Techniques for event exposure subscriptions in dual-core networks

Abstract

Embodiments include methods for an exposure function configured to operate in a communication network that includes a first core network and a second core network. Such methods include sending, to a first data management function of the first core network, a first event exposure (EE) subscription request for notifications from the first core network related to a user equipment (UE). The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE. Such methods include receiving, from the first data management function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and a second indication of whether a subscription for the UE exists in the second core network. Such methods include, based on the second indication, selectively sending to the second data management function a second EE subscription request for notifications from the second core network related to the UE. Other embodiments include complementary methods for the first data management function.

Description

[0001] TECHNIQUES FOR EVENT EXPOSURE SUBSCRIPTIONS IN DUAL-CORE NETWORKS

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to communication networks that include two different core networks, and more specifically to techniques for managing subscriptions by network functions (NF s) to notifications of events related to a user equipment (UE) that may have a subscription in either or both of the two core networks.

[0004] BACKGROUND

[0005] Long-Term Evolution (LTE) is an umbrella term that refers to fourth-generation radio access technologies developed within 3GPP and initially standardized in Release 8 (Rel-8) and Release 9 (Rel-9), also known as Evolved UTRAN (E-UTRAN). LTE is targeted at various licensed frequency bands and is accompanied by improvements to non-radio aspects commonly referred to as System Architecture Evolution (SAE), which includes Evolved Packet Core (EPC) network.

[0006] Figure 1 shows an exemplary architecture for an LTE network. The network shown in Figure 1 includes an Evolved UTRAN (E-UTRAN, 100) includes one or more evolved Node B’s (eNBs, e.g., 105, 110, 115) and one or more user equipment (UEs, e.g., 120). The eNBs are responsible for radio-related functions in the LTE network, including radio bearer control, radio admission control, radio mobility control, scheduling, and dynamic allocation of resources to UEs in uplink and downlink, as well as security of the communications with the UE . Each eNB can serve a geographic coverage area including one or more cells (e.g., 106, 111, and 115).

[0007] The eNBs communicate with each other via the X2 interface and with the Evolved Packet Core (EPC) network (130) via the SI interface, specifically with the Mobility Management Entity (MME) and the Serving Gateway (SGW), as exemplified by MME / S-GWs (134, 138) in Figure 1. MME / S-GW handles both the overall control of the UE and data flow between the UE and the rest of the EPC. More specifically, MME processes the signaling (e.g., control plane) protocols between UE and EPC, which are known as the Non-Access Stratum (NAS) protocols. In contrast, the S-GW handles all Internet Protocol (IP) data packets (e.g. , user plane) between UE and EPC and serves as the local mobility anchor for data bearers when the UE moves between eNBs.

[0008] The EPC also includes a Home Subscriber Server (HSS, 131), which manages user- and subscriber-related information. The HSS can also provide support functions in mobility management, call and session setup, user authentication and access authorization. The HSS functions can be related to the functions of legacy Home Location Register (HLR) and Authentication Centre (AuC) functions or operations. The HSS can communicate with the MMEs via respective S6a interfaces. In some embodiments, the HSS can communicate with a user data repository (EPS-UDR, e.g., 135) via a Ud interface. The EPS-UDR can store user credentials after they have been encrypted by AuC algorithms. EPS-UDR is also referred to as 4G-UDR.

[0009] Additionally, the EPC can include a Service Capabilities Exposure Function (SCEF, 139), which was introduced in Rel-13 to securely expose the services and capabilities provided by the 3GPP network interfaces. For example, the SCEF can expose services and capabilities provided by the HSS to application servers (AS) internal or external to the LIE network. As a more specific example, a machine-type communication (MTC) application hosted by an AS may communicate directly with the SCEF or via an intermediate a Services Capability Server (SCS), which communicates with MTC UEs in the LTE network. In this way, the SCEF provides access to network capabilities through homogenous network application programming interfaces (APIs), thereby abstracting services from the underlying 3GPP network interfaces and protocols.

[0010] Currently the fifth generation (5G) of cellular systems is being standardized by the Third- Generation Partnership Project (3 GPP). NR is developed for maximum flexibility to support a variety of different use cases. These include MTC, enhanced mobile broadband (eMBB), ultrareliable low latency communications (URLLC), side-link device-to-device (D2D), and several other use cases.

[0011] One change in 5G networks is that traditional peer-to-peer interfaces and protocols found in earlier-generation networks (e.g., EPC) are modified and / or replaced by a Service Based Architecture (SB A) in which Network Functions (NFs) provide one or more services to one or more service consumers. This can be done, for example, by Hyper Text Transfer Protocol / Representational State Transfer (HTTP / REST) application programming interfaces (APIs). In general, the various services are self-contained functionalities that can be changed and modified in an isolated manner without affecting other services. Furthermore, the services are composed of various “service operations”, which are more granular divisions of the overall service functionality. The 5G SBA model is based on principles of modularity, reusability, and self -containment, which can enable network deployments to take advantage of the latest virtualization and software technologies.

[0012] In the 5G SBA, network repository functions (NRF) allow every network function to discover the services offered by other network functions, and Data Storage Functions (DSF) allow every network function to store its context. The Unified Data Management (UDM) function supports generation of 3GPP authentication credentials, user identification handling, access authorization based on subscription data, and other subscriber -related functions. In other words, the UDM provides similar functionality for 5GC as HSS does for EPC. A Network Exposure Function (NEF) acts as entry point into an operator's core network (CN), by securely exposing network capabilities and events provided by other NFs and by providing ways for application functions (AFs) to securely provide information to (or receive information from) the CN. When an operator deploys both EPC (4G) and 5GC (5G) networks, the SCEF and NEF functionality may be combined into a single entity, referred to herein as SCEF / NEF.

[0013] SUMMARY

[0014] In networks that support both 4G and 5G, an AS / SCS or an AF may subscribe via SCEF / NEF for event notifications related to a particular UE (also referred to as “event exposure” or EE). The SCEF / NEF sends the EE subscription request to UDM, to HSS, or to both. When the E subscription request is sent to UDM, the UDM returns a success message if the UE has a 5G subscription or an error message if the UE does not have a 5G subscription. However, neither message informs the SCEF / NEF whether the UE has a 4G subscription. This can create various problems, issues, and / or difficulties.

[0015] 3GPP TS 23.632 (vl8.2.0) clause 5.6 describes “common network exposure scenarios” in which an SCEF / NEF can configure monitoring events applicable to bothEPC and 5GC using only 5GC procedures towardsUDM. In cases where theUE of interest does not have a 5G subscription, the UDM will return to SCEF / NEF an error indicating USER NOT FOUND . This leaves ambiguity about whether the UE of interest has a 4G subscription, which can create various problems, issues, and / or difficulties.

[0016] An object of embodiments of the present disclosure is to improve EE subscriptions in networks that support both 4G and 5G, such as by facilitating solutions to exemplary problems summarized above and described in more detail below.

[0017] Some embodiments of the present disclosure include methods (e.g., procedures) for an exposure function configured to operate in a communication network that includes a first core network and a second core network.

[0018] These exemplary methods include sending, to a first data management function of the first core network, a first EE subscription request for notifications from the first core network related to a UE. The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE. These exemplary methods include receiving, from the first data management function, a first EE subscription response including the following:

[0019] • a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and • a second indication of whether a subscription for the UE exists in the second core network; and

[0020] These exemplary methods include, based on the second indication, selectively sending to the second data management function a second EE subscription request for notifications from the second core network related to the UE.

[0021] In some embodiments, when the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the first core network, the first EE subscription response also includes a further second indication of whether a subscription for the UE exists in the first core network.

[0022] Other embodiments include methods (e.g., procedures) for a first data management function configured to operate in a first core network of a communication network that also includes a second core network. In general, these embodiments are complementary to the methods for an exposure function that were summarized above.

[0023] These exemplary methods include receiving, from an exposure function of the communication network, a first EE subscription request for notifications from the first core network related to a UE. The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related totheUE. These exemplary methods include determining whether a subscription for the UE exists in the first core network and whether a subscription for the UE exists in the second core network. These exemplary methods include, when it is determined that a subscription for the UE exists in the first core network, attempting to create an EE subscription for notifications from the first core network related to the UE, in accordance with the first EE subscription request . These exemplary methods include sending, to the exposure function, a first EE subscription response including the following:

[0024] • a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and

[0025] • a second indication of whether a subscription for the UE exists in the second core network.

[0026] In some embodiments, when the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the first core network, the first EE subscription response also includes a further second indication of whether a subscription for the UE exists in the first core network.

[0027] In some embodiments, the first core network is a 5G core network (5GC), the second core network is a 4G evolved packet core network (EPC), the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF), the first data management function is a unified data management (UDM) function, and the second data management function is a home subscriber server (HSS).

[0028] These exemplary methods include sending, to a first data management function of the first core network, a first event exposure (EE) subscription request for notifications from the first core network related to a UE. The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related totheUE. These exemplary methods also include receiving, from the first data management function, a first EE subscription response including the following:

[0029] • a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, and

[0030] • a second indication that a subscription for the UE does not exist in the first core network. These exemplary methods also include, where based on the first indication, selectively sending to the second data management function a second EE subscription request for notifications from the second core network related to the UE

[0031] In some embodiments, the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network. In some of these embodiments, the first EE subscription request includes an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required. In some variants of these embodiments, the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event. In some variants of these embodiments, the first EE subscription request also includes an indication for immediate event reporting.

[0032] Other embodiments include methods (e.g., procedures) for a first data management function configured to operate in a first core network of a communication network that also includes a second core network. In general, these embodiments are complementary to the methods for an exposure function that were summarized above.

[0033] These exemplary methods include receiving, from an exposure function of the communication network, a first EE subscription request for notifications from the first core network related to a UE. The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related totheUE. These exemplary methods also include determining that a subscription forthe UE does not exist in the first core network. These exemplary methods also include determining the following:

[0034] • whether user subscription data for the second core network is accessible to the first data management function, and • if determined to be accessible, whether the user subscription data for the second core network includes a subscription for the UE;

[0035] These exemplary methods also include attempting to create an EE subscription for notifications from the second core network related to the UE, in accordance with the first EE subscription request, in response to each of the following conditions:

[0036] • the user subscription data for the second core network includes a subscription for the UE; and

[0037] • the first data management function is unable to determine whether the user subscription data for the second core network includes a subscription for the UE.

[0038] These exemplary methods also include sending, to the exposure function, a first EE subscription response including the following:

[0039] • a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, and

[0040] • a second indication that a subscription for the UE does not exist in the first core network.

[0041] In some of these embodiments, the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network. In some variants of these embodiments, the first and second EE subscription requests include an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required. In some further variants, the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event. In some further variants, the first EE subscription request also includes an indication for immediate event reporting.

[0042] Other embodiments include methods (e.g., procedures) for a second data management function configured to operate in a second core network of a communication network that also includes a first core network. In general, these embodiments are complementary to the methods for an exposure function and for a first data management function that were summarized above.

[0043] These exemplary methods include receiving, from a first data management function of the first core network, a second EE subscription request for notifications from the second core network related to a UE. A subscription for the UE does not exist in the first core network. These exemplary methods also include attempting to create an EE subscription for notifications from the second core network related to the UE, in accordance with the second EE subscription request. These exemplary methods also include sending to the first data management function a second EE subscription response including a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network. In some embodiments, the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network. In some of these embodiments, the second EE subscription request includes an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required. In some variants of these embodiments, the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event. In some variants of these embodiments, the second EE subscription request also includes an indication for immediate event reporting.

[0044] Other embodiments include exposure functions (e.g., NEFs, SCEFs, or combinations thereof) and data management functions (e.g., UDMs) configured to perform operations corresponding to any of the exemplary methods described herein. Other embodiments include non-transitory, computer-readable media storing program instructions that, when executed by processing circuitry, configure such exposure functions or data management functions to perform operations corresponding to any of the exemplary methods described herein.

