URSP rule provisioning in roaming

Abstract

Providing User Equipment (UE) Routing and Selection Policy (URSP) provisioning in roaming is disclosed herein. In one embodiment, a method performed by a visited policy control function (V-PCF) of a visited public land mobile network (VPLMN) includes, in response to UE registration in the VPLMN and establishment of a UE policy association between a home policy control function (H-PCF) of a home public land mobile network (HPLMN) and the V-PCF, receiving HPLMN UE policy subscription data for a registered subscription persistent identifier (SUPI) from the H-PCF, and generating a URSP rule for the UE in the VPLMN. The V-PCF determines, based on the subscription data, whether local offload (LBO) roaming is allowed for a combination of a data network name (DNN) and single network slice selection assistance information (S-NSSAI) in one or more routing selection descriptor (RSD) components in the URSI rule, and if so, transmits the URSI rule to the UE.

Description

Related Applications

[0001] This application claims the benefit of European patent application serial number 22382438.4 filed on May 6, 2022, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates to User Equipment (UE) Routing and Selection Policy (URSP) rule provisioning in a cellular communication system. Background Art

[0003] The 5GC provides policy information from the PCF to the UE. As a non-limiting example, such UE policy information may include different types of policies, such as ANDSP, URSP, V2XP, and ProseP. Figure 1 And the text extracted from 3GPP TR 23.700-85 in Table 1 below describes a problem with URSP in a Visited Public Land Mobile Network (VPLMN): Table 1 Summary of the invention

[0004] Disclosed herein are methods and apparatus for providing User Equipment (UE) Routing and Selection Policy (URSP) provisioning in roaming. Embodiments disclosed herein enable a Visited Policy Control Function (V-PCF) to provide or update URSP rules to a UE while respecting Single Network Slice Selection Assistance Information (S-NSSAI) and Data Network Name (DNN) subscription values, which facilitates successful Protocol Data Unit (PDU) session establishment in Local Breakout (LBO) mode and subscription checks at Access and Mobility Function (AMF) and Session Management Function (SMF).

[0005] Embodiments of a method performed by a Home Policy Control Function (H-PCF) of a Home Public Land Mobile Network (HPLMN) of a cellular communication system for providing URSP rule provisioning in roaming are disclosed herein. The method includes providing HPLMN UE policy subscription data for a Subscription Permanent Identifier (SUPI) to a V-PCF of a Visited Public Land Mobile Network (VPLMN), the HPLMN UE policy subscription data including an indication of whether LBO roaming by the UE is allowed for one or more specified combinations of a DNN and S-NSSAI. Some embodiments may provide that providing the HPLMN UE policy subscription data for the SUPI to the V-PCF is in response to the UE registering in the VPLMN and the UE policy association being established between the H-PCF and the V-PCF. In some embodiments, providing the HPLMN UE policy subscription data for the SUPI to the V-PCF is in response to an update of the UE policy association providing a new Public Land Mobile Network Identifier (PLMN-ID).

[0006] Also disclosed herein is an embodiment of a network node implementing an H-PCF of an HPLMN of a cellular communication system, the network node being used to provide URSP rule provision in roaming. The network node includes one or more transmitters, one or more receivers, and a processing circuit associated with the one or more transmitters and the one or more receivers. The processing circuit is configured to cause the network node to provide HPLMN UE policy subscription data for SUPI to the V-PCF, the HPLMN UE policy subscription data including an indication of whether LBO roaming by the UE is allowed for one or more specified combinations of DNN and S-NSSAI. According to some embodiments, the processing circuit is configured to cause the network node to perform any of the operations attributed to the network node described above.

[0007] Also disclosed herein is an embodiment of a network node implementing an H-PCF of an HPLMN of a cellular communication system, the network node being used to provide URSP rule provision in roaming. The network node is adapted to provide HPLMN UE policy subscription data for SUPI to a V-PCF, the HPLMN UE policy subscription data comprising an indication of whether LBO roaming by the UE is allowed for one or more specified combinations of DNN and S-NSSAI. Some embodiments may provide that the network node is adapted to perform any of the operations attributed to the network node above.

[0008] Also disclosed herein is an embodiment of a method performed by a V-PCF of a VPLMN of a cellular communication system, the method being used to provide URSP rule provision in roaming. The method includes: in response to a UE registering in the VPLMN and a UE policy association being established between an H-PCF of the HPLMN and the V-PCF of the VPLMN, receiving HPLMN UE policy subscription data for a SUPI from the H-PCF. The method also includes generating a URSP rule for the UE in the VPLMN. The method also includes determining, based on the HPLMN UE policy subscription data, whether LBO roaming is allowed for one or more specified combinations of a DNN and S-NSSAI in one or more routing descriptor (RSD) components in the URSP rule. The method additionally includes: in response to determining that LBO roaming is allowed, sending the URSP rule to the UE. In some embodiments, generating a URSP rule for the UE in the VPLMN includes providing a list of policy part identifiers (PSIs), the list of policy part identifiers (PSIs) including an identifier of the VPLMN.

[0009] The present invention also discloses an embodiment of a network node implementing a V-PCF of a VPLMN of a cellular communication system, the network node being used to provide URSP rule provision in roaming. The network node includes one or more transmitters, one or more receivers, and a processing circuit associated with the one or more transmitters and one or more receivers. The processing circuit is configured to cause the network node to receive HPLMN UE policy subscription data for SUPI from the H-PCF in response to the UE registering in the VPLMN and the UE policy association being established between the H-PCF of the HPLMN and the V-PCF of the VPLMN. The processing circuit is also configured to cause the network node to generate URSP rules for the UE in the VPLMN. The processing circuit is also configured to cause the network node to determine, based on the HPLMN UE policy subscription data, whether LBO roaming is allowed for one or more specified combinations of DNN and S-NSSAI in one or more RSD components in the URSP rule. The processing circuit is additionally configured to cause the network node to send URSP rules to the UE in response to determining that LBO roaming is allowed. According to some embodiments, the processing circuit is configured to cause the network node to perform any of the operations attributed to the network node above.

[0010] Also disclosed herein is an embodiment of a network node implementing a V-PCF of a VPLMN of a cellular communication system, the network node being used to provide URSP rule provision in roaming. The network node is adapted to receive HPLMN UE policy subscription data for SUPI from the H-PCF in response to a UE registering in the VPLMN and a UE policy association being established between the H-PCF of the HPLMN and the V-PCF of the VPLMN. The network node is also adapted to generate URSP rules for the UE in the VPLMN. The network node is also adapted to determine, based on the HPLMN UE policy subscription data, whether LBO roaming is allowed for one or more specified combinations of DNN and S-NSSAI in one or more RSD components in the URSP rule. The network node is additionally adapted to send the URSP rules to the UE in response to determining that LBO roaming is allowed. Some embodiments may provide that the network node is adapted to perform any of the operations attributed to the network node described above.

