UE policy based on UE activity

Abstract

A policy control function PCF monitors whether a condition of a first trigger for a UE is met; and retrieves local activity information on an activity of the UE if the condition of the first trigger i

Description

Field of the invention The present disclosure relates to policy control. Abbreviations 3GPP 3rd Generation Partnership Project (RTM) 5G / 6G / 7G 5th / gth / ?th Generation 5GC 5G Core network AF Application Function AM Access and Mobility Management AMF Access and Mobility Management Function API Application Programming Interface DCAMP Dynamically Changing Access and Mobility management Policies DN Data Network DNN Data Network Name DNS Domain Name System EC Edge Computing FQDN Fully Qualified Domain Name H-PCF Home Policy Control Function HPLMN Home PLMN ID Identifier LBO Local Breakout MDAF Management Data Analytics Function NWDAF Network Data Analytics Function PCF Policy Control Function PCRT Policy Control Request Trigger PDU Protocol Data Unit PLMN Public Land Mobile Network PRA Presence Reporting Area RAT Radio Access Technology S-NSSAI Single Network Slice Selection Assistance Information SUPI Subscription Permanent Identifier TR Technical Report TS Technical Specification UDR Unified Data Repository UE User Equipment URSP UE Route Selection Policy V2X Vehicle-to-anything V-PCF Visited Policy Control Function Background In 5G, the UE can be provisioned with URSP (UE Route Selection Policy) rules, which steer the UE to select a PDU Session with certain parameters (e.g. with the proper target DNN and S-NSSAI) for certain traffic, potentially depending on the UE location. For example, a URSP rule can instruct the UE to use a PDU Session with dnn1 ,s-nssai1 whenever the UE is sending traffic towards app1.com ("domain descriptor" of the URSP rule) and the UE is located in a certain area ("spatial validity" of the URSP rule). URSP rules are specified in 3GPP TS 23.503, clause 6.6.2. As specified in 3GPP 23.502, clauses 4.16.11 and 4.16.12, the URSP rules are determined by the Policy Control Function (PCF) of the Home Public Land Mobile Network (HPLMN), denoted as H-PCF (before / during an initial provisioning or an Update of the UE policies, i.e. actions 4 and / or 6 of Figure 1). The determination may be based on: • information provided in the AMF UEPolicyControl_Create / Update request (e.g. UE location, PLMN ID, access type, RAT type etc.) • local PCF configuration / logic (including related policy data retrieved from UDR) • potential external requests for URSP guidance that the H-PCF has previously received from an Application Function (AF) (as per the procedure of 3GPP TS 23.502, clause 4.15.6.10). The actions according to Fig. 1 related to UE policy association establishment are substantially as follows: 1. The AMF establishes UE Policy Association with the (V-)PCF when a UE Policy Container is received from the UE. If a UE Policy Container is not received from the UE, the AMF may establish UE Policy Association with the (V-)PCF based on AMF local configuration. 2. The AMF sends a Npcf_UEPolicyControl Create Request to (V-)PCF, The request comprises (inter alia) an ID of the UE (SUPI). In roaming scenario, the V-PCF contacts the H-PCF. In roaming case, steps 3 and 4 are executed, otherwise step 5 follows. 3. The V-PCF forwards the information received from AMF in action 2 to the H-PCF. 4. The H-PCF sends a Npcf_UEPolicyControl Create Response to the V-PCF. The H-PCF may provide the Policy Control Request Trigger parameters in the Npcf_UEPolicyControl Create Response. 5. The (V-) PCF sends a Npcf_UEPolicyControl Create Response to the AMF. The (V-)PCF relays the Policy Control Request Trigger parameters in the Npcf_UEPolicyControl Create Response. 6. The (H-)PCF may get policy subscription related information from the UDR and makes a policy decision. In the non-roaming case, the PCF may subscribe to Analytics from NWDAF as defined in clause 6.1.1.3 of 3GPP TS 23.503. 7. The V-PCF sends a response to H-PCF using Npcf_UEPolicyControl UpdateNotify Response. 8. The (V-)PCF triggers UE Configuration Update Procedure to send the UE policy container including UE policy information to the UE. 9. If the V-PCF received notification of the reception of the UE Policy container then the V-PCF forwards the notification response of the UE to the H-PCF using Npcf_UEPolicyControl_Update Request. 10. The H-PCF sends a response to the V-PCF. Action 6 (and action 7) may be omitted. Then the (H-)PCF creates the UE policy container including UE polices in action 2 (in the case of non-roaming) or action 3 (in the case of roaming). This means that the potential interactions with UDR as in action 6 will have to be executed in action 2 (non-roaming) or action 3 (roaming). This procedure concerns both roaming and non-roaming scenarios. In the non-roaming case the V-PCF is not involved and the role of the H-PCF is performed by the PCF. For the roaming scenarios, the V-PCF interacts with the AMF and the H-PCF interacts with the V-PCF. The actions according to Fig. 2 related to UE policy association modification are substantially as follows: 1. When a Policy Control Request Trigger condition is met, the AMF updates UE Policy Control Association and provides information on the conditions that have changed to the PCF. The AMF sends a Npcf_UEPolicyControl Update Request to (V-)PCF with the following information: UE Policy Association ID associated with the UE ID (SUPI) and the Policy Control Request Trigger met. In roaming scenario, the V-PCF contacts the H-PCF. In the roaming case, actions 2 and 3 are executed, otherwise action 4 follows. 2. The V-PCF forwards the information received from AMF in action 1 to the (H-)PCF. 3. The H-PCF replies to the V-PCF. In the non-roaming case, the PCF may subscribe to Analytics from NWDAF. 4. The (V-) PCF sends a Npcf_UEPolicyControl Update Response to the AMF. 5. The (H-)PCF may create the UE policy container including UE policy information. In the case of roaming the H-PCF may include the UE policy container in the Npcf_UEPolicyControl UpdateNotify Request. 6. The (V-)PCF sends a response to H-PCF using Npcf_UEPolicyControl UpdateNotify Response. Actions 7, 8 and 9 are the same as actions 8, 9 and 10 of procedure UE Policy Association Establishment in Fig. 1. This procedure concerns both roaming and non-roaming scenarios. In the non-roaming case the V-PCF is not involved. In the roaming case, the AMF interacts with the V-PCF and the H-PCF interacts with the V-PCF. The (V-)PCF can send updated UE Policies (including URSP) any time to the AMF using the Npcf_UEPolicyControl_UpdateNotify service operation, i.e. independently of any Npcf_UEPolicyControl_Create / Update request from the AMF. Information related to Access and Mobility of a UE can be sent from a VPLMN (Visited PLMN) to the HPLMN by using the interface between the V-PCF and the H-PCF (N24 interface). In the context of Dynamically Changing Access and Mobility management Policies (DCAMP), mechanisms enabling the interactions between a PCF for a UE (which can provide UE policies) and a PCF for a PDU Session (which can provide session-related information) have been specified. Summary It is an object of the present invention to improve the prior art. According to a first aspect of the invention, there is provided an apparatus comprising: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform: monitoring whether a condition of a first trigger for a terminal is met; retrieving local activity information on an activity of the terminal if the condition of the first trigger is met; determining, based on the local activity information, a policy for the terminal; providing the policy to the terminal. The policy may comprise a route selection policy for the terminal. The providing the policy to the terminal may be performed by providing the policy to an access management function managing the terminal for forwarding the policy from the access management function to the terminal. The providing the policy may be performed by providing the policy to a policy control function of a network