Method and apparatus for the same event subscription for multiple sessions of a single UE

Abstract

To provide a method performed by a first NF implementing a consumer of an Event Exposure service provided by a second NF implementing a producer of the Event Exposure service in order to solve a problem such as an increase in a traffic load between a SMF and an AMF in a 5G network, a network function (NF) and a machine-readable medium.SOLUTION: A method includes: receiving a trigger for subscribing an event for a PDU session of a UE; allocating an event ID specific to the UE for the event, and sending a first request for subscribing the event including the event ID to the second NF, if the event has not been allocated with the event ID; and saving mapping between the event ID and the ID of the PDU session. By this method, the waste of resources for the first NF and the second NF can be reduced, for example, the message interaction and the traffic between the two NFs are reduced, and the CPU resources are saved on each of the two NFs.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The non-limiting and exemplary embodiments of the present disclosure generally relate to the technical field of mobile communication networks, and more specifically, to methods and apparatuses for the same event subscription of multiple sessions of one user equipment (UE).

Background Art

[0002] This section introduces aspects that may help deepen the understanding of the disclosure. Therefore, the description of this section should be read from this perspective and should not be understood as an approval of what is in the prior art or what is not in the prior art.

[0003] The network function (NF) of a mobile communication network can provide an event publishing service as a service producer, and enable another NF as a service consumer to subscribe to event notifications and receive notifications regarding the events. For example, the access and mobility management function (AMF) as a producer in a 5G network can provide such a service to another NF as a consumer, such as the session management function (SMF), the 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 the AMF in a 5G network as the producer of the event publishing service and another NF as the consumer of the event publishing service in the 5G network, the three basic operations are described below.

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

[0006] Figure 1 shows an example of subscription operation between an NF service consumer and AMF.

[0007] In step 1 of Figure 1, the NF service consumer (101) sends a POST request to create subscription resources within AMF (102). The payload body of the POST request contains a representation of each individual subscription resource to be created. The request may include an expiration date, suggested as a hint by the NF service consumer (101), representing the time period over which the subscription should remain active and over which the subscribed events will cease generating reports.

[0008] If successful, in step 2a of Figure 1, the request is accepted, and AMF(102) includes an HTTP location header in the response message that provides the location of the newly created resource (subscription), along with 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 subscribe, AMF(102) accepts the message and provides the successfully subscribed events in AmfEventSubscription.

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

[0010] II. Notification Operation The notification service operation is initiated by AMF to send a notification to the notification URI when a specific event included in the subscription occurs. To send the notification, AMF uses an HTTP POST method that includes, for example, the subscription ID, the event ID of the event that occurred, and the notification correlation ID provided by the NF service consumer when the event was subscribed, and uses the notification URI received when the subscription was created.

[0011] Figure 2 shows an example of notification behavior between an NF service consumer and AMF.

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

[0013] If successful, step 2a in Figure 2 will return "204 No content" from the NF service consumer (201).

[0014] In case of failure or redirection, step 2b in Figure 2 returns an appropriate HTTP status code indicating the error (e.g., "403 Forbidden"), along with appropriate additional error information.

[0015] III. Unsubscribe Operation The unsubscribe service operation is initiated by an NF service consumer to the AMF and deletes any existing subscriptions previously created by the NF service consumer in the AMF. The NF service consumer unsubscribes the subscriptions using the HTTP DELETE method, specifying the URI of each subscription resource to be deleted.

[0016] Figure 3 shows an example of notification behavior between an NF service consumer and AMF.

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

[0018] If successful, the request is accepted in step 2a of Figure 3, and 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] In case of failure or redirection, one of the HTTP status codes is returned in step 2b of Figure 3. In the case of a 4xx / 5xx response, the message body contains a ProblemDetails structure with a "cause" attribute set to one of the application errors.

[0020] In addition to providing event publishing services, as defined in 3GPP® Technical Specification (TS) 29.518, when both AMF and UDM support the “ESSYNC” function and UE-specific event subscriptions from UDM are available in the UE context, AMF may initiate synchronization of event subscriptions with UDM for a particular UE during the mobility registration procedure from Evolutionary Packet Systems (EPS) to Fifth Generation Systems (5GS).

[0021] To initiate event subscription synchronization, the AMF must include event subscription information in the notification request when sending a subscription change notification to the UDM. If a subscription change notification is not required, for example, when a UE re-registers with the same AMF after moving from an Evolutionary Packet System (EPS), the AMF may send a notification to the subscription change notification URI. In this case, the notification request will only include event subscription information and will not include the event report list.