[0011] Also disclosed herein is an embodiment of a method performed by a UE of a cellular communication system for providing URSP rule provision in roaming. The method includes determining whether the S-NSSAI is included in a list of allowed S-NSSAIs based on checking the URSP rule generated by the VPLMN before the URSP rule received from the HPLMN. The method also includes: at least in response to determining that the S-NSSAI is included in the list of allowed S-NSSAIs, determining that the RSD component of the URSP rule generated by the VPLMN is valid.

[0012] In some embodiments, the method further comprises receiving a URSP rule generated by the VPLMN from a V-PCF of the VPLMN. According to some embodiments, the method further comprises registering, by the UE, in the VPLMN, wherein the UE was previously provisioned with the URSP rule generated by the VPLMN by the V-PCF and the URSP rule received from the HPLMN. Some embodiments may provide that the UE was previously provisioned with one of: the URSP rule generated by the VPLMN provided by the V-PCF and the URSP rule received from the HPLMN. In some embodiments, the method further comprises identifying the URSP rule generated by the VPLMN by verifying that the PLMN-ID in the PS I list includes an identifier of the VPLMN.

[0013] Also disclosed herein are embodiments of a UE. The UE includes one or more transmitters, one or more receivers, and a processing circuit associated with the one or more transmitters and the one or more receivers. The processing circuit is configured to cause the UE to determine whether the S-NSSAI is included in the list of allowed S-NSSAIs based on checking the URSP rules generated by the VPLMN before the URSP rules received by the HPLMN. The processing circuit is also configured to cause the UE to at least determine that the RSD component of the URSP rule generated by the VPLMN is valid in response to determining that the S-NSSAI is included in the list of allowed S-NSSAIs. According to some embodiments, the processing circuit is configured to cause the UE to perform any of the operations attributed to the UE above.

[0014] Embodiments of a UE are also disclosed herein. The UE is adapted to determine whether the S-NSSAI is included in the list of allowed S-NSSAIs based on checking the URSP rule generated by the VPLMN before the URSP rule received from the HPLMN. The UE is also adapted to determine that the RSD component of the URSP rule generated by the VPLMN is valid at least in response to determining that the S-NSSAI is included in the list of allowed S-NSSAIs. Some embodiments may provide that the UE is adapted to perform any of the operations attributed to the UE above.

[0015] An embodiment of a cellular communication system is disclosed herein, which includes a network node implementing an H-PCF of an HPLMN, a network node implementing a V-PCF of a VPLMN, and a UE. The network node implementing the H-PCF of the HPLMN is adapted to provide the V-PCF with HPLMN UE policy subscription data for SUPI, the HPLMN UE policy subscription data including an indication as to whether LBO roaming by the UE is allowed for one or more specified combinations of DNN and S-NSSAI. The network node implementing the V-PCF of the VPLMN is adapted to receive the HPLMN UE policy subscription data for SUPI from the H-PCF in response to the UE registering in the VPLMN and the UE policy association being established between the H-PCF of the HPLMN and the V-PCF of the VPLMN. The network node implementing the V-PCF of the VPLMN is also adapted to generate a URSP rule for the UE in the VPLMN. The network node implementing the V-PCF of the VPLMN is further adapted to determine, based on the HPLMN UE policy subscription data, whether LBO roaming is allowed for a specified DNN or one or more specified combinations of a DNN and S-NSSAI in one or more RSD components in the URSP rule. The network node implementing the V-PCF of the VPLMN is additionally adapted to send the URSP rule to the UE in response to determining that LBO roaming is allowed. The UE is adapted to determine whether the S-NSSAI is included in the list of allowed S-NSSAI based on checking the URSP rule generated by the VPLMN received from the V-PCF before the URSP rule received from the HPLMN. The UE is also adapted to determine that the RSD component of the URSP rule generated by the VPLMN is valid in response to at least determining that the S-NSSAI is included in the list of allowed S-NSSAI. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and comprise a part of this specification, illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0017] Figure 1 An exemplary fifth generation (5G) system architecture is shown;

[0018] Figure 2 An example of a cellular communication system according to some embodiments of the present disclosure is shown;

[0019] Figure 3 and Figure 4 Shows Figure 2 The cellular communication system is an example embodiment of a 5G system (5GS);

[0020] Figure 5is a message flow diagram illustrating exemplary communications between and operations performed by an access and mobility function (AMF), a visited policy control function (V-PCF), and a home policy control function (H-PCF) of a cellular communication network, for performing user equipment (UE) policy association establishment when roaming (wherein a visited public land mobile network (VPLMN) provides UE routing and selection policy (URSP) rules);

[0021] Figure 6 is a flow chart illustrating exemplary operations of a UE for providing URSP rule provisioning in roaming;

[0022] Figure 7 is a schematic block diagram of a radio access node according to some embodiments of the present disclosure;

[0023] Figure 8 is a diagram showing some embodiments of the present disclosure Figure 7 A schematic block diagram of an embodiment of a virtualization of a radio access node;

[0024] Fig. 9 According to some other embodiments of the present disclosure Figure 7 A schematic block diagram of a radio access node;

[0025] Fig.10 is a schematic block diagram of a UE device according to some embodiments of the present disclosure; and

[0026] Fig.11 According to some other embodiments of the present disclosure Fig.10 A schematic block diagram of a UE. DETAILED DESCRIPTION

[0027] The embodiments set forth below represent information that enables those skilled in the art to practice the embodiments and illustrate the best mode for practicing the embodiments. After reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and will recognize the application of these concepts that are not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the present disclosure.

[0028] There are certain challenges with existing approaches. In particular, there are public techniques that propose that the V-PCF sends URSP rules to the UE. However, the problem is that a UE attempting to establish a PDU session using the URSP rules provided by the VPLMN will fail, firstly because the UE checks the S-NSSAI in the RSD with the allowed S-NSSAI mapped to the HPLMN S-NSSAI, and secondly because the S-NSSAI and DNN in the PDU session establishment will not pass the subscription check at the AMF and SMF, but will be unknown values ​​to the HPLMN.

[0029] Therefore, the present disclosure and embodiments therein may provide solutions to the above or other challenges. Various embodiments are proposed herein to solve one or more of the problems disclosed herein. Some embodiments provide that when the UE is registered at the VPLMN, the V-PCF sends URSP rules to the UE to route the service. This enables PDU sessions in LBO mode. The URSP rules comply with the subscription information provided by the HPLMN at the UE policy association establishment. The V-PCF needs to have a mapping of the DNN and S-NSSAI values ​​at the VPLMN to the HPLMN values.

[0030] According to some embodiments, when the UE is roaming, the VPLMN may provide the UE with URSP rules in addition to the URSP rules provided by the HPLMN. To achieve this, the following is required: • The HPLMN UE policy subscription data stored in the UDR is extended to indicate the S-NSSAI combination if NLB0 roaming is allowed for a specific DNN. When the UE registers in the VPLMN and the UE policy association is established between the H-PCF and the V-PCF, the UE policy subscription data for the registered SUPI is provided to the V-PCF. The V-PCF may generate URSP rules for UE services in the VPLMN and then check the S-NSSAI in each RSD component in the URSP rules if DNN LBO roaming is allowed. Note that the V-PCF maps the VPLMN DNN and S-NSSAI values ​​to the HPLMN DNN, S-NSSAI values ​​to be able to check the UE policy subscription data. If the subscription check allows, the V-PCF sends the URSP rules to the UE. • The UE checks the URSP rules provided by the VPLMN before the URSP rules provided by the HPLMN. For URSP rules provided by the VPLMN, if the S-NSSAI is in the list of allowed S-NSSAIs, the RSD component is considered valid.

