EP4070529A1

EP4070529A1 - User plane function load control

Info

Publication number: EP4070529A1
Application number: EP20807132.4A
Authority: EP
Inventors: Miguel Angel MUÑOZ DE LA TORRE ALONSO; Miguel Angel PUENTE PESTAÑA; Rodrigo Alvarez Dominguez
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2019-12-05
Filing date: 2020-11-09
Publication date: 2022-10-12
Also published as: WO2021111213A1

Abstract

A network node (500) of a wireless communication network (10) receives (205) load control information identifying a network slice and indicating a target load for the network slice. The network node (500) triggers (210) data collection at a user plane function (UPF) (35) that is in the identified network slice and that has a load above the target load. The network node (500) determines (215), based on a result of the data collection received from the UPF (35), a policy that achieves the target load at the UPF (35), and signals (220) a Policy Control Function (PCF) (50) in the identified network slice to control the load of the UPF (35) in accordance with the policy.

Description

USER PLANE FUNCTION LOAD CONTROL

RELATED APPLICATIONS

This application claims priority to EP Application 19383085.8, filed 5 December 2019, disclosure of which is incorporated in its entirety by reference herein.

TECHNICAL FIELD

The present disclosure generally relates to wireless communication networks, and more particularly relates to controlling user plane function (UPF) load in Third Generation Partnership Project (3GPP) networks.

BACKGROUND

The 3GPP is a telecommunication standards organization that produces specifications defining numerous technologies in support of wireless networks, such networks including (for example) Long Term Evolution (LTE) networks and Fifth Generation (5G) networks. A fundamental characteristic of a 5G core network is the separation of the control and user planes. The control plane is the portion of the network that handles signaling traffic, whereas the user plane is the portion of the network that handles network user traffic. Due to the ever- increasing amount of user traffic wireless communication networks are transporting (e.g., to stream high-definition video), the user plane is increasingly likely to be overloaded relative to the control plane.

SUMMARY

Embodiments of the present disclosure generally relate to methods of performing load control of the User Plane Function (UPF) in a wireless communication network. Particular embodiments take advantage of machine learning (ML) techniques that may be leveraged to autonomously perform UPF load control, e.g., on a per network slice basis. Among other things, such embodiments may reduce the amount of traffic handled by one or more UPFs while maintaining or even increasing the number of user sessions being serviced and/or mitigating negative impact to user experience.

One or more embodiments of the present disclosure includes a method implemented in a network node of a wireless communication network. The method comprises receiving load control information identifying a network slice and indicating a target load for the network slice. The method further comprises triggering data collection at a user plane function (UPF) that is in the identified network slice and that has a load above the target load. The method further comprises determining, based on a result of the data collection received from the UPF, a policy that achieves the target load at the UPF. The method further comprises signaling a Policy Control Function (PCF) in the identified network slice to control the load of the UPF in accordance with the policy.

In some embodiments, the method further comprises discovering the UPF that is in the identified network slice and that has the load above the target load in response to receiving the load control information.

In some embodiments, the method further comprises discovering the PCF in the identified network slice to control the load of the UPF in response to receiving the result of the data collection.

In some embodiments, the method further comprises sending a notification indicating that load control has completed in response to determining that the UPF is below the desired target load.

In some embodiments, the method further comprises registering with a Network Repository Function (NRF) that the network node supports user plane load control.

In some embodiments, the load control information further comprises an analytics identifier that indicates that user plane load control is desired.

In some embodiments, triggering data collection at the UPF comprises notifying the UPF of the target load, and the result of the data collection is received from the UPF responsive to the load of the UPF exceeding the target load.

In some embodiments, triggering data collection at the UPF comprises sending an event identifier corresponding to a type of data to be collected.

In some embodiments, the method further comprises receiving the result of the data collection from the UPF in an event notification message.

In some embodiments, determining the policy that achieves the target load at the UPF comprises determining a plurality of policy actions that achieves the target load at the UPF.

In some embodiments, the method further comprises triggering data collection at a further UPF that is in the identified network slice and that has a load above the target load, determining, based on a result of the data collection received from the further UPF, a further policy that achieves the target load at the further UPF, and signaling the PCF in the identified network slice to control the load of the further UPF in accordance with the further policy.

In some embodiments, determining the policy that achieves the target load at the UPF comprises determining a suggested Quality of Service action.

In some embodiments, determining the policy that achieves the target load at the UPF comprises determining an Adaptive Bit Rate policy.

In some embodiments, determining the policy that achieves the target load at the UPF comprises determining a bandwidth limitation.

In some embodiments, the method further comprises, responsive to signaling the PCF in the identified network slice to control the load of the UPF and after the load of the UPF has been controlled, receiving notification of a successful operation from the PCF. In some embodiments, receiving the load control information comprises receiving the load control information from an Operations and Maintenance (OAM) node. In some such embodiments, the method further comprises notifying the OAM node that the load has been controlled in accordance with the load control information.

In some embodiments, the network node comprises a Network Data Analytics Function (NWDAF).

One or more embodiments of the present disclosure includes a network node of a wireless communication network. The network node is configured to receive load control information identifying a network slice and indicating a target load for the network slice. The network node is further configured to trigger data collection at a user plane function (UPF) that is in the identified network slice and that has a load above the target load. The network node is further configured to determine, based on a result of the data collection received from the UPF, a policy that achieves the target load at the UPF. The network node is further configured to signal a Policy Control Function (PCF) in the identified network slice to control the load of the UPF in accordance with the policy.

