Per UE grant in VPLMN for MBS

Abstract

The invention relates to per UE grant in a VPLMN for MBS. Various techniques are presented for multiple network functions to enable per user equipment authorization in a visited public land mobile network for multicast / broadcast services. Information about roaming user equipment authorized to use a multicast / broadcast service session may be stored at a multicast broadcast session management function (in a visited public land mobile network of the roaming user equipment). Multicast broadcast session management functionality, session management functionality, and network open functionality participate in techniques for implementing per user equipment authorization using information at least at the multicast broadcast session management functionality. The information may also be stored at a unified data management or a unified data repository. Multiple network functions in the various techniques may perform identification of roaming user equipments that are allowed to use multicast / broadcast service sessions.

Description

Technical Field

[0001] Examples of embodiments herein generally relate to cellular communication systems, and more particularly, to providing multicast MBS (Multicast / Broadcast Service) when a UE (User Equipment) is in a Visited Public Land Mobile Network (VPLMN). Background Art

[0002] Multicast / Broadcast Service (MBS) in cellular networks takes into account both broadcasting and multicasting. A broadcast communication service is to send data to all users in a broadcast service area. At the same time, in a multicast communication service, data is sent to a dedicated set of users (i.e., not all users within the coverage of the multicast service are authorized to receive the data). The MBS multicast service can operate regardless of where the UE (User Equipment, which is a wireless device connected to a cellular network) is in the Public Land Mobile Network, and data is sent at the location where the UE is located with respect to any user in the dedicated authorized set of users. However, so far, the reception of the MBS multicast service has been limited to UEs in the "home" Public Land Mobile Network (HPLMN) of the UE and the services provided by that HPLMN. It is also desirable to enable UEs that roam into a "visited" PLMN (VPLMN) to receive the MBS multicast service provided in that VPLMN.

[0003] For example, the UE starts in the "home" Public Land Mobile Network (HPLMN), which is the network of the user's home operator. The operator's PLMN can be regarded as the core network and the Radio Access Network (RAN) of the entity, and the RAN allows the UE to connect to the core network. Once the user of the UE roams outside the HPLMN and enters another PLMN, that PLMN becomes the "visited" PLMN. MBS should operate seamlessly between the two PLMNs, but problems may occur when the UE roams into the VPLMN and is using multicast MBS. Summary of the Invention

[0004] This section is intended to include examples and is not intended as a limitation.

[0005] In an exemplary embodiment, a method is disclosed, comprising: at an MB-SMF in a VPLMN of a roaming UE, for an MBS session, storing at least one of the following: information about a roaming UE authorized to use the MBS session, or corresponding information about MBS assistance for the MBS session related to the roaming UE; receiving, by the MB-SMF, from an SMF in the VPLMN, a request for context state subscription for the MBS session; and sending, by the MB-SMF, using the stored information and in response to the request, at least one of the following: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including an identifier of a related roaming UE.

[0006] Another exemplary embodiment includes a computer program comprising instructions that, when the computer program is run on a device, are configured to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product comprising a computer-readable medium carrying the instructions for use with the device. Another example is according to the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0007] An exemplary device includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the device to at least perform: at an MB-SMF in a VPLMN of a roaming UE, for an MBS session, storing at least one of the following: information about a roaming UE authorized to use the MBS session, or corresponding information about MBS assistance for the MBS session related to the roaming UE; receiving, by the MB-SMF, from an SMF in the VPLMN, a request for context state subscription for the MBS session; and sending, by the MB-SMF, using the stored information and in response to the request, at least one of the following: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including an identifier of a related roaming UE.

[0008] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to perform at least the following operations: at an MB-SMF in the VPLMN of a roaming UE, for an MBS session, store at least one of the following: information about a roaming UE authorized to use the MBS session, or corresponding information about MBS assistance for the MBS session related to the roaming UE; receive, by the MB-SMF from an SMF in the VPLMN, a request for context state subscription for the MBS session; and send, by the MB-SMF using the stored information and in response to the request, at least one of the following: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including the identifier of the related roaming UE.

[0009] In another exemplary embodiment, a device includes components for performing the following operations: at an MB-SMF in the VPLMN of a roaming UE, for an MBS session, store at least one of the following: information about a roaming UE authorized to use the MBS session, or corresponding information about MBS assistance for the MBS session related to the roaming UE; receive, by the MB-SMF from an SMF in the VPLMN, a request for context state subscription for the MBS session; and send, by the MB-SMF using the stored information and in response to the request, at least one of the following: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including the identifier of the related roaming UE.

[0010] In one exemplary embodiment, a method is disclosed, including: receiving, by an SMF in the VPLMN of a roaming UE, an indication from an AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for information about the MBS session to an MB-SMF in the VPLMN; receiving, by the SMF from the MB-SMF in the VPLMN, at least one of the following: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including the identifier of the related roaming UE; performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session.

[0011] Another exemplary embodiment includes a computer program comprising instructions that, when the computer program is run on a device, are configured to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product comprising a computer-readable medium carrying the instructions contained therein for use with the device. Another example is the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0012] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to at least perform: receiving, by an SMF in a VPLMN of a roaming UE, an indication from an AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for information about the MBS session to an MB-SMF in the VPLMN; receiving, by the SMF from the MB-SMF in the VPLMN, at least one of: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including the identifier of the relevant roaming UE; performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session.

[0013] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to at least perform the following operations: receiving, by an SMF in a VPLMN of a roaming UE, an indication from an AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for information about the MBS session to an MB-SMF in the VPLMN; receiving, by the SMF from the MB-SMF in the VPLMN, at least one of: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including the identifier of the relevant roaming UE; performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session.

[0014] In another exemplary embodiment, a device includes components for performing the following operations: receiving, by an SMF in a VPLMN of a roaming UE, an indication from an AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for information regarding the MBS session to an MB-SMF in the VPLMN; receiving, by the SMF from the MB-SMF in the VPLMN, at least one of the following: one or more identifiers of UEs authorized to access the MBS session, or information regarding MBS assistance for the MBS session including an identifier of the associated roaming UE; performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session.

[0015] In one exemplary embodiment, a method is disclosed that includes: receiving, at a NEF from an AF, a message for creating or modifying an MBS session, the message including an identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, or information regarding MBS assistance for the MBS session associated with the roaming UE; and forwarding, from the NEF, the message to an MB-SMF in a VPLMN of the roaming UE.

[0016] An exemplary embodiment includes a computer program that includes instructions that, when the computer program runs on a device, are used to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product including a computer-readable medium that bears the instructions contained therein for use with the device. Another example is according to the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0017] An exemplary device includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the device to at least perform: receiving, at a NEF from an AF, a message for creating or modifying an MBS session, the message including an identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, or information regarding MBS assistance for the MBS session associated with the roaming UE; and forwarding, from the NEF, the message to an MB-SMF in a VPLMN of the roaming UE.

[0018] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to perform at least the following operations: receive, at a NEF, a message from an AF to create or modify an MBS session, the message including an identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, or MBS assistance information for the MBS session related to the roaming UE; and forward the message from the NEF to an MB-SMF in the VPLMN of the roaming UE.

[0019] In another exemplary embodiment, a device includes components for performing the following operations: receive, at a NEF, a message from an AF to create or modify an MBS session, the message including an identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, or MBS assistance information for the MBS session related to the roaming UE; and forward the message from the NEF to an MB-SMF in the VPLMN of the roaming UE.

[0020] In one exemplary embodiment, a method is disclosed that includes: receiving, at a UDM in the VPLMN of a roaming UE, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: one or more identifiers corresponding to one or more UEs authorized to access the MBS session, and MBS assistance information for the MBS session including an identifier of a related UE; determining, by the UDM, an inbound roaming UE from at least one of the following: the one or more UEs authorized to access the MBS session, and the UE related to the information on MBS assistance; and sending, by the UDM, a request to store information related to the MBS session to an MB-SMF or a UDR, the request including the identifier of the MBS session and at least one of the following: the identifier corresponding to the determined inbound roaming UE authorized to access the MBS session, and MBS assistance information for the MBS session including the identifier of the determined inbound roaming UE.

[0021] An exemplary embodiment includes a computer program that includes instructions that, when the computer program is run on a device, are used to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product including a computer-readable medium that bears the instructions contained therein for use with the device. Another example is the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0022] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to at least perform: receiving, at a UDM in a VPLMN of a roaming UE, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: one or more identifiers corresponding to one or more UEs authorized to access the MBS session, and information about MBS assistance for the MBS session including an identifier of a related UE; determining, by the UDM, an inbound roaming UE from at least one of: the one or more UEs authorized to access the MBS session, and the UE related to the information about MBS assistance; and sending, by the UDM, a request to store information related to the MBS session to an MB-SMF or a UDR, the request including the identifier of the MBS session and at least one of the following: the identifier corresponding to the determined inbound roaming UE authorized to access the MBS session, and information about MBS assistance for the MBS session including the identifier of the determined inbound roaming UE.

[0023] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to perform at least the following operations: receive, at a UDM in the VPLMN of a roaming UE, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: one or more identifiers corresponding to one or more UEs authorized to access the MBS session, and information about MBS assistance for the MBS session including an identifier of a related UE; determine, by the UDM, an inbound roaming UE from at least one of the following: the one or more UEs authorized to access the MBS session, and the UE related to the information about MBS assistance; and send, by the UDM, a request to store information related to the MBS session to an MB-SMF or a UDR, the request including the identifier of the MBS session and at least one of the following: the identifier corresponding to the determined inbound roaming UE authorized to access the MBS session, and information about MBS assistance for the MBS session including the identifier of the determined inbound roaming UE.

[0024] In another exemplary embodiment, a device includes components for performing the following operations: receive, at a UDM in the VPLMN of a roaming UE, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: one or more identifiers corresponding to one or more UEs authorized to access the MBS session, and information about MBS assistance for the MBS session including an identifier of a related UE; determine, by the UDM, an inbound roaming UE from at least one of the following: the one or more UEs authorized to access the MBS session, and the UE related to the information about MBS assistance; and send, by the UDM, a request to store information related to the MBS session to an MB-SMF or a UDR, the request including the identifier of the MBS session and at least one of the following: the identifier corresponding to the determined inbound roaming UE authorized to access the MBS session, and information about MBS assistance for the MBS session including the identifier of the determined inbound roaming UE.

[0025] In an exemplary embodiment, a method is disclosed, comprising: storing, at a UDR in a VPLMN of a roaming UE, an identifier of an MBS session and at least one of the following: one or more identifiers corresponding to one or more roaming UEs authorized to access the MBS session, or information on MBS assistance for the MBS session including an identifier of a relevant roaming UE; receiving, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session, the request including a session ID of the MBS session; and sending, by the UDR using the stored information and in response to the request, at least one of the following to the SMF: the one or more identifiers of the roaming UEs authorized to access the MBS session corresponding to the session ID, and information on MBS assistance for the MBS session including the identifier of the relevant roaming UE.

[0026] An exemplary embodiment includes a computer program comprising instructions which, when the computer program is run on a device, are used to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product comprising a computer-readable medium carrying the instructions for use with the device. Another example is according to the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0027] An exemplary device includes one or more processors and one or more memories storing instructions which, when executed by the one or more processors, cause the device to at least perform: storing, at a UDR in a VPLMN of a roaming UE, an identifier of an MBS session and at least one of the following: one or more identifiers corresponding to one or more roaming UEs authorized to access the MBS session, or information on MBS assistance for the MBS session including an identifier of a relevant roaming UE; receiving, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session, the request including a session ID of the MBS session; and sending, by the UDR using the stored information and in response to the request, at least one of the following to the SMF: the one or more identifiers of the roaming UEs authorized to access the MBS session corresponding to the session ID, and information on MBS assistance for the MBS session including the identifier of the relevant roaming UE.

[0028] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to perform at least the following operations: store, at a UDR in a VPLMN of a roaming UE, an identifier of an MBS session and at least one of the following: one or more identifiers corresponding to one or more roaming UEs authorized to access the MBS session, or information about MBS assistance for the MBS session that includes an identifier of a related roaming UE; receive, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session, the request including a session ID of the MBS session; and send, by the UDR using the stored information and in response to the request, at least one of the following to the SMF: the one or more identifiers of the roaming UEs authorized to access the MBS session corresponding to the session ID, and information about MBS assistance for the MBS session that includes the identifier of the related roaming UE.

[0029] In another exemplary embodiment, a device includes components for performing the following operations: store, at a UDR in a VPLMN of a roaming UE, an identifier of an MBS session and at least one of the following: one or more identifiers corresponding to one or more roaming UEs authorized to access the MBS session, or information about MBS assistance for the MBS session that includes an identifier of a related roaming UE; receive, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session, the request including a session ID of the MBS session; and send, by the UDR using the stored information and in response to the request, at least one of the following to the SMF: the one or more identifiers of the roaming UEs authorized to access the MBS session corresponding to the session ID, and information about MBS assistance for the MBS session that includes the identifier of the related roaming UE.

[0030] In an exemplary embodiment, a method is disclosed, comprising: receiving, by an SMF in a VPLMN of a roaming UE, an indication from an AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for a subscription for information related to the MBS session to a UDR in the VPLMN, the request including a session ID of the MBS session; receiving, by the SMF in response to the request, information including at least one of the following items from the UDR in the VPLMN: one or more identifiers of roaming UEs authorized to access the MBS session corresponding to the session ID, or information about MBS assistance for the MBS session including identifiers of relevant roaming UEs; performing, by the SMF, an authorization check for the roaming UE to see if the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the information for MBS assistance indicating that the UE is authorized to join the MBS session.

