Network function subscription

Abstract

An apparatus, method and computer program is described comprising: receiving (at a network function of a communication system) an event exposure subscription request from a network function consumer and generating a response to the event exposure subscription request. The request includes a subscription preference indicating that the subscription be applicable to each network function of a network function set. The response includes an attribute indicating that the request that the subscription be applicable to each network function of the network function set is accepted.

Description

NETWORK FUNCTION SUBSCRIPTIONRelated Applications

[0001] This patent application claims the benefit of priority of United Kingdom Patent Application No. 2312346.6 filed August 11, 2023, which is hereby incorporated by reference as if reproduced in its entirety.Field

[0002] The present specification relates to network function subscription in a communication system.Background

[0003] The present specification relates to network function subscription in which a plurality of network functions of a communication system are provided that are, at least in part, interchangeable.Summary

[0004] In a first aspect, this specification describes a network function (e.g. an access and mobility management function) of a communication system (e.g. a mobile communication system or a wireless communication system), the network function comprising: means for receiving an event exposure subscription request from a network function consumer (e.g. a network exposure function), wherein the request identifies target resources (e.g. user device or user equipments (UEs)) of the communication system to which the requests applies, and wherein the request includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; means for communicating with other network functions in the network function set (e.g. communicating subscription details with other (e.g. all) network functions and / or exchanging information required to generate an aggregate report); means for generating a response to the event exposure subscription request, wherein said response includes an attribute (e.g. a flag) indicating that the request that the subscription be applicable to each network function of the network function set is accepted; and means for providing the generated response to said network function consumer.

[0005] The means for generating said response to the event exposure subscription request may comprise means for combining responses relating to all resources of the event exposure subscription request that are managed by network function instances within the set. The resources of the event exposure subscription request could be all user devices / UEs or could be an identified list of user devices / UEs.

[0006] The response to the event exposure subscription request may include one or more aggregate reports in which information is provided regarding an aggregate state (e.g. an average) of a plurality of resources served by the set of network functions.

[0007] The response to the event exposure subscription request includes one or more atomic reports including information regarding changes of one or more states of individual resources.

[0008] Some example embodiments further comprise: means for modifying the event exposure subscription based on an instruction received from the network function consumer at any network function of the network function set.

[0009] The event exposure subscription request may include an event type (e.g. location, mobility etc,) and one or more event filters (e.g. areas of interest, slices etc.).

[0010] In a second aspect, this specification describes a network function consumer (e.g. a network exposure function) of a communication system (e.g. a mobile communication system or a wireless communication system), the network function consumer comprising: means for sending an event exposure subscription request to a network function of the communication system, wherein the request identifies target resources (e.g. UEs) of the communication system to which the requests applies, and wherein the requests includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; and means for receiving a response to the event exposure subscription request from the network function in response to said event exposure subscription request, said response including an attribute (e.g. a flag) indicating whether the request that the subscription be applicable to each network function of the network function set is accepted.

[0011] The response may include a combination of responses relating to all resources of the event exposure subscription request that are managed by network function instances within the set.

[0012] The response may include one or more aggregate reports in which information is provided regarding an aggregate state of a plurality of resources served by the set of network functions.

[0013] The response may include one or more atomic reports including information regarding changes of state of individual resources.

[0014] Some example embodiments further comprise: means for providing a request to modify the event exposure subscription to a network function of the set.

[0015] The event exposure subscription request may include an event type (e.g. location, mobility etc,) and one or more event filters (e.g. areas of interest, slices etc.).

[0016] In a third aspect, this specification describes a first network function (e.g. a first access and mobility management function) of a communication system (e.g. a mobile communication system or a wireless communication system), the first network function comprising: means for communicating with a second network function that forms part of a network function set with the first network function, including providing reports relating to resources (e.g. UEs) managed by first network function in response to a request from said second network function, wherein said second network function is responsible for an event exposure subscription from a network function consumer relating to said network function set; and means for preserving said event exposure subscription (e.g. by taking over responsibility for / ownership of the subscription) within the network function set in the event of a failure of said second network function.

[0017] The first network function may further comprise: means for modifying the event exposure subscription based on an instruction received from the network function consumer.

[0018] The event exposure subscription request may include an event type (e.g. location, mobility etc,) and one or more event filters (e.g. areas of interest, slices etc.).

[0019] In a fourth aspect, this specification describes a method comprising: receiving, at a network function (e.g. an access and mobility management function) of the communication system (e.g. a mobile communication system or a wireless communication system), an event exposure subscription request from a network function consumer, wherein the request identifies target resources (e.g. user device or user equipments (UEs)) of the communication system to which the request applies, and wherein the requests includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; communicating with other networkfunctions in the network function set; generating a response to the event exposure subscription request, wherein said response includes an attribute (e.g. a flag) indicating that the request that the subscription be applicable to each network function of the network function set is accepted; and providing the generated response to said network function consumer.

[0020] The response to the event exposure subscription request may include one or more aggregate reports in which information is provided regarding an aggregate state (e.g. an average) of a plurality of resources served by the set of network functions. Alternatively, or in addition, the response to the event exposure subscription request includes one or more atomic reports including information regarding changes of one or more states of individual resources.