In some embodiments, the network node is further configured to perform any of the methods described herein.

In some embodiments, the network node comprises interface circuitry configured to couple the network node to the wireless communication network. The network node further comprises processing circuitry communicatively coupled to the interface circuitry and whereby the network node is configured as described herein.

In some embodiments, the network node further comprises a memory communicatively coupled to the processing circuitry, and the memory contains instructions executable by the processing circuitry whereby the network node is configured as described herein.

Other embodiments include a computer program comprising instructions which, when executed on processing circuitry of a network node, cause the processing circuitry to carry out any of the methods described herein.

Other embodiments include a carrier containing such a computer program, the carrier being one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

Other embodiments include a non-transitory computer readable medium storing a computer program product for controlling a programmable network node in a wireless communication network. The computer program product comprises software instructions that, when run on the programmable network node, causes the programmable network node to perform any of the methods described herein. BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are illustrated by way of example and are not limited by the accompanying figures with like references indicating like elements.

Figure 1 is a schematic block diagram illustrating an example wireless communication network architecture according to one or more embodiments of the present disclosure.

Figure 2 is a flow diagram illustrating an example method according to one or more embodiments of the present disclosure.

Figures 3A through 3E are swimming lane diagrams illustrating a more detailed example method according to one or more embodiments of the present disclosure.

Figure 4 illustrates an example network node according to one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

Referring now to the drawings, example embodiments of the disclosure will be described below in the context of a 5G wireless communication network. Those skilled in the art will appreciate that the methods and apparatus herein described are not limited to use in 5G networks but may also be used in wireless communication networks operating according to other standards. Such embodiments may be particularly well suited for (but not limited to) derivatives of, and/or successors to, 5G networks, for example.

Figure 1 illustrates an example architecture of a wireless communication network 10 according to one or more embodiments of the present disclosure. The wireless communication network 10 comprises a radio access network (RAN) 20 and a core network 30 employing a service-based architecture. The RAN 20 comprises one or more base stations 25 providing radio access to UEs 100 operating within the wireless communication network 10. The base stations 25 are also referred to as gNodeBs (gNBs). The core network 30 provides a connection between the RAN 20 and other packet data networks, such as the Internet Protocol (IP) Multimedia Subsystem (IMS) or the Internet.

In an example embodiment, the core network 30 comprises a plurality of network functions (NFs), such as a User Plane Function (UPF) 35, an Access and Mobility Management Function (AMF) 40, a Session Management Function (SMF) 45, a Policy Control Function (PCF) 50, a Unified Data Management (UDM) function 55, an Authentication Server function (AUSF) 60, a Network Exposure Function (NEF) 70, a Network Repository Function (NRF) 75, a Network Slice Selection Function (NSSF) 80, and a Network Data Analytics Function (NWDAF) 65. These NFs comprise logical entities that reside in one or more core network nodes, which may be implemented by one or more processors, hardware, firmware, or a combination thereof. The functions may reside in a single core network node or may be distributed among two or more core network nodes. The various NFs (e.g., SMF 45, AMF 40, etc.) in the core network 30 communicate with one another over predefined interfaces. In the service-based architecture shown in Figure 1 , instead of predefined interfaces between the control plane functions, the wireless communication network 10 uses a services model in which the NFs query the NRF 75 or other NF discovery node to discover and communicate with each other.

The 5G core (5GC) network is designed to support network slicing. Network slicing allows the use of virtualized networks to separate networks designed for different purposes.

Each network slice provides customized features and connectivity specifically tailored for a specific purpose, and executes on a shared, distributed infrastructure that provides high availability and flexibility.

The Global System for Mobile Communications Association Network Group 116 (GSMA NG.116) describes a set of attributes that can be used by an operator to define a network slice type (NEST). These parameters include the maximum number of connections (e.g., concurrent Packet Data Unit (PDU) sessions) supported by the network slice and the maximum number of users (e.g., user equipment (UEs)) supported by the network slice. These attributes provide useful input to scale the network slice and provides enough physical resources to the network slice. There is a significant difference between a network slice designed to serve 10 users and a network slice designed to serve 1 ,000,000 users. Typically, either the maximum number of connections or the maximum number of terminals is defined by the NEST. The NEST can, in some cases define both the maximum number of connections and the maximum number of terminals supported by the network slice.

One aspect of the present disclosure comprises mechanisms for controlling the load of a UPF 35, particularly with respect to a given network slice in the network. In this regard, embodiments of the present disclosure include particular enhancements to the NWDAF 65, PCF 50, SMF 45, and/or UPF 35, as will be disclosed in further detail below.

The NWDAF 65, for example, represents an operator-managed network analytics logical function. The NWDAF 65 is part of the architecture specified in 3GPP TS 23.501 and uses the mechanisms and interfaces specified for the 5GC and Operations, Administration, and Maintenance (OAM). According to embodiments, the NWDAF 65 may interact with different entities in the network for different purposes. For example, the NWDAF 65 may trigger, request, and/or receive data collection based on event subscription, provided by AMF 40, SMF 45, PCF 50, UDM 55, an Application Function (AF) (e.g., directly or via NEF 70), and/or an OAM. The NWDAF 65 may additionally or alternatively retrieve information from data repositories (e.g. a Universal Data Repository (UDR) via the UDM 55 for subscriber-related information) and/or information about NFs (e.g. the NRF 75 for NF-related information and NSSF 80 for slice- related information). The NWDAF 65 may additionally or alternatively provide analytics to consumers on demand. The PCF 50 supports a unified policy framework to govern the behavior of the network.

