Related Applications

[0001] This application claims the benefit of provisional patent application serial number 62/839,329, filed April 26, 2019, the disclosure of which is hereby incorporated herein by reference in its entirety.

Technical Field

[0002] The present disclosure relates to a core network of a cellular

communications system and, more specifically, relates to discovery of a Policy Control Function (PCF) for Access and Mobility (AM) and User Equipment (UE) policies.

Background

[0003] Third Generation Partnership Project (3GPP) has defined the service-based architecture for the Fifth Generation (5G) Core in the 5G system. In Release 15, the service framework consists of Network Function (NF) service consumers and NF service producers. A Network Resource Function (NRF) holds the registry for all services an NF producer has. NF producers, as NF consumers to the NRF, register their NF profile in the NRF. The NF profile contains NF specific information, service instances, addresses to the service instances, etc. (see 3GPP Technical Specification (TS) 29.510 for details). When a NF service consumer wants to access an NF service, the NF service consumer can discover the NF service in the NRF by sending a query. In the response to the query, the NRF includes all NF profiles that match the query. The NF consumer uses the result to select a NF instance and NF service instance. Once a NF service instance is selected, the NF service consumer communicates directly with selected NF service producer instance.

[0004] In 3GPP Release 16, indirect communication is introduced. In indirect communication, there is one or more Service Communication Proxies (SCPs) inserted in the path between the NF service consumer and NF service producer.

[0005] This is an excerpt from TS 23.501 V16.0.2, Annex E, Section E.l :

Option C - Indirect communication without delegated discovery: Consumers do discovery by querying the NRF. Based on discovery result, the consumer does the selection of an NF instance of NF Service instance set The consumer sends the request to the SCP containing the address of the selected service producer pointing to a NF service instance or a set of NF service instances. In the latter case, the

SCP selects an NF Service instance. If possible, the SCP interacts with

NRF to get selection parameters such as location, capacity, etc. The

SCP routes the request to the selected NF service producer instance.

Option D - Indirect communication with delegated discovery:

Consumers do not do any discovery or selection. The consumer adds any necessary discovery and selection parameters required to fmd a suitable producer to the service request. The SCP uses the request address and the discovery and selection parameters in the request message to route the request to a suitable producer instance. The SCP can perform discovery with an NRF and obtain a discovery result.

[0006] In Release 15, the specification states behavior of NF for Policy Control Function (PCF) selection. For the Access and Mobility Management Function (AMF), the following are stated:

• AMF shall select the same PCF NF instance for User Equipment (UE) and Access and Mobility (AM) policy associations.

• AMF in Visited Public Land Mobile Network (VPLMN) may select a PCF in Home Public Land Mobile Network (HPLMN) and send the address to the Visited PCF (V- PCF) (PCF in VPLMN) for UE policies.

• AMF may send the PCF ID to Session Management Function (SMF) when

establishing a Protocol Data Unit (PDU) session.

Summary

[0007] Systems and methods related to delegated Policy Control Function (PCF) discovery in a cellular communications system. In one embodiment, a method for delegated PCF discovery for a roaming scenario in a wireless communication system comprises, at an Access and Mobility Management Function (AMF), sending a first request to a Service Communication Proxy (SCP) to create an Access and Mobility (AM) policy association where the first request comprises an indication that a Home PCF (H- PCF) is needed, and receiving a response to the first request from the SCP where the response comprises an identifier of a selected Visited PCF (V-PCF) and an identifier of a selected H-PCF. The method further comprises, at the SCP, receiving the first request from the AMF to create the AM policy association, discovering and selecting the H-PCF, discovering and selecting the V-PCF, sending a second request to the V-PCF to create the AM policy association, receiving a response to the second request from the V-PCF, and sending the response to the first request to the AMF where the response to the first request comprises the identifier of the V-PCF and the identifier of the FI-PCF.

[0008] Embodiments of a method performed by an AMF are also disclosed. In one embodiment, a method performed by an AMF for delegated PCF discovery for a roaming scenario in a wireless communication system comprises sending a first request to a SCP to create an AM policy association. The first request comprises an indication that a FI- PCF is needed. The method further comprises receiving a response to the first request from the SCP, where the response comprises an identifier of a selected V-PCF and an identifier of a selected FI-PCF.