[0022] AMF includes only active event subscriptions for a specific UE from the UDM Event Publishing Service in its event subscription information; that is, it includes only subscriptions targeting a specific UE (not a group of UEs or any UE) and each subscribed event with a reference ID (i.e., the "refId" field defined in "Table 6.2.6.2.3-1: Definition of Type AmfEvent" in TS29.518). For each active subscription, the following information is included: - URI of the subscription resource within AMF; - Subscription notification correlation ID; - A list of reference IDs, one for each event within the subscription; -Optionally, if the subscription ID changed during the mobility procedure, the URI of the old subscription resource on the source AMF.

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

[0024] According to the latest version of TS29.518, the reference ID is specially designed for event monitoring subscriptions from the UDM, but other NFs cannot be excluded from using it for internal AMF event subscriptions.

Summary of the Invention

Problems to be Solved by the Invention

[0025] In some cases, it is necessary to subscribe to events for the UE's PDU session. Therefore, a first NF operating as a consumer of the event publishing service in a mobile communication network may send a request to a second NF operating as a producer of the event publishing service to subscribe to events for the UE's PDU session. The request to subscribe to events for the 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 the technical specifications of the mobile communication network.

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

[0027] The first NF operating as a consumer sends requests to the second NF operating as a producer to subscribe to the same event for each of the multiple PDU sessions of the UE. That is, multiple requests are sent from the first NF to the second NF. When an event occurs, the second NF sends multiple reports of the same event to the first NF, which may cause waste of resources, for example.

[0028] For example, in a 5G network, an SMF managing PDU sessions may have M PDU sessions for a single UE. If the SMF wants to subscribe to the same event for 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, resulting in 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 for receiving and processing reports of the same event.

[0029] One of the purposes of this disclosure is to resolve or mitigate the above-mentioned problems. [Means for solving the problem]

[0030] According to a first aspect of this disclosure, the objective is achieved by a method in a first network function (NF) that implements a consumer of an event publishing service provided by a second network function (NF) that implements a producer of an event publishing service, the method comprising: receiving a trigger to subscribe to an event in a protocol data unit (PDU) session of a user device (UE); assigning a UE-specific event ID to the event if no event identifier (ID) has been assigned to the event; sending a first request to the second NF to subscribe to the event, including the event ID; and storing a mapping between the event ID and the ID of the PDU session.

[0031] According to a second aspect of the present disclosure, the objective is achieved by a first network function (NF) that implements a consumer of the event publishing service provided by a second network function (NF) that implements a producer of the event publishing service, the first NF comprising: a receiving unit that receives triggers for subscribing to events in a protocol data unit (PDU) session of a user device (UE); an assigning and transmitting unit that assigns a UE-specific event ID to an event if an event has not been assigned an event identifier (ID), and sends a first request to the second NF for subscribing to the event, including the event ID; and a storage unit that stores a mapping between the event ID and the ID of the PDU session.

[0032] According to a third aspect of this disclosure, the objective is achieved by a first network function (NF) that implements a consumer of an event publishing service provided by a second network function (NF) that implements a producer of an event publishing service, the first NF comprising a processor and memory storing instructions, the instructions which, when executed by the processor, cause the first NF to receive a trigger for subscribing to an event for a protocol data unit (PDU) session of a user device (UE), assign a UE-specific event ID to the event if no event identifier (ID) has been assigned to the event, send a first request to the second NF for subscribing 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 this disclosure, the objective is achieved by a machine-readable medium storing instructions that, when executed by the first NF, cause the first NF to perform the method according to the first aspect.

[0034] According to a fifth aspect of this disclosure, the objective is achieved by a method in a second network function (NF) that implements a producer providing an event publishing service to a first network function (NF) that implements a consumer of the event publishing service, the method comprising: receiving a request from the first NF to subscribe to an event, including the event ID of the event; storing the event ID; and, if an event occurs, sending an event report to the first NF, including the event ID.

[0035] According to a sixth aspect of this disclosure, the objective is achieved by a second network function (NF) that implements a producer providing an event publishing service to a first network function (NF) that implements a consumer of the event publishing service, the second NF comprising: a receiving unit that receives requests from the first NF to subscribe to an event, including the event ID of the event; a storage unit that stores the event ID; and a transmitting unit that, when an event occurs, sends an event report to the first NF, including the event ID.