[0031] Certain embodiments may provide one or more of the following technical advantages. Specifically, the embodiments disclosed herein enable the V-PCF to supply or update URSP rules to the UE while complying with the subscription values ​​of the S-NSSAI and DNN, which enables successful PDU session establishment in LBO mode and successful subscription checks at the AMF and SMF.

[0032] Before discussing the method and apparatus for URSP rule provision in roaming in more detail, the terms used herein are first defined as follows:

[0033] Radio Node: As used herein, a "radio node" is a radio access node or a wireless communication device.

[0034] Radio access node: As used herein, a "radio access node" or "radio network node" or "radio access network node" is any node in a radio access network (RAN) of a cellular communication network that operates to wirelessly send and / or receive signals. Some examples of radio access nodes include, but are not limited to: a base station (e.g., a NR base station (gNB) in a 3rd Generation Partnership Project (3GPP) fifth generation (5G) new radio (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, etc.), a relay node, a network node that implements part of the functionality of a base station, or a network node that implements a gNB distributed unit (gNB-DU), or a network node that implements part of the functionality of some other type of radio access node.

[0035] Core network node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of core network nodes include, for example, a mobility management entity (MME), a packet data network gateway (P-GW), a service capability exposure function (SCEF), a home subscriber server (HSS), etc. Some other examples of core network nodes include nodes that implement access and mobility functions (AMF), user plane functions (UPF), session management functions (SMF), authentication server functions (AUSF), network slice selection functions (NSSF), network exposure functions (NEF), network functions (NF) storage functions (NRF), policy control functions (PCF), unified data management (UDM), etc.

[0036] Communication device: As used herein, a "communication device" is any type of device that accesses an access network. Some examples of communication devices include, but are not limited to: mobile phones, smart phones, sensor devices, meters, vehicles, household appliances, medical devices, media players, cameras, or any type of consumer electronic device, such as but not limited to televisions, radios, lighting devices, tablet computers, laptop computers, or personal computers (PCs). A communication device can be a portable, handheld, computer-based, or vehicle-mounted mobile device capable of communicating voice and / or data via a wireless or wired connection.

[0037] Wireless communication device: One type of communication device is a wireless communication device, which may be any type of wireless device that accesses (i.e., is served by) a wireless network (e.g., a cellular network). Some examples of wireless communication devices include, but are not limited to: User Equipment (UE) in a 3GPP network, Machine Type Communication (MTC) devices, and Internet of Things (IoT) devices. Such a wireless communication device may be or may be integrated into a mobile phone, a smart phone, a sensor device, a meter, a vehicle, a home appliance, a medical device, a media player, a camera, or any type of consumer electronic device, such as, but not limited to, a television, a radio, a lighting device, a tablet computer, a laptop computer, or a PC. A wireless communication device may be a portable, handheld, computer-based, or vehicle-mounted mobile device capable of communicating voice and / or data via a wireless connection.

[0038] Network node: As used herein, a "network node" is any node that is part of the RAN or core network of a cellular communication network / system.

[0039] Transmission / Reception Point (TRP): In some embodiments, a TRP can be a network node, a radio head, a spatial relationship, or a transmission configuration indicator (TCI) state. In some embodiments, a TRP can be represented by a spatial relationship or a TCI state. In some embodiments, a TRP can use multiple TCI states. In some embodiments, a TRP can be a part of a gNB that sends / receives radio signals to / from a UE based on physical layer properties and parameters inherent to the element. In some embodiments, in multiple TRP (multi-TRP) operation, a serving cell can schedule UEs from two TRPs, thereby providing better physical downlink shared channel (PDSCH) coverage, reliability, and / or data rate. There are two different operating modes for multiple TRPs: single downlink control information (DCI) and multiple DCI. For both modes, the control of uplink and downlink operations is done by the physical layer and the media access control (MAC). In single DCI mode, the UE is scheduled by the same DCI for both TRPs, and in multi-DCI mode, the UE is scheduled by independent DCI from each TRP.

[0040] In some embodiments, a set of transmission points (TPs) is a set of geographically quasi-co-located transmit antennas (e.g., antenna arrays (having one or more antenna elements)) for one cell, a portion of one cell, or one positioning reference signal (PRS) TP only. The transmission points may include base station (eNB) antennas, remote radio heads (RRHs), remote antennas of base stations, antennas of PRS TPs only, etc. One cell may be formed by one or more TPs. For homogeneous deployments, each TP may correspond to one cell.

[0041] In some embodiments, a set of TRPs is a set of geographically quasi-co-located antennas (e.g., an antenna array (having one or more antenna elements)) that support TP and / or reception point (RP) functionality.

[0042] Note that the description given herein focuses on a 3GPP cellular communication system, and therefore, 3GPP terminology or terminology similar to 3GPP terminology is generally used. However, the concepts disclosed herein are not limited to a 3GPP system.

[0043] Note that in the description of this document, reference is made to the term "cell"; however, particularly with respect to 5G NR concepts, beams may be used instead of cells, and therefore, it is important to note that the concepts described herein apply equally to both cells and beams.

[0044] Figure 2An example of a cellular communication system 200 in which an embodiment of the present disclosure may be implemented is shown. In the embodiments described herein, the cellular communication system 200 is a 5G system (5GS) including a next generation RAN (NG-RAN) and a 5G core (5GC), or an evolved packet system (EPS) including an evolved universal terrestrial RAN (E-UTRAN) and an evolved packet core (EPC). In this example, the RAN includes base stations 202-1 and 202-2, in the 5GS, the base stations 202-1 and 202-2 include NR base stations (gNB) and optional next generation eNBs (ng-eNBs) (e.g., LTE RAN nodes connected to the 5GC), and in the EPS, the base stations 202-1 and 202-2 include eNBs, and the base stations 202-1 and 202-2 control corresponding (macro) cells 204-1 and 204-2. The base stations 202-1 and 202-2 are generally referred to herein as base stations 202 and individually as base stations 202. Likewise, (macro) cells 204-1 and 204-2 are generally referred to herein as (macro) cells 204, and individually as (macro) cells 204. The RAN may also include a plurality of low power nodes 206-1 to 206-4 that control respective small cells 208-1 to 208-4. The low power nodes 206-1 to 206-4 may be small base stations (such as pico or femto base stations) or RRHs, etc. It is noteworthy that, although not shown, one or more of the small cells 208-1 to 208-4 may be provided alternatively by the base station 202. The low power nodes 206-1 to 206-4 are generally referred to herein as low power nodes 206, and individually as low power nodes 206. Likewise, the small cells 208-1 to 208-4 are generally referred to herein as small cells 208, and individually as small cells 208. The cellular communication system 200 also includes a core network 210, which is referred to as 5GC in a 5G system (5GS). The base station 202 (and optionally the low power node 206) is connected to the core network 210.