[0009] In one embodiment, the method further comprises sending a second request to the SCP to create User Equipment (UE) policies, where the second request comprises the identifier of the selected V-PCF and the identifier of the selected FI-PCF, and receiving a response to the second request from the SCP. In one embodiment, the second request is a UE Policy Control Create. In one embodiment, the identifier of the selected FI-PCF is comprised in a message body of the second request. In one embodiment, the identifier of the selected V-PCF is comprised in discovery and selection parameters of the second request.

[0010] In one embodiment, the actions of sending the first request, receiving the response to the first request, sending the second request, and receiving the response to the second request are performed during a PCF discovery procedure in which PCF discovery is delegated to the SCP.

[0011] In one embodiment, the first request is an AM Policy Control Create.

[0012] In one embodiment, the actions of sending the first request and receiving the response to the first request are performed during a PCF discovery procedure in which PCF discovery is delegated to the SCP.

[0013] Corresponding embodiments of a network node that implements an AMF are also disclosed. In one embodiment, a network node that implements an AMF for delegated PCF discovery for a roaming scenario in a wireless communication system is adapted to send a first request to a SCP to create an AM policy association, where the first request comprises an indication that a FI-PCF is needed. The network node is further adapted to receive a response to the first request from the SCP, where the response comprises an identifier of a selected V-PCF and an identifier of a selected H- PCF (228).

[0014] In one embodiment, the network node comprises processing circuitry configured to cause the network node to send the first request to the SCP to create the AM policy association and receive the response to the first request from the SCP.

[0015] Embodiments of a method of operation of a SCP are also disclosed. In one embodiment, a method performed by a SCP for delegated PCF discovery for a roaming scenario in a wireless communication system comprises receiving a first request from an AMF to create an AM policy association, where the first request comprises an indication that a H-PCF is needed. The method further comprises discovering and selecting a H- PCF, discovering and selecting a V-PCF, and sending a second request to the selected V- PCF to create the AM policy association. The method further comprises receiving a response to the second request from the V-PCF and sending a response to the first request to the AMF, where the response to the first request comprises an identifier of the selected V-PCF and an identifier of the selected FI-PCF.

[0016] In one embodiment, the method further comprises receiving a third request from the AMF to create UE policies, where the third request comprises the identifier of the selected V-PCF and the identifier of the selected FI-PCF, and sending a fourth request to the selected V-PCF to create the UE policies, where the fourth request comprises the identifier of the selected FI-PCF. In one embodiment, the method further comprises receiving a fifth request from the selected V-PCF to create the UE policies, where the fifth request comprises the identifier of the selected FI-PCF, and obtaining the UE policies from a core network of a Flome Public Land Mobile Network (FIPLMN) in which the selected FI-PCF is located. In one embodiment, the method further comprises sending a response to the fifth request to the selected V-PCF where the response to the fifth request comprising the UE policies, receiving a response to the fourth request from the selected V-PCF where the response to the fourth request comprises the UE policies, and sending a response to the third request to the AMF where the response to the third request comprises the UE policies. In one embodiment, the fifth request is a UE Policy Control Create. In one embodiment, the third request is a UE Policy Control Create, and the fourth request is a UE Policy Control Create.

[0017] In one embodiment, the first request is an AM Policy Control Create, and the second request is an AM Policy Control Create service operation. [0018] In one embodiment, the method is performed during a PCF discovery procedure in which PCF discovery is delegated to the SCP.

[0019] Corresponding embodiments of a network node that implements a SCP are also disclosed. In one embodiment, a network node that implements a SCP for delegated PCF discovery for a roaming scenario in a wireless communication system is adapted to receive a first request from an AMF to create an AM policy association, where the first request comprises an indication that a FI-PCF is needed. The network node is further adapted to discover and select a FI-PCF, discover and select a V-PCF, send a second request to the selected V-PCF to create the AM policy association, receive a response to the second request from the V-PCF, and send a response to the first request to the AMF, where the response to the first request comprises an identifier of the selected V-PCF and an identifier of the selected FI-PCF.

[0020] In one embodiment, the network node comprises processing circuitry configured to cause the network node to receive the first request from the AMF to create the AM policy association, discover and select the FI-PCF, discover and select the V-PCF, send the second request to the selected V-PCF to create the AM policy association, receive the response to the second request from the V-PCF, and send the response to the first request to the AMF.

