EP4627832A1

EP4627832A1 - Methods, network nodes, and media for implicit event subscription removal

Info

Publication number: EP4627832A1
Application number: EP22966758.9A
Authority: EP
Inventors: Subrata Mukherjee; David Castellanos Zamora; Jesus Angel DE GREGORIO RODRIGUEZ; Yunjie Lu; Emiliano Merino Vazquez
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2022-11-29
Filing date: 2022-11-29
Publication date: 2025-10-08
Also published as: CN120283427A; WO2024113159A1

Abstract

The present disclosure provides a first network node and a method (200) performed by the first network node. The method (200) includes: receiving (S201), from a second network node, a request message for subscribing events of a User Equipment 'UE' served by the first network node; and transmitting (S203), to the second network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node. The present disclosure further provides a corresponding second network node and a method (300) performed by the second network node.

Description

METHODS, NETWORK NODES, AND MEDIA FOR IMPLICIT EVENT SUBSCRIPTION REMOVAL

TECHNICAL FIELD

The present disclosure relates to wireless communications, and in particular, to methods, network nodes, and computer readable storage media for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last Protocol Data Unit (PDU) session of a User Equipment (UE) being released by the UE in the first network node.

BACKGROUND

This section is intended to provide a background to the various embodiments of the technology described in this disclosure. The description in this section may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and/or claims of this disclosure and is not admitted to be prior art by the mere inclusion in this section.
Application Function (AF) may subscribe to event (s) (event exposure) that are notified by Session Management Function (SMF) (e.g. PDU session status) .
Handling of the last PDU session for a given UE being deregistered in the SMF (i.e., the SMF does not serve the UE for PDU sessions) is currently being discussed. In this case, the SMF deregisters the last PDU session from the UDM (via Nudm_UEContextManagement service) , and the UDM, upon removal of ongoing event subscriptions stored for that SMF in Unified Data Repository (UDR) , needs to unsubscribe towards the SMF for the removed event (s) .
In order to ensure the removal/cleanup of event subscriptions in the SMF, the UDM sends an unsubscribe (e.g., HTTP DELETE) request to the SMF. However, the SMF might have decided previously to add the event (s) requested for the UE as a part of UE context. This would mean that when the UE context is terminated, the event (s) /resource (s) in the SMF are no longer existing in the SMF. Therefore, the HTTP DELETE request from the UDM will result in a HTTP response 404 Not Found from the SMF, which might be understood by the Mobile Network Operator (MNO) as a faulty situation, when in reality this is not a fault. Even if the SMF returns 200 OK (instead of 404 Not Found) to fix this, unnecessary signaling (involving potential failovers and/or reattempts) is unavoidable.
It is thus desired to address or alleviate at least the above issue and the like.
SUMMARY
Certain aspects of the present disclosure and their embodiments may provide solutions to the above or other issues. In particular, the embodiments of the present disclosure propose that the SMF indicates to the UDM (which has subscribed event (s) of a UE served by the SMF) that the event (s) of the UE stored as at least a part of UE context can be removed locally by the SMF upon a deregistration process of the SMF toward the UDM due to a last PDU session of the UE being released by the UE in the SMF.
According to a first aspect of the present disclosure, a method performed by a first network node is provided. The method includes: receiving, from a second network node, a request message for subscribing events of a UE served by the first network node; and transmitting, to the second network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the method further includes: removing the UE context locally in the first network node.
In an exemplary embodiment, the first indication is transmitted to the second network node in a response message for subscribing the events of the UE.
In an exemplary embodiment, the request message for subscribing the events of the UE comprises a second indication indicating that the second network node can skip a request message for unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the method further includes: determining, based on the second indication, that the subscribed events of the UE can be safely stored and removed as at least a part of UE context; and storing the subscribed events of the UE as at least a part of UE context.
In an exemplary embodiment, the first indication is transmitted to the second network node in a deregistration request message transmitted in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first network node is an SMF node, and the second network node is a UDM node.
According to a second aspect of the present disclosure, a method performed by a second network node is provided. The method includes: transmitting, to a first network node, a request message for subscribing events of a UE served by the first network node; and receiving, from the first network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the method further includes: skipping a request message for unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first indication is received from the first network node in a response message for subscribing the events of the UE.
In an exemplary embodiment, the request message for subscribing the events of the UE comprises a second indication indicating that the second network node can skip a request message for unsubscribing/deleting events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first indication is received from the first network node in a deregistration request message received in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first network node is an SMF node, and the second network node is a UDM node.
According to a third aspect of the present disclosure, a first network node is provided. The UE includes: at least one processor, and at least one memory, storing instructions which, when executed on the at least one processor, cause the first network node to perform any of the methods according to the first aspect of the present disclosure.
According to a fourth aspect of the present disclosure, a second network node is provided. The second network node includes: at least one processor, and at least one memory, storing instructions which, when executed on the at least one processor, cause the second network node to perform any of the methods according to the second aspect of the present disclosure.
According to a fifth aspect of the present disclosure, a computer readable storage medium is provided. The computer readable storage medium has computer program instructions stored thereon, the computer program instructions, when executed by at least one processor, causing the at least one processor to perform any of the methods according to any of the first to second aspects of the present disclosure.
Certain embodiments of the present disclosure may provide technical advantage (s) .
With such an indication of the SMF to the UDM that the events of the UE stored as at least a part of UE context can be removed locally by the SMF upon a deregistration process of the SMF toward the UDM due to a last PDU session of the UE being released by the UE in the SMF, it is allowed to let the UDM know about the SMF event storage and handling by means of a new feature (the indication) in either a response message for subscribing the events of the UE or a deregistration request message transmitted in the deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node. In this way, the UDM may safely determine its own handling of events and related signaling towards the SMF, e.g., skipping a request message for explicitly unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