[0036] According to a seventh aspect of this disclosure, the objective is achieved by a second network function (NF) that implements a producer providing an event publishing service to a first network function (NF) that implements a consumer of the event publishing service, the second NF comprising a processor and memory storing instructions, the instructions, when executed by the processor, cause the second NF to receive a request from the first NF to subscribe to an event, including the event ID of the event, store the event ID, and, if an event occurs, send an event report to the first NF, including the event ID.

[0037] According to the eighth aspect of this disclosure, the objective is achieved by a machine-readable medium storing instructions that, when executed by the second NF, cause the second NF to perform the method according to the fifth aspect.

[0038] According to a ninth aspect of the Disclosure, the Disclosure also provides a method in a second Network Function (NF) that implements a producer providing event publishing services to a first Network Function (NF) that implements a consumer of event publishing services, the method comprising: receiving a request from the first NF to subscribe to an event; sending an event report to the first NF if an event occurs; and notifying the third NF of the event subscription information if the third NF is acting as a new producer providing event publishing services, wherein the first NF is a Session Management Function (SMF) or first UDM, the second NF is an Access and Mobility Management Function (AMF), the third NF is another AMF, and if the other AMF and the second UDM both support the “ESSYNC” function, the subscription information further includes an indicator indicating whether the other AMF needs to synchronize the event subscription with the second UDM, wherein the second UDM is the first UDM or another UDM.

[0039] According to a tenth aspect of the Disclosure, the Disclosure also provides a second Network Function (NF) that implements a producer providing the event publishing service to a first Network Function (NF) that implements a consumer of the event publishing service, the second NF comprising a receiving unit that receives requests from the first NF to subscribe to events, a transmitting unit that sends event reports to the first NF when events occur, and a notification unit that notifies the third NF of event subscription information when the third NF is acting 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), the third NF is another AMF, and if the other AMF and the second UDM both support the “ESSYNC” function, the subscription information further includes an indicator indicating whether the other AMF needs to synchronize the event subscription with the second UDM, the second UDM is either the first UDM or another UDM.

[0040] According to an eleventh aspect of the Disclosure, the Disclosure also provides a second Network Function (NF) that implements a producer providing the event publishing service to a first Network Function (NF) that implements a consumer of the event publishing service, the second NF including a processor and memory storing instructions, the instructions which, when executed by the processor, cause the second NF to receive a request from the first NF to subscribe to an event, send an event report to the first NF if an event occurs, and notify the third NF of the event subscription information if the third NF is acting as a new producer providing the event publishing service, the first NF being a Session Management Function (SMF) or first UDM, the second NF being an Access and Mobility Management Function (AMF), the third NF being another AMF, and if the other AMF and the second UDM both support the “ESSYNC” function, the subscription information further includes an indicator indicating whether the other AMF needs to synchronize the event subscription with the second UDM, the second UDM being the first UDM or another UDM.

[0041] According to a twelfth aspect of this disclosure, the disclosure also provides a machine-readable medium that stores instructions causing the second NF to perform the method according to the ninth aspect when executed by the second NF.

[0042] With this invention, when it is necessary to subscribe to the same event in multiple sessions, the first NF sends only one request, and the second NF sends only one report of the event when the event occurs. Thus, the exchange of messages and traffic between the two NFs is reduced, and resource waste is reduced, such as saving CPU resources in each of the two NFs.

[0043] The above and other aspects, features, and advantages of this disclosure will become more fully apparent from the following detailed description with reference to the accompanying drawings. In the drawings, similar reference numbers or letters are used to indicate similar or equivalent elements. The drawings are provided to facilitate a better understanding of the embodiments of this disclosure and are not necessarily drawn to a specific scale. [Brief explanation of the drawing]

[0044] [Figure 1] A diagram illustrating an example of subscription operation between an NF service consumer and AMF. [Figure 2] A diagram illustrating an example of notification behavior between an NF service consumer and AMF. [Figure 3] A diagram illustrating an example of notification behavior between an NF service consumer and AMF. [Figure 4] A flowchart of the method in the first National Forum for implementing the consumer of the event publishing service as described in this disclosure. [Figure 5] A flowchart of the method in the second National Forum for implementing a producer that provides event publishing services as disclosed in this disclosure. [Figure 6] A diagram illustrating an example of processing and signaling exchange at the first and second NFs according to this disclosure. [Figure 7] A schematic block diagram of the first NF as disclosed herein. [Figure 8] A schematic block diagram of the second NF as disclosed herein. [Figure 9] Another schematic block diagram of the first NF as disclosed herein. [Figure 10] Another schematic block diagram of the second NF as disclosed herein. [Modes for carrying out the invention]

[0045] Embodiments of this disclosure will be described in more detail below with reference to the accompanying drawings. However, embodiments of this specification can be embodied in many different forms and should not be construed as limiting the scope of the appended claims.