[0021] The method may comprise modifying the event exposure subscription based on an instruction received from the network function consumer at any network function of the network function set.

[0022] In a fifth aspect, this specification describes a method comprising: sending, from a network function consumer (e.g. a network exposure function) of a communication system (e.g. a mobile or wireless communication system), an event exposure subscription request to a network function of the communication system, wherein the request identifies target resources of the communication system to which the requests applies, and wherein the requests includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; and receiving a response to the event exposure subscription request from the network function in response to said event exposure subscription request, said response including an attribute (e.g. a flag) indicating whether the request that the subscription be applicable to each network function of the network function set is accepted.

[0023] The response may include one or more aggregate reports in which information is provided regarding an aggregate state of a plurality of resources served by the set of network functions. Alternatively, or in addition, the response may include one or more atomic reports including information regarding changes of state of individual resources.

[0024] Some example embodiments further comprise providing a request to modify the event exposure subscription to a network function of the set.

[0025] In a sixth aspect, this specification describes a method comprising: communicating (from a first network function, such as a first access and mobile management function) with a second network function (e.g. a second access and mobile management function) that forms part of a network function set with the first network function, including providing reports relating to resources managed by first network function in response to a request from said second network function, wherein said second network function is responsible for an event exposure subscription from a network function consumer relating to said network function set; and preserving said event exposure subscription (e.g. by taking over responsibility for / ownership of the subscription) within the network function set in the event of a failure of said second network function. The method may further comprise modifying the event exposure subscription based on an instruction received from the network function consumer.

[0026] In a seventh aspect, this specification describes computer-readable instructions which, when executed by a computing apparatus, cause the computing apparatus to perform (at least) any method as described herein (including the methods of the fourth to sixth aspects described above).

[0027] In an eighth aspect, this specification describes a computer-readable medium (such as a non-transitory computer-readable medium) comprising program instructions stored thereon for performing (at least) any method as described herein (including the methods of the fourth to sixth aspects described above).

[0028] In a ninth aspect, this specification describes an apparatus comprising: at least one processor; and at least one memory including computer program code which, when executed by the at least one processor, causes the apparatus to perform (at least) any method as described herein (including the method of the fourth to sixth aspects described above).

[0029] In a tenth aspect, this specification describes an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, causes the apparatus to perform (at least) any method as described herein (including the method of the third or fourth aspects described above).

[0030] In an eleventh aspect, this specification describes a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to: receive, at a network function of the communication system, an event exposure subscription request from a network function consumer, wherein the request identifies target resources of the communication system to which the request applies, and wherein the requests includes asubscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; communicate with other network functions in the network function set; generate a response to the event exposure subscription request, wherein said response includes an attribute indicating that the request that the subscription be applicable to each network function of the network function set is accepted; and provide the generated response to said network function consumer.

[0031] In a twelfth aspect, this specification describes a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to: send, from a network function consumer (e.g. a network exposure function) of a communication system (e.g. a mobile or wireless communication system), an event exposure subscription request to a network function of the communication system, wherein the request identifies target resources of the communication system to which the requests applies, and wherein the requests includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; and receive a response to the event exposure subscription request from the network function in response to said event exposure subscription request, said response including an attribute (e.g. a flag) indicating whether the request that the subscription be applicable to each network function of the network function set is accepted.

[0032] In a thirteenth aspect, this specification describes a computer program comprising instructions which, when executed by an apparatus, cause the apparatus to: communicate (from a first network function, such as a first access and mobile management function) with a second network function (e.g. a second access and mobile management function) that forms part of a network function set with the first network function, including providing reports relating to resources managed by first network function in response to a request from said second network function, wherein said second network function is responsible for an event exposure subscription from a network function consumer relating to said network function set; and preserve said event exposure subscription (e.g. by taking over responsibility for / ownership of the subscription) within the network function set in the event of a failure of said second network function.

[0033] In a fourteenth aspect, this specification describes an input (or some other means) for receiving, at a network function of the communication system, an event exposure subscription request from a network function consumer, wherein the request identifies target resources of the communication system to which the request applies, and wherein the requests includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; a first output (or some other means) for communicating with other network functions in the network function set; a control module (or some other means) for generating a response to the event exposure subscription request, wherein said response includes an attribute indicating that the request that the subscription be applicable to each network function of the network function set is accepted; and a second output (or some other means) for providing the generated response to said network function consumer.

[0034] In a fifteenth aspect, this specification describes an output (or some other means) for sending, from a network function consumer (e.g. a network exposure function) of a communication system (e.g. a mobile or wireless communication system), an event exposure subscription request to a network function of the communication system, wherein the request identifies target resources of the communication system to which the requests applies, and wherein the requests includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; and an input (or some other means) for receiving a response to the event exposure subscription request from the network function in response to said event exposure subscription request, said response including an attribute (e.g. a flag) indicating whether the request that the subscription be applicable to each network function of the network function set is accepted.

