation The optional features in Table 5.8-1 are defined for the Npcf_SMPolicyControl API. They shall be negotiated using the extension mechanism defined in clause 6.6 of 3GPP TS 29.500 [4]. Table 5.8-1: Supported Features

[0179] In addition, the following modifications are proposed to modify the current 3GPP technical specification 3GPP TS 29.514 (the underlined parts indicate the changes). 4.2.2.10 Reservation Resource Allocation Result

[0180] When the resources associated with the corresponding service information have been allocated and / or cannot be allocated, the NF service consumer uses this procedure to reserve notifications.

[0181] The NF service consumer shall use the "EventsSubscReqData" data type as described in clause 4.2.2.2 and shall include in the HTTP POST request message: - An event entry within the "events" attribute, where the "event" attribute is set to "SUCCESSFUL_RESOURCES_ALLOCATION" (if the NF service consumer requests the PCF to provide a notification when the resources associated with the service information have been allocated); - An event entry within the "events" attribute, where the "event" attribute is set to "FAILED_RESOURCES_ALLOCATION" (if the NF service consumer requests the PCF to provide a notification when the resources associated with the service information cannot be allocated); and / or - An event entry within the "events" attribute, where the "event" attribute is set to " UE_TEMPORARILY_ UNAVAILABLE "(if the "UEUnreachable" feature is supported and the NF service consumer requests the PCF to provide a notification when the resources associated with the service information are not allocated due to the UE being unreachable).

[0182] The PCF shall reply to the NF service consumer as described in clause 4.2.2.2.

[0183] As a result of this action, the PCF shall set the appropriate reservation for the resource allocation result notification for the corresponding PCC rule(s), as described in 3GPP TS 29.512 [8]. 4.2.3.10 Modifying the reservation for the resource allocation result

[0184] This procedure is used by the NF service consumer to modify the reservation for the notification related to the resource allocation result in the PCF.

[0185] The NF service consumer shall use the HTTP PATCH method to update the "event reservation" sub-resource together with the modification to the "single application session context" resource.

[0186] The NF service consumer shall include in the "ascReqData" attribute in the HTTP PATCH request message described in clause 4.2.3.2 an updated value of the "EventsSubscReqDataRm" data type, where the updated value either includes in the "events" attribute a new element with the "event" attribute set to "SUCCESSFUL_RESOURCES_ALLOCATION", "FAILED_RESOURCES_ALLOCATION" and / or "UE_TEMPORARILY_UNAVAILABLE", or removes an existing element in the "events" attribute with the "event" attribute set to "SUCCESSFUL_RESOURCES_ALLOCATION", "FAILED_RESOURCES_ALLOCATION" and / or "UE_TEMPORARILY_UNAVAILABLE".

[0187] As a result of this action, the PCF shall set appropriate subscriptions for resource allocation result notifications in the corresponding PCC rule(s), as described in 3GPP TS29.512 [8]. 4.2.5.5 Notification on service data flow deactivation

[0188] When the PCF learns that one or more SDFs have been deactivated, the PCF shall notify the NF service consumer accordingly if the NF service consumer has subscribed as described in clauses 4.2.2.7 and 4.2.3.7.

[0189] When not all service data flows in the AF application session context are affected, the PCF shall notify the NF service consumer by including the "EventsNotification" data type in the HTTP POST request body, as described in clause 4.2.5.2.

[0190] The PCF shall include in the "evNotifs" attribute an event of the "AfEventNotification" data type indicating the matching event in the "event" attribute (i.e., "FAILED_RESOURCES_ALLOCATION" if resources cannot be allocated; If "UE_TEMPORARILY_UNAVAILABLE" if the UE is not reachable ), and the deactivated service data flows encoded in the "flows" attribute (if not all flows are affected). Note 1: If the PCF detects that it is not possible to install or modify the PCC rules related to the AF application session context due to a temporary network failure (e.g., the SGW fails according to subclauses B.3.3.3 or B.3.4.9 of 3GPP TS 29.512 [8]), and if the AF requests it, the PCF may notify the AF of the event "FAILED_RESOURCES_ALLOCATION".

[0191] If the "MediaComponentVersioning" feature is supported and if a content version is included when the corresponding media component is equipped (as described in subclause 4.2.5.8), the PCF shall also include the "contVers" attribute in the "flows" attribute, which carries the content version(s) of the media component.