[0045] These and other embodiments disclosed herein can provide various advantages, benefits, and / or solutions to problems. For example, embodiments can reduce the amount of signaling required in dual-core networks (e.g., 4G and 5G) by a data management function (e.g., UDM) in one of the core networks informing an exposure function of whether a user subscription exists in a data management function (e.g., HSS) of the other core network, such that the exposure function only contacts the data management function of the other core network when the user subscription exists. For example, embodiments can reduce signaling performed by exposure functions (e.g., SCEF / NEF) in dual-core networks in relation to EE subscriptions related to UEs. Moreover, exposure functions need not be aware of whether a UE has a subscription to the first (e.g., 5G), the second (e.g., 4G), or both network types, since this ambiguity is managed by a data management function (e.g., UDM) associated with the first net worktype. Moreover, embodiments enable the data management function to determine whether the UE has a subscription to the second network type regardless of whether user subscription information is consolidated in a single database (e.g., UDR) or stored in separate databases (e.g., 5G-UDR and 4G-UDR). More generally, embodiments improve EE subscription management in dual -core networks, e.g., networks with 5GC and EPC.

[0046] These and other objects, features, and advantages of embodiments of the present disclosure will become apparent upon reading the following Detailed Description in view of the Drawings briefly described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 shows a high-level view of an exemplary LTE network architecture.

[0048] Figure 2 shows a high-level view of an exemplary 5G / NR network architecture.

[0049] Figures 3-5 show signaling diagrams of various procedures between an AS / SCS / AF, an SCEF / NF, a UDM in 5GC, and an HSS in EPC.

[0050] Figure 6 shows a signaling diagram of a procedure between an AS / SCS / AF, an SCEF / NF, a UDM in 5GC, and an HSS in EPC.

[0051] Figures 7-8 show signaling diagrams of procedures between an AS / SCS / AF, an SCEF / NF, a UDM in 5GC, and an HSS in EPC, according to various embodiments of the present disclosure.

[0052] Figure 9 is a flow diagram of an exemplary method (e.g., procedure) for an exposure function of a communication network, according to various embodiments of the present disclosure.

[0053] Figure 10 is a flow diagram of an exemplary method (e.g., procedure) for a first data management function of a communication network, according to various embodiments of the present disclosure.

[0054] Figure 11 is a flow diagram of an exemplary method (e.g., procedure) for a second data management function of a communication network, according to various embodiments of the present disclosure.

[0055] Figures 12-14 show signaling diagrams of procedures between an AS / SCS / AF, an SCEF / NF, a UDM in 5GC, and an HSS in EPC, according to various embodiments of the present disclosure.

[0056] Figure 15 is a flow diagram of an exemplary method (e.g., procedure) for an exposure function of a communication network, according to various embodiments of the present disclosure.

[0057] Figure 16 is a flow diagram of an exemplary method (e.g., procedure) for a first data management function of a communication network, according to various embodiments of the present disclosure.

[0058] Figure 17 shows a communication system according to various embodiments of the present disclosure.

[0059] Figure 18 shows a network node according to various embodiments of the present disclosure.

[0060] Figure 19 is a block diagram of a virtualization environment in which functions implemented by some embodiments of the present disclosure may be virtualized. DETAILED DESCRIPTION

[0061] 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 as examples to convey the scope of the subject matter to those skilled in the art.

[0062] In general, all terms used herein are to be interpreted according to their ordinary meaning to a person of ordinary skill in the relevant technical field, unless a different meaning is expressly defined and / or implied from the context of use. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise or clearly implied from the context of use. The operations of any methods and / or procedures disclosed herein do not have tobe performed in the exact order disclosed, unless an operation is explicitly described as following or preceding another operation and / or where it is implicit that an operation must follow or precede another operation. Any feature of any embodiment disclosed herein can apply to any other disclosed embodiment, as appropriate. Likewise, any advantage of any embodiment described herein can apply to any other disclosed embodiment, as appropriate.

[0063] Furthermore, the following terms are used throughout the description given below:

[0064] • Radio AccessNode: As used herein, a “radio access node” (or equivalently “radio network node,” “radio access network node,” or “RAN node”) can be any node in a radio access network (RAN) that operates to wirelessly transmit and / or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., gNB in a 3GPP 5G / NR network or an enhanced or eNB in a 3 GPP LTE network), base station distributed components (c.g, CU and DU), a high -power or macro base station, a low -power base station (c.g, micro, pico, femto, or home base station, or the like), an integrated access backhaul (IAB) node, a transmission point (TP), a transmission reception point (TRP), a remote radio unit (RRU or RRH), and a relay node.

[0065] • Core NetworkNode: As used herein, a “core network node” is any type of node in a core network. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a serving gateway (S GW), aPDN Gateway (P -GW), a Policy and Charging Rules Function (PCRF), an access and mobility management function (AMF), a session management function (SMF), a user plane function (UPF), a Charging Function (CHF), a Policy Control Function (PCF), an Authentication Server Function (AUSF), a location management function (LMF), or the like. • Wireless Device: As used herein, a “wireless device” (or “WD” for short) is any type of device that is capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other wireless devices. Communicating wirelessly can involve transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information through air. Unless otherwise noted, the term “wireless device” is used interchangeably herein with the term “user equipment” (or “UE” for short), with both of these terms having a different meaning than the term “network node”.

[0066] • Radio Node: As used herein, a “radio node” can be either a “radio access node” (or equivalent term) or a “wireless device.”

[0067] • NetworkNode: As used herein, a “network node” is any node that is either part of the radio access network (c.g, a radio access node or equivalent term) or of the core network (e.g., a core network node discussed above) of a cellular communications network. Functionally, a network node is equipment capable, configured, arranged, and / or operable to communicate directly or indirectly with a wireless device and / or with other network nodes or equipment in the cellular communications network, to enable and / or provide wireless access to the wireless device, and / or to perform other functions (e.g., administration) in the cellular communications network.

[0068] • Node: As used herein, the term “node” (without prefix) can be any type of node that can operate in or with a wireless network (including RAN and / or core network), including a radio access node (or equivalent term), core network node, or wireless device. However, the term “node” may be limited to a particular type (e.g., radio access node, IAB node) based on its specific characteristics in any given context.

[0069] The above definitions are not meant to be exclusive. In other words, various ones of the above terms may be explained and / or described elsewhere in the present disclosure using the same or similar terminology. Nevertheless, to the extent that such other explanations and / or descriptions conflict with the above definitions, the above definitions should control.

[0070] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3 GPP terminology or terminology similar to 3 GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3 GPP system and can be applied to any communication system that may benefit from them. Furthermore, although the term “cell” is used herein, it should be understood that (particularly with respect to 5G NR) beams may be used instead of cells and, as such, concepts described herein apply equally to both cells and beams.

[0071] Figure 2 shows an exemplary non-roaming reference architecture fora 5G network (200) including the following 3 GPP -defined NF s and service-based interfaces: • Application Function (AF, with Naf interface) interacts with the 5GC to provision information to the network operator and to subscribe to certain events happening in operator's network. An AF offers applications for which service is delivered in a different layer (i.e., transport layer) than the one in which the service has been requested (i.e., signaling layer), the control of flow resources according to what has been negotiated with the network. An AF communicates dynamic session information to PCF (via N5 interface), including description of media to be delivered by transport layer.

[0072] • Policy Control Function (PCF, with Npcf interface) supports unified policy framework to govern the network behavior, via providing PCC rules (e.g., on the treatment of each service data flow that is under PCC control) to the SMF via the N7 reference point. PCF provides policy control decisions and flow based charging control, including service data flow detection, gating, QoS, and flow-based charging (except credit management) towards the SMF. The PCF receives session and media related information from the AF and informs the AF of traffic (or user) plane events.

[0073] User Plane Function (UPF)- supports handling of user plane traffic based on the rules received from SMF, including packet inspection and different enforcement actions (e.g., event detection and reporting). UPFs communicate with the RAN (e.g., NG-RNA) via the N3 reference point, with SMFs (discussed below) via the N4 reference point, and with an external packet datanetwork (PDN) via theN6 reference point. The N9 reference point is for communication between two UPFs.

[0074] • Session Management Function (SMF, withNsmf interface) interacts with the decoupled traffic (or user) plane, including creating, updating, and removing Protocol Data Unit (PDU) sessions and managing session context with the User Plane Function (UPF), e.g., for event reporting. For example, SMF performs data flow detection (based on filter definitions included in PCC rules), online and offline charging interactions, and policy enforcement.

[0075] • Charging Function (CHF, with Nchf interface) is responsible for converged online charging and offline charging functionalities. It provides quota management (for online charging), re-authorization triggers, rating conditions, etc. and is notified about usage reports from the SMF. Quota management involves granting a specific number of units (e.g., bytes, seconds) for a service. CHF also interacts with billing systems.

[0076] Access and Mobility Management Function (AMF, with Namf interface) terminates the RAN CP interface and handles all mobility and connection management of UEs (similar to MME in EPC). AMFs communicate with UEs via the N1 reference point and with the RAN (e.g., NG-RAN) via the N2 reference point. • Network Exposure Function (NEF) with Nnef interface - acts as the entry point into operator's network, by securely exposing to AFs the network capabilities and events provided by 3GPP NFs and by providing ways for the AF to securely provide information to 3GPP network. For example, NEF provides a service that allows an AF to provision specific subscription data (e.g., expected UE behavior) for various UEs. In general, NEF provides services similar to services provided by SCEF in EPC.

[0077] • Network Repository Function (NRF) with Nnrf interface - provides service registration and discovery, enabling NFs to identify appropriate services available from other NFs.

[0078] • Network Slice Selection Function (NSSF) with Nnssf interface - a “network slice” is a logical partition of a 5G network that provides specific network capabilities and characteristics, e.g., in support of a particular service. A network slice instance is a set of NF instances and the required network resources (e.g., compute, storage, communication) that provide the capabilities and characteristics of the network slice. The NSSF enables other NFs (e.g., AMF) to identify a network slice instance that is appropriate for a UE’s desired service.

[0079] • Authentication Server Function (AUSF) with Nausf interface - based in a user’s home network (HPLMN), it performs user authentication and computes security key materials for various purposes.

[0080] • Network Data Analytics Function (NWD AF) with Nnwdaf interface - provides network analytics information (e.g., statistical information of past events and / or predictive information) to other NFs on a network slice instance level.

[0081] • Unified Data Management (UDM) function with Nudm interface - generation of 3GPP authentication credentials, user identification handling, access authorization based on subscription data, and other subscriber-related functions. The UDM obtains the subscription data (including authentication data) from the 5G unified data repository (5GS- UDR, with Nudr interface). 5GS-UDR supports storage and retrieval of policy data by the PCF, as well as storage and retrieval of application data by NEF. 5GS-UDRis also referred to as 5G-UDR.

[0082] The NRF allows every NF to discover the services offered by other NFs, and Data Storage Functions (DSF) allow every NF to store its context. In addition, the NEF provides exposure of capabilities and events of the 5GC to AFs within and outside of the 5GC. For example, NEF provides a service that allows an AF to provision specific subscription data e.g., expected UE behavior) for various UEs.

[0083] The services provided by the various NFs are composed of “service operations”, which are more granular divisions of the overall service functionality. The interactions between service consumers and producers can be of the type “request / response” or “subscribe / notify”. In the latter type, a service consumer NF (or equivalently, “consumer NF”) requests a service producer NF (or equivalently, “producer NF”) to establish a subscription for the service consumer NF to receive notifications from the service producer NF under conditions specified in this subscription.

[0084] Additionally, the LIE EPC can include a Service Capabilities Exposure Function (SCEF), which was introduced in Rel-13 to securely expose the services and capabilities provided by the 3GPP network interfaces. For example, the SCEF can expose services and capabilities provided by the HS S to application servers (AS) internal or external to the LIE network. As a more specific example, a machine-type communication (MTC) application hosted by an AS may communicate directly with the SCEF or via an intermediate a Services Capability Server (SCS), which communicates with MTC UEs in the LIE network. In this way, the SCEF provides access to network capabilities through homogenous network application programming interfaces (APIs), thereby abstracting services from the underlying 3GPP network interfaces and protocols.

