METHOD AND APPARATUS FOR SAME EVENT SUBSCRIPTION FOR MULTI-SESSIONS OF ONE UE - Patent application

Abstract

This disclosure proposes a method performed by a first NF implementing a consumer of an event publishing service provided by a second NF implementing a producer of the event publishing service, the method including: receiving a trigger to subscribe to an event of a PDU session of a UE; if the event has not been assigned an event ID, assigning a UE-specific event ID to the event; sending a first request to the second NF to subscribe to the event, the first request including the event ID, and storing a mapping between the event ID and the ID of the PDU session. This method reduces resource waste in the first and second NFs, e.g., reduces messaging and traffic between the two NFs, and saves CPU resources in each of the two NFs.

Description

[Technical field]

[0001] Non-limiting exemplary embodiments of the present disclosure relate generally to the technical field of mobile communication networks, and more particularly to a method and apparatus for same event subscription for multiple sessions of one user equipment (UE). [Background technology]

[0002] This section introduces aspects that may be helpful in improving the understanding of the disclosure. Accordingly, the statements in this section should be read in this light and not understood as admissions about what is or is not in the prior art.

[0003] A network function (NF) of a mobile communication network may provide an event publishing service as a producer of a service, and allow other NFs as consumers of the service to subscribe to the event notification and receive notifications about the event. For example, an access and mobility management function (AMF) as a producer in a 5G network may provide such a service to other NFs as consumers, such as a session management function (SMF), a unified data management (UDM), etc.

[0004] The event publishing service may include three basic operations: a subscribe operation, a notify operation, and an unsubscribe operation. As an example, taking an AMF in a 5G network as a producer of the event publishing service and another NF as a consumer of the event publishing service in the 5G network, the three basic operations are described below.

[0005] I. Subscribe Operation A subscribe operation is initiated by an NF service consumer to an AMF when the NF service consumer needs to create a subscription to monitor at least one event related to the AMF. An NF service consumer may subscribe to multiple events in a subscription. A subscription may be associated with one UE, a group of UEs, or any UE. The NF service consumer requests the creation of a new subscription using an HTTP POST method with the URI of the subscription collection.

[0006] An example of a subscribe operation between an NF service consumer and an AMF is shown in Figure 1.

[0007] In step 1 of Figure 1, the NF service consumer (101) sends a POST request to create a subscription resource in the AMF (102). The payload body of the POST request contains a representation of the individual subscription resource to be created. The request may include an expiration time suggested by the NF service consumer (101) as a hint, representing the time it is desired to keep the subscription active, after which subscribed events will stop generating reports.

[0008] If successful, in step 2a of Figure 1, the request is accepted and the AMF (102) includes in the response message an HTTP Location header providing the location of the newly created resource (subscription) along with a status code 201 indicating that the requested resource has been created. If the NF Service Consumer (101) includes multiple events in an event subscription and some events fail to be subscribed to, the AMF (102) accepts the message and provides the successfully subscribed events in AmfEventSubscription.

[0009] On failure or redirection, one of the HTTP status codes is returned in step 2b of Figure 1. For 4xx / 5xx responses, the message body contains a ProblemDetails structure with a "cause" attribute set to one of the application errors.

[0010] II. Notification behavior A notification service operation is initiated by AMF to send a notification towards the notification URI when a specific event included in the subscription occurs. To send the notification, AMF uses an HTTP POST method that contains, for example, the subscription ID, the event ID of the event that occurred, the notification correlation ID provided by the NF service consumer at the time of the event subscription, and uses the notification URI received at the time of the subscription creation.

[0011] An example of notification operation between an NF service consumer and an AMF is shown in Figure 2.

[0012] In step 1 of FIG. 2, the AMF (202) sends a POST request to send a notification.

[0013] If successful, "204 No content" is returned by the NF Service Consumer (201) in step 2a of FIG.

[0014] Upon failure or redirection, an appropriate HTTP status code is returned indicating the error (eg, "403 Forbidden"), and any additional error information is returned as appropriate, in step 2b of FIG.

[0015] III. Unsubscribe Behavior An unsubscribe operation is initiated by an NF service consumer against AMF to remove an existing subscription previously created by the NF service consumer in AMF. The NF service consumer unsubscribes a subscription using the HTTP DELETE method with the URI of the individual subscription resource to be deleted.

[0016] An example of notification operation between an NF service consumer and an AMF is shown in Figure 3.

[0017] In step 1 of Figure 3, the NF service consumer (301) sends a delete request to delete an existing subscription resource of the AMF (302).

[0018] If successful, the request is accepted in step 2a of FIG. 3 and the AMF (302) responds with a response message with status code 204 indicating that the resource identified by the subscription ID has been successfully deleted.

[0019] On failure or redirection, one of the HTTP status codes is returned in step 2b of Figure 3. For 4xx / 5xx responses, the message body contains a ProblemDetails structure with a "cause" attribute set to one of the application errors.

[0020] In addition to providing the event publishing service, as specified in 3GPP (registered trademark) Technical Specification (TS) 29.518, if both the AMF and the UDM support the "ESSYNC" function, the AMF may initiate synchronization of event subscriptions with the UDM for a specific UE during the evolved packet system (EPS) to fifth generation system (5GS) mobility registration procedure if UE-specific event subscriptions from the UDM are available in the UE context.

[0021] To start the synchronization of event subscriptions, the AMF must include the event subscription information in the notification request when sending a notification of subscription change to the UDM. If a subscription change notification is not required, for example, when the UE registers to the same AMF after moving from an evolved packet system (EPS), the AMF may send the notification to the subscription change notification URI. The notification request in this case contains only the event subscription information and does not contain the event report list.