[0192] If the "RAN-NAS-Cause" feature is supported and the PCF receives the RAN-NAS release cause and access network information from the SMF, the PCF shall provide in the "EventsNotification" data type of the HTTP POST request: - In the case of 3GPP access: the user location information in the "eutraLocation" attribute or in the "nrLocation" attribute of the "ueLoc" attribute (if available); - In the case of non-trusted non-3GPP access: the user location information in the "n3gaLocation" attribute of the "ueLoc" attribute (if available), as follows: a) The user local IP address in the "ueIpv4Addr" or "ueIpv6Addr" attribute; b) The UDP source port or TCP source port in the "portNumber" and "protocol" attributes (if available); and c) If the "WLAN_Location" function is supported, the WLAN location information encoded in the "twapId" attribute (if available), which shall include: i. The SSID in the "ssId" attribute; ii. The BSSID of the "bssId" attribute (if available); and iii. The civic address in the "civicAddress" attribute (if available); Note 2: When the UE reaches the ePDG via NAT, the UE local IP address and the UE source port need to be combined for lawful interception purposes. The UE source port can be a UDP port or a TCP port, and it is specified in the "protocol" attribute. - In the case of trusted non-3GPP access: The user location information (if available) in the "n3gaLocation" attribute in the "ueLoc" attribute is as follows: a) The user local IP address in the "ueIpv4Addr" or "ueIpv6Addr" attribute (if available); and b) The UDP source port in the "portNumber" attribute (if available); and Note 3: The UDP protocol can be used between the UE and the TNGF to enable NAT traversal. c) The TNAP identifier encoded in the "tnapId" attribute or the TWAP identifier encoded in the "twapId" attribute. The TNAP identifier and the TWAP identifier shall include: i. The SSID in the "ssId" attribute; ii. The BSSID of the "bssId" attribute (if available); and iii. The civic address in the "civicAddress" attribute (if available); - The serving network identification in the "plmnId" attribute, i.e., the PLMN identifier (PLMN network code and country code) or the SNPN identifier (PLMN identifier and NID) (if the user location information is not available in any access); - The UE time zone in the "ueTimeZone" attribute (if available); and - The RAN and / or NAS release cause in the "ranNasRelCauses" attribute (if available). Note 4: When the following two UE locations are both provided by the SMF, the PCF forwards the 3GPP and non-3GPP access UE locations in the "ueLoc" attribute, as defined in 3GPP TS29.512 [8].

[0193] The PCF shall include an event of the "AfEventNotification" data type in the "evNotifs" attribute together with the event "FAILED_RESOURCES_ALLOCATION", where the "event" attribute is set to the value "RAN_NAS_CAUSE".

[0194] If the PCF has received multiple content versions as described in clause 4.2.6.2.14 of 3GPP TS 29.512 [8], the PCF shall include more than one entry in the "contVers" attribute for the same media component.

[0195] When the NF service consumer receives an HTTP POST request, it shall send a "204 No Content" response to the PCF to confirm the request. The NF service consumer may also update the AF application session context information by sending an HTTP PATCH request to the PCF.

[0196] When all service data flows within an AF session are affected, the PCF shall notify the NF service consumer by sending a notification about the termination of the application session context, as defined in clause 4.2.5.3.

[0197] The signalling flows for service data flow deactivation are given in 3GPP TS 29.513 [7]. 4.2.5.8 Notification of resource allocation result

[0198] When the PCF becomes aware that resources related to the service information of one or more SDFs have been allocated, if the NF service consumer has previously subscribed to the "SUCCESSFUL_RESOURCES_ALLOCATION" event (as described in clauses 4.2.2.10 and 4.2.3.10), the PCF shall notify the NF service consumer accordingly. The PCF shall notify the NF service consumer by including the "EventsNotification" data type in the body of the HTTP POST request (as described in clause 4.2.5.2). The PCF shall include an entry in the "evNotifs" attribute, where the "event" attribute is set to "SUCCESSFUL_RESOURCES_ALLOCATION", and (if not all flows are affected) the identity of the relevant media component in the "flows" attribute. If the "MediaComponentVersioning" feature is supported, the PCF shall also include the "contVers" attribute with the (one or more) content versions of the media component in the "flows" attribute (if content versions were included when the corresponding media component was provisioned).