visited by the terminal for providing the policy from the policy control function of the network visited by the terminal to the access management function, wherein the access management function belongs to the network visited by the terminal, for forwarding the policy from the access management function to the terminal. According to a second aspect of the invention, there is provided an apparatus comprising: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform: monitoring whether a condition of a first trigger for a terminal is met; retrieving local activity information on an activity of the terminal if the condition of the first trigger is met; determining, based on the local activity information, a second trigger for triggering the retrieving the local activity information; providing the second trigger to at least one of: an access management function managing the terminal or a policy control function of a network visited by the terminal. In the apparatus according any of the first and second aspects, at least one of the following sub-aspects may apply: • The monitoring whether the condition of the first trigger is met may be performed by monitoring whether a trigger information is received that the condition of the first trigger is met. • The monitoring whether the condition of the first trigger is met may be performed by monitoring whether the trigger information is received from the policy control function of the network visited by the terminal, and the trigger information may further comprise roaming activity information on an activity of the terminal. • the determining the policy for the terminal additionally may be based on the roaming activity information; wherein the roaming activity information may comprise at least one of the following: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, a change of a usage of an application by the terminal, or a request for a domain name system from the terminal related to edge computing. • the retrieving the local activity information may be performed by retrieving the local activity information from at least one of the following functions: a policy control function of a home network of the terminal or an analytics function of the home network of the terminal. • The local activity information may comprise at least one of the following: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, a change of a usage of an application by the terminal, or a request for a domain name system from the terminal related to edge computing. According to a third aspect of the invention, there is provided an apparatus comprising: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform: monitoring whether a condition of a first trigger for a terminal is met; retrieving roaming activity information on an activity of the terminal if the condition of the first trigger is met; providing the roaming activity information to a policy control function of a home network of the terminal; supervising whether, in response to the providing the roaming activity information, at least one of the following is received from the policy control function: a policy for the terminal or a second trigger for the terminal; if the policy is received: forwarding the policy to the terminal; if the second trigger is received: updating the first trigger by the second trigger. The policy may comprise a route selection policy for the terminal. The forwarding the policy to the terminal may be performed by forwarding the policy to an access management function managing the terminal for forwarding the policy from the access management function to the terminal. The monitoring whether the condition of the first trigger is met may be performed by monitoring whether a trigger information is received that the condition of the first trigger is met. The retrieving the roaming activity information may be performed by retrieving the roaming activity information from at least one of the following functions: a policy control function of a network visited by the terminal or an analytics function of the network visited by the terminal. The roaming activity information may comprise at least one of the following: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, a change of a usage of an application by the terminal, or a request for a domain name system from the terminal related to edge computing. According to a fourth aspect of the invention, there is provided an apparatus comprising: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform: monitoring whether a second policy control function receives from a first policy control function a request to subscribe to an event of a request for a domain name system by a terminal; subscribing the first policy control server to the event if the second policy control function receives the request; checking whether the event of the request for the domain name system by the terminal occurs; and providing a notification to the first policy control function if the event of the request for the domain name system by the terminal occurs. According to a fifth aspect of the invention, there is provided an apparatus comprising: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform: monitoring whether an analytics function receives from a policy control function a request to subscribe to at least one of the following events for a terminal: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, or a change of a usage of an application by the terminal; subscribing the policy control function to the at least one of the events if the analytics function receives the request; and sending a notification to the policy control function if the analytics function detects at least one of the events. According to a sixth aspect of the invention, there is provided a method comprising: monitoring whether a condition of a first trigger for a terminal is met; retrieving local activity information on an activity of the terminal if the condition of the first trigger is met; determining, based on the local activity information, a policy for the terminal; providing the policy to the terminal. The policy may comprise a route selection policy for the terminal. The providing the policy to the terminal may comprise providing the policy to an access management function managing the terminal for forwarding the policy from the access management function to the terminal. The providing the policy may comprise providing the policy to a policy control function of a network visited by the terminal for providing the policy from the policy control function of the network visited by the terminal to the access management function, wherein the access management function belongs to the network visited by the terminal, for forwarding the policy from the access management function to the terminal. According to a seventh aspect of the invention, there is provided a method comprising: monitoring whether a condition of a first trigger for a terminal is met; retrieving local activity information on an activity of the terminal if the condition of the first trigger is met; determining, based on the local activity information, a second trigger for triggering the retrieving the local activity information; providing the second trigger to at least one of: an access management function managing the terminal or a policy control function of a network visited by the terminal. In the method according any of the sixth and seventh aspects, at least one of the following sub-aspects may apply: • the monitoring whether the condition of the first trigger is met may comprise monitoring whether a trigger information is received that the condition of the first trigger is met. • the monitoring whether the condition of the first trigger is met may comprise monitoring whether the trigger information is received from the policy control function of the network visited by the terminal, and the trigger information may further comprise roaming activity information on an activity of the terminal. • the determining the policy for the terminal may be additionally based on the roaming activity information; wherein the roaming activity information may comprise