Authorization of notification providers

Abstract

Embodiments include methods performed by a receiver network function (NF) arranged to receive notifications from notifier NFs of a communication network. Such methods include sending, to a first NF of the communication network, a first message related to a subscription for receiving notifications from a notifier NF of the communication network. Such methods include receiving, from the notifier NF, a notification in accordance with the subscription. The notification includes or is received in association with a first access token indicating that the notifier NF is authorized to send the notification. Other embodiments include complementary methods performed by notifier NFs, authorization servers, and subscriber NFs, as well as network nodes / functions that perform such methods.

Description

[0001] AUTHORIZATION OF NOTIFICATION PROVIDERS

[0002] TECHNICAL FIELD

[0003] The present application relates generally to the field of communication networks, and more specifically to techniques for ensuring that notifications of available data are only sent by network functions (NFs) in a communication network that are authorized to provide such notifications.

[0004] INTRODUCTION

[0005] Currently the fifth generation (5G) of cellular systems is being standardized within the Third-Generation Partnership Project (3GPP). 5G is developed for maximum flexibility to support many different use cases including enhanced mobile broadband (eMBB), machine type communications (MTC), ultra-reliable low latency communications (URLLC), side-link device- to-device (D2D), and several other use cases.

[0006] At a high level, the 5G System (5GS) consists of an Access Network (AN) and a Core Network (CN). The AN provides user equipment (UEs) with connectivity to the CN, e.g., via base stations such as gNBs or ng-eNBs described below. The CN includes a variety of Network Functions (NFs) that provide a wide range of different functionalities such as session management, connection management, charging, authentication, etc. User equipment (UEs) communicates with the CN over the Non-Access Stratum (NAS), and with the AN over the Access Stratum (AS). Security for the communications over this these strata is provided by the NAS protocol and packet data convergence protocol (PDCP) for AS.

[0007] Figure 1 illustrates a high-level view of an exemplary 5G network architecture, consisting of a Next Generation Radio Access Network (NG-RAN, 199) and a 5G Core (5GC, 198). The NG-RAN can include one or more gNodeB’s (gNBs) connected to the 5GC via one or more NG interfaces, such as gNBs (100, 150) connected via respective interfaces (102, 152). More specifically, the gNBs can be connected to one or more Access and Mobility Management Functions (AMFs) in the 5GC via respective NG-C interfaces and to one or more User Plane Functions (UPFs) in 5GC via respective NG-U interfaces.

[0008] In addition, the gNBs can be connected to each other via one or more Xn interfaces, such as Xn interface (140) between gNBs (100, 150). The radio technology for the NG-RAN is often referred to as “New Radio” (NR). With respect to the NR interface to UEs, each of the gNBs can support frequency division duplexing (FDD), time division duplexing (TDD), or a combination thereof. Each of the gNBs can serve a geographic coverage area including one or more cells and, in some cases, can also use various directional beams to provide coverage in the respective cells. In general, a DL “beam” is a coverage area of a network-transmitted reference signal (RS) that may be measured or monitored by a UE. The NG-RAN is layered into a Radio Network Layer (RNL) and a Transport Network Layer (TNL). The NG-RAN logical nodes and interfaces between them, is defined as part of the RNL. For each NG-RAN interface (NG, Xn, Fl) the related TNL protocol and the functionality are specified. The TNL provides services for user plane transport and signaling transport.

[0009] NG RAN logical nodes (e.g., gNB 100) include a Central Unit (CU or gNB-CU, e.g., 110) and one or more Distributed Units (DU or gNB-DU, e.g., 120, 130). CUs are logical nodes that host higher-layer protocols and perform various gNB functions such controlling the operation of DUs. DUs are decentralized logical nodes that host lower layer protocols and can include, depending on the functional split option, various subsets of the gNB functions. Each CU and DU can include various circuitry needed to perform their respective functions, including processing circuitry, communication interface circuitry e.g., transceivers), and power supply circuitry.

[0010] A gNB-CU connects to one or more gNB-DUs over respective Fl logical interfaces (e.g., 122 and 132 shown in Figure 1). However, each gNB-DU can be connected to only one gNB-CU. The gNB-CU and its connected gNB-DU(s) are only visible to other gNBs and the 5GC as a gNB. In other words, the Fl interface is not visible beyond gNB-CU.

[0011] Another change in 5G networks (e.g., in 5GC) is that traditional peer-to-peer interfaces and protocols found in earlier-generation networks 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.

[0012] 3GPP TS 33.501 (vl7.8.0) describes security architecture and procedures for the 5G system, including the SBA. One security technique used in the SBA is token-based authorization. For example, 3GPP TS 33.501 section 13.4.1 discusses authorization of access to NF services using the OAuth 2.0 framework described in IETF RFC 6749 based on access tokens secured by digital signatures.

[0013] 3GPP TR 33.875 (vl.6.0) describes a "Study on enhanced security aspects of the 5G Service Based Architecture (SBA)". One issue (called “Key Issue #3”) addressed by this study is service access in "Subscribe / Notify" scenarios, particularly the risk that a service producer NF (NFp) may send a notification message to an unauthorized service consumer NF (NFc). There are some proposals to authorize a notification uniform resource identifier (URI) by the NRF and provide an access token with the authorized notification URI to the NFc, which can use it when subscribing for notifications. SUMMARY

[0014] Even if an NFc is authorized to receive notifications for a subscription, it is unclear how the NFc can be sure that a notification is from a notifier NF (e.g., NFp) that is authorized to send notifications to the NFc. For example, a notification URI can obtained by an unauthorized third party, who could use it to send false notifications to provoke NFc actions with undesirable consequences.

[0015] An object of embodiments of the present disclosure is to address these and other problems, issues, and / or difficulties, thereby enabling the otherwise-advantageous deployment of SBA in a 5G system.

[0016] Some embodiments of the present disclosure include methods e.g., procedures) for a receiver network function (NF) arranged to receive notifications from notifier NFs of a communication network (e.g., 5GC).

[0017] These exemplary methods can include sending, to a first NF of the communication network, a first message related to a subscription for receiving notifications from a notifier NF of the communication network. These exemplary methods can also include receiving, from the notifier NF, a notification in accordance with the subscription. The notification includes or is received in association with a first access token indicating that the notifier NF is authorized to send the notification.

[0018] In some embodiments, the first NF is the notifier NF and the first message is a subscription request for notifications from the notifier NF. In other embodiments, the first NF is a subscriber NF different from the receiver NF and the first message is a service request indicating that the subscriber NF should subscribe to notifications on behalf of the receiver NF.

[0019] In some embodiments, the first message includes one or more of the following information:

[0020] • an indication of whether the subscription is implicit or explicit;

[0021] • an identifier of the subscription;

[0022] • a first validity duration associated with the subscription;

[0023] • a notification type associated with the subscription;

[0024] • a callback uniform resource identifier (URI) at which the receiver NF can receive the notifications;

[0025] • a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated;

[0026] • one or more of the following associated with the receiver NF: NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and • one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

[0027] In some of these embodiments, the first access token includes one or more of the following information that is also included in the first message: the identifier of the subscription, the callback URI, the callback URI schema, and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances. In some variants of these embodiments, these exemplary methods can also include verifying that the receiving NF is the intended recipient of the notification based on the information included in both the first access token and the first message.

[0028] In some embodiments, these exemplary methods can also include registering a NF profile of the receiver NF with an authorization server of the communication network. The registered NF profile includes one or more of the following: a callback URI schema, from which callback URIs for the receiver NF can be generated; and allowed NF information that identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF.

[0029] In some embodiments, the first message includes a second access token indicating that the receiver NF is authorized to subscribe to the notifications from the notifier NF. In some embodiments, the receiver NF is an access and mobility management function (AMF) and / or the notifier NF is a unified data management (UDM) function.

[0030] Other embodiments include exemplary methods (e.g., procedures) for a notifier NF arranged to send notifications to receiver NFs in a communication network (e.g., 5GC).

[0031] These exemplary methods can include receiving, from a first NF of the communication network, a first message related to a subscription for a receiver NF to receive notifications from the notifier NF. These exemplary methods can also include sending, to an authorization server of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to the receiver NF. These exemplary methods can also include receiving from the authorization server a first access token in accordance with the access token request. These exemplary methods can also include sending to the receiver NF a notification in accordance with the subscription request. The notification includes or is sent in association with the first access token.

[0032] In some embodiments, the first message is a subscription request for notifications from the notifier NF and the first NF is the receiver NF or a subscriber NF authorized to subscribe to notifications on behalf of the receiver NF. In other embodiments, the first NF is a subscriber NF different from the receiver NF and the first message is a service request indicating that the subscriber NF should subscribe to notifications on behalf of the receiver NF. In other embodiments, the first NF is the authorization server and these exemplary methods can also include sending to the authorization server a discovery request to identify NFs of the communication network that are subscribed to notifications provided by the notifier NF. In such case, the first message is a discovery response received in response to the discovery request.

[0033] In various embodiments, the first message can include any of the information summarized above in relation to receiver NF embodiments. In various embodiments, the first access token can include any of the information summarized above in relation to receiver NF embodiments.

[0034] In some embodiments, the access token request includes an indication that the requested access token is for notifications and one or more of the following information that was included in the first message:

[0035] • the identifier of the subscription;

[0036] • the first validity duration associated with the subscription;

[0037] • the callback URI;

[0038] • the callback URI schema;

[0039] • the notification type associated with the subscription; and

[0040] • one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0041] In some embodiments, the authorization server is an NRF, the receiver NF is an AMF, and / or the notifier NF is a UDM function.

[0042] Other embodiments include methods (e.g., procedures) for an authorization server of a communication network.

[0043] These exemplary methods can include receiving, from a notifier NF of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to a receiver NF of the communication network. These exemplary method can also include authorizing the access token request based on an NF profile for the receiver NF that is registered in the authorization server. These exemplary methods can also include, based on authorizing the access token request, sending to the notifier NF a first access token in accordance with the access token request.