In particular, the PCF 50 may provide Policy and Charging Control (PCC) rules to the SMF 45. The SMF 45 supports, e.g., session establishment, modification, and release, as well as policy related functionalities like termination of interfaces towards policy control functions, charging data collection, support of charging interfaces and/or control/coordination of charging data collection at the UPF 35. In particular embodiments, the SMF 45 receives PCC rules from the PCF 50 and configures the UPF 35 accordingly (e.g., through the N4 reference point using Packet Forwarding Control Protocol (PFCP).

According to embodiments, the SMF 45 controls the packet processing in the UPF 35 by establishing, modifying and/or deleting PFCP sessions and by provisioning (e.g., adding, modifying and/or deleting) Packet Detection Rules (PDRs), Forwarding Action Rules (FARs), Quality of Service (QoS) Enforcement Rules (QERs), and/or Usage Reporting Rules (URRs) per PFCP session. Note that a PFCP session may correspond to an individual PDU session or a standalone PFCP session not tied to any PDU session.

Each PDR contains Packet Detection Information (PDI) specifying the traffic filters and/or signatures against which incoming packets are matched. Each PDR is associated with rules that provide the set of instructions to apply to packets matching the PDI. These rules include one FAR that contains instructions related to the processing of the packets (e.g., forward, duplicate, drop, or buffer packets) with or without notifying the CP function about the arrival of a DL packet. The rules may also include zero, one, or more QERs that contain instructions related to the QoS enforcement of the traffic. The rules may also include zero, one, or more URRs that contain instructions related to traffic measurement and reporting.

The UPF 35 supports the handling of user plane traffic based on the rules received from the SMF 45. Among other things, the UPF 35 may perform packet inspection (e.g., through PDRs) and one or more enforcement actions. These enforcement actions may include, for example, traffic steering, QoS, and/or Charging/Reporting (e.g., through FARs, QERs, URRs).

To enable load control, entities within the network may need to be informed about the network slices for which such control is needed. According to embodiments of the present disclosure, one or more NFs may identify one or more network slices using Network Slice Selection Assistance Information (NSSAI), which is a collection of Single NSSAIs (S-NSSAIs) that may be used to identify network slices. Traditionally, up to eight (8) S-NSSAIs may be included in the NSSAI sent in signaling messages between a UE 100 and the network 10. In such embodiments, a single UE 100 may, at most, use eight network slices at a time. During normal operations, the UE 100 sends the S-NSSAI to the network 10 in a request (or other signaling message) to assist the network in selecting a particular network slice instance (NSI).

An S-NSSAI may comprise a Slice/Service type (SST), which refers to the expected features and services offered by the network slice. For example, currently defined service types include Enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communications (URLLC), Massive Internet of Things (MloT), vehicle-to-vehicle (V2V) communications and vehicle-to-everything (V2X) communications. The S-NSSAI may also optionally include a Slice Differentiator (SD) that further differentiates network slices of the same SST.

The S-NSSAI may be associated with a Public Land Mobile Network (PLMN) that is identified by a PLMN Identifer (PLMN ID). Generally, a UE 100 may provide the AMF 40 or SMF 45 with a S-NSSAI when the UE 100 is connected to an access network in the PLMN associated with the S-NSSAI. The S-NSSAI can have network-specific values, standard values, or some combination thereof.

PFCP load/overload control procedures may include a variety of approaches, which may (for example) be compatible with (or suitable for incorporation into) 3GPP TS 29.244. For example, a simple load control procedure may be used mainly for load balancing. According to one such procedure, the SMF 45 prioritizes selection of UPFs 35 with less load. Further, the overload control procedure may define mitigation actions (i.e., in case of overload) that are based on not allowing new sessions to be established (e.g., through message throttling, redirection and prioritization). Although embodiments that incorporate such an approach may be effective at controlling load, it should be noted that not allowing new sessions to be established may directly and negatively impact the user^'s experience, which would not be desirable.

In some embodiments, NFs (e.g. the UPF 35) may register NF load information in the NRF 75 so that when a consumer (e.g., SMF 45) triggers a discovery procedure, this load information can be used to achieve load balancing (e.g., when SMF 45 triggers a UPF 35 selection procedure). Such approaches may be compatible or suitable for incorporation into 3GPP TS 29.510, for example. These embodiments may also support subscription to NF load changes. However, the resulting notifications produced under such embodiments may be quite demanding on the network (e.g., in terms of network traffic).

Other embodiments may include different network functions (e.g. the UPF 35) sending load information to an OAM so that Performance Measurements (PM) or statistics may be taken. However, in general, traditional 5G networks do not define a procedure regarding what action(s) an OAM should perform in response to particular conditions (e.g., if a UPF load goes above a certain threshold).

In some embodiments, the NWDAF 65 may perform NF load analytics and provide those analytics (e.g., in the form of statistics or predictions or both) to other entities in the network. However, traditional 5G networks limit load analytics to the AMF 40, Non-3GPP Interworking Function (N3IWF, not shown), SMF 45, and PCF 50. That is, the UPF 35 is not included in the NF load analytics performed by a traditional NWDAF 65 (e.g., as discussed in 3GPP TS 29.288).

User plane NFs like the UPF 35 have a high risk of becoming overloaded, largely due to the exponential increase of user traffic (mainly due to video streaming applications). As compared with control plane NFs like the AMF 40, SMF 45, PCF 50, and NEF 70 (which only need to handle control plane signaling), user plane NFs are far more likely to suffer an overload.