Brief Description of the Drawings

[0021] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0022] Figure 1 illustrates one example of a cellular communications system in which embodiments of the present disclosure may be implemented;

[0023] Figure 2 illustrates a Fifth Generation System (5GS) architecture for a roaming scenario with local breakout in which embodiments of the present disclosure may be implemented;

[0024] Figure 3 illustrates the operation of various core network entities to provide delegated discovery of a Policy Control Function (PCF) for Access and Mobility (AM) and User Equipment (UE) policies with delegated discovery in accordance with some embodiments of the present disclosure; and [0025] Figures 4 through 6 are schematic block diagrams of example embodiments of a network node.

Detailed Description

[0026] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0027] Radio Node: As used herein, a "radio node" is either a radio access node or a wireless device.

[0028] Radio Access Node: As used herein, a "radio access node" or "radio network node" is any node in a radio access network of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a 3GPP 5G NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), and a relay node.

[0029] Core Network Entity: As used herein, a "core network entity" is any type of entity in a core network. A core network entity may also sometimes be referred to herein as a "core network node". Some examples of a core network entity include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), or the like in an Evolved Packet Core (EPC). Some other examples of a core network entity include network functions (NFs) such as, e.g., an Access and Mobility Management Function (AMF), a Network Slice Selection Function (NSSF), an Authentication Server Function (AUSF), a UDM, a Session Management Function (SMF), a Policy Control Function (PCF), an AF, a NEF, a User Plane Function (UPF), or the like in a 5G Core (5GC). A core network entity may be implemented as a physical network node (e.g., including hardware or a combination of hardware and software) or implemented as a functional entity (e.g., as software) that is, e.g., implemented on a physical network node or distributed across two or more physical network nodes.

[0030] Wireless Device: As used herein, a "wireless device" is any type of device that has access to a cellular communications network by wirelessly transmitting and/or receiving signals to a radio access node(s). Some examples of a wireless device include, but are not limited to, a User Equipment device in a 3GPP network and a Machine Type Communication device.

[0031] Network Node: As used herein, a "network node" is any node that is either part of the radio access network or the core network of a cellular communications network/system.

[0032] Note that the description given herein focuses on a 3GPP cellular

communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0033] Note that, in the description herein, reference may be made to the term "cell"; however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

[0034] There currently exist certain challenge(s) with respect to PCF selection in the 5GS. One problem is that the AMF does not have the PCF Identity (ID), and the Service Communication Proxy (SCP) does not have context data.

[0035] Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. Systems and methods are disclosed herein for enabling delegated discovery of a PCF for Access and Mobility (AM) and UE policies to work with delegated discovery. In some embodiments, an AMF sends discovery and selection parameters to an SCP. The SCP selects a target NF instance and NF service instance. In case of roaming, the AMF starts with establishing Access and Mobility (AM) policies and indicates to the SCP that an H-PCF is needed (e.g., for UE policies). The SCP discovers a PCF in the Visited Public Land Mobile Network (VPLMN) (i.e., a V-PCF) and an H-PCF in Home Public Land Mobile Network (HPLMN).

In the response to the establishment, the SCP adds the H-PCF ID and PCF ID. The AMF then establishes UE policies, adds the H-PCF ID received in the request body (a parameter among others), and indicates in the discovery and selection parameters the PCF ID that is to be used as V-PCF. When the SCP receives the message including a PCF ID, it will select the PCF with that PCF ID.

[0036] Some embodiments of the present disclosure relate to the order in which the AMF sets up its policy association, the SCP adding PCF ID of both FI-PCF and V-PCF in a first response, and/or the V-PCF adding FI-PCF ID as a discovery and selection parameter.

[0037] Certain embodiments may provide one or more of the following technical advantage(s). Embodiments of the present disclosure enable delegated discovery of PCF for AM and UE policies to work with delegated discovery.