[0035] In a sixteenth aspect, this specification describes a communication means (or some other means) for communicating (from a first network function, such as a first access and mobile management function) with a second network function (e.g. a second access and mobile management function) that forms part of a network function set with the first network function, including providing reports relating to resources managed by first network function in response to a request from said second network function, wherein said second network function is responsible for an event exposure subscription from a network function consumer relating to said network function set; and a control module (or some other means) forpreserving said event exposure subscription (e.g. by taking over responsibility for / ownership of the subscription) within the network function set in the event of a failure of said second network function.Brief description of the drawings

[0036] Example embodiments will now be described, by way of non-limiting examples, with reference to the following schematic drawings, in which:

[0037] FIG. 1 is a block diagram showing a system in accordance with an example embodiment;

[0038] FIG. 2 is a flowchart showing an algorithm in accordance with an example embodiment;

[0039] FIG. 3 is a flowchart showing an algorithm in accordance with an example embodiment;

[0040] FIG. 4 is a block diagram showing a system in accordance with an example embodiment;

[0041] FIG. 5 is a block diagram showing a system in accordance with an example embodiment;

[0042] FIGS. 6 to 8 show message flow sequences in accordance with example embodiments;

[0043] FIG. 9 is a flowchart showing an algorithm in accordance with an example embodiment;

[0044] FIG. 10 is a schematic diagram of components of one or more of the example embodiments described previously; and

[0045] FIG. 11 shows tangible media for storing computer-readable code which when run by a computer may perform methods according to example embodiments described herein.Detailed description

[0046] The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in the specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0047] In the description and drawings, like reference numerals refer to like elements throughout.

[0048] FIG. 1 is a block diagram of a system of a communication system (e.g. a mobile communication system or a wireless communication system), indicated generally by the reference numeral 10, in accordance with an example embodiment. The system 10 comprises a first network function 12, a second network function 13 and a third network function 14 that are grouped together as a network function set (NF set) 16. As discussed further below, the network functions of the network function set 16 are, at least in part, interchangeable and may, for example, share the same context data. Sharing context data may enable distribution, redundancy, and scalability.

[0049] The system 10 further comprises a network function consumer 18 that is in two-way communication with the network function set 16. The network function consumer 18 that desires access to a service from the network function set 16 may, for example, select a network function from the set to provide that service.

[0050] FIG. 2 is a flowchart showing an algorithm, method processor, indicated generally by the reference numeral 20, in accordance with an example embodiment. The algorithm 20 may be implemented by the network function consumer (NF consumer) 18.

[0051] The algorithm 20 starts at operation 22, where the network function consumer 18 provides (e.g., sends) a subscription request to the network function set 16. The subscription request includes a request for information from one or more of the network functions 12 to 14. A response to the request is received in operation 24.

[0052] In many of the example embodiments discussed below, the network function consumer (such as the NF consumer 18) is a network exposure function (NEF) of a communication system (e.g. a mobile communication system or a wireless communication system) and the network functions 12 to 14 are access and mobility management functions (AMFs) of the communication system (e.g. a mobile communication system or a wireless communication system). It should be noted that this is not essential to all example embodiments; alternative network functions of a communication system (e.g., a core network of a communication system) and network function consumers of the communication system could be used.

[0053] An AMF can be used to provide one or more UEs (e.g. a plurality of UEs) with access and mobility related event reporting to network functions authorized to subscribe to such event reporting service. In the algorithm 20, the subscription may consist of an event type (e.g., location, mobility, etc.), one or more event filters (e.g. area of interest, slices, etc.), and event reporting attributes (e.g. mode, duration, conditions, etc.).The target of the subscription request 22 could be a bulk subscription involving a group of UE(s) or any UE.

[0054] When a UE that is a target for one or more subscriptions moves to a different network function (e.g. a different AMF), this may be handled as follows:• For specific UE subscriptions, the event subscription is transferred from a source network function to a target network function.• For bulk subscriptions for a group of UEs, the event subscription remains in the source network function however a corresponding group UE event subscription is created in the target network function (unless a corresponding subscription for the group already exists in the target network function).• In case of bulk Subscriptions for “any UE”, the subscription remains within the source network function and the subscription is not transferred / created in the target network function.

[0055] As discussed above, bulk subscription may include a network exposure function (NEF) of a mobile communication system and access and mobility management functions (AMFs); this is not essential. Bulk subscriptions (whether for a group of UEs or any UE) are also used in event exposure services provided by other network functions of a communication system (e.g., a core network of a communication system), For example:• A network exposure function (NEF) may subscribe to a session management function (SMF) for event notifications on a specified protocol data unit (PDU) session, or for all PDU Sessions of a group of UE(s) or any UE.• An application function (AF) may subscribe to a policy control function (PCF) for any UE and receive reports associated to a specific Application Identifier or DNN, S-NSSAI.• A network data analytics functions (NWDAF) may subscribe to a user plane function (UPF) to collect information for network data analytics that correspond to any UE for certain DNN, S-NSSAI, Area of Interest, Application server IP address / FQDN, APP ID, DNAI, etc.

[0056] The skilled person will be aware of further example uses of bulk subscription procedures in additional to those described herein.

[0057] Event reports for bulk subscriptions may be grouped in two types: aggregate (or complete) state reports and atomic (or update) state reports.