[0022] AMF includes only active event subscriptions from the UDM Event Publishing Service for a specific UE in the event subscription information, i.e. subscriptions targeted to a specific UE (not a group of UEs or any UE) and each subscribed event with a reference ID (i.e. the "refId" field as defined in "Table 6.2.6.2.3-1: Definition of type AmfEvent" in TS 29.518). For each active subscription the following information is included: -The URI of the subscription resource in AMF; -Notification correlation ID of the subscription; -A list of reference IDs, one for each event in the subscription; - Optionally, the URI of the old subscription resource on the source AMF, if the subscription ID changed during the mobility procedure.

[0023] When the UDM receives event subscription information from the AMF, the UDM uses the reference ID and notification correlation ID to compare the AMF's active event subscriptions with the active UDM event publishing subscriptions, and does the following: -If an event is detected by AMF but does not exist in AMF, the UDM subscribes to the event in AMF by creating a new AMF event subscription or updating an existing AMF event subscription. -If the event is present in the AMF but not in the UDM, the UDM unsubscribes to the event from the AMF by deleting or updating the AMF event subscription.

[0024] According to the latest version of TS29.518, the reference ID is specifically designed for event monitoring subscriptions from UDM, but it cannot be excluded that other NFs may use it for internal AMF event subscriptions. Summary of the Invention [Problem to be solved by the invention]

[0025] In some cases, it is necessary to subscribe to an event for a PDU session of a UE. Thus, a first NF acting as a consumer of an event publishing service in a mobile communication network may send a request to a second NF acting as a producer of the event publishing service to subscribe to an event of a PDU session of a UE. The request to subscribe to an event of a PDU session may be triggered by the first NF itself or by another NF according to traffic requirements, operator requirements, and / or other requirements defined by technical specifications of the mobile communication network.

[0026] However, the inventors of the present disclosure have discovered that if a first NF wants to subscribe to the same event for multiple PDU sessions of the same UE, the following problem exists.

[0027] The first NF acting as a consumer sends requests to the second NF acting as a producer to subscribe to the same event for each of the UE's multiple PDU sessions, i.e. multiple requests are sent from the first NF to the second NF and when an event occurs the second NF will send multiple reports of the same event to the first NF, e.g. causing resource waste.

[0028] For example, in an SMF that manages PDU sessions in a 5G network, one UE may have M PDU sessions. If the SMF wants to subscribe to the same event of the M PDU sessions of the UE from the AMF of the 5G network, the SMF will send M requests to the AMF, and the AMF will send M reports of the same event to the SMF, causing the following: (1) Increased message exchange between SMF and AMF. (2) Increased traffic load between AMF and SMF. (3) Increased CPU resources consumed by AMF for generating and sending reports for the same event. (4) Increased CPU resources consumed by SMF to receive and process reports of the same event.

[0029] It is an object of the present disclosure to solve or mitigate the above problems. [Means for solving the problem]

[0030] According to a first aspect of the present disclosure, the object is achieved by a method in a first network function (NF) for implementing a consumer of an event publishing service provided by a second NF for implementing a producer of the event publishing service, the method comprising: receiving a trigger for subscribing to an event of a protocol data unit (PDU) session of a user equipment unit (UE); if the event has not been assigned an event identifier (ID), assigning a UE-specific event ID to the event and sending a first request to the second NF for subscribing to the event including the event ID; and storing a mapping between the event ID and an ID of the PDU session.

[0031] According to a second aspect of the present disclosure, the object is achieved by a first Network Function (NF) implementing a consumer of an event publishing service provided by a second Network Function (NF) implementing a producer of the event publishing service, the first NF comprising: a receiving unit for receiving a trigger for subscribing to an event of a Protocol Data Unit (PDU) session of a user equipment unit (UE); an allocating and sending unit for allocating a UE specific event ID to the event if the event has not been assigned an event identifier (ID) and sending a first request to the second NF for subscribing to the event, the first request including the event ID; and a storing unit for storing a mapping between the event ID and an ID of the PDU session.

[0032] According to a third aspect of the present disclosure, the object is achieved by a first Network Function (NF) implementing a consumer of an event publishing service provided by a second NF implementing a producer of the event publishing service, the first NF comprising a processor and a memory storing instructions which, when executed on the processor, cause the first NF to receive a trigger for subscribing to an event of a protocol data unit (PDU) session of a user equipment unit (UE); if the event has not been assigned an event identifier (ID), assign a UE-specific event ID to the event and send a first request to the second NF to subscribe to the event including the event ID; and store a mapping between the event ID and the ID of the PDU session.

[0033] According to a fourth aspect of the present disclosure, the object is achieved by a machine-readable medium storing instructions which, when executed on a first NF, cause the first NF to perform a method according to the first aspect.

[0034] According to a fifth aspect of the present disclosure, the object is achieved by a method in a second NF implementing a producer providing an event publishing service to a first NF implementing a consumer of the event publishing service, the method comprising: receiving a request to subscribe to an event from the first NF, the request including an event ID of the event; storing the event ID; and, if the event occurs, sending a report of the event to the first NF, the report including the event ID.

[0035] According to a sixth aspect of the present disclosure, the object is achieved by a second Network Function (NF) implementing a producer providing an event publishing service to a first NF implementing a consumer of the event publishing service, the second NF comprising a receiving unit configured to receive a request to subscribe to an event from the first NF, the request including an event ID of the event, a storing unit configured to store the event ID, and a sending unit configured to send a report of the event to the first NF, including the event ID, if the event occurs.

[0036] According to a seventh aspect of the present disclosure, the object is achieved by a second Network Function (NF) implementing a producer providing an event publishing service to a first NF implementing a consumer of the event publishing service, the second NF comprising a processor and a memory storing instructions which, when executed on the processor, cause the second NF to receive a request to subscribe to an event from the first NF, the request including an event ID of the event, store the event ID, and, if the event occurs, send a report of the event to the first NF, the report including the event ID.