[0085] As such, the SCEF provides similar functionality for 4G LIE networks as the NEF does for 5G networks. When an operator deploys both 4G and 5G networks, the SCEF and NEF functionality may be combined into a single entity, referred to herein as SCEF / NEF.

[0086] In networks that support both 4G and 5G, an AS / SCS or an AF may subscribe via SCEF / NEF forevent notifications related to a particular UE (also referred to as “event exposure” or EE). The SCEF / NEF sendsthe EE subscription request toUDM, to HSS, or to both. This choice depends on whether the particular UE has only 5G, only 4G, or both 5G and 4G subscriptions. This choice also depends on whether UDM-to-HSS interworking is supported in the network.

[0087] 3GPP TS 23.632 (vl8.2.0) clause 5.6 describes “common network exposure scenarios” in which an SCEF / NEF can configure monitoring events applicable to bothEPC and 5GC using only 5GC procedures towards UDM. In this case, the SCEF / NEF indicates that the monitoring event is also applicable to EPC together with the SCEF identity, i.e.„ that the event must be reported both by 5GC and EPC.

[0088] 3GPP TS 23.632 (vl8.2.0) clause 5.6.3 specifies that the status of some specific monitoring events that are detected locally at HS S and UDM are kept synchronized between UDM and HSS. For example, EE subscription of some events is managed by UDM without requiring that HSS receives the EE subscription request, but based on configuration in both HSS and UDM, the HSS keeps UDM informed about the status of these events. This synchronization applies to some specific monitoring events that are detected locally at the HSS and UDM, such as IMEI(SV) / PEI change, roaming status change, etc. Upon receiving a notification from HSS about such events taking place in EPS, the UDM can send a notification about such events to the combined SCEF+NEF using SBA procedures. 3GPP TS 23.632 (vl8.2.0) clause 5.6 describes “common network exposure scenarios” in which an SCEF / NEF can configure monitoring events applicable to bothEPC and 5GC using only 5GC procedures towards UDM. In this case, the SCEF / NEF indicates that the monitoring event is also applicable to EPC together with the SCEF identity, i.e.„ that the event must be reported both by 5GC and EPC.

[0089] 3GPP TS 23.632 (vl8.2.0) clause 5.6.3 specifies that the status of some specific monitoring events that are detected locally at HS S and UDM are kept synchronized between UDM and HSS. For example, EE subscription of some events is managed by UDM without requiring that HSS receives the EE subscription request, but based on configuration in both HSS and UDM, the HSS keeps UDM informed about the status of these events. This synchronization applies to some specific monitoring events that are detected locally at the HSS and UDM, such as IMEI(SV) / PEI change, roaming status change, etc. Upon receiving a notification from HSS about such events taking place in EPS, the UDM can send a notification about such events to the combined SCEF+NEF using SBA procedures.

[0090] Figure 3 shows a signaling diagram of a procedure between an AS / SCS / AF, an SCEF / NF, a UDM in 5GC, and an HSS in EPC. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, a UE of interest does not have a 4G subscription stored in HSS nor a 5G subscription stored in UDM.

[0091] In operation 1, the AS / SCS / AF sends an Nnef EventExposure Subscribe Request to the SCEF / NEF, for event notifications related to a UE. The message includes a UE identifier. In operation 2, the SCEF / NEF sends an Nudm EventExposure Subscribe Request to UDM for subscription to EE notifications for the UE. The SCEF / NEF also includes an “epcAppliedlnd” flag set to true in the request, which indicates to the UDM that it should also create a corresponding EE subscription in the HSS.

[0092] In this example, the UE does not have a 5G subscription stored in UDM. Accordingly, in operation 3, the UDM sends an Nnef EventExposure Subscribe Response indicating that USER NOT FOUND. However, this message only indicates that no 5G subscription for the UE exists in UDM; it does not indicate whether the UE has a 4G subscription stored in HSS. Given this uncertainty, the SCEF / NEF will need to send a further EE subscription request to HSS. In this example, this request will fail since the UE doesnot have a 4G subscription in HSS, causing the HSS to return an error message.

[0093] Figure 4 shows a signaling diagram of another procedure between an AS / SCS / AF, an SCEF / NF, a UDM in 5GC, and an HSS in EPC. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, aUE of interest has a 4G subscription stored in HSS but does not have a 5G subscription stored in UDM. In operation 1, the AS / SCS / AF sends an Nnef EventExposure Subscribe Request to the SCEF / NEF, for event notifications related to the UE. The message includes a UE identifier. In operation 2, the SCEF / NEF sends an Nudm EventExposure Subscribe Request to UDM for subscription to EE notifications for the UE. The SCEF / NEF also includes the “epcAppliedlnd” flag set to true in the request, indicating to the UDM that it should also create a corresponding EE subscription in the HSS.

[0094] In this example, the UE does not have a 5G subscription stored in UDM. Accordingly, in operation 3, the UDM sends an Nnef EventExposure Subscribe Response indicating that USER NOT FOUND. However, this message only indicates that no 5G subscription for the UE exists in UDM; it does not indicate whether the UE has a 4G subscription stored in HSS. Given this uncertainty, the SCEF / NEF will need to send a further EE subscription request to HSS. In this example, this request will succeed since the UE has a 4G subscription in HSS.

[0095] Note that the error message in operation 3 is the same in the two cases shown in Figures 3-4. As such, the SCEF / NEF is unable to distinguish between the two cases based on the error message.

[0096] Figure 5 shows a signaling diagram of another procedure between an AS / SCS / AF, an SCEF / NF, a UDM in 5GC, and an HSS in EPC. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, aUE of interest has a 5G subscription stored in UDM but does not have a 4G subscription stored in HSS.

[0097] Operations 1-2 are the same as corresponding operations in Figures 3-4. In operation 3, the UDM sends an Nnef EventExposure Subscribe Response indicating success for EE subscription in 5G but also including an “epcStatusInd=false” flag indicating that the EE subscription has not been successfully created in 4G.

[0098] Although the “epcStatusInd=false” indicates the 4G EE subscription was not created, it does not provide any information about the cause or reason, which may be other than no UE 4G subscription in HSS. For example, this flag is also set to “false” by UDM when interworking between UDM and HSS is not supported in the operation network. Given this uncertainty, the SCEF / NEF will need to send a further EE subscription request to HSS. In this example, this request will fail since the UE does not have a 4G subscription in HSS, causing the HSS to return an error message.

[0099] Embodiments of the present disclosure address these and other problems, difficulties, or issues by techniques for a first data management function (e.g., UDM) associated with a first network type (e.g., 5G) to provide specific information in an EE subscribe response to an exposure function’s (e.g., SCEF / NEF) subscribe request for EE notifications related to a particular UE, that enables the exposure function to determine whether UE subscription for a second network type (e.g., 4G) exists and, consequently, whether the exposure function should send (or refrain from sending) a second subscribe request for EE notifications related to the UE to a second data management function (e.g., HSS) associated with the second network type. Notably, the first data management function can provide such information in response to successful or unsuccessful subscriptions for EE notifications related to the UE with respect to the first network type.

[0100] Embodiments of the present disclosure can provide various advantages, benefits, and / or solutions to problems. For example, embodiments can reduce the amount of signaling required in dual-core networks (e.g., 4G and 5G) by a data management function (e.g., UDM) in one of the core networks informing an exposure function of whether a user subscription exists in a data management function (e.g., HSS) of the other core network, such that the exposure function only contactsthe data management function of the other core network when the user subscription exists. More generally, embodiments improve EE subscription management in dual -core networks, e.g., networks with 5GC and EPC.

[0101] Figure 6 shows a signaling diagram of a procedure between an AS / SCS / AF, an SCEF / NF, a UDM in 5GC, and an HSS in EPC. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, a UE of interest has a 4G subscription stored in HSS but does not have a 5G subscription stored in UDM.

[0102] In operation 1, the AS / SCS / AF sends an Nnef EventExposure Subscribe Request to the SCEF / NEF, for event notifications related to the UE. The message includes a UE identifier. In operation 2, the SCEF / NEF sends an Nudm EventExposure Subscribe Request to UDM for subscription to EE notifications for the UE. The SCEF / NEF also includes the “epcAppliedlnd” flag set to true in the request, indicating to the UDM that it should also create a corresponding EE subscription in the HSS.

[0103] In this example, the UE does not have a 5G subscription stored in UDM. Accordingly, in operation 3, the UDM determines that common exposure scenarios for 5GC / EPC are not applicable to this UE. In operation 4, the UDM sends an Nnef EventExposure Subscribe Response indicating that USER NOT FOUND, without attempting to create the EE subscription in HSS. However, this message only indicates that no 5G subscription for the UE exists in UDM; it does not indicate whether the UE has a 4G subscription stored in HSS. Given this uncertainty, the SCEF / NEF will need to send a further EE subscription request to HSS. In this example, this request will succeed since the UE has a 4G subscription in HSS, but it will require extra network signaling and processing resources to handle the additional request to HSS. Embodiments of the present disclosure address these and other problems, difficulties, or issues by techniques for a first data management function (e.g., UDM) associated with a first network type (e.g., 5G), upon receiving an EE subscribe request from an exposure function’s (e.g., SCEF / NEF) that also applies to a second network type (e.g., 4G), to create an EE subscription in the second network type even if the UE to which the EE subscribe request pertains does not have a subscription in the first network type. The first data management function can create such an EE subscription by sending a corresponding EE subscribe request to a second data management function (e.g., HSS) associated with the second network type. The first data management function can also inform the exposure function that the EE subscription was created in the second network type, but that the UE does not have a subscription to the first network type.

[0104] Embodiments of the present disclosure can provide various advantages, benefits, and / or solutions to problems. For example, embodiments can reduce signaling performed by exposure functions (e.g., SCEF / NEF) in dual-core networks (e.g., EPC / 5GC) in relation to EE subscriptions pertaining to UEs. Moreover, the exposure function does not need to be aware of whether a UE has a subscription to the first (e.g., 5G), the second (e.g., 4G), or both network types, since this ambiguity is managed by the first data management function (e.g., UDM) associated with the first network type. Moreover, embodiments avoid using legacy “Diameter” interfaces in the exposure domain while enabling the first data management function to determine whether the UE has a subscription to the second network type regardless of whether user subscription information is consolidated in a single database (e.g., UDR) or stored in separate databases (e.g., 5G-UDR and 4G-UDR). More generally, embodiments improve EE subscription management in dual-core networks, e.g., networks with 5GC and EPC.

[0105] Figure 7 shows a signaling diagram of a procedure between an AS / SCS / AF (710), an SCEF / NF (720), a UDM (730) in 5GC, and an HSS (740) in EPC, according to some embodiments of the present disclosure. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, a UE of interest has a 4G subscription stored in HSS but does not have a 5G subscription stored in UDM.

[0106] Operations 1-2 are similar to corresponding operations in Figure 6 described above. In operation 3, the UDM determines whether a consolidated 4G-UDR and 5G-UDR exists, such that both 4G and 5G subscription information in the consolidated UDR are accessible by UDM. This determination can be based on a configuration flag or indicator. If the flag indicates a consolidated UDR, then UDM queries this database for 4G and 5G subscriptions for the UE. In this case, the UDM determines that the UE has a 4G subscription but does not have a 5G subscription. On the other hand, if the flag indicates no consolidated UDR, the UDM can query the 5G- UDRto determine that the UE doesnot have a 5G subscription, but is unable to determine whether the UEhas a 4G subscription in a separate 4G-UDR. Thus, from the UDM’s perspective, there is ambiguity about whether the UE has a 4G subscription, even though such subscription exists.

[0107] In cases where the UE’s 4G subscription is confirmed (e.g., consolidated UDR) or remains ambiguous (e.g., separate 4G-UDR)from the UDM’s perspective, in operation 5 the UDM sends an Nhss EventExposure Subscribe Request to the HSS. In operation 6, the HSS sends to UDM an Nhss EventExposure Sub scribe Response including a flag epcStatusInd set to “true”, indicating that the requested EE subscription has been created in EPC. In operation 7, the UDM sends to SCEF / NEF an Nnef EventExposure Subscribe Response including a flag epcStatusInd set to “true” to indicate that EE subscription was successfully created in EPC and a second flag indicating that a 5G subscription for the UE does not exist.