at least one of the following: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, a change of a usage of an application by the terminal, or a request for a domain name system from the terminal related to edge computing. • the retrieving the local activity information may comprise retrieving the local activity information from at least one of the following functions: a policy control function of a home network of the terminal or an analytics function of the home network of the terminal. • the local activity information may comprise at least one of the following: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, a change of a usage of an application by the terminal, or a request for a domain name system from the terminal related to edge computing. According to an eighth aspect of the invention, there is provided a method comprising: monitoring whether a condition of a first trigger for a terminal is met; retrieving roaming activity information on an activity of the terminal if the condition of the first trigger is met; providing the roaming activity information to a policy control function of a home network of the terminal; supervising whether, in response to the providing the roaming activity information, at least one of the following is received from the policy control function: a policy for the terminal or a second trigger for the terminal; if the policy is received: forwarding the policy to the terminal; if the second trigger is received: updating the first trigger by the second trigger. The policy may comprise a route selection policy for the terminal. The forwarding the policy to the terminal may comprise forwarding the policy to an access management function managing the terminal for forwarding the policy from the access management function to the terminal. The monitoring whether the condition of the first trigger is met may comprise monitoring whether a trigger information is received that the condition of the first trigger is met. The retrieving the roaming activity information may comprise retrieving the roaming activity information from at least one of the following functions: a policy control function of a network visited by the terminal or an analytics function of the network visited by the terminal. The roaming activity information may comprise at least one of the following: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, a change of a usage of an application by the terminal, or a request for a domain name system from the terminal related to edge computing. According to a ninth aspect of the invention, there is provided a method comprising: monitoring whether a second policy control function receives from a first policy control function a request to subscribe to an event of a request for a domain name system by a terminal; subscribing the first policy control server to the event if the second policy control function receives the request; checking whether the event of the request for the domain name system by the terminal occurs; and providing a notification to the first policy control function if the event of the request for the domain name system by the terminal occurs. According to a tenth aspect of the invention, there is provided a method comprising: monitoring whether an analytics function receives from a policy control function a request to subscribe to at least one of the following events for a terminal: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, or a change of a usage of an application by the terminal; subscribing the policy control function to the at least one of the events if the analytics function receives the request; and sending a notification to the policy control function if the analytics function detects at least one of the events. Each of the methods of the sixth to tenth aspects may be a method of policy determining. According to an eleventh aspect of the invention, there is provided a computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method according to any of the sixth to tenth aspects. The computer program product may be embodied as a computer-readable medium or directly loadable into a computer. According to some embodiments of the invention, at least one of the following advantages may be achieved: • information on UE activity may be used to determine a policy for the UE; • information on UE activity may be used to determine a policy control request trigger for the UE; • both is possible in roaming case and in non-roaming case; • existing mechanisms are exploited. It is to be understood that any of the above modifications can be applied singly or in combination to the respective aspects to which they refer, unless they are explicitly stated as excluding alternatives. Brief description of the drawings Further details, features, objects, and advantages are apparent from the following detailed description of the preferred embodiments of the present invention which is to be taken in conjunction with the appended drawings, wherein: Fig. 1 shows a message sequence chart according to 3GPP TS 23.502 (Fig. 4.16.11-1); Fig. 2 shows a message sequence chart according to 3GPP TS 23.502 (Fig. 4.16.12.1.1-1); Fig. 3 shows a message sequence chart according to some example embodiments of the invention; Fig. 4 shows a message sequence chart according to some example embodiments of the invention; Fig. 5 shows an apparatus according to an example embodiment of the invention; Fig. 6 shows a method according to an example embodiment of the invention; Fig. 7 shows an apparatus according to an example embodiment of the invention; Fig. 8 shows a method according to an example embodiment of the invention; Fig. 9 shows an apparatus according to an example embodiment of the invention; Fig. 10 shows a method according to an example embodiment of the invention; Fig. 11 shows an apparatus according to an example embodiment of the invention; Fig. 12 shows a method according to an example embodiment of the invention; Fig. 13 shows an apparatus according to an example embodiment of the invention; Fig. 14 shows a method according to an example embodiment of the invention; and Fig. 15 shows an apparatus according to an example embodiment of the invention. Detailed description of certain embodiments Herein below, certain embodiments of the present invention are described in detail with reference to the accompanying drawings, wherein the features of the embodiments can be freely combined with each other unless otherwise described. However, it is to be expressly understood that the description of certain embodiments is given by way of example only, and that it is by no way intended to be understood as limiting the invention to the disclosed details. Moreover, it is to be understood that the apparatus is configured to perform the corresponding method, although in some cases only the apparatus or only the method are described. As per the URSP determination and provisioning procedure described with respect to Figs. 1 and 2, the HPLMN has no way of using dynamic information related to UE activity, especially when the UE is roaming. Such information may be related to the following: • (Current or Future) Usage of certain applications and services • (Current or future) Activity level (e.g. expected size and characteristics of traffic) • Future UE mobility This information may be relevant for the determination of the URSP because of cases such as the following: • The fact that a UE is using service A (e.g. a V2X service) is an indication that the UE will use further similar (e.g. V2X) services. • UE that is expected to make intensive usage of a service. • UE that is expected to visit locations where it could be possible to use local application servers for certain services. In all of the above scenarios, it might be a good idea to provision URSP rules enabling edge computing for the affected services. With only the information that is currently retrieved and used by the H-PCF for URSP determination, the achieved latency and throughput are expected to be sub-optimal in various scenarios. According to some example embodiments of the invention, the (H-)PCF is made aware of UE