[0037] According to an eighth aspect of the present disclosure, the object is achieved by a machine-readable medium storing instructions which, when executed in 2NF, cause 2NF to perform the method according to the fifth aspect.

[0038] According to a ninth aspect of the present disclosure, the present disclosure also provides a method in a second network function (NF) implementing a producer providing an event publishing service to a first network function (NF) implementing a consumer of the event publishing service, the method including: receiving a request to subscribe to an event from the first NF; if the event occurs, sending a report of the event to the first NF; and if the third NF acts as a new producer providing the event publishing service, notifying the third NF of subscription information of the event, where the first NF is a Session Management Function (SMF) or a first UDM, the second NF is an Access and Mobility Management Function (AMF), and the third NF is another AMF, where if the other AMF and the second UDM both support an "ESSYNC" function, the subscription information further includes an indicator indicating whether the other AMF needs to synchronize the subscription of the event with the second UDM, and the second UDM is the first UDM or another UDM.

[0039] According to a tenth aspect of the present disclosure, the present disclosure also provides a second Network Function (NF) implementing a producer providing an event publishing service to a first NF implementing a consumer of the event publishing service, the second NF comprising: a receiving unit for receiving a request to subscribe to an event from the first NF; a sending unit for sending a report of the event to the first NF when the event occurs; and a notification unit for notifying the third NF of subscription information of the event when the third NF acts as a new producer providing the event publishing service, wherein the first NF is a Session Management Function (SMF) or a first UDM, the second NF is an Access and Mobility Management Function (AMF), and the third NF is another AMF, and when the other AMF and the second UDM both support an "ESSYNC" function, the subscription information further includes an indicator indicating whether the other AMF needs to synchronize the subscription of the event with the second UDM, and the second UDM is the first UDM or another UDM.

[0040] According to an eleventh aspect of the present disclosure, the present disclosure also provides a second Network Function (NF) implementing a producer providing an event publishing service to a first NF implementing a consumer of the event publishing service, the second NF including a processor and a memory storing instructions, which when executed on the processor cause the second NF to perform the following: receive a request to subscribe to an event from the first NF; if the event occurs, send a report of the event to the first NF; and if the third NF acts as a new producer providing the event publishing service, notify the third NF of subscription information of the event, wherein the first NF is a Session Management Function (SMF) or a first UDM, the second NF is an Access and Mobility Management Function (AMF), and the third NF is another AMF, and if the other AMF and the second UDM both support an "ESSYNC" function, the subscription information further includes an indicator indicating whether the other AMF needs to synchronize the subscription of the event with the second UDM, and the second UDM is the first UDM or another UDM.

[0041] According to a twelfth aspect of the present disclosure, the present disclosure also provides a machine-readable medium having stored thereon instructions which, when executed in 2NF, cause the 2NF to perform a method according to the ninth aspect.

[0042] According to the present invention, when the same event needs to be subscribed to in multiple sessions, the first NF will send only one request and the second NF will send only one report when the event occurs, thus reducing message exchange and traffic between the two NFs and reducing resource waste, such as saving CPU resources in each of the two NFs.

[0043] The above and other aspects, features, and advantages of the present disclosure will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings, in which like reference numbers or letters are used to indicate like or equivalent elements. The drawings are presented to facilitate a better understanding of the embodiments of the present disclosure and are not necessarily drawn to scale. [Brief description of the drawings]

[0044] [Figure 1] A diagram showing an example of a subscribe operation between an NF service consumer and an AMF. [Diagram 2] A diagram showing an example of notification operation between an NF service consumer and an AMF. [Diagram 3] A diagram showing an example of notification operation between an NF service consumer and an AMF. [Figure 4] 1 is a flowchart of a method in 1NF for implementing a consumer of an event publishing service in accordance with the present disclosure. [Diagram 5] 1 is a flowchart of a method in 2NF for implementing a producer that provides an event publishing service in accordance with the present disclosure. [Figure 6] FIG. 1 illustrates an example of 1NF and 2NF processing and signaling exchanges in accordance with the present disclosure. [Figure 7] FIG. 1 is a schematic block diagram of a First NF in accordance with the present disclosure. [Figure 8] FIG. 1 is a schematic block diagram of 2NF in accordance with the present disclosure. [Figure 9] FIG. 13 is another schematic block diagram of a 1NF in accordance with the present disclosure. [Figure 10] FIG. 13 is another schematic block diagram of a 2NF in accordance with the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045]

[0023] The embodiments of the present disclosure are described in more detail below with reference to the accompanying drawings. However, the embodiments herein may be embodied in many different forms and should not be construed as limiting the scope of the appended claims.

[0046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The singular forms are intended to include the plural forms unless the context clearly indicates otherwise. As used herein, the terms "including," "comprising," and / or "having" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0047] Additionally, the use of ordinal numbers such as "first," "second," "third," etc., herein to modify elements does not, in and of itself, indicate a priority, an ordering of one element relative to other elements, or a temporal order in which the operations of a method are performed, but is used merely as a label to distinguish one element having a particular name from other elements having the same name (however ordinal numbers are used).

[0048] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood. Furthermore, terms used herein should be interpreted to have a meaning consistent with their meaning in the context of this specification and related art, and should not be interpreted in an ideal or overly formal sense unless expressly defined herein.

[0049] A flowchart of a method in a first NF for implementing a consumer of an event publishing service provided by a second NF for implementing a producer of the event publishing service is shown in Fig. 4. The method 400 includes a step 401 of receiving a trigger for subscribing to an event of a PDU session of a UE, a step 402 of assigning a UE-specific event ID for the event if the event has not been assigned an event ID and sending a first request to the second NF for subscribing to the event, the request including the event ID, and a step 403 of storing a mapping between the event ID and the ID of the PDU session.