[0038] In this regard, Figure 1 illustrates one example of a cellular communications system 100 according to some embodiments of the present disclosure. In the embodiments described herein, the cellular communications system 100 is a 5G system that includes a 5G NR radio access network (RAN). In this example, the 5G NR RAN includes base stations 102-1 and 102-2, which in 5G NR are referred to as gNBs, controlling corresponding (macro) cells 104-1 and 104-2. The base stations 102-1 and 102-2 are generally referred to herein collectively as base stations 102 and individually as base station 102. Likewise, the cells 104-1 and 104-2 are generally referred to herein collectively as cells 104 and individually as cell 104. The 5G NR RAN may also include a number of low power nodes 106-1 through 106-4 controlling corresponding small cells 108-1 through 108-4. The low power nodes 106-1 through 106-4 can be small base stations (such as pico or femto base stations) or Remote Radio Fleads (RRFIs), or the like. Notably, while not illustrated, one or more of the small cells 108-1 through 108-4 may alternatively be provided by the base stations 102. The low power nodes 106-1 through 106-4 are generally referred to herein collectively as low power nodes 106 and individually as low power node 106. Likewise, the small cells 108-1 through 108-4 are generally referred to herein collectively as small cells 108 and individually as small cell 108. The cellular communications system 100 also includes a core network 110, which in the 5G system is referred to as the 5G core. The base stations 102 (and optionally the low power nodes 106) are connected to the core network 110.

[0039] The base stations 102 and the low power nodes 106 provide service to wireless devices 112-1 through 112-5 in the corresponding cells 104 and 108. The wireless devices 112-1 through 112-5 are generally referred to herein collectively as wireless devices 112 and individually as wireless device 112. The wireless devices 112 are also sometimes referred to herein as UEs.

[0040] Figure 2 illustrates a 5G network architecture for the roaming local-breakout scenario using service-based interfaces between the NFs in the control plane. The service(s) etc. that a NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface. The 5G network architecture of

Figure 2 is one example of the wireless communication system 100 of Figure 1. As illustrated, the architecture includes a Visited Public Land Mobile Network (VPLMN) 200 including the UE(s) 112, the RAN nodes 102, and a number of core network functions.

These core network functions include an AMF 202, an SMF 204, an NSSF 206, a NEF

208, a NRF 210, a PCF 212 (also referred to herein as a "visited PCF" or "V-PCF"), an AF

214, a visited Security Edge Protection Proxy (vSEPP) 216, and a UPF 218. The 5G network architecture of Figure 2 also includes a Home Public Land Mobile Network

(HPLMN) 220 that includes a UDM 222, a NRF 224, an AUSF 226, a PCF 228 (also referred to herein as a "home PCF" or "H-PCF"), a NEF 230, and a home Security Edge

Protection Proxy (hSEPP) 232. In Figure 2, the service based interfaces are indicated by the letter "N" followed by the name of the NF, e.g. Namf for the service based interface of the AMF and Nsmf for the service based interface of the SMF etc.

[0041] As illustrated, the VPLMN 200 may also include a Service Communication

Proxy (SCP) 234. Currently, as described in 3GPP TS 23.501 V16.0.2:

The Service Communication Proxy (SCP) includes one or more of the following functionalities. Some or all of the SCP functionalities may be supported in a single instance of an SCP:

- Indirect Communication (see clause 7.1.1 for details) .

- Delegated Discovery (see clause 7.1.1 for details).

- Message forwarding and routing to destination NF/NF service.

- Communication security (e.g. authorization of the NF Service Consumer to access the NF Service Producer API), load balancing, monitoring, overload control, etc.

- Ability to discover and select one or more UDM(s), AUSF(s), UDR(s), PCF(s) with access to subscription data stored in the UDR based on UE's SUPI, SUCI or GPSI.

NOTE 1: Communication security, e.g. authorization of the NF Service Consumer to access the NF Service Producer's API is specified in TS 33.501 [29].

NOTE 2: Load balancing, monitoring, overload control functionality provided by the SCP is left up to implementation.

The SCP may be deployed in a distributed manner. NOTE 3: More than one SCP can be present in the communication path between NF Services.

[0042] An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

[0043] Figure 3 illustrates the operation of various core network entities to provide delegated discovery of a PCF for AM and UE policies with delegated discovery in accordance with some embodiments of the present disclosure. The steps of Figure 3 are described below.

1. Npcf_AMPolicyControl Create

The AMF 202 adds Discovery and selection parameters (S-NSSAIs, SUPI, H-PCF- flag). More specifically, when performing PCF discovery and selection for the UE 112, the AMF 202 sends an Npcf_AMPolicyControl Create message to the SCP 234 in order to create an AM policy association. In this example, the AMF 202 adds discovery and selection parameters (S-NSSAIs, SUPI, H-PCF-flag in this example) to the Npcf_AMPolicyControl Create message. In some embodiments, the H-PCF-flag provides an indication to the SCP 234 that the H-PCF 228 is needed (e.g., for UE policies). In this manner, the AMF 202 initiates

establishment of AM policies and indicates to the SCP 234 that the H-PCF 228 is needed (e.g., for UE policies). Note that the AMF 202 may decide that the H-PCF 228 is needed based on operator policies.