[0045] Base station 202 and low power node 206 provide services to wireless communication devices 212-1 to 212-5 in corresponding cells 204 and 208. Wireless communication devices 212-1 to 212-5 are generally referred to herein as wireless communication devices 212 and individually as wireless communication devices 212. In the following description, wireless communication device 212 is generally a UE, but the present disclosure is not limited thereto.

[0046] Figure 3 A wireless communication system represented as a 5G network architecture including core network functions (NFs) is shown, where the interaction between any two NFs is represented by point-to-point reference points / interfaces. Figure 3 can be considered as Figure 2 A specific implementation of system 200.

[0047] From the access side, Figure 3 The 5G network architecture shown includes multiple UEs 212 connected to the RAN 202 or access network (AN), and AMF 300. Typically, the RAN 202 includes a base station, such as an eNB or gNB or similar base station. From the core network side, Figure 3 The 5GC NF shown includes NSSF 302 , AUSF 304 , UDM 306 , AMF 300 , SMF 308 , PCF 310 , and application function (AF) 312 .

[0048] The reference point representation of the 5G network architecture is used for the detailed call flow in the development specification standardization. The N1 reference point is defined as the signaling between the bearer UE 212 and the AMF 300. The reference points for the connection between the AN 202 and the AMF 300 and between the AN 202 and the UPF 314 are defined as N2 and N3, respectively. There is a reference point N11 between the AMF 300 and the SMF 308, which means that the SMF 308 is at least partially controlled by the AMF 300. N4 is used by the SMF 308 and the UPF 314 so that the UPF 314 can be set by using a control signal, which is generated by the SMF 308, and the UPF 314 can report its status to the SMF 308. Respectively, N9 is a reference point for the connection between different UPFs 314, and N14 is a reference point for connecting between different AMFs 300. N15 and N7 are defined because PCF 310 applies policies to AMF 300 and SMF 308, respectively. N12 is required for AMF 300 to perform authentication of UE 212. Because subscription data of UE 212 is required for AMF 300 and SMF 308, N8 and N10 are defined.

[0049] The 5GC network is designed to separate UP and CP. In the network, UP carries user services, while CP carries signaling. Figure 3 In the UP, UPF 314 is in the UP, and all other NFs (i.e., AMF 300, SMF 308, PCF 310, AF 312, NSSF 302, AUSF304, and UDM 306) are in the CP. Separating UP and CP ensures that each plane resource is scaled independently. It also allows the UPF to be deployed separately from the CP function in a distributed manner. In this architecture, for some applications requiring low latency, the UPF can be deployed very close to the UE to shorten the round trip time (RTT) between the UE and the data network.

[0050] The core 5G network architecture includes modular functions. For example, AMF 300 and SMF 308 are independent functions in CP. Separating AMF 300 and SMF 308 allows independent evolution and scaling. Other CP functions like PCF 310 and AUSF 304 can be Figure 3 The modular functional design enables the 5GC network to flexibly support various services.

[0051] Each NF interacts directly with another NF. Intermediate functions can be used to route messages from one NF to another. In CP, a set of interactions between two NFs is defined as a service so that its reuse is possible. The service implements support for modularization. UP supports interactions between different UPFs such as forwarding operations.

[0052] Figure 4 The following 5G network architecture is shown, which uses a service-based interface between NFs in the CP instead of Figure 3 Point-to-point reference points / interfaces used in the 5G network architecture. Figure 3 The NF described corresponds to Figure 4 The services provided by NF to other authorized NFs can be exposed to authorized NFs through service-based interfaces. Figure 4 In the specification, the service-based interface is indicated by the letter “N” followed by the name of the NF, for example, Namf for the service-based interface of AMF 300 and Nsmf for the service-based interface of SMF 308, etc. Figure 4 The NEF 400 and NRF402 are not shown in Figure 3 However, it should be clear that Figure 3 All NFs depicted in Figure 4 The NEF 400 and NRF 402 interact, although in Figure 3 Not explicitly indicated.

[0053] Figure 3 and Figure 4Some characteristics of the NFs shown in FIG300 can be described in the following manner. AMF 300 provides UE-based authentication, authorization, mobility management, etc. Even UE 212 using multiple access technologies is basically connected to a single AMF 300 because AMF 300 is independent of access technology. SMF 308 is responsible for session management and allocates an Internet Protocol (IP) address to the UE. SMF 308 also selects and controls UPF 314 for data transmission. If UE 212 has multiple sessions, different SMFs 308 can be assigned to each session to manage them separately, and each session may provide different functions. AF 312 provides information about packet flows to PCF 310 responsible for policy control in order to support QoS. Based on this information, PCF 310 determines policies on mobility and session management so that AMF 300 and SMF 308 operate correctly. AUSF 304 supports authentication functions for UE or similar devices, and therefore stores data for authentication of UE or similar devices, while UDM 306 stores subscription data of UE 212. A data network (DN) that is not part of the 5GC network provides Internet access or operator services or similar services.

[0054] NFs may be implemented as network elements on dedicated hardware, or as software instances running on dedicated hardware, or as virtualized functions instantiated on a suitable platform (e.g., cloud infrastructure).

[0055] Embodiments for providing URSP rule provisioning in roaming are now discussed. In this regard, Figure 5 A message flow diagram is provided that illustrates exemplary communications between and operations performed by the AMF, V-PCF, and H-PCF of a cellular communication network for performing UE policy association establishment when roaming (wherein the VPLMN provides URSP rules). Figure 5 The procedure shown adopts the UE Policy Association Establishment procedure performed in the roaming case as specified in clause 4.16.11 of TS 23.502: Step 502, step 504 and step 506 are the same as step 1, step 2 and step 3 in clause 4.16.11 of TS23.502. Step 508 is the same as step 4 in clause 4.16.11 of TS 23.502, but additionally, the H-PCF may include the S-NSSAI subscription information defined in Table 2 below. The S-NSSAI subscription information is stored at the UDR of the HPLMN and provided to the H-PCF. The H-PCF sends the S-NSSAI subscription information to the VPLMN based on a local policy that states whether the VPLMN can provide URSP rules to the UE and whether LBO roaming is allowed. The H-PCF provides the S-NSSAI subscription information only for the DNN or the (S-NSSAI and DNN) combination, and the S-NSSAI subscription information has the LBO roaming allowed setting. Step 510 is the same as step 4 in clause 4.16.11 of TS 23.502, but additionally the V-PCF stores the S-NSSAI subscription information as part of the UE context and may provide an additional PCRT to the AMF. • With respect to steps 512a, 514 and 516, the (H-)PCF may create a UE policy container to be sent to the UE, as defined in steps 7 and 8 in 4.16.11 of TS 23.502. ·In step 512b, if the subscription information allows LBO roaming for those DNNs, S-NNSAIs in the RSD component, the (V-)PCF may create a UE policy container to be delivered to the UE. Because the AF defined in clause 6.6 of TS 23.548 provides application guidance for URSP rule determination for "any UE", or because of local policy at the V-PCF, the V-PCF generates URSP rules for services to be offloaded at the VPLMN. The V-PCF may decide to offload application services to a certain DNN, S-NSSAI (e.g., based on the load in the network, which may be derived from analysis at a specific time of the day). The V-PCF provides a PSI list The PSI list includes the VPLMN ID to identify it at the UE. Note that if step 512b occurs, it occurs at any time after step 510. • At step 518, the (V-)PCF triggers the UE configuration update procedure to send the UE policy container as defined in step 8 of clause 4.5.11 of TS 23.502. • At step 520, the V-PCF checks whether the Notify Response is processed locally or is to be sent to the H-PCF, if so, step 9 in clause 4.5.11 of TS 23.502 occurs. • Step 522 is the same as step 10 in H-PCF clause 4.5.11 of TS 23.502. Table 2