[0050] In one embodiment, the method 400 further includes receiving a report of the event from the second NF, the report including the event ID, and forwarding the report to one or more PDU sessions of the UE that have subscribed to the event according to a mapping between the event ID and IDs of the one or more PDU sessions of the UE.

[0051] In one embodiment, the method 400 further includes receiving a trigger to unsubscribe to an event of the UE's PDU session, deleting a mapping between the event ID and the ID of the PDU session of the event to be unsubscribed, and if there is no mapping between the event ID and the ID of the PDU session in the first NF, deleting the event ID and sending a second request to the second NF to unsubscribe to the event.

[0052] In one embodiment, the mappings are stored in a 1NF mapping table.

[0053] In one embodiment, the first NF is an SMF or a UDM and the second NF is an AMF.

[0054] In a further embodiment, the first request is a Namf_EventExposure_Subscribe request, the report is carried in a Namf_EventExposure_Notify request, and the second request is a Namf_EventExposure_UnSubscribe request.

[0055] In a further embodiment, the event ID is carried in the existing "refId" field or a newly defined field in Namf_EventExposure_Subscribe requests and reports.

[0056] A flowchart of a method 500 in a 2NF of implementing a producer providing an event publishing service to a 1NF implementing a consumer of the event publishing service includes step 501 of receiving a request to subscribe to an event from the 1NF, the request including an event ID for the event, step 502 of storing the event ID, and step 503 of sending a report of the event to the 1NF, when the event occurs, the report including the event ID.

[0057] In one embodiment, the method 500 further includes notifying 3NF of subscription information for the event, including the event ID, if 3NF acts as a new producer providing the event publishing service.

[0058] In one embodiment, the first NF is an SMF or a first UDM, and the second NF is an AMF.

[0059] In a further embodiment, the request is a Namf_EventExposure_Subscribe request and the report is carried in a Namf_EventExposure_Notify request.

[0060] In a further embodiment, the event ID is carried in the existing "refId" field or a newly defined field in Namf_EventExposure_Subscribe requests and reports.

[0061] In a further embodiment, the 3NF is another AMF and the subscription information includes the event ID in an existing "refId" field.

[0062] In a further embodiment, if the other AMF and the second unified data management (UDM) both support the "ESSYNC" function, the subscription information further includes an indicator indicating that the subscription to the event does not need to be synchronized with the second UDM, which may be the first UDM, or the second UDM may be different from the first UDM.

[0063] Both 1NF and 2NF may be implemented as network elements on dedicated hardware, as software instances or firmware running on the hardware, as virtualized functions instantiated on a suitable platform (such as a cloud infrastructure), or as any combination thereof.

[0064] Further embodiments are now described in relation to an SMF (as a consumer) and an AMF (as a producer) in a 5G network, as shown in FIG. 6. Although further embodiments herein are described in relation to an SMF, an AMF, and a 5G network, it is understood that the embodiments may also be applied to other NFs and / or other mobile communication networks, if the same issues exist in the mechanism for requesting subscriptions for multiple sessions for one UE. It is also understood that, although specific terms are used in the embodiments, the embodiments are not limited to those specific terms and may be applied to all similar entities. For example, "user equipment" / "UE" in this specification may refer to, for example, a user terminal, a station, a terminal, a terminal node, etc.

[0065] FIG. 6 shows an example of processing and signaling interaction in the first NF and the second NF according to the present disclosure, where the SMF (601) is an example of the first NF and the AMF (602) is an example of the second NF. Note that only two PDU sessions are used as an example in FIG. 6, but it does not mean that at most two PDU sessions can be involved in the present invention. The present invention can include more PDU sessions, and the maximum number of PDU sessions of a UE depends on the limitations of 3GPP, such as (1) the maximum number of PDU sessions of a UE defined in 3GPP, and (2) the number of PDU sessions of a UE simultaneously connected to the same SMF.

[0066] I. An event is subscribed to for the first time for a UE's PDU session. Step 1: The SMF, which is a consumer of the event publishing service, receives a trigger to subscribe to an event of a UE's PDU session (in this example its ID is "session_id1"). The trigger may come from the SMF itself or from another NF according to traffic requirements, operator requirements and / or other requirements defined by the technical specifications of the mobile communication network.

[0067] Step 2: The SMF determines whether the event is currently assigned an event ID. In this example, the event is subscribed to for the first time. Thus, the SMF detects that the event is not currently assigned an event ID, assigns a UE-specific event ID for the event (in this example "identifier1"), and stores the mapping between the event ID and the ID of the PDU session, for example in a mapping table. Each ID of the PDU session uniquely identifies one session of the same UE in the same consumer or one session of the same UE, for example a 3GPP-defined PDU session ID or any privately defined identifier. It can be understood that the mapping can be stored in a different data structure than the mapping table. In any case, as is clear from Fig. 6, the mapping table stores the mapping between "identifier1" and "session_id1".

[0068] Step 3: The SMF sends a first request to subscribe to the event to the AMF, which is a producer of the event publishing service, where the first request includes the event ID. In this example, the first request may be a Namf_EventExposure_Subscribe request. In a further embodiment, the event ID is carried in the existing "refId" field or a newly defined field of the Namf_EventExposure_Subscribe request.

[0069] In the example of Fig. 6, the mapping between the event ID and the ID of the PDU session is stored before sending the first request, but it should be noted that the mapping can be stored after sending the first request. The order of storing and sending does not affect the technical effect of the present invention.

[0070] Step 4: The AMF may accept the first request by sending a response to the SMF, and the event ID may or may not be included in the response. In this example, the response may be a Namf_EventExposure_Subscribe response. If the present invention is applied to other mobile communication networks, there may be no such response.