[0058] Aggregate state reports provide information regarding the aggregate state of all monitored targets served by the relevant network function producer (e.g. the network functions 12 to 14 in the system 10 described above). The aggregate state reports may include information about the state or activity of multiple target resources. Examples of elements of such report include:• The “current” and “last known” state for a One Time or Immediate Reachability-Report• The “current” and “last known” state for a One Time or Immediate Time-Zone Report• A Frequent-Mobility-Registration Periodic Report• UEs-In-Area One Time, Continuous or Periodic Reports

[0059] In contrast, atomic state reports provide information about changes in the state of a particular target. The consumer would typically have previously received a corresponding aggregate report in order to have a complete view of the state of the target resources in the NF Producer. Examples of such reports in the AMF Event Exposure Service include: state updates for continuous Reachability Report; and state updates for continuous time-zone report.

[0060] When an event exposure subscription refers to a specific resource (e.g. a single UE, single PDU Session), a specific NF Instance within the NF Set “owns” the subscription and provides reporting for the resource. Furthermore, in case the initially assigned NF Instance within the set becomes out of service and the resource is re-assigned to an alternate NF Instance within the NF Set, that NF also undertakes the subscription ownership and reporting responsibility.

[0061] A network function may become stateless by decoupling the "compute" resource and "storage" resource. However, the state awareness level may vary in different NF Set implementations .

[0062] In “partially stateless” NF Set implementations, under normal conditions individual target resources (e.g., UEs, PDUs) are correlated to a specific NF Instance. Resource ownership may be transferred from one NF in the set to another only “per need basis” such asNF failures, load rebalancing, planned removal etc. In such implementations, each NF Producer provides reporting only for the resources it is currently serving thus NF Consumers must maintain a separate event exposure bulk subscription towards each NF Instance in the Set. AMF implementations typically follow such NF Set architecture where a UE and its relevant resources like PDUs are correlated to a GUAMI that refers to a single AMF instance.

[0063] In “fully stateless” NF Set implementations, there is no specific correlation between individual resources and NF Instances (e.g. a UDM Set implementation where all shared resources are stored and retrieved via a common UDSF and UDR). Such implementations may have a delegation / leader election mechanism to decide which NF instance will “own” a specific event exposure bulk subscription and be responsible to accomplish reporting for all involved resources on behalf of the whole NF Set.

[0064] In contrast, in the case of bulk subscriptions, such as the subscription request in the operation 22, referring to multiple resources (e.g. a group of UEs or Any UE) the subscription ownership, reporting responsibility and stickiness within the NF Set could be unclear and may depend on the state awareness level of the NF Set implementation (i.e. “partially-stateless” vs. “full-stateless”).

[0065] The lack of clear subscription scope and ownership of the event subscription may lead to reporting consistency issues. For example:• Multiple / overlapping reports in which the NF Consumer is unaware whether the creation of a separate subscription towards each NF instance in the NF Set is required. If this is unnecessary, but nevertheless multiple subscriptions are created, all NFs within the NF Set may be providing reports for the same subscription and resources. Furthermore, the NF Consumer may not be able to distinguish whether each report should be considered as a complete report related to all resources of the set, or if the reports from all NF Instances in the NF set must be aggregated (e.g. it could be unclear if a Dispersion Analytics Event Report from an SMF regarding the total transactions related to a Slice refer to the PDUs “owned” by that SMF only, or all the PDUs served by all SMFs in the Set).• Incomplete reports could be generated if no NF in a particular set considers itself to be responsible for a resource that is not correlated to a specific NF Instance. Certain event may therefore be unreported.

[0066] Accordingly, lack of NF Set level support for event exposure bulk subscriptions may degrade reliability and efficiency as follows:• Bulk subscription loss upon single NF Producer failure. This could be especially relevant for “Any UE” bulk subscriptions but may also happen in “group UE” type of event subscriptions where the NF producer failure occurs before the subscription is activated via any of the UE(s) that belong to the group in another NF in the set. This means that NF Consumer may be required to constantly monitor the state of the network function and recreate the subscription whenever the NF Consumer detects that the network functions has failed or restarted.• Suboptimal signaling. NF Consumers may discover, subscribe, and receive reports from each NFs in the NF set instead of having a single subscription via which they can reports for all the relevant resources within the NF Set.

[0067] FIG. 3 is a flowchart showing an algorithm, method or process, indicated generally by the reference numeral 30, in accordance with an example embodiment. The algorithm 30 is implemented by a NF function of a plurality of network functions of a communication system (e.g. a mobile communication system or a wireless communication system). The plurality of NFs are part of a network function set and the plurality of network functions are at least partially interchangeable.

[0068] The algorithm 30 starts at operation 32, where a bulk subscription request (e.g. an event exposure subscription request) is received, from a network function consumer (such as an NEF), at one of a plurality of network functions that are at least partially interchangeable. The request identifies target resources (such as UE(s)) of the mobile communication system to which the requests applies. The request also includes a subscription preference requesting that the subscription be applicable to each network function of a network function set. The event exposure subscription request may include an event type (e.g. location mobility) and one or more event filters (e.g. areas of interest, slices).