2. The SCP 234 discovers the V-PCF 212 in the VPLMN 200 and the H-PCF 228 in the HPLMN 220 (e.g., using conventional methods). The SCP 234 selects the H- PCF 228.

3. The SCP 234 selects the V-PCF 212 and sends, to the selected V-PCF 212, an Npcf_AMPolicyControl_Create service operation message in order to create the AM policy association.

4. Npcf_AMPolicyControl Response: The V-PCF 212 sends an Npcf_AMPolicyControl Response message to the SCP 234.

5. Npcf_AMPolicyControl Response

The SCP 234 adds extra parameters (V-PCF ID, H-PCF ID). More specifically, the SCP 234 sends an Npcf_AMPolicyControl Response message to the AMF 202. In this example, the SCP 234 includes additional parameters (V-PCF ID of the selected V-PCF 228 and H-PCF ID of the selected H-PCF 212) in the

Npcf_AMPolicyControl Response message.

6. The AMF 202 puts H-PCF ID in message Body

NpcfJJEPolicyControl Create(H-PCF ID, ...)

The AMF 202 adds Discovery and selection parameters (V-PCF ID)

More specifically, the AMF 202 sends an Npcf_UEPolicyControl Create message to the SCP 234 in order to create a UE policy association, where the

NpcfJJEPolicyControl Create message includes the H-PCF ID received by the AMF 202 from the SCP 234 in step 5. In addition, in this example, the AMF 202 adds discovery and selection parameters (V-PCF ID), e.g., into the

NpcfJJEPolicyControl Create message.

7. The SCP 234 selects the V-PCF 212 with received V-PCF ID

NpcfJJEPolicyControl Create(H-PCF ID, ...)

More specifically, the SCP 234 selects the V-PCF 212 with the V-PCF ID received in step 6 and sends, to the selected V-PCF 212, an Npcf_UEPolicyControl Create message including the H-PCF ID in order to create the UE policy association.

8. NpcfJJEPolicyControl Create

The V-PCF 212 adds Discovery and Selection parameters (H-PCF ID)

More specifically, the V-PCF 212 sends an Npcf_UEPolicyControl Create message to the SCP 234, where the V-PCF 212 includes discovery and selection

parameters (H-PCF ID), e.g., into the Npcf_UEPolicyControl Create message.

9. The SCP 234 forwards the UE Policy Control Create request to the HPLMN 220 according to known principles and receives a response. The response includes the UE policies.

10. NpcfJJEPolicyControl Response. In response to the Npcf_UEPolicyControl Create of step 8, the SCP 234 sends an Npcf_UEPolicyControl Response to the V-PCF 212 including the UE policies.

11. NpcfJJEPolicyControl Response. In response to the Npcf_UEPolicyControl Create of step 7, the V-PCF 212 sends an Npcf_UEPolicyControl Response to the SCF 234 including the UE policies.

12. NpcfJJEPolicyControl Response. In response to the Npcf_UEPolicyControl Create of step 6, the SCP 234 sends an Npcf_UEPolicyControl Response to the AMF 202 including the UE policies. [0044] Figure 4 is a schematic block diagram of a network node 400 according to some embodiments of the present disclosure. The network node 400 may be a radio access node (e.g., a base station) or a network node 400 that implements a core network entity (e.g., AMF, SCF, V-PCF, FI-PCF, or the like). As illustrated, the network node 400 includes a control system 402 that includes one or more processors 404 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory 406, and a network interface 408. The one or more processors 404 are also referred to herein as processing circuitry.

[0045] In addition, if the network node 400 is a radio access node, the network node 400 may also include one or more radio units 410 that each includes one or more transmitters 412 and one or more receivers 414 coupled to one or more antennas 416. The radio units 410 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 410 is external to the control system 402 and connected to the control system 402 via, e.g., a wired connection (e.g., an optical cable).

Flowever, in some other embodiments, the radio unit(s) 410 and potentially the antenna(s) 416 are integrated together with the control system 402.

[0046] The one or more processors 404 operate to provide one or more functions of a network node 400 as described herein (e.g., one or more functions of an AMF, SCF, V- PCF, or FI-PCF as described herein, e.g., with respect to Figure 3). In some

embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 406 and executed by the one or more processors 404.