[0071] II. The same event is subscribed to in another PDU session for the same UE. Step 5: The SMF receives another trigger to subscribe to the same event in another PDU session of the same UE (in this example, its ID is "session_id2").

[0072] Step 6: The SMF finds that the event has been assigned an event ID, i.e., the SMF has previously subscribed to the same event from the AMF for this UE. Thus, the SMF does not need to send another request to the AMF to subscribe to the event, but only stores the mapping between the event ID and the ID of the PDU session, for example in a mapping table, which can reduce signaling. As mentioned above, the mapping can be stored in a different data structure than the mapping table. In any case, as is clear from Fig. 6, the mapping table stores the mapping between "identifier1" and {"session_id1", "session_id2"}.

[0073] III. The AMF sends a report of the event to the SMF. Step 7: If an event occurs, the AMF sends a report of the event to the SMF. In the report, the event ID (in this example "identifer1") is included in the report. In this example, the report can be carried in a Namf_EventExposure_Notify request. In a further embodiment, the event ID is carried in the existing "refId" field or a newly defined field in the report.

[0074] According to the present disclosure, since the event ID is specific to a UE, it can be understood that multiple event IDs may be present in the report if multiple event IDs were previously assigned to events for PDU sessions from multiple UEs.

[0075] Step 8: The SMF may acknowledge receipt of the report by sending a response to the AMF. In this example, the response may be a Namf_EventExposure_Notify response. If the present invention is applied to other mobile communication networks, there may be no such response.

[0076] IV.SMF forwards the event report to the corresponding PDU session. Step 9: The SMF uses the event ID (in this example "identifer1") in the report received from the AMF and a local mapping table to determine the PDU sessions that the report is for. In this example, the report containing the event ID "identifer1" is for the PDU session with ID "session_id1" and the PDU session with ID "sesson_id2" according to the mapping table.

[0077] If there are multiple event IDs in a report, the SMF uses each event ID and the corresponding mapping table to determine the PDU session that the report covers.

[0078] Step 10: The SMF forwards the report to the corresponding PDU session. In this example, the report is forwarded to the PDU session with ID "session_id1" and the PDU session with ID "sesson_id2".

[0079] Compared with per-session subscription, there is only one report from the AMF for events of multiple PDU sessions of one UE, thus saving signaling. If M PDU sessions share the same event subscription, the signaling overhead of the report can be reduced by (M-1) / M.

[0080] The V.UE's PDU session event is unsubscribed. Step 11: The SMF receives a trigger to unsubscribe the event of the UE's PDU session (whose ID is "session_id1" in this example). The trigger may come from the SMF itself or from another NF according to traffic requirements, operator requirements, and / or other requirements defined by the technical specifications of the mobile communication network.

[0081] Step 12: The SMF deletes the mapping between the event ID ("identifier1" in this example) and the ID of the PDU session to which the event is unsubscribed ("session_id1" in this example), for example, by deleting the PDU session ID "session_id1" from the mapping table, so that only the mapping between the event ID "identifier1" and the session ID "session_id2" is retained in the mapping table.

[0082] Compared to per-session subscription, in this situation there is no need to send a request to AMF to unsubscribe from the event, thus reducing the signaling overhead for unsubscribing.

[0083] VI. The AMF sends a further report of the event to the SMF. Step 13: If the event occurs again, the AMF sends a further report of the event to the SMF. The further report includes the event ID (in this example "identifer1"). In this example, the further report may be carried in a Namf_EventExposure_Notify request. In a further embodiment, the event ID is carried in the existing "refId" field or a newly defined field in the further report.

[0084] According to the present disclosure, since the event ID is specific to a UE, it can be understood that multiple event IDs may be present in the further report if multiple event IDs were previously assigned to events of PDU sessions from multiple UEs.

[0085] Step 14: The SMF may acknowledge receipt of the further report by sending a response to the AMF. In this example, the response may be a Namf_EventExposure_Notify response. If the present invention is applied to other mobile communication networks, there may be no such response.

[0086] VII.SMF forwards further event reports to the corresponding PDU session. Step 15: The SMF uses the event ID (in this example "identifer1") in the further report received from the AMF and a local mapping table to determine the PDU session that the further report is intended for. In this example, the further report with event ID "identifer1" is intended for the PDU session with ID "sesson_id2" according to the mapping table.

[0087] If there are multiple event IDs in the further report, the SMF uses each event ID and the corresponding mapping table to determine the PDU session that is the subject of the further report.

[0088] Step 16: The SMF forwards the further report to the corresponding PDU session. In this example, the further report is forwarded only to the PDU session with ID "session_id2".

[0089] VII. The UE is unsubscribed to an event of another PDU session. Step 17: The SMF receives a trigger to unsubscribe the event of another PDU session of the UE (in this example, its ID is "session_id2"). The trigger may come from the SMF itself or from another NF according to traffic requirements, operator requirements, and / or other requirements defined by the technical specifications of the mobile communication network.

[0090] Step 18: The SMF deletes the mapping between the event ID ("identifier1" in this example) and the ID of the PDU session to which the event is unsubscribed ("session_id2" in this example), for example, by deleting the PDU session ID "session_id2" from the mapping table, so that there is no mapping for the event ID "identifier1" in the mapping table in this example. If the SMF determines that there is no mapping for the event ID "identifier1" in the mapping table, the SMF must also delete the event ID ("identifier1" in this example).

[0091] Step 19: Because there is no PDU session to which the event needs to be subscribed, the SMF sends a second request to the AMF to unsubscribe the event. In this example, the second request is a Namf_EventExposure_UnSubscribe request.