[0046] The terms used herein are intended solely to describe specific embodiments and are not intended to limit them. The singular form is intended to include the plural form unless the context clearly indicates otherwise. When used herein, the terms “contains,” “equip,” and / or “have” identify the presence of a described feature, integer, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0047] Furthermore, the use of ordinal numbers such as "first," "second," and "third" in this specification to modify elements does not in itself indicate priority, the rank of one element relative to other elements, or the temporal order in which the actions of a method are performed, but is used solely as a label to distinguish elements, to differentiate one element with a particular name from other elements with the same name (however, because ordinal numbers are used).

[0048] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as they are commonly understood. Furthermore, terms used herein should be interpreted as having the same meaning as their meanings in the context of this specification and related technologies, and not as ideal or overly formal unless explicitly defined herein.

[0049] Figure 4 shows a flowchart of a method in the first NF that implements a consumer of the event publishing service, provided by the second NF that implements the producer of the event publishing service. Method 400 includes the steps of: receiving a trigger to subscribe to an event in the UE's PDU session; assigning a UE-specific event ID to the event if the event does not have an event ID assigned to it, sending a first request to the second NF to subscribe to the event, including the event ID; and storing a mapping between the event ID and the ID of the PDU session.

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

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

[0052] In one embodiment, the mapping is stored in the mapping table of the first NF.

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

[0054] In a further embodiment, the first request is a Namf_EventExposure_Subscribe request, the report is carried by 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 an existing "refId" field or a newly defined field within the Namf_EventExposure_Subscribe request and report.

[0056] A flowchart of Method 500 in which a producer providing an event publishing service is implemented in a first NF that implements a consumer of the event publishing service includes steps 501 of receiving a request from the first NF to subscribe to an event, including the event ID of the event; step 502 of saving the event ID; and step 503 of sending an event report, including the event ID, to the first NF if the event occurs.

[0057] In one embodiment, Method 500 further includes notifying the third NF of event subscription information, including an event ID, if the third NF is acting as a new producer providing event publishing services.

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

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

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

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

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

[0063] Both the first and second NFs can be implemented as network elements on dedicated hardware, as software instances or firmware running on hardware, as virtualization functions instantiated on an appropriate platform (such as cloud infrastructure), or as any combination thereof.

[0064] Here, as shown in Figure 6, further embodiments relating to SMF (as a consumer) and AMF (as a producer) in a 5G network are described. While the further embodiments described herein relate to SMF, AMF and 5G networks, it can be understood that the embodiments may also be applicable to other NFs and / or other mobile communication networks if the same problem exists in the mechanism for requesting subscriptions for multiple sessions of a single UE. It can also be understood that while specific terms are used in the embodiments, the embodiments are not limited to those specific terms and may apply to all similar entities. For example, "user equipment" / "UE" in this specification may refer to, for example, a user terminal, station, terminal, terminal node, etc.

[0065] Figure 6 shows an example of processing and signaling exchange in the first and second NFs according to this disclosure, where SMF(601) is an example of the first NF and AMF(602) is an example of the second NF. Note that although only two PDU sessions are used as an example in Figure 6, this does not mean that a maximum of 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 for a UE depends on 3GPP® limitations, such as (1) the maximum number of PDU sessions for a single UE as defined by 3GPP®, and (2) the number of PDU sessions for a single UE that can connect to the same SMF simultaneously.

[0066] The event will be subscribed to for the first time for the I.UE PDU session. Step 1: The SMF, a consumer of the event publishing service, receives a trigger to subscribe to events for the 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 specified by the technical specifications of the mobile communications network.

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

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

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

[0070] Step 4: The AMF can accept the first request by sending a response to the SMF, which may or may not include an event ID. In this example, the response could be a Namf_EventExposure_Subscribe response. If the present invention is applied to other mobile communication networks, such a response may not exist.

[0071] II. The same event is subscribed to in a different PDU session of 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 discovers that an event ID has been assigned to the event, meaning that the SMF has previously subscribed to the same event from the AMF for this UE. Therefore, the SMF does not need to send another request to the AMF to subscribe to the event, and can reduce signaling by simply storing the mapping between the event ID and the PDU session ID in a mapping table, for example. As mentioned above, the mapping may be stored in a data structure other than the mapping table. In any case, as is clear from Figure 6, the mapping table stores the mapping between "identifier1" and {"session_id1","session_id2"}.