[0047] Figure 5 is a schematic block diagram that illustrates a virtualized

embodiment of the network node 400 according to some embodiments of the present disclosure. As used herein, a "virtualized" network node is an implementation of the network node 400 in which at least a portion of the functionality of the network node 400 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the network node 400 includes one or more processing nodes 500 coupled to or included as part of a network(s) 502. Each processing node 500 includes one or more processors 504 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 506, and a network interface 508. In addition, if the network node 400 is a radio access node, the network node 400 may also include the control system 402 and/or the one or more radio units 410, as described above.

[0048] In this example, functions 510 of the network node 400 described herein (e.g., one or more functions of an AMF, SCF, V-PCF, or H-PCF as described herein, e.g., with respect to Figure 3) are implemented at the one or more processing nodes 500 or distributed across the control system 402 and the one or more processing nodes 500 in any desired manner. In some particular embodiments, some or all of the functions 510 of the network node 400 described herein (e.g., one or more functions of an AMF, SCF, V-PCF, or H-PCF as described herein, e.g., with respect to Figure 3) are implemented as virtual components executed by one or more virtual machines implemented in a virtual environ ment(s) hosted by the processing node(s) 500.

[0049] In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the network node 400 (e.g., one or more functions of an AMF, SCF, V-PCF, or H-PCF as described herein, e.g., with respect to Figure 3) or a node (e.g., a processing node 500) implementing one or more of the functions 510 of the network node 400 (e.g., one or more functions of an AMF, SCF, V-PCF, or H-PCF as described herein, e.g., with respect to Figure 3) in a virtual environment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0050] Figure 6 is a schematic block diagram of the network node 400 according to some other embodiments of the present disclosure. The network node 400 includes one or more modules 600, each of which is implemented in software. The module(s) 600 provide the functionality of the network node 400 described herein (e.g., one or more functions of an AMF, SCF, V-PCF, or H-PCF as described herein, e.g., with respect to Figure 3). This discussion is equally applicable to the processing node 500 of Figure 5 where the modules 600 may be implemented at one of the processing nodes 500 or distributed across multiple processing nodes 500 and/or distributed across the processing node(s) 500 and the control system 402.

[0051] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.

[0052] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

[0053] Some example embodiments of the present disclosure are as follows.

[0054] Embodiment 1 : A method performed by an Access and Mobility Management Function, AMF, for delegated Policy Control Function, PCF, discovery for a roaming scenario in a wireless communication system, comprising one or more of the following actions: sending (Fig. 3, 1) a first request to a Service Communication Proxy, SCP, to create Access and Mobility, AM, policies, the first request comprising an indication that a Flome PCF, H-PCF, is needed for User Equipment, UE, policies; and receiving (Fig. 3, 5) a response to the first request from the SCP, the response comprising an identifier of a selected Visited PCF, V-PCF, and an identifier of a selected FI-PCF.

[0055] Embodiment 2: The method of embodiment 1 further comprising: sending (Fig. 3, 6) a second request to the SCP to create UE policies, the second request comprising the identifier of the selected V-PCF and the identifier of the selected H-PCF; and receiving (Fig. 3, 12) a response to the second request from the SCP.

[0056] Embodiment 3: The method of embodiment 2 wherein the second request is a UE Policy Control Create. [0057] Embodiment 4: The method of any one of embodiments 1 to 3 wherein the actions of sending the first request and receiving the response to the first request, sending the second request, and receiving the response to the second request are performed during a PCF discovery procedure in which PCF discovery is delegated to the SCP.

[0058] Embodiment 5: The method of any one of embodiments 1 to 4 wherein the first request is an AM Policy Control Create.

[0059] Embodiment 6: The method of any one of embodiments 1 to 5 wherein the actions of sending the first request and receiving the response to the first request are performed during a PCF discovery procedure in which PCF discovery is delegated to the SCP.