[0108] Based on the message received in operation 7, the SCEF / NEF refrains from sending a further EE subscription request to the HSS, as done in conventional solutions.

[0109] The synchronization of status of monitoring events between HSS and UDM described in 3GPP TS 23.632 (vl8.2.0) clause 5.6.3 doesnot apply when the relevant UE does not have a 5G subscription. Conventionally, an EE subscription is discarded without attempting to create a 4G EE subscription for the UE in EPC as shown in Figure 6. Ifinstead a 4G EE subscription is created for the UE in EPC as shown in Figure 7, then some synchronization of events must be provided. Today, this synchronization of events applies to events locally detected in HSS / UDM, e.g., IMEI(SV) / PEI change, roaming status change, etc.

[0110] Figure 8 shows a signaling diagram of a procedure between an AS / SCS / AF (710), an SCEF / NF (720), a UDM (730) in 5GC, and an HSS (740) in EPC, according to other embodiments of the present disclosure. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, a UE of interest has a 4G subscription stored in HSS but does not have a 5G subscription stored in UDM.

[0111] Operations 1-2 are similar to operations 1-2 in Figure 7, except that in this case the requested EE subscription is event Type=EventX, which is subject to UDM-HSS synchronization. For example Event X can be ROAMING STATUS (indicating roaming status change) or SUPI PEI CHANGE (indicating IMEI(SV) / PEI change). In some embodiments, the message in operation 2 may include an “immediateReport” flag when the SCEF / NEF wants to receive a report for EventX in the responsive message, assuming such an immediate report is available and is support by the involved NFs.

[0112] Operations 3-4 are similar to operations 3-5 in Figure 7, with the UDM sending an Nhss EventExposure Subscribe Request for event Type=EventX to the HSS because the UE’s 4G subscription is confirmed (e.g., consolidated UDR) or remains ambiguous (e.g., separate 4G- UDR) from the UDM’s perspective. In case the message in operation 2 includes the “immediateReport” flag, the UDM includes this flag in the message sent in operation 4.

[0113] Since synchronization of event Type=EventX between HSS and UDM described in 3GPP TS 23.632 (vl8.2.0) clause 5.6.3 does not apply when a UE’s 5G subscription does not exist, UDM creating the EE subscription forEventX in HSS enables HSS to monitor and report those events on its own, without need for synchronization with UDM. 3GPP TS 29.563 (vl 8.2.0) defines the interworking interface between UDM and HSS, which includes the Nhss EventExposure service (also referred to as “Nhss_EE”). This service includes an “EventType” data type, which is defined in clause 6.4.6.3.3 of this document. Note that the current definition does not include the event types that are subject to UDM-HSS synchronization as specified in 3GPP TS 23.632 (vl 8.2.0) clause 5.6.3. Accordingly, in some embodiments, the definition in 3GPP TS 29.563 (vl8.2.0) clause 6.4.6.3.3 can be expanded to include such event types. This is illustrated in the table below where underline indicates additions.

[0114]

[0115] In operation 5, the HSS sends to UDM an Nhss EventExposure Subscribe Response including a flag epcStatusInd set to “true”, indicating that the requested EE subscription has been created in EPC. In some embodiments, the HSS may include a monitoring report for EventX, e.g., in case an immediate report was required in operation 5 and is currently available.

[0116] In operation 6, the UDM sends to SCEF / NEF an Nnef EventExposure Subscribe Response including a flag epcStatusInd set to “true” to indicate that EE subscription was successfully created in EPC and a second flag indicating that a 5G subscription for the UE does not exist. If the UDM received a monitoring report from HSS in operation 5, the UDM also includes this monitoring report in the response sent to SCEF / NEF in operation 6. Based on the message receive in operation 6, the SCEF / NEF refrains from sending a further EE subscription request to the HSS, as done in conventional solutions.

[0117] In operation 7, the HSS detects an occurrence of EventX corresponding to the EE subscription established earlier. In operation 8, the HSS sendstheUDM anNhss_EventExposure_ Notification Request including a monitoring report for EventX, as well as including the flag epcStatusInd set to “true” to indicate that the EE subscription is in EPC . In operation 9, the UDM sends SCEF / NEF an Nudm EventExposure Notification Request including the content received from the HSS in operation 8.

[0118] The embodiments described above can be further illustrated with reference to Figures 9- 11, which show exemplary methods (e.g., procedures) performed by an exposure function, a first data management function, and a second data management function, respectively. In other words, various features of operations described below correspond to various embodiments described above. These exemplary method scan be used cooperatively to provide various exemplary benefits and / or advantages. Although Figures 9-11 show specific blocks in a particular order, the operations of the respective methods can be performed in different orders than shown and can be combined and / or divided into blocks having different functionality than shown. Optional blocks or operations are indicated by dashed lines.

[0119] In particular, Figure 9 shows a flow diagram of an exemplary method (e.g., procedure) for an exposure function configured to operate in a communication network that includes a first core network and a second core network, according to various embodiments of the present disclosure . For example, the exemplary method can be performed by an NEF, an SCEF, or a combination thereof, such as described elsewhere herein.

[0120] The exemplary method includes operations of block 920, where the exposure function can send, to a first data management function of the first core network, a first event exposure (EE) subscription request for notifications from the first core network related to a UE. The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE. The exemplary method also includes the operations of block 930, where the exposure function can receive, from the first data management function, a first EE subscription response including the following:

[0121] • a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, and

[0122] • a second indication that a subscription for the UE does not exist in the first core network. The exemplary method also includes the operations of block 940, where based on the first indication, the exposure function can selectively send to the second data management function a second EE subscription request for notifications from the second core network related to the UE

[0123] In some embodiments, the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network. In some of these embodiments, the first EE subscription request includes an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required. In some variants of these embodiments, the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event.

[0124] In some variants of these embodiments, the first EE subscription request also includes an indication for immediate event reporting. When the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network, the first EE subscription response also includes a monitoring report for the first event, in accordance with the indication for immediate event reporting. Figure 8 shows an example of these embodiments.

[0125] In some variants of these embodiments, the exemplary method can also include the operations of block 950, where when the first indication in block 930 indicates that an EE subscription for notifications related to the UE was successfully created in the second core network, the exposure function can subsequently receive from the first data management function an EE notification including the following:

[0126] • a further first indication that an EE subscription for notifications related to the UE was successfully created in the second core network, and

[0127] • a monitoring report from the second core network for the first event.

[0128] Figure 8 shows an example of these embodiments.

[0129] In some embodiments, the exemplary method can also include the operations of block 910, where the exposure function can receive, from an application function (AF) or application server (AS) associated with the communication network, an EE subscription request for notifications from the communication network related to the UE. In such case, sending the first EE subscription request in block 920 is responsive to receiving the EE subscription request from the AF or the AS in block 910.

[0130] In some embodiments, selectively sending the second EE subscription request to the second data management function in block 940 includes the following operations, labelled with corresponding sub-block numbers:

[0131] • (941) sending the second EE subscription request to the second data management function when the first indication indicates that no EE subscription for notifications related to the UE was successfully created in the second core network; and

[0132] • (942) refraining from sending the second EE subscription request to the second data management function when the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network.

[0133] In some embodiments, the second indication is 5G_USER_DOES_NOT_EXIST application error code. In some embodiments, the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the second core network based on a USER NOT FOUND application error code.

[0134] In some embodiments, the first core network is a 5G core network (5GC), the second core network is a 4G evolved packet core network (EPC), the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF), the first data management function is a unified data management (UDM) function, and the second data management function is a home subscriber server (HSS).

[0135] In addition, Figure 10 shows a flow diagram of an exemplary method (e.g., procedure) for a first data management function configured to operate in a first core network (e.g., 5GC) of a communication network that also includes a second core network (e.g., EPC), according to various embodiments of the present disclosure. For example, the exemplary method can be performed by a UDM such as described elsewhere herein.

[0136] The exemplary method can include the operations of block 1010, where the first data management function can receive, from an exposure function of the communication network, a first EE subscription request for notifications from the first core network related to a UE. The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE. The exemplary method also includes the operations of block 1020, where the first data management function can determine that a subscription for the UE does not exist in the first core network. The exemplary method also includes the operations of block 1030, where the first data management function can determine the following:

[0137] • whether user subscription data for the second core network is accessible to the first data management function, and

[0138] • if determined to be accessible, whether the user subscription data for the second core network includes a subscription for the UE;

[0139] The exemplary method also includes the operations of block 1040, where the first data management function can attempt to create an EE subscription for notifications from the second core network related to the UE, in accordance with the first EE subscription request, in response to each of the following conditions:

[0140] • the user subscription data for the second core network includes a subscription for the UE; and

[0141] • the first data management function is unable to determine whether the user subscription data for the second core network includes a subscription for the UE. The exemplary method also includes the operations of block 1050, where the first data management function can send, to the exposure function, a first EE subscription response including the following:

[0142] • a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, and

[0143] • a second indication that a subscription for the UE does not exist in the first core network.

[0144] In some embodiments, attempting to create an EE subscription for notifications from the second core network related to theUE in block 1040 includes the following operations, labelled with corresponding sub-block numbers:

[0145] • (1041) sending, to a second data management function of the second core network, a second EE subscription request for notifications from the second core network related to the UE; and

[0146] • (1042) receiving from the second data management function a second EE subscription response including the first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network.

[0147] The first EE subscription response is based on the second EE subscription response.

[0148] In some of these embodiments, the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network. In some variants of these embodiments, the first and second EE subscription requests include an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required. In some further variants, the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event.

[0149] In some further variants, the first EE subscription request also includes an indication for immediate event reporting. When the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network, the first EE subscription response also includes a monitoring report for the first event, in accordance with the indication for immediate event reporting. Figure 8 shows an example of these variants.

[0150] In some further variants, the exemplary method can also include the operations of blocks 1060-1070. In block 1060, when the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network, the first data management function can subsequently receiving from the second data management function a first EE notification including the following:

[0151] • a further first indication that an EE subscription for notifications related to the UE was successfully created in the second core network, and

[0152] • a monitoring report for the first event; and In block 770, the first data management function can send to the exposure function a second EE notification including the further first indication and the monitoring report.

[0153] In some embodiments, the second indication is 5G_USER_DOES_NOT_EXIST application error code. In some embedments, the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the second core network based on a USER NOT FOUND application error code.

[0154] In some embodiments, determining whether user subscription data for the second core network is accessible to the first data management function in block 1030 includes the operations of sub-block 1031, where the first data management function can determine, based on a configuration flag, whether a user subscription repository for the second core network is consolidated with a user subscription repository for the first core network, which is accessible to the first data management function.

[0155] In some embodiments, the first core network is a 5G core network (5GC), the second core network is a 4G evolved packet core network (EPC), the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF), and the first data management function is a unified data management (UDM) function.

[0156] In addition, Figure 11 shows a flow diagram of an exemplary method (e.g., procedure) for a second data management function configured to operate in a second core network (e.g., EPC) of a communication network that also includes a first core network (e.g., 5GC), according to various embodiments of the present disclosure. For example, the exemplary method can be performed by an HSS such as described elsewhere herein.

[0157] The exemplary method includes the operations of block 1110, where the second data management function can receive, from a first data management function of the first core network, a second EE subscription request for notifications from the second core network related to a UE. A subscription for the UE does not exist in the first core network. The exemplary method also includes the operations of block 1130, where the second data management function can attempt to create an EE subscription for notifications from the second core network related to the UE, in accordance with the second EE subscription request. The exemplary method can also include the operations of block 1150, where the second data management function can send to the first data management function a second EE subscription response including a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network.

[0158] In some embodiments, the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network. In some of these embodiments, the second EE subscription request includes an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required. In some variants of these embodiments, the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event.