[0056] Figure 6 A flow chart is provided illustrating exemplary operations of a UE for performing URSP rule provisioning in roaming. Figure 6 The operations in begin with the UE receiving a URSP rule from a V-PCF of a VPLMN (block 600). In some embodiments, the UE identifies the URSP rule received from the V-PCF by verifying that a public land mobile network identifier (PLMN-ID) in a policy part identifier (PSI) list includes an identifier of the VPLMN (block 602). The UE determines whether the S-NSSAI is included in a list of allowed S-NSSAIs based on checking the URSP rule received from the V-PCF prior to the URSP rule received from the HPLMN (block 604). In response to determining that the S-NSSAI is included in the list of allowed S-NSSAIs, the UE determines that the RSD component of the URSP rule is valid (block 606).

[0057] Figure 7 is a schematic block diagram of a radio access node 700 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The radio access node 700 may be, for example, a base station 202 or a base station 206 or a network node that implements all or part of the functionality of a base station 202 or a gNB described herein. As shown, the radio access node 700 includes a control system 702, which includes one or more processors 704 (e.g., a central processing unit (CPU), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc.), a memory 706, and a network interface 708. The one or more processors 704 are also referred to herein as processing circuits. Additionally, the radio access node 700 may include one or more radio units 710, each of which includes one or more transmitters 712 and one or more receivers 714 coupled to one or more antennas 716. The radio unit 710 may be referred to as a radio interface circuit or a part of a radio interface circuit. In some embodiments, the (multiple) radio units 710 are external to the control system 702 and connected to the control system 702, for example via a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) 710 and possible antenna(s) 716 are integrated with the control system 702. The one or more processors 704 operate to provide one or more functions of the radio access node 700 as described herein. In some embodiments, the functions are implemented by software, which is stored, for example, in the memory 706 and executed by the one or more processors 704.

[0058] Figure 8700 is a schematic block diagram showing a virtualized embodiment of a radio access node 700 according to some embodiments of the present disclosure. The discussion is equally applicable to other types of network nodes. In addition, other types of network nodes may have similar virtualized architectures. Similarly, optional features are represented by dashed boxes.

[0059] As used herein, a "virtualized" radio access node is an implementation of a radio access node 700 in which at least a portion of the functionality of the radio access node 700 is implemented as a virtual component (e.g., via a virtual machine executing on a physical processing node in a network). As shown, in this example, as described above, the radio access node 700 may include a control system 702 and / or one or more radio units 710. The control system 702 may be connected to the radio unit(s) 710 via, for example, an optical cable or similar medium. The radio access node 700 includes one or more processing nodes 800 coupled to or included as part of a network(s) 802. If present, the control system 702 or the radio unit is connected to the processing node(s) 800 via the network 802. Each processing node 800 includes one or more processors 804 (e.g., CPUs, ASICs, FPGAs, and / or similar processors), a memory 806, and a network interface 808.

[0060] In this example, the functionality 810 of the radio access node 700 described herein is implemented at one or more processing nodes 800, or distributed in any desired manner across one or more processing nodes 800 and the control system 702 and / or the radio unit(s) 710. In some specific embodiments, some or all of the functionality 810 of the radio access node 700 described herein are implemented as virtual components that are executed by one or more virtual machines implemented in a virtual environment hosted by the processing node(s) 800. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 800 and the control system 702 is used in order to perform at least some of the desired functionality 810. It is worth noting that in some embodiments, the control system 702 may not be included, in which case the radio unit(s) 710 communicates directly with the processing node(s) 800 via an appropriate network interface.

[0061] In some embodiments, a computer program including instructions is provided, which, when executed by at least one processor, causes the at least one processor to perform the functions of the radio access node 700 or a node (e.g., processing node 800) that implements one or more of the functions 810 of the radio access node 700 in a virtual environment according to any embodiment described herein. In some embodiments, a carrier including the above-mentioned computer program product is provided. The carrier is one of an electric signal, an optical signal, a radio signal, or a computer-readable storage medium (e.g., a non-transitory computer-readable medium, such as a memory).

[0062] Fig. 9 is a schematic block diagram of a radio access node 700 according to some other embodiments of the present disclosure. The radio access node 700 includes one or more modules 900, each of which is implemented in software. The (multiple) modules 900 provide the functionality of the radio access node 700 described herein. The discussion also applies to Figure 8 800 , where module 900 may be implemented at one of processing nodes 800 , distributed across multiple processing nodes 800 , and / or distributed across processing nodes 800 and control system 702 .

[0063] Fig.10 1 is a schematic block diagram of a wireless communication device 1000 according to some embodiments of the present disclosure. As shown, the wireless communication device 1000 includes one or more processors 1002 (e.g., CPU, ASIC, FPGA and / or similar processors), a memory 1004, and one or more transceivers 1006, each transceiver 1006 including one or more transmitters 1008 and one or more receivers 1010 coupled to one or more antennas 1012. The (multiple) transceivers 1006 include radio front-end circuits connected to the (multiple) antennas 1012, and as will be understood by those of ordinary skill in the art, the radio front-end circuits are configured to condition signals communicated between the (multiple) antennas 1012 and the (multiple) processors 1002. The processor 1002 is also referred to herein as a processing circuit. The transceiver 1006 is also referred to herein as a radio circuit. In some embodiments, the functionality of the wireless communication device 1000 described above may be implemented in whole or in part in software, which is, for example, stored in the memory 1004 and executed by the processor 1002. Note that the wireless communication device 1000 may include Fig.10 Additional components not shown, such as one or more user interface components (e.g., input / output interfaces including displays, buttons, touch screens, microphones, speakers, etc. and / or similar components and / or any other components for allowing input of information to the wireless communication device 1000 and / or any other components for allowing output of information from the wireless communication device 1000), a power source (e.g., a battery and associated power circuitry), etc.

[0064] In some embodiments, a computer program including instructions is provided, which, when executed by at least one processor, causes the at least one processor to perform the functions of the wireless communication device 1000 according to any embodiment described herein. In some embodiments, a carrier including the above-mentioned computer program product is provided. The carrier is one of an electric signal, an optical signal, a radio signal, or a computer-readable storage medium (e.g., a non-transitory computer-readable medium, such as a memory).