[0044] In various embodiments, the first message can include any of the information summarized above in relation to receiver NF embodiments. In various embodiments, the first access token can include any of the information summarized above in relation to receiver NF embodiments. In various embodiments, the access token request can include any of the information summarized above in relation to notifier NF embodiments.

[0045] In some embodiments, these exemplary methods can also include registering a NF profile of the receiver NF. The registered NF profile includes one or more of the following: a callback URI schema, from which callback URIs for the receiver NF can be generated; and allowed NF information that identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF. In some of these embodiments, authorizing the access token request is based on detecting one or more of the following:

[0046] • a match or correspondence between the allowed NF information in the registered NF profile and one or more of the following associated with the notifier NF: NF type, NF set, and one or more NF instances; and

[0047] • a match or correspondence between the callback URI schema in the registered NF profile and a callback URI schema in the access token request.

[0048] In some embodiments, the authorization server is an NRF, the receiver NF is an AMF, and / or the notifier NF is a UDM function.

[0049] Other embodiments include methods (e.g., procedures) for a subscriber NF arranged to subscribe to notifications from a notifier NF of a communication network on behalf of a receiver NF of the communication network (e.g., 5GC).

[0050] These exemplary methods can include receiving, from the receiver NF, a service request indicating that the subscriber NF should subscribe to notifications from the notifier NF on behalf of the receiver NF. These exemplary methods can also include sending to the notifier NF a subscription request in accordance with the service request.

[0051] In some embodiments, the service request can include any of the information included in the first message summarized above in relation to receiver NF embodiments. In some embodiments, the subscription request includes the information included in the service request and an indication of whether the subscription is implicit or explicit.

[0052] In some embodiments, the subscriber NF is a first AMF, the notifier NF is a UDM function, and the receiver NF is a second AMF different than the first AMF.

[0053] Other embodiments include receiver NFs, notifier NFs, authorization servers, and subscriber NFs (or network nodes hosting the same) that are configured to perform the operations corresponding to any of the exemplary methods described herein. Other embodiments also include non-transitory, computer-readable media storing computerexecutable instructions that, when executed by processing circuitry associated with such receiver NFs, notifier NFs, authorization servers, and subscriber NFs, configure the same to perform operations corresponding to any of the exemplary methods described herein.

[0054] These and other embodiments described herein can improve security in a communication network by an access token that indicates a producer NF that is authorized (e.g., by NRF) to provide notifications related to subscriptions. This information in the access token can be used by the consumer NF to ensure that it receives notifications only from authorized senders. This can improve security of the 5G SBA by mitigating various attack scenarios.

[0055] These and other objects, features, and advantages of the present disclosure will become apparent upon reading the following Detailed Description in view of the Drawings briefly described below.

[0056] BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figures 1-2 illustrate various aspects of an exemplary 5G network architecture.

[0058] Figures 3-5 illustrates various arrangements in which a service consumer NF subscribes to notifications from a service producer NF.

[0059] Figures 6A-B show various aspects of a procedure for a service consumer NF to obtain an access token for accessing services provided by a service producer NF.

[0060] Figure 7 is a signaling diagram of a procedure for a service consumer NF to obtain an access token for subscribing to notifications from a service producer NF.

[0061] Figures 8-11 show signaling diagrams of various procedures for obtaining and using an access token for sending notifications, according to various embodiments of the present disclosure.

[0062] Figure 12 shows an arrangement of NF sets of service consumer NFs and service producer NFs, according to some embodiments of the present disclosure.

[0063] Figure 13 shows an exemplary method (e.g., procedure) for a receiver NF of a communication network, according to various embodiments of the present disclosure.

[0064] Figure 14 shows an exemplary method (e.g., procedure) for a notifier NF of a communication network, according to various embodiments of the present disclosure.

[0065] Figure 15 shows an exemplary method (e.g., procedure) for an authorization server of a communication network, according to various embodiments of the present disclosure.

[0066] Figure 16 shows an exemplary method (e.g., procedure) for a subscriber NF of a communication network, according to various embodiments of the present disclosure.

[0067] Figure 17 shows a communication system according to various embodiments of the present disclosure.

[0068] Figure 18 shows a network node according to various embodiments of the present disclosure.

[0069] 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

[0070] 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.

[0071] 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 to be 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.

[0072] Furthermore, the following terms are used throughout the description given below:

[0073] • Radio Access Node: 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 3 GPP 5G / NR network or an enhanced or eNB in a 3GPP LTE network), base station distributed components (e.g., CU and DU), a high-power or macro base station, a low-power base station (e.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.

[0074] • Core Network Node: 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 (SGW), a PDN 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 terms having a different meaning than the term “network node”.

[0075] • Radio Node: As used herein, a “radio node” can be either a “radio access node” (or equivalent term) or a “wireless device.”

[0076] • Network Node: 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 (c.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.

[0077] • Node: As used herein, the term “node” (without prefix) can be any type of node that can 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.

[0078] 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.

[0079] Note that the description given herein focuses on a 3 GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system and can be applied to any communication system that may benefit from them.

[0080] Figure 2 shows an exemplary non-roaming reference architecture for a 5G network (200). These include the following 3GPP-defined NFs and service-based interfaces:

[0081] • 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.

[0082] • 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.

[0083] 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 data network (PDN) via the N6 reference point. The N9 reference point is for communication between two UPFs.

[0084] • Session Management Function (SMF, with Nsmf 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.

[0085] • Charging Function (CHF, with Nchf interface) - 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.

[0086] Access and Mobility Management Function (AMF, 210, 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.

[0087] • 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.

[0088] • Network Repository Function (NRF, 230, with Nnrf interface) - provides service registration and discovery, enabling NFs to identify appropriate services available from other NFs.

[0089] • 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.

[0090] • 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.

[0091] • Network Data Analytics Function (NWDAF, 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.

[0092] • Location Management Function (LMF, with Nlmf interface) - supports various functions related to determination of LIE locations, including location determination for a LE and obtaining any of the following: DL location measurements or a location estimate from the LE; LE location measurements from the NG RAN; and non-LE associated assistance data from the NG RAN.

[0093] Unified Data Management (UDM) function (220) supports generation of 3 GPP authentication credentials, user identification handling, access authorization based on subscription data, and other subscriber-related functions. To provide this functionality, the UDM uses subscription data (including authentication data) stored in the 5GC unified data repository (UDR). In addition to the UDM, the UDR supports storage and retrieval of policy data by the PCF, as well as storage and retrieval of application data by NEF. Data Storage Functions (DSF) allow NFs to store context.

[0094] The 5G SBA model is based on principles including modularity, reusability, and selfcontainment of NFs, which can enable network deployments to take advantage of the latest virtualization and software technologies. 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, “service consumer NF”) requests a service producer NF (or equivalently, “service 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.

[0095] Figure 3 shows an exemplary "Subscribe / Notify" arrangement in which a service consumer NF (e.g., NF_A 310) subscribes to notifications from a service producer NF (e.g., NF_B 320), either explicitly or implicitly. The subscription or service request includes the notification endpoint (e.g., notification URL) of the service consumer NF. In this scenario, NF_A subscribes to the service of NF_B for itself.

[0096] Figure 4 shows another exemplary "Subscribe / Notify" arrangement in which one service consumer NF (e.g., NF_A 310) subscribes to notifications from a service producer NF (e.g., NF_B 320), either explicitly or implicitly, on behalf of another service consumer NF (e.g., NF_C 330). The notification URI of NR_C is included in the subscription request, and NF C will receive the notification message even though the subscribe request is sent by NF_A.

[0097] Figure 5 shows another exemplary "Subscribe / Notify" arrangement whereby a service consumer NF (e.g., NF_A 310) uses an SCP (340) for indirect communication with the service producer NF (e.g., NF_B 320). The SCP routes messages between service consumer NFs and service producer NFs based on the Routing Binding Indication (if available) and may perform discovery and associated selection of the service producer NF on behalf of a service consumer NF. In Figure 5, the SCP forwards the subscription request to NF_B but since the subscription is on behalf of NF C (330), the SCP forwards notifications from NF_B to NF C.

[0098] 3GPP TS 33.501 (vl7.8.0) describes security architecture and procedures for the 5G system, including the SBA. One security technique used in the SBA is token-based authorization. For example, 3GPP TS 33.501 section 13.4.1 discusses authorization of access to NF services using the OAuth 2.0 framework described in IETF RFC 6749 based on access tokens secured by digital signatures. In particular, a service consumer NF (NFc) acts as an OAuth 2.0 client, the service producer NF (NFp) acts as an OAuth 2.0 resource server, and the NRF acts as an OAuth 2.0 authorization server.

[0099] Figure 6A is a flow diagram of an exemplary procedure for a service producer NF (NFp, 610) to register as an OAuth 2.0 resource server with NRF (620). In operation 1, the NFp invokes an Nnrf NFManagement NFRegister Request service operation to provide its NF profile for registration in NRF. The NF profile configuration data of the NFp may include "additional scope" information that indicates NFp resources and service operations that are allowed for an NFc. These resources may be per NF type or per NF instance ID of the NFc. In operations 2-3, the NRF stores the NF profile provided by the NFp and responds with an Nnrf NFManagement NFRegister Response service operation indicating successful registration.

[0100] Figure 6B is a flow diagram of an exemplary procedure for a service consumer NF (NFc, 630) to obtain an access token for accessing services provided by a service producer NF (NFp, e.g., 610 in Figure 6A). For example, the procedure shown in Figure 6B may be based on successful completion of the procedure shown in Figure 6A.

[0101] In operation 1, the NFc requests an access token from the NRF in the same public land mobile network (PLMN) using the Nnrf AccessToken Get request operation. The request message includes the NF Instance ID(s) of the service consumer NF, the requested "scope" including the expected NF Service name(s). The message may include "additional scope" information such as requested resources, requested actions (e.g., service operations) on the resources, and NF type(s) of the expected NFp instance and the NFc.

[0102] The NFc may also include a list of NSSAIs or list of NSI IDs for the expected NFp instances. NSSAI is a group of one or more single network slice selection assistance information (S-NSSAI), each of which includes a slice type (SST) field that describes expected network behavior and optionally a slice differentiator (SD) field that provides further behavior differentiation. In some cases, the NFc may also include a list of S-NSSAIs of the service consumer NF. In some cases, the NFc may also include the NF Set ID of the expected NFp instances.