[0199] If the "AuthorizationWithRequiredQoS" feature or the "AltSerReqsWithIndQoS" feature as defined in clause 5.8 is supported, when the PCF realizes that resources associated with the service information of one or more SDFs have been allocated and additionally receives (one or more) sets of alternative QoS parameters, the PCF shall notify the NF service consumer by including the "EventsNotification" data type in the body of the HTTP POST request, as described in clause 4.2.5.2. The PCF shall include: - An entry in the "evNotifs" attribute, where the "event" attribute is set to "SUCCESSFUL_RESOURCES_ALLOCATION"; and - The "succResourcAllocReports" attribute, with references to the alternative service requirements for the corresponding set of alternative QoS parameters within the "altSerReq" attribute and the identifiers of the relevant media components in the "flows" attribute. If the "MediaComponentVersioning" feature is supported, the PCF shall also include the "contVers" attribute in the "flows" attribute, with the (one or more) content versions of the media component (if content versions were included when the corresponding media component was provisioned).

[0200] When the PCF realizes that resources associated with the service information of one or more SDFs cannot be allocated, if the NF service consumer has previously subscribed to the "FAILED_RESOURCES_ALLOCATION" event (as described in clauses 4.2.2.10 and 4.2.3.10), the PCF shall notify the NF service consumer accordingly. The PCF shall notify the NF service consumer by including the "EventsNotification" data type in the body of the HTTP POST request, as described in clause 4.2.5.2. The PCF shall include: - An entry in the "evNotifs" attribute, where the "event" attribute is set to "FAILED_RESOURCES_ALLOCATION"; and - The "failedResourcAllocReports" attribute, carrying the activation / deactivation status of PCC rules related to certain media components encoded in the "mcResourcStatus" attribute, and (if not all flows are affected) the identification of the related media components in the "flows" attribute. If the "MediaComponentVersioning" feature is supported, the PCF shall also include in the "flows" attribute the "contVers" attribute, carrying the content version(s) of the media component (if a content version was included when equipping the corresponding media component).

[0201] When the "UEUnreachable" feature is supported, and if the PCF realizes that the UE is not reachable and thus does not allocate resources associated with the service information of one or more SDFs, then if the NF service consumer has previously subscribed to the "UE_ TEMPORARILY_UNAVAILABLE" event (as described in clauses 4.2.2.10 and 4.2.3.10), the PCF shall notify the NF service consumer accordingly. The PCF shall notify the NF service consumer by including the "EventsNotification" data class type in the body of an HTTP POST request, as described in clause 4.2.5.2. The PCF shall include: - An entry in the "evNotifs" attribute, where the "event" attribute is set to "UE_TEMPORARILY_ UNAVAILABLE"; - The "failedResourcAllocReports" attribute, with the activation / deactivation status of some media component - related PCC rules encoded in the "mcResourcStatus" attribute, and (if not all flows are affected) the identification of the relevant media components in the "flows" attribute. If the "MediaComponentVersioning" feature is supported, the PCF shall also include the "contVers" attribute in the "flows" attribute, with the (one or more) content versions of the media component (if a content version is included when equipping the corresponding media component); and - The "retryAfter" attribute (if this information is received from the SMF). Figure One Figure One Abbreviations

[0202] If the PCF has received multiple content versions, the PCF shall include more than one entry in the "contVers" attribute for the same media component, as described in clause 4.2.6.2.14 of 3GPP TS 29.512 [8]. Note: When multiple equippings of the same media component occur during a short period, the NF service consumer will use the content version to identify the failed or successful media component version. How the NF service consumer disposes of such cases is outside the scope of this specification.

[0203] When the NF service consumer receives an HTTP POST request, it shall confirm the request by sending a "204 No Content" response to the PCF.

[0204] The signalling flows for resource allocation results are given in 3GPP TS 29.513 [7].

[0205] 5.6.2.11 Type AfEventNotification Table 5.6.2.11-1: Definition of Type AfEventNotification

[0206] 5.6.3.7 Enumeration: AfEvent The enumerated type "AfEvent" represents the service events that the PCF can notify the NF service consumer about. Table 5.6.3.7-1: Enumerated type AfEvent

[0207] The optional features in Table 5.8-1 are defined for the Npcf_PolicyAuthorization API. They shall be negotiated using the extension mechanism defined in clause 6.6.2 of 3GPP TS 29.500 [5].

[0208] When the NF service consumer requests the PCF to create a single application session context resource, the NF service consumer shall indicate the optional features supported by the NF service consumer for the Npcf_PolicyAuthorization service by including the "suppFeat" attribute in the "AppSessionContextReqData" data type of the HTTP POST request.

[0209] The PCF shall determine the supported features for the created single application session context resource (as specified in clause 6.6.2 of 3GPP TS 29.500 [5]). The PCF shall indicate the supported features in the HTTP response acknowledging the creation of the single application session context resource by including the "suppFeat" attribute in the "AppSessionContextRespData" data type.