[0069] At operation 34, the network function receiving the bulk subscription request communicates with the other network functions in the network function set. This communication may include sharing the subscription details with other (e.g. all) network functions in the set. Moreover, if an aggregate report is to be prepared, then the network functions may additionally exchange the info required to prepare such a report.

[0070] At operation 36, a response to the event exposure subscription request is generated. The response includes an attribute indicating that the request that the subscription be applicable to each network function of the network function set is accepted. The attribute maybe a flag. If this flag is missing, then this may indicate that the NF set level bulk subscription procedure described herein is not supported (as a result, the network function instance making the bulk subscription procedure will know not to use the procedure).

[0071] The operation 36 may combine responses relating to all resources (i.e. all resources that are part of the initial request - this could be “all UEs” or could be an identified list of UEs) of the event exposure subscription request that are managed by network function instances within the set. Note that the response could be generated at a different network function of the set.

[0072] As noted above, the response to the event exposure subscription request may include one or more aggregate reports (in which information is provided regarding an aggregate state (e.g. an average) of a plurality of resources served by the set of network functions) or one or more atomic reports (including information regarding changes of one or more states of individual resources).

[0073] At operation 38, the response generated in the operation 36 is provided (e.g., sent) to the network function consumer.

[0074] Thus, the algorithm 30 enables a NF consumer to indicate a preference to create an NF set level event exposure bulk subscriptions, with a response to the relevant request indicating whether that preference is accepted. This may have the advantage of enabling backwards compatibility within communicaton systems that cannot implement the subscription described herein.

[0075] In the event that the new subscription format is supported, a single event exposure bulk subscription is applicable for the whole NF Set, such that:• Event Reports may refer to the aggregate of all the resources managed by all NF instances within the set• The exposure bulk subscription resource may be applicable throughout the NF set.• It may be possible to update or delete the event bulk subscription via any NF instance in the NF set.• The exposure bulk subscription may be deemed to be available even when the NF instance via which the subscription was created fails / restarts

[0076] In the event that the new subscription format is not supported, the event exposure bulk subscription may be handled as follows:Event Reports may refer only to the resources managed by the specific NF instance.• The event exposure bulk subscription resource may be applicable only for the specific NF instance.• The event exposure bulk subscription may be considered lost even when the NF instance via which the subscription was created fails / restarts.

[0077] FIG. 4 is a block diagram showing a system, indicated generally by the reference numeral 40, in accordance with an example embodiment. The system 40 comprises a first network function producer 42, a second network function producer 43 and a third network function producer 44 that are grouped together as a network function set (NF set) 46. The network function producers are in two-way communication with each other. As discussed elsewhere herein, the network function producers of the network function set 46 are, at least in part, interchangeable. The system 40 further comprises a network function consumer 48 that is in two-way communication with the network function set 46.

[0078] Each network function producer of the network function set 46 is configured to communicate with other network function producers of the network function set, including providing reports relating to resources managed by the respective network function in response to a request from another network function (e.g. if said another network function is responsible for an event exposure subscription from the network function consumer 48). Each network function producer is configured to preserve said event exposure subscription within the network function set in the event of a failure of said second network function (e.g. by taking over responsibility for the subscription).

[0079] Each network function producer is configured to modify the event exposure subscription based on an instruction received from the network function consumer. Thus, a subscription does not need to be modified by a particular network function producer that is current responsible for the event exposure subscription.

[0080] In order to implement the NF Set level event exposure bulk subscriptions described herewith, the NF consumer 48 that supports the NF set level event exposure bulk subscriptions may send a Subscription Request to any of the NF producers 42 to 44 belonging to NF set 46. The subscription request includes an attribute that indicates that the subscription should preferably apply to the whole NF Set.

[0081] The respective NF producer may or may not support NF set level bulk subscription as a whole, or for the specific bulk subscription. No matter whether the NF set level bulksubscription is supported, the subscription can be accepted; however only NF producers supporting / accepting the NF set bulk subscription protocol described herein for the specific event will include in the response the attribute that indicates that the bulk subscription was accepted at NF set level.

[0082] Moreover, in some example embodiments, if one of the NF producers 42 to 44 receives a bulk subscription request without the indication that a NF Set level subscription is preferred, that NF producer is required to create the bulk subscription on NF Instance level even if it supports NF Set level bulk subscriptions. Thus, for backwards compatibility purposes, the NF producers may be allowed to downgrade the service that they can provide, but not upgrade the requested scope of a bulk subscription.

[0083] If the respective NF Producer did not indicate that the bulk subscription was accepted on NF Set level, the NF consumer 48 may assume that the bulk subscription is only applicable on NF Instance level. This means that:• It would not be possible to reuse the same subscription ID via another NF instance in the set in order to modify or delete the bulk subscription.• The bulk subscription should be considered as lost when the NF Instance fails / restarts.• All event reports are sent exclusively by the NF Instance to which the subscription was made.• Aggregate / complete state event reports (as discussed above) only refer to the resources managed by the specific NF instance and not to the whole NF set. For example, an SMF Dispersion Analytics Event Report regarding the transactions of a slice refers to the transactions handled only by the specific SMF and not the aggregate of the transactions in all SMFs in the SMF set for that slice.• If the NF consumer 48 needs to get reports for all resources within the NF set, the NF consumer should create a separate bulk subscription towards each NF instance in the set.