[0103] The requested service or service operation can be a “subscription request”, e.g., an explicit subscription or any other kind of service invocation that can be interpreted as an implicit subscription. In the embodiments illustrated by Figure 6B, the message includes a consumer NF Set list for the expected alternative notification receivers.

[0104] In operation 2, the NRF verifies that the input parameters (e.g., NF type, consumer NF Set list) in the access token request match with the corresponding ones in the public key certificate of the NFc or with those in the NF profile of the NFc. The NRF checks whether the NFc is authorized to access the requested service(s). If the NFc is authorized, the NRF generates an access token with appropriate AccessTokenClaims included. The NRF digitally signs the generated access token based on a shared secret or private key as described in RFC 7515 published by the IETF. If the NFc is not authorized, the NRF does not issue an access token to the NFc.

[0105] The AccessTokenClaims in the token include the NF Instance ID of NRF (issuer), NF Instance ID of the NFc (subject), NF type of the NFp (audience), expected service name(s), (scope), expiration time (expiration) and optionally "additional scope" information such as allowed resources and allowed actions (service operations) on the resources. The AccessTokenClaims may include a list of NSSAIs or NSI IDs for the expected service producer NF instances, and / or the NF Set ID of the expected service producer NF instances.

[0106] If the authorization is successful in operation 2, in operation 3 the NRF sends the access token with the above information to the service consumer NF using Nnrf AccessToken GetResponse . The other parameters (e.g., expiration time, allowed scope) sent by NRF in addition to the access token are described in 3GPP TS 29.510. If the authorization is unsuccessful in operation 2, the NRF replies in operation 3 based on OAuth 2.0 error response defined in IETF RFC 6749.

[0107] The NFc can then send the received access token to the NFp in a service request. The NFp verifies the integrity and claims in the access token and, if successful, executes the requested service for the NFc and generates a service response to the NFc.

[0108] 3GPP TR 33.875 (vl.6.0) describes a "Study on enhanced security aspects of the 5G Service Based Architecture (SBA)". One issue (called “Key Issue #3”) addressed by this study is service access in "Subscribe / Notify" scenarios (e.g., as shown in Figures 3-5 above), particularly the risk that an NFp may send a notification (or notify) message to an unauthorized NFc if the notification uniform resource identifier (URI) in the subscribe request is not authorized.

[0109] The service consumer NF can use binding to indicate suitable service consumer NF instance(s) for notification target instance selection, reselection and routing of subsequent notification requests associated with a specific notification subscription. Binding indication needs to be stored by the service producer NF and may also be used later if the service consumer NF starts acting as service producer NF, so that service requests can be sent to this service producer NF.

[0110] Similarly, binding can be used to indicate suitable target service producer NF instance(s) for an NF service instance selection, reselection, and routing of subsequent requests associated with a specific service producer NF resource (context) and NF service. Binding allows the service producer NF to indicate to the service consumer NF if a particular context should be bound to an NF service instance, NF instance, NF service set or NF set. Binding indication needs to be stored by the service consumer NF. Binding indications are further described in 3GPP TS 23.501 (vl7.0.0), including sections 3.1 and 6.3.1.

[0111] Additionally, Routing Binding Indication is information included in a request or notification that can be used for discovery and associated selection of a suitable target. Routing binding indication has similar syntax as a binding indication, but it has different purpose. Routing binding indication provides the receiver (i.e., an SCP) with information enabling to route an HTTP request to an HTTP server that can serve the request. Routing binding indication is not stored by the receiver. Routing binding indications are further described in 3GPP TS 23.501 (vl7.0.0), including sections 3.1, 6.3.1.0, and 7.1.2.

[0112] For direct communication, a service producer NF selects a target for the related notifications using the notification endpoint received in the subscription request. If the notification endpoint included in the subscription is not reachable, the received Binding Indication is used to discover an alternative notification endpoint. For indirect communication, the service producer NF includes the notification endpoint received in the subscription and may include a Routing Binding Indication with the same contents as the received Binding Indication. If the notification endpoint included in the subscription is not reachable, the SCP selects the target for the related notifications using the received Routing Binding Indication.

[0113] If the notification endpoint included in the explicit or implicit subscription is not reachable, the consumer NF Set information received in Binding Indication or Routing Binding Indication is used to discover an alternative notification endpoint. In general, an NF Set is a group of interchangeable NF instances of the same type, supporting the same services and the same Network Slice(s). The NF instances in the same NF Set may be geographically distributed but have access to the same context data.

[0114] Figure 7 is a flow diagram of an exemplary procedure for a service consumer NF (NFc, 710) to obtain an access token for subscribing to notifications from a service producer NF (NFp, e.g., 610 in Figure 6A).

[0115] In operation 1, the NFc requests an access token from the NRF using the Nnrf AccessToken Get Request service operation. The request includes the NF type of the NFc and requested “scope” including expected NF service name(s) and NF type(s). The request also includes “notification URI” since the operation semantics of the requested service type is "subscribe / notify". NRF may verify whether the notification URI in the access token request match the corresponding information in the NFc’s public key certificate or the NFc’s NF profile in the NRF. In addition, NRF may verify whether the notification URI corresponds to a location with the same address as indicated by the FQDN or IP address registered for NFc in NRF.

[0116] Additionally, the NRF checks whether the NFc is authorized to access the requested services by subscription / notification. When the NFc is authorized, the NRF generates an access token with appropriate claims that include the “notification URI” provided by the NFc and sends the access token to NFc using the Nnrf AccessToken Get Response service operation. The NFc can then send the received access token to the NFp in a subscription request, such as shown in Figures 3-5 above. The NFp verifies the integrity and claims in the access token and, if successful, subscribes the NFp for notifications in accordance with the request. Nevertheless, even if an NFc is authorized to receive notifications for a subscription, it is unclear how the NFc can be sure that a notification is coming from a notifier NF that is authorized to send notifications. For example, a notification URI can obtained by an unauthorized third party, who could use it to send false notifications to provoke NFc actions with undesirable consequences.

[0117] As a more specific example, “deregCallbackUri” is a URI provided by AMF to receive (implicitly subscribed) notifications on deregistration of a UE, and is associated with unique information within AMF that identifies the UE to be deregistered. Thus, any NF that obtains this URI can use it to deregister the associated UE from AMF, such that the UE would be unable to access some or all of the services in the 5G network.

[0118] Embodiments of the present disclosure address these and other problems, issues, and / or difficulties by providing novel, flexible, and efficient techniques whereby an authorization server (e.g., NRF) can perform token-based authorization for notifications, including how to determine that a prospective notifier NF is authorized and how subscriber and / or notification receiver NFs can assist NRF with authorization. Once a notifier NF obtains an access token, it can provide the access token to the subscriber / receiver NF together with an associated notification. This information in the access token can be used by a subscriber / receiver NF to ensure that it receives notification messages from authorized senders (i.e., notifier NFs). This can improve security of the 5G SBA by mitigating various attack scenarios, including the one summarized above.

[0119] Embodiments will be described below in the context of procedures involving four entities: NF that subscribes to notifications (“subscriber NF”), NF that receives notifications based on the subscription (“receiver NF”), NF that provides notifications based on the subscription (“notifier NF”), and authorization server (e.g., NRF). In some embodiments, subscriber NF and receiver NF may be identical (e.g., as shown in Figure 3 above). In other embodiments, subscriber NF and receiver NF may be different NFs (e.g., as shown in Figures 4-5 above).

[0120] Subscriber NF and / or receiver NF may register NF profile(s) in NRF, including notification authorization information. This notification authorization information may include Notification Type (e.g., Deregistration Notification, P-CSCF Restoration Notification, Data Restoration Notification, etc.) and information about the notifier NF (e.g., NF type, NF (service) instance or list, NF (service) set, etc.). For example, the notification authorization information could be called allowedNotificationperNfType or allowedNotificationperNfinstances.

[0121] In the delegated subscribe-notify case (e.g., such as shown in Figure 4), the first step of the subscribe-notify interaction may be a service request by the receiver NF to the subscriber NF that triggers the subscriber NF to subscribe on behalf of the receiver NF. This request may contain the callback (or notification) URI used by the receiver NF to receive the notifications.

[0122] The subscriber NF sends a request message to the notifier NF, with an explicit or implicit subscription. In some embodiments, this request includes the NF type and / or an NF set of the receiver NF. In some embodiments, this request includes the Notification Type, which may be associated with a notification callback reference URI. In some embodiments, the information about the notifier NF (e.g., NF type, NF (service) instance or list, NF (service) set, etc.) may be associated with a notification callback reference URI. The following is an example notification callback reference URI according to these embodiments:

[0123] URI = scheme " / / " host [ port ] / [Notification Type] / [notifier NF info] / path

[0124] In the case of a default notification subscription, the notifier NF performs NF discovery towards NRF to get the callback URI and other information about the receiver NF to be used in a request for an access token for notifications (described below). When the notification subscription is by an intermediate NF on behalf of the receiver NF, the notifier NF gets the callback URI and other information about the receiver NF from the intermediate NF who sends the subscription request.

[0125] The notifier NF then sends an access token request to the NRF acting as authorization server. In some embodiments, the access token request includes an indication that the request is for sending notifications. In other embodiments, the access token request is sent to a dedicated NRF URI that is specific to a notification authorization service (e.g., access token service URI) of the NRF. In other embodiments, the access token request includes the NF type and / or an NF set of the receiver NF. In some embodiments, the access token request may include the Notification Type, notification callback reference URI, subscription ID, and / or subscription lifetime (if available for an explicit subscription).

[0126] Upon receiving the request, the NRF (authorization server) checks whether the notifier NF is authorized, e.g., based on the previously registered NF profile of subscriber / receiver NF. If authorized, the NRF sends an access token to the notifier NF.

[0127] In some embodiments, the access token includes an indication that it is for sending notifications. In some embodiments, the access token contains the NF type and / or an NF set of the receiver NF, an NF set of the notifier NF, Notification Type, notification callback reference URI, and / or subscription ID. The access token may include a lifetime, which can be determined by the NRF based on the lifetime of the corresponding subscription (if available, as mentioned above).