Therefore, the embodiments of the present disclosure may avoid unnecessarily signaling between the UDM and the SMF, and also improve the network monitoring since it avoids Key Performance Indicator (KPI) degradation associated to errors in frequent and normal operations.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:
FIG. 1 schematically shows an exemplary signaling sequence diagram of a procedure for explicit event subscription removal upon a deregistration process of an SMF toward a UDM due to a last PDU session ofa UE being released by the UE in the SMF;
FIG. 2 schematically shows a method performed by a first network node for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last PDU session of a UE being released by the UE in the first network node according to an exemplary embodiment of the present disclosure;
FIG. 3 schematically shows a method performed by a second network node for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last PDU session of a UE being released by the UE in the first network node according to an exemplary embodiment of the present disclosure;
FIG. 4 schematically shows an exemplary signaling sequence diagram of a procedure for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last PDU session of a UE being released by the UE in the first network node, in which the methods performed by the first network node and the second network node according to the exemplary embodiments of the present disclosure are applied;
FIG. 5 schematically shows another exemplary signaling sequence diagram of a procedure for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last PDU session of a UE being released by the UE in the first network node, in which the methods performed by the first network node and the second network node according to the exemplary embodiments of the present disclosure are applied;
FIG. 6 schematically shows a structural block diagram of a first network node according to an exemplary embodiment of the present disclosure;
FIG. 7 schematically shows a structural block diagram of a first network node according to another exemplary embodiment of the present disclosure;
FIG. 8 schematically shows a structural block diagram of a second network node according to an exemplary embodiment of the present disclosure; and
FIG. 9 schematically shows a structural block diagram of a second network node according to another exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, the principle and spirit of the present disclosure will be described with reference to illustrative embodiments. Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art. Additional information may make reference to the following documents, which are incorporated herein in their entirety by reference:
3GPP TS 29.522 V17.5.0, “3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; 5G System; Network Exposure Function Northbound APIs; Stage 3 (Release 17) , ” 2022-03;
3GPP TS 29.122 V17.5.0, “3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; T8 reference point for Northbound APIs; (Release 17) , ” 2022-03; and
3GPP TS 29.503 V17.7.0, “3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; 5G System; Unified Data Management Services; Stage 3 (Release 17) , ” 2022-06.
Those skilled in the art will appreciate that the term “exemplary” is used herein to mean “illustrative, ” or “serving as an example, ” and is not intended to imply that a particular embodiment is preferred over another or that a particular feature is essential. Likewise, the terms “first” and “second, ” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises, ” “comprising, ” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.
In some embodiments described herein, the term “coupled, ” “connected, ” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections.
The term “network node” used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS) , radio base station, base transceiver station (BTS) , base station controller (BSC) , radio network controller (RNC) , g Node B (gNB) , evolved Node B (eNB or eNodeB) , Node B, multi-standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE) , integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP) , transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH) , a core network node (e.g., mobile management entity (MME) , self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc. ) , an external node (e.g., 3rd party node, a node external to the current network) , nodes in distributed antenna system (DAS) , a spectrum access system (SAS) node, an element management system (EMS) , etc. The network node may also comprise test equipment. The term “radio node” used herein may be used to also denote a wireless device such as a wireless device or a radio network node.
In some embodiments, the non-limiting terms wireless device or UE are used interchangeably. The UE herein can be any type of wireless device capable of communicating with a network node or another wireless device over radio signals, such as wireless device. The UE may also be a radio communication device, target device, D2D wireless device, machine type wireless device or wireless device capable of machine to machine communication (M2M) , low-cost and/or low-complexity wireless device, a sensor equipped with wireless device, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE) , laptop mounted equipment (LME) , USB dongles, Customer Premises Equipment (CPE) , an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device, etc.
Also, in some embodiments the generic term “radio network node” is used. It can be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB) , Node B, gNB, Multi-cell/multicast Coordination Entity (MCE) , IAB node, relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH) .
The term “radio access technology” , or RAT, may refer to any RAT e.g. Universal Terrestrial Radio Access (UTRA) , Evolved-UTRA (E-UTRA) , Narrow Band Internet Of Things (NB-IoT) , Wireless Fidelity (WiFi) , Bluetooth, next generation RAT, New Radio (NR) , 4G, 5G, etc. Any of the equipment denoted by the term node, network node or radio network node may be capable of supporting a single or multiple RATs.
The term signal or radio signal used herein can be any physical signal or physical channel. Examples of DL physical signals are reference signal (RS) such as Primary Synchronization Signal (PSS) , Secondary Synchronization Signal (SSS) , CSI-RS, Demodulation Reference Signal (DMRS) in Synchronization Signal (SS) /Physical Broadcast Channel (PBCH) block (SSB) , Discovery Reference Signal (DRS) , Cell Reference Signal (CRS) , Position Reference Signal (PRS) etc. RS may be periodic e.g. RS occasion carrying one or more RSs may occur with certain periodicity e.g. 20 ms, 40 ms etc. The RS may also be aperiodic. Each SSB carries NR-PSS, NR-SSS and NR-PBCH in 4 successive symbols. One or multiple SSBs are transmit in one SSB burst which is repeated with certain periodicity e.g. 5 ms, 10 ms, 20 ms, 40 ms, 80 ms and 160 ms. The UE is configured with information about SSB on cells of certain carrier frequency by one or more SS/PBCH block measurement timing configuration (SMTC) configurations. The SMTC configuration comprising parameters such as SMTC periodicity, SMTC occasion length in time or duration, SMTC time offset wrt reference time (e.g. serving cell’s System Frame Number (SFN) ) etc. Therefore, SMTC occasion may also occur with certain periodicity e.g. 5 ms, 10 ms, 20 ms, 40 ms, 80 ms and 160 ms. Examples of UL physical signals are reference signal such as SRS, DMRS etc. The term physical channel refers to any channel carrying higher layer information e.g. data, control etc. Examples of physical channels are PBCH, Narrowband PBCH (NPBCH) , PDCCH, PDSCH, short PUCCH (sPUCCH) , sPDSCH, sPUCCH, sPUSCH, Machine Type Communication (MTC) PDCCH (MPDCCH) , NPDCCH, NPDSCH, E-PDCCH, PUSCH, PUCCH, NPUSCH etc.
Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and/or New Radio (NR) , may be used in this disclosure, this should not be seen as limiting the scope of the present disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA) , Worldwide Interoperability for Microwave Access (WiMax) , Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM) , may also benefit from exploiting the ideas covered within this disclosure.
Note further, that functions described herein as being performed by a UE or a network node may be distributed over a plurality of UEs and/or network nodes. In other words, it is contemplated that the functions of the network node and UE described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
As previously described, in order to ensure the removal/cleanup of event subscriptions in the SMF, the UDM sends, to the SMF, an unsubscribe (e.g., HTTP DELETE) request, i.e., an explicit event subscription removal request. However, the SMF might have decided previously to add the event (s) requested for the UE as a part of UE context. This would mean that when the UE context is terminated, the event (s) /resource (s) in the SMF are no longer existing in the SMF. Therefore, the HTTP DELETE request from the UDM will result in a HTTP response 404 Not Found from the SMF, which might be understood by the Mobile Network Operator (MNO) as a faulty situation, when in reality this is not a fault. Even if the SMF returns 200 OK (instead of 404 Not Found) to fix this, unnecessarily signaling (involving potential failovers and/or reattempts) is unavoidable.
The above related issue may be clearly seen from FIG. 1, which schematically shows an exemplary signaling sequence diagram of the procedure for explicit event subscription removal upon the deregistration process of the SMF toward the UDM due to the last PDU session of the UE being released by the UE in the SMF.
Hereinafter, how the issue occurs in the current procedure for explicit event subscription removal will be described in detail in conjunction with FIG. 1. For the sake of simplicity, the description of unnecessary signaling is omitted herein.
In S1_1, the AF subscribes to an event detected and reported by the SMF (e.g. PDU session status) , and there is a serving SMF registered for the UE (i.e. UE has PDU session (s) established in the serving SMF) .
In S1_2, the UDM subscribes to the serving SMF via a request message for subscribing event (s) of the UE served by the serving SMF, e.g., an Nsmf_EventExposure_Subscribe request, which includes e.g., UE ID, MonitoringType=PDU_SESSION_STATUS etc.
In S1_3, the SMF decides to store the requested event (s) as a part of UE context (new resource ID) .
In S1_4, the SMF transmits, to the UDM, a response message, e.g., a Nsmf_EventExposure_Subscribe response, in response to the request message transmitted in S1_2, which includes e.g., success, resource ID (s) created in the SMF, etc.
In S1_5, the UDM stores the resource ID (s) allocated in the SMF in the UDR.
In S1_6, the last PDU session is released by the UE in the SMF, and the SMF triggers a deregistration process toward the UDM.
In S1_7, the SMF transmits, to the UDM, a deregistration request message transmitted in the deregistration process of the SMF toward the UDM due to the last PDU session of the UE being released by the UE in the SMF, e.g., Nudm_uecm_deregistration_request, which includes e.g., UE ID, Session ID, etc.
In S1_8, the UDM transmits, to the SMF, a corresponding deregistration response message.
In S1_9-1, since the UE context is removed in the SMF that has stored the event (s) as a part of the UE context, all resource ID (s) associated to the UE context are removed.
On the other hand, in S1_9-2, since the SMF is no longer serving the UE, the UDM decides to remove all resource ID (s) allocated in the SMF in the UDR; thus the UDM unsubscribes the event (s) in order to ensure that the resource (s) is/are also cleaned up in the SMF.
Thus, in S1_10, the UDM transmits, to the SMF, a request message for unsubscribing/deleting the subscribed event (s) of the UE, e.g., a Nsmf_EventExposure_Unsubscribe request, which includes e.g., UE ID, resource ID (s) , MonitoringType=PDU_SESSION_STATUS.
However, in S1_11, the SMF does not find the resource ID (s) since the resource ID (s) was/were removed at UE context removal.
As a result, in S1_12, the SMF transmits, to the UDM, a corresponding response message for unsubscribing/deleting the subscribed event (s) of the UE, e.g., a Nsmf_EventExposure_Unsubscribe response, which includes e.g., ERROR: 404 Not Found.
Such a response with “404 Not Found” might be understood by the MNO as a faulty situation, when in reality this is not a fault. Even if the SMF returns 200 OK (instead of 404 Not Found) to fix this, unnecessarily signaling (involving potential failovers and/or reattempts) is unavoidable. As such, the network KPIs are polluted with lots of errors associated to normal and frequent traffic situations, and on the other hand, unnecessary signaling (involving potential failovers and/or reattempts) is unavoidable.
In order to address or alleviate at least the above issue as exemplarily shown in FIG. 1, the embodiments of the present disclosure propose that the SMF indicate to the UDM (which has subscribed event (s) of a UE served by the SMF) that the event (s) of the UE subscribed by the UDM and stored as at least a part of UE context can be removed locally by the SMF upon a deregistration process of the SMF toward the UDM due to a last PDU session of the UE being released by the UE in the SMF.
The basic idea of the present disclosure consists in that
1) the SMF transmits, to the UDM that has subscribed event (s) of a UE served by the SMF, an indication indicating that the event (s) of the UE stored as at least a part of UE context can be removed locally by the SMF upon a deregistration process of the SMF toward the UDM due to a last PDU session of the UE being released by the UE in the SMF;
alternatively or additionally, the SMF may include a new feature in a response message for subscribing the event (s) of the UE, e.g., including a new Information Element (IE) IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL_LAST_SMF_REGISTRATION in Nsmf_EventExposure_Subscribe response, to let the UDM know that the event (s) of the UE stored as at least a part of UE context can be removed locally by the SMF upon the deregistration process of the SMF toward the UDM due to the last PDU session of the UE being released by the UE in the SMF, so that, when the UE context is terminated, the UDM may skip the explicit unsubscribe/deletion of the event (s) at the SMF;
as an alternative, the SMF may include a new indication in a deregistration request message, e.g., including a new IE IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL in Nudm_UECM_deregistration_request, transmitted in the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF, to inform the UDM that the event (s) are implicitly removed since they were stored as a part of the UE context; this makes the UDM aware of it so that the UDM may skip the explicit unsubscribe/deletion of the event (s) at the SMF; and
2) upon receiving such an indication, the UDM is aware about the SMF handling of the event (s) and their relationship with the UE context at the SMF instance, and thus determines that, upon removal of the event (s) in the UDR, there is no need to explicitly unsubscribe towards the SMF, since the cleanup at the SMF has been implicitly done; as such, the UDM skips the request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF;