[0159] In some variants of these embodiments, the second EE subscription request also includes an indication for immediate event reporting and the exemplary method also includes the operations of block 1140, where the second data management function can detect the first event after an EE subscription for notifications related to the UE was successfully created in the second core network. In such case, the second EE subscription response also includes a monitoring report for the detected first event, in accordance with the indication for immediate event reporting. Figure 8 shows an example of these variants.

[0160] In some variants of these embodiments, the exemplary method also includes the following operations, labelled with corresponding block numbers:

[0161] • (1160) detecting the first event after sending the second EE subscription response including a first indication that an EE subscription for notifications related to the UE was successfully created in the second core network; and

[0162] • (1170) sending to the first data management function a first EE notification including the following: a further first indication that an EE subscription for notifications related to the UE was successfully created in the second core network, and a monitoring report for the detected first event.

[0163] In some embodiments, the exemplary method can also include the operations of block 1120, where the second data management function can determine whether a subscription for the UE exists in the second core network. In such embodiments, attempting to create the EE subscription for notifications from the second core network in block 1130 is based on determining in block 1120 that a subscription for the UE exists in the second core network. In some of these embodiments, when it is determined that a subscription for the UE does not exist in the second core network, the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the second core network based on a USER NOT FOUND application error code.

[0164] In some embodiments, the first data management function is unable to determine whether user subscription data for the second core network includes a subscription for the UE. In other embodiments, user subscription data for the second core network is accessible to the first data management function and includes a subscription for the UE.

[0165] In some embodiments, the first core network is a 5G core network (5GC), the second core network is a 4G evolved packet core network (EPC), the first data management function is a unified data management (UDM) function, and the second data management function is a home subscriber server (HSS).

[0166] Figure 12 shows a signaling diagram of a procedure between an AS / SCS / AF (1210), an SCEF / NF (1220), a UDM (1230) in 5GC, and an HSS (1240) in EPC, according to some embodiments of the present disclosure. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, a UE of interest has no 4G subscription stored in HSS and has no 5G subscription stored in UDM.

[0167] Operations 1-2 are similar to corresponding operations in Figures 3-5 described above. In operation 3, the UDM sends an Nnef EventExposure Sub scribe Response with information indicating that neither 4G nor 5G subscriptions exist for this UE. In some embodiments, this information may be included separate from the indication UE NOT FOUND, e.g., by an application error code such as 4G_5G_USER_DOES_NOT_EXIST. In some embodiments, this information may be included as part of a ProblemD etails field, which would allow for backwaid compatibility with existing fields. In other embodiments, this information can be part of a new error field added to the response message. In other embodiments, this information can be indicated by the existing USER NOT FOUND application error, which can be clarified or expanded to indicate this new information.

[0168] Based on the response in operation 3, the SCEF / NEF knows that the UE has no 4G subscription in HSS, so refrains from sending a second subscribe request to HSS. In operation 4, SCEF / NEF sends an Nnef_EventExposure_Subscribe Response to the AS / SCS / AF with information indicating that neither 4G nor 5G subscriptions exist for this UE. For example, this information can be indicated by an application error code such as 4G_5G_USER_DOES_NOT_ EXIST, which can be added to 3GPP TS 29.122 (vl8.2.0) Table 5.3.5.3-1 such as shown below. This table defines application errors defined for the MonitoringEvent application programming interface (API). Alternately, existing application errors defined in this table can be clarified and / or redefined to indicate that neither 4G nor 5G subscriptions exist for this UE.

[0169]

[0170] Figure 13 shows a signaling diagram of another procedure between an AS / SCS / AF (1210), an SCEF / NF (1220), a UDM (1230) in 5GC, and an HSS (1240) in EPC, according to other embodiments of the present disclosure. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, a UE of interest has a 4G subscription stored in HSS but does not have a 5G subscription stored in UDM.

[0171] Operations 1-2 are similar to corresponding operations in Figures 3-5 described above. In operation 3, the UDM sends an Nnef EventExposure Sub scribe Response with information indicating that a 4G subscriptions exists for this UE but that a 5G subscription does not exist for this UE.

[0172] In some embodiments, this information may be indicated by respective application error codes such as 4G USER EXISTS and 5G_USER_DOES_NOT_EXIST. In other embodiments, this information may be indicated only by application error code 4G USER EXISTS, with the indication that a 5G subscription does not exist for this UE being implicit. In other embodiments, when only the application error code 4G USER EXISTS is included, this indicates that the UDM is unable to identify whether a 5G subscription exists for this UE.

[0173] In other embodiments, this information may be indicated by the existing application error code UE NOT FOUND, which is interpreted in light of the 4G_5G_USER_ DOES NOT EXIST application error code discussed above in relation to Figure 12. Put differently, since 4G_5G_USER_DOES_NOT_EXIST is used to indicate that neither 4G nor 5G subscriptions exist for this UE, the existing USER NOT FOUND indicates the different condition that a 4G subscription exists but a 5G subscription does not exist.

[0174] In some embodiments, this information may be included as part of a ProblemDetails field, which would allow for backward compatibility with existing fields. In other embodiments, this information can be part of a new error field added to the response message. In other embodiments, this information can be indicated by the existing USER NOT FOUND application error, which can be clarified or expanded to indicate this new information.

[0175] Based on the response in operation 3, the SCEF / NEF knows that the UE has a 4G subscription in HSS, so it can send a second subscribe request for EE notifications to HSS.

[0176] Figure 14 shows a signaling diagram of another procedure between an AS / SCS / AF (1210), an SCEF / NF (1220), a UDM (1230) in 5GC, and an HSS (1240) in EPC, according to other embodiments of the present disclosure. The 5GC and EPC are part of the same operator network, e.g., a “dual core” network. In this example, a UE of interest has a 5G subscription stored in UDM but does not have a 4G subscription stored in HSS.

[0177] Operations 1-2 are similar to corresponding operations in Figures 3-5 described above. In operation 3, the UDM sends an Nnef EventExposure Subscribe Response indicating success for EE subscription in 5G, an “epcStatusInd=false” flag indicating that the EE subscription was not successfully created in 4G, and information indicating that a 4G subscription does not exist for this UE.

[0178] Based on the response in operation 3, the SCEF / NEF knows that the UE has no 4G subscription in HSS, so refrains from sending a second subscribe request to HSS. In some embodiments, the SCEF / NEF can send an Nnef EventExposure Sub scribe Response to the AS / SCS / AF with information indicating that a 4G subscription does not exist for this UE.

[0179] The embodiments described above can be further illustrated with reference to Figures 15- 16, which show exemplary methods (e.g., procedures) performed by an exposure function and a first data management function, respectively. In other words, various features of operations described below correspond to various embodiments described above. These exemplary methods can be used cooperatively to provide various exemplary benefits and / or advantages. Although Figures 15-16 show specific blocks in a particular order, the operations of the respective methods can be performed in different orders than shown and can be combined and / or divided into blocks having different functionality than shown. Optional blocks or operations are indicated by dashed lines.

[0180] In particular, Figure 15 shows a flow diagram of an exemplary method (e.g., procedure) for an exposure function configured to operate in a communication network that includes a first core network and a second core network, according to various embodiments of the present disclosure. For example, the exemplary method can be performed by an NEF, an SCEF, or a combination thereof, such as described elsewhere herein.

[0181] The exemplary method includes the operations of block 1520, where the exposure function can send, to a first data management function of the first core network, a first event exposure (EE) subscription request for notifications from the first core network related to a UE. The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE. The exemplary method also includes the operations of block 1530, where the exposure function can receive, from the first data management function, a first EE subscription response including the following:

[0182] • a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and

[0183] • a second indication of whether a subscription for the UE exists in the second core network; and

[0184] The exemplary method also includes the operations of block 1540, where based on the second indication, the exposure function can selectively send to the second data management function a second EE subscription request for notifications from the second core network related to the UE.

[0185] In some embodiments, when the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the first core network, the first EE subscription response also includes a further second indication of whether a subscription for the UE exists in the first core network. In some of these embodiments, when the further second indication indicates that a subscription of theUE does not exist in the first core network, one of the following applies:

[0186] • the second indication and the further second indication are a single indication that no subscription for the UE exists in the first core network or the second core network (e.g., as in Figure 12); or

[0187] • the second indication and the further second indication are separate indications.

[0188] In some of these embodiments, the exemplary method can also include the operations of block 1510, where the exposure function can receive, from an application function (AF) or application server (AS) associated with the communication network, an EE subscription request for notifications from the communication network related to the UE. In such case, sending the first EE subscription request in block 1520 is responsive to receiving the EE subscription request from the AF or the AS in block 1510.

[0189] In some variants of these embodiments, the exemplary method can also include the operations of block 1550, where when the second indication indicates that a subscription of the UE does not exist in the second core network and the further second indication indicates that a subscription of the UE does not exist in the first core network, the exposure function can send to the AF or the AS an EE subscription response indicating that a subscription for the UE does not exist in the communication network. In some embodiments, selectively sending the second EE subscription request to the second data management function in block 1540 includes the following operations, labelled with corresponding sub-block numbers:

[0190] • (1541) sending the second EE subscription request to the second data management function when the second indication indicates that a subscription for the UE exists in the second core network; and

[0191] • (1542) refraining from sending the second EE subscription request to the second data management function when the second indication indicates that no subscription for the UE exists in the second core network.

[0192] In some embodiments, the first core network is a 5G core network (5GC), the second core network is a 4G evolved packet core network (EPC), the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF), the first data management function is a unified data management (UDM) function, and the second data management function is a home subscriber server (HSS).

[0193] In some of these embodiments, the second indication is one of the following application error codes: 4G_5G_USER_DOES_NOT_EXIST (e.g., as in Figure 12), 4G USER EXISTS (e.g., as in Figure 13), or4G_USER_DOES_NOT_EXIST (e.g., as in Figure 14). In some of these embodiments, the first indication that an EE subscription for notifications related to the UE was not successfully created in the first core network is a UE NOT FOUND application error code.

[0194] In addition, Figure 16 shows a flow diagram of an exemplary method (e.g., procedure) for a first data management function configured to operate in a first core network (e.g., 5GC) of a communication network that also includes a second core network (e.g., EPC), according to various embodiments of the present disclosure. For example, the exemplary method can be performed by a UDM such as described elsewhere herein.

[0195] The exemplary method includes the operations of block 1610, where the first data management function can receive, from an exposure function of the communication network, a first EE subscription request for notifications from the first core network related to a UE. The first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE. The exemplary method also includes the operations of block 1620, where the first data management function can determine whether a subscription for the UE exists in the first core network and whether a subscription for the UE exists in the second core network .The exemplary method also includes the operations of block 1630, where when it is determined that a subscription for the UE exists in the first core network, the first data management function can attempt to create an EE subscription for notifications from the first core network related to the UE, in accordance with the first EE subscription request. The exemplary method also includes the operations of block 1640, where the first data management function can send, to the exposure function, a first EE subscription response including the following:

[0196] • a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and

[0197] • a second indication of whether a subscription for the UE exists in the second core network.

[0198] In some embodiments, when the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the first core network, the first EE subscription response also includes a further second indication of whether a subscription for the UE exists in the first core network. In some of these embodiments, when the further second indication indicates that a subscription of theUE does not exist in the first core network, one of the following applies:

[0199] • the second indication and the further second indication are a single indication that no subscription for the UE exists in the first core network or the second core network (e.g., as in Figure 12); or

[0200] • the second indication and the further second indication are separate indications.

[0201] In some embodiments, the first core network is a 5G core network (5GC), the second core network is a 4G evolved packet core network (EPC), the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF), the first data management function is a unified data management (UDM) function, and the second data management function is a home subscriber server (HSS).

[0202] In some of these embodiments, the second indication is one of the following application error codes: 4G_5G_USER_DOES_NOT_EXIST (e.g, as in Figure 12), 4G USER EXISTS (e.g, as in Figure 13), or4G_USER_DOES_NOT_EXIST(e.g, as in Figure 14). In some of these embodiments, the first indication that an EE subscription for notifications related to the UE was not successfully created in the first core network is a UE NOT FOUND application error code.