[0128] At some point after receiving the access token, the notifier NF sends a notification to the receiver NF according to the earlier subscription. The notification contains the received access token. In some embodiments, the receiver NF checks whether it is the intended recipient of this notification based on subscription ID, NF type of the receiver NF, and / or NF set of the receiver NF in the access token. In some embodiments, the receiver NF checks for consistency between NF type of the receiver NF, NF set of the receiver NF, and / or notification callback reference URI in the access token.

[0129] The embodiments described above will be further illustrated by Figures 8-11, which show signaling diagrams of various procedures for obtaining an access token for sending notifications, according to various embodiments of the present disclosure. Although the operations shown in Figures 8-11 are given numerical labels, this is intended to facilitate the following description rather than to require any particular order of the operations, unless expressly stated otherwise.

[0130] Figure 8 shows a signaling diagram between a subscriber NF (810), an authorization server (820), a notifier NF (830), and a receiver NF (840), according to some embodiments. In the scenario shown in Figure 8, the subscriber NF subscribes for notifications on behalf of the receiver NF.

[0131] In operation 1, the subscriber NF (e.g., AMF) sends a subscription request to the notifier NF (e.g., UDM). In operation 2, the notifier NF sends a request for an access token to the authorization server (e.g., NRF). The request indicates that it is for notifications, and optionally includes the NF type and / or NF set of the receiver NF. In operation 3, after verifying that the notifier NF is authorized to send notifications to the receiver NF (e.g., based on previously registered NF profile), the authorization server sends a response with an access token that includes the information received from the notifier NF. In operation 4, the notifier NF sends the receiver NF a notification that includes, or is together with, the access token. Although not shown, the receiver NF can verify the authorization of the notifier NF based on the received access token.

[0132] Figure 9 shows a signaling diagram between a subscriber / receiver NF (910), an authorization server (920), and a notifier NF (930), according to other embodiments. In the scenario shown in Figure 9, the subscriber NF and the receiver NF are identical.

[0133] In operation 0, the subscriber / receiver NF registers its NF profile in the authorization server. The NF profile includes a callback URI schema for notifications and allowed NF information, which identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the subscriber / receiver NF. In operation 1, the subscriber / receiver NF sends a subscription request to the notifier NF. The subscription request may include an indication of whether it is implicit or explicit, as well as a callback (or notification) URI associated with the receiver NF. Optionally, the subscription request includes a callback URI schema for notifications, e.g., as sent to the authorization server in operation 0.

[0134] In operation 2, the notifier NF sends a request for an access token to the authorization server. The request includes the callback URI and optionally (i.e., if received in operation 1) the callback URI schema for notifications. In operation 3, after verifying that the notifier NF is authorized to send notifications to the receiver NF (e.g., based on NF profile information registered in operation 0), the authorization server sends a response with an access token that includes the callback URI and the callback URI schema for notifications. In operation 4, the notifier NF sends the subscriber / receiver NF a notification that includes, or is together with, the access token.

[0135] Figure 10 shows a signaling diagram between a subscriber NF (1010), an authorization server (1020), a notifier NF (1030), and a receiver NF (1040), according to other embodiments. In the scenario shown in Figure 10, the subscriber NF subscribes for notifications on behalf of the receiver NF.

[0136] In operation 0, the receiver NF registers its NF profile in the authorization server. The NF profile includes a callback URI schema for notifications and allowed NF information, which identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF. In operation la, the receiver NF sends a service request to the subscriber NF, indicating that the subscriber NF should subscribe to notifications on behalf of the receiver NF. The service request includes a callback (or notification) URI associated with the receiver NF. Optionally, the service request includes a callback URI schema for notifications.

[0137] In operation 1, in response to the service request, the subscriber NF sends a subscription request to the notifier NF. The subscription request may include an indication of whether it is implicit or explicit, as well as the callback URI associated with the receiver NF that was received in operation la. Optionally, the subscription request includes the callback URI schema for notifications, e.g., if received in operation la.

[0138] In operation 2, the notifier NF sends a request for an access token to the authorization server. The request includes the callback NRI and optionally (i.e., if received in operation 1) the callback URI schema for notifications. In operation 3, after verifying that the notifier NF is authorized to send notifications to the receiver NF (e.g., based on NF profile information registered in operation 0), the authorization server sends a response with an access token that includes the callback URI and the callback URI schema for notifications. In operation 4, the notifier NF sends the receiver NF a notification that includes, or is together with, the access token.

[0139] Figure 11 shows a signaling diagram between a subscriber / receiver NF (1110), an authorization server (1120), and a notifier NF (1130), according to other embodiments. In the scenario shown in Figure 11, the subscriber NF and the receiver NF are identical.

[0140] In operation 0, the subscriber / receiver NF registers its NF profile in the authorization server. The NF profile includes a callback URI schema for notifications and allowed NF information, which identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the subscriber / receiver NF. In operation la, the notifier NF sends a discovery request to the authorization server. The discovery request may indicate a notification type that the notifier NF provides. In operation lb, after identifying that the subscriber / receiver NF is registered for this notification type, the authorization server sends the notifier NF a discovery response that includes a callback (or notification) URI associated with the subscriber / receiver NF. Optionally, the discovery response includes a callback URI schema for notifications, e.g., as registered with the authorization server in operation 0. Operations 2-4 are identical to respective operations 2-4 of Figure 9, described above.

[0141] As mentioned above, NFc’s and / or NFp’s may be part of an NF set. Figure 12 shows an arrangement of a first NF set (1210) of NFc-1 (1211) and NFc-2 (1212) and a second NF set (1220) of NFp-1 (1221) and NFp-2 (1222). In this arrangement, NFc-1 sends a subscription request to NFp-1. The subscription request may include a first token (“token#l”) for the NFp service, indicating that NFc-1 is authorized to subscribe for notifications. The first token can be obtained, for example, using the procedure shown in Figure 7. The first token can include an identification of the second NF set that includes NFp-1 and NFp-2, indicating that NFc-1 is authorized to subscribe for notifications from the second NF set.

[0142] UE session data and NFc subscription information is shared within the second NF set. In this manner, NFp-2 is able to send a notification pertaining to this subscription to NFc-2, even though NFc-1 sent the subscription to NFp-1. In this notification, NFp-2 includes a second token (“token#2”) indicating that NFp-2 is authorized to provide notifications. The second token can be obtained according to any of the embodiments illustrated in Figures 8-11. The second token can include an identification of the second NF set that includes NFp-1 and NFp-2 (i.e., valid notifiers) and an identification of the first NF set that includes NFc-1 and NFc-2 (i.e., receivers).

[0143] The embodiments described above can be further illustrated with reference to Figures 13- 16, which depict exemplary methods e.g., procedures) for a receiver NF, a notifier NF, an authorization server, and a subscriber NF, respectively. Put differently, various features of the operations described below correspond to various embodiments described above. The exemplary methods shown in Figures 13-16 can be used cooperatively (e.g., with each other and with other procedures described herein) to provide benefits, advantages, and / or solutions to problems described herein. Although the exemplary methods are illustrated in Figures 13-16 by specific blocks in particular orders, the operations corresponding to the blocks can be performed in different orders than shown and can be combined and / or divided into blocks and / or operations having different functionality than shown. Optional blocks and / or operations are indicated by dashed lines. More specifically, Figure 13 illustrates an exemplary method e.g., procedure) receiver NF arranged to receive notifications from notifier NFs of a communication network (e.g., 5GC), according to various embodiments of the present disclosure. The exemplary method shown in Figure 13 can be performed by various NFs (or network equipment implementing such NFs) as described elsewhere herein.

[0144] The exemplary method can include the operations of block 1320, where the receiver NF can send, to a first NF of the communication network, a first message related to a subscription for receiving notifications from a notifier NF of the communication network. The exemplary method can also include the operations of block 1330, where the receiver NF can receive, from the notifier NF, a notification in accordance with the subscription, wherein the notification includes or is received in association with a first access token indicating that the notifier NF is authorized to send the notification.

[0145] In some embodiments, the first NF is the notifier NF and the first message is a subscription request for notifications from the notifier NF. Figures 8-9 and 11 are examples of these embodiments. In other embodiments, the first NF is a subscriber NF different from the receiver NF and the first message is a service request indicating that the subscriber NF should subscribe to notifications on behalf of the receiver NF. Figure 10 is an example of these embodiments.

[0146] In some embodiments, the first message includes one or more of the following information:

[0147] • an indication of whether the subscription is implicit or explicit;

[0148] • an identifier of the subscription;

[0149] • a first validity duration (e.g., lifetime) associated with the subscription;

[0150] • a notification type associated with the subscription;

[0151] • a callback URI at which the receiver NF can receive the notifications;

[0152] • a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated;

[0153] • one or more of the following associated with the receiver NF: NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and

[0154] • one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

[0155] In some of these embodiments, the first access token includes one or more of the following information that is also included in the first message: the identifier of the subscription, the callback URI, the callback URI schema, and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances. In some variants of these embodiments, the exemplary method can also include the operations of block 1340, where the receiver NF can verify that it is the intended recipient of the notification based on the information included in both the first access token and the first message.

[0156] In some of these embodiments, the first validity duration associated with the subscription is included in first message and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity.

[0157] In some embodiments, the exemplary method can also include the operations of block 1310, where the receiver NF can register a NF profile of the receiver NF with an authorization server of the communication network. The registered NF profile includes one or more of the following: a callback URI schema, from which callback URIs for the receiver NF can be generated; and allowed NF information that identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF.

[0158] In some of these embodiments, the authorization server is an NRF, the receiver NF is an AMF, and / or the notifier NF is a UDM function.

[0159] In some embodiments, the first message includes a second access token indicating that the receiver NF is authorized to subscribe to the notifications from the notifier NF.

[0160] In addition, Figure 14 illustrates an exemplary method (e.g., procedure) for a notifier NF arranged to send notifications to receiver NFs in a communication network (e.g., 5GC), according to various embodiments of the present disclosure. The exemplary method shown in Figure 14 can be performed by various NFs (or network equipment implementing such NFs) as described elsewhere herein.