alternatively or additionally, when subscribing to the serving SMF, the UDM may include a new feature in the request message for subscribing the event (s) of the UE, e.g., including a new IE IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL_LAST_SMF_REGISTRATION in Nsmf_EventExposure_Subscribe request, to let the SMF know that the event (s) of the UE can be safely stored as a part of UE context so that, when the UE context is terminated, the UDM may skip the request message for unsubscribing/deleting the subscribed event (s) of the UE.
Hereinafter, a method 200 performed by a first network node for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last PDU session of a UE being released by the UE in the first network node according to an exemplary embodiment of the present disclosure will be described with reference to FIG. 2.
In an exemplary embodiment, the first network node may be an SMF. It should be understood that the first network node may also be any other appropriate entity that can be configured to perform the method 200 as described below, including a virtualized entity that may be implemented on cloud. Correspondingly, the second network node may be a UDM.
As shown in FIG. 2, the method 200 may include at least steps S201 and S203.
In step S201, the first network node may receive, from the second network node, a request message for subscribing event (s) of a UE served by the first network node.
Alternatively or additionally, in an exemplary embodiment, the request message for subscribing the event (s) of the UE may include an indication indicating that the second network node can skip a request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
For example, the request message for subscribing the event (s) of the UE may be Nsmf_EventExposure_Subscribe request, and a new IE e.g., IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL_LAST_SMF_REGISTRATION may be included in the Nsmf_EventExposure_Subscribe request to indicate to the first network node that the second network node can skip a request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
That is, the first network node may be informed that the subscribed event (s) of the UE may be safely stored as a part of UE context, and that the second network node has such a capability that when the UE context is terminated, it can skip the request message for unsubscribing/deleting the subscribed event (s) of the UE.
As such, the first network node may determine, based on the indication from the second network node, that the subscribed event (s) of the UE can be safely stored and removed as at least a part of UE context; and then store the subscribed event (s) of the UE as at least a part of UE context.
It may be understood that such an indication in the request message for subscribing the event (s) of the UE may be optional.
Then in step S203, the first network node may transmit, to the second network node, an indication indicating that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the first network node upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the indication may be transmitted to the second network node in a response message for subscribing the event (s) of the UE. For example, the response message for subscribing the event (s) of the UE may be Nsmf_EventExposure_Subscribe response, and a new IE e.g., IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL_LAST_SMF_REGISTRATION may be included in the Nsmf_EventExposure_Subscribe response to indicate the second network node that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the first network node upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
Alternatively, in another exemplary embodiment, the indication may be transmitted to the second network node in the deregistration request message transmitted in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node. For example, the deregistration request message may be Nudm_UECM_deregistration_request, and a new IE e.g., IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL may be included in the Nudm_UECM_deregistration_request to indicate the second network node that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the first network node upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
Accordingly, the first network node may remove the UE context locally. On the other hand, since the second network node is informed that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the first network node upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node, it can skip an explicit request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process.
As such, unnecessarily signaling between the network nodes may be avoided, and the network monitoring may be improved since it avoids KPI degradation associated to errors in frequent and normal operations.
Hereinafter, a method 300 performed by a second network node for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last PDU session of a UE being released by the UE in the first network node according to an exemplary embodiment of the present disclosure will be described with reference to FIG. 3. It should be understood that the method 300 at the second network node corresponds to the method 200 at the first network node as previously described. Thus, some description of the method 300 may refer to that of method 200, and thus will be omitted for simplicity.
In an exemplary embodiment, the second network node may be a UDM. It should be understood that the second network node may also be any other appropriate entity that can be configured to perform the method 300 as described below, including a virtualized entity that may be implemented on cloud. Correspondingly, the first network node may be an SMF.
As shown in FIG. 3, the method 300 may include at least steps S301 and S303.
In step S301, the second network node may transmit, to the first network node, a request message for subscribing event (s) of a UE served by the first network node.
Alternatively or additionally, in an exemplary embodiment, the request message for subscribing the event (s) of the UE may include an indication indicating that the second network node can skip a request message for unsubscribing/deleting the subscribed event (s) of the UE upon a deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
For example, the request message for subscribing the event (s) of the UE may be Nsmf_EventExposure_Subscribe request, and a new IE e.g., IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL_LAST_SMF_REGISTRATION may be included in the Nsmf_EventExposure_Subscribe request to indicate to the first network node that the second network node can skip a request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
That is, the second network node may inform the first network node that the first network node may safely store the subscribed event (s) of the UE as a part of UE context, and that the second network node has such a capability that when the UE context is terminated, it can skip the request message for unsubscribing/deleting the subscribed event (s) of the UE.
It may be understood that such an indication in the request message for subscribing the event (s) of the UE may not be necessary.
Then in step S303, the second network node may receive, from the first network node, an indication indicating that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the first network node upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the indication may be received from the first network node in a response message for subscribing the event (s) of the UE. For example, the response message for subscribing the event (s) of the UE may be Nsmf_EventExposure_Subscribe response, and a new IE e.g., IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL_LAST_SMF_REGISTRATION may be included in the Nsmf_EventExposure_Subscribe response to indicate the second network node that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the first network node upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