[0203] In the context of Figures 15-16, it should be understood that although the first data management function (e.g, UDM) is of, associated with, or included in the first core network (e.g, 5GC), that does not restrict it from interacting with the second core network (e.g, EPC), such as via the second data management function (e.g, HSS). Likewise, it should be understood that although the second data management function is of, associated with, or included in the second core network, that does not restrict it from interacting with the first core network, such as via the first data management function. Although various embodiments are described herein above in terms of methods, apparatus, devices, computer-readable medium and receivers, the person of ordinary skill will readily comprehend that such methods can be embodied by various combinations of hardware and software in various systems, communication devices, computing devices, control devices, apparatuses, non-transitory computer-readable media, etc.

[0204] Figure 17 shows an example of a communication system 1700 in accordance with some embodiments. In this example, communication system 1700 includes a telecommunication network 1702 that includes an access network 1704 (e.g., RAN) and a core network 1706, which includes one or more core networknodes 1708. Access network 1704 includes one or more access network nodes, such as network nodes 1710a-b (one or more of which may be generally referred to as network nodes 1710), or any other similar 3GPP access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, telecommunication network 1702 includes one or more Open -RAN (ORAN) network nodes. An ORAN network node is a node in telecommunication network 1702 that supports an ORAN specification (e.g., a specification published by the O -RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in telecommunication network 1702, including one or more network nodes 1710 and / or core network nodes 1708.

[0205] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU- CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non -real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or anon-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O -Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the O-RAN Alliance or comparable technologies. Network nodes 1710 facilitate direct or indirect connection of UEs, such as by connecting UEs 1712a-d (one or more of which may be generally referred to as UEs 1712) to core network 1706 over one or more wireless connections.

[0206] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, communication system 1700 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. Communication system 1700 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0207] UEs 1712 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with network nodes 1710 and other communication devices. Similarly, network nodes 1710 are arranged, capable, configured, and / or operable to communicate directly or indirectly with UEs 1712 and / or with other network nodes or equipment in telecommunication network 1702 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in telecommunication network 1702.

[0208] In the depicted example, core network 1706 connects network nodes 1710 to one or more hosts, such as host 1716. These connections may be direct or indirect via one ormore intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. Core network 1706 includes one or more core network nodes (e.g., 1708) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of core network node 1708. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0209] Host 1716 may be under the ownership or control of a service provider other than an operator or provider of access network 1704 and / or telecommunication network 1702, and may be operated by the service provider or on behalf of the service provider. Host 1716 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0210] As a whole, communication system 1700 of Figure 17 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z -Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0211] In some examples, telecommunication network 1702 is a cellular network that implements 3GPP standardized features. Accordingly, telecommunication network 1702 may support network slicing to provide different logical networks to different devices that are connected to telecommunication network 1702. For example, telecommunication network 1702 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.

[0212] In some examples, UEs 1712 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to access network 1704 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from access network 1704. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi -radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0213] In the example, hub 1714 communicates with access network 1704 to facilitate indirect communication between one or more UEs (e.g., UE 1712c and / or 1712d) and network nodes (e.g., network node 1710b). In some examples, hub 1714 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, hub 1714 may be a broadband router enabling access to core network 1706 for the UEs. As another example, hub 1714 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 1710, or by executable code, script, process, or other instructions in hub 1714. As another example, hub 1714 may be a datacollector that acts as temporary storage for UE dataand, in some embodiments, may perform analysis or other processing of the data. As another example, hub 1714 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, hub 1714 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which hub 1714 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, hub 1714 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0214] Hub 1714 may have a constant / persistent or intermittent connection to network node 1710b. Hub 1714 may also allow for a different communication scheme and / or schedule between hub 1714 and UEs (e.g., UE 1712c and / or 1712d), and between hub 1714 and core network 1706. In other examples, hub 1714 is connected to core network 1706 and / or one or more UEs via a wired connection. Moreover, hub 1714 may be configured to connect to an M2M service provider over access network 1704 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with network nodes 1710 while still connected via hub 1714 via a wired or wireless connection. In some embodiments, hub 1714 may be a dedicated hub - that is, a hub whose primary function is to route communications to / fromtheUEsfrom / to network node l710b. In other embodiments, hub 1714 may be anon-dedicated hub -that is, a device which is capable of operating to route communications between the UEs and network node 1710b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0215] Figure 18 shows a network node 1800 in accordance with some embodiments. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (e.g., radio base stations, NodeBs, eNBs, gNBs), and O-RAN nodes or components of an O-RAN node (e.g, O-RU, O-DU, O-CU).

[0216] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0217] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSRBSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi -cell / multi cast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0218] Network node 1800 includes a processing circuitry 1802, a memory 1804, a communication interface 1806, and a power source 1808. Network node 1800 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which network node 1800 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, network node 1800 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1804 for different RATs) and some components may be reused (e.g., a same antenna 1810 may be shared by different RATs). Network node 1800 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1800, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z- wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1800.

[0219] The processing circuitry 1802 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1800 components, such as memory 1804, to provide network node 1800 functionality.

[0220] In some embodiments, the processing circuitry 1802 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1802 includes radio frequency (RF) transceiver circuitry 1812 and / or baseband processing circuitry 1814. In some embodiments, RF transceiver circuitry 1812 and / or baseband processing circuitry 1814 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1812 and / or baseband processing circuitry 1814 may be on the same chip or set of chips, boards, or units.

[0221] Memory 1804 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid -state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1802. Memory 1804 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions (collected denoted computer program 1804a, which may be in the form of a computer program product) capable of being executed by the processing circuitry 1802 and utilized by networknode 1800. Memory 1804 may be used to store any calculations made by the processing circuitry 1802 and / or any datareceived via communication interface 1806. In some embodiments, the processing circuitry 1802 and memory 1804 is integrated.

[0222] Communication interface 1806 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, communication interface 1806 comprises port(s) / terminal(s) 1816 to send and receive data, for example to and from a network over a wired connection. Communication interface 1806 also includes radio frontend circuitry 1818 that may be coupled to, or in certain embodiments a part of, antenna 1810. Radio front-end circuitry 1818 comprises filters 1820 and amplifiers 1822. Radio front-end circuitry 1818 may be connected to an antenna 1810 and processing circuitry 1802. The radio front -end circuitry may be configured to condition signals communicated between antenna 1810 and processing circuitry 1802. Radio front -end circuitry 1818 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. Radio front -end circuitry 1818 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1820 and / or amplifiers 1822. The radio signal may then be transmitted via antenna 1810. Similarly, when receiving data, antenna 1810 may collect radio signals which are then converted into digital data by radio front -end circuitry 1818. The digital data may be passed to the processing circuitry 1802. In other embodiments, the communication interface may comprise different components and / or different combinations of components. In certain alternative embodiments, network node 1800 does not include separate radio front -end circuitry 1818, instead, the processing circuitry 1802 includes radio front -end circuitry and is connected to antenna 1810. Similarly, in some embodiments, all or some of RF transceiver circuitry 1812 is part of communication interface 1806. In still other embodiments, communication interface 1806 includes one or more ports or terminals 1816, radio front-end circuitry 1818, and RF transceiver circuitry 1812, as part of a radio unit (not shown), and communication interface 1806 communicates with baseband processing circuitry 1814, which is part of a digital unit (not shown).

[0223] Antenna 1810 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. Antenna 1810 may be coupled to radio front-end circuitry 1818 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, antenna 1810 is separate from network node 1800 and connectable to network node 1800 through an interface or port.

[0224] Antenna 1810, communication interface 1806, and / or the processing circuitry 1802 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, antenna 1810, communication interface 1806, and / or the processing circuitry 1802 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0225] Power source 1808 provides power to the various components of network node 1800 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). Power source 1808 may further comprise, or be coupled to, power management circuitry to supply the components of network node 1800 with power for performing the functionality described herein. For example, network node 1800 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of power source 1808. As a further example, power source 1808 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0226] Embodiments of network node 1800 may include additional components beyond those shown in Figure 18 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, network node 1800 may include user interface equipment to allow input of information into network node 1800 and to allow output of information from network node 1800. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for network node 1800.

[0227] Figure 19 is a block diagram illustrating a virtualization environment 1900 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1900 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1900 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

[0228] Applications 1902 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 1900 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0229] Hardware 1904 includes processing circuitry, memory that stores software and / or instructions (collected denoted computer program 1904a, which may be in the form of a computer program product) executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1906 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1908a-b (one or more of which may be generally referred to as VMs 1908), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. Virtualization layer 1906 may present a virtual operating platform that appears like networking hardware to the VMs 1908.

[0230] VMs 1908 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1906. Different embodiments of the instance of a virtual appliance 1902 may be implemented on one or more of VMs 1908, and the implementations may be in different forms. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0231] In the context of NFV, each VM 1908 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non -virtualized machine. Each VM 1908, and that part of hardware 1904 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1908 on top of the hardware 1904 and corresponds to the application 1902.

[0232] Hardware 1904 may be implemented in a standalone network node with generic or specific components. Hardware 1904 may implement some functions via virtualization. Alternatively, hardware 1904 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration function 1910, which, among others, oversees lifecycle management of applications 1902. In some embodiments, hardware 1904 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1912 which may alternatively be used for communication between hardware nodes and radio units.

[0233] The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures that, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the spirit and scope of the disclosure. Various exemplary embodiments can be used together with one another, as well as interchangeably therewith, as should be understood by those having ordinary skill in the art.

[0234] The term unit, as used herein, can have conventional meaning in the field of electronics, electrical devices and / or electronic devices and can include, for example, electrical and / or electronic circuitry, devices, modules, processors, memories, logic solid state and / or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and / or displaying functions, and so on, as such as those that are described herein.

[0235] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for performing one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0236] As described herein, device and / or apparatus can be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of a device or apparatus, instead of being hardware implemented, be implemented as a software module such as a computer program or a computer program product comprising executable software code portions for execution or being run on a processor. Furthermore, functionality of a device or apparatus can be implemented by any combination of hardware and software. A device or apparatus can also be regarded as an assembly of multiple devices and / or apparatuses, whether functionally in cooperation with or independently of each other. Moreover, devices and apparatuses can be implemented in a distributed fashion throughout a system, so long as the functionality of the device or apparatus is preserved. Such and similar principles are considered as known to a skilled person.

[0237] 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.

[0238] In addition, certain terms used in the present disclosure, including the specification and drawings, can be used synonymously in certain instances (e.g., “data” and “information”). It should be understood, that although these terms (and / or other terms that can be synonymous to one another) can be used synonymously herein, there can be instances when such words can be intended to not be used synonymously.

[0239] The techniques and apparatus described herein include, but are not limited to, the following enumerated examples:

[0240] Al . A method for an exposure function configured to operate in a communication network that includes a first core network and a second core network, the method comprising: sending, to a first data management function of the first core network, a first event exposure (EE) subscription request for notifications from the first core network related to a user equipment (UE), wherein the first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE; receiving, from the first data management function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and a second indication of whether a subscription for the UE exists in the second core network; and based on the second indication, selectively sending to the second data management function a second EE subscription request for notifications from the second core network related to the UE.

[0241] A2. The method of embodiment Al, wherein when the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the first core network, the first EE subscription response also includes a further second indication of whether a subscription for the UE exists in the first core network.

[0242] A3. The method of embodiment A2, wherein when the further second indication indicates that a subscription of the UE does not exist in the first core network, one of the following applies: the second indication and the further second indication are a single indication that no subscription for the UE exists in the first core network or the second core network; or the second indication and the further second indication are separate indications. A4. The method of any of embodiments A2-A3, further comprising receiving, from an application function (AF) or application server (AS) associated with the communication network, an EE subscription request for notifications from the communication network related to the UE, wherein sending the first EE subscription request is responsive to receiving the EE subscription request from the AF or the AS.

[0243] A5. The method of embodiment A4, further comprising, when the second indication indicates that a subscription of the UE does not exist in the second core network and the further second indication indicates that a subscription of the UE does not exist in the first core network, sending to the AF or the AS an EE subscription response indicating that a subscription for the UE does not exist in the communication network.