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

[0074] According to this disclosure, since event IDs are unique to each UE, it can be understood that if multiple event IDs have been previously assigned to events from PDU sessions originating from multiple UEs, then multiple event IDs may exist in the report.

[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. When the present invention is applied to other mobile communication networks, such a response may not be available.

[0076] IV.SMF forwards the event report to the corresponding PDU session. Step 9: SMF uses the event ID in the report received from AMF (in this example, "identifer1") and the local mapping table to determine which PDU sessions are covered in the report. In this example, the report containing event ID "identifer1" is, according to the mapping table, for the PDU session with ID "session_id1" and the PDU session with ID "session_id2".

[0077] If a report contains multiple event IDs, SMF uses each event ID and its corresponding mapping table to determine which PDU sessions are included in the report.

[0078] Step 10: 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 "session_id2".

[0079] Compared to per-session subscriptions, AMF reports events from multiple PDU sessions in a single UE with only one report, thus saving signaling overhead. If M PDU sessions share the same event subscription, the reporting signaling overhead can be reduced by (M-1) / M.

[0080] The V.UE PDU session event will be unsubscribed. Step 11: The SMF receives a trigger to unsubscribe from events for the 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 specified by the technical specifications of the mobile communications network.

[0081] Step 12: SMF removes the mapping between the event ID (in this example, "identifier1") and the ID of the PDU session to which the event is unsubscribed (in this example, "session_id1") by, for example, removing the PDU session ID "session_id1" from the mapping table. Thus, only the mapping between event ID "identifier1" and session ID "session_id2" remains in the mapping table.

[0082] Compared to per-session subscriptions, this scenario eliminates the need to send requests to AMF to unsubscribe from events, thus reducing the signaling overhead for unsubscribing.

[0083] VI.AMF will send SMF a further report on the event. Step 13: If the event occurs again, AMF sends a further report of the event to 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 an existing "refId" field or a newly defined field in the further report.

[0084] According to this disclosure, since event IDs are unique to each UE, it can be understood that if multiple event IDs have been previously assigned to events from PDU sessions originating from multiple UEs, then multiple event IDs may exist within a further report.

[0085] Step 14: The SMF may acknowledge receipt of further reports by sending a response to the AMF. In this example, the response may be a Namf_EventExposure_Notify response. When the present invention is applied to other mobile communication networks, such a response may not be available.

[0086] VII.SMF forwards further event reports to the corresponding PDU session. Step 15: SMF uses the event ID in the further report received from AMF (in this example, "identifer1") and the local mapping table to determine which PDU sessions are subject to further reporting. In this example, the further report containing event ID "identifer1" will only target PDU sessions with ID "sesson_id2" according to the mapping table.

[0087] If a further report contains multiple event IDs, SMF uses each event ID and its corresponding mapping table to determine which PDU sessions should be included in the further report.

[0088] Step 16: SMF forwards further reports to the corresponding PDU sessions. In this example, further reports are forwarded only to the PDU session whose ID is "session_id2". The event for another PDU session in VII.UE will be unsubscribed.

[0089] Step 17: The SMF receives a trigger to unsubscribe from events 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 specified by the technical specifications of the mobile communications network.

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

[0091] Step 19: Since there are no PDU sessions that need to subscribe to the event, SMF sends a second request to AMF to unsubscribe from the event. In this example, the second request could be 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, such a response may not be present.

[0093] If a third NF were to act as a new producer providing event publishing services, it would be understood that the second NF would need to notify the third NF of event subscription information, including the event ID. For example, if a new AMF were to act as a new producer providing event publishing services, the AMF would need to notify the new AMF of event subscription information, including the event ID. The third NF (i.e., the new producer) could operate similarly to the second NF; for example, the new producer could also store the event ID and, when an event occurs, send a report to the first NF containing the event ID for that event.