Alternatively, in another exemplary embodiment, the indication may be received from the first network node in the deregistration request message transmitted in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node. For example, the deregistration request message may be Nudm_UECM_deregistration_request, and a new IE e.g., IMPLICIT _EVENT_SUBSCRIPTION_REMOVAL may be included in the Nudm_UECM_deregistration_request to indicate the second network node that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the first network node upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
Since the second network node is informed by the first network node that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the first network node upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node, the second network node can skip an explicit request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process.
As such, unnecessarily signaling between the network nodes may be avoided, and the network monitoring may be improved since it avoids KPI degradation associated to errors in frequent and normal operations.
FIG. 4 schematically shows an exemplary signaling sequence diagram of a procedure for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last PDU session of a UE being released by the UE in the first network node, in which the methods performed by the first network node and the second network node according to the exemplary embodiments of the present disclosure are applied. Some description of the exemplary signaling sequence diagram as shown in FIG. 4 may refer to that of methods 200 and 300 as previously described, and thus will be omitted here for simplicity.
In the following description on the exemplary signaling sequence diagram of FIG. 4, SMF is taken as an example of the first network node as previously described, and UDM is taken as an example of the second network node as previously described.
It should be noted that the description below mainly focuses on signaling related to the methods 200 and 300, and some other signaling is not described in detail to avoid obscuring the principle of the present disclosure. In FIG. 4, modification on the signaling related to the methods 200 and 300 is shown in Bold Italics, in which e.g., Signaling S4_3, S4_9-2, and optionally, S4_2 are involved.
In S4_1: the AF subscribes to an event detected and reported by the SMF (e.g. PDU session status) , and there is a serving SMF registered for the UE (i.e. UE has PDU session (s) established in the serving SMF) .
In S4_2, the UDM subscribes to the serving SMF via a request message for subscribing event (s) of the UE served by the serving SMF, e.g., an Nsmf_EventExposure_Subscribe request, which includes e.g., UE ID, MonitoringType=PDU_SESSION_STATUS etc. It may be understood that S4_2 is corresponding to S201 in FIG. 2 and S301 in FIG. 3, respectively.
As an alternative, the request message for subscribing event (s) of the UE served by the serving SMF may further include an indication indicating that the UDM is capable of skipping a request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF. For example, the Nsmf_EventExposure_Subscribe request may include a new IE, e.g., IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL_LAST_SMF_REGISTRATION. In this case, the UDM may indicate to the SMF that the UDM is capable of skipping a request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF.
Then in S4_3, the SMF may determine, based on the indication received from the UDM, that the subscribed event (s) of the UE can be safely stored and removed as at least a part of UE context; and then store the subscribed event (s) of the UE as at least a part of UE context decides to store the requested event (s) as a part of UE context (new resource ID) .
It may be understood that S4_3 is performed only if the UDM indicates to the SMF that it is capable of skipping a request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF.
In a case where the SMF receives, in S4_2, the request message for subscribing event (s) of the UE served by the serving SMF without such an indication of the UDM, i.e., the same as in S1_2 of FIG. 1, the SMF may decide to store the requested event (s) as a part of UE context (new resource ID) , i.e., the same as in S1_3 of FIG. 1.
In S4_4, the SMF transmits, to the UDM, a corresponding response message for subscribing the event (s) of the UE, e.g., a Nsmf_EventExposure_Subscribe response, in response to the request message transmitted in S4_2. In addition to general IEs, such as success, resource ID (s) created in the SMF, etc., the response message may include an indication indicating that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the SMF upon the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF. For example, the indication may be a new IE in the response message, e.g., IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL_LAST_SMF_REGISTRATION.
It may be understood that S4_4 is corresponding to S203 in FIG. 2 and S303 in FIG. 3, respectively.
In S4_5, the UDM stores the resource ID (s) allocated in the SMF in the UDR.
In S4_6, the last PDU session is released by the UE in the SMF, and the SMF triggers a deregistration process toward the UDM.
In S4_7, the SMF transmits, to the UDM, a deregistration request message transmitted in the deregistration process of the SMF toward the UDM due to the last PDU session of the UE being released by the UE in the SMF, e.g., Nudm_UECM_deregistration_request, which includes e.g., UE ID, Session ID, etc.
In S4_8, the UDM transmits, to the SMF, a corresponding deregistration response message.
In S4_9-1, since the UE context is removed in the SMF that has stored the event (s) as a part of the UE context, all resource ID (s) associated to the UE context are removed.
On the other hand, in S4_9-2, since the UDM has been informed that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the SMF upon the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF, it skips an explicit request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process.
As such, unnecessarily signaling between the network nodes, e.g., SMF and UDM, may be avoided, and the network monitoring may be improved since it avoids KPI degradation associated to errors in frequent and normal operations.
FIG. 5 schematically shows another exemplary signaling sequence diagram of a procedure for implicit event subscription removal upon a deregistration process of a first network node toward a second network node due to a last PDU session of a UE being released by the UE in the first network node, in which the methods performed by the first network node and the second network node according to the exemplary embodiments of the present disclosure are applied. Some description of the exemplary signaling sequence diagram as shown in FIG. 4 may refer to that of methods 200 and 300 as previously described, and thus will be omitted here for simplicity.
In the following description on the exemplary signaling sequence diagram of FIG. 5, SMF is taken as an example of the first network node as previously described, and UDM is taken as an example of the second network node as previously described.
It should be noted that the description below mainly focuses on signaling related to the methods 200 and 300, and some other signaling is not described in detail to avoid obscuring the principle of the present disclosure. In FIG. 5, modification on the signaling related to the methods 200 and 300 is shown in Bold Italics, in which e.g., Signaling S5_7 and S5_9-2 are involved.