[0244] A6. The method of any of embodiments A1 -A5, wherein selectively sending the second EE subscription request to the second data management function comprises: sending the second EE subscription request to the second data management function when the second indication indicates that a subscription for the UE exists in the second core network; and refraining from sending the second EE subscription request to the second data management function when the second indication indicates that no subscription for the UE exists in the second core network.

[0245] A7. The method of any of embodiments A1 -A6, wherein: the first core network is a 5G core network (5GC); the second core network is a 4G evolved packet core network (EPC); the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF); the first data management function is a unified data management (UDM) function; and the second data management function is a home subscriber server (HSS).

[0246] A8. The method of embodiment A7, wherein the second indication is one of the following application error codes: 4G_5G_USER_DOES_NOT_EXIST, 4G USER EXISTS, or 4G_USER_DOES_NOT_EXIST. A9. The method of any of embodiments A7-A8, wherein the first indication that an EE subscription for notifications related to the UE was not successfully created in the first core network is a UE NOT FOUND application error code.

[0247] Bl. A method for a first data management function configured to operate in a first core network of a communication network that also includes a second core network, the method comprising: receiving, from an exposure function of the communication network, a first event exposure (EE) subscription request for notifications from the first core network related to a user equipment (UE), wherein the first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE; determining whether a subscription for the UE exists in the first core network and whether a subscription for the UE exists in the second core network; when it is determined that a subscription for the UE exists in the first core network, attempting to create an EE subscription for notifications from the first core network related to the UE, in accordance with the first EE subscription request; and sending, to the exposure function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and a second indication of whether a subscription for the UE exists in the second core network.

[0248] B2. The method of embodiment Bl, wherein when the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the first core network, the first EE subscription response also includes a further second indication of whether a subscription for the UE exists in the first core network.

[0249] B3. The method of embodiment B2, wherein when the further second indication indicates that a subscription of the UE does not exist in the first core network, one of the following applies: the second indication and the further second indication are a single indication that no subscription for the UE exists in the first core network or the second core network; or the second indication and the further second indication are separate indications.

[0250] B4. The method of any of embodiments B 1-B3, wherein: the first core network is a 5G core network (5GC); the second core network is a 4G evolved packet core network (EPC); the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF); the first data management function is a unified data management (UDM) function; and the second data management function is a home subscriber server (HSS).

[0251] B5. The method of embodiment B4, wherein the second indication is one of the following application error codes: 4G_5G_USER_DOES_NOT_EXIST, 4G USER EXISTS, or 4G_USER_DOES_NOT_EXIST.

[0252] B6. The method of any of embodiments B4-B5, wherein the first indication that an EE subscription for notifications related to the UE was not successfully created in the first core network is a UE NOT FOUND application error code.

[0253] Cl . An exposure function configured to operate in a communication network that includes a first core network and a second core network, the exposure function comprising: communication interface circuitry configured to communicate with a first data management function associated with the first core network; and processing circuitry operatively coupled to the radio transceiver circuitry, whereby the processing circuitry and the radio transceiver circuitry are configured to perform operations corresponding to any of the methods of embodiments A1-A9.

[0254] C2. An exposure function configured to operate in a communication network that includes a first core network and a second core network, the exposure function being further configured to perform operations corresponding to any of the methods of embodiments A1-A9.

[0255] C3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of an exposure function configured to operate in a communication network that includes a first core network and a second core network, configure the exposure function to perform operations corresponding to any of the methods of embodiments A1-A9.

[0256] C4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of an exposure function configured to operate in a communication network that includes a first core network and a second core network, configure the exposure function to perform operations corresponding to any of the methods of embodiments A1-A9.

[0257] DI. A first data management function configured to operate in a first core network of a communication network that also includes a second core network, the first data management function comprising: communication interface circuitry configured to communicate with an exposure function of the communication network and with a second data management function of the second core network; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to any of the methods of embodiments B 1 -B6.

[0258] D2. A first data management function configured to operate in a first core network of a communication network that also includes a second core network, the first data management function being further configured to perform operations corresponding to any of the methods of embodiments B 1-B6.

[0259] D3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a first data management function configured to operate in a first core network of a communication network that also includes a second core network, configure the first data management function to perform operations corresponding to any of the methods of embodiments Bl -B6.

[0260] D4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a first data management function configured to operate in a first core network of a communication network that also includes a second core network, configure the first data management function to perform operations corresponding to any of the methods of embodiments Bl -B6.

[0261] El . A method for an exposure function configured to operate in a communication network that includes a first core network and a second core network, the method comprising: sending, to a first data management function of the first core network, a first event exposure (EE) subscription request for notifications from the first core network related to a user equipment (UE), wherein the first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE; receiving, from the first data management function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, and a second indication that a subscription for the UE does not exist in the first core network; and based on the first indication, selectively sending to the second data management function a second EE subscription request for notifications from the second core network related to the UE.

[0262] E2. The method of embodiment El, wherein the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network.

[0263] E3. The method of embodiment E2, wherein the first EE subscription request includes an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required.

[0264] E4. The method of embodiment E3, wherein the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event.

[0265] E4a. The method of any of embodiments E3-E4, wherein: the first EE subscription request also includes an indication for immediate event reporting; and when the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network, the first EE subscription response also includes a monitoring report for the first event, in accordance with the indication for immediate event reporting.

[0266] E5. The method of any of embodiments E3-E4a, further comprising, when the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network, subsequently receiving from the first data management function an EE notification including the following: a further first indication that an EE subscription for notifications related to the UE was successfully created in the second core network, and a monitoring report from the second core network for the first event.

[0267] E6. The method of any of embodiments E1-E5, further comprising receiving, from an application function (AF) or application server (AS) associated with the communication network, an EE subscription request for notifications from the communication network related to the UE, wherein sending the first EE subscription request is responsive to receiving the EE subscription request from the AF or the AS.

[0268] E7. The method of any of embodiments E1-E6, wherein selectively sending the second EE subscription request to the second data management function comprises: sending the second EE subscription request to the second data management function when the first indication indicates that no EE subscription for notifications related to the UE was successfully created in the second core network; and refraining from sending the second EE subscription request to the second data management function when the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network.

[0269] E8. The method of any of embodiments E1-E7, wherein one or more of the following applies: the second indication is 5G_USER_D0ES_N0T_EXIST application error code; and the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the second core network based on a USER NOT FOUND application error code. E9. The method of any of embodiments E1-E8, wherein: the first core network is a 5G core network (5GC); the second core network is a 4G evolved packet core network (EPC); the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF); the first data management function is a unified data management (UDM) function; and the second data management function is a home subscriber server (HSS).

[0270] Fl. A method for a first data management function configured to operate in a first core network of a communication network that also includes a second core network, the method comprising: receiving, from an exposure function of the communication network, a first event exposure (EE) subscription request for notifications from the first core network related to a user equipment (UE), wherein the first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE; determining that a subscription for the UE does not exist in the first core network; determining the following: whether user subscription data for the second core network is accessible to the first data management function, and if determined to be accessible, whether the user subscription data for the second core network includes a subscription for the UE; attempting to create an EE subscription for notifications from the second core network related to the UE, in accordance with the first EE subscription request, in response to each of the following conditions: the user subscription data for the second core network includes a subscription for the UE; and the first data management function is unable to determine whether the user subscription data for the second core network includes a subscription for the UE; and sending, to the exposure function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, and a second indication that a subscription for the UE does not exist in the first core network.

[0271] F2. The method of embodiment Fl, wherein attempting to create an EE subscription for notifications from the second core network related to the UE comprises: sending, to a second data management function of the second core network, a second EE subscription request for notifications from the second core network related to the UE; and receiving from the second data management function a second EE subscription response including the first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, wherein the first EE subscription response is based on the second EE subscription response.

[0272] F3. The method of embodiment F2, wherein the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network.

[0273] F4. The method of embodiment F3, wherein the first and second EE subscription requests include an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required.

[0274] F5. The method of embodiment F4, wherein the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event.

[0275] F5a. The method of any of embodiments F4-F5, wherein: the first EE subscription request also includes an indication for immediate event reporting; and when the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network, the first EE subscription response also includes a monitoring report for the first event, in accordance with the indication for immediate event reporting.

[0276] F6. The method of any of embodiments F4-F5a, further comprising: when the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network, subsequently receiving from the second data management function a first EE notification including the following: a further first indication that an EE subscription for notifications related to the UE was successfully created in the second core network, and a monitoring report for the first event; and sending to the exposure function a second EE notification including the further first indication and the monitoring report.

[0277] F7. The method of any of embodiments F1-F6, wherein one or more of the following applies: the second indication is 5G_USER_DOES_NOT_EXIST application error code; and the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the second core network based on a USER NOT FOUND application error code.

[0278] F8. The method of any of embodiments F1-F7, wherein determining whether user subscription data for the second core network is accessible to the first data management function comprises determining, based on a configuration flag, whether a user subscription repository for the second core network is consolidated with a user subscription repository for the first core network, which is accessible to the first data management function.

[0279] F9. The method of any of embodiments F1-F8, wherein: the first core network is a 5G core network (5GC); the second core network is a 4G evolved packet core network (EPC); the exposure function is a network exposure function (NEF) or a service capabilities exposure function (SCEF); and the first data management function is a unified data management (UDM) function.

[0280] Gl. A method for a second data management function configured to operate in a second core network of a communication network that also includes a first core network, the method comprising: receiving, from a first data management function of the first core network, a second event exposure (EE) subscription request for notifications from the second core network related to a user equipment (UE), wherein a subscription for the UE does not exist in the first core network; attempting to create an EE subscription for notifications from the second core network related to the UE, in accordance with the second EE subscription request; and sending to the first data management function a second EE subscription response including a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network.

[0281] G2. The method of embodiment Gl, wherein the first indication indicates that an EE subscription for notifications related to the UE was successfully created in the second core network.

[0282] G3. The method of embodiment G2, wherein the second EE subscription request includes an indication of a first event for which synchronization of monitoring status between the first and second data management functions is required.

[0283] G4. The method of embodiment G3, wherein the first event is one of the following: a UE roaming status change event, or a UE IMEI(SV) / PEI change event.

[0284] G4a. The method of any of embodiments G3-G4, wherein: the second EE subscription request also includes an indication for immediate event reporting; the method further comprises detecting the first event after an EE subscription for notifications related to the UE was successfully created in the second core network; and the second EE subscription response also includes a monitoring report for the detected first event, in accordance with the indication for immediate event reporting.

[0285] G5. The method of any of embodiments G3-G4a, further comprising: detecting the first event after sending the second EE subscription response including a first indication that an EE subscription for notifications related to the UE was successfully created in the second core network; and sending to the first data management function a first EE notification including the following: a further first indication that an EE subscription for notifications related to the UE was successfully created in the second core network, and a monitoring report for the detected first event.

[0286] G6. The method of any of embodiments G1-G5, further comprising determining whether a subscription for the UE exists in the second core network, wherein attempting to create the EE subscription for notifications from the second core network is based on determining that a subscription for the UE exists in the second core network

[0287] G7. The method of embodiment G6, wherein when it is determined that a subscription for the UE does not exist in the second core network, the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the second core network based on a USER NOT FOUND application error code.

[0288] G8. The method of any of embodiments G1-G7, wherein one of the following applies: the first data management function is unable to determine whether user subscription data for the second core network includes a subscription for the UE; or user subscription data for the second core network is accessible to the first data management function and includes a subscription for the UE.

[0289] G9. The method of any of embodiments G1-G8, wherein: the first core network is a 5G core network (5GC); the second core network is a 4G evolved packet core network (EPC); the first data management function is a unified data management (UDM) function; and the second data management function is a home subscriber server (HSS).

[0290] Hl. An exposure function configured to operate in a communication network that includes a first core network and a second core network, the exposure function comprising: communication interface circuitry configured to communicate with a first data management function associated with the first core network; and processing circuitry operatively coupled to the radio transceiver circuitry, whereby the processing circuitry and the radio transceiver circuitry are configured to perform operations corresponding to any of the methods of embodiments E1-E9. H2. An exposure function configured to operate in a communication network that includes a first core network and a second core network, the exposure function being further configured to perform operations corresponding to any of the methods of embodiments E1-E9.