Although a straightforward solution is to (over-)dimension the network (i.e., to simply deploy more UPFs), this has a high cost for the network operators, which are demanding from vendors more advanced techniques. Accordingly, embodiments of the present disclosure may include traffic optimization techniques (Transmission Control Protocol (TCP)/Quick User Datagram Protocol (UDP) Internet Connections (QUIC) optimization, Adaptive Bit Rate (ABR) shaping, etc) that reduce the amount of traffic handled by UPFs, while also maintaining support for at least the same number of user sessions and mitigating the negative impact of overloading on the user^'s experience. In so doing, embodiments are directed to implementing 5G networks as Smart Networks, and in particular, provide UPF load control procedures that may be fully automated and minimally impact existing network operability. Known UPF load control procedures as may be known in traditional 3GPP 5GC are still far from providing such solutions.

In view of the above, embodiments of the present disclosure address one or more of the problems described above. Particular embodiments propose to leverage the NWDAF 65 (e.g. using ML techniques) to automate control of the UPF load.

Figure 2 illustrates an example method 200 implemented by an NWDAF 65. The method 200 comprises receiving load control information identifying a network slice and indicating a target load for the network slice (block 205). The method 200 further comprises triggering data collection at a user plane function (UPF) 35 that is in the identified network slice and that has a load above the target load (block 210). The method 200 further comprises determining, based on a result of the data collection received from the UPF 35, a policy that achieves the target load at the UPF 35 (block 215). The method further comprises signaling a PCF 50 in the identified network slice to control the load of the UPF 35 in accordance with the policy (block 220).

In some embodiments, the method 200 further comprises discovering the UPF 35 that is in the identified network slice and that has the load above the target load in response to receiving the load control information (block 225). Additionally or alternatively, in accordance with particular embodiments, the method 200 may comprise discovering the PCF in the identified network slice to control the load of the UPF in response to receiving the result of the data collection from the UPF 35 (block 230).

To receive load control information identifying a network slice and indicating a target load for the network slice, the NWDAF 65 may (for example) receive a request from a consumer (e.g., an OAM) to activate NWDAF logic for a new Analytics-ID (e.g., Analytics-ID=UP_LOAD_CONTROL) and the request may comprise this load control information (e.g., a desired target load of below 70% and a network slice instance identifier corresponding to a particular Mobile Broadband (MBB) slice or MloT slice as parameters). In some embodiments, triggering the data collection may comprise indicating a particular event-id to the UPF in order to obtain certain information in response. For example, the NWDAF 65 may indicate an audio/video streaming event (e.g., using event-id=AUDIO_VIDEO_STREAMING). In such an embodiment, receiving the result of the data collection may comprise receiving a percentage of audio/video streaming traffic relative to the total traffic volume and/or one or more UE-IDs where audio/video streaming traffic has been detected. As another example, the NWDAF 65 may indicate a heavy users event (e.g., using event-id=HEAVY_USEFtS), and receiving the result of the data collection may comprise receiving a percentage of heavy user’s traffic relative to the total traffic volume and/or one or more UE-IDs corresponding to heavy users. As yet another example, the NWDAF 65 may indicate a UPF load event (e.g., using event-id=UPF_LOAD) to monitor the UPF load dynamically and receiving the result of the data collection may comprise receiving one or more UPF load reports from the UPF in response.

To enable the method 200, the NWDAF 65 may be pre-configured with one or more policies that may be applied to reduce UPF load, e.g. on a per slice type basis. For example, the NWDAF 65 may be preconfigured with a policy that may be effective to reduce UPF load for MBB types of slices. One or more of such policies may include an ABR shaping policy (e.g., to be applied to ABR streaming traffic such as Audio and/or Video streaming), Bandwidth (BW) limitation (e.g., to be applied to all traffic of only Heavy Users, which are defined as subscribers consuming more than a threshold amount of traffic, which is typically set quite high).

Accordingly, some embodiments include receiving one or more such policies and determining the policy that achieves the target load may comprise selecting one of the received policies.

According to embodiments, the NWDAF 65 may use the result of the data collection and apply ML techniques to determine the policy that will achieve the desired target load. Indeed, the NWDAF 65 may use information obtained from the above events, and determine suggested policy actions to achieve the desired target load on a per UPF instance basis.

For example, for Audio/Video streaming traffic, the NWDAF 65 determine the ABR shaping level/s to be applied. For Heavy users, the NWDAF 65 may determine the BW limitation level/s to be applied.

Moreover, in some embodiments, the NWDAF 65 may, for each UE-ID obtained, signal the PCF 50 to apply a policy that such that the PCF 50 creates/updates a corresponding PCC rule (i.e., corresponding to the above policies) and sends it to an SMF 45. The SMF 45 may then trigger, towards the UPF 35, a PFCP Session Modification procedure with the corresponding policies. The UPF may then detect traffic and apply a corresponding policy (e.g., ABR shaping for Audio/Video Streaming traffic and/or BW limitation for heavy users).

In some embodiments, the method 200 further comprises sending a notification indicating that load control has completed in response to determining that the UPF 35 is below the target load (block 235). For example, in response to determining that all the UPFs in the slice are below the desired target load, the NWDAF 65 may notify the consumer (e.g., OAM) that load control has been completed using Analytic-ID=UP_LOAD_CONTROL and Result=DONE.