In S5_1: the AF subscribes to an event detected and reported by the SMF (e.g. PDU session status) , and there is a serving SMF registered for the UE (i.e. UE has PDU session (s) established in the serving SMF) .
In S5_2, the UDM subscribes to the serving SMF via a request message for subscribing event (s) of the UE served by the serving SMF, e.g., an Nsmf_EventExposure_Subscribe request, which includes e.g., UE ID, MonitoringType=PDU_SESSION_STATUS etc. It may be understood that S5_2 is corresponding to S201 in FIG. 2 and S301 in FIG. 3, respectively.
In S5_3, the SMF decides to store the requested event (s) as a part of UE context (new resource ID) , i.e., the same as in S1_3 of FIG. 1.
In S5_4, the SMF transmits, to the UDM, a response message, e.g., a Nsmf_EventExposure_Subscribe response, in response to the request message transmitted in S1_2, which includes e.g., success, resource ID (s) created in the SMF, etc.
In S5_5, the UDM stores the resource ID (s) allocated in the SMF in the UDR.
In S5_6, the last PDU session is released by the UE in the SMF, and the SMF triggers a deregistration process toward the UDM.
In S5_7, the SMF transmits, to the UDM, a deregistration request message transmitted in the deregistration process of the SMF toward the UDM due to the last PDU session of the UE being released by the UE in the SMF, e.g., Nudm_UECM_deregistration_request. In addition to general IEs, such as UE ID, Session ID, etc., the deregistration request message may include an indication indicating that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the SMF upon the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF. For example, the indication may be a new IE in the response message, e.g., IMPLICIT_EVENT_SUBSCRIPTION_REMOVAL.
It may be understood that S5_7 is corresponding to S203 in FIG. 2 and S303 in FIG. 3, respectively.
In S5_8, the UDM transmits, to the SMF, a corresponding deregistration response message.
In S5_9-1, since the UE context is removed in the SMF that has stored the event (s) as a part of the UE context, all resource ID (s) associated to the UE context are removed.
On the other hand, in S5_9-2, since the UDM has been informed that the subscribed event (s) of the UE stored as at least a part of UE context can be removed locally by the SMF upon the deregistration process of the SMF toward the UDM due to the last session of the UE being released by the UE in the SMF, it skips an explicit request message for unsubscribing/deleting the subscribed event (s) of the UE upon the deregistration process.
As such, unnecessarily signaling between the network nodes, e.g., SMF and UDM, may be avoided, and the network monitoring may be improved since it avoids KPI degradation associated to errors in frequent and normal operations.
Hereinafter, a structure of a first network node according to an exemplary embodiment of the present disclosure will be described with reference to FIG. 6. FIG. 6 schematically shows a block diagram of the first network node 600 according to an exemplary embodiment of the present disclosure. The first network node 600 in FIG. 6 may perform the method 200 with reference to FIG. 2. Accordingly, some detailed description on the first network node 600 may refer to the corresponding description of the method 200 in FIG. 2 as well as the signaling sequence diagrams of FIGS. 4 and 5, and thus will be omitted here for simplicity.
As shown in FIG. 6, the first network node 600 may include at least a receiving unit 601 and a transmitting unit 603.
In an exemplary embodiment, the receiving unit 601 may be configured to receive, from a second network node, a request message for subscribing events of a UE served by the first network node.
Then, the transmitting unit 603 may be configured to transmit, to the second network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first network node 600 may further include a removal unit (not shown) , which may be configured to remove the UE context locally in the first network node.
In an exemplary embodiment, the first indication may be transmitted to the second network node in a response message for subscribing the events of the UE.
In an exemplary embodiment, the request message for subscribing the events of the UE may include a second indication indicating that the second network node can skip a request message for unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first network node 600 may further include a determination unit (not shown) , which may be configured to determine, based on the second indication, that the subscribed events of the UE can be safely stored and removed as at least a part of UE context; and storing the subscribed events of the UE as at least a part of UE context.
In an exemplary embodiment, the first indication may be transmitted to the second network node in a deregistration request message transmitted in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first network node may be an SMF node, and the second network node may be a UDM node.
Hereinafter, a structure of a first network node according to another exemplary embodiment of the present disclosure will be described with reference to FIG. 7. FIG. 7 schematically shows a block diagram of a first network node 700 according to an exemplary embodiment of the present disclosure. The first network node 700 in FIG. 7 may perform the method 200 as described previously with reference to FIG 2. Accordingly, some detailed description on the first network node 700 may refer to the corresponding description of the method 200 in FIG. 2 as well as the signaling sequence diagrams of FIGS. 4 and 5, and thus will be omitted here for simplicity.
As shown in FIG. 7, the first network node 700 includes at least one processor 701 and at least one memory 703. The at least one processor 701 includes e.g., any suitable CPU (Central Processing Unit) , microcontroller, DSP (Digital Signal Processor) , etc., capable of executing computer program instructions. The at least one memory 703 may be any combination of a RAM (Random Access Memory) and a ROM (Read Only Memory) . The at least one memory 703 may also include persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, or solid state memory or even remotely mounted memory.
The at least one memory 703 stores instructions executable by the at least one processor 701. The instructions, when loaded from the at least one memory 703 and executed on the at least one processor 701, may cause the first network node 700 to perform the actions, e.g., of the procedures as described earlier in conjunction with FIG. 2.
In an exemplary embodiment, the instructions, when loaded from the at least one memory 703 and executed on the at least one processor 701, may cause the first network node 700 to receive, from a second network node, a request message for subscribing events of a UE served by the first network node; and transmit, to the second network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the instructions, when loaded from the at least one memory 703 and executed on the at least one processor 701, may cause the first network node 700 to remove the UE context locally in the first network node.
In an exemplary embodiment, the first indication may be transmitted to the second network node in a response message for subscribing the events of the UE.
In an exemplary embodiment, the request message for subscribing the events of the UE may include a second indication indicating that the second network node can skip a request message for unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the instructions, when loaded from the at least one memory 703 and executed on the at least one processor 701, may cause the first network node 700 to determine, based on the second indication, that the subscribed events of the UE can be safely stored and removed as at least a part of UE context; and storing the subscribed events of the UE as at least a part of UE context.