[0092] Step 20: The AMF may accept the second request by sending a response to the AMF. In this example, the response may be a Namf_EventExposure_UnSubscribe response. When the present invention is applied to other mobile communication networks, there may be no such response.

[0093] It can be understood that if the 3NF is to act as a new producer providing an event publishing service, the 2NF needs to inform the 3NF of the event subscription information including the event ID. For example, if a new AMF acts as a new producer providing an event publishing service, the AMF needs to inform the new AMF of the event subscription information including the event ID. The 3NF (i.e., the new producer) works similarly to the 2NF, e.g., the new producer also stores the event ID, and when an event occurs, it sends a report including the event ID of the event to the 1NF.

[0094] However, if the first NF is an NF other than the UDM, for example, if the first NF is an SMF, when the subscription information includes an event ID in the existing "refId" field and both the new AMF and the UDM support the "ESSYNC" function, the new AMF may initiate unnecessary synchronization of the event subscription with the UDM for a particular UE when the new AMF determines that the "refId" field is not empty. To avoid this unnecessary subscription synchronization, the subscription information may further include an indicator of the new AMF indicating that the event subscription does not need to be synchronized with the UDM. For example, a new information element (IE) "eventSyncInd" may be defined in the "AmfEventSubscription" type specified in 3GPP TS29.518 as an indicator. The value "true" of the IE "eventSyncInd" may mean that the event subscription synchronization with the UDM is performed in the subscription, and the absence of the IE "eventSyncInd" or the value "false" of the IE "eventSyncInd" may mean that the event subscription synchronization with the UDM is not required in the subscription. Therefore, the absence of "eventSyncInd" in the IE or the IE "eventSyncInd" with the value "false" may be used as an indicator of the new AMF indicating that it does not need to synchronize event subscriptions with the UDM. Furthermore, according to some traffic requirements, if both the new AMF and the UDM support the "ESSYNC" function and the 1st NF is a UDM or another UDM, the new AMF needs to start synchronizing event subscriptions with the UDM, in which case the indicator in the subscription information needs to be set to a value indicating that the new AMF synchronizes event subscriptions with the UDM (e.g., the value of the IE "eventSyncInd" is set to "true"). In any case, if the 3rd NF is a new AMF, the subscription information may optionally include an indicator indicating whether the new AMF needs to synchronize event subscriptions with the UDM.

[0095] 7 shows a schematic block diagram of a first NF 700 according to the present disclosure. The first NF 700 implements a consumer of an event publishing service provided by a second NF that implements a producer of the event publishing service. The first NF 700 includes a receiving unit 701 for receiving a trigger to subscribe to an event of a PDU session of a UE, an allocating and sending unit 702 for allocating a UE-specific event ID for the event if the event has not been assigned an event ID, and sending a first request to the second NF to subscribe to the event, the request including the event ID, and a storing unit 703 for storing a mapping between the event ID and the ID of the PDU session.

[0096] 8 shows a schematic block diagram of a second NF 800 according to the present disclosure. The second NF implements a producer that provides an event publishing service to a first NF that implements a consumer of the event publishing service. The second NF 800 includes a receiving unit 801 that receives a request to subscribe to an event from the first NF, the request including an event ID of the event, a storing unit 802 that stores the event ID, and a sending unit 803 that sends a report of the event, including the event ID, to the first NF when the event occurs.

[0097] The first NF700 and the second NF800 described in this specification may be implemented by various units, so that each of the first NF700 and the second NF800 implementing one or more functions described in the embodiment may include not only the units shown in the corresponding figures but also other units for implementing the one or more functions. Furthermore, each of the first NF700 and the second NF800 may include a single unit configured to perform two or more functions, or separate units for each separate function. Furthermore, the units may be implemented in hardware, firmware, software, or any combination thereof.

[0098] It will be understood that the blocks of the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented by computer program instructions that can be provided to a processor of a general purpose computer, special purpose computer, and / or other programmable data processing apparatus to execute the instructions via the processor of the computer and / or other programmable data processing apparatus to produce a machine that creates means for implementing the functions / acts identified in the block diagrams and / or flowchart blocks.

[0099] Additionally, the solutions of the present disclosure may take the form of a computer program on a memory having computer usable or computer readable program code embodied in a medium for use by or associated with an instruction execution system. In the context of this document, a memory may be any medium adapted to contain, store, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device.

[0100] Therefore, the present disclosure also provides a first NF 900 including a processor 901 and a memory 902 as shown in Fig. 9. In the first NF 900, the memory 902 stores instructions that, when executed by the processor 901, cause the first NF 900 to execute the first NF method described above in the embodiment. The present disclosure also provides a second NF 1000 including a processor 1001 and a memory 1002 as shown in Fig. 10. In the second NF 1000, the memory 1002 stores instructions that, when executed by the processor 1001, cause the second NF 900 to execute the second NF method described above in the embodiment.

[0101] The present disclosure also provides a machine-readable medium (not shown) having stored thereon instructions that, when executed on a 1NF, cause the 1NF to perform the 1NF method described in the above embodiment. The present disclosure also provides a machine-readable medium (not shown) having stored thereon instructions that, when executed on a 2NF, cause the 2NF to perform the 2NF method described in the above embodiment.

[0102] Although this specification contains many specific implementation details, these should not be construed as limitations on the scope of the implementation or claimed subject matter, but rather as descriptions of features specific to particular embodiments of a particular implementation. Certain features described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as acting in a particular combination, and may even be initially claimed as such, one or more features from a claimed combination may, in some cases, be deleted from the combination, and the claimed combination may be directed to subcombinations or variations of the subcombination.