In view of the example above, embodiments of the present disclosure may automate the control of user plane load on a per slice basis using an NWDAF 65 (e.g., by applying ML techniques). Figures 3A through 3E illustrate a more detailed example of automating control of user plane load for a MBB slice. In this regard, Figure 3 is a swimming lane diagram illustrating signaling between entities within a wireless communication network 10. Although the example of Figures 3A through 3E illustrates forty steps, particular embodiments may include additional, fewer, or different steps from those illustrated therein, consistent with the discussion above and/or variations as further described below.

According to the embodiment illustrated in Figures 3A through 3E, the NWDAF 65 has previously registered in the NRF 75 that it supports user plane load control, e.g., by signaling support for Analytic-ID=UP_LOAD_CONTROL. As used in this embodiment, Analytic- ID=UP_LOAD_CONTROL The NWDAF 65 is preconfigured with the suggested policies to be applied to reduce the UPF load on a per slice type basis. For example, for an MBB type of slice, the NWDAF 65 is preconfigured with an ABR shaping policy to be applied to ABR streaming traffic (e.g., to Audio and Video streaming) and/or a BW limitation policy to be applied to all the traffic of only Heavy Users (i.e., subscribers consuming more than a threshold amount of traffic). The NWDAF may additionally or alternatively be preconfigured with one or more other policies that may be applied to reduce the UPF load, e.g., a TCP Optimization policy to be applied to TCP traffic and/or a QUIC Optimization policy to be applied to QUIC traffic.

Moreover, according to the embodiment of Figures 3A through 3E, the UPF 35 has registered with the NRF that it supports the Event-IDs AUDIO_VIDEO_STREAMING,

HEAVY USERS, and UPFJ.OAD.

According to step 1 (and with reference to Figure 3A), a consumer (e.g. OAM) wants the user plane load for a certain slice (e.g., MBB1) to be below a certain threshold (e.g. 70%). Given that the NWDAF 65 supports user plane load control (and its corresponding Analytic-ID, e.g., UP_LOAD_CONTROL), the consumer (e.g. OAM) triggers a Nnwdaf_AnalyticsSubscription Subscribe message towards a previously discovered NWDAF 65 instance. The Subscribe message comprises the parameters Analytic-ID=UP_LOAD_CONTROL, Network-Slice- lnstance=MBB1 , and Load-Level-Threshold-Value=70%.

At Step 2, the NWDAF 65 accepts the request and answers the consumer (e.g. OAM) with a successful Nnwdaf_AnalyticsSubscription response message.

At Step 3, the NWDAF 65 triggers UPF discovery in order to identify UPF instances (i.e., preferably all) that pertain to the MBB1 slice and which are above the target load threshold of 70%. To trigger UPF discovery, at Step 4 the NWDAF 65 sends an Nnrf NFDiscovery message towards the NRF 75. The Nnrf NFDiscovery message comprises the parameters nfType=UPF, nfService=Nupf_EventExposure, and a upflnfo parameter that includes S-NSSAI=MBB1 and a list of Event- IDs (e.g., AUDIO_VIDEO_STREAMING, HEAVY USERS, UPF_LOAD). In some embodiments, the Nnrf NFDiscovery message further comprises a parameter that indicates the load of UPFs to discover (e.g., UPFs with load >=70%). Thus, according to one or more embodiments, the NWDAF 65 may perform discovery of UPFs that have load above a certain threshold.

At Step 5, the NRF 75 checks the registered NFProfiles and responds to the NWDAF 65 with a list of UPF instances matching the criteria in Step 4 above.

At Step 6, the NWDAF 65 triggers data collection from the UPF instances in the list received from the NRF 75. Note that although Figures 3A through 3E illustrate only a single UPF 35, other examples may include multiple UPFs 35. To trigger data collection, at Step 7 the NWDAF 65 triggers towards the relevant UPF 65 instance a Nupf_EventExposure Subscribe message. The Nupf_EventExposure Subscribe message comprises an event identifier (e.g., an Event- ID equal to UPFJ.OAD, AUDIO_VIDEO_STREAMING, or HEAVYJJSERS) and a network slice identifier (e.g., Network-Slice-lnstance=MBB1). The network slice identifier may be particularly useful according to embodiments in which a given UPF 35 instance serves different network slices concurrently.

In some embodiments, Event-ID=UPF_LOAD, and the Nupf_EventExposure Subscribe further comprises a load threshold (e.g. 70%). In response, the UPF 65 triggers a notification when the current load is equal or above the threshold.

In some embodiments, Event-ID=HEAVY_USERS, and the Nupf_EventExposure Subscribe further comprises a heavy user category. For example, heavy users may be categorized in accordance with the amount of traffic they generate.

At Step 8, the UPF 35 responds to the NWDAF 65 with an indication that the subscription request has bene accepted.

At Step 9, the UPF 35 activates the requested events. In one example, in response to Event-ID=UPF_LOAD being requested by the NWDAF 65, the UPF 35 monitors the load (e.g., CPU and Memory resources) and reports either periodically or when the current load is equal or above a certain threshold (e.g. 70%). In another example, in response to Event-ID= AUDIO_VIDEO_STREAMING being requested by the NWDAF 65, the UPF 35 detects audio/video streaming traffic (e.g. using Deep Packet Inspection (DPI) techniques) and calculates the percentage of audio/video streaming traffic with respect to the total amount of traffic. The UPF 35 also calculates for which UE-IDs there is presence of audio/video streaming traffic. In another example, in response to Event-ID= HEAVYJJSERS being requested by the NWDAF 65, the UPF 35 detects which UE-IDs are consuming more than a threshold amount of traffic (e.g. using DPI techniques, in accordance with the criteria for being classified as a heavy user category as discussed above, which may be locally configured in the UPF 35 for each heavy user category). In addition, the UPF 35 may calculate the percentage of heavy user^'s traffic (with respect to the total traffic volume) and identify the UE-IDs corresponding to heavy users.