[0065] Fig.11 1 is a schematic block diagram of a wireless communication device 1000 according to some other embodiments of the present disclosure. The wireless communication device 1000 includes one or more modules 1100, each of which is implemented in software. The (multiple) modules 1100 provide the functions of the wireless communication device 1000 described herein.

[0066] Any suitable steps, methods, features, functions or benefits disclosed herein may be performed by one or more functional units or modules of one or more virtual devices. Each virtual device may include a plurality of these functional units. These functional units may be implemented via a processing circuit, which may include one or more microprocessors or microcontrollers and other digital hardware, and other digital hardware may include a digital signal processor (DSP), dedicated digital logic, etc. The processing circuit may be configured to execute program codes stored in a memory, which may include one or more types of memory, such as a read-only memory (ROM), a random access memory (RAM), a cache memory, a flash memory device, an optical storage device, etc. The program code stored in the memory includes program instructions for executing one or more telecommunications and / or data communication protocols and instructions for executing one or more techniques described herein. In some implementations, the processing circuit may be used to cause the corresponding functional unit to perform the corresponding functions according to one or more embodiments of the present invention.

[0067] Although the processes in the accompanying figures may show a specific order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (for example, alternative embodiments may perform operations in a different order, combine certain operations, overlap certain operations, etc.).

[0068] Some example embodiments of the present disclosure are provided below, but are not limited thereto.

[0069] Embodiment 1: A method executed by a home policy control function H-PCF of a home public land mobile network HPLMN of a cellular communication system, the method being used to provide user equipment UE routing and selection policy URSP rule provision and roaming, the method comprising: In response to the UE registering in a visited public land mobile network VPLMN and a UE policy association being established between the H-PCF and a visited policy control function V-PCF of the VPLMN, providing the V-PCF with HPLMN UE policy subscription data for a registered subscription permanent identifier SUPI, the HPLMN UE policy subscription data comprising an indication as to whether local offload (LBO) roaming by the UE is allowed for a specified combination of a data network name DNN and single network slice selection assistance information S-NSSAI.

[0070] Embodiment 2: A network node implementing a home policy control function H-PCF of a home public land mobile network HPLMN, the network node is used to provide user equipment UE routing and selection policy URSP rule provision and roaming, the network node includes: One or more transmitters; One or more receivers; and processing circuitry associated with the one or more transmitters and the one or more receivers, the processing circuitry being configured to cause the network node to: In response to the UE registering in a visited public land mobile network VPLMN and a UE policy association being established between the H-PCF and a visited policy control function V-PCF of the VPLMN, providing the V-PCF with HPLMN UE policy subscription data for a registered subscription permanent identifier SUPI, the HPLMN UE policy subscription data comprising an indication as to whether local offload (LBO) roaming by the UE is allowed for a specified combination of a data network name DNN and single network slice selection assistance information S-NSSAI.

[0071] Embodiment 3: A network node implementing a home policy control function H-PCF of a home public land mobile network HPLMN, the network node is used to provide user equipment UE routing and selection policy URSP rule provision and roaming, the network node is used to: In response to the UE registering in a visited public land mobile network VPLMN and a UE policy association being established between the H-PCF and a visited policy control function V-PCF of the VPLMN, providing the V-PCF with HPLMN UE policy subscription data for a registered subscription permanent identifier SUPI, the HPLMN UE policy subscription data comprising an indication as to whether local offload (LBO) roaming by the UE is allowed for a specified combination of a data network name DNN and single network slice selection assistance information S-NSSAI.

[0072] Embodiment 4: A method performed by a visited policy control function V-PCF of a visited public land mobile network VPLMN, the method being used to provide a user equipment UE routing and selection policy URSP rule provision and roaming, the method comprising: in response to the UE registering in the VPLMN and a UE policy association being established between the home public land mobile network HPLMN and the V-PCF of the VPLMN, receiving from the H-PCF the HPLMN UE policy subscription data for the registered subscription permanent identifier SUPI; Generate URSP rules for the UE in the VPLMN; determining, based on the HPLMN UE policy subscription data, whether local offload (LBO) roaming is allowed for a specified combination of a data network name (DNN) and single network slice selection assistance information (S-NSSAI) in one or more routing descriptor (RSD) components in a URSP rule; and In response to determining that LBO roaming is allowed, sending URSP rules to the UE.

[0073] Embodiment 5: According to the method of embodiment 4, generating the URSP rule for the UE in the VPLMN includes: providing a list of policy part identifiers PSI, wherein the list of policy part identifiers PSI includes an identifier of the VPLMN.

[0074] Embodiment 6: A network node implementing a visiting policy control function V-PCF of a visited public land mobile network VPLMN of a cellular communication system, the network node is used to provide user equipment UE routing and selection policy URSP rule provision and roaming, the network node comprising: One or more transmitters; One or more receivers; and processing circuitry associated with the one or more transmitters and the one or more receivers, the processing circuitry being configured to cause the network node to: in response to the UE registering in the VPLMN and a UE policy association being established between the home public land mobile network HPLMN and the V-PCF of the VPLMN, receiving from the H-PCF the HPLMN UE policy subscription data for the registered subscription permanent identifier SUPI; Generate URSP rules for the UE in the VPLMN; determining whether local offload (LBO) roaming is allowed for a specified combination of a data network name (DNN) and single network slice selection assistance information (S-NSSAI) in one or more routing descriptor (RSD) components in a URSP rule based on the HPLMN UE policy subscription data; and In response to determining that LBO roaming is allowed, sending URSP rules to the UE.

[0075] Embodiment 7: The network node according to embodiment 6, wherein the processing circuit is further configured to cause the network node to execute the method of embodiment 5.

[0076] Embodiment 8: A network node implementing a visiting policy control function V-PCF of a visited public land mobile network VPLMN of a cellular communication system, the network node is used to provide user equipment UE routing and selection policy URSP rule provision and roaming, the network node is adapted to: in response to the UE registering in the VPLMN and a UE policy association being established between the home public land mobile network HPLMN and the V-PCF of the VPLMN, receiving from the H-PCF the HPLMN UE policy subscription data for the registered subscription permanent identifier SUPI; Generate URSP rules for the UE in the VPLMN; determining whether local offload (LBO) roaming is allowed for a specified combination of a data network name (DNN) and single network slice selection assistance information (S-NSSAI) in one or more routing descriptor (RSD) components in a URSP rule based on the HPLMN UE policy subscription data; and In response to determining that LBO roaming is allowed, sending URSP rules to the UE.

[0077] Embodiment 9: The network node as described in Embodiment 8, wherein the network node is further adapted to execute the method of Embodiment 5.

[0078] Embodiment 10: A method performed by a user equipment UE in a cellular communication system, the method being used to provide UE routing and selection policy URSP rule provision and roaming, the method comprising: · receiving URSP rules from a Visiting Policy Control Function V-PCF of a Visited Public Land Mobile Network VPLMN; determining whether the single network slice selection assistance information S-NSSAI is contained within the list of allowed S-NSSAI based on checking the URSP rules received from the V-PCF prior to the URSP rules received from the home public land mobile network HPLMN; and In response to determining that the S-NSSAI is contained within the list of allowed S-NSSAIs, determining that the routing descriptor, RSD, component of the URSP rule is valid.