[0103] It will be obvious to those skilled in the art that as technology advances, the concept of the present invention can be implemented in various ways. The above-mentioned embodiments are given to illustrate, not to limit, the present disclosure, and it should be understood that modifications and variations can be resorted to without departing from the spirit and scope of the present disclosure, as easily understood by those skilled in the art. Such modifications and variations are deemed to be within the scope of the present disclosure and the appended claims. The scope of protection of the present disclosure is defined by the appended claims.

[0104] Indeed, in accordance with this disclosure, the inventors have proposed several modifications to the following content of 3GPP TS 29.518, the modifications being indicated in bold and underlined text:

[0105] "5.3.2.2.2 Creating a Subscription A subscribe service operation is initiated by an NF service consumer, such as an NEF, to an AMF when the NF service consumer needs to create a subscription to monitor at least one event related to the AMF. An NF service consumer may subscribe to multiple events in one subscription. A subscription may be associated with one UE, a group of UEs, or any UE. The NF service consumer requests the creation of a new subscription by using the HTTP POST method with the URI of the subscription collection. The NF service consumer MUST include the following information in the HTTP message body: - NFID indicating the identifier of the network function instance initiating the subscription; -Subscription targets, which indicate the monitored targets in one of the following types: - a specific UE identified by SUPI, PEI or GPSI; - a group of UEs identified by a group identifier; - Any UE identified by the "anyUE" flag. - a notification URI indicating the address to which event notifications generated by the subscription should be delivered; -notification correlation ID indicating the correlation identifier carried in the event notifications generated by the subscription; - A list of subscribed events; - The event type for each event as specified in section 5.3.1. An NF service consumer can include the following information in the HTTP message body: - Instant report per event flag indicating that an instant report should be generated under the current event conditions; -Event triggers, which indicate how the event is reported (one-time report or continuous report); - Maximum number of reports, which defines the maximum number of reports before an event subscription is no longer present; - an expiration time, which defines the maximum period after which an event subscription may no longer exist; - a sampling rate that defines a random subset of UEs among the target UEs, such that the AMF will only report events relevant to the selected subset of UEs; -Per-event periodic report flag, indicating that reports are generated periodically; - Repeat period to define the period of periodic reports; -Applicable event filters on a per-event basis that define additional options on how the event is reported; - A per-event reference ID indicating the value of the reference ID associated with the monitored event. If specified, the reference ID will be included in reports triggered by the event.

[0106] [Table 1]

[0107] 1. The NF service consumer sends a POST request to create a subscription resource in AMF. The payload body of the POST request contains a representation of the individual subscription resource to be created. The request represents the time it is desired to keep the subscription active, after which subscribed events will stop generating reports, and may include an expiration time suggested by the NF service consumer as a hint. 2a. If successful, the request is accepted and the AMF includes an HTTP Location header in the response message providing the location of the newly created resource (subscription) along with a status code of 201 indicating that the requested resource has been created. If the NF service consumer included multiple events in the event subscription and some events failed to be subscribed to, the AMF accepts the message and provides the successfully subscribed events in AmfEventSubscription. If the NF service consumer included an immediateFlag with value "true" in the event subscription, the AMF includes the current state of the subscribed event, if available (e.g. if the subscribed event is LOCATION_REPORT, the last known location information is included). If an event with immediateFlag set to "true" is subscribed to by the NF service consumer on behalf of 3NF and notifications are sent directly to 3NF, i.e. if subsChangeNotifyUri is included in the event subscription, the current state of the subscribed event is not included in the response. The AMF then sends a notification to 3NF containing the current state of the subscribed event. If the NF service consumer sets the event reporting option to ONE_TIME and the AMF includes the current state of the subscribed event in the response, the AMF shall not send any further event notifications for the events specified in the AmfCreateEventSubscription parameters. If the NF service consumer sets the event reporting option to ONE_TIME, the subscribed event to LOCATION_REPORT and the immediateFlag is set to false or is not present, the AMF shall send an event notification informing of the UE's current location after subscription. The response may contain an expiration time determined by the AMF based on the operator's policies and taking into account the expiration time included in the request, after which the subscription becomes invalid. If the NF service consumer wants to continue receiving notifications after the subscription expiration time has passed, it needs to create a new subscription in the AMF. The AMF should not set the same expiration time for many subscriptions to avoid all subscriptions expiring at the same time and having to be recreated. If an expiration time is not included in the response, the NF service consumer shall consider the subscription valid without expiration time. If the subscription contains a sampling ratio ("sampRatio") attribute, the AMF selects a random subset of UEs among the target UEs according to the sampling ratio and reports only events relevant to the selected subset of UEs. If both the AMF and the NF consumer (i.e., UDM) support the "ESSYNC" feature and the subscription is targeted to a specific UE, the AMF locally includes the "eventSyncInd" IE with value "true" in the created subscription. The "eventSyncInd" IE is not included in the event subscription sent to the NF consumer. If the new AMF supports the "ESSYNC" feature, the "eventSyncInd" IE with value "true" is included in the UE context during the inter-AMF mobility procedure. In the event of failure or redirection, one of the HTTP status codes listed in Table 6.2.3.2.3.1-3 is returned. For 4xx / 5xx responses, the message body contains a ProblemDetails structure with the "cause" attribute set to one of the application errors listed in Table 6.2.3.2.3.1-3. 5.3.2.4.2 Event subscription synchronization for a specific UE When both the AMF and the UDM support the "ESSYNC" functionality, the AMF may initiate synchronization of event subscriptions with the UDM for a specific UE during the EPS-to-5GS mobility registration procedure if UE-specific event subscriptions from the UDM are available in the UE context (see clause 4.11.5.2 of 3GPP TS 23.502 [3]). To start the synchronization of event subscriptions, the AMF must include the event subscription information in the notification request when sending a notification of subscription change to the UDM. If subscription change notification is not required (for example, when the UE registers to the same AMF after moving from EPS), the AMF may send the notification to the subscription change notification URI. The notification request in this case contains only the event subscription information and does not contain the event report list. The AMF SHALL include in the event subscription information only those active event subscriptions that are subject to event subscription synchronization with the UDM (determined as defined in Section 5.3.2.2.2). For each active subscription, include the following information: -The URI of the subscription resource in AMF; -Notification correlation ID for the subscription -A list of reference IDs, one for each event in the subscription - Optionally, the URI of the old subscription resource on the source AMF, if the subscription ID changed during the mobility procedure. When the UDM receives event subscription information from the AMF, the UDM uses the reference ID and notification correlation ID to compare the AMF's active event subscriptions with the active UDM event publishing subscriptions, and does the following: - if an event is detected by AMF but does not exist in AMF, the UDM subscribes to the event in AMF by creating a new AMF event subscription or updating an existing AMF event subscription; -If the event is present in the AMF but not in the UDM, the UDM unsubscribes to the event from the AMF by deleting or updating the AMF event subscription.