At Step 10 (and with reference to Figure 3B), the UPF 35 triggers a Nupf_EventExposure Notify message towards the NWDAF 65 with the Event-ID=UPF_LOAD and Load-Information. The Load-Information comprises the UPF CPU and Memory usage for the identified slice. At Step 11 , the NWDAF 65 responds to the UPF 35 accordingly (e.g., to acknowledge the notification message indicating the UPF LOAD event identifier).

At Step 12, the UPF triggers a Nupf_EventExposure Notify message towards the NWDAF 65 with the Event-ID=AUDIO_VIDEO_STREAMING and Audio- Video-Streaming- Information. The Audio-Video-Streaming-Information comprises a Traffic-Percentage (percentage of audio/video streaming traffic with respect to the total amount of traffic) and a list of UE-IDs (referred to in this example as UE-IDs=List A, which is the list of UE-IDs with detected audio/video streaming traffic). At Step 13, the NWDAF 65 responds to the UPF 35 accordingly (e.g., to acknowledge the notification message indicating the AUDIO_VIDEO_STREAMING event identifier).

At Step 14, the UPF 35 triggers a Nupf_EventExposure Notify message towards the NWDAF 65 with the Event-ID=HEAVY_USERS and Heavy-Users-lnformation. The Heavy- Users-lnformation comprises a Traffic-Percentage (i.e., percentage of heavy user^'s traffic with respect to the total traffic volume) and a list of UE-IDs (referred to in this example as UE-IDs=List B, which is the list of UE-IDs corresponding to heavy users). At Step 15, the NWDAF 65 responds to the UPF 35 accordingly (e.g., to acknowledge the notification message indicating the HEAVYJJSERS event identifier).

At Step 16, the NWDAF 65 determines, on a per UPF instance basis, the suggested policy actions to achieve the desired target load. To determine the policy actions, the NWDAF 65 may use ML techniques and/or the information obtained from one or more of the above events. For example, for Audio/Video streaming traffic, the NWDAF 65 may determine the ABR shaping level (hereinafter referred to as an X value) to be applied. Additionally or alternatively, for Heavy users, the NWDAF 65 may determine the BW limitation level (hereinafter referred to as a Y value) to be applied. These X and Y values may be obtained by the NWDAF 65 by any appropriate means. For example, the X and/or Y value may be preconfigured in, or calculated by, the NWDAF 65.

At Step 17, the NWDAF 65 discovers the PCF 50 instance(s) in the slice. To discover the PCF 50 instances, the NWDAF 65 triggers a Nnrf NFDiscovery message towards the NRF 75. The Nnrf NFDiscovery message comprises an NF type parameter indicating an NF Type (e.g., nfType=PCF), an NF service parameter indicating an NF Service (e.g., nfService=Npcf_PolicyControl), and an identifier of the PCF 50 (e.g., pcflnfo (S-NSSAI=MBB1)).

At Step 18, the NRF 75 responds to the Nnrf NFDiscovery message sent by the NWDAF 65 with a list of PCF addresses. In this example, a single PCF 50 is included in the list (i.e., as policy controller for the MBB1 slice). However, other examples may include a plurality of PCF addresses in the list that correspond to respective PCF 50 instances.

At Step 19 (and with reference to Figure 3C), the NWDAF 65 indicates to the identified PCF(s) 50 one or more suggested policies. To indicate a policy to a PCF 50, at Step 20 the NWDAF 65 triggers towards the PCF 50 a Npcf_PolicyControl Request message. The Npcf_PolicyControl Request message comprises a first list of UE-IDs (e.g., List A discussed above) with a Suggested-QoS-Action (e.g., indicating an ABR-Shaping-Level=X, as discussed above), and/or a second list of UE-IDs (e.g., List B discussed above) with a Suggested-QoS- Action (e.g., indicating a BW-Limit=Y, as discussed above).

At Step 21 , the PCF 50 decides to execute the suggested policies. To execute the suggested policies, the PCF 50 updates the policies on a per UE-ID basis. For example, at Step 22, for each UE-ID in list A (i.e., for the UE-IDs in which Audio/Video Streaming has been detected), the PCF 50 requests ABR shaping for Audio/Video Streaming traffic. To request ABR shaping, at Step 23 the PCF 50 triggers, towards the SMF 45, a Nsmf PolicyControl Request message. The Nsmf PolicyControl Request message comprises a UE-ID (i.e., from List A), a PCC rule (e.g., create, update). The PCC rule comprises an App-ID=Audio- Video- Streaming, and a QoS including the Suggested-QoS-Action (e.g., ABR-Shaping-Level=X).

At Step 24, for each UE-ID in List A, the SMF 45 triggers a PFCP Session Modification. To trigger the PFCP Session Modification, at Step 25, the SMF 45 sends a PFCP Session Modification Request message towards the UPF 35. The PFCP Session Modification Request message comprises a UE-ID (i.e., from List A), a PDR (e.g., with PDI of type App-ID=Audio- Video-Streaming), and a QER (e.g., ABR-Shaping-Level=X).