In an exemplary embodiment, the first indication may be transmitted to the second network node in a deregistration request message transmitted in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first network node may be an SMF node, and the second network node may be a UDM node.
Hereinafter, a structure of a second network node according to an exemplary embodiment of the present disclosure will be described with reference to FIG. 8. FIG. 8 schematically shows a block diagram of the second network node 800 according to an exemplary embodiment of the present disclosure. The second network node 800 in FIG. 8 may perform the method 300 as described previously with reference to FIG. 3. Accordingly, some detailed description on the second network node 800 may refer to the corresponding description of the method 300 in FIG. 3 as well as the signaling sequence diagrams of FIGS. 4 and 5, and thus will be omitted here for simplicity.
As shown in FIG. 8, the second network node 800 may include at least a transmitting unit 801 and a receiving unit 803.
In an exemplary embodiment, the transmitting unit 801 may be configured to transmit, to a first network node, a request message for subscribing events of a UE served by the first network node.
Accordingly, the receiving unit 803 may be configured to receive, from the first network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the second network node 800 may further include a skipping unit (not shown) , which may be configured to skip a request message for unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first indication may be received from the first network node in a response message for subscribing the events of the UE.
In an exemplary embodiment, the request message for subscribing the events of the UE may include a second indication indicating that the second network node can skip a request message for unsubscribing/deleting events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first indication may be received from the first network node in a deregistration request message received in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first network node may be an SMF node, and the second network node may be a UDM node.
Hereinafter, a structure of a second network node according to another exemplary embodiment of the present disclosure will be described with reference to FIG. 9. FIG. 9 schematically shows a block diagram of a second network node 900 according to an exemplary embodiment of the present disclosure. The second network node 900 in FIG. 9 may perform the method 300 as described previously with reference to FIG. 3. Accordingly, some detailed description on the second network node 900 may refer to the corresponding description of the method 300 in FIG. 3 as well as the signaling sequence diagrams of FIGS. 4 and 5, and thus will be omitted here for simplicity.
As shown in FIG. 9, the second network node 900 includes at least one processor 901 and at least one memory 903. The at least one processor 901 includes e.g., any suitable CPU (Central Processing Unit) , microcontroller, DSP (Digital Signal Processor) , etc., capable of executing computer program instructions. The at least one memory 903 may be any combination of a RAM (Random Access Memory) and a ROM (Read Only Memory) . The at least one memory 903 may also include persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, or solid state memory or even remotely mounted memory.
The at least one memory 903 stores instructions executable by the at least one processor 901. The instructions, when loaded from the at least one memory 903 and executed on the at least one processor 901, may cause the second network node 900 to perform the actions, e.g., of the procedures as described earlier respectively in conjunction with FIG. 3.
In an exemplary embodiment, the instructions, when loaded from the at least one memory 903 and executed on the at least one processor 901, may cause the second network node 900 to transmit, to a first network node, a request message for subscribing events of a UE served by the first network node; and receive, from the first network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the instructions, when loaded from the at least one memory 903 and executed on the at least one processor 901, may cause the second network node 900 to skip a request message for unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first indication may be received from the first network node in a response message for subscribing the events of the UE.
In an exemplary embodiment, the request message for subscribing the events of the UE may include a second indication indicating that the second network node can skip a request message for unsubscribing/deleting events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first indication may be received from the first network node in a deregistration request message received in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
In an exemplary embodiment, the first network node may be an SMF node, and the second network node may be a UDM node.
The present disclosure also provides at least one computer program product in the form of a non-volatile or volatile memory, e.g., a non-transitory computer readable storage medium, an Electrically Erasable Programmable Read-Only Memory (EEPROM) , a flash memory and a hard drive. The computer program product includes a computer program.
The computer program includes: code/computer readable instructions, which when executed by the at least one processor 701 causes the first network node 700 to perform the actions, e.g., of the procedures described earlier in conjunction with FIG. 2; or code/computer readable instructions, which when executed by the at least one processor 901 causes the second network node 900 to perform the actions, e.g., of the procedures described earlier respectively in conjunction with FIG. 3.
The computer program product may be configured as a computer program code structured in computer program modules. The computer program modules could essentially perform the actions of the flow illustrated in any of FIGS. 4 to 5.
The processor may be a single CPU (Central processing unit) , but could also include two or more processing units. For example, the processor may include general purpose microprocessors; instruction set processors and/or related chips sets and/or special purpose microprocessors such as Application Specific Integrated Circuit (ASICs) . The processor may also include board memory for caching purposes. The computer program may be carried by a computer program product connected to the processor. The computer program product may include a non-transitory computer readable storage medium on which the computer program is stored. For example, the computer program product may be a flash memory, a Random-access memory (RAM) , a Read-Only Memory (ROM) , or an EEPROM, and the computer program modules described above could in alternative embodiments be distributed on different computer program products in the form of memories.
Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may include computing devices with different combinations of components. It is to be understood that these computing devices may include any suitable combination of hardware and/or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may include multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and/or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.
In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and/or by end users and a wireless network generally.
Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.
It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings.