[0210] 5.8 Feature negotiation Table 5.8-1: Supported features

[0211] Example embodiments are described herein with reference to block diagrams and / or flowcharts of computer-implemented methods, apparatus (systems and / or devices), and / or non-transitory computer program products. It is to be understood that the blocks in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented by computer program instructions executed by one or more computer circuits. These computer program instructions can be provided to the processor circuits of general-purpose computer circuits, special-purpose computer circuits, and / or other programmable data processing circuits to produce a machine, such that the instructions executed via the processor of the computer and / or other programmable data processing devices transform and control transistors, values stored in memory locations, and other hardware components in such circuits to implement the block diagrams and / or flow Figure Onethe functions / actions specified in one or more boxes, and thereby create components (functionalities) and / or structures for implementing the functions / actions specified in the block diagram and / or one or more flowchart boxes.

[0212] These computer program instructions can also be stored in a tangible computer-readable medium, which can direct a computer or other programmable data processing device to operate in a specific manner, such that the instructions stored in the computer-readable medium produce a manufactured article containing the instructions, the instructions implementing the functions / actions specified in the block diagram and / or the flowchart Figure One one or more boxes. Thus, embodiments of the inventive concept can be implemented in hardware and / or software (including firmware, resident software, microcode, etc.) running on a processor (such as a digital signal processor), which can be collectively referred to as "circuitry", "module" or its variants.

[0213] It should also be noted that in some alternative implementations, the functions / actions shown in the boxes may be performed in a different order than that shown in the flowchart. For example, two consecutively shown boxes may actually be performed substantially simultaneously, or the boxes may sometimes be performed in the reverse order, depending on the functionality / action involved. Additionally, the functionality of a given box in the flowchart and / or block diagram can be split into multiple boxes, and / or the functionality of two or more boxes in the flowchart and / or block diagram can be at least partially integrated. Finally, other boxes can be added / inserted between the shown boxes, and / or boxes / operations can be omitted, without departing from the scope of the inventive concept. Further, although some figures include arrows on communication paths to indicate the main communication direction, it is to be understood that communication can occur in the direction opposite to that of the drawn arrows.

[0214] Without materially departing from the principles of the inventive concept, various changes and modifications can be made to the embodiments. All such changes and modifications are intended to be included within the scope of the inventive concept. Thus, the subject matter disclosed above is to be considered illustrative and not restrictive, and the examples of the appended embodiments are intended to cover all such modifications, enhancements, and other embodiments that fall within the spirit and scope of the inventive concept. Accordingly, to the maximum extent permitted by law, the scope of the inventive concept is to be determined by the broadest permissible interpretation of this disclosure (including the examples of the following embodiments and their equivalents), and should not be limited or restricted by the foregoing detailed description.

[0215] Abbreviations 3GPP Third Generation Partnership Project 5G Fifth Generation Mobile Communication Technology AF Application Function AMF Access and Mobility Management Function DDN Downlink Data Notification HTTP HyperText Transfer Protocol LMF Location Management Function NF Network Function OTT Over The Top PCC Policy and Charging Control PCF Policy Control Function PDU Packet Data Unit RAN Radio Access Network SMF Session Management Function SMSF Short Message Service Function UDM Unified Data Management UE User Equipment UPF User Plane Function URI Uniform Resource Identifier.

Claims

1. A method (500) performed by a second network function (102) implementing a session management function (SMF), comprising: - receiving (S501) a first message from a first network function (101) implementing an access and mobility management function (AMF), the first message including a first parameter indicating a first retry time after which the second network function (102) stops sending messages to a user equipment (UE) (106) before the timeout of the first retry time after which; and - based on the first message, transmitting (S502) a second message to a third network function (103) implementing a policy control function (PCF), the second message including a second parameter indicating a second retry time after which the UE (106) is considered unreachable.

2. The method (500) according to claim 1, wherein, the second retry time after which is set based on the first retry time after which.

3. The method (500) according to claim 1 or 2, wherein, each of the first message and the second message further includes a fourth parameter indicating a cause of failure; and wherein the cause of failure is that the UE (106) is temporarily unavailable.

4. The method (500) according to claim 3, further comprising: - after the expiration of the second retry timer after which, receiving (S503) from the third network function (103) a fifth message for retrying a failed policy update or sending a cache change.