[0031] Another exemplary embodiment includes a computer program comprising instructions that, when the computer program is run on a device, are used to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product comprising a computer-readable medium that bears the instructions contained therein for use with the device. Another example is the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0032] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to at least perform: receiving, by an SMF in a VPLMN of a roaming UE, an indication from an AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for a subscription for information related to the MBS session to a UDR in the VPLMN, the request including a session ID of the MBS session; receiving, by the SMF in response to the request, from the UDR in the VPLMN, information including at least one of: one or more identifiers of roaming UEs authorized to access the MBS session corresponding to the session ID, or information about MBS assistance for the MBS session including an identifier of a related roaming UE; performing, by the SMF, an authorization check for the roaming UE to see if the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the information for MBS assistance indicating that the UE is authorized to join the MBS session.

[0033] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to at least perform the following operations: receiving, by an SMF in a VPLMN of a roaming UE, an indication from an AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for a subscription for information related to the MBS session to a UDR in the VPLMN, the request including a session ID of the MBS session; receiving, by the SMF in response to the request, from the UDR in the VPLMN, information including at least one of: one or more identifiers of roaming UEs authorized to access the MBS session corresponding to the session ID, or information about MBS assistance for the MBS session including an identifier of a related roaming UE; performing, by the SMF, an authorization check for the roaming UE to see if the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the information for MBS assistance indicating that the UE is authorized to join the MBS session.

[0034] In another exemplary embodiment, a device includes components for performing the following operations: receiving, by an SMF in a VPLMN of a roaming UE, an indication from an AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for a subscription for information related to the MBS session to a UDR in the VPLMN, the request including a session ID of the MBS session; receiving, by the SMF in response to the request, from the UDR in the VPLMN, information including at least one of the following: one or more identifiers of roaming UEs authorized to access the MBS session corresponding to the session ID, or information about MBS assistance for the MBS session including an identifier of a related roaming UE; performing, by the SMF, an authorization check for the roaming UE to see if the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the information for MBS assistance indicating that the UE is authorized to join the MBS session.

[0035] In one exemplary embodiment, a method is disclosed that includes: at a UDM in an HPLMN of a roaming UE, receiving, from an NEF in the HPLMN or a UDM in a VPLMN, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, information for MBS assistance, the information including a general public subscription identifier of a related roaming UE, a VPLMN ID, and a service class; using, by the UDM, at least one of the following for a separately received general public subscription identifier of a roaming UE to check if the roaming UE is authorized to access the MBS service of the MBS session: the received VPLMN ID, the received service class, the stored information about whether the UE is entitled to receive MBS services when roaming, the stored information about the VPLMN from which the UE is entitled to receive MBS services when roaming, or the stored information about the service class of the MBS services that the UE is entitled to receive when roaming; and storing, by the UDM, for an individual UE among those roaming UEs authorized to receive the MBS service in the VPLMN, at least one of the following: the identifier of the authorized MBS session corresponding to the MBS service, or information about MBS assistance for the MBS session.

[0036] Another exemplary embodiment includes a computer program comprising instructions that, when the computer program is run on a device, are for performing the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product comprising a computer-readable medium carrying the instructions contained therein for use with the device. Another example is the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0037] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to at least perform: at a UDM in the HPLMN of a roaming UE, receiving, from an NEF in the HPLMN or a UDM in the VPLMN, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: a general public subscription identifier of the roaming UE authorized to access the MBS session, information for MBS assistance, the information including a general public subscription identifier of the associated roaming UE, a VPLMN ID, and a service class; using, by the UDM, at least one of the following for a separately received general public subscription identifier of the roaming UE to check whether the roaming UE is authorized to access the MBS service of the MBS session: the received VPLMN ID, the received service class, the stored information on whether the UE is entitled to receive the MBS service when roaming, the stored information on the VPLMN from which the UE is entitled to receive the MBS service when roaming, or the stored information on the service class of the MBS service that the UE is entitled to receive when roaming; and storing, by the UDM, for an individual UE among those roaming UEs authorized to receive the MBS service in the VPLMN, at least one of the following: the identifier of the authorized MBS session corresponding to the MBS service, or the information for MBS assistance for the MBS session.

[0038] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to perform at least the following operations: at a UDM in the HPLMN of a roaming UE, receive, from an NEF in the HPLMN or a UDM in a VPLMN, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: a general public subscription identifier of the roaming UE authorized to access the MBS session, information for MBS assistance, the information including a general public subscription identifier of the associated roaming UE, a VPLMN ID, and a service class; by the UDM, for a separately received general public subscription identifier of the roaming UE, use at least one of the following to check whether the roaming UE is authorized to access an MBS service of the MBS session: the received VPLMN ID, the received service class, the stored information on whether the UE is entitled to receive MBS services when roaming, the stored information on the VPLMN from which the UE is entitled to receive MBS services when roaming, or the stored information on the service class of the MBS services that the UE is entitled to receive when roaming; and by the UDM, for an individual UE among those roaming UEs authorized to receive the MBS service in the VPLMN, store at least one of the following: the identifier of the authorized MBS session corresponding to the MBS service, or information for MBS assistance for the MBS session.

[0039] In another exemplary embodiment, a device includes components for performing the following operations: at a UDM in the HPLMN of a roaming UE, receive, from the NEF in the HPLMN or the UDM in the VPLMN, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, information for MBS assistance, the information including a general public subscription identifier of the associated roaming UE, a VPLMN ID, and a service class; use, by the UDM, for a separately received general public subscription identifier of the roaming UE, at least one of the following to check whether the roaming UE is authorized to access the MBS service of the MBS session: the received VPLMN ID, the received service class, the stored information on whether the UE is entitled to receive the MBS service when roaming, the stored information on the VPLMN from which the UE is entitled to receive the MBS service when roaming, or the stored information on the service class of the MBS service that the UE is entitled to receive when roaming; and store, by the UDM, for an individual UE among those roaming UEs authorized to receive the MBS service in the VPLMN, at least one of the following: the identifier of the authorized MBS session corresponding to the MBS service, or the information for MBS assistance for the MBS session.

[0040] In one exemplary embodiment, a method is disclosed that includes: at an AF in a PLMN that provides data for an MBS session, identify a UE having a different PLMN as its HPLMN that is authorized to participate in the MBS session and the HPLMN of the UE; and send, from the AF to the NEF in the HPLMN, a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a roaming UE from the HPLMN authorized to access the MBS session, information for MBS assistance including a general public subscription identifier of the associated roaming UE from the HPLMN, a PLMN ID of the PLMN that provides the MBS session, and a service class.

[0041] Another exemplary embodiment includes a computer program that includes instructions that, when the computer program runs on a device, are used to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product including a computer-readable medium that bears the instructions contained therein for use with the device. Another example is according to the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0042] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to at least perform: at an AF in a PLMN that provides data for an MBS session, identifying UEs that are authorized to participate in the MBS session and that have a different PLMN as their HPLMN, and the HPLMN of the UEs; and sending, from the AF to a NEF in the HPLMN, a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a roaming UE from the HPLMN that is authorized to access the MBS session, information for MBS assistance including the general public subscription identifier of a related roaming UE from the HPLMN, a PLMN ID of the PLMN that provides the MBS session, and a service class.

[0043] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to at least perform the following operations: at an AF in a PLMN that provides data for an MBS session, identifying UEs that are authorized to participate in the MBS session and that have a different PLMN as their HPLMN, and the HPLMN of the UEs; and sending, from the AF to a NEF in the HPLMN, a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a roaming UE from the HPLMN that is authorized to access the MBS session, information for MBS assistance including the general public subscription identifier of a related roaming UE from the HPLMN, a PLMN ID of the PLMN that provides the MBS session, and a service class.

[0044] In another exemplary embodiment, a device includes components for performing the following operations: at an AF in a PLMN that provides data for an MBS session, identifying UEs that are authorized to participate in the MBS session and that have a different PLMN as their HPLMN, and the HPLMN of the UEs; and sending, from the AF to a NEF in the HPLMN, a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a roaming UE from the HPLMN that is authorized to access the MBS session, information for MBS assistance including the general public subscription identifier of a related roaming UE from the HPLMN, a PLMN ID of the PLMN that provides the MBS session, and a service class.

[0045] In an exemplary embodiment, a method is disclosed, comprising: at a UDM in a PLMN providing an MBS session, receiving, from a NEF in the PLMN, a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, information for MBS assistance including the general public subscription identifier of the associated UE, or a service class; at the UDM, identifying a general public subscription identifier of a UE having a different PLMN as the HPLMN and the HPLMN of the UE; and sending, from the UDM in the PLMN to a UDM in the HPLMN, a request to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE from the HPLMN authorized to access the MBS session, information for MBS assistance including the general public subscription identifier of the associated roaming UE from the HPLMN, a PLMN ID of the PLMN providing the MBS session, or a service class.

[0046] Another exemplary embodiment includes a computer program comprising instructions that, when the computer program is run on a device, are used to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions contained therein for use with the device. Another example is according to the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0047] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to at least perform: at a UDM in a PLMN providing an MBS session, receive from a NEF in the PLMN a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, MBS assistance information including the general public subscription identifier of the associated UE, or a service class; at the UDM, identify a general public subscription identifier of a UE having a different PLMN as its HPLMN and the HPLMN of the UE; and send from the UDM in the PLMN to a UDM in the HPLMN a request to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE from the HPLMN authorized to access the MBS session, MBS assistance information including the general public subscription identifier of the associated roaming UE from the HPLMN, the PLMN ID of the PLMN providing the MBS session, or a service class.

[0048] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to at least perform the following operations: at a UDM in a PLMN providing an MBS session, receive from a NEF in the PLMN a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, MBS assistance information including the general public subscription identifier of the associated UE, or a service class; at the UDM, identify a general public subscription identifier of a UE having a different PLMN as its HPLMN and the HPLMN of the UE; and send from the UDM in the PLMN to a UDM in the HPLMN a request to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE from the HPLMN authorized to access the MBS session, MBS assistance information including the general public subscription identifier of the associated roaming UE from the HPLMN, the PLMN ID of the PLMN providing the MBS session, or a service class.

[0049] In another exemplary embodiment, a device includes components for performing the following operations: at a UDM in a PLMN providing an MBS session, receive a request to provide data for the MBS session from a NEF in the PLMN, the request including at least one of the following items: an identifier of the MBS session, and at least one of the following items: a general public subscription identifier of a UE authorized to access the MBS session, MBS assistance information including the general public subscription identifier of the associated UE, or a service class; at the UDM, identify a general public subscription identifier of a UE having a different PLMN as the HPLMN and the HPLMN of the UE; and send a request to provide data for the MBS session from the UDM in the PLMN to a UDM in the HPLMN, the request including the identifier of the MBS session and at least one of the following items: a general public subscription identifier of a roaming UE from the HPLMN authorized to access the MBS session, MBS assistance information including the general public subscription identifier of the associated roaming UE from the HPLMN, a PLMN ID of the PLMN providing the MBS session, or a service class.

[0050] In an exemplary embodiment, a method is disclosed, comprising: at a UDM in a PLMN providing an MBS session, receiving, from a NEF in the PLMN, a request to provide data for the MBS session, the request including at least one of the following items: an identifier of the MBS session, and at least one of the following items: a general public subscription identifier of a UE authorized to access the MBS session, or information for MBS assistance including the general public subscription identifier of the associated UE; at the UDM, identifying a general public subscription identifier of a UE having a different PLMN as its HPLMN and the HPLMN of the UE; for each separately identified UE, sending, from the UDM in the PLMN to the UDM in the HPLMN of the identified UE, a request to provide an identifier of an SMF for processing the identified UE, the request including the general public subscription identifier of the identified UE; for each separately identified UE, receiving, at the UDM in the PLMN, from the UDM in the HPLMN of the identified UE, a response including at least one identifier of an SMF for processing the identified UE and a subscription permanent identifier of the identified UE; and for each separately identified UE, sending, from the UDM in the PLMN to the SMF, a request to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following items: the subscription permanent identifier of the identified roaming UE indicating that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance including the subscription permanent identifier of the identified roaming UE.

[0051] Another exemplary embodiment includes a computer program comprising instructions that, when the computer program is run on a device, are used to perform the method described in the previous paragraph. According to the computer program described in that paragraph, wherein the computer program is a computer program product comprising a computer-readable medium carrying the instructions contained therein for use with the device. Another example is according to the computer program described in that paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0052] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to at least perform: at a UDM in a PLMN providing an MBS session, receive, from a NEF in the PLMN, a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, or information for MBS assistance including the general public subscription identifier of a related UE; at the UDM, identify the general public subscription identifier of a UE having a different PLMN as its HPLMN and the HPLMN of the UE; for each separately identified UE, send, from the UDM in the PLMN, a request to the UDM in the HPLMN of the identified UE to provide an identifier of an SMF for processing the identified UE, the request including the general public subscription identifier of the identified UE; for each separately identified UE, receive, at the UDM in the PLMN, a response from the UDM in the HPLMN of the identified UE, the response including at least one identifier of an SMF for processing the identified UE and a subscription permanent identifier of the identified UE; and for each separately identified UE, send, from the UDM in the PLMN, a request to the SMF to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following: the subscription permanent identifier of the identified roaming UE indicating that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance including the subscription permanent identifier of the identified roaming UE.

[0053] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to perform at least the following operations: at a UDM in a PLMN providing an MBS session, receive, from a NEF in the PLMN, a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, or information for MBS assistance including the general public subscription identifier of the associated UE; at the UDM, identify the general public subscription identifier of a UE having a different PLMN as the HPLMN and the HPLMN of the UE; for each separately identified UE, send, from the UDM in the PLMN to the UDM in the HPLMN of the identified UE, a request to provide an identifier of an SMF that processes the identified UE, the request including the general public subscription identifier of the identified UE; for each separately identified UE, receive, at the UDM in the PLMN, from the UDM in the HPLMN of the identified UE, a response including at least one identifier of an SMF that processes the identified UE and a subscription permanent identifier of the identified UE; and for each separately identified UE, send, from the UDM in the PLMN to the SMF, a request to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following: the subscription permanent identifier of the identified roaming UE indicating that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance including the subscription permanent identifier of the identified roaming UE.