Claims

A method (200) performed by a first network node, comprising:

receiving (S201) , from a second network node, a request message for subscribing events of a User Equipment ‘UE’ served by the first network node; and

transmitting (S203) , to the second network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.

,
The method (200) of claim 1, further comprising:

removing the UE context locally in the first network node.
The method (200) of claim 1 or 2, wherein the first indication is transmitted to the second network node in a response message for subscribing the events of the UE.
The method (200) of any of claims 1 to 3, wherein the request message for subscribing the events of the UE comprises a second indication indicating that the second network node can skip a request message for unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
The method (200) of claim 4, further comprising:

determining, based on the second indication, that the subscribed events of the UE can be safely stored and removed as at least a part of UE context; and

storing the subscribed events of the UE as at least a part of UE context.
The method (200) of claim 1 or 2, wherein the first indication is transmitted to the second network node in a deregistration request message transmitted in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
The method (200) of any of claims 1 to 6, wherein

the first network node is a Session Management Function ‘SMF’ node, and

the second network node is a Unified Data Management ‘UDM’ node.
A method (300) performed by a second network node, comprising:

transmitting (S301) , to a first network node, a request message for subscribing events of a User Equipment ‘UE’ served by the first network node; and

receiving (S303) , from the first network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
The method (300) of claim 8, further comprising:

skipping a request message for unsubscribing/deleting the subscribed events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
The method (300) of claim 8 or 9, wherein the first indication is received from the first network node in a response message for subscribing the events of the UE.
The method (300) of any of claims 8 to 10, wherein the request message for subscribing the events of the UE comprises a second indication indicating that the second network node can skip a request message for unsubscribing/deleting events of the UE upon the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
The method (300) of claim 8 or 9, wherein the first indication is received from the first network node in a deregistration request message received in the deregistration process of the first network node toward the second network node due to the last session of the UE being released by the UE in the first network node.
The method (200) of any of claims 8 to 12, wherein

the first network node is a Session Management Function ‘SMF’ node, and

the second network node is a Unified Data Management ‘UDM’ node.
A first network node (700) , comprising:

at least one processor (701) , and

at least one memory (703) , storing instructions which, when executed on the at least one processor (701) , cause the first network node (700) to:

receive, from a second network node, a request message for subscribing events of a User Equipment ‘UE’ served by the first network node; and

transmit, to the second network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
The first network node (700) of claim 14, wherein the instructions, when executed on the at least one processor (701) , further cause the first network node (700) to perform the method according to any of claims 2 to 7.
A second network node (900) , comprising:

at least one processor (901) , and

at least one memory (903) , storing instructions which, when executed on the at least one processor (901) , cause the second network node (900) to:

transmit, to a first network node, a request message for subscribing events of a User Equipment ‘UE’ served by the first network node; and

receive, from the first network node, a first indication indicating that the subscribed events of the UE stored as at least a part of UE context can be removed locally by the first network node upon a deregistration process of the first network node toward the second network node due to a last session of the UE being released by the UE in the first network node.
The second network node (900) of claim 16, wherein the instructions, when executed on the at least one processor (901) , further cause the second network node (900) to perform the method according to any of claims 9 to 13.
A computer readable storage medium having computer program instructions stored thereon, the computer program instructions, when executed by at least one processor, causing the at least one processor to perform the method according to any of claims 1 to 7.
A computer readable storage medium having computer program instructions stored thereon, the computer program instructions, when executed by at least one processor, causing the at least one processor to perform the method according to any of claims 8 to 13.