activity information and uses this information to determine and provision one or more URSP policies. Example embodiments may be applied to any of the roaming case and the non-roaming case. For this purpose, at least one of the UE Policy Association Establishment (and Modification) procedures shown in Figs. 1 and 2 may be modified in the following way: • Add interactions of the PCF for the UE with the PCF for a PDU Session and the NWDAF to collect UE activity information before determining and provisioning the URSP policy (applicable in both roaming and non-roaming). • For the LBO roaming case (where the H-PCF cannot access the PCF for a PDU Session and the NWDAF of the VPLMN), extend the Npcf_UEPolicyControl service with “roaming-only” Policy Control Request Triggers (PCRT) that are used to carry between the V-PCF and the H-PCF events about UE activity (with additional information that the V-PCF retrieves from the PCF for a PDU Session and the NWDAF of the VPLMN). • Determine URSP policies using UE activity information. In addition, one or more of UE location, local policies, URSP guidance (if available) may be used. Hereinafter, we describe an example embodiment of the invention at greater detail, based on Figs. 3 and 4. Fig. 3 corresponds to Fig. 2. Thus, the explanations to Fig. 2 apply to Fig. 3 correspondingly, if not otherwise stated. This example embodiment describes, in Fig. 3, collection, circulation in 5GC, and consideration of UE activity information. Fig. 4 shows the sub-procedure performed by the PCF for a UE to collect UE activity information from at least one of the following functions: the PCF for a PDU Session or the NWDAF. The actions in Fig. 3 are as follows: 1. AMF determines to update UE policy association because a trigger condition is met. 2. As in action 1 of Fig. 2, AMF sends a Npcf_UEPolicyControl Update Request to (V-)PCF with the following information: UE Policy Association ID associated with the UE ID (SUPI) and the Policy Control Request Trigger met. In roaming scenario, the V-PCF contacts the H-PCF. In the roaming case, actions 3 and 4 are executed, otherwise action 5 follows. 2a. The V-PCF collects information about the UE activity from at least one of: one or more PCFs for PDU Session (which manage sessions of this UE) or from the NWDAF. An example is shown in Fig. 4. This collection can be triggered by action 2 (which is optional for UE Policy I URSP provisioning or updating) or by the V-PCF itself. 3. If the H-PCF has set during UE Policy Association Establishment the respective one or more PCRTs, the V-PCF passes, via the N24 interface, the collected UE activity data to the H-PCF. The UE activity data may be in the form of PCRT information. The message from V-PCF to H-PCF may indicate that the PCRT information applies only in roaming, i.e. only when the UEPolicyControl service is used between the V-PCF and the H-PCF (including also the UE Policy Association modification request information received in action 2, if applicable). Table 1 shows examples of these PCRTs and the information that is provided with them. For example, if the V-PCF received predictions about future locations of the UE from the NWDAF (of the VPLMN) in action 2, then it may set the "Predicted Location change" trigger in the message of this action 3, accompanying this trigger data that was received from the NWDAF. 3a. Same as action 2a but performed by the H-PCF (for the UE), interacting with one or more PCFs for PDU Session and / or NWDAF of the HPLMN this time. The H-PCF (for the UE) uses the information received in action 3 (if any) and the information gathered in action 3a (or 6a) to determine one or both of the PCRT (“second trigger”) and the URSP for the UE. In some cases, the provisioning of updated URSP may trigger a re-evaluation of the PDU Session selection at the UE. Thus, the provisioned URSP may target also ongoing traffic / session, e.g. moving certain traffic to the "right" slice. This description applies correspondingly to action 6a. 4. The H-PCF indicates to the V-PCF which PCRTs (“second trigger”) shall be set, i.e. indicates to the V-PCF which kinds of information (among the possible information listed in Table A) shall be provided to the H-PCF (in the next occurrence of action 3). Actions 5 to 8 correspond to actions 4 to 7 of Fig. 2. Therein, the H-PCF may (again) retrieve UE activity information (action 6a) in the same way as described for action 3a. This is particularly useful if action 3a was omitted (e.g. in the non-roaming case). According to some example embodiments of the invention, H-PCF performs at least one of actions 3a and 6a. If H-PCF performs action 3a, it may use the retrieved information for determining the URSP to be provided to V-PCF in action 6, without retrieving such information again in action 6a. In the non-roaming case, the V-PCF is replaced by the PCF, the interactions between the V-PCF and the H-PCF do not take place, action 2a does not take place, and actions 3a and 6a (or one of them) take place at the PCF. The procedure is technically applicable in both LBO and Home-routed roaming. According to some example embodiments, the method of Fig. 1 may be adapted in a corresponding way as Fig. 3 is an adaptation of Fig. 2. In particular, according to some example embodiments of the invention, H-PCF may determine trigger parameters (PCRT, “second trigger”) based on activity information of VPLMN or HPLMN and provide them to V-PCF in action 4 of (adapted) Fig. 1. Some example embodiments of the invention may adopt one or both of the methods of an adapted Fig. 1 and Fig. 3. Fig. 4 shows a message sequence chart according to some example embodiments of the invention. It shows a method performed in one, two, or all of action 2a, action 3a, or action 6a of Fig. 3. Fig. 4 shows an example where the PCF for UE retrieves activity information from both a PCF for a PDU session and NWDAF. However, according to some example embodiments of the invention, PCF for UE may retrieve activity information from more than one PCFs for PDU session. Furthermore, according to some example embodiments of the invention, PCF for UE may retrieve activity information from one or more PCFs for PDU session only, or from NWDAF only. In some example embodiments, the activity information may be retrieved from MDAF instead of or in addition to NWDAF. The actions shown in the example embodiment of Fig. 4 are as follows: 1. The PCF for a UE discovers PCF for a PDU Session that handle sessions of the UE and subscribes to events about these UEs. For this purpose, for example, existing procedures currently used only in the context of AM Policy provisioning may be 5 used. In order to retrieve information about UE activity, these events may include (at least) the subscription to "start or stop of applications" and the subscription to a new event type related to "DNS requests towards a specific targets / FQDNs" (because such requests may indicate the future usage of specific services). 10 2. The PCF for a UE subscribes to the NWDAF about analytics related to UE activity. This may include "UE mobility predictions" (already specified in the NWDAF API) or an analytics that is related to "UE activity level (per service) predictions" (e.g. the UE is expected to send traffic load X towards service Y at time Z). 