[0060] Embodiment 7: A method performed by a Service Communication Proxy, SCP, for delegated Policy Control Function, PCF, discovery for a roaming scenario in a wireless communication system, comprising one or more of the following actions: receiving (Fig. 3, 1) a first request from an Access and Mobility Management Function, AMF, to create Access and Mobility, AM, policies, the first request comprising an indication that a Home PCF, H-PCF, is needed for User Equipment, UE, policies;

discovering and selecting (Fig. 3, 2) an H-PCF; discovering and selecting (Fig. 3, 2-3) a V-PCF; sending (Fig. 3, 3) a second request to the selected V-PCF to create the AM policies; receiving (Fig. 3, 4) a response to the second request from the V-PCF, the response to the second request comprising the AM policies; sending (Fig. 3, 5) a response to the first request to the AMF, the response to the first request comprising the AM policies, an identifier of the selected V-PCF, and an identifier of the selected H- PCF.

[0061] Embodiment 8: The method of embodiment 7 further comprising: receiving (Fig. 3, 6) a third request from the AMF 6o create UE policies, the third request comprising the identifier of the selected V-PCF and the identifier of the selected H-PCF; sending (Fig. 3, 7) a fourth request to the selected V-PCF to create the UE policies, the fourth request comprising the identifier of the selected H-PCF.

[0062] Embodiment 9: The method of embodiment 8 further comprising: receiving (Fig. 3, 8) a fifth request from the selected V-PCF to create the UE policies, the fifth request comprising the identifier of the selected H-PCF; obtaining (Fig. 3, 9) the UE policies from a core network of a Home Public Land Mobile Network, HPLMN, in which the H-PCF is located.

[0063] Embodiment 10: The method of embodiment 9 further comprising: sending (Fig. 3, 10) a response to the fifth request to the selected V-PCF, the response to the fifth request comprising the UE policies; receiving (Fig. 3, 11) a response to the fourth request from the selected V-PCF, the response to the fourth request comprising the UE policies; and sending (Fig. 3, 12) a response to the third request to the AMF, the response to the third request comprising the UE policies.

[0064] Embodiment 11: The method of embodiment 9 or 10 wherein the fifth request is a UE Policy Control Create.

[0065] Embodiment 12: The method of any one of embodiments 8 to 11 wherein the third request is a UE Policy Control Create, and the fourth request is a UE Policy Control Create.

[0066] Embodiment 13: The method of any one of embodiments 7 to 12 wherein the first request is an AM Policy Control Create, and the second request is an AM Policy Control Create service operation.

[0067] Embodiment 14: The method of any one of embodiments 7 to 13 wherein the method is performed during a PCF discovery procedure in which PCF discovery is delegated to the SCP.

[0068] Embodiment 15: A network node for delegated Policy Control Function, PCF, discovery for a roaming scenario in a wireless communication system, the network node implementing a core network entity adapted to perform the method of any one of embodiments 1 to 14.

[0069] Embodiment 16: A network node for delegated Policy Control Function, PCF, discovery for a roaming scenario in a wireless communication system, comprising: a network interface (408, 508); and processing circuitry (404, 504) associated with the network interface (408, 508), the processing circuitry (404, 504) configured to cause the network node to perform the method of any one of embodiments 1 to 14.

[0070] At least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).

• 3GPP Third Generation Partnership Project • 5G Fifth Generation

• 5GC Fifth Generation Core

• 5GS Fifth Generation System

• AF Application Function

• AMF Access and Mobility Function

• AN Access Network

• AP Access Point

• ASIC Application Specific Integrated Circuit

• AUSF Authentication Server Function

• CPU Central Processing Unit

• DN Data Network

• DSP Digital Signal Processor

• eNB Enhanced or Evolved Node B

• EPS Evolved Packet System

• E-UTRA Evolved Universal Terrestrial Radio Access

• FPGA Field Programmable Gate Array

• gNB New Radio Base Station

• gNB-DU New Radio Base Station Distributed Unit

• HSS Home Subscriber Server

• IoT Internet of Things

• IP Internet Protocol

• LTE Long Term Evolution

• MME Mobility Management Entity

• MTC Machine Type Communication

• NEF Network Exposure Function

• NF Network Function

• NR New Radio

• NRF Network Function Repository Function

• NSSF Network Slice Selection Function

• OTT Over-the-Top

• PC Personal Computer

• PCF Policy Control Function

• P-GW Packet Data Network Gateway • QoS Quality of Service

• RAM Random Access Memory

• RAN Radio Access Network

• ROM Read Only Memory

• RRH Remote Radio Head

• RTT Round Trip Time

• SCEF Service Capability Exposure Function

• SMF Session Management Function

• UDM Unified Data Management

• UE User Equipment

• UPF User Plane Function

[0071] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.