[0054] In another exemplary embodiment, a device comprises components for performing the following operations: at a UDM in a PLMN providing an MBS session, receiving, from a NEF in the PLMN, a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, or information for MBS assistance including the general public subscription identifier of a related UE; at the UDM, identifying a general public subscription identifier of a UE having a different PLMN as its HPLMN and the HPLMN of the UE; for each separately identified UE, sending, from the UDM in the PLMN to a UDM in the HPLMN of the identified UE, a request to provide an identifier of an SMF for processing the identified UE, the request including the general public subscription identifier of the identified UE; for each separately identified UE, receiving, at the UDM in the PLMN, from the UDM in the HPLMN of the identified UE, a response including at least one identifier of an SMF for processing the identified UE and a subscription permanent identifier of the identified UE; and for each separately identified UE, sending, from the UDM in the PLMN to the SMF, a request to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following: the subscription permanent identifier of the identified roaming UE indicating that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance including the subscription permanent identifier of the identified roaming UE.

[0055] In an exemplary embodiment, a method is disclosed, comprising: receiving, by an SMF in a VPLMN of a roaming UE, from a UDM in the VPLMN, a request for providing data for an MBS session, the request including an identifier of the MBS session and at least one of the following: a subscription permanent identifier of the roaming UE for indicating that the roaming UE is authorized to access the MBS session, and information for MBS assistance including the subscription permanent identifier of the roaming UE; storing, by the SMF, the received identifier of the MBS session and at least one of the following: the received subscription permanent identifier of the roaming UE for indicating that the roaming UE is authorized to access the MBS session, or the received information for MBS assistance including the subscription permanent identifier of the roaming UE; receiving, by the SMF, from an AMF in the VPLMN, an indication that the roaming UE wants to join the MBS session; performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and sending, by the SMF, to the AMF, a response to the indication that the roaming UE wants to join the MBS session, the response indicating that the UE is authorized to join the MBS session.

[0056] Another exemplary embodiment includes a computer program, the computer program including instructions that, when the computer program runs on a device, are used to execute the method described in the previous paragraph. According to the computer program described in this paragraph, wherein the computer program is a computer program product including a computer-readable medium, the computer-readable medium carrying the instructions contained therein for use with the device. Another example is according to the computer program described in this paragraph, wherein the program can be directly loaded into the internal memory of the device.

[0057] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to at least perform: receiving, by an SMF in a VPLMN of a roaming UE, from a UDM in the VPLMN, a request for providing data for an MBS session, the request including an identifier of the MBS session and at least one of the following: a subscription permanent identifier of the roaming UE for indicating that the roaming UE is authorized to access the MBS session, and MBS assistance information including the subscription permanent identifier of the roaming UE; storing, by the SMF, the received identifier of the MBS session and at least one of the following: the received subscription permanent identifier of the roaming UE for indicating that the roaming UE is authorized to access the MBS session, or the received MBS assistance information including the subscription permanent identifier of the roaming UE; receiving, by the SMF, from an AMF in the VPLMN, an indication that the roaming UE wants to join the MBS session; performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session.

[0058] An exemplary computer program product includes a computer-readable storage medium carrying instructions that, when executed by a device, cause the device to at least perform the following operations: receiving, by an SMF in a VPLMN of a roaming UE, from a UDM in the VPLMN, a request for providing data for an MBS session, the request including an identifier of the MBS session and at least one of the following: a subscription permanent identifier of the roaming UE for indicating that the roaming UE is authorized to access the MBS session, and MBS assistance information including the subscription permanent identifier of the roaming UE; storing, by the SMF, the received identifier of the MBS session and at least one of the following: the received subscription permanent identifier of the roaming UE for indicating that the roaming UE is authorized to access the MBS session, or the received MBS assistance information including the subscription permanent identifier of the roaming UE; receiving, by the SMF, from an AMF in the VPLMN, an indication that the roaming UE wants to join the MBS session; performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session.

[0059] In another exemplary embodiment, a device includes components for performing the following operations: receiving, by an SMF in a VPLMN of a roaming UE, from a UDM in the VPLMN, a request for providing data for an MBS session, the request including an identifier of the MBS session and at least one of the following: a subscription permanent identifier of the roaming UE indicating that the roaming UE is authorized to access the MBS session, and information for MBS assistance including the subscription permanent identifier of the roaming UE; storing, by the SMF, the received identifier of the MBS session and at least one of the following: the received subscription permanent identifier of the roaming UE indicating that the roaming UE is authorized to access the MBS session, or the received information for MBS assistance including the subscription permanent identifier of the roaming UE; receiving, by the SMF, from an AMF in the VPLMN, an indication that the roaming UE wants to join the MBS session; performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In the drawings:

[0061] Figure 1 is a block diagram of a system including a VPLMN and an HPLMN connected together through an interface, and is an example of a system that can be used to implement the exemplary embodiments herein;

[0062] Figure 1A is a block diagram of one possible non - restrictive exemplary system in which the exemplary embodiments can be practiced;

[0063] Figure 2 is an example of a signaling diagram showing a first technique (Technique 1) and a first embodiment (Embodiment 1) of the technique;

[0064] Figure 3 is an example of a signaling diagram showing a first technique (Technique 1) and a second embodiment (Embodiment 2) of the technique;

[0065] Figure 4 is an example of a signaling diagram showing a second technique (Technique 2);

[0066] Figure 4A is to help explain Figure 3 and 4 some of the operations and signaling in the flowchart;

[0067] Figure 5 is an example of a signaling diagram showing a third technique (Technique 3) and a first embodiment (Embodiment 1) of the technique;

[0068] Figure 6 is an example of a signaling diagram showing a third technology (Technology 3) and a second embodiment (Embodiment 2) of the technology;

[0069] Figure 6A is to help explain for Figure 5 and 6 the flowchart of the check for the roaming UE in;

[0070] Figure 7 is an example of a signaling diagram showing a fourth technology (Technology 4);

[0071] Figure 8 、 9 and 10 are flowcharts respectively showing the corresponding parts of Technology 1 at the MB-SMF, SMF, and NEF;

[0072] Figure 11 is applied to Figure 3 and 4 the flowchart of the operation of the UDM;

[0073] Figure 12 is at least applied to Figure 4 the flowchart of the operation of the UDR;

[0074] Figure 13 is at least applied to Figure 4 the flowchart of the operation of the SMF;

[0075] Figure 14 is at least applied to Figure 5 and 6 the flowchart of the operation of the UDM;

[0076] Figure 15 is at least applied to Figure 5 the flowchart of the operation of the AF;

[0077] Figure 16 is at least applied to Figure 5 the flowchart of the operation of the UDM;

[0078] Figure 17 is at least applied to Figure 5 the flowchart of the operation of the UDM; and

[0079] Figure 18 is at least applied to Figure 7 the flowchart of the operation of the SMF. Detailed Description of the Invention

[0080] Abbreviations that may appear in this specification and / or the drawings are defined at the end of the following "Detailed Description of the Invention" section.

[0081] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. All embodiments described in this "Detailed Description" are exemplary embodiments intended to enable persons skilled in the art to make or use the invention, rather than to limit the scope of the invention which is defined by the claims.

[0082] When more than one drawing reference number, word or acronym is used with “ / ” within this specification, and generally as used within this specification, “ / ” may be interpreted as “or”, “and” or “both”. As used herein, “at least one of the following: ” and “at least one of ” and similar expressions (wherein a list of two or more elements is connected by “and” or “or”) mean at least any one element, or at least any two or more elements, or at least all elements.

[0083] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when used herein, the terms "comprising", "having", "including" specify the presence of stated features, elements and / or components, etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0084] Any flowchart or signaling diagram in this document ( Figure 2-7 4A) are to be viewed as logical flow diagrams and illustrate the operation of an exemplary method, the result of execution of computer program instructions embodied on a computer readable memory, the functions performed by hardware implemented logic, and / or the interconnected components for performing functions according to the exemplary embodiments. Block diagrams (e.g. Figure 1 and Figure 1A ) also illustrate the operation of an exemplary method, the result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and / or interconnected components for performing functions according to exemplary embodiments. For methods, flow charts, and signaling diagrams, the order of method steps, blocks in a flow, or signaling is not important but is an example.

[0085] Before continuing with the examples of the embodiments, the technical fields related to the embodiments are introduced. One such field is 5G.

[0086] The enhancement of 5G systems to support Multicast and Broadcast Communication Services (MBS) using NR has been standardized by 3GPP in 3GPP TS 23.247 (see for example 3GPP TS 23.247 V18.3.0 (September 2023) Architectural enhancements for 5G multicast-broadcast services, Stage 2). An MBS multicast session can be open to "any UE" entitled to use the MBS multicast service, or only to specific UEs provided by the AF that also creates the MBS multicast session.

[0087] Despite the Phase 1 requirements related to roaming, roaming is not yet supported for MBS: This is illustrated by the following text in 3GPP TS 22.246:

[0088]

[0089] According to the existing standards, both the MBS session authorization information and the MBS session assistance information are provided by the AF to the NEF via the NEF parameter provisioning procedure and stored by the NEF in the UDM. The specific relevant parts of the 3GPP specifications are outlined below.

[0090] In 3GPP TS 23.247 (see for example 3GPP TS 23.247 Architecture enhancements for 5G System (5GS) to support network data analytics services), this states the following:

[0091]

[0092] This is further described by Table 6.4.2-1: MBS Subscription Data Types shown below:

[0093]

[0094] Table 6.4.2-2 describes the MBS subscription data type keys and is shown below:

[0095] Subscription data type Data key Data sub-key MBS subscription data SUPI -

[0096] Another relevant section is as follows:

[0097]

[0098] The above section relates to Table 6.4.3-1 MBS data type keys shown below:

[0099] Data set Data subset Data key Data sub-key Subscription data MBS subscription data SUPI -

[0100] Another related section is as follows:

[0101]

[0102] The following table is relevant, Table 7.2.9-1: MBS session authorization information:

[0103]

[0104] 7.2.9-2: Multicast MBS group member management parameters is shown below:

[0105] Parameter Description List of GPSIs List of multicast group members, each member identified by a GPSI. External group ID Identifier of the multicast MBS group.

[0106] Another related section is as follows:

[0107]

[0108] Table 7.2.9a-1: MBS session assistance information is shown below:

[0109]

[0110] 3GPP TS23.288 also describes the following:

[0111]

[0112] Another related topic relates to 3GPP TS23.502 (see, for example, 3GPP TS23.502 V18.3.0 (September 2023) Procedures for the 5G System (5GS), Stage 2 (Procedures for the 5G System (5GS), Stage 2, Version 18)). In Figure 4 .15.6.2, the NEF service operation information flow is described.

[0113] In 3GPP TS23.247, the signaling diagram is described in 7.1.1.2 MBS Session Creation without PCC. The steps in the diagram are also described. A part of Section 7.2.1.2 is repeated below:

[0114]

[0115] Section 7.2.1.3 describes the multicast session join and session establishment procedures via at least the signaling diagram and the corresponding text.

[0116] Some unsolved problems include the following items.

[0117] 1. Access to MBS multicast services may be restricted to a UE or a group of UEs. The UE obtains the permission to use such an MBS service by interacting with the AF that creates the MBS service in the PLMN, and the AF provides information about the authorized users to the PLMN. This information is stored in the UDM of the PLMN per UE. However, for roaming users, the UDM is located in the HPLMN, and it may not be desirable to store information about services provided locally in the VPLMN in the HPLMN. Otherwise, techniques on how to store the information in the UDM of the HPLMN would be required.

[0118] 2. In Rel-18 MBS, auxiliary information is introduced. The MBS auxiliary information for an MBS session is an indication that some UEs are preferably kept in RRC_Connected when the relevant MBS session activity that the UE joins. The MBS auxiliary information is also provided by the AF that creates the MBS session and is stored in the UDM per UE.

[0119] Generally, the examples in this document may focus on additional authorization for roaming users to use specific MBS services that are only open to UEs selected by the AF. Additionally, the examples may also address the AF providing MBS auxiliary information for an MBS session for roaming users. As background, the MBS auxiliary information for an MBS session is an optional parameter introduced in Rel-18 multicast and is associated with an MBS session, which includes an indication that the UE is preferably kept in RRC_Connected when the relevant MBS session activity that the UE joins - note that Rel-18 multicast also introduces UEs in RRC_INACTIVE to be able to receive multicast services.

[0120] Examples for solving the above problems are described below.

[0121] Regarding problem (1), the embodiments in this document solve how to enable an inbound roaming UE to access MBS services provided locally in the VPLMN that are only open to specific UEs (e.g., MBS services created by an AF that interacts with the VPLMN, and the AF also provides information about authorized users to the VPLMN). An inbound roaming UE is a roaming UE that enters the VPLMN.

[0122] Regarding problem (2), the examples also solve how to provide and store the MBS auxiliary information for roaming users to receive MBS services provided in the VPLMN.

[0123] An overview of specific examples is provided now, and more details are provided below. As an overview, four alternative techniques for solving or overcoming at least the above problems are as follows.

[0124] Technique 1: The MB-SMF stores information about roaming UEs entitled to use an MBS session and / or MBS assistance information of a roaming user. In one embodiment, the AF identifies the roaming user and provides the MB-SMF with information about roaming UEs entitled to use the corresponding MBS session and / or MBS assistance information of the roaming user, for example as part of the MBS session creation or modification process. In another embodiment, the AF uses an existing parameter provisioning procedure for the UDM in the VPLMN, and the UDM identifies the roaming user and provides the MB-SMF handling the MBS session with information about roaming UEs entitled to use the MBS session and / or MBS assistance information of the roaming user.