[0079] Embodiment 11: The method according to embodiment 10 further includes: identifying the URSP rule received from the V-PCF by verifying that the public land mobile network identifier PLMN-ID in the policy part identifier PSI list includes an identifier of the VPLMN.

[0080] Embodiment 12: A user equipment UE, comprising: One or more transmitters; One or more receivers; and processing circuitry associated with the one or more transmitters and the one or more receivers, the processing circuitry being configured to cause the UE to: Receive UE routing and selection policy URSP rules from the Visiting Policy Control Function V-PCF of the Visited Public Land Mobile Network VPLMN; determining whether the single network slice selection assistance information S-NSSAI is contained within the list of allowed S-NSSAI based on checking the URSP rules received from the V-PCF prior to the URSP rules received from the home public land mobile network HPLMN; and In response to determining that the S-NSSAI is contained within the list of allowed S-NSSAIs, determining that the routing descriptor, RSD, component of the URSP rule is valid.

[0081] Embodiment 13: The UE according to embodiment 11, wherein the processing circuit is further configured to cause the UE to execute the method of embodiment 11.

[0082] Embodiment 14: A user equipment UE is adapted to: Receive UE routing and selection policy URSP rules from the Visiting Policy Control Function V-PCF of the Visited Public Land Mobile Network VPLMN; determining whether the single network slice selection assistance information S-NSSAI is contained within the list of allowed S-NSSAI based on checking the URSP rules received from the V-PCF prior to the URSP rules received from the home public land mobile network HPLMN; and In response to determining that the S-NSSAI is contained within the list of allowed S-NSSAIs, determining that the routing descriptor, RSD, component of the URSP rule is valid.

[0083] Embodiment 15: The UE according to embodiment 14, wherein the UE is further adapted to execute the method of embodiment 11.

[0084] Embodiment 16: A cellular communication system, comprising a network node implementing a home policy control function H-PCF of a home public land mobile network HPLMN, a network node implementing a visiting policy control function V-PCF of a visited public land mobile network VPLMN, and a user equipment UE, wherein: the network node implementing the H-PCF of the HPLMN is adapted to: in response to the UE registering in the VPLMN and a UE policy association being established between the H-PCF and the V-PCF of the VPLMN, providing the V-PCF with HPLMN UE policy subscription data for a registered subscription permanent identifier SUPI, the HPLMN UE policy subscription data comprising an indication as to whether local offload (LBO) roaming by the UE is allowed for a specified combination of a data network name (DNN) and single network slice selection assistance information (S-NSSAI); The network node implementing the V-PCF of the VPLMN is adapted to: receiving, in response to the UE registering in the VPLMN and a UE policy association being established between the H-PCF of the HPLMN and the V-PCF of the VPLMN, the HPLMN UE policy subscription data for the SUPI from the H-PCF; Generate URSP rules for the UE in the VPLMN; Determining, based on the HPLMN UE policy subscription data, whether local offload (LBO) roaming is allowed for a specified DNN or a specified combination of a DNN and S-NSSAI in one or more routing descriptor (RSD) components in the URSP rule; In response to determining that LBO roaming is allowed, sending URSP rules to the UE; and The UE is adapted to: Receive URSP rules from the V-PCF of the VPLMN; determining whether the S-NSSAI is contained in a list of allowed S-NSSAIs based on checking the URSP rules received from the V-PCF prior to the URSP rules received from the HPLMN; and In response to determining that the S-NSSAI is contained within the list of allowed S-NSSAIs, determining that the RSD component of the URSP rule is valid.

[0085] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein.

Claims

1. A method performed by a Home Policy Control Function (H-PCF) of a Home Public Land Mobile Network (HPLMN) of a cellular communication system (200), the method being used to provide a User Equipment (UE) routing and selection policy (URSP) rule provision in roaming, the method comprising: The HPLMN UE policy subscription data for a subscription permanent identifier SUPI is provided (508) to a visited policy control function V-PCF of a visited public land mobile network VPLMN, the HPLMN UE policy subscription data comprising an indication as to whether local offload (LBO) roaming by the UE is allowed for one or more specified combinations of a data network name DNN and single network slice selection assistance information S-NSSAI.

2. The method of claim 1 , wherein the HPLMN UE policy subscription data for the SUPI is provided to the V-PCF in response to the UE registering in the VPLMN and a UE policy association being established between the H-PCF and the V-PCF.

3. The method of claim 1 , wherein the HPLMN UE policy subscription data for the SUPI is provided to the V-PCF in response to an update of the UE policy association providing a new Public Land Mobile Network Identifier PLMN-ID.

4. A network node (700) implementing a home policy control function H-PCF of a home public land mobile network HPLMN of a cellular communication system (200), the network node (700) being used to provide user equipment UE routing and selection policy URSP rule supply during roaming, the network node comprising: one or more transmitters (712); one or more receivers (714); as well as A processing circuit (704) associated with the one or more transmitters and the one or more receivers, the processing circuit being configured to cause the network node to provide (508) to a visit policy control function V-PCF HPLMN UE policy subscription data for a subscription permanent identifier SUPI, the HPLMN UE policy subscription data comprising an indication as to whether local breakout (LBO) roaming by the UE is allowed for one or more specified combinations of a data network name DNN and single network slice selection assistance information S-NSSAI.

5. The network node according to claim 4, wherein the processing circuit is configured to perform the operations according to any one of claims 2 to 3.

6. A network node (700) implementing a home policy control function H-PCF of a home public land mobile network HPLMN of a cellular communication system (200), the network node (700) being used to provide user equipment UE routing and selection policy URSP rule supply in roaming, the network node being adapted to provide (508) a visit policy control function V-PCF with HPLMN UE policy subscription data for a subscription permanent identifier SUPI, the HPLMN UE policy subscription data comprising an indication as to whether local breakout LBO roaming performed by the UE is allowed for one or more specified combinations of a data network name DNN and single network slice selection assistance information S-NSSAI.

7. The network node according to claim 6, wherein the network node is adapted to perform the operations according to any one of claims 2 to 3.

8. A method performed by a Visiting Policy Control Function (V-PCF) of a Visited Public Land Mobile Network (VPLMN) of a cellular communication system (200), the method being used to provide User Equipment (UE) routing and selection policy (URSP) rule provision in roaming, the method comprising: receiving (508) HPLMN UE policy subscription data for a subscription permanent identifier SUPI from the H-PCF in response to the UE being registered in the VPLMN and a UE policy association being established between a home policy control function H-PCF of a home public land mobile network HPLMN and the V-PCF of the VPLMN; generating (512b) URSP rules for the UE in the VPLMN; determining (512b) based on the HPLMN UE policy subscription data, whether local offload (LBO) roaming is allowed for one or more specified combinations of a data network name (DNN) and single network slice selection assistance information (S-NSSAI) in one or more routing descriptor (RSD) components in the URSP rule; as well as In response to determining that LBO roaming is allowed, the URSP rules are sent (518) to the UE.