[0291] H3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of an exposure function configured to operate in a communication network that includes a first core network and a second core network, configure the exposure function to perform operations corresponding to any of the methods of embodiments E1-E9.

[0292] H4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of an exposure function configured to operate in a communication network that includes a first core network and a second core network, configure the exposure function to perform operations corresponding to any of the methods of embodiments E1-E9.

[0293] 11. A first data management function configured to operate in a first core network of a communication network that also includes a second core network, the first data management function comprising: communication interface circuitry configured to communicate with an exposure function of the communication network and with a second data management function of the second core network; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to any of the methods of embodiments F1-F9.

[0294] 12. A first data management function configured to operate in a first core network of a communication network that also includes a second core network, the first data management function being further configured to perform operations corresponding to any of the methods of embodiments F1-F9.

[0295] 13. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a first data management function configured to operate in a first core network of a communication network that also includes a second core network, configure the first data management function to perform operations corresponding to any of the methods of embodiments F1-F9.

[0296] 14. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a first data management function configured to operate in a first core network of a communication network that also includes a second core network, configure the first data management function to perform operations corresponding to any of the methods of embodiments F1-F9.

[0297] JI. A second data management function configured to operate in a second core network of a communication network that also includes a first core network, the second data management function comprising: communication interface circuitry configured to communicate with an exposure function of the communication network and with a first data management function of the first core network; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to any of the methods of embodiments G1-G9.

[0298] J2. A second data management function configured to operate in a second core network of a communication network that also includes a first core network, the second data management function being further configured to perform operations corresponding to any of the methods of embodiments G1-G9.

[0299] J3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a second data management function configured to operate in a second core network of a communication network that also includes a first core network, configure the second data management function to perform operations corresponding to any of the methods of embodiments G1-G9.

[0300] J4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a second data management function configured to operate in a second core network of a communication network that also includes a first core network, configure the second data management function to perform operations corresponding to any of the methods of embodiments G1-G9.

Claims

CLAIMS1. A method for an exposure function configured to operate in a communication network that includes a first core network and a second core network, the method comprising: sending (1520), to a first data management function of the first core network, a first event exposure, EE, subscription request for notifications from the first core network related to a user equipment, UE, wherein the first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE; receiving (1530), from the first data management function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and a second indication of whether a subscription for the UE exists in the second core network; and based on the second indication, selectively sending (1540) to the second data management function a second EE subscription request for notifications from the second core network related to the UE.

2. The method of claim 1, wherein when the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the first core network, the first EE subscription response also includes a further second indication of whether a subscription for the UE exists in the first core network.

3. The method of claim 2, wherein when the further second indication indicates that a subscription of the UE does not exist in the first core network, one of the following applies: the second indication and the further second indication are a single indication that no subscription for the UE exists in the first core network or the second core network; or the second indication and the further second indication are separate indications.

4. The method of any of claims 2 to 3, further comprising receiving, from an application function, AF, or application server, AS, associated with the communication network, an EE subscription request for notifications from the communication network related tothe UE, wherein sending the first EE subscription request is responsive to receiving the EE subscription request from the AF or the AS.

5. The method of claim 4, further comprising, when the second indication indicates that a subscription of the UE does not exist in the second core network and the further second indication indicates that a subscription of the UE does not exist in the first core network, sending to the AF or the AS an EE subscription response indicating that a subscription for the UE does not exist in the communication network.

6. The method of any of claims 1 to 5, wherein selectively sending the second EE subscription request to the second data management function comprises: sending the second EE subscription request to the second data management function when the second indication indicates that a subscription for the UE exists in the second core network; and refraining from sending the second EE subscription request to the second data management function when the second indication indicates that no subscription for the UE exists in the second core network.

7. The method of any of claims 1 to 6, wherein: the first core network is a 5G core network, 5GC; the second core network is a 4G evolved packet core network, EPC; the exposure function is a network exposure function, NEF, or a service capabilities exposure function, SCEF; the first data management function is a unified data management, UDM, function; and the second data management function is a home subscriber server, HSS.

8. The method of claim 7, wherein the second indication is one of the following application error codes: 4G_5G_USER_DOES_NOT_EXIST, 4G USER EXISTS, or 4G_USER_D0ES_N0T_EXIST.

9. The method of any of claims 7 to 8, wherein the first indication that an EE subscription for notifications related to the UE was not successfully created in the first core network is a UE NOT FOUND application error code.

10. A method for a first data management function configured to operate in a first core network of a communication network that also includes a second core network, the method comprising: receiving (1610), from an exposure function of the communication network, a first event exposure, EE, subscription request for notifications from the first core network related to a user equipment, UE, wherein the first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE; determining (1620) whether a subscription for the UE exists in the first core network and whether a subscription for the UE exists in the second core network; when it is determined that a subscription for the UE exists in the first core network, attempting (1630) to create an EE subscription for notifications from the first core network related to the UE, in accordance with the first EE subscription request; and sending (1640), to the exposure function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the first core network, and a second indication of whether a subscription for the UE exists in the second core network.

11. The method of claim 10, wherein when the first indication indicates that an EE subscription for notifications related to the UE was not successfully created in the first core network, the first EE subscription response also includes a further second indication of whether a subscription for the UE exists in the first core network.

12. The method of claim 11, wherein when the further second indication indicates that a subscription of the UE does not exist in the first core network, one of the following applies: the second indication and the further second indication are a single indication that no subscription for the UE exists in the first core network or the second core network; or the second indication and the further second indication are separate indications.

13. The method of any of claims 10 to 12, wherein: the first core network is a 5G core network, 5GC; the second core network is a 4G evolved packet core network, EPC;the exposure function is a network exposure function, NEF, or a service capabilities exposure function, SCEF; the first data management function is a unified data management, UDM, function; and the second data management function is a home subscriber server, HSS.

14. The method of claim 13, wherein the second indication is one of the following application error codes: 4G_5G_USER_DOES_NOT_EXIST, 4G USER EXISTS, or 4G_USER_DOES_NOT_EXIST.

15. The method of any of claims 13 to 14, wherein the first indication that an EE subscription for notifications related to the UE was not successfully created in the first core network is a UE NOT FOUND application error code.

16. An exposure function configured to operate in a communication network that includes a first core network and a second core network, the exposure function comprising: communication interface circuitry configured to communicate with a first data management function associated with the first core network; and processing circuitry operatively coupled to the radio transceiver circuitry, whereby the processing circuitry and the radio transceiver circuitry are configured to perform operations corresponding to any of the methods of claims 1 to 9.

17. An exposure function configured to operate in a communication network that includes a first core network and a second core network, the exposure function being further configured to perform operations corresponding to any of the methods of claims 1 to 9.

18. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of an exposure function configured to operate in a communication network that includes a first core network and a second core network, configure the exposure function to perform operations corresponding to any of the methods of claims 1 to 9.

19. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of an exposure function configured to operate in a communication network that includes a first core network and a second core network,configure the exposure function to perform operations corresponding to any of the methods of claims 1 to 9.

20. A first data management function configured to operate in a first core network of a communication network that also includes a second core network, the first data management function comprising: communication interface circuitry configured to communicate with an exposure function of the communication network and with a second data management function of the second core network; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to any of the methods of claims 10 to 15.

21. A first data management function configured to operate in a first core network of a communication network that also includes a second core network, the first data management function being further configured to perform operations corresponding to any of the methods of claims 10 to 15.

22. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a first data management function configured to operate in a first core network of a communication network that also includes a second core network, configure the first data management function to perform operations corresponding to any of the methods of claims 10 to 15.

23. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a first data management function configured to operate in a first core network of a communication network that also includes a second core network, configure the first data management function to perform operations corresponding to any of the methods of claims 10 to 15.

24. A method for an exposure function configured to operate in a communication network that includes a first core network and a second core network, the method comprising: sending (920), to a first data management function of the first core network, a first event exposure, EE, subscription request for notifications from the first core network related to a user equipment, UE, wherein the first EE subscription request includes anindication for a corresponding EE subscription for notifications from the second core network related to the UE; receiving (930), from the first data management function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, and a second indication that a subscription for the UE does not exist in the first core network; and based on the first indication, selectively sending (940) to the second data management function a second EE subscription request for notifications from the second core network related to the UE.

25. A method for a first data management function configured to operate in a first core network of a communication network that also includes a second core network, the method comprising: receiving (1010), from an exposure function of the communication network, a first event exposure, EE, subscription request for notifications from the first core network related to a user equipment, UE, wherein the first EE subscription request includes an indication for a corresponding EE subscription for notifications from the second core network related to the UE; determining (1020) that a subscription for the UE does not exist in the first core network; determining (1030) the following: whether user subscription data for the second core network is accessible to the first data management function, and if determined to be accessible, whether the user subscription data for the second core network includes a subscription for the UE; attempting (1040) to create an EE subscription for notifications from the second core network related to the UE, in accordance with the first EE subscription request, in response to each of the following conditions: the user subscription data for the second core network includes a subscription for the UE; and the first data management function is unable to determine whether the user subscription data for the second core network includes a subscription for the UE; andsending (1050), to the exposure function, a first EE subscription response including the following: a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network, and a second indication that a subscription for the UE does not exist in the first core network.

26. A method for a second data management function configured to operate in a second core network of a communication network that also includes a first core network, the method comprising: receiving (1110), from a first data management function of the first core network, a second event exposure, EE, subscription request for notifications from the second core network related to a user equipment, UE, wherein a subscription for the UE does not exist in the first core network; attempting (1130) to create an EE subscription for notifications from the second core network related to the UE, in accordance with the second EE subscription request; and sending (1150) to the first data management function a second EE subscription response including a first indication of whether an EE subscription for notifications related to the UE was successfully created in the second core network.

27. An exposure function configured to operate in a communication network that includes a first core network and a second core network, the exposure function comprising: communication interface circuitry configured to communicate with a first data management function associated with the first core network; and processing circuitry operatively coupled to the radio transceiver circuitry, whereby the processing circuitry and the radio transceiver circuitry are configured to perform operations corresponding to the method of claim 24.

28. An exposure function configured to operate in a communication network that includes a first core network and a second core network, the exposure function being further configured to perform operations corresponding to the method of claim 24.

29. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of an exposure function configured to operate in a communication network that includes a first core network and a second corenetwork, configure the exposure function to perform operations corresponding to the method of claim 24.

30. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of an exposure function configured to operate in a communication network that includes a first core network and a second core network, configure the exposure function to perform operations corresponding to the method of claim 24.

31. A first data management function configured to operate in a first core network of a communication network that also includes a second core network, the first data management function comprising: communication interface circuitry configured to communicate with an exposure function of the communication network and with a second data management function of the second core network; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the method of claim 25.

32. A first data management function configured to operate in a first core network of a communication network that also includes a second core network, the first data management function being further configured to perform operations corresponding to the method of claim 25.

33. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a first data management function configured to operate in a first core network of a communication network that also includes a second core network, configure the first data management function to perform operations corresponding to the method of claim 25.

34. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a first data management function configured to operate in a first core network of a communication network that also includes a second core network, configure the first data management function to perform operations corresponding to the method of claim 25.

35. A second data management function configured to operate in a second core network of a communication network that also includes a first core network, the second data management function comprising: communication interface circuitry configured to communicate with an exposure function of the communication network and with a first data management function of the first core network; and processing circuitry operatively coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the method of claim 26.

36. A second data management function configured to operate in a second core network of a communication network that also includes a first core network, the second data management function being further configured to perform operations corresponding to the method of claim 26.

37. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a second data management function configured to operate in a second core network of a communication network that also includes a first core network, configure the second data management function to perform operations corresponding to the method of claim 26.

38. A computer program product comprising computer-executable instructions that, when executed by processing circuitry of a second data management function configured to operate in a second core network of a communication network that also includes a first core network, configure the second data management function to perform operations corresponding to the method of claim 26.

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