At Step 26, the UPF 35 detects Audio/Video streaming traffic based on the PDR and applies ABR shaping to the target level (i.e., X, in this example) based on the above QER. At Step 27, the UPF 35 answers the SMF 45 with a PFCP Session Modification Response. At Step 28, the SMF 45 answers the PCF 50 with a Nsmf PolicyControl Response.

Additionally or alternatively, to execute the suggested policies, at Step 29 (with reference to Figure 3D), for each UE-ID in List B (i.e., UE-IDs corresponding to Heavy Users), the PCF 50 requests a BW limitation for all user traffic with respect to that UE-ID. To request the BW limitation, at Step 30, the PCF 50 triggers towards the SMF 45 a Nsmf PolicyControl Request message. The Nsmf PolicyControl Request message comprises a UE-ID (i.e., from List B), and a PCC rule (e.g., create, update). The PCC rule comprises an App-ID=Match all (i.e., to match all user traffic in the session) and a QoS comprising the Suggested-QoS-Action (e.g., BW- Limit=Y).

At Step 31 , for each UE-ID in List B, the SMF 45 triggers a PFCP Session Modification. To trigger the PFCP Session Modification, at Step 32, the SMF 45 sends a PFCP Session Modification Request message towards the UPF 35. The PFCP Session Modification Request message comprises a UE-ID (i.e., from List B), a PDR (e.g., with PDI of type App-ID=Match all), and a QER (e.g., indicating BW-Limit=Y). At Step 33, the UPF 35 applies the BW limitation (e.g., of Y kbps) to all user traffic of the identified heavy user. At Step 34, the UPF 35 answers the SMF 45 with a PFCP Session Modification Response. At Step 35, the SMF 45 answers the PCF 50 with a Nsmf PolicyControl Response.

At Steps 36, once the PCF 50 has executed the suggested policies towards all UE-IDs (in each of List A and/or List B as applicable), the PCF 50 indicates to the NWDAF 65, at Step 37, that the operation was successful (e.g., by signaling Result=DONE).

At Step 38 (and with reference to Figure 3E), the NWDAF 65 checks whether the UPF(s) 35 in the slice are below the target Load-Level-Threshold-Value (i.e., from Step 1). If so, at Step 39, the NWDAF 65 notifies the consumer (e.g. OAM) by triggering a Nnwdaf_AnalyticsSubscription Notify message including Analytic-ID=UP_LOAD_CONTROL and Result=DONE. At Step 40, the consumer (e.g. OAM) answers the NWDAF 65 with a Nnwdaf_AnalyticsSubscription Notify response message.

Figure 4 illustrates a network node 500 according to one or more embodiments that may be configured to function as an NWDAF 65, NRF 75, AMF 40, SMF 45, PCF 50, or UPF 35, for example. The network node 500 comprises interface circuitry 520 and processing circuitry 530 that is communicatively coupled to the interface circuitry 520. In some embodiments, the network node 500 further comprises memory 540. The interface circuitry 520 couples the network node 500 to a wireless communication network 10 and enables communication with other network nodes in a core network 30 of the wireless communication network 10. The processing circuitry 530 controls the overall operation of the network node 500. In some embodiments, to control the overall operation of the network node 500, the processing circuitry 530 executes one or more computer programs 550 stored in memory 540 to perform one or more of the methods as herein described. The processing circuitry 530 may comprise one or more microprocessors, hardware, firmware, or a combination thereof. Memory 540 may comprises volatile memory and/or non-volatile memory for storing computer program code and data needed by the processing circuitry 530 for operation. The memory 540 may comprise any tangible, non-transitory computer-readable storage medium for storing data including electronic, magnetic, optical, electromagnetic, or semiconductor data storage. In particular, the memory 540 may store a computer program 550 comprising executable instructions that configure the processing circuitry 530 to implement the method 200 according to, e.g., Figure 2, Figures 3A through 3E, or one or more of the methods described above. A computer program 550 in this regard may comprise one or more code modules corresponding to the means or units described above. In general, computer program instructions and configuration information are stored in a non-volatile memory, such as a ROM, erasable programmable read only memory (EPROM) or flash memory. Temporary data generated during operation may be stored in a volatile memory, such as a random access memory (RAM). In some embodiments, the computer program for configuring the processing circuitry 530 as herein described may be stored in a removable memory, such as a portable compact disc, portable digital video disc, or other removable media. The computer program 550 may also be embodied in a carrier such as an electronic signal, optical signal, radio signal, or computer readable storage medium.

Those skilled in the art will also appreciate that embodiments herein further include corresponding computer programs. A computer program comprises instructions that, when executed on at least one processor of an apparatus, cause the apparatus to carry out any of the respective processing described above. A computer program in this regard may comprise one or more code modules corresponding to the means or units described above.

Embodiments further include a carrier containing such a computer program. This carrier may comprise one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

In this regard, embodiments herein also include a computer program product stored on a non-transitory computer readable (storage or recording) medium and comprising instructions that, when executed by a processor of an apparatus, cause the apparatus to perform as described above.

Embodiments further include a computer program product comprising program code portions for performing the steps of any of the embodiments herein when the computer program product is executed by a computing device. This computer program product may be stored on a computer readable recording medium.

The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

Claims

CLAIMS What is claimed is:

1. A method (200), implemented in a network node (500) of a wireless communication network (10), the method comprising: receiving (205) load control information identifying a network slice and indicating a target load for the network slice; triggering (210) data collection at a user plane function (UPF) (35) that is in the identified network slice and that has a load above the target load; determining (215), based on a result of the data collection received from the UPF (35), a policy that achieves the target load at the UPF (35); signaling (220) a Policy Control Function (PCF) (50) in the identified network slice to control the load of the UPF (35) in accordance with the policy.