[0161] The exemplary method can include the operations of block 1420, where the notifier NF can receive, from a first NF of the communication network, a first message related to a subscription for a receiver NF to receive notifications from the notifier NF. The exemplary method can also include the operations of block 1430, where the notifier NF can send, to an authorization server of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to the receiver NF. The exemplary method can also include the operations of block 1440, where the notifier NF can receive from the authorization server a first access token in accordance with the access token request. The exemplary method can also include the operations of block 1450, where the notifier NF can send to the receiver NF a notification in accordance with the subscription request. The notification includes or is sent in association with the first access token. In some embodiments, the first message is a subscription request for notifications from the notifier NF and the first NF is the receiver NF or a subscriber NF authorized to subscribe to notifications on behalf of the receiver NF. Figures 8-10 are examples of these embodiments.

[0162] In other embodiments, the first NF is a subscriber NF different from the receiver NF and the first message is a service request indicating that the subscriber NF should subscribe to notifications on behalf of the receiver NF. Figure 10 is an example of these embodiments.

[0163] In other embodiments, the first NF is the authorization server and the exemplary method can also include the operations of block 1410, where the notifier NF send to the authorization server a discovery request to identify NFs of the communication network that are subscribed to notifications provided by the notifier NF. In such case, the first message is a discovery response received (e.g., in block 1420) in response to the discovery request.

[0164] In various embodiments, the first message can include any of the information described above in relation to receiver NF embodiments shown in Figure 13.

[0165] In some of these embodiments, the access token request includes an indication that the requested access token is for notifications and one or more of the following information that was included in the first message:

[0166] • the identifier of the subscription;

[0167] • the first validity duration (e.g., lifetime) associated with the subscription;

[0168] • the callback URI;

[0169] • the callback URI schema;

[0170] • the notification type associated with the subscription; and

[0171] • one or more of the following associated with the receiver NF: NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0172] In some variants of these embodiments, the first access token one or more of the following information that was included in the first message and the access token request:

[0173] • the identifier of the subscription;

[0174] • the callback URI;

[0175] • the callback URI schema; and

[0176] • one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0177] In some variants of these embodiments, the first validity duration associated with the subscription is included in the first message and the access token request, and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity. In some embodiments, the first message includes a second access token indicating that the receiver NF is authorized to subscribe to the notifications from the notifier NF. In some embodiments, the access token request is sent to a URI that is specific to a notification authorization service of the authorization server. In some embodiments, the authorization server is an NRF, the receiver NF is an AMF, and / or the notifier NF is a UDM function.

[0178] In addition, Figure 15 illustrates an exemplary method (e.g., procedure) for an authorization server of a communication network (e.g., 5GC), according to various embodiments of the present disclosure. The exemplary method shown in Figure 15 can be performed by an authorization server (e.g., NRF or network equipment implementing the same) as described elsewhere herein.

[0179] The exemplary method can include the operations of block 1550, where the authorization server can receive, from a notifier NF of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to a receiver NF of the communication network. The exemplary method can also include the operations of block 1560, where the authorization server can authorize the access token request based on an NF profile for the receiver NF that is registered in the authorization server. The exemplary method can also include the operations of block 1570, where based on authorizing the access token request, the authorization server can send to the notifier NF a first access token in accordance with the access token request.

[0180] In some embodiments, the access token request includes one or more of the following information:

[0181] • an indication that the requested access token is for notifications;

[0182] • an identifier of the receiver NF’s subscription to notifications from the notifier NF;

[0183] • a first validity duration (e.g., lifetime) associated with the subscription;

[0184] • a callback URI, at which the receiver NF can receive notifications related to the subscription;

[0185] • a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated;

[0186] • a notification type associated with the subscription; and

[0187] • one or more of the following associated with the receiver NF: NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0188] In some of these embodiments, the first access token includes one or more of the following information that is included in the access token request:

[0189] • the identifier of the subscription;

[0190] • the callback URI; • the callback URI schema; and

[0191] • one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0192] In some of these embodiments, the first validity duration associated with the subscription is included in the access token request and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity.

[0193] In some of these embodiments, the exemplary method can also include the following operations, labelled with corresponding block numbers:

[0194] • (1520) receiving from the notifier NF a discovery request to identify NFs of the communication network that are subscribed to notifications provided by the notifier NF;

[0195] • (1530) identifying the receiver NF based on the registered NF profile and the discovery request; and

[0196] • (1540) sending to the notifier NF a discovery response that identifies the receiver NF and includes at least a portion of the information received in the access token request.

[0197] In some embodiments, the exemplary method can also include the operations of block 1510, where the authorization server can register the NF profile of the receiver NF. The registered NF profile includes one or more of the following:

[0198] • a callback URI schema, from which callback URIs for the receiver NF can be generated; and

[0199] • allowed NF information that identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF.

[0200] In some of these embodiments, authorizing the access token request in block 1560 is based on detecting one or more of the following:

[0201] • a match or correspondence between the allowed NF information in the registered NF profile and one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances; and

[0202] • a match or correspondence between the callback URI schema in the registered NF profile and a callback URI schema in the access token request.

[0203] In some embodiments wherein the access token request is received at a URI that is specific to a notification authorization service of the authorization server. In some embodiments, the authorization server is an NRF, the receiver NF is an AMF, and / or the notifier NF is a UDM function. In addition, Figure 16 illustrates an exemplary method e.g., procedure) for a subscriber NF arranged to subscribe to notifications from a notifier NF of a communication network on behalf of a receiver NF of the communication network (e.g., 5GC), according to various embodiments of the present disclosure. The exemplary method shown in Figure 16 can be performed by various NFs (or network equipment implementing such NF s) as described elsewhere herein.

[0204] The exemplary method can include the operations of block 1610, where the subscriber NF can receive, from the receiver NF, a service request indicating that the subscriber NF should subscribe to notifications from the notifier NF on behalf of the receiver NF. The exemplary method can also include the operations of block 1620, where the subscriber NF can send to the notifier NF a subscription request in accordance with the service request.

[0205] In some embodiments, the service request includes one or more of the following information:

[0206] • an identifier of the receiver NF’s subscription to notifications from the notifier NF;

[0207] • a first validity duration (e.g., lifetime) associated with the subscription;

[0208] • a callback URI, at which the receiver NF can receive notifications related to the subscription;

[0209] • a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated;

[0210] • a notification type to which the receiver NF wants to subscribe;

[0211] • one or more of the following associated with the receiver NF: NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and

[0212] • one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

[0213] In some of these embodiments, the subscription request includes the information included in the service request and an indication of whether the subscription is implicit or explicit.

[0214] In some embodiments, the subscriber NF is a first AMF, the notifier NF is a UDM function, and the receiver NF is a second AMF different than the first AMF.

[0215] 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.

[0216] Figure 17 shows an example of a communication system 1700 in accordance with some embodiments. In this example, communication system 1700 includes telecommunication network 1702 that includes an access network 1704 (e.g., RAN) and a core network 1706, which includes one or more core network nodes 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 3 GPP access node or non-3GPP access point. 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.

[0217] 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.

[0218] 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.

[0219] 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 or more 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 may be implemented with various combinations of 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 the 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).

[0220] For example, one or more core network nodes 1708 can be configured to perform operations attributed to various NFs in the descriptions herein of various methods or procedures. As a more specific example, the one or more core network nodes 1708 can be configured to perform operations attributed to a receiver NF (e.g., AMF), a notifier NF (e.g., UDM), an authorization server (e.g., NRF), and a subscriber NF (e.g., AMF).

[0221] 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.

[0222] 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.

[0223] In some examples, telecommunication network 1702 is a cellular network that implements 3 GPP 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.

[0224] 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 more of Wi-Fi, NR, and LTE, e.g., 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).

[0225] 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 data collector that acts as temporary storage for UE data and, 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 in if one or more of the UEs are low energy loT devices.

[0226] Hub 1714 may have a constant / persistent or intermittent connection to the network node 1710b. Hub 1714 may also allow for a different communication scheme and / or schedule between hub 1714 and UEs (e.g., 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 / from the UEs from / to the network node 1710b. In other embodiments, hub 1714 may be a non-dedicated hub - that is, a device which can route communications between the UEs and network node 1710b, but which also can operate as a communication start and / or end point for certain data channels. Figure 18 shows a network node 1800 in accordance with some embodiments. Examples of network nodes include, but are not limited to, access points (e.g., radio access points) and base stations (e.g., radio base stations, Node Bs, eNBs, gNBs, etc.).

[0227] 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 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).

[0228] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast 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).

[0229] For example, one or more network nodes 1800 can be configured to perform operations attributed to various NFs in the descriptions herein of various methods or procedures. As a more specific example, the one or more network nodes 1800 can be configured to perform operations attributed to a receiver NF (e.g., AMF), a notifier NF (e.g., UDM), an authorization server (e.g., NRF), and a subscriber NF (e.g., AMF).

[0230] Network node 1800 includes 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.

[0231] 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.

[0232] In some embodiments, processing circuitry 1802 includes a system on a chip (SOC). In some embodiments, processing circuitry 1802 includes one or more of radio frequency (RF) transceiver circuitry 1812 and baseband processing circuitry 1814. In some embodiments, RF transceiver circuitry 1812 and 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 baseband processing circuitry 1814 may be on the same chip or set of chips, boards, or units.

[0233] 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 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 (collectively denoted computer program product 1804a) capable of being executed by processing circuitry 1802 and utilized by network node 1800. Memory 1804 may be used to store any calculations made by processing circuitry 1802 and / or any data received via communication interface 1806. In some embodiments, processing circuitry 1802 and memory 1804 is integrated.

[0234] 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 processing circuitry 1802. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0235] In certain alternative embodiments, network node 1800 does not include separate radio front-end circuitry 1818, instead, 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).

[0236] 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.

[0237] Antenna 1810, communication interface 1806, and / or 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 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. 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.

[0238] 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.

[0239] 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.

[0240] 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.