[0094] However, if the first NF is an NF other than a UDM, for example, if the first NF is an SMF, and the subscription information includes an event ID in the existing "refId" field, and both the new AMF and UDM support the "ESSYNC" function, then if the new AMF determines that the "refId" field is not empty, the new AMF may initiate unnecessary synchronization of event subscriptions with the UDM for a particular UE. To avoid this unnecessary subscription synchronization, the subscription information may further include an indicator in the new AMF that indicates that event subscriptions do not need to be synchronized with the UDM. For example, a new information element (IE) "eventSyncInd" may be defined as an indicator in the "AmfEventSubscription" type as defined in 3GPP® TS29.518. A value of "true" for IE "eventSyncInd" means that event subscription synchronization with the UDM will be performed in the subscription, while the absence of IE "eventSyncInd" or a value of "false" for IE "eventSyncInd" may mean that event subscription synchronization with the UDM is not required in the subscription. Therefore, if "eventSyncInd" does not exist in IE, or if IE"eventSyncInd" has a value of "false", it can be used as an indicator to the new AMF that it does not need to synchronize event subscriptions with the UDM. Furthermore, depending on certain traffic requirements, if both the new AMF and UDM support the "ESSYNC" function and the first NF is the UDM or another UDM, the new AMF should start synchronizing event subscriptions with the UDM, in which case the indicator in the subscription information should be set to a value indicating that the new AMF should synchronize event subscriptions with the UDM (for example, the value of IE"eventSyncInd" is set to "true"). In any case, if the third NF is the new AMF, the subscription information may optionally include an indicator indicating whether the new AMF needs to synchronize event subscriptions with the UDM.

[0095] Figure 7 shows a schematic block of the first NF700 as disclosed herein. The first NF700 implements a consumer of an event publishing service provided by a second NF which implements a producer of the event publishing service. The first NF700 may include a receiving unit 701 that receives triggers to subscribe to events in a UE's PDU session; an assigning and transmitting unit 702 that assigns a UE-specific event ID to an event if the event does not have an event ID assigned to it, and sends a first request to the second NF to subscribe to the event, including the event ID; and a storage unit 703 that stores a mapping between the event ID and the ID of the PDU session.

[0096] Figure 8 shows a schematic block of the second NF800 as disclosed herein. The second NF800 implements a producer that provides event publishing services to a first NF which implements a consumer of the event publishing service. The second NF800 may include a receiving unit 801 that receives requests from the first NF to subscribe to events, including the event ID of the event; a storage unit 802 that stores the event ID; and a transmitting unit 803 that, when an event occurs, sends an event report to the first NF, including the event ID.

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

[0098] It is understood that blocks in block diagrams and / or flowcharts, and combinations of blocks in block diagrams and / or flowcharts, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, dedicated computers, and / or other programmable data processing devices to generate machines that execute the instructions via the processors of computers and / or other programmable data processing devices, creating means to realize the functions / operations specified in the block diagrams and / or flowchart blocks.

[0099] Furthermore, the solutions of this disclosure may take the form of computer programs in memory having computer-usable or computer-readable program code embedded in a medium used by or associated with an instruction execution system. In the context of this document, memory can be any medium adapted to store or transmit programs used by or associated with an instruction execution system, apparatus, or device.

[0100] Accordingly, the Disclosure also provides a first NF900, which includes a processor 901 and a memory 902, as shown in Figure 9. In the first NF900, the memory 902 stores instructions, which, when executed by the processor 901, cause the first NF900 to execute the first NF method described above in the embodiment. The Disclosure also provides a second NF1000, which includes a processor 1001 and a memory 1002, as shown in Figure 10. In the second NF1000, the memory 1002 stores instructions, which, when executed by the processor 1001, cause the second NF1000 to execute the second NF method described above in the embodiment.

[0101] The Disclosure also provides a machine-readable medium (not shown) that, when executed on the first NF, stores instructions causing the first NF to perform the first NF method described in the above embodiments. The Disclosure also provides a machine-readable medium (not shown) that, when executed on the second NF, stores instructions causing the second NF to perform the second NF method described in the above embodiments.

[0102] This specification includes many specific implementation details, but these should not be interpreted as limitations on the scope of the implementation or the claimed content, but rather as descriptions of features specific to a particular embodiment of a particular implementation. Certain features described herein 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 individually or as any suitable subcombination in multiple embodiments. Furthermore, although features are described above as acting in a particular combination, and may even be initially claimed to act in that way, one or more features from a claimed combination may, in some cases, be removed from that combination, and the claimed combination may cover subcombinations or variations of subcombinations.

[0103] As technology advances, it will be apparent to those skilled in the art that the concepts of the present invention can be implemented in a variety of ways. The embodiments described above are provided for illustrative purposes only, not to limit the disclosure, and it should be understood that modifications and variations may be made without departing from the spirit and scope of the disclosure, as will be readily apparent to those skilled in the art. Such modifications and variations will be deemed to be within the scope of the disclosure and the appended claims. The scope of protection of the disclosure is defined by the appended claims.