15 Table 1 lists PCRTs according to some example embodiments of the invention (in bold) together with some conventional PCRTs (not in bold). POLICY CONTROL REQUEST TRIGGER DESCRIPTION ADDITIONAL INFORMATION PROVIDED UPON EVENT OCCURRENCE Location change (tracking area) The tracking area of the UE has changed. UE location Change of UE presence in Presence Reporting Area The UE is entering / leaving a PRA. PRAs PLMN change The UE has moved to another operator. PLMN id Connectivity state changes The connectivity state of UE is changed. Connectivity state Predicted Location change The predicted location of the UE has changed UE mobility analytics output Predicted UE activity level (per service) change The predicted UE activity per service has changed. UE activity level analytics output Application usage change The applications used by the UE have changed List of started and stopped applications EC-related DNS requests The application has performed DNS requests that indicate EC-related service usage DNS requests or list of used services Table 1: PCRTs according to some example embodiments of the invention Fig. 5 shows an apparatus according to an example embodiment of the invention. The apparatus may be a policy control function (such as a PCF, in particular a H-PCF) or an element thereof. Fig. 6 shows a method according to an example embodiment of the invention. The apparatus according to Fig. 5 may perform the method of Fig. 6 but is not limited to this method. The method of Fig. 6 may be performed by the apparatus of Fig. 5 but is not limited to being performed by this apparatus. The apparatus comprises means for monitoring 110, means for retrieving 120, means for determining 130, and means for providing 140. The means for monitoring 110, means for retrieving 120, means for determining 130, and means for providing 140 may be a monitoring means, retrieving means, determining means, and providing means, respectively. The means for monitoring 110, means for retrieving 120, means for determining 130, and means for providing 140 may be a monitor, retriever, determiner, and provider, respectively. The means for monitoring 110, means for retrieving 120, means for determining 130, and means for providing 140 may be a monitoring processor, retrieving processor, determining processor, and providing processor, respectively. The means for monitoring 110 monitors whether a condition of a first trigger for a terminal is met (S110). This condition may be an internal condition, or a corresponding information may be received from an access management function (e.g. from an AMF) or from another PCF (V-PCF). If the condition of the first trigger is met (S110 = yes), the means for retrieving 120 retrieves a local activity information for the terminal (S120). The local activity information comprises information on an activity of the terminal, in particular information accessible in the local network (home network or roaming network) where the terminal is present. Based on the local activity information of S120, the means for determining 130 determines a policy for the terminal (S130).The means for providing 140 provides the determined the policy to the terminal (S140). The providing may be directly to the terminal or indirectly (via AMF, or via V-PCF and AMF). Fig. 7 shows an apparatus according to an example embodiment of the invention. The apparatus may be a policy control function (such as a PCF, in particular a H-PCF) or an element thereof. Fig. 8 shows a method according to an example embodiment of the invention. The apparatus according to Fig. 7 may perform the method of Fig. 8 but is not limited to this method. The method of Fig. 8 may be performed by the apparatus of Fig. 7 but is not limited to being performed by this apparatus. The apparatus comprises means for monitoring 160, means for retrieving 170, means for determining 180, and means for providing 190. The means for monitoring 160, means for retrieving 170, means for determining 180, and means for providing 190 may be a monitoring means, retrieving means, determining means, and providing means, respectively. The means for monitoring 160, means for retrieving 170, means for determining 180, and means for providing 190 may be a monitor, retriever, determiner, and provider, respectively. The means for monitoring 160, means for retrieving 170, means for determining 180, and means for providing 190 may be a monitoring processor, retrieving processor, determining processor, and providing processor, respectively. The means for monitoring 160 monitors whether a condition of a first trigger for a terminal is met (S160). This condition may be an internal condition, or a corresponding information may be received from an access management function (e.g. from an AMF) or from another PCF (V-PCF). If the condition of the first trigger is met (S160 = yes), the means for retrieving 170 retrieves a local activity information for the terminal (S170). The local activity information comprises information on an activity of the terminal, in particular information accessible in the local network (home network or roaming network) where the terminal is present. Based on the local activity information of S170, the means for determining 180 determines a second trigger for triggering the retrieving the local activity information (S180). I.e., the second trigger may update the first trigger of S160 for the next time, when the method is executed. “Updating the first trigger” may mean “replacing the one or more conditions defined by the first trigger”, or “adding a further condition to the one or more conditions defined by the first trigger”, or “removing at least one of the one or more conditions defined by the first trigger”. The means for providing 190 provides the second trigger to at least one of: a policy control function of a network visited by the terminal or an access management function managing the terminal (e.g. via the PCF of the network visited by the terminal) (S190). Fig. 9 shows an apparatus according to an example embodiment of the invention. The apparatus may be a policy control function (such as a PCF, in particular a V-PCF) or an element thereof. Fig. 10 shows a method according to an example embodiment of the invention. The apparatus according to Fig. 9 may perform the method of Fig. 10 but is not limited to this method. The method of Fig. 10 may be performed by the apparatus of Fig. 9 but is not limited to being performed by this apparatus. The apparatus comprises means for monitoring 210, means for retrieving 220, means for providing 230, means for supervising 240, and at least one of: means for forwarding 250 or means for updating 251. The means for monitoring 210, means for retrieving 220, means for providing 230, means for supervising 240, means for forwarding 250, and means for updating 251 may be a monitoring means, retrieving means, providing means, supervising means, forwarding means, and updating means, respectively. The means for monitoring 210, means for retrieving 220, means for providing 230, means for supervising 240, means for forwarding 250, and means for updating 251 may be a monitor, retriever, provider, supervisor, forwarder, and updater, respectively. The means for monitoring 210, means for retrieving 220, means for providing 230, means for supervising 240, means for forwarding 250, and means for updating 251 may be a monitoring processor, retrieving processor, providing processor, supervising processor, forwarding processor, and updating processor, respectively. Fig. 9 shows an example embodiment comprising both the means for forwarding 250 and the means for updating 251. The means for monitoring 210 monitors whether a condition of a first trigger for a terminal is met (S210). This condition may be an internal condition, or a corresponding information may be received from an access management function (e.g. from an AMF). If the condition of the first trigger is met (S210 = yes), the means for retrieving 220 retrieves roaming activity information on an activity of the terminal (S220). The means for providing 230 provides the roaming activity information to a policy control function of a home network of the terminal (S230). The means for supervising 240 supervises whether, in response to the providing the roaming activity information in S230, at least one of the following is received from the policy control function of the home network of the terminal: a policy for the terminal or a second trigger for the terminal (S240). If it is determined in S240 that the policy for the terminal is received, the means for forwarding 250 forwards the received policy to the terminal (S250). If it is determined in S240 that the second trigger for the terminal is received, the means for updating 251 updates the first trigger for the terminal by the second trigger for the terminal (S251). If it is determined in S240 that both the policy and the second trigger are