[0125] Technique 2: Use a database (such as the UDR) in the VPLMN to store information about roaming UEs entitled to use an MBS session and / or MBS assistance information of the roaming user.

[0126] Technique 3: The UDM in the HPLMN stores information about roaming UEs entitled to use an MBS session and / or MBS assistance information of the roaming user. In one embodiment, the AF identifies the roaming user and provides the UDM in the HPLMN with information about roaming UEs entitled to use the MBS session and / or MBS assistance information of the roaming user. In another embodiment, the AF uses an existing parameter provisioning procedure for the UDM in the VPLMN, and the UDM identifies the roaming user and provides the UDM in the HPLMN with information about roaming UEs entitled to use the MBS session and / or MBS assistance information of the roaming user.

[0127] Technique 4: The SMF stores information about roaming UEs entitled to use an MBS session and / or MBS assistance information of the roaming user.

[0128] Reference Figure 1, this figure is a block diagram of a system including a VPLMN and an HPLMN connected together through an interface, and is an example of a system that can be used to implement the exemplary embodiments herein. In this figure and other figures, "V" is used to indicate the VPLMN, and "H" is used to indicate the HPLMN. A (roaming) UE 10 can contact the NG-RAN, which, for example, is a base station providing access to the core network in the VPLMN 110. The connection between the UE 10 and the AMF 99-1V is also shown, although this connection goes through the NG-RAN 70. The reference numeral 99 is used to indicate functions in the core network. The core network 90V of the VPLMN 110 includes the following: AMF 99-1V; SMF 99-2V; MB-SMF 99-3V; NEF 99-4V; UDM 99-5V; and UDR 99-6V. The core network 90H of the HPLMN 120 includes the following: NEF 99-4V and UDM 99-5H. The AF 80 is generally outside the core networks 90V and 90H.

[0129] Go to Figure 1A , this figure shows a block diagram of a possible non-limiting example of a cellular network 1 connected to a user equipment (UE) 10. In Figure 1A the cellular network, multiple network elements are shown: the base station 70; and the core network 90. The core network 90 can be the core network 90V of the VPLMN or the core network 90H of the HPLMN.

[0130] In Figure 1A , the user equipment (UE) 10 communicates wirelessly with the base station 70 of the cellular network 1 via a radio link 11. The UE 10 is a wireless communication device configured to access the cellular network, such as a mobile device. The UE 10 is shown to have one or more antennas 28. The ellipsis 2 indicates that there may be multiple UEs 10 communicating wirelessly with the base station 70 via the radio link. The UE 10 includes one or more processors 13, one or more memories 15, and other circuitry 16. The other circuitry 16 includes one or more receivers (Rx) 17 and one or more transmitters (Tx) 18. The program 12 is used to cause the UE 10 to perform the operations described herein. For the UE 10, the other circuitry 16 may include, for example, circuitry for a user interface unit (not shown) such as a display.

[0131] Base station 70 (as a network element of cellular network 1) provides UE 10 with access to cellular network 1 and data network 91 via core network 90 (e.g., via the user plane function (UPF) of core network 90). Thus, base station 70 can be regarded as an access node that provides UE 10 with access to cellular network 1. Base station 70 is shown as having one or more antennas 58. Generally speaking, base station 70 can be called RAN node 70, although many people alternatively call it gNB (gNode B, the base station of NR (New Radio)). However, there are many other examples of RAN nodes, including eNB (evolved Node B) or TRP (Transmission and Reception Point). Base station 70 includes one or more processors 73, one or more memories 75, and other circuitry 76. Other circuitry 76 includes one or more receivers (Rx) 77 and one or more transmitters (Tx) 78. Program 72 is used to cause base station 70 to perform the operations described herein.

[0132] Note that base station 70 can alternatively be implemented via other wireless technologies, such as Wi-Fi (a wireless networking protocol used for devices to communicate without a direct cable connection). In the case of Wi-Fi, link 11 can be characterized as a wireless link.

[0133] Two or more base stations 70 communicate using, for example, link 79. Link 79 can be a wired link, a wireless link, or both, and can implement, for example, the Xn interface for 5G (Fifth Generation), the X2 interface for LTE (Long Term Evolution), or other suitable interfaces for other standards.

[0134] Cellular network 1 can include core network 90 (e.g., 90H or 90V), as one or more second network elements, which can include core network functions and provide a connection to data network 91 (such as a telephone network and / or a data communication network (such as the Internet)) via one or more links 81. Core network 90 includes one or more processors 93, one or more memories 95, and other circuitry 96. Other circuitry 96 includes one or more receivers (Rx) 97 and one or more transmitters (Tx) 98. Program 92 is used to cause core network 90 to perform the operations described herein.

[0135] The core network 90 may be a 5GC (5G core network). The core network 90 may implement or include multiple network functions (NFs) 99, and the procedure 92 may include one or more NFs 99. The 5G core network may use hardware such as memory and processors, as well as a virtualization layer. It may be a single stand-alone computing system, a distributed computing system, or a cloud computing system. The NFs 99 of the core network (as network units) may be containers or virtual machines running on the hardware of the computing system including the core network 90.

[0136] The core network functions of 5G may include: an access and mobility management function provided by the network function 99, such as an access and mobility management function (AMF 99-1); a session management function provided by the network function, such as a session management function (SMF 99-2); a session management function for MBS (MB-SMF 99-3); a network exposure function between the network infrastructure and external entities (NEF 99-4); a network management function for user data in a single centralized unified data management unit (UDM 99-5); and / or a storage function for storing user data in a unified data repository (UDR 99-6). The core network functions for access and mobility management in an LTE (Long-Term Evolution) network may be provided by an MME (Mobility Management Entity) and / or an SGW (Serving Gateway) function (which routes data to a data network). Many other functions are possible, as shown by the examples in Figure 1A : AMF; SMF; MME; SGW; GMLC (Gateway Mobile Location Center); LMF (Location Management Function); UDM (Unified Data Management) / UDR (Unified Data Repository); NRF (Network Repository Function); and / or E-SMLC (Evolved Serving Mobile Location Center). These are only exemplary core network functions that may be provided by the core network 90, and note that both 5G and LTE core network functions may be provided by the core network 90. The base station 70 is coupled to the core network 90 via a backhaul link 31. The base station 70 and the core network 90 may include an NG (Next Generation) interface for 5G, or an S1 interface for LTE, or other suitable interfaces for other radio access technologies to communicate via the backhaul link 31.

[0137] Note that Clause 6 of 3GPP TS23.501 V18.3.0 (September 2023) "provides the functional descriptions of network functions and network entities and the principles for network function and network function service discovery and selection." It provides the descriptions of the following items: AMF 99-1; SMF 99-2; NEF 99-4; UDM 99-5; and UDR 99-6. MB-SMF 99-3 has a similar description in 3GPP TS23.247 V18.3.0 (September 2023) (e.g., §5.3.2.2).

[0138] In data network 91, there is a computer-readable medium 94. The computer-readable medium 94 contains instructions that, when downloaded and installed in the memories 15, 75, or 95 of the corresponding UE 10, base station 70, and / or core network unit 90 and executed by the processors 13, 73, or 93, cause the corresponding devices to perform the corresponding actions described herein. The computer-readable medium 94 can be implemented in other forms (e.g., via an optical disc or a memory stick).

[0139] Programs 12, 72, and 92 contain instructions stored by the corresponding one or more memories 15, 75, or 95. These instructions, when executed by the corresponding one or more processors 13, 73, or 93, cause the corresponding devices 10, 70, or 90 to perform the operations described herein. The computer-readable memories 15, 75, or 95 are circuits and can be of any type suitable for the local technical environment and can be implemented using any suitable data storage technology (e.g., semiconductor-based storage devices, flash memory, firmware, magnetic storage devices and systems, optical storage devices and systems, fixed memory, and removable memory). The computer-readable memories 15, 75, and 95 can be components for performing storage functions. The processors 13, 73, and 93 are circuits and can be of any type suitable for the local technical environment. For example, by way of non-limiting example, these processors can include one or more of the following: general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), processors based on multi-core processor architectures, and can also include special circuits such as field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), signal processing devices, and other devices, or combinations of these devices. The processors 13, 73, and 93 can be components for causing their corresponding devices to perform functions (e.g., the functions described herein).

[0140] Receivers 17, 77, and 97 and transmitters 18, 78, and 98 can implement wired or wireless interfaces. The receivers and transmitters can be grouped together as transceivers.

[0141] The cellular network 1 can implement network virtualization, which is the process of combining hardware and software network resources and network functions into a single software-based management entity (virtual network). Network virtualization involves platform virtualization and is usually combined with resource virtualization. Network virtualization is classified as: external network virtualization, which combines many networks or parts of networks into virtual units; or internal network virtualization, which provides network-like functions to software containers on a single system. Note that the virtualized entities (such as network function 99) generated by network virtualization still use hardware such as processors 73 and / or 93 and memories 75 and / or 95 to some extent, and such virtualized entities also produce technical effects.

[0142] An overview has been provided and more details will be provided. These details are at least partially separate according to the technology provided above.

[0143] One assumption used in this article is that the UE can obtain the permission to use the MBS service via interaction with the AF. In addition, the AF that provides MBS data only has a business relationship with the VPLMN, that is, it has no business relationship with the HPLMN.

[0144] In addition, regarding the "authorized UE" (or authorized user), the MBS assistance information can indicate that specific UEs (not all UEs authorized to access the MBS session) in the MBS session should remain in the RRC connected state so that they can talk immediately in a group call. This can also be applied without explicit UE authorization. 3GPP TS23.247 defines the MBS assistance information as follows:

[0145] "6.17 Support for multicast MBS session data reception in UEs with RRC_INACTIVE state

[0146] In order to provide multicast MBS sessions to more UEs in a cell, if the UE can receive MBS data in the RRC_INACTIVE state, the NG-RAN can decide to move some of the UEs receiving multicast MBS data from RRC_CONNECTED to RRC_INACTIVE state.

[0147] The decision in the NG-RAN can use the following information provided by the 5GC:

[0148] - MBS assistance information for an MBS session. The MBS assistance information for an MBS session is an optional parameter and is associated with an MBS session. It includes an indication that the UE preferably remains connected when the UE joins the relevant MBS session activities. When the NG-RAN node receives this information, even if it supports receiving MBS session data in the RRC_INACTIVE state, the NG-RAN can determine to keep the UE in the RRC_CONNECTED state.

[0149] …

[0150] According to the MBS sessions that the UE joins, if the MBS assistance information is available in the SMF and the MBS sessions that the UE joins are included in the MBS assistance information, the relevant "MBS assistance information for an MBS session" is provided by the SMF to the NG-RAN. The SMF obtains the "MBS assistance information" from the UDM. The MBS assistance information is provided by the AF to the UDM via the NEF as part of the MBS subscription data and includes all MBS session IDs, where the UE preferably remains connected when the UE joins the relevant MBS session activities (as specified in Clause 6.4). During the process where the associated PDU session information needs to be sent to the NG-RAN node (e.g., for PDU session modification for the UE to join, handover process), the SMF provides the "MBS assistance information for an MBS session" in the N2 SM information to the NG-RAN as part of the associated PDU session information.

[0151] One aspect of the embodiments in this document is how to make the provision of assistance information suitable for inbound roaming UEs and MBS sessions in the visited PLMN. Note that MBS assistance information is generally only applicable to some UEs that join multicast sessions, rather than all UEs.

[0152] Authorization is described in 3GPP TS23.247 as follows:

[0153] "6.1.2 UE authorization for services used for multicast

[0154] The following authorizations are defined:

[0155] a) Whether the UE is authorized to use multicast services in the PLMN.

[0156] b) Authorization for the UE to receive the content of a specific multicast MBS session.

[0157] The multicast MBS session can be 'open to any UE'.

[0158] Note 1: … When the UE is configured for a specific multicast MBS session, for example, via a service announcement for a public safety use case, the UE authorization for the specific multicast MBS session can be implicitly performed.

[0159] Note 2: … Even if the authorization according to b) is available, the authorization mentioned in a) is required. If a UE is not authorized by a PLMN to use multicast services, the UE is not authorized to join any multicast MBS session even if the multicast MBS session is 'open to any UE'.

[0160] For a multicast MBS session, the 5GC needs to authorize the UE based on the MBS subscription data and whether the multicast MBS session is 'open to any UE' (which are pre-configured or provided by the AF (see clause 7.2.9)).

[0161] The UE authorization procedure is part of the UE joining procedure and is described in clause 7.2.1.3.

[0162] The authorization part of the example in this document relates to 6.1.2(b) above, and the term 'authorize the UE' can be considered relevant in this context. However, since a multicast MBS session can be 'open to any UE', this indicates that the MBS session can also be open to any UE (and MBS assistance information can still be provided to indicate some UEs within the MBS session). Therefore, the authorization information and the MBS assistance information serve completely different and independent purposes, although both are UE lists related to the MBS session. Both are used in this document because the way of providing this information is almost the same, and similar enhancements can be applied to inbound roaming UEs and MBS sessions in the visited PLMN.

[0163] Figure 2 is an example of a signaling diagram showing a first technology (Technology 1) and a first embodiment (Embodiment 1) of this technology. In Technology 1, the MB-SMF 99-3V stores information about roaming UEs 10 authorized to use the MBS session and / or MBS assistance information of roaming users. Figure 2 Embodiment 1 is also described. In Embodiment 1, the AF 80 connected to the VPLMN 110 identifies the roaming user, for example, via the MCC / MNC part of the GPSI, and when creating an MBS multicast session via the NEF, indicates to the MB-SMF 99-3V the roaming user authorized to use the MBS multicast session and / or the MBS assistance information of the roaming user.