[0241] For example, various NFs (or portions thereof) described herein in relation to other figures can be implemented as virtual network functions 1902 in virtualization environment 1900. As a more specific example, a receiver NF (e.g., AMF), a notifier NF (e.g., UDM), an authorization server (e.g., NRF), and / or a subscriber NF (e.g., AMF) can be implemented as virtual network functions 1902 in virtualization environment 1900.

[0242] Hardware 1904 includes processing circuitry, memory that stores software and / or instructions (collectively denoted computer program product 1904a) 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.

[0243] 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 made in different ways. 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.

[0244] 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 hardware 1904 and corresponds to application 1902.

[0245] 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 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 control system 1912 which may alternatively be used for communication between hardware nodes and radio units.

[0246] 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 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.

[0247] 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.

[0248] 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 carrying out 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 one or more embodiments of the present disclosure.

[0249] 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.

[0250] 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.

[0251] 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. Further, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it is explicitly incorporated herein in its entirety. All publications referenced are incorporated herein by reference in their entireties.

[0252] Embodiments of the techniques and apparatus described herein also include, but are not limited to, the following enumerated examples:

[0253] Al . A method performed by a receiver network function (NF) arranged to receive notifications from notifier NFs of a communication network, the method comprising: sending, to a first NF of the communication network, a first message related to a subscription for receiving notifications from a notifier NF of the communication network; and receiving, from the notifier NF, a notification in accordance with the subscription, wherein the notification includes or is received in association with a first access token indicating that the notifier NF is authorized to send the notification.

[0254] A2. The method of embodiment Al, wherein the first NF is the notifier NF and the first message is a subscription request for notifications from the notifier NF. A3. The method of embodiment Al, wherein the first NF is a subscriber NF different from the receiver NF, and the first message is a service request indicating that the subscriber NF should subscribe to notifications on behalf of the receiver NF.

[0255] A4. The method of any of embodiments A1-A3, wherein the first message includes one or more of the following information: an indication of whether the subscription is implicit or explicit; an identifier of the subscription; a first validity duration associated with the subscription; a notification type associated with the subscription; a callback uniform resource identifier (URI) at which the receiver NF can receive the notifications; a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated; one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

[0256] A5. The method of embodiment A4, wherein the first access token includes one or more of the following information that is also included in the first message: the identifier of the subscription; the callback URI; the callback URI schema; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0257] A6. The method of embodiment A5, further comprising verifying that the receiver NF is the intended recipient of the notification based on the information included in both the first access token and the first message.

[0258] A7. The method of any of embodiments A4-A6, wherein: the first validity duration associated with the subscription is included in first message; and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity.

[0259] A8. The method of any of embodiments A1-A7, further comprising registering a NF profile of the receiver NF with an authorization server of the communication network, wherein the registered NF profile includes one or more of the following: a callback uniform resource identifier (URI) schema, from which callback URIs for the receiver NF can be generated; and allowed NF information that identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF.

[0260] A9. The method of embodiment A8, wherein one or more of the following applies: the authorization server is a network repository function (NRF), the receiver NF is an access and mobility management function (AMF), and the notifier NF is a unified data management (UDM) function.

[0261] A10. The method of any of embodiments A1-A9, wherein the first message includes a second access token indicating that the receiver NF is authorized to subscribe to the notifications from the notifier NF.

[0262] Bl. A method performed by a notifier network function (NF) arranged to send notifications to receiver NFs in a communication network, the method comprising: receiving, from a first NF of the communication network, a first message related to a subscription for a receiver NF to receive notifications from the notifier NF; sending, to an authorization server of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to the receiver NF; receiving from the authorization server a first access token in accordance with the access token request; and sending, to the receiver NF, a notification in accordance with the subscription request, wherein the notification includes or is sent in association with the first access token. B2. The method of embodiment Bl, wherein: the first message is a subscription request for notifications from the notifier NF; and the first NF is the receiver NF or a subscriber NF authorized to subscribe to notifications on behalf of the receiver NF.

[0263] B3. The method of embodiment Bl, wherein: the first NF is the authorization server; the method further comprises sending to the authorization server a discovery request to identify NFs of the communication network that are subscribed to notifications provided by the notifier NF; and the first message is a discovery response received in response to the discovery request.

[0264] B4. The method of any of embodiments B1-B3, wherein the first message includes one or more of the following: an indication of whether the subscription is implicit or explicit; an identifier of the subscription; a first validity duration associated with the subscription; a notification type associated with the subscription; a callback uniform resource identifier (URI) at which the receiver NF can receive the notifications; a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated; one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

[0265] B5. The method of embodiment B4, wherein the access token request includes an indication that the requested access token is for notifications and one or more of the following information that was included in the first message: the identifier of the subscription; the first validity duration associated with the subscription; the callback URI; the callback URI schema; the notification type associated with the subscription; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0266] B6. The method of embodiment B5, wherein the first access token includes one or more of the following information that was included in the first message and the access token request: the identifier of the subscription; the callback URI; the callback URI schema; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0267] B7. The method of any of embodiments B5-B6, wherein: the first validity duration associated with the subscription is included in the first message and the access token request; and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity.

[0268] B8. The method of any of embodiments B1-B7, wherein the first message includes a second access token indicating that the receiver NF is authorized to subscribe to the notifications from the notifier NF.

[0269] B9. The method of any of embodiments B1-B8, wherein the access token request is sent to a uniform resource identifier (URI) that is specific to a notification authorization service of the authorization server.

[0270] BIO. The method of any of embodiments B1-B9, wherein one or more of the following applies: the authorization server is a network repository function (NRF), the receiver NF is an access and mobility management function (AMF), and the notifier NF is a unified data management (UDM) function.

[0271] Cl . A method performed by an authorization server of a communication network, the method comprising: receiving, from a notifier network function (NF) of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to a receiver NF of the communication network; authorizing the access token request based on an NF profile for the receiver NF that is registered in the authorization server; and based on authorizing the access token request, sending to the notifier NF a first access token in accordance with the access token request.

[0272] C2. The method of embodiment Cl, wherein the access token request includes one or more of the following information: an indication that the requested access token is for notifications; an identifier of the receiver NF’s subscription to notifications from the notifier NF; a first validity duration associated with the subscription; a callback uniform resource identifier (URI), at which the receiver NF can receive notifications related to the subscription; a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated; a notification type associated with the subscription; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0273] C3. The method of embodiment C2, wherein the first access token includes one or more of the following information that is included in the access token request: the identifier of the subscription; the callback URI; the callback URI schema; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

[0274] C4. The method of any of embodiments C2-C3, wherein: the first validity duration associated with the subscription is included in the access token request; and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity.

[0275] C5. The method of any of embodiments C2-C4, further comprising: receiving from the notifier NF a discovery request to identify NFs of the communication network that are subscribed to notifications provided by the notifier NF; identifying the receiver NF based on the registered NF profile and the discovery request; and sending to the notifier NF a discovery response that identifies the receiver NF and includes at least a portion of the information received in the access token request.

[0276] C6. The method of any of embodiments C1-C5, further comprising registering the NF profile of the receiver NF, wherein the registered NF profile includes one or more of the following: a callback uniform resource identifier (URI) schema, from which callback URIs for the receiver NF can be generated; and allowed NF information that identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF.

[0277] C7. The method of embodiment C6, where authorizing the access token request is based on detecting one or more of the following: a match or correspondence between the allowed NF information in the registered NF profile and one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances; and a match or correspondence between the callback URI schema in the registered NF profile and a callback URI schema in the access token request

[0278] C8. The method of any of embodiments C1-C7, wherein the access token request is received at a uniform resource identifier (URI) that is specific to a notification authorization service of the authorization server.

[0279] C9. The method of any of embodiments C1-C8, wherein one or more of the following applies: the authorization server is a network repository function (NRF), the receiver NF is an access and mobility management function (AMF), and the notifier NF is a unified data management (UDM) function. DI . A method performed by a subscriber network function (NF) arranged to subscribe to notifications from a notifier NF of a communication network on behalf of a receiver NF of the communication network, the method comprising: receiving, from the receiver NF, a service request indicating that the subscriber NF should subscribe to notifications from the notifier NF on behalf of the receiver NF; and sending, to the notifier NF, a subscription request in accordance with the service request.

[0280] D2. The method of embodiment DI, wherein the service request includes one or more of the following information: an identifier of the receiver NF’s subscription to notifications from the notifier NF; a first validity duration associated with the subscription; a callback uniform resource identifier (URI), at which the receiver NF can receive notifications related to the subscription; a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated; a notification type to which the receiver NF wants to subscribe; one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

[0281] D3. The method of embodiment D2, wherein the subscription request includes the information included in the service request and an indication of whether the subscription is implicit or explicit.

[0282] D4. The method of any of embodiments D1-D3, wherein one or more of the following applies: the subscriber NF is a first access and mobility management function (AMF), the notifier NF is a unified data management (UDM) function, and the receiver NF is a second AMF different than the first AMF.

[0283] El . A receiver network function (NF) arranged to receive notifications from notifier NFs of a communication network, the receiver NF comprising: communication interface circuitry configured to communicate with the notifier NFs and with an authorization server of the communication network; and processing circuitry operably 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 Al- A10.

[0284] E2. A receiver network function (NF) arranged to receive notifications from notifier NFs of a communication network, the receiver NF being further arranged to perform operations corresponding to any of the methods of embodiments A1-A10.

[0285] E3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry associated with receiver network function (NF) arranged to receive notifications from notifier NFs of a communication network, configure the receiver NF to perform operations corresponding to any of the methods of embodiments Al- A10.

[0286] E4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry associated with receiver network function (NF) arranged to receive notifications from notifier NFs of a communication network, configure the receiver NF to perform operations corresponding to any of the methods of embodiments A1-A10.

[0287] Fl. A notifier network function (NF) arranged to send notifications to receiver NF s in a communication network, the notifier NF comprising: communication interface circuitry configured to communicate with the receiver NFs and with an authorization server of the communication network; and processing circuitry operably 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 Bl- B10.