2. The method of claim 1 , further comprising discovering the UPF (35) that is in the identified network slice and that has the load above the target load in response to receiving the load control information.

3. The method of any one of the preceding claims, further comprising discovering the PCF (50) in the identified network slice to control the load of the UPF (35) in response to receiving the result of the data collection.

4. The method of any one of the preceding claims, further comprising sending a notification indicating that load control has completed in response to determining that the UPF (35) is below the desired target load.

5. The method of any one of the preceding claims, further comprising registering with a Network Repository Function (NRF) (75) that the network node (500) supports user plane load control.

6. The method of any one of the preceding claims, wherein the load control information further comprises an analytics identifier that indicates that user plane load control is desired.

7. The method of any one of the preceding claims, wherein triggering data collection at the UPF (35) comprises notifying the UPF (35) of the target load, and wherein the result of the data collection is received from the UPF responsive to the load of the UPF exceeding the target load.

8. The method of any one of the preceding claims, wherein triggering data collection at the UPF (35) comprises sending an event identifier corresponding to a type of data to be collected.

9. The method of any one of the preceding claims, further comprising receiving the result of the data collection from the UPF (35) in an event notification message.

10. The method of any one of the preceding claims, wherein determining the policy that achieves the target load at the UPF (35) comprises determining a plurality of policy actions that achieves the target load at the UPF (35).

11. The method of any one of the preceding claims, further comprising: triggering data collection at a further UPF (35) that is in the identified network slice and that has a load above the target load; determining, based on a result of the data collection received from the further UPF (35), a further policy that achieves the target load at the further UPF (35); and signaling the PCF (50) in the identified network slice to control the load of the further UPF (35) in accordance with the further policy.

12. The method of any one of the preceding claims, wherein determining the policy that achieves the target load at the UPF (35) comprises determining a suggested Quality of Service action.

13. The method of any one of the preceding claims, wherein determining the policy that achieves the target load at the UPF (35) comprises determining an Adaptive Bit Rate policy.

14. The method of any one of the preceding claims, wherein determining the policy that achieves the target load at the UPF (35) comprises determining a bandwidth limitation.

15. The method of any one of the preceding claims, further comprising responsive to signaling the PCF (50) in the identified network slice to control the load of the UPF (35) and after the load of the UPF has been controlled, receiving notification of a successful operation from the PCF (50).

16. The method of any one of the preceding claims, wherein receiving the load control information comprises receiving the load control information from an Operations and Maintenance (OAM) node.

17. The method of the preceding claim, further comprising notifying the OAM node that the load has been controlled in accordance with the load control information.

18. The method of any one of the preceding claims, wherein the network node (500) comprises a Network Data Analytics Function (NWDAF) 65.

19. A network node (500) configured to: receive load control information identifying a network slice and indicating a target load for the network slice; trigger data collection at a user plane function (UPF) (35) that is in the identified network slice and that has a load above the target load; determine, based on a result of the data collection received from the UPF (35), a policy that achieves the target load at the UPF (35); signal a Policy Control Function (PCF) (50) in the identified network slice to control the load of the UPF (35) in accordance with the policy.

20. The network node of the preceding claim, further configured to perform the method of any one of claims 2-18.

21 . A network node (500) comprising: interface circuitry (520) configured to couple the network node (500) to a wireless communication network (10); processing circuitry (530) communicatively coupled to the interface circuitry (520) and configured to: receive load control information identifying a network slice and indicating a target load for the network slice; trigger data collection at a user plane function (UPF) (35) that is in the identified network slice and that has a load above the target load; determine, based on a result of the data collection received from the UPF (35), a policy that achieves the target load at the UPF (35); signal a Policy Control Function (PCF) (50) in the identified network slice to control the load of the UPF (35) in accordance with the policy.

22. The network node of the preceding claim, wherein the processing circuitry (530) is further configured to perform the method of any one of claims 2-18.

23. A computer program (550), comprising instructions which, when executed on processing circuitry (530) of a network node (500), cause the processing circuitry (530) to carry out the method according to any one of claims 1 -18.

24. A carrier containing the computer program (550) of the preceding claim, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

25. A non-transitory computer readable medium storing a computer program product for controlling a programmable network node (500) in a wireless communication network (10), the computer program product comprising software instructions that, when run on the programmable network node (500), cause the programmable network node (500) to: receive load control information identifying a network slice and indicating a target load for the network slice; trigger data collection at a user plane function (UPF) (35) that is in the identified network slice and that has a load above the target load; determine, based on a result of the data collection received from the UPF (35), a policy that achieves the target load at the UPF (35); signal a Policy Control Function (PCF) (50) in the identified network slice to control the load of the UPF (35) in accordance with the policy.

26. A network node (500) comprising: processing circuitry (530) and a memory (540) communicatively coupled to the processing circuitry (520), wherein the memory (540) contains instructions executable by the processing circuitry (530) whereby the network node (500) is configured to: receive load control information identifying a network slice and indicating a target load for the network slice; trigger data collection at a user plane function (UPF) (35) that is in the identified network slice and that has a load above the target load; determine, based on a result of the data collection received from the UPF (35), a policy that achieves the target load at the UPF (35); signal a Policy Control Function (PCF) (50) in the identified network slice to control the load of the UPF (35) in accordance with the policy.

27. The network node of the preceding claim, wherein the network node (500) is further configured to perform the method of any one of claims 2-18.