received, S250 and S251 may be performed in an arbitrary sequence. They may be performed fully or partly in parallel. Fig. 11 shows an apparatus according to an example embodiment of the invention. The apparatus may be a policy control function (such as a PCF, in particular a PCF for a PDU session) or an element thereof. Fig. 12 shows a method according to an example embodiment of the invention. The apparatus according to Fig. 11 may perform the method of Fig. 12 but is not limited to this method. The method of Fig. 12 may be performed by the apparatus of Fig. 11 but is not limited to being performed by this apparatus. The apparatus comprises means for monitoring 310, means for subscribing 320, means for checking 330, and means for providing 340. The means for monitoring 310, means for subscribing 320, means for checking 330, and means for providing 340 may be a monitoring means, subscribing means, checking means, and providing means, respectively. The means for monitoring 310, means for subscribing 320, means for checking 330, and means for providing 340 may be a monitor, subscriber, checker, and provider, respectively. The means for monitoring 310 means for subscribing 320, means for checking 330, and means for providing 340 may be a monitoring processor, subscribing processor, checking processor, and providing processor, respectively. The means for monitoring 310 monitors whether a second policy control server (such as a PCF for a PDU session) receives from a first policy control server (such as a PCF for a UE) a request to subscribe to an event (S310). The event comprises a request for a domain name server by a terminal. If the second policy control server receives the request (S310 = yes), the means for subscribing 320 subscribes the first policy control server to the event (S320). The means for checking 330 checks whether the event of the request for the domain name system by the terminal occurs (S330). If the event of the request for the domain name system by the terminal occurs (S330 = yes), the means for providing 340 provides a notification on the event to the first policy control function (S340). Fig. 13 shows an apparatus according to an example embodiment of the invention. The apparatus may be an analytics function (such as a NDAF or MDAF) or an element thereof. Fig. 14 shows a method according to an example embodiment of the invention. The apparatus according to Fig. 13 may perform the method of Fig. 14 but is not limited to this method. The method of Fig. 14 may be performed by the apparatus of Fig. 13 but is not limited to being performed by this apparatus. The apparatus comprises means for monitoring 410, means for subscribing 420, means for checking 430, and means for providing 440. The means for monitoring 410, means for subscribing 420, means for checking 430, and means for providing 440 may be a monitoring means, subscribing means, checking means, and providing means, respectively. The means for monitoring 410, means for subscribing 420, means for checking 430, and means for providing 440 may be a monitor, subscriber, checker, and provider, respectively. The means for monitoring 410 means for subscribing 420, means for checking 430, and means for providing 440 may be a monitoring processor, subscribing processor, checking processor, and providing processor, respectively. The means for monitoring 410 monitors whether an analytics function (such as NWDAF) receives from a policy control server (such as a PCF for a UE) a request to subscribe to an event for a terminal (S410). The event comprises at least one of the following: a predicted location change of the terminal, a predicted change of an activity level of the terminal on a service, or a change of a usage of an application by the terminal. If the analytics function receives the request (S410 = yes), the means for subscribing 420 subscribes the policy control function to the event (S420). The means for checking 430 checks whether at least one of the events occurs (S430). If the at least one of the events occurs (S330 = yes), the means for providing 340 provides a notification on the event to the first policy control function (S340). Fig. 15 shows an apparatus according to an example embodiment of the invention. The apparatus comprises at least one processor 810, at least one memory 820 storing instructions that, when executed by the at least one processor 810, cause the apparatus at least to perform the method according to at least one of the following figures and related description: Fig. 6 or Fig. 8 or Fig. 10 or Fig. 12 or Fig. 14. Some example embodiments are explained with respect to a 5G network. However, the invention is not limited to 5G networks. It may be used in other communication networks such as 4G, 6G, 7G networks, too if they provide corresponding functionality. I.e., it may be used even in non-3GPP mobile communication networks. A UE is an example of a terminal. It may be a mobile phone, a smartphone, a laptop, an loT device, a MTC device, etc. suitable to communicate with the respective network. One piece of information may be transmitted in one or plural messages from one entity to another entity. Each of these messages may comprise further (different) pieces of information. Names of network elements, network functions, protocolsand methods are based on current standards. In other versions or other technologies, the names of these network elements and / or network functions and / or protocols and / or methods may be different, as long as they provide a corresponding functionality. The same applies correspondingly to the terminal. If not otherwise stated or otherwise made clear from the context, the statement that two entities are different means that they perform different functions. It does not necessarily mean that they are based on different hardware. That is, each of the entities described in the present description may be based on a different hardware, or some or all of the entities may be based on the same hardware. It does not necessarily mean that they are based on different software. That is, each of the entities described in the present description may be based on different software, or some or all of the entities may be based on the same software. Each of the entities described in the present description may be deployed in the cloud. According to the above description, it should thus be apparent that example embodiments of the present invention provide, for example, a policy control server (such as a PCF) or a component thereof, an apparatus embodying the same, a method for controlling and / or operating the sameand computer program(s) controlling and / or operating the same as well as mediums carrying such computer program(s) and forming computer program product(s). According to the above description, it should thus be apparent that example embodiments of the present invention provide, for example, an analytics function (such as a NWDAF or a MDAF) or a component thereof, an apparatus embodying the same, a method for controlling and / or operating the sameand computer program(s) controlling and / or operating the same as well as mediums carrying such computer program(s) and forming computer program product(s). Implementations of any of the above described blocks, apparatuses, systems, techniques or methods include, as non-limiting examples, implementations as hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. Each of the entities described in the present description may be embodied in the cloud. It is to be understood that what is described above is what is presently considered the preferred example embodiments of the present invention. However, it should be noted that the description of the preferred example embodiments is given by way of example only and that various modifications may be made without departing from the scope of the invention as defined by the appended claims. The terms “first X” and “second X” include the options that “first X” is the same as “second X” and that “first X” is different from “second X”, unless otherwise specified. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