[0084] If the respective NF producer of the set 46 indicates that the bulk subscription is accepted on NF Set level, the NF consumer 48 may assume that the bulk subscription scope is applicable on NF Set level. This means that:• The event subscription resource is applicable throughout the NF set. That means that it is possible to use the same subscription identifier to update or delete the bulk subscription via any NF instance in the NF Set.• The event bulk subscription should be considered available even when the NF instance via which the subscription was created fails / restarts.• The standard frameworks of NF (Service) instance discovery / selection, redirection and (re)binding can also be used for NF Set level bulk subscriptions.• Atomic / Update Reports may be sent by any NF Producer in the NF set (e.g. the NF Producer sending the notification may be different from the NF via which the event bulk subscription was created). However, for a specific event only a single report shall be sent by one of the NFs in the set.• Aggregate / Complete state event reports (as discussed above) may refer to the aggregate resources managed by all NF instances within the Set. For example:■ A Dispersion Analytics Event Report from an SMF regarding for total transactions within a slice refers to the aggregate of all transactions in all SMFs of the SMF set for that slice.■ An AMF will create an aggregate report of the UE Access behaviour trends for all UEs who belong to the target UE group and are served by any AMF within the AMF set.

[0085] The NF Producer sending the notification may be different from the NF via which the Event bulk subscription was created. However, for a specific aggregate event report, only a single report should be sent by one of the NFs in the set.

[0086] An alternative implementation is that each NF Producer in the in the NF set 46 sends a “partial” aggregate report that includes only the resources owned by the specific NF Instance. In this case the event report API may be extended with an indication that the report is partial and an identifier of the NF Producer sending the report (the latter may be required since reports from all NF in the NF Set now use the same subscription Correlation ID, the NF Consumer cannot use it to distinguish the sender).

[0087] FIG. 5 is a block diagram showing a system, indicated generally by the reference numeral 50, in accordance with an example embodiment. They system 50 is a specific implementation of the system 40 described above.

[0088] The system 50 comprises a first AMF 52, a second AMF 53 and a third AMF 54 (which are examples of the network function producers 42 to 44 described above) that are grouped together as a network function set (NF set) 56. The AMFs 52 to 54 are in two-way communication with each other and are, at least in part, interchangeable. The system 50 further comprises a network exposure function (NEF) 58 that is an example of the network function consumer 48 described above.

[0089] FIG. 6 shows a message flow sequence, indicated generally by the reference numeral 60, in accordance with an example embodiment. The message flow sequence 60 (generally reference to a sequence 60 hereinafter) is implemented using the system 50 described above. The message flow sequence 60 illustrates messages and operations performed by the NEF 58 and AMFs 52, 52, 54 of the system 50. The message flow sequence 60 provides an overview of a call flow where a NF Set level event exposure bulk subscription including a request for an immediate report is successfully created.

[0090] The sequence 60 includes an event exposure request 62 that is sent by the NEF 58 to one of the AMFs of the NF set (the second AMF 53 in this example). The event exposure request includes the NF Set Level Subscription preference flag. The event exposure request may be a Namf_EventExposure request.

[0091] The sequence 60 also includes a subscription response 64 (e.g., a response to the event exposure request) containing an event report list containing aggregate information representing the status of all the resources within the whole NF set. The subscription response 64 may include information such as: identifiers of other relevant network functions, information. Note that the sharing of subscriptions within the set may rely on UDSF (e.g. all NFs subscribing to a shared resource in UDSF being a collection of all NF Set Level Bulk subscriptions) or on other means.

[0092] FIG. 7 shows a message flow sequence, indicated generally by the reference numeral 70, in accordance with an example embodiment. The message flow sequence 70 is implemented using the system 50 described above.

[0093] The sequence 70 includes an event exposure request 72 that is sent by the NEF 58 to one of the AMFs of the NF set (the second AMF 53 in this example). The request includes the NF Set Level Subscription preference flag.

[0094] In the message sequence 70, the AMF 53 does not support the NF Set level bulk subscription and it was downgraded to NF instance level. The NEF 58 subsequently creates bulk subscriptions to each AMF within the set (see messages 76 and 78).

[0095] FIG. 8 shows a message flow sequence, indicated generally by the reference numeral 80, in accordance with an example embodiment. The message flow sequence 80 (referred to a sequence 80 hereinafter) is implemented using the system 50 described above.

[0096] The sequence 80 includes an event exposure request 82 that is sent by the NEF 58 to one of the AMFs of the NF set (the second AMF 53 in this example). The request includes the NF Set Level Subscription preference flag.

[0097] The sequence 80 also includes a subscription response 84 containing an event report containing aggregate information representing the status of all the resources within the whole NF Set, however the update / atomic Reports are sent from a different NF in the set.

[0098] FIG. 9 is a flowchart showing an algorithm, method or process, indicated generally by the reference numeral 90, in accordance with an example embodiment. The algorithm 90 may be implemented by a network function of NF set.