[0288] F2. A notifier network function (NF) arranged to send notifications to receiver NFs in a communication network, the notifier NF being further arranged to perform operations corresponding to any of the methods of embodiments Bl -BIO. F3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry associated with a notifier network function (NF) arranged to send notifications to receiver NFs in a communication network, configure the notifier NF to perform operations corresponding to any of the methods of embodiments Bl -BIO.

[0289] F4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry associated with a notifier network function (NF) arranged to send notifications to receiver NFs in a communication network, configure the notifier NF to perform operations corresponding to any of the methods of embodiments Bl -BIO.

[0290] G1. An authorization server of a communication network, the authorization server comprising: communication interface circuitry configured to communicate with receiver network functions (NFs) and notifier NFs of the communication network; and processing circuitry operably 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 Cl- C9.

[0291] G2. An authorization server of a communication network, the authorization server being arranged to perform operations corresponding to any of the methods of embodiments C1-C9.

[0292] G3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry associated with an authorization server of a communication network, configure the authorization server to perform operations corresponding to any of the methods of embodiments C1-C9.

[0293] G4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry associated with an authorization server of a communication network, configure the authorization server to perform operations corresponding to any of the methods of embodiments C1-C9.

[0294] Hl . A subscriber network function (NF) arranged to subscribe to notifications from a notifier NF of a communication network on behalf of a receiver NF of the communication network, the subscriber NF comprising: communication interface circuitry configured to communicate with the notifier NF and with the receiver NF; and processing circuitry operably 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 Dl- D4.

[0295] H2. A subscriber network function (NF) arranged to subscribe to notifications from a notifier NF of a communication network on behalf of a receiver NF of the communication network, the subscriber NF being further arranged to perform operations corresponding to any of the methods of embodiments D1-D4.

[0296] H3. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry associated with a notifier network function (NF) arranged to send notifications to receiver NFs in a communication network, configure the notifier NF to perform operations corresponding to any of the methods of embodiments D1-D4.

[0297] H4. A computer program product comprising computer-executable instructions that, when executed by processing circuitry associated with a notifier network function (NF) arranged to send notifications to receiver NFs in a communication network, configure the notifier NF to perform operations corresponding to any of the methods of embodiments D1-D4.

Claims

CLAIMS1. A method performed by a receiver network function, NF, arranged to receive notifications from notifier NFs of a communication network, the method comprising: sending (1320), to a first NF of the communication network, a first message related to a subscription for receiving notifications from a notifier NF of the communication network; and receiving (1330), from the notifier NF, a notification in accordance with the subscription, wherein the notification includes or is received in association with a first access token indicating that the notifier NF is authorized to send the notification.

2. The method of claim 1, wherein the first NF is the notifier NF and the first message is a subscription request for notifications from the notifier NF.

3. The method of claim 1, wherein the first NF is a subscriber NF different from the receiver NF, and the first message is a service request indicating that the subscriber NF should subscribe to notifications on behalf of the receiver NF.

4. The method of any of claims 1-3, wherein the first message includes one or more of the following information: an indication of whether the subscription is implicit or explicit; an identifier of the subscription; a first validity duration associated with the subscription; a notification type associated with the subscription; a callback uniform resource identifier, URI, at which the receiver NF can receive the notifications; a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated; one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

5. The method of claim 4, wherein the first access token includes one or more of the following information that is also included in the first message: the identifier of the subscription; the callback URI; the callback URI schema; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

6. The method of claim 5, further comprising verifying (1340) that the receiver NF is the intended recipient of the notification based on the information included in both the first access token and the first message.

7. The method of any of claims 4-6, wherein: the first validity duration associated with the subscription is included in first message; and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity.

8. The method of any of claims 1-7, further comprising registering (1310) a NF profile of the receiver NF with an authorization server of the communication network, wherein the registered NF profile includes one or more of the following: a callback uniform resource identifier, URI, schema, from which callback URIs for the receiver NF can be generated; and allowed NF information that identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF.

9. The method of claim 8, wherein one or more of the following applies: the authorization server is a network repository function, NRF; the receiver NF is an access and mobility management function, AMF; and the notifier NF is a unified data management, UDM, function.

10. The method of any of claims 1-9, wherein the first message includes a second access token indicating that the receiver NF is authorized to subscribe to the notifications from the notifier NF.

11. A method performed by a notifier network function, NF, arranged to send notifications to receiver NFs in a communication network, the method comprising: receiving (1420), from a first NF of the communication network, a first message related to a subscription for a receiver NF to receive notifications from the notifier NF; sending (1430), to an authorization server of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to the receiver NF; receiving (1440) from the authorization server a first access token in accordance with the access token request; and sending (1450), to the receiver NF, a notification in accordance with the subscription request, wherein the notification includes or is sent in association with the first access token.

12. The method of claim 11, wherein: the first message is a subscription request for notifications from the notifier NF; and the first NF is the receiver NF or a subscriber NF authorized to subscribe to notifications on behalf of the receiver NF.

13. The method of claim 11, wherein: the first NF is the authorization server; the method further comprises sending (1410) to the authorization server a discovery request to identify NFs of the communication network that are subscribed to notifications provided by the notifier NF; and the first message is a discovery response received in response to the discovery request.

14. The method of any of claims 11-13, wherein the first message includes one or more of the following: an indication of whether the subscription is implicit or explicit; an identifier of the subscription; a first validity duration associated with the subscription; a notification type associated with the subscription; a callback uniform resource identifier, URI, at which the receiver NF can receive the notifications; a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated;one or more of the following associated with the receiver NF: NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

15. The method of claim 14, wherein the access token request includes an indication that the requested access token is for notifications and one or more of the following information that was included in the first message: the identifier of the subscription; the first validity duration associated with the subscription; the callback URI; the callback URI schema; the notification type associated with the subscription; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

16. The method of claim 15, wherein the first access token includes one or more of the following information that was included in the first message and the access token request: the identifier of the subscription; the callback URI; the callback URI schema; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

17. The method of any of claims 15-16, wherein: the first validity duration associated with the subscription is included in the first message and the access token request; and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity.

18. The method of any of claims 11-17, wherein the first message includes a second access token indicating that the receiver NF is authorized to subscribe to the notifications from the notifier NF.

19. The method of any of claims 11-18, wherein the access token request is sent to a uniform resource identifier, URI, that is specific to a notification authorization service of the authorization server.

20. The method of any of claims 11-19, wherein one or more of the following applies: the authorization server is a network repository function, NRF; the receiver NF is an access and mobility management function, AMF; and the notifier NF is a unified data management, UDM, function.

21. A method performed by an authorization server of a communication network, the method comprising: receiving (1550), from a notifier network function, NF, of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to a receiver NF of the communication network; authorizing (1560) the access token request based on an NF profile for the receiver NF that is registered in the authorization server; and based on authorizing (1560) the access token request, sending (1570) to the notifier NF a first access token in accordance with the access token request.

22. The method of claim 21, wherein the access token request includes one or more of the following information: an indication that the requested access token is for notifications; an identifier of the receiver NF’s subscription to notifications from the notifier NF; a first validity duration associated with the subscription; a callback uniform resource identifier, URI„ at which the receiver NF can receive notifications related to the subscription; a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated; a notification type associated with the subscription; andone or more of the following associated with the receiver NF: NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

23. The method of claim 22, wherein the first access token includes one or more of the following information that is included in the access token request: the identifier of the subscription; the callback URI; the callback URI schema; and one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances.

24. The method of any of claims 22-23, wherein: the first validity duration associated with the subscription is included in the access token request; and the first access token includes a second validity duration associated with the first access token, which is no longer than the first lifetime or duration of validity.

25. The method of any of claims 22-24, further comprising: receiving (1520) from the notifier NF a discovery request to identify NFs of the communication network that are subscribed to notifications provided by the notifier NF; identifying (1530) the receiver NF based on the registered NF profile and the discovery request; and sending (1540) to the notifier NF a discovery response that identifies the receiver NF and includes at least a portion of the information received in the access token request.

26. The method of any of claims 21-25, further comprising registering (1510) the NF profile of the receiver NF, wherein the registered NF profile includes one or more of the following: a callback uniform resource identifier, URI, schema, from which callback URIs for the receiver NF can be generated; and allowed NF information that identifies NF types, NF sets, and / or NF instances that are allowed to send notifications to the receiver NF.

27. The method of claim 26, where authorizing the access token request is based on detecting one or more of the following: a match or correspondence between the allowed NF information in the registered NF profile and one or more of the following associated with the notifier NF: NF type, NF set, and one or more NF instances; and a match or correspondence between the callback URI schema in the registered NF profile and a callback URI schema in the access token request28. The method of any of claims 21-27, wherein the access token request is received at a uniform resource identifier, URI, that is specific to a notification authorization service of the authorization server.

29. The method of any of claims 21-28, wherein one or more of the following applies: the authorization server is a network repository function, NRF; the receiver NF is an access and mobility management function, AMF;, and the notifier NF is a unified data management, UDM, function.

30. A method performed by a subscriber network function, NF, arranged to subscribe to notifications from a notifier NF of a communication network on behalf of a receiver NF of the communication network, the method comprising: receiving (1610), from the receiver NF, a service request indicating that the subscriber NF should subscribe to notifications from the notifier NF on behalf of the receiver NF; and sending (1620), to the notifier NF, a subscription request in accordance with the service request.

31. The method of claim 30, wherein the service request includes one or more of the following information: an identifier of the receiver NF’s subscription to notifications from the notifier NF; a first validity duration associated with the subscription; a callback uniform resource identifier, URI,, at which the receiver NF can receive notifications related to the subscription; a callback URI schema, from which callback URIs for notifications to the receiver NF can be generated; a notification type to which the receiver NF wants to subscribe;one or more of the following associated with the receiver NF : NF type, binding indication, NF set, NF service set, one or more NF instances, and one or more NF service instances; and one or more of the following associated with the notifier NF : NF type, NF set, and one or more NF instances.

32. The method of claim 31, wherein the subscription request includes the information included in the service request and an indication of whether the subscription is implicit or explicit.