5. The method (500) according to any one of claims 1-4, wherein, the first message is an N1N2 message transmission response message or an N1N2 message transmission failure notification message; the second message is a session management policy control update request message; or the fifth message is a session management policy control update notification request message.

6. A method (600) performed by a third network function (103) implementing a policy control function (PCF), comprising: - receiving (S601) a second message from a second network function (102) implementing a session management function (SMF), the second message including a second parameter indicating a second retry time after which a user equipment (UE) (106) is considered unreachable; and - transmitting (S603) a third message to a fourth network function (104) implementing an application function (AF), the third message including a third parameter indicating a third retry time after which the fourth network function (104) inhibits transmitting messages to the third network function (103) when the third retry time after which is running.

7. The method (600) according to claim 6, wherein, each of the second message and the third message further includes a fourth parameter indicating a cause of failure; and wherein the cause of failure is that the UE (106) is temporarily unavailable.

8. The method (600) according to claim 6 or 7, further comprising: - Receive (S602) a subscription regarding a failure event from the fourth network function (104), and wherein, the third message is transmitted in response to the failure event.

9. The method (600) according to claim 8, further comprising: - After the expiration of the retry time after the third, receive (S604) from the fourth network function (104) a fourth message for retrying to configure application or service information; and - In response to the fourth message, transmit (S605) to the second network function (102) a fifth message for retrying a failed policy update or sending a change of cache.

10. The method (600) according to claim 9, wherein, the second message is a session management policy control update request message; wherein, the third message is an event report message; wherein, the fourth message is an application / service information configuration message; or wherein, the fifth message is a session management policy control update notification request message.

11. The method (600) according to claim 10, wherein, the session management policy is a policy and charging control (PCC) rule.

12. A method (700) executed by a fourth network function (104) implementing an application function (AF), comprising: - Receive (S702) from a third network function (103) implementing a policy control function (PCF) a third message, the third message including a third parameter indicating a retry time after the third, wherein, the retry time after the third indicates that the fourth network function (104) suppresses transmitting messages to the third network function (103) during the retry time after the third.

13. The method (700) according to claim 12, further comprising: - Start (S703) a retry timer according to the third parameter to suppress transmitting messages to the third network function (103) while the retry timer is running.

14. The method (700) according to claim 12 or 13, wherein, the third message further includes a fourth parameter indicating a failure reason; and wherein, the failure reason is that the user equipment (106) is temporarily unavailable.

15. The method (700) according to any one of claims 12 to 14, further comprising: - Transmit (S701) a subscription regarding a failure event to the third network function (103), and wherein, the third message is transmitted in response to the failure event.

16. The method (700) according to claim 15, further comprising: After the expiration of the retry timer, transmit (S704) to the third network function (103) a fourth message for retrying to configure application or service information.

17. The method (700) according to claim 16, wherein, the third message is an event report message; or wherein, the fourth message is a session management policy control update notification request message.

18. The method (700) according to claim 17, wherein, the session management policy is a policy and charging control (PCC) rule.

19. A second network function (102, 800) that implements a session management function (SMF), comprising: - at least one processor (801); and - a non-transitory computer-readable medium (802) coupled to the at least one processor (801), the non-transitory computer-readable medium (802) containing instructions executable by the at least one processor (801), whereby the at least one processor (801) is configured to execute the method (500) according to any one of claims 1-5.

20. A third network function (103, 900) that implements a policy control function (PCF), comprising: - at least one processor (901); and - a non-transitory computer-readable medium (902) coupled to the at least one processor (901), the non-transitory computer-readable medium (902) containing instructions executable by the at least one processor (901), whereby the at least one processor (901) is configured to execute the method (600) according to any one of claims 6-11.

21. A fourth network function (104, 1000) that implements an application function (AF), comprising: - at least one processor (1001); and - a non-transitory computer-readable medium (1002) coupled to the at least one processor (1001), the non-transitory computer-readable medium (1002) containing instructions executable by the at least one processor (1001), whereby the at least one processor (1001) is configured to execute the method (700) according to any one of claims 12-18.

22. A computer-readable medium (802, 902, 1002) comprising computer-readable code that, when running on a device (102, 103, 104, 800, 900, 1000, 1100), causes the device (102, 103, 104, 800, 900, 1000, 1100) to execute the method (500, 600, 700) according to any one of claims 1-18.

23. A computer program product (1102) comprising computer-readable code that, when running on a device (102, 103, 104, 800, 900, 1000, 1100), causes the device (102, 103, 104, 800, 900, 1000, 1100) to execute the method (500, 600, 700) according to any one of claims 1 to 18.

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