9. The method of claim 8, wherein generating the URSP rules for the UE in the VPLMN comprises providing a list of policy part identifiers (PSIs), the list of PSIs comprising an identifier of the VPLMN.

10. A network node (700) implementing a visiting policy control function (V-PCF) of a visited public land mobile network (VPLMN) of a cellular communication system (200), the network node (700) being used to provide a user equipment (UE) routing and selection policy (URSP) rule supply in roaming, the network node comprising: one or more transmitters (712); one or more receivers (714); as well as processing circuitry (704) associated with the one or more transmitters and the one or more receivers, the processing circuitry being configured to cause the network node to: receiving (508) HPLMN UE policy subscription data for a subscription permanent identifier SUPI from the H-PCF in response to the UE being registered in the VPLMN and a UE policy association being established between a home policy control function H-PCF of a home public land mobile network HPLMN and the V-PCF of the VPLMN; generating (512b) URSP rules for the UE in the VPLMN; determining (512b) based on the HPLMN UE policy subscription data, whether local offload (LBO) roaming is allowed for one or more specified combinations of a data network name (DNN) and single network slice selection assistance information (S-NSSAI) in one or more routing descriptor (RSD) components in the URSP rule; as well as In response to determining that LBO roaming is allowed, the URSP rules are sent (518) to the UE. 11 . The network node according to claim 10 , wherein the processing circuit is further configured to cause the network node to perform the method according to claim 9 .

12. A network node (700) implementing a visiting policy control function (V-PCF) of a visited public land mobile network (VPLMN) of a cellular communication system (200), the network node (700) being used to provide a user equipment (UE) routing and selection policy (URSP) rule provision in roaming, the network node being adapted to: receiving (508) HPLMN UE policy subscription data for a subscription permanent identifier SUPI from the H-PCF in response to the UE being registered in the VPLMN and a UE policy association being established between a home policy control function H-PCF of a home public land mobile network HPLMN and the V-PCF of the VPLMN; generating (512b) URSP rules for the UE in the VPLMN; determining (512b) based on the HPLMN UE policy subscription data, whether local offload (LBO) roaming is allowed for one or more specified combinations of a data network name (DNN) and single network slice selection assistance information (S-NSSAI) in one or more routing descriptor (RSD) components in the URSP rule; as well as In response to determining that LBO roaming is allowed, the URSP rules are sent (518) to the UE.

13. The network node according to claim 12, wherein the network node is further adapted to perform the method according to claim 9.

14. A method performed by a user equipment UE (1000) of a cellular communication system (200), the method being used to provide UE routing and selection policy URSP rules in roaming, the method comprising: determining (604) whether single network slice selection assistance information S-NSSAI is contained in a list of allowed S-NSSAIs based on checking the URSP rules generated by the visited public land mobile network VPLMN prior to the URSP rules received from the home public land mobile network HPLMN; as well as In response to at least determining that the S-NSSAI is included in the list of allowed S-NSSAIs, determining (606) that a routing descriptor, RSD component of the URSP rule generated by the VPLMN is valid.

15. The method according to claim 14, further comprising receiving (600) the URSP rule generated by the VPLMN from a Visiting Policy Control Function (V-PCF) of the VPLMN.

16. The method according to claim 14, further comprising registering, by the UE, in the VPLMN; The UE is previously provisioned with the URSP rules generated by the VPLMN and provided by a visiting policy control function V-PCF of the VPLMN, and the URSP rules received from the HPLMN.

17. The method of claim 14, wherein the UE is previously provisioned with one of: a URSP rule generated by the VPLMN provided by a Visiting Policy Control Function (V-PCF) of the VPLMN, and the URSP rule received from the HPLMN.

18. The method of claim 14, further comprising identifying (602) the URSP rule generated by the VPLMN by verifying that a Public Land Mobile Network Identifier PLMN-ID in a list of a Policy Part Identifier (PSI) includes an identifier of the VPLMN.

19. A user equipment UE (1000), comprising: one or more transmitters (1008); one or more receivers (1010); as well as A processing circuit (1002) associated with the one or more transmitters and the one or more receivers, the processing circuit being configured to cause the UE to: determining (604) whether single network slice selection assistance information S-NSSAI is contained in a list of allowed S-NSSAIs based on checking URSP rules generated by a visited public land mobile network VPLMN prior to UE routing and selection policy URSP rules received from a home public land mobile network HPLMN; as well as In response to at least determining that the S-NSSAI is included in the list of allowed S-NSSAIs, determining (606) that a routing descriptor, RSD component of the URSP rule generated by the VPLMN is valid.

20. The UE according to claim 19, wherein the processing circuit is further configured to cause the UE to perform the method according to any one of claims 15 to 18.

21. A user equipment UE (1000), adapted to: determining (604) whether single network slice selection assistance information S-NSSAI is contained in a list of allowed S-NSSAI based on checking URSP rules generated by the visited public land mobile network VPLMN prior to UE routing and selection policy URSP rules received from the home public land mobile network HPLMN; and In response to at least determining that the S-NSSAI is included in the list of allowed S-NSSAIs, determining (606) that a routing descriptor, RSD component of the URSP rule generated by the VPLMN is valid.

22. The UE according to claim 21, wherein the UE is further adapted to perform the method according to any one of claims 15 to 18.

23. A cellular communication system (200), comprising a network node (700) implementing a home policy control function H-PCF of a home public land mobile network HPLMN, a network node (700) implementing a visiting policy control function V-PCF of a visited public land mobile network VPLMN, and a user equipment UE (1000), wherein: The network node implementing the H-PCF of the HPLMN is adapted to: providing (508) to the V-PCF HPLMN UE policy subscription data for a subscription permanent identifier SUPI, the HPLMN UE policy subscription data comprising an indication as to whether local offload (LBO) roaming by the UE is allowed for one or more specified combinations of a data network name (DNN) and single network slice selection assistance information (S-NSSAI); The network node implementing the V-PCF of the VPLMN is adapted to: receiving (508) the HPLMN UE policy subscription data for the SUPI from the H-PCF in response to the UE being registered in the VPLMN and a UE policy association being established between the H-PCF of the HPLMN and the V-PCF of the VPLMN; generating (512b) URSP rules for the UE in the VPLMN; determining (512b) based on the HPLMN UE policy subscription data, in one or more routing descriptor (RSD) components in the URSP rule, whether LBO roaming is allowed for a specified DNN or for one or more specified combinations of a DNN and an S-NSSAI; as well as In response to determining that LBO roaming is allowed, sending (518) the URSP rules to the UE; and The UE is adapted to: determining (604) whether the S-NSSAI is contained in a list of allowed S-NSSAIs based on checking the URSP rules generated by the VPLMN received from the V-PCF prior to the URSP rules received from the HPLMN; as well as In response to at least determining that the S-NSSAI is included in the list of allowed S-NSSAIs, it is determined (606) that the RSD component of the VPLMN-generated URSP rule is valid.

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