Claims

1. An apparatus, being a policy control function (H-PCF) of a home network of a terminal, comprising:one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform:monitoring whether a condition of a first trigger for the terminal is met;retrieving local activity information on an activity of the terminal if the condition of the first trigger is met, by retrieving the local activity information from at least one of: the policy control function (H-PCF) of the home network of the terminal or an analytics function of the home network of the terminal;determining, based on the local activity information, a policy for the terminal;providing the policy to the terminal,wherein the local activity information comprises at least one of the following: a predicted change of an activity level of the terminal on a service, or a request for a domain name system from the terminal related to edge computing.

2. The apparatus according to claim 1, wherein the policy comprises a route selection policy for the terminal.

3. The apparatus according to any of claims 1 to 2, wherein the instructions, when executed by the one or more processors, cause the apparatus to performthe providing the policy to the terminal by providing the policy to an access management function managing the terminal for forwarding the policy from the access management function to the terminal.

4. The apparatus according to claim 3, wherein the instructions, when executed by the one or more processors, cause the apparatus to performthe providing the policy by providing the policy to a policy control function of a network visited by the terminal for providing the policy from the policy control function of the network visited by the terminal to the access management function, wherein the access management function belongs to the network visited by the terminal, for forwarding the policy from the access management function to the terminal.