[0108] [Table 2] [Table 3]

[0109] 6.2.8 Capability Negotiation The capability negotiation mechanism specified in clause 6.6 of 3GPP TS 29.500 [4] is used between the AMF and the NF service consumer to negotiate optional capabilities that apply to the Namf_EventExposure service, if any. An NF service consumer MUST indicate any optional features it supports for the Namf_EventExposure service by including a supportedFeature attribute in the payload of the HTTP request message for creating a subscription resource. The AMF determines the functions supported by a service operation, as specified in clause 6.6 of 3GPP TS 29.500 [4], and indicates the supported functions by including a supportedFunctions attribute in the payload of the HTTP response for creating a subscription resource. The syntax of the SupportedFeature attribute is defined in section 5.2.2 of 3GPP TS 29.571 [6]. The Namf_EventExposure service defines the following functions:

[0110] [Table 4]

[0111] [Table 5]

[0112]

Table 6

Table 7

Table 8

[0113]

Table 9

Table 10

Table 11

Claims

1. A method (400) in a first Network Function (NF) implementing a consumer of an event publishing service provided by a second NF implementing a producer of said event publishing service, comprising: Receiving a trigger for subscribing to a protocol data unit (PDU) session event of a user equipment (UE) (401); if no event identifier (ID) is assigned for the event, assigning an event ID unique to the UE for the event and sending a first request to the second NF to subscribe to the event, the first request including the event ID (402); storing (403) a mapping between the event ID and the ID of the PDU session; The method includes:

2. 2. The method (400) of claim 1, further comprising: receiving a report of the event from the second NF, the report including the event ID; forwarding the report to one or more PDU sessions of the UE subscribing to the event according to a mapping between the event ID and the ID of the one or more PDU sessions; The method includes:

3. 3. The method (400) of claim 2, further comprising: receiving a trigger to unsubscribe the event of a PDU session of the UE; Deleting the mapping between the event ID and the ID of the PDU session of the event being unsubscribed; If there is no mapping between the event ID and an ID of a PDU session in the first NF, removing the event ID and sending a second request to the second NF to unsubscribe from the event; The method includes:

4. 2. The method (400) of claim 1, comprising: The mapping is stored in a mapping table in the first NF.

5. 2. The method (400) of claim 1, comprising: The method, wherein the first NF is a Session Management Function (SMF) or a Unified Data Management (UDM), and the second NF is an Access and Mobility Management Function (AMF).

6. 4. The method (400) of claim 3, comprising: A method wherein the first request is a Namf_EventExposure_Subscribe request, the report is carried in a Namf_EventExposure_Notify request, and the second request is a Namf_EventExposure_UnSubscribe request.

7. 7. The method (400) of claim 6, comprising: The event ID is carried in an existing or newly defined "refId" field of the Namf_EventExposure_Subscribe request and the report.

8. A method in a second Network Function (NF) implementing a producer providing an event publishing service to a first NF implementing a consumer of said event publishing service, the method comprising: receiving a request from the first NF to subscribe to an event; if the event occurs, sending a report of the event to the first NF; notifying the third NF of subscription information of the event when the third NF acts as a new producer providing the event publishing service; Including, The method, wherein the first NF is a Session Management Function (SMF) or a first UDM, the second NF is an Access and Mobility Management Function (AMF), and the third NF is another AMF, and if the other AMF and the second UDM both support an "ESSYNC" function, the subscription information further includes an indicator indicating whether the other AMF needs to synchronize the subscription of the event with the second UDM, and the second UDM is the first UDM or another UDM.

9. 9. The method of claim 8, A first value of the indicator indicates that the other AMF does not need to synchronize the subscription to the event with the second UDM; The method, wherein a second value of the indicator indicates that the other AMF needs to synchronize the subscription to the event with the second UDM.

10. 10. The method of claim 9, If the first NF is the SMF, the subscription information includes the indicator having the first value.

11. 10. The method of claim 9, If the first NF is the first UDM, the subscription information includes the indicator having the second value.

12. 10. The method of claim 9, The method, wherein the indicator is an "eventSyncInd" information element (IE).

13. 10. The method of claim 9, The first value is "false" and the second value is "true."

14. A first Network Function (NF) (900) implementing a consumer of an event publishing service provided by a second Network Function (NF) implementing a producer of said event publishing service, A processor (901); A memory (902) storing instructions which, when executed by the processor, cause the first NF to perform the method according to any one of claims 1 to 7; The first NF is equipped with the above.

15. A second network function (NF) (1000) implementing a producer that provides an event publishing service to a first network function (NF) implementing a consumer of the event publishing service, A processor (1001), A memory (1002) storing instructions which, when executed by the processor, cause the second NF to perform the method according to any one of claims 8 to 13; The second NF is provided with:

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