[0164] More specifically, in Figure 2In this scenario, the roaming UE 10 is (at least) connected to the NG-RAN 70, and the NG-RAN 70, AMF 99-1V, SMF 99-2V, and MB-SMF 99-3V are in the VPLMN 110, while at least the UDM 99-5H is in the HPLMN 120. The NEF 99-4 and AF 80 are also shown. In signaling 202, there is a service announcement for the UE to request access to the MBS multicast service. In response, in block 204, the AF 80 identifies the roaming UE 10. The signaling 206 from the AF 80 to the NEF 99-4 includes an Nnef_SMBSession_CreateRequest (or Nnef_SMBSession_ModifyRequest) message that has parameters such as the MBS session ID, the GPSI of the roaming UE authorized to access the MBS service, and MBS assistance information (such as the GPSI of the roaming UE). In signaling 208, the NEF 99-4 forwards this message to the MB-SMF 99-3V.

[0165] The signaling 210, 212, and block 214 are optional. In signaling 210, the MB-SMF sends a Nudm_Identity_Map request (GPSI) message to the UDM 99-5H in the HPLMN 120. The UDM 99-5H responds with a Nudm_Identity_Map response (SUPI) in signaling 212. In block 214, the MB-SMF 99-3V stores the SUPI of the roaming UE authorized to access the MBS service and MBS assistance information (such as the SUPI of the roaming UE).

[0166] The signaling 216 involves the roaming UE 10 sending an UL NAS message (N1 SM container (PDU session modification request (join MBS session request))) to the AMF 99-1V. In signaling 218, the AMF 99-1V sends a Nsmf_PDUSession_UpdateSMContext request message to the SMF 99-2V.

[0167] Signaling 220, 222, and block 224 are optional. In signaling 220, SMF 99-2V sends an Nmbsmf_MBSSession_ContextStatusSubscribe request message to MB-SMF 99-3V. MB-SMF 99-3V responds with an Nmbsmf_MBSSession_ContextStatusSubscribe response (SUPI of the roaming UE authorized to access the MBS service, MBS assistance information (SUPI of the roaming UE)). In block 224, SMG 99-2V performs an authorization check. Note that the terms "authorization" and "authentication" are considered the same in this context. In signaling 226, SMF 99-2V sends an Nsmf_PDUSession_UpdateSMContext response (MBS assistance information) to AMF 99-1V. In block 228, step 6ff in 3GPP TS23.247 Figure 7 .2.1.3-1 is performed. In this context, "ff" refers to step 6 and subsequent steps, such as from step 6 to subsequent steps.

[0168] For Example 2, the following are example steps. In Figure 3 these steps are shown, Figure 3 which is an example of a signaling diagram showing a first technique (Technique 1) and a second embodiment (Example 2) of this technique. Figure 2 Many of the signaling and blocks in Figure 3 are similar to the signaling and blocks in

[0169] 1A. The AF provides the GPSI of the UE authorized to use the MBS session and / or the MBS assistance information for the roaming user to the UDM in the VPLMN via the NEF through a parameter provisioning procedure. See signaling 302, where AF 80 sends an Nnef_MBSSession_Create request () to NEF 99-4. NEF 99-4 sends an Nmbsmf_MBSSession_Create request () to MB-SMF 99-3V in signaling 304. Signaling 202 is performed. Using an Nnef_ParameterProvision_Create request message (MBS session ID, GPSI of the UE authorized to access the MBS service, MBS assistance information (GPSI)), signaling 306 is performed from AF 80 to NEF 99-4. In signaling 308, NEF forwards this request message to UDM 99-5V in VPLMN 110.

[0170] 1B. The UDM 99-5V in the VPLMN identifies roaming users via the MCC / MNC part of the GPSI or via the lack of a UDM entry. If there is no UDM entry for the UE, it is assumed that the UE is roaming. See box 310.

[0171] 1C. The UDM 99-5V in the VPLMN discovers the MB-SMF that processes the MBS multicast session via the NRF, and indicates to the MB-SMF the roaming users authorized to use the MBS multicast session and / or the MBS assistance information for the roaming users. For example, see the signaling 312 of the Nmbsmf_ParameterProvision_Create request (MBS session ID, GPSI of the roaming UE authorized to access the MBS service, MBS assistance information (GPSI) of the roaming UE). More details of 1C can be found in 3GPP TS 23.247 and 3GPP TS23.501.

[0172] 2. When the SMF requests information about the MBS session, the MB-SMF 99-3V passes the information about the roaming users authorized to join the MBS session and / or the MBS assistance information of the roaming users to the SMF. See signaling 220 and 222.

[0173] 3. The SMF uses this information to authenticate the roaming users attempting to join the MBS session and / or provide assistance information to the NG-RAN. See box 224.

[0174] In both embodiments, the external identifier (GPSI in one example) of the roaming UE provided by the AF should be mapped to an internal identifier (such as SUPI). Using the new service operation of the UDM, the NEF, the UDM in the VPLMN, the MB-SMF (as shown in the process), or the SMF should contact the UDM in the HPLMN of each roaming UE and request the SUPI that matches the GPSI.

[0175] In Technique 2, there is a database (such as UDR 99-6V) in the VPLMN 110 that stores information about the roaming UEs authorized to use the MBS session and / or the MBS assistance information of the roaming users. See Figure 4 , which is an example of a signaling diagram showing the second technique (Technique 2). The signaling and operations performed on, from, or by the UDR 99-6V are indicated by the same numbers as in the other figures, but with "-1" added to them.

[0176] 1. The AF 80 connected to the VPLMN 110 provides the GPSI of the UE entitled to use the MBS session and / or the MBS assistance information of the roaming user to the UDM in the VPLMN via the NEF through a parameter provisioning procedure. See signaling 302, 304, 202, 306, and 308.

[0177] 2. The UDM 99-5V in the VPLMN identifies the roaming user via the MCC / MNC part of the GPSI or via the lack of a UDM entry. See box 310.

[0178] 3. The UDM 99-5V in the VPLMN 110 discovers the database that processes the MBS multicast session via the NRF (if multiple databases process the MBS multicast session, each database can be assigned a series of multicast session IDs registered by the UDM at the NRF, and then the UDM uses the MBS session ID for selection), and indicates to the database the roaming users entitled to use the MBS multicast session and / or the MBS assistance information of the roaming users in signaling 312-1.

[0179] 4. The SMF 99-2V discovers the database that processes the MBS multicast session via the NRF (if multiple databases process the MBS multicast session, each database can be assigned a series of multicast session IDs registered by the database at the NRF, and then the UDM uses the MBS session ID for selection), and obtains information about the MBS session from the database, for example, when the MBS session information from the MB-SMF indicates that the MBS session is not open to any UE. Preferably, the SMF subscribes to the information about the MBS session and is also notified when the information stored in the database changes. The subscription can occur in signaling 220-1 from the SMF 99-2V to the UDR 99-6V, and the notification is obtained via signaling 222-1 from the UDR 99-6V to the SMF 99-2V.

[0180] 5. The SMF 99-2V uses this information to authenticate the roaming user (UE 10) attempting to join the MBS session and / or provide assistance information to the NG-RAN. See box 224.

[0181] Signaling 210-1 and 212-1 are performed between the UDR 80 and the UDM 99-5H (for example, not between the MB-SMF 99-3V and the UDM 99-5H in Figure 2 ), and the UDR 99-6V performs box 214-1 (instead of the MB-SMF 99-3V as in Figure 2 ).

[0182] The external identifier (e.g., GPSI) of a roaming UE provided by the AF shall be mapped to an internal identifier (e.g., SUPI). Using the new service operation of the UDM, it is recommended that the NEF, the UDM in the VPLMN, the database, or the SMF shall contact the UDM in the HPLMN of each roaming UE and request the SUPI that matches the GPSI.

[0183] Go to Figure 4A , which figure helps to explain Figure 3 and 4 Some of the operations and signaling in. For Figure 3 and 4 In box 310 of, Figure 4A Box 410 of helps to explain the operations there. In box 410, the UDM in the VPLMN receives a request to store information related to an MBS session that contains the identifier of the UE, where the identifier of the UE includes the identifier of the roaming UE and may also include the identifier of a non-roaming UE. In box 420, the UDM identifies the roaming UE and sends a request to the MB-SMF ( Figure 3 ) or the UDR ( Figure 4 ) to store the relevant authorization information and / or auxiliary information. Figure 4A Box 420 in partly relates to box 310 and partly relates to Figure 3 and 4 The signaling that occurs after box 310 in.

[0184] Regarding technology 3, this example has a UDM in the HPLMN that stores information about roaming UEs that are authorized to use the MBS session and / or MBS auxiliary information for roaming users. This example has two embodiments.

[0185] Combined with Figure 5 Describes Embodiment 1, Figure 5 Is an example of a signaling diagram showing the third technology (Technology 3) and the first embodiment (Embodiment 1) of this technology.

[0186] 1A. The AF 80 connected to the VPLMN 110 identifies the roaming user via the MCC / MNC part of the GPSI (see box 310), and for the roaming user, uses the NEF in the corresponding HPLMN for the parameter provisioning process to indicate to the NEF the GPSI of the roaming user authorized to use the MBS multicast session and / or the MBS assistance information of the roaming user. The AF may include the service class and the serving VPLMN. This is part of the initial process, including boxes 302, 304, 202, and 306-1. In box 306-1, this has the signaling Nnef_ParameterProvision_Create request (MBS session ID, GPSI of the roaming UE authorized to access the MBS service, MBS assistance information (GPSI of the roaming UE, VPLMN ID, service class)) from the AF 80 to the NEF 99-4H in the HPLMN 120.

[0187] 1B. The NEF 99-4H in the HPLMN 120 forwards the parameter provisioning to the UDM 99-5H in the HPLMN 120. See the signaling 312-2 Nudm_ParameterProvision_Create request (MBS session ID, GPSI of the roaming UE authorized to access the MBS service, MBS assistance information (GPSI of the roaming UE, VPLMN ID, service class)).

[0188] 1C. The UDM 99-5H in the HPLMN 120 stores that the user is authorized to use the indicated MBS session and / or the MBS assistance information of the roaming user, for example, as part of the user subscription data. The UDM 99-5H in the HPLMN 120 can also check whether the user is authorized to use the MBS service by considering the configuration information about the user being allowed to access the MBS service when roaming, and possibly the configuration information about the service class and the VPLMN applying this information, and otherwise reject the storage request. See box 502, where the UDM 99-5H maps the GPSI to the SUPI; and box 504, where the UDM 99-5H checks whether the UE is authorized for the MBS service in the VPLMN. Also see box 506, where the UDM 99-5H stores the SUPI and MBS assistance information (SUPI of the roaming UE) of the roaming UE authorized to access the MBS service.

[0189] In box 508, there is a PDU session establishment, see clause 7.2.1.2 of 3GPP TS23.247. Signaling 510 and 512 are optional. In signaling 510, there is a Nudm_SDM_Get request message (SUPI) from SMG 99-2V to UDM 99-5H, and UDM 99-5H responds with a Nudm_SDM_Get response (MBS subscription information, MBS assistance information).

[0190] Regarding Example 2, it is described in part by Figure 6 this. Figure 6 is an example of a signaling diagram showing a third technology (Technology 3) and a second embodiment (Example 2) of this technology.

[0191] 1A. AF 80 provides the GPSI of the UE authorized to use the MBS session and / or the MBS assistance information of the roaming user to UDM99-5V in VPLMN 110 via the NEF 99-4V in VPLMN 110 through a parameter provisioning process. See signaling 306 and 602, which in this example occur after signaling 302, 304, and 202.

[0192] 1B. UDM 9-6V in VPLMN 110 identifies the roaming user via the MCC / MNC part of the GPSI or via the lack of a UDM entry. See box 310, which is executed after signaling 360 and the reception of the corresponding GPSI.

[0193] 1C. For a roaming user, UDM 99-5V in VPLMN 110 discovers the UDM 99-5H in HPLMN 120 that processes these users via the NRF, and for each such user, indicates to the UDM 99-5H in HPLMN 120 that the user is authorized to use the MBS multicast session and / or the MBS assistance information of these users. See signaling 604, in which UDM 99-5V sends the following message to UDM 99-5H: NudmParameterProvision_Create request (MBS session ID, GPSI of the roaming UE authorized to access the MBS service, MBS assistance information (GPSI of the roaming UE, VPLMN ID)).

[0194] In the 1D HPLMN, the UDM stores the MBS sessions that the user is authorized to use and / or the MBS assistance information of the user, such as as part of the user subscription data. The UDM in the HPLMN can also check whether the user is authorized to use the MBS service by comparing the configuration information regarding the user's access to MBS services when roaming, and the configuration information regarding the service class and the VPLMN applying this information, and otherwise reject the storage request. See box 502, where the UDM 99-5H maps the GPSI to the SUPI; and box 504, where the UDM 99-5H checks whether the UE is authorized for MBS services in the VPLMN. In box 506, the UDM 99-5H stores the SUPI of the roaming UE authorized to access the MBS service, the MBS assistance information (e.g., the SUPI of the roaming UE).

[0195] 2. When the roaming UE 10 registers, the SMF 99-2V in the VPLMN 110 can obtain / subscribe to the user subscription information (including information about the MBS session) from the UDM in the HPLMN. See signaling 508, 510, and 512.

[0196] 3. The SMF 99-2V uses this information to authenticate the user attempting to join the MBS session and / or provide assistance information to the NG-RAN 70. For example, in signaling 606, the roaming UE 10 sends a message to the AMF 99-1V to store the SUPI of the roaming UE authorized to access the MBS service, the MBS assistance information (the SUPI of the roaming UE). The AMF 99-1V responds by sending signaling 608 Nsmf_PDUSession_UpdateSMContext request to the SMF 99-2V, and then the SMF 99-2V responds by performing an authentication check associated with the UE 10 in box 224.