[0104] In fact, according to this disclosure, the inventors propose several changes to the following content of 3GPP® TS29.518, which are indicated in bold and underlined text.

[0105] 5.3.2.2.2 Creating a Subscription The subscribe service operation is initiated by an NF service consumer, such as an NEF, against the 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 single subscription. A subscription can be associated with a single UE, a group of UEs, or any UE. An NF service consumer requests the creation of a new subscription by using the HTTP POST method, specifying the URI of the subscription collection. (See Section 6.2.3.2) NF service consumers must include the following information in the HTTP message body: - The NF ID, which indicates the identifier of the network function instance in which the subscription is initiated; - A subscription target that indicates the monitored target as one of the following types: -Specific UEs 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 will be delivered; - A notification correlation ID that indicates the correlation identifier carried in event notifications generated by the subscription; - A list of events to subscribe to; - The event type for each event as defined in Section 5.3.1. NF service consumers can include the following information in the HTTP message body: - An event-specific instant report flag indicating the instant report generated in the current event state; - An event trigger that indicates how the event will be reported (one-time report or continuous report); - Maximum number of reports, which defines the maximum number of reports before an event subscription ceases to exist; - Expiration date that defines the maximum period until an event subscription ceases to exist; - A sampling rate that defines a random subset of UEs within the target UE; AMF will report only events related to the selected subset of UEs; - Event-specific periodic report flag indicating that reports are generated periodically; - A recurring period that defines the duration of regular reporting; - Applicable per-event filters that define additional options for how events are reported; - An event-specific reference ID that indicates the value of the reference ID associated with the event being monitored. If specified, the reference ID will be included in the report triggered by the event.

[0106] [Table 1]

[0107] 1. An NF service consumer creates a subscription resource within AMF by sending a POST request. The payload body of the POST request contains a representation of the individual subscription resource to be created. The request may include an expiration date, which represents the time period after which the subscription should remain active and after which the subscribed events will cease generating reports, as suggested by the NF service consumer. 2a. If successful, the request is accepted, and AMF includes an HTTP location header in the response message providing the location of the newly created resource (subscription), along with status code 201 indicating that the requested resource has been created. If an NF service consumer includes multiple events in an event subscription and some events fail to subscribe, AMF accepts the message and provides the successfully subscribed events in AmfEventSubscription. If an NF service consumer includes an immediateFlag with a value of "true" in the event subscription, AMF includes the current state of the subscribed events, if available (for example, if the subscribed event is LOCATION_REPORT, the last known location information is included). If an event with immediateFlag set to "true" is subscribed by an NF service consumer instead of a third NF, and the notification is sent directly to the third NF, i.e., if subsChangeNotifyUri is included in the event subscription, the current state of the subscribed event is not included in the response. AMF then sends a notification to the third NF that includes the current state of the subscribed event. If an NF service consumer sets the event reporting option to ONE_TIME and AMF includes the current state of the subscribed event in its response, AMF will not send any further event notifications for the event specified in the AmfCreateEventSubscription parameter. If an NF service consumer sets the event reporting option to ONE_TIME, sets the subscribed event to LOCATION_REPORT, and immediateFlag is set to false or does not exist, AMF will send an event notification after the subscription that indicates the current location of the UE. The response may include an expiration date determined by AMF, based on the operator's policy and taking into account the expiration date included in the request, after which the subscription becomes invalid. If an NF service consumer wishes to continue receiving notifications after the subscription has expired, they must create a new subscription with AMF. AMF should not set the same expiration date for many subscriptions to avoid all subscriptions expiring simultaneously and requiring subscriptions to be recreated. If no expiration date is included in the response, the NF service consumer will consider the subscription to be valid without an expiration date. If the subscription includes a sampling rate ("sampRatio") attribute, AMF will select a random subset of UEs from the target UEs according to the sampling rate and report only the events related to the selected subset of UEs. If both the AMF and the NF consumer (i.e., the UDM) support the "ESSYNC" feature and the subscription targets a specific UE, the AMF will locally include an "eventSyncInd" IE with the value "true" in the created subscription. The "eventSyncInd" IE will not be included in the event subscription sent to the NF consumer. If the new AMF supports the "ESSYNC" feature, the "eventSyncInd" IE with the value "true" will be included in the UE context during the AMF-to-AMF mobility procedure. 2b. In case of failure or redirection, one of the HTTP status codes listed in Table 6.2.3.2.3.1-3 is returned. In the case of a 4xx / 5xx response, 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 Specific UEs When both AMF and UDM support the “ESSYNC” function, AMF may initiate synchronization of event subscriptions with UDM for a specific UE during the mobility registration procedure from EPS to 5GS if UE-specific event subscriptions from UDM are available in the UE context (see Section 4.11.5.2 of 3GPP® TS23.502[3]). To initiate event subscription synchronization, AMF must include event subscription information in the notification request when sending a subscription change notification to the UDM. If a subscription change notification is not required (for example, if a UE re-registers with the same AMF after moving from EPS), AMF may send a notification to the subscription change notification URI. In this case, the notification request will only include event subscription information and will not include the event report list. AMF shall include only active event subscriptions in its event subscription information that are subject to event subscription synchronization with UDM (determined according to the definition in Section 5.3.2.2.2). For each active subscription, include the following information: - URI of the subscription resource within AMF; - Subscription notification correlation ID - A list of one reference ID for each event within the subscription -Optionally, if the subscription ID changed during the mobility procedure, the URI of the old subscription resource on the source AMF. When UDM receives event subscription information from AMF, UDM uses the reference ID and notification correlation ID to compare AMF's active event subscriptions with active UDM event publishing subscriptions and performs the following: - If an event is detected by AMF but does not exist in AMF, UDM subscribes to the event in AMF by creating a new AMF event subscription or updating an existing AMF event subscription; - If an event exists in AMF but not in UDM, UDM will unsubscribe from the event from AMF by deleting or renewing the AMF event subscription.