5. An apparatus, being a policy control function (H-PCF) of a home network of a terminal, comprising:one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform:monitoring whether a condition of a first trigger for the terminal is met;retrieving local activity information on an activity of the terminal if the condition of the first trigger is met, by retrieving the local activity information from at least one of: the policy control function (H-PCF) of the home network of the terminal or an analytics function of the home network of the terminal;determining, based on the local activity information, a second trigger for triggering the retrieving the local activity information;providing the second trigger to at least one of: an access management function managing the terminal or a policy control function (V-PCF) of a network visited by the terminal, wherein the local activity information comprises at least one of the following: a predicted change of an activity level of the terminal on a service, or a request for a domain name system from the terminal related to edge computing.

6. The apparatus according to any of claims 1 to 5, wherein the instructions, when executed by the one or more processors, cause the apparatus to performthe monitoring whether the condition of the first trigger is met by monitoring whether a trigger information is received that the condition of the first trigger is met.

7. The apparatus according to claim 6 dependent on at least one of claim 4 and claim 5, wherein the instructions, when executed by the one or more processors, cause the apparatus to performthe monitoring whether the condition of the first trigger is met by monitoring whether the trigger information is received from the policy control function of the network visited by the terminal, andthe trigger information further comprises roaming activity information on an activity of the terminal.

8. The apparatus according to claim 7, wherein the instructions, when executed by the one or more processors, cause the apparatus to performthe determining the policy for the terminal additionally based on the roaming activity information; whereinthe roaming activity information comprises at least one of the following: a predicted change of an activity level of the terminal on a service, a change of a usage of an application by the terminal, or a request for a domain name system from the terminal related to edge computing.

9. An apparatus, being a policy control function (V-PCF) of a network visited by a terminal, comprising:one or more processors and memory storing instructions that, when executed by the one or more processors, cause the apparatus to perform:monitoring whether a condition of a first trigger for the terminal is met;retrieving roaming activity information on an activity of the terminal if the condition of the first trigger is met, by retrieving the roaming activity information from at least one of: the policy control function (V-PCF) of the network visited by the terminal or an analytics function of the network visited by the terminal;providing the roaming activity information to a policy control function (H-PCF) of a home network of the terminal;supervising whether, in response to the providing the roaming activity information, at least one of the following is received from the policy control function (H-PCF) of the home network of the terminal: a policy for the terminal or a second trigger for the terminal;if the policy is received: forwarding the policy to the terminal;if the second trigger is received: updating the first trigger by the second trigger,wherein the roaming activity information comprises at least one of the following: a predicted change of an activity level of the terminal on a service, or a request for a domain name system from the terminal related to edge computing.

10. The apparatus according to claim 9, wherein the policy comprises a route selection policy for the terminal.

11. The apparatus according to any of claims 9 to 10, wherein the instructions, when executed by the one or more processors, cause the apparatus to performthe forwarding the policy to the terminal by forwarding the policy to an access management function managing the terminal for forwarding the policy from the access management function to the terminal.

12. The apparatus according to any of claims 9 to 11, wherein the instructions, when executed by the one or more processors, cause the apparatus to performthe monitoring whether the condition of the first trigger is met by monitoring whether a trigger information is received that the condition of the first trigger is met.

13. Method of a policy control function (H-PCF) of a home network of a terminal, the method comprising:monitoring whether a condition of a first trigger for the terminal is met;retrieving local activity information on an activity of the terminal if the condition of the first trigger is met, by retrieving the local activity information from at least one of: the policy control function (H-PCF) of the home network of the terminal or an analytics function of the home network of the terminal;determining, based on the local activity information, a policy for the terminal;providing the policy to the terminal,wherein the local activity information comprises at least one of the following: a predicted change of an activity level of the terminal on a service, or a request for a domain name system from the terminal related to edge computing.

14. Method of a policy control function (H-PCF) of a home network of a terminal, the method comprising:monitoring whether a condition of a first trigger for the terminal is met;retrieving local activity information on an activity of the terminal if the condition of the first trigger is met, by retrieving the local activity information from at least one of: the policy control function (H-PCF) of the home network of the terminal or an analytics function of the network visited by the terminal;determining, based on the local activity information, a second trigger for triggering the retrieving the local activity information;providing the second trigger to at least one of: an access management function managing the terminal or a policy control function (V-PCF) of a network visited by the terminal wherein the local activity information comprises at least one of the following: a predicted change of an activity level of the terminal on a service, or a request for a domain name system from the terminal related to edge computing.

15. Method of a policy control function (V-PCF) of a network visited by a terminal, the method comprising:monitoring whether a condition of a first trigger for the terminal is met;retrieving roaming activity information on an activity of the terminal if the condition of the first trigger is met, by retrieving the roaming activity information from at least one of: the policy control function (V-PCF) of the network visited by the terminal or an analytics function of the network visited by the terminal;providing the roaming activity information to a policy control function (H-PCF) of a home network of the terminal;supervising whether, in response to the providing the roaming activity information, at least one of the following is received from the policy control function (H-PCF) of the home network of the terminal: a policy for the terminal or a second trigger for the terminal;if the policy is received: forwarding the policy to the terminal;if the second trigger is received: updating the first trigger by the second trigger,wherein the roaming activity information comprises at least one of the following: a predicted change of an activity level of the terminal on a service, or a request for a domain name system from the terminal related to edge computing.

16. A computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method according to any of claims 13 to 15.

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