[0197] Reference Figure 6A to Figure 5 and 6 is a flowchart to help explain the checks for the roaming UE in Figure 5 and 6 This check can be performed through box 504 of Figure 5 and 6 and an example is shown in box 627, where for each received general public subscription identifier of the roaming UE, the UDM uses at least one of the following to check whether the roaming UE is authorized to access the MBS service: the received VPLMN ID, the received service class, the stored information about whether the UE is entitled to receive MBS services when roaming, the stored information about the VPLMN from which the UE is entitled to receive MBS services when roaming, or the stored information about the service class of the MBS services that the UE is entitled to receive when roaming.

[0198] Now, Technology 4 is provided. Figure 7 It is an example of a signaling diagram showing the Fourth Technology (Technology 4). In one example of this technology, SMF 99-2V stores MBS assistance information of roaming UEs and / or roaming users authorized to use MBS sessions.

[0199] 1. The AF 80 connected to the VPLMN 110 provides the GPSI of the UE authorized to use the MBS session and / or the MBS assistance information of the roaming user to the UDM in the VPLMN via the NEF through a parameter provisioning procedure. Referring to signaling 306, in this example, signaling 306 occurs after signaling 302, 304, and 202.

[0200] 2. The UDM 99-5V in the VPLMN identifies the roaming user 10 via the MCC / MNC part of the GPSI or via the lack of a UDM entry. Refer to box 310.

[0201] 3. The UDM 99-5V in the VPLMN 110 discovers the SMF 99-2V that processes the roaming user via the UDM 99-5H in the HPLMN 120, and indicates to each SMF the roaming users authorized to use the MBS multicast session served by the SMF 99-2V and / or the MBS assistance information of the roaming users. If the UE is served by multiple SMFs 99-2V of the VPLMN, the UDM in the VPLMN provides the information related to this UE to all these SMFs. As long as the SMF serves the roaming UE, the SMF stores the information related to the roaming UE. Referring to signaling 702, where the UDM 99-5V sends a Nudm_UECM_Get request (NFtype = SMF, GPSI) message to the UDM 99-5H, and the UDM 99-5H returns a Nudm_UECM_Get response (SMF ID SUPI) in signaling 704. In signaling 705, the UDM 99-5V sends a Nsmf_ParameterProvision_Create request message (MBS session ID, SUPI of the roaming UE authorized to access the MBS service, MBS assistance information (SUPI of the roaming UE)) to the SMF 99-2V. For storage, the SMF 99-2V stores the SUPI of the roaming UE authorized to access the MBS service and the MBS assistance information (e.g., SUPI of the roaming UE). Refer to box 708.

[0202] 4. The SMF 99-2V uses this information to authenticate the roaming user attempting to join the MBS session and / or provide assistance information to the NG-RAN. Refer to the authorization check in box 224, which responds to the signaling in 606 and 608 and has a response via signaling 226.

[0203] Reference Figure 8 , which is a flowchart showing a part of Technique 1 at the MB-SMF. For example, see Figure 2 Boxes 206 and 208 of. In Box 810, this includes: at the MB-SMF in the VPLMN of the roaming UE, for an MBS session, storing at least one of the following: information about the roaming UE authorized to use the MBS session, or corresponding information about MBS assistance for the MBS session related to the roaming UE. Box 815 includes: the MB-SMF receiving a request for context state subscription for the MBS session from the SMF in the VPLMN. Box 820 includes: the MB-SMF using the stored information and in response to the request, sending at least one of the following: one or more identifiers of the UE authorized to access the MBS session, or information about MBS assistance for the MBS session including the identifier of the related roaming UE.

[0204] Figure 8 An example of the process of may further include: wherein, one or more identifiers include a subscription permanent identifier, and the method further includes: the MB-SMF receiving the identification of the MBS session and at least one of the following: the general public subscription identifier of the roaming UE authorized to access the MBS session, or information about MBS assistance for the MBS session including the general public subscription identifier of the related roaming UE; the MB-SMF sending a request to the UDM in the HPLMN to convert the general public subscription identifier of the selected one or more roaming UEs into a subscription permanent identifier; and the MB-SMF receiving from the UDM in the HPLMN the subscription permanent identifier corresponding to the selected one or more roaming UEs for sending one or more identifiers of the selected roaming UEs. In addition, the storage includes: storing the subscription permanent identifier corresponding to the selected one or more roaming UEs. Consider Figure 2 Boxes 208, 210, and 212 of.

[0205] The example of the previous paragraph has a further example, wherein the MB-SMF receives the identification of the MBS session and at least one of the following in the following manner: the general public subscription identifier of the roaming UE authorized to access the MBS session as an MBS service, and the corresponding information about MBS assistance for the MBS session including the general public subscription identifier of the related roaming user: receiving from the NEF using one of the message for creating the MBS session or the message for modifying the MBS session; or receiving from the UDM in the VPLMN using the message providing parameters related to the MBS session. For example, see Figure 2 Box 208 of Figure 3 Box 312 of.

[0206] Figure 9 It is a flowchart showing the corresponding part of Technique 1 at the SMF. Block 910 includes: the SMF in the VPLMN of the roaming UE receiving an indication from the AMF in the VPLMN that the roaming UE wants to join an MBS session. Block 920 includes: the SMF sending a request for information about the MBS session to the MB-SMF in the VPLMN. Block 930 includes: the SMF receiving from the MB-SMF in the VPLMN at least one of the following: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including the identifier of the relevant roaming UE. Block 940 includes: the SMF performing an authorization check to determine whether the roaming UE is authorized to access the MBS session. Block 950 includes: the SMF sending a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session. For example, see Figure 2 Blocks 218, 220, 222, 224, etc. of

[0207] Figure 9 Another example of the process of

[0208] is: wherein, one or more identifiers include a subscription permanent identifier. Further examples in this paragraph and the previous paragraph include: wherein, the authorization check for determining whether the roaming UE that wants to join the MBS session is authorized to access the MBS session considers whether one identifier among one or more received identifiers of the roaming UE authorized to access the MBS session is included in the identifier of the roaming UE received in the indication.

[0209] Figure 10 It is a flowchart showing the corresponding part of Technique 1 at the NEF. Figure 10 at least partially related to Figure 2 the operations performed by the NEF in

[0210] Figure 11 is applied toFigure 3 and 4 Flowchart of operations of the UDM. The process includes block 1110, which includes: receiving, at the UDM in the VPLMN of the roaming UE, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: one or more identifiers corresponding to one or more UEs authorized to access the MBS session, and information about MBS assistance for the MBS session including the identifier of the associated UE. In block 1115, this includes: determining, by the UDM, an inbound roaming UE from at least one of the following: one or more UEs authorized to access the MBS session, and a UE associated with the information about MBS assistance. Block 1120 includes: sending, by the UDM, a request to store information related to the MBS session to the MB-SMF or UDR, the request including the identifier of the MBS session and at least one of the following: an identifier corresponding to the determined inbound roaming UE authorized to access the MBS session, and information about MBS assistance for the MBS session including the identifier of the determined inbound roaming UE.

[0211] Reference Figure 12 to Figure 4 Flowchart of operations of the UDR that is at least applicable to

[0212] As another example, Figure 12The flowchart includes: one or more identifiers including a subscription permanent identifier. Additionally, the method further includes: the UDR receiving the identification of the MBS session and at least one of the following: the general public subscription identifier of the roaming UE authorized to access the MBS session, and information about MBS assistance for the MBS session including the general public subscription identifier of the associated roaming UE; the UDR sending a request to the UDM in the HPLMN to convert the general public subscription identifier of the selected one or more UEs into a subscription permanent identifier; and the UDR receiving from the UDM in the HPLMN the subscription permanent identifier corresponding to the selected one or more UEs for sending one or more identifiers of the UE. The storage includes: storing the subscription permanent identifier corresponding to the selected one or more UEs.

[0213] Figure 13 is at least applied to Figure 4 The flowchart of the operations of the SMF. Block 1310 includes: the SMF in the VPLMN of the roaming UE receiving an indication from the AMF in the VPLMN that the roaming UE wants to join the MBS session, and block 1320 includes: the SMF sending a request for a subscription for information related to the MBS session to the UDR in the VPLMN, the request including the session ID of the MBS session. Block 1330 includes: the SMF receiving from the UDR in the VPLMN in response to the request information including at least one of the following: one or more identifiers of the roaming UE authorized to access the MBS session corresponding to the session ID, or information about MBS assistance for the MBS session including the identifier of the associated roaming UE. Block 1340 includes: the SMF performing an authorization check for the roaming UE to see if the roaming UE is authorized to access the MBS session. Block 1350 includes: the SMF sending a response to the indication that the roaming UE wants to join the MBS session to the AMF, the information for MBS assistance indicating that the UE is authorized to join the MBS session.

[0214] Another example of the process is: wherein, the authorization check for determining whether the roaming UE wanting to join the MBS session is authorized to access the MBS session takes into account whether one of the one or more identifiers of the roaming UE authorized to access the MBS session includes the identifier of the roaming UE. Further examples of this process and the previous example include: wherein, the response to the indication that the roaming UE wants to join the MBS session includes MBS assistance information for the MBS session, the MBS assistance information for the MBS session being based on the received information about MBS assistance including the identifier of the roaming UE wanting to join the MBS session.

[0215] Figure 14 is at least applied to Figure 5 and6 Flowchart of operations of the UDM. In block 1410, this includes: at the UDM in the HPLMN of the roaming UE, receiving, from the NEF in the HPLMN or the UDM in the VPLMN, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: the general public subscription identifier of the roaming UE authorized to access the MBS session, information for MBS assistance, the information including the general public subscription identifier of the relevant roaming UE, the VPLMN ID, and the service class. Block 1420 includes: the UDM using at least one of the following to check whether the roaming UE is authorized to access the MBS service of the MBS service for the separately received general public subscription identifier of the roaming UE: the received VPLMN ID, the received service class, the stored information on whether the UE is entitled to receive MBS services when roaming, the stored information on the VPLMN from which the UE is entitled to receive MBS services when roaming, or the stored information on the service class of the MBS services the UE is entitled to receive when roaming. Block 1430 includes: the UDM storing, for an individual UE among those roaming UEs authorized to receive MBS services in the VPLMN, at least one of the following: the identifier of the authorized MBS session corresponding to the MBS service, or the information for MBS assistance for the MBS session.

[0216] An example of process 1430 may further include: wherein the stored information includes at least one of the following: the identifier of the authorized MBS service, and the information for MBS assistance related to the roaming UE identified by using the subscription permanent identifier of the roaming UE, and wherein the method further includes: the UDM mapping the general public subscription identifier of the roaming UE authorized to access the MBS session to the subscription permanent identifier such that the subscription permanent identifier is stored corresponding to the roaming UE authorized to access the MBS session.

[0217] Another example that may be applied to the previous two paragraphs may further include: the UDM receiving, from the SMF in the VPLMN, a request with an identifier of the roaming UE; and sending, from the UDM to the SMF, a response to the request with an identifier of the roaming UE, and the stored information includes at least one of the following: the identifier of the authorized MBS session, and the information for MBS assistance for the MBS session.

[0218] Figure 15 is at least applied to Figure 5Flowchart of the operation of the AF. Block 1510 includes: at the AF that provides data for the MBS session in the PLMN, identifying UEs with different PLMNs as the HPLMN that are authorized to participate in the MBS session and the HPLMNs of these UEs. Block 1520 includes: sending a request to provide data for the MBS session from the AF to the NEF in the HPLMN, the request including at least one of the following items: the identifier of the MBS session, and at least one of the following items: the general public subscription identifier of a roaming UE authorized to access the MBS session from the HPLMN, information for MBS assistance including the general public subscription identifier of the relevant roaming UE from the HPLMN, the PLMN ID of the PLMN providing the MBS session, and the service class.

[0219] Figure 16 is at least applied to Figure 5 Flowchart of the operation of the UDM. Block 1610 includes: at the UDM in the PLMN that provides the MBS session, receiving a request to provide data for the MBS session from the NEF in the PLMN, the request including at least one of the following items: the identifier of the MBS session, and at least one of the following items: the general public subscription identifier of a UE authorized to access the MBS session, information for MBS assistance including the general public subscription identifier of the relevant UE, or the service class. Block 1620 includes: at the UDM, identifying the general public subscription identifiers of UEs with different PLMNs as the HPLMN and the HPLMNs of these UEs. Block 1630 includes: sending a request to provide data for the MBS session from the UDM in the PLMN to the UDM in the HPLMN, the request including the identifier of the MBS session, and at least one of the following items: the general public subscription identifier of a roaming UE authorized to access the MBS session from the HPLMN, information for MBS assistance including the general public subscription identifier of the relevant roaming UE from the HPLMN, the PLMN ID of the PLMN providing the MBS session, or the service class.

[0220] Figure 17 is at least applied to Figure 5Flowchart of the operation of the UDM. Block 1710 includes: at the UDM in the PLMN providing the MBS session, receiving from the NEF in the PLMN a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, or information for MBS assistance including the general public subscription identifier of the associated UE. Block 1720 includes: at the UDM, identifying the general public subscription identifiers of UEs having a different PLMN as the HPLMN and the HPLMNs of these UEs. Block 1730 includes: for each separately identified UE, sending from the UDM in the PLMN to the UDM in the HPLMN of the identified UE a request to provide an identifier of the SMF for processing the identified UE, the request including the general public subscription identifier of the identified UE. Block 1740 includes: for each separately identified UE, receiving at the UDM in the PLMN from the UDM in the HPLMN of the identified UE a response including at least one identifier of the SMF for processing the identified UE and the subscription permanent identifier of the identified UE. Block 1750 includes: for each separately identified UE, sending from the UDM in the PLMN to the SMF a request to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following: the subscription permanent identifier of the identified roaming UE indicating that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance including the subscription permanent identifier of the identified roaming UE.