[0108] [Table 2] [Table 3]

[0109] 6.2.8 Function Negotiation The feature negotiation mechanism specified in section 6.6 of 3GPP® TS29.500[4] is used to negotiate (if any) optional features applicable to the Namf_EventExposure service between AMF and NF service consumers. NF service consumers must indicate to the Namf_EventExposure service if they support any optional features by including the `supportedFeatures` attribute in the payload of the HTTP request message used to create the subscription resource. AMF determines the features supported by the service operation as specified in section 6.6 of 3GPP® TS29.500[4] and indicates the supported features by including the supportedFeatures attribute in the HTTP response payload for creating the subscription resource. The syntax for the supportedFeatures attribute is defined in section 5.2.2 of 3GPP® TS29.571[6]. The following functions are defined for the Namf_EventExposure service:

[0110] [Table 4]

[0111] [Table 5]

[0112] Table 6 Table 7 Table 8

[0113] Table 9 Table 10 Table 11

Claims

1. A method (500) in which a producer providing the event publishing service is implemented in a second network function (NF) that implements a consumer of the event publishing service, Receiving a request from the first NF to subscribe to events of one or more protrol data unit (PDU) sessions of a user device, wherein the request includes the event ID of the events of the one or more PDU sessions of the user device (501), If the aforementioned event occurs, a report of the event is sent to the first NF, the report including the event ID (503), A method that includes this.

2. The method according to claim 1 (500), further, A method that includes notifying the third NF of subscription information for the event, including the event ID, when the third NF acts as a new producer providing the event publishing service.

3. A method (500) according to claim 2, wherein the first NF is a session management function (SMF) or integrated data management (UDM), and the second NF is an access and mobility management function (AMF).

4. A method (500) according to claim 3, wherein the request is a Namf_EventExposure_Subscribe request and the report is delivered by a Namf_EventExposure_Notify request.

5. A method (500) according to claim 4, wherein the event ID is carried in an existing "refId" field or a newly defined field in the Namf_EventExposure_Subscribe request and the report.

6. A method (500) according to claim 2, wherein the third NF is another AMF, and the subscription information includes the event ID in an existing "refId" field.

7. A method (500) according to claim 6, wherein if the other AMF and integrated data management (UDM) both support the “ESSYNC” function, the subscription information further includes an indicator indicating that the subscription information for the event does not need to be synchronized with the UDM.

8. A first NF implementing a consumer for the event publishing service, and a second NF (1000) implementing a producer that provides the event publishing service, Processor (1001), When executed by the aforementioned processor, the second NF has a memory (1002) that stores instructions to execute the method according to any one of claims 1 to 7, The second NF is equipped with [this feature].

9. A machine-readable storage medium that, when executed on the second NF, stores an instruction causing the second NF to execute the method according to any one of claims 1 to 7.

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