[0099] The algorithm 90 starts at operation 92, where a request to modify the event exposure subscription described herein is provided to the network function of the NF set. Note that in at least some embodiments, the request does not need to be provided to the network function handling the request.

[0100] At operation 94, the event exposure subscription is modified based on the instruction received in operation 92. In some example embodiments, the instruction may be provided at any network function of the respective network function set (e.g. any of the NF producers 42 to 44 or any of the AMFs 52 to 54).

[0101] A number of example embodiments have been described above. Advantages of at least some of the embodiments include:• Backwards compatibility: If either the NF consumer or the NF producer does not support NF Set level event exposure bulk subscriptions, the solution can automatically using existing NF Instance level subscriptions.Implementation agility: The NF producers may be allowed to support NF Set level subscriptions only for the subset of the events Reports since support may be negotiated at the time of the subscription creation.Improved subscription robustness: Event bulk subscriptions can be maintained even after single NF instance failure achieving same level of resilience as subscriptions for individual resources• Optimized signaling: NF consumers may need to maintain only a single subscription via which they can receive reports for all the relevant resources within the NF Set.

[0102] For completeness, FIG. 10 is a schematic diagram of components of one or more of the example embodiments described previously, which hereafter are referred to generically as a processing system 300. The processing system 300 may, for example, be otherwise referred to as an apparatus.

[0103] The processing system 300 may have a processor 302, a memory 304 coupled to the processor and comprised of a RAM 314 and a ROM 312, and, optionally, a user input 310 and a display 318. The processing system 300 may comprise one or more network / apparatus interfaces 308 for connection to a network / apparatus, e.g. a modem which may be wired or wireless. The network / apparatus interface 308 may also operate as a connection to other apparatus such as device / apparatus which is not a network side apparatus. Thus, direct connection between devices / apparatus without network participation is possible.

[0104] The processor 302 is connected to each of the other components in order to control operation thereof.

[0105] The memory 304 may comprise a non-volatile memory, such as a hard disk drive (HDD) or a solid state drive (SSD). The ROM 312 of the memory 304 stores, amongst other things, an operating system 315 and may store software applications 316. The RAM 314 of the memory 304 is used by the processor 302 for the temporary storage of data. The memory 304 may include code which, when executed by the processor 302 cause the processing system 300 to carry out or perform the algorithms 20, 30, and 90 described above. Note that in the case of small device / apparatus the memory can be most suitable for small size usage i.e. not always a hard disk drive (HDD) or a solid state drive (SSD) is used.

[0106] The processor 302 may be for instance, a microcontroller, a plurality of microcontrollers, a processor, or a plurality of processors.

[0107] The processing system 300 may be a standalone computer, a server, a console, a distributed computing system, or a cloud computing system.

[0108] In some example embodiments, the processing system 300 may also be associated with external software applications. These may be applications stored on a remote server device / apparatus and may run partly or exclusively on the remote server device / apparatus. These applications may be termed cloud-hosted applications. The processing system 300 may be in communication with the remote server device / apparatus in order to utilize the software application stored there.

[0109] FIG. 11 shows a tangible media, in the form of a removable memory unit 365, storing computer-readable code which when run by a computer may perform methods according to example embodiments described above. The removable memory unit 365 may be a memory stick, e.g. a USB memory stick, having internal memory 366 storing the computer-readable code. The internal memory 366 may be accessed by a computer system via a connector 367. Of course, other forms of tangible storage media may be used, as will be readily apparent to those of ordinary skilled in the art. Tangible media can be any device / apparatus capable of storing data / information which data / information can be exchanged between devices / apparatus / network.

[0110] Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and / or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a “memory” or “computer-readable medium” may be any non-transitory media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0111] Reference to, where relevant, “computer-readable medium”, “computer program product”, “tangibly embodied computer program” etc., or a “processor” or “processing circuitry” etc. should be understood to encompass not only computers having differing architectures such as single / multi-processor architectures and sequencers / parallel architectures, but also specialised circuits such as field programmable gate arrays FPGA, application specify circuits ASIC, signal processing devices / apparatus and other devices / apparatus. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device / apparatus as instructions for a processor orconfigured or configuration settings for a fixed function device / apparatus, gate array, programmable logic device / apparatus, etc.

[0112] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the abovedescribed functions may be optional or may be combined. Similarly, it will also be appreciated that the flow diagrams and sequences of Figures 2, 3 and 6 to 9 are examples only and that various operations depicted therein may be omitted, reordered and / or combined.

[0113] It will be appreciated that the above described example embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the present specification.

[0114] Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom, new claims may be formulated to cover any such features and / or combination of such features.

[0115] Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described example embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[0116] It is also noted herein that while the above describes various examples, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

Claims1. A network function of a communication network, the network function comprising: means for receiving an event exposure subscription request from a network function consumer, wherein the request identifies target resources of the communication system to which the requests applies, and wherein the request includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; means for communicating with other network functions in the network function set; means for generating a response to the event exposure subscription request, wherein said response includes an attribute indicating that the request that the subscription be applicable to each network function of the network function set is accepted; and means for providing the generated response to said network function consumer.