[0221] Figure 18 is at least applied to Figure 7Flowchart of operations of the SMF. Block 1810 includes: receiving, by the SMF in the VPLMN of the roaming UE, from the UDM in the VPLMN, a request to provide data for an MBS session, the request including an identifier of the MBS session and at least one of the following: a subscription permanent identifier of the roaming UE indicating that the roaming UE is authorized to access the MBS session, and information for MBS assistance including the subscription permanent identifier of the roaming UE. Block 1820 includes: storing, by the SMF, the received identifier of the MBS session and at least one of the following: the received subscription permanent identifier of the roaming UE indicating that the roaming UE is authorized to access the MBS session, or the received information for MBS assistance including the subscription permanent identifier of the roaming UE. Block 1830 includes: receiving, by the SMF, from the AMF in the VPLMN, an indication that the roaming UE wants to join the MBS session. Block 1840 includes: performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session. Block 1850 includes: sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session.

[0222] Figure 18 The process may further include: wherein, the authorization check to determine whether the roaming UE that wants to join the MBS session is authorized to access the MBS session takes into account whether one or more identifiers of the roaming UE that are authorized to access the MBS session and stored include the identifier of the roaming UE.

[0223] The processes of the first two paragraphs may further include: wherein, if one or more identifiers of the roaming UE related to the information for MBS assistance and stored include the identifier of the roaming UE that wants to join the MBS session, the response to the indication that the roaming UE wants to join the MBS session includes the information for MBS assistance for the MBS session.

[0224] Figure 13-18 The processes and other examples of these processes may be implemented by a computer program, the computer program including instructions that, when the computer program runs on a device, are used to execute the method of any process. The computer program may be a computer program product including a computer-readable medium, the computer-readable medium carrying instructions contained therein for use with the device. The computer program may be directly loaded into the internal memory of the device.

[0225] Without in any way limiting the scope, interpretation, or application of the claims that follow, the technical effects and / or advantages of one or more example embodiments disclosed herein are: At least for Technique 1, the MBS service in the VPLMN has no impact on the HPLMN, and no new network entities are used. Another technical effect and / or advantage of one or more example embodiments disclosed herein is: For example, at least for Technique 2, the MBS service in the VPLMN has no impact on the HPLMN. Another technical effect and / or advantage of one or more example embodiments disclosed herein is: At least for Technique 3, the impact on existing processes is minimal.

[0226] The following are additional examples.

[0227] Example 1. An apparatus, comprising components for performing the following operations: At an MB-SMF in the VPLMN of a roaming UE, for an MBS session, store at least one of the following: information about a roaming UE authorized to use the MBS session, or corresponding information about MBS assistance for the MBS session related to the roaming UE; receive, by the MB-SMF from an SMF in the VPLMN, a request for context state subscription for the MBS session; and send, by the MB-SMF using the stored information and in response to the request, at least one of the following: one or more identifiers of UEs authorized to access the MBS session, or information about MBS assistance for the MBS session including the identifier of the associated roaming UE.

[0228] Example 2. The apparatus according to Example 1, wherein: The one or more identifiers include a subscription permanent identifier; the components are further configured to perform: receive, by the MB-SMF, an identification of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, or information about MBS assistance for the MBS session including the general public subscription identifier of a roaming UE authorized to access the MBS session; send, by the MB-SMF to a UDM in the HPLMN, a request to convert the general public subscription identifier of the selected one or more roaming UEs into a subscription permanent identifier; and receive, by the MB-SMF from the UDM in the HPLMN, a subscription permanent identifier corresponding to the selected one or more roaming UEs for sending the one or more identifiers of the selected roaming UEs; and the storing includes: storing a subscription permanent identifier corresponding to the selected one or more roaming UEs.

[0229] Example 3. The apparatus according to Example 2, wherein the MB-SMF receives the identifier of the MBS session and at least one of the following in the following manner: the general public subscription identifier of the UE authorized to access the MBS session that is an MBS service, and the corresponding information about the MBS assistance for the MBS session including the identifier of the relevant roaming user: received from the NEF using one of the message for creating the MBS session or the message for modifying the MBS session; or received from the UDM in the VPLMN using the message providing the parameters related to the MBS session.

[0230] Example 4. An apparatus, comprising components for performing the following operations: the SMF in the VPLMN of the roaming UE receives an indication from the AMF in the VPLMN that the roaming UE wants to join an MBS session; the SMF sends a request for information about the MBS session to the MB-SMF in the VPLMN; the SMF receives from the MB-SMF in the VPLMN at least one of the following: one or more identifiers of the UE authorized to access the MBS session, or the information about the MBS assistance for the MBS session including the identifier of the relevant roaming UE; the SMF performs an authorization check to determine whether the roaming UE is authorized to access the MBS session; and the SMF sends a response to the indication that the roaming UE wants to join the MBS session to the AMF, and the response indicates that the UE is authorized to join the MBS session.

[0231] Example 5. The apparatus according to Example 4, wherein the one or more identifiers include the subscription permanent identifier.

[0232] Example 6. The apparatus according to Example 4 or 5, wherein the authorization check for determining whether the roaming UE that wants to join the MBS session is authorized to access the MBS session considers whether one of the one or more received identifiers of the roaming UE authorized to access the MBS session is included in the identifier of the roaming UE received in the indication.

[0233] Example 7. The apparatus according to any one of Examples 4 to 6, wherein the response to the indication that the roaming UE wants to join the MBS session includes the MBS assistance information for the MBS session, and the MBS assistance information for the MBS session is based on the received identifier of the roaming UE related to the information about the MBS assistance including the identifier of the roaming UE that wants to join the MBS session.

[0234] Example 8. A device includes components for performing the following operations: receiving, at a NEF, from an AF, a message for creating or modifying an MBS session, the message including an identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, or MBS assistance information for the MBS session related to the roaming UE; and forwarding the message from the NEF to an MB-SMF in the VPLMN of the roaming UE.

[0235] Example 9. A device includes components for performing the following operations: receiving, at a UDM in the VPLMN of a roaming UE, a request to store information related to an MBS session, the request including an identifier of the MBS session and at least one of the following: one or more identifiers corresponding to one or more UEs authorized to access the MBS session, and MBS assistance information for the MBS session including an identifier of a related UE; determining, by the UDM, an inbound roaming UE from at least one of the following: one or more UEs authorized to access the MBS session, and a UE related to the MBS assistance information; and sending, by the UDM, a request to store information related to the MBS session to an MB-SMF or a UDR, the request including an identifier of the MBS session and at least one of the following: an identifier corresponding to the determined inbound roaming UE authorized to access the MBS session, and MBS assistance information for the MBS session including an identifier of the determined inbound roaming UE.

[0236] Example 10. A device includes components for performing the following operations: storing, at a UDR in the VPLMN of a roaming UE, an identifier of an MBS session and at least one of the following: one or more identifiers corresponding to one or more roaming UEs authorized to access the MBS session, or MBS assistance information for the MBS session including an identifier of a related roaming UE; receiving, by the UDR, from an SMF in the VPLMN, a request for a subscription for the MBS session, the request including a session ID of the MBS session; and sending, by the UDR, in response to the request and using the stored information, at least one of the following to the SMF: one or more identifiers of roaming UEs authorized to access the MBS session corresponding to the session ID, and MBS assistance information for the MBS session including an identifier of a related roaming UE.

[0237] Example 11. The apparatus according to Example 10, wherein: one or more identifiers include a subscription permanent identifier; the component is further configured to perform: receiving, by the UDR, an identification of an MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session, and information on MBS assistance for the MBS session including the general public subscription identifier of the associated roaming UE; sending, by the UDR, a request to the UDM in the HPLMN to convert the general public subscription identifier of the selected one or more UEs into a subscription permanent identifier; and receiving, by the UDR, from the UDM in the HPLMN, the subscription permanent identifier corresponding to the selected one or more UEs for sending one or more identifiers of the UE; and the storage includes: storing the subscription permanent identifier corresponding to the selected one or more UEs.

[0238] Example 12. An apparatus, including components for performing the following operations: receiving, by the SMF in the VPLMN of a roaming UE, an indication from the AMF in the VPLMN that the roaming UE wants to join an MBS session; sending, by the SMF, a request for a subscription for information related to the MBS session to the UDR in the VPLMN, the request including the session ID of the MBS session; receiving, by the SMF in response to the request, information including at least one of the following from the UDR in the VPLMN: one or more identifiers of a roaming UE authorized to access the MBS session corresponding to the session ID, or information on MBS assistance for the MBS session including the identifier of the associated roaming UE; performing, by the SMF, an authorization check for the roaming UE to see if the roaming UE is authorized to access the MBS session; and sending, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the information on MBS assistance for the MBS session indicating that the UE is authorized to join the MBS session.

[0239] Example 13. The apparatus according to Example 12, wherein the authorization check for determining whether a roaming UE that wants to join an MBS session is authorized to access the MBS session takes into account whether one of the one or more received identifiers of the roaming UE authorized to access the MBS session includes the identifier of the roaming UE.

[0240] Example 14. The apparatus according to any one of Examples 12 to 13, wherein the response to the indication that the roaming UE wants to join the MBS session includes MBS assistance information for the MBS session, the MBS assistance information for the MBS session being based on the received information on MBS assistance including the identifier of the roaming UE that wants to join the MBS session.

[0241] Example 15. A device includes components for performing the following operations: at the UDM in the HPLMN of a roaming UE, receive a request to store information related to an MBS session from the NEF in the HPLMN or the UDM in the VPLMN, the request including an identifier of the MBS session and at least one of the following: a general public subscription identifier of the roaming UE authorized to access the MBS session, information for MBS assistance, the information including the general public subscription identifier of the relevant roaming UE, the VPLMN ID, and the service class; use at least one of the following by the UDM for the general public subscription identifier separately received for the roaming UE to check whether the roaming UE is authorized to access the MBS service of the MBS service: the received VPLMN ID, the received service class, the stored information on whether the UE is entitled to receive the MBS service when roaming, the stored information on the VPLMN from which the UE is entitled to receive the MBS service when roaming, or the stored information on the service class of the MBS service that the UE is entitled to receive when roaming; and store at least one of the following by the UDM for an individual UE among those roaming UEs authorized to receive the MBS service in the VPLMN: an identifier of an authorized MBS session corresponding to the MBS service, or information for MBS assistance for the MBS session.

[0242] Example 16. The device according to Example 15, wherein the stored information includes at least one of the following: an identifier of an authorized MBS service, and information for MBS assistance related to a roaming UE identified by using the subscription permanent identifier of the roaming UE, and wherein the component is further configured to perform: map, by the UDM, the general public subscription identifier of the roaming UE authorized to access the MBS session to the subscription permanent identifier such that the subscription permanent identifier is stored corresponding to the roaming UE authorized to access the MBS session.

[0243] Example 17. The device according to any one of Examples 15 or 16, wherein the component is further configured to perform: receive, by the UDM, a request with an identifier of a roaming UE from the SMF in the VPLMN; and send, from the UDM to the SMF, a response to the request with an identifier of a roaming UE, and the stored information includes at least one of the following: an identifier of an authorized MBS session, and information for MBS assistance for the MBS session.

[0244] Example 18. A device includes components for performing the following operations: at an AF that provides data for an MBS session in a PLMN, identifying UEs with different PLMNs as their HPLMNs that are authorized to participate in the MBS session and the HPLMNs of the UEs; and sending, from the AF to a NEF in the HPLMN, a request for providing data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session from the HPLMN, MBS assistance information including the general public subscription identifier of a related roaming UE from the HPLMN, a PLMN ID of the PLMN providing the MBS session, and a service class.

[0245] Example 19. A device includes components for performing the following operations: at a UDM in a PLMN that provides an MBS session, receiving, from a NEF in the PLMN, a request for providing data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, MBS assistance information including the general public subscription identifier of a related UE, or a service class; at the UDM, identifying the general public subscription identifier of a UE with a different PLMN as its HPLMN and the HPLMN of the UE; and sending, from the UDM in the PLMN to a UDM in the HPLMN, a request for providing data for the MBS session, the request including an identifier of the MBS session and at least one of the following: a general public subscription identifier of a roaming UE authorized to access the MBS session from the HPLMN, MBS assistance information including the general public subscription identifier of a related roaming UE from the HPLMN, a PLMN ID of the PLMN providing the MBS session, or a service class.

[0246] Example 20. A device includes components for performing the following operations: at a UDM in a PLMN providing an MBS session, receive from an NEF in the PLMN a request to provide data for the MBS session, the request including at least one of the following: an identifier of the MBS session, and at least one of the following: a general public subscription identifier of a UE authorized to access the MBS session, or information for MBS assistance including the general public subscription identifier of the associated UE; at the UDM, identify the general public subscription identifier of a UE having a different PLMN as the HPLMN and the HPLMN of the UE; for each separately identified UE, send from the UDM in the PLMN to the UDM in the HPLMN of the identified UE a request to provide an identifier of an SMF for processing the identified UE, the request including the general public subscription identifier of the identified UE; for each separately identified UE, at the UDM in the PLMN receive from the UDM in the HPLMN of the identified UE a response, the response including at least one identifier of an SMF for processing the identified UE, and the subscription permanent identifier of the identified UE; and for each separately identified UE, send from the UDM in the PLMN to an SMF a request to provide data for the MBS session, the request including the identifier of the MBS session and at least one of the following: the subscription permanent identifier of the identified roaming UE indicating that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance including the subscription permanent identifier of the identified roaming UE.

[0247] Example 21. A device includes components for performing the following operations: receive, by an SMF in a VPLMN of a roaming UE, from a UDM in the VPLMN a request to provide data for an MBS session, the request including the identifier of the MBS session and at least one of the following: the subscription permanent identifier of the roaming UE indicating that the roaming UE is authorized to access the MBS session, and information for MBS assistance including the subscription permanent identifier of the roaming UE; store, by the SMF, the received identifier of the MBS session and at least one of the following: the received subscription permanent identifier of the roaming UE indicating that the roaming UE is authorized to access the MBS session, or the received information for MBS assistance including the subscription permanent identifier of the roaming UE; receive, by the SMF, from an AMF in the VPLMN an indication that the roaming UE wants to join the MBS session; perform, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session; and send, by the SMF, a response to the indication that the roaming UE wants to join the MBS session to the AMF, the response indicating that the UE is authorized to join the MBS session.