33. The method of any of claims 29-32, wherein one or more of the following applies: the subscriber NF is a first access and mobility management function, AMF; the notifier NF is a unified data management, UDM, function; and the receiver NF is a second AMF different than the first AMF.

34. Network equipment (1708, 1800, 1900) configured to implement a receiver network function, NF (840, 910, 1040, 1110, 1212, 1902) arranged to receive notifications from notifier NFs (830, 930, 1030, 1130, 1222, 1902) of a communication network (200, 1702), the network equipment comprising: communication interface circuitry (1806, 1904) configured to communicate with the notifier NFs and with an authorization server (210, 820, 920, 1020, 1120, 1902) of the communication network; and processing circuitry (1802, 1904) operably coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to: send, to a first NF (810, 830, 930, 1010, 1030, 1130, 1211, 1222, 1902) of the communication network, a first message related to a subscription for receiving notifications from a notifier NF of the communication network; and receive, from the notifier NF, a notification in accordance with the subscription, wherein the notification includes or is received in association with a first access token indicating that the notifier NF is authorized to send the notification.

35. The network equipment of claim 34, wherein the processing circuitry and the communication interface circuitry are further configured to perform operations corresponding to any of the methods of claims 2-10.

36. Network equipment (1708, 1800, 1900) configured to implement a receiver network function, NF (840, 910, 1040, 1110, 1212, 1902) arranged to receive notifications from notifier NFs (830, 930, 1030, 1130, 1222, 1902) of a communication network (200, 1702), the network equipment being further configured to: send, to a first NF (810, 830, 930, 1010, 1030, 1130, 1211, 1222, 1902) of the communication network, a first message related to a subscription for receiving notifications from a notifier NF of the communication network; and receive, from the notifier NF, a notification in accordance with the subscription, wherein the notification includes or is received in association with a first access token indicating that the notifier NF is authorized to send the notification.

37. The network equipment of claim 35, being further configured to perform operations corresponding to any of the methods of claims 2-10.

38. A non-transitory, computer-readable medium (1804, 1904) storing computer-executable instructions that, when executed by processing circuitry (1802, 1904) of network equipment (1708, 1800, 1900) configured to implement a receiver network function, NF (840, 910, 1040, 1110, 1212, 1902) arranged to receive notifications from notifier NFs (830, 930, 1030, 1130, 1222, 1902) of a communication network (200, 1702), configure the network equipment to perform operations corresponding to any of the methods of claims 1-10.

39. A computer program product (1804a, 1904a) comprising computer-executable instructions that, when executed by processing circuitry (1802, 1904) of network equipment (1708, 1800, 1900) configured to implement a receiver network function, NF (840, 910, 1040, 1110, 1212, 1902) arranged to receive notifications from notifier NFs (830, 930, 1030, 1130, 1222, 1902) of a communication network (200, 1702), configure the network equipment to perform operations corresponding to any of the methods of claims 1-10.

40. Network equipment (1708, 1800, 1900) configured to implement a notifier network function, NF (830, 930, 1030, 1130, 1222, 1902) arranged to send notifications to receiver NFs(840, 910, 1040, 1110, 1212, 1902) of a communication network (200, 1702), the network equipment comprising: communication interface circuitry (1806, 1904) configured to communicate with the receiver NFs and with an authorization server (210, 820, 920, 1020, 1120, 1902) of the communication network; and processing circuitry (1802, 1904) operably coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to: receive, from a first NF (810, 910, 1040, 1120, 1211, 1902) of the communication network, a first message related to a subscription for a receiver NF to receive notifications from the notifier NF; send, to an authorization server (210, 820, 920, 1020, 1120, 1902) of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to the receiver NF; receive from the authorization server a first access token in accordance with the access token request; and send, to the receiver NF, a notification in accordance with the subscription request, wherein the notification includes or is sent in association with the first access token.

41. The network equipment of claim 40, wherein the processing circuitry and the communication interface circuitry are further configured to perform operations corresponding to any of the methods of claims 12-20.

42. Network equipment (1708, 1800, 1900) configured to implement a notifier network function, NF (830, 930, 1030, 1130, 1222, 1902) arranged to send notifications to receiver NFs (840, 910, 1040, 1110, 1212, 1902) of a communication network (200, 1702), the network equipment being further configured to: receive, from a first NF (810, 910, 1040, 1120, 1211, 1902) of the communication network, a first message related to a subscription for a receiver NF to receive notifications from the notifier NF; send, to an authorization server (210, 820, 920, 1020, 1120, 1902) of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to the receiver NF;receive from the authorization server a first access token in accordance with the access token request; and send, to the receiver NF, a notification in accordance with the subscription request, wherein the notification includes or is sent in association with the first access token.

43. The network equipment of claim 42, being further configured to perform operations corresponding to any of the methods of 12-20.

44. A non-transitory, computer-readable medium (1804, 1904) storing computer-executable instructions that, when executed by processing circuitry (1802, 1904) of network equipment (1708, 1800, 1900) configured to implement a notifier network function, NF (830, 930, 1030, 1130, 1222, 1902) arranged to send notifications to receiver NFs (840, 910, 1040, 1110, 1212, 1902) of a communication network (200, 1702), configure the network equipment to perform operations corresponding to any of the methods of claims 11-20.

45. A computer program product (1804a, 1904a) comprising computer-executable instructions that, when executed by processing circuitry (1802, 1904) of network equipment (1708, 1800, 1900) configured to implement a notifier network function, NF (830, 930, 1030, 1130, 1222, 1902) arranged to send notifications to receiver NFs (840, 910, 1040, 1110, 1212, 1902) of a communication network (200, 1702), configure the network equipment to perform operations corresponding to any of the methods of claims 11-20.

46. Network equipment (1708, 1800, 1900) configured to implement an authorization server (210, 820, 920, 1020, 1120, 1902) of a communication network (200, 1702), the network equipment comprising: communication interface circuitry (1806, 1904) configured to communicate with receiver network functions, NFs (840, 910, 1040, 1110, 1212, 1902) and notifier NFs (830, 930, 1030, 1130, 1222, 1902) of the communication network; and processing circuitry (1802, 1904) operably coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to: receive, from a notifier NF of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to a receiver NF of the communication network;authorize the access token request based on an NF profile for the receiver NF that is registered in the authorization server; and based on authorizing the access token request, send to the notifier NF a first access token in accordance with the access token request.

47. The network equipment of claim 46, wherein the processing circuitry and the communication interface circuitry are further configured to perform operations corresponding to the method of any of claims 22-29.

48. Network equipment (1708, 1800, 1900) configured to implement an authorization server (210, 820, 920, 1020, 1120, 1902) of a communication network (200, 1702), the network equipment being further configured to: receive, from a notifier network function, NF (830, 930, 1030, 1130, 1222, 1902) of the communication network, a request for an access token indicating that the notifier NF is authorized to send notifications to a receiver NF (840, 910, 1040, 1110, 1212, 1902) of the communication network; authorize the access token request based on an NF profile for the receiver NF that is registered in the authorization server; and based on authorizing the access token request, send to the notifier NF a first access token in accordance with the access token request.

49. The network equipment of claim 48, being further configured to perform operations corresponding to the method of any of claims 22-29.

50. A non-transitory, computer-readable medium (1804, 1904) storing computer-executable instructions that, when executed by processing circuitry (1802, 1904) of network equipment (1708, 1800, 1900) configured to implement an authorization server (210, 820, 920, 1020, 1120, 1902) of a communication network (200, 1702), configure the network equipment to perform operations corresponding to any of the methods of claims 21-29.

51. A computer program product (1804a, 1904a) comprising computer-executable instructions that, when executed by processing circuitry (1802, 1904) of network equipment (1708, 1800, 1900) configured to implement an authorization server (210, 820, 920, 1020, 1120, 1902) of a communication network (200, 1702), configure the network equipment to perform operations corresponding to any of the methods of claims 21-29.

52. Network equipment (1708, 1800, 1900) configured to implement a subscriber network function, NF (810, 910, 1010, 1211, 1902) arranged to subscribe to notifications from a notifier NF (830, 930, 1030, 1130, 1222, 1902) of a communication network (200, 1702) on behalf of a receiver NF (840, 910, 1040, 1110, 1212, 1902) of the communication network, the network equipment comprising: communication interface circuitry (1806, 1904) configured to communicate with the notifier NF and with the receiver NF; and processing circuitry (1802, 1904) operably coupled to the communication interface circuitry, whereby the processing circuitry and the communication interface circuitry are configured to: receive, from the receiver NF, a service request indicating that the subscriber NF should subscribe to notifications from the notifier NF on behalf of the receiver NF; and send, to the notifier NF, a subscription request in accordance with the service request.

53. The network equipment of claim 46, wherein the processing circuitry and the communication interface circuitry are further configured to perform operations corresponding to any of the methods of claims 31-33.

54. Network equipment (1708, 1800, 1900) configured to implement a subscriber network function, NF (810, 910, 1010, 1211, 1902) arranged to subscribe to notifications from a notifier NF (830, 930, 1030, 1130, 1222, 1902) of a communication network (200, 1702) on behalf of a receiver NF (840, 910, 1040, 1110, 1212, 1902) of the communication network, the network equipment being further configured to: receive, from the receiver NF, a service request indicating that the subscriber NF should subscribe to notifications from the notifier NF on behalf of the receiver NF; and send, to the notifier NF, a subscription request in accordance with the service request.

55. The network equipment of claim 48, being further configured to perform operations corresponding to any of the methods of claims 31-33.

56. A non-transitory, computer-readable medium (1804, 1904) storing computer-executable instructions that, when executed by processing circuitry (1802, 1904) of network equipment(1708, 1800, 1900) configured to implement a subscriber network function, NF (810, 910, 1010, 1211, 1902) of a communication network (200, 1702), configure the network equipment to perform operations corresponding to any of the methods of claims 30-33.

57. A computer program product (1804a, 1904a) comprising computer-executable instructions that, when executed by processing circuitry (1802, 1904) of network equipment (1708, 1800, 1900) configured to implement a subscriber network function, NF (810, 910, 1010, 1211, 1902) of a communication network (200, 1702), configure the network equipment to perform operations corresponding to any of the methods of claims 30-33.

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