2. The network function as claimed in claim 1, wherein: the means for generating said response to the event exposure subscription request comprises means for combining responses relating to all resources of the event exposure subscription request that are managed by network function instances within the set.

3. The network function as claimed in claim 1 or claim 2, wherein the response to the event exposure subscription request includes one or more aggregate reports in which information is provided regarding an aggregate state of a plurality of resources served by the set of network functions.

4. The network function as claimed in any one of claims 1 to 3, wherein the response to the event exposure subscription request includes one or more atomic reports including information regarding changes of one or more states of individual resources.

5. The network function as claimed in any one of claims 1 to 4, further comprising: means for modifying the event exposure subscription based on an instruction received from the network function consumer at any network function of the network function set.

6. The network function as claimed in any one of claims 1 to 5, wherein the event exposure subscription request includes an event type and one or more event filters.

7. A method of a network function of a communication network, the method comprising: receiving an event exposure subscription request from a network function consumer, wherein the request identifies target resources of the communication system to which the requests applies, and wherein the request includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; communicating with other network functions in the network function set; generating a response to the event exposure subscription request, wherein said response includes an attribute indicating that the request that the subscription be applicable to each network function of the network function set is accepted; and providing the generated response to said network function consumer.

8. The method as claimed in claim 7, wherein: the generating said response to the event exposure subscription request comprises combining responses relating to all resources of the event exposure subscription request that are managed by network function instances within the set.

9. The method as claimed in claim 7 or claim 8, wherein the response to the event exposure subscription request includes one or more aggregate reports in which information is provided regarding an aggregate state of a plurality of resources served by the set of network functions.

10. The method as claimed in any one of claims 7 to 9, wherein the response to the event exposure subscription request includes one or more atomic reports including information regarding changes of one or more states of individual resources.

11. The method as claimed in any one of claims 7 to 10, further comprising:modifying the event exposure subscription based on an instruction received from the network function consumer at any network function of the network function set.

12. The method as claimed in any one of claims 7 to 11, wherein the event exposure subscription request includes an event type and one or more event filters.

13. A network function consumer of a communication system, the network function consumer comprising: means for sending an event exposure subscription request to a network function of the communication system, wherein the request identifies target resources of the communication system to which the requests applies, and wherein the requests includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; and means for receiving a response to the event exposure subscription request from the network function in response to said event exposure subscription request, said response including an attribute indicating whether the request that the subscription be applicable to each network function of the network function set is accepted.

14. The network function consumer as claimed in claim 13, wherein the response includes a combination of responses relating to all resources of the event exposure subscription request that are managed by network function instances within the set.

15. The network function consumer as claimed in claim 13 or claim 14, wherein the response includes one or more aggregate reports in which information is provided regarding an aggregate state of a plurality of resources served by the set of network functions.

16. The network function consumer as claimed in any one of claims 7 to 9, wherein the response includes one or more atomic reports including information regarding changes of state of individual resources.

17. The network function consumer as claimed in any one of the claims 7 to 10, further comprising:means for providing a request to modify the event exposure subscription to a network function of the set.

18. A method of a network function consumer of a communication system, the method comprising: sending an event exposure subscription request to a network function of the communication system, wherein the request identifies target resources of the communication system to which the requests applies, and wherein the requests includes a subscription preference indicating that the subscription be applicable to each network function of a network function set, wherein the network function is one of a plurality of network functions of said set that are, at least in part, interchangeable; and receiving a response to the event exposure subscription request from the network function in response to said event exposure subscription request, said response including an attribute indicating whether the request that the subscription be applicable to each network function of the network function set is accepted.

19. The method as claimed in claim 18, wherein the response includes a combination of responses relating to all resources of the event exposure subscription request that are managed by network function instances within the set.

20. The method as claimed in claim 18 or claim 19, wherein the response includes one or more aggregate reports in which information is provided regarding an aggregate state of a plurality of resources served by the set of network functions.

21. The method as claimed in any one of claims 18 to 20, wherein the response includes one or more atomic reports including information regarding changes of state of individual resources.

22. The method as claimed in any one of the claims 18 to 21, further comprising: providing a request to modify the event exposure subscription to a network function of the set.

23. A first network function of a communication system, the first network function comprising:means for communicating with a second network function that forms part of a network function set with the first network function, including providing reports relating to resources managed by first network function in response to a request from said second network function, wherein said second network function is responsible for an event exposure subscription from a network function consumer relating to said network function set; and means for preserving said event exposure subscription within the network function set in the event of a failure of said second network function.

24. The first network function as claimed in claim 23, further comprising: means for modifying the event exposure subscription based on an instruction received from the network function consumer.

25. A method of a first network function of a communication system, the method comprising: communicating with a second network function that forms part of a network function set with the first network function, including providing reports relating to resources managed by first network function in response to a request from said second network function, wherein said second network function is responsible for an event exposure subscription from a network function consumer relating to said network function set; and preserving said event exposure subscription within the network function set in the event of a failure of said second network function.

26. The method as claimed in claim 25, further comprising: modifying the event exposure subscription based on an instruction received from the network function consumer.

27. A computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform the method of any of claims 7 to 12 or claims 18 to 22, or claims 25 to 26.

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