[0248] Example 22. The apparatus according to Example 21, wherein the authorization check for determining whether a roaming UE that wants to join an MBS session is authorized to access the MBS session takes into account whether one or more identifiers of roaming UEs stored as being authorized to access the MBS session include the identifier of the roaming UE.

[0249] Example 23. The apparatus according to any one of Examples 21 to 22, wherein if one or more identifiers of a roaming UE stored as being related to MBS assistance information include the identifier of the roaming UE that wants to join an MBS session, the response to the indication that the roaming UE wants to join the MBS session includes MBS assistance information for the MBS session.

[0250] Example 24. The apparatus according to any of the preceding apparatus examples, wherein the component includes: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform.

[0251] As used in this application, the term "circuitry" can refer to one or more or all of the following:

[0252] (a) A pure hardware circuit implementation (e.g., an implementation in pure analog and / or digital circuitry), and

[0253] (b) A combination of hardware circuitry and software, such as, where applicable: (i) a combination of analog and / or digital hardware circuitry with software / firmware, and (ii) any part of a hardware processor (including a digital signal processor), software, and memory that work together to cause an apparatus (e.g., a mobile phone or a server) to perform various functions, and

[0254] (c) Hardware circuitry and / or a processor, such as a microprocessor or a part of a microprocessor, that requires software (e.g., firmware) to operate, but where the software may not be present when not needed for operation.

[0255] This definition of "circuitry" applies to all uses of the term in this application (including in any claims). As a further example, as used in this application, the term "circuitry" also encompasses an implementation of only hardware circuitry or a processor (or processors) or a part of a hardware circuitry or a processor together with its accompanying software and / or firmware. The term "circuitry" also encompasses (e.g., and if applicable to a particular claim element) a baseband integrated circuit or a processor integrated circuit for a mobile device, or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0256] Embodiments of the present disclosure may be implemented in software (executed by one or more processors), hardware (such as an application specific integrated circuit), or a combination of software and hardware. In one example embodiment, software (such as application logic, instruction sets) is maintained on any of a variety of conventional computer-readable media. In the context of this document, "computer-readable medium" may be any medium or component that can contain, store, transmit, propagate, or transport instructions for use by or in connection with an instruction execution system, apparatus, or device (such as a computer), and an example of a computer is described and illustrated in Figure 1A . The computer-readable medium may include a computer-readable storage medium (such as memories 15, 75, and 95 or other devices), which can be any medium or component that can contain, store, and / or transport instructions for use by or in connection with an instruction execution system, apparatus, or device (such as a computer). The computer-readable storage medium does not include propagated signals and can thus be regarded as non-transitory. As used herein, the term "non-transitory" is a limitation on the medium itself (i.e., tangible, rather than a signal), rather than a limitation on the persistence of data storage (e.g., RAM (Random Access Memory) versus ROM (Read Only Memory)).

[0257] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Additionally, if desired, one or more of the functions described above may be optional or may be combined.

[0258] Although aspects of the present invention are described in the independent claims, other aspects of the present invention include other combinations of features from the described embodiments and / or dependent claims with the features of the independent claims, rather than only the combinations explicitly described in the claims.

[0259] It is also noted herein that although example embodiments of the present invention are described above, these descriptions should not be considered limiting. Rather, various changes and modifications can be made without departing from the scope of the present invention as defined in the appended claims.

[0260] The following abbreviations that may appear in the specification and / or drawings are defined as follows:

[0261] 5G Fifth Generation

[0262] AF Application Function

[0263] AMF Access and Mobility Management Function

[0264] E-SMLC Evolved Serving Mobile Location Center

[0265] GMLC Gateway Mobile Location Center

[0266] GPSI General Public Subscription Identifier

[0267] eNB (or eNodeB) Evolved Node B (e.g., LTE base station)

[0268] gNB (or gNodeB) 5G / NR base station

[0269] HPLMN Home PLMN

[0270] ID Identification

[0271] I / F Interface

[0272] LMF Location Management Function

[0273] LTE Long Term Evolution

[0274] MBS Multicast / Broadcast Service

[0275] MB-SMF Multicast Broadcast Session Management Function

[0276] MCC Mobile Country Code

[0277] MME Mobility Management Entity

[0278] MNC Mobile Network Code

[0279] NEF Network Exposure Function

[0280] NF Network Function

[0281] Ng or NG Next Generation

[0282] NG-RAN Next Generation RAN

[0283] NR New Radio

[0284] NRF Network Repository Function

[0285] N / W or NW Network

[0286] PLMN Public Land Mobile Network

[0287] RAN Radio Access Network

[0288] Rel Release

[0289] Rx Receiver

[0290] SGW Serving Gateway

[0291] SMF Session Management Function

[0292] SUPI Subscription Permanent Identifier

[0293] TRP Transmitter-Receiver Point

[0294] Tx Transmitter

[0295] UDM Unified Data Management

[0296] UDR Unified Data Repository

[0297] UE User Equipment (e.g., wireless device, typically a mobile device)

[0298] UL Uplink (from UE to network)

[0299] UPF User Plane Function

[0300] VPLMN Visited PLMN

Claims

1. An apparatus comprising components for performing the following operations: storing, at a multicast-broadcast session management function in a visited public land mobile network of a roaming user equipment, for a multicast / broadcast service session, at least one of: information about a roaming user equipment that is authorized to use the multicast / broadcast service session, or corresponding information related to the roaming user equipment about multicast / broadcast service assistance for the multicast / broadcast service session; receiving, by the multicast-broadcast session management function from a session management function in the visited public land mobile network, a request for a context state subscription for the multicast / broadcast service session; as well as The stored information is used by the multicast-broadcast session management function and at least one of the following items is sent in response to the request: one or more identifiers of user equipment authorized to access the multicast / broadcast service session, or information about multicast / broadcast service assistance for the multicast / broadcast service session including identifiers of associated roaming user equipment.

2. An apparatus comprising means for performing the following operations: receiving, by a session management function in a visited public land mobile network of the roaming user equipment from an access and mobility management function in the visited public land mobile network, an indication that the roaming user equipment wants to join a multicast / broadcast service session; sending, by the session management function, a request for information about the multicast / broadcast service session to a multicast-broadcast session management function in the visited public land mobile network; receiving, by the session management function from the multicast-broadcast session management function in the visited public land mobile network, at least one of: one or more identifiers of user equipments authorized to access the multicast / broadcast service session, or information regarding multicast / broadcast service assistance for the multicast / broadcast service session including identifiers of associated roaming user equipments; performing, by the session management function, an authorization check to determine whether the roaming user equipment is authorized to access the multicast / broadcast service session; as well as A response to the indication that the roaming user equipment wants to join the multicast / broadcast service session is sent by the session management function to the access and mobility management function, the response indicating that the user equipment is authorized to join the multicast / broadcast service session.

3. An apparatus comprising means for performing the following operations: receiving, at a network open function, from an application function, a message for creating or modifying a multicast / broadcast service session, the message including an identifier of the multicast / broadcast service session and at least one of: a universal public subscription identifier of a roaming user equipment that is authorized to access the multicast / broadcast service session, or multicast / broadcast service assistance information associated with the roaming user equipment for the multicast / broadcast service session; and The message is forwarded from the network opening function to a multicast broadcast session management function in a visited public land mobile network of the roaming user equipment.

4. An apparatus comprising means for performing the following operations: receiving, at a unified data management in a visited public land mobile network of a roaming user equipment, a request to store information related to a multicast / broadcast service session, the request comprising an identifier of the multicast / broadcast service session and at least one of: one or more identifiers corresponding to one or more user equipments authorized to access the multicast / broadcast service session, and information regarding multicast / broadcast service assistance for the multicast / broadcast service session including identifiers of associated user equipments; determining, by the unified data management, an inbound roaming user equipment from at least one of: the one or more user equipments authorized to access the multicast / broadcast service session, and user equipments associated with the information regarding multicast / broadcast service assistance; as well as A request for storing information related to the multicast / broadcast service session is sent by the unified data management to a multicast-broadcast session management function or a unified data repository, the request including the identifier of the multicast / broadcast service session and at least one of the following items: the identifier corresponding to the determined inbound roaming user equipment that is authorized to access the multicast / broadcast service session, and information about multicast / broadcast service assistance for the multicast / broadcast service session including the identifier of the determined inbound roaming user equipment.

5. An apparatus comprising means for performing the following operations: storing, at a unified data repository in a visited public land mobile network of the roaming user equipment, an identifier of the multicast / broadcast service session and at least one of: one or more identifiers corresponding to one or more roaming user equipments authorized to access the multicast / broadcast service session, or information regarding multicast / broadcast service assistance for the multicast / broadcast service session including identifiers of the relevant roaming user equipments; receiving, by the unified data repository from a session management function in the visited public land mobile network, a request for subscription to the multicast / broadcast service session, the request including a session identifier of the multicast / broadcast service session; as well as The stored information is used by the unified data repository and, in response to the request, at least one of the following items is sent to the session management function: the one or more identifiers of the roaming user devices that are authorized to access the multicast / broadcast service session corresponding to the session identifier, and information about multicast / broadcast service assistance for the multicast / broadcast service session including the identifiers of the relevant roaming user devices.

6. An apparatus comprising means for performing the following operations: receiving, by a session management function in a visited public land mobile network of the roaming user equipment from an access and mobility management function in the visited public land mobile network, an indication that the roaming user equipment wants to join a multicast / broadcast service session; Sending, by the session management function, a request for subscription to information related to the multicast / broadcast service session to a unified data repository in the visited public land mobile network, the request including a session identifier of the multicast / broadcast service session; receiving, by the session management function in response to the request, from a unified data repository in the visited public land mobile network, information comprising at least one of: one or more identifiers of roaming user equipments that are authorized to access the multicast / broadcast service session corresponding to the session identifier, or information regarding multicast / broadcast service assistance for the multicast / broadcast service session including identifiers of relevant roaming user equipments; performing, by the session management function, an authorization check on the roaming user equipment to check whether the roaming user equipment is authorized to access the multicast / broadcast service session; as well as A response to the indication that the roaming user equipment wants to join a multicast / broadcast service session is sent by the session management function to the access and mobility management function, the information for multicast / broadcast service assistance indicating that the user equipment is authorized to join the multicast / broadcast service session.

7. An apparatus comprising means for performing the following operations: receiving, at a unified data management in a home public land mobile network of a roaming user equipment, a request to store information related to a multicast / broadcast service session from a network opening function in the home public land mobile network or a unified data management in a visited public land mobile network, the request comprising an identifier of the multicast / broadcast service session and at least one of the following: a universal public subscription identifier of a roaming user equipment authorized to access the multicast / broadcast service session, information for multicast / broadcast service assistance, the information comprising a universal public subscription identifier of the relevant roaming user equipment, an identifier of the visited public land mobile network, and a service class; checking, by the unified data management for a separately received universal public subscription identifier for a roaming user equipment, whether the roaming user equipment is authorized to access the multicast / broadcast service of the multicast / broadcast service session using at least one of: a received visited public land mobile network identification, a received service class, stored information on whether the user equipment is authorized to receive multicast / broadcast services when roaming, stored information on visited public land mobile networks from which the user equipment is authorized to receive multicast / broadcast services when roaming, or stored information on service classes of multicast / broadcast services that the user equipment is authorized to receive when roaming; and The unified data management stores at least one of the following items for individual roaming user equipment among those roaming user equipment that are authorized to receive the multicast / broadcast service in the visited public land mobile network: the identifier of the authorized multicast / broadcast service session corresponding to the multicast / broadcast service, or multicast / broadcast service assistance information for the multicast / broadcast service session.

8. An apparatus comprising means for performing the following operations: identifying, at an application function in a public land mobile network providing data for a multicast / broadcast service session, a user equipment having a different public land mobile network as a home public land mobile network and the home public land mobile network of the user equipment that is authorized to participate in the multicast / broadcast service session; and A request for providing data for the multicast / broadcast service session is sent from the application function to a network open function in the home public land mobile network, the request comprising at least one of: an identifier of the multicast / broadcast service session, and at least one of: a universal public subscription identifier of a roaming user equipment from the home public land mobile network that is authorized to access the multicast / broadcast service session, information for multicast / broadcast service assistance including a universal public subscription identifier of relevant roaming user equipment from the home public land mobile network, a public land mobile network identifier of the public land mobile network providing the multicast / broadcast service session, and a service class.

9. An apparatus comprising means for performing the following operations: receiving, at a unified data management in a public land mobile network providing a multicast / broadcast service session, from a network openness function in the public land mobile network, a request for providing data for the multicast / broadcast service session, the request comprising at least one of: an identification of the multicast / broadcast service session, and at least one of: a universal public subscription identifier of a user equipment authorized to access the multicast / broadcast service session, information for multicast / broadcast service assistance including the universal public subscription identifier of the associated user equipment, or a service class; identifying, at the unified data management, a universal public subscription identifier of a user equipment having a different public land mobile network as a home public land mobile network and the home public land mobile network of the user equipment; and A request for providing data for the multicast / broadcast service session is sent from the unified data management in the public land mobile network to the unified data management in the home public land mobile network, the request including an identifier of the multicast / broadcast service session and at least one of the following items: a universal public subscription identifier of a roaming user equipment from the home public land mobile network that is authorized to access the multicast / broadcast service session, information for multicast / broadcast service assistance including a universal public subscription identifier of relevant roaming user equipment from the home public land mobile network, a public land mobile network identifier of the public land mobile network providing the multicast / broadcast service session, or a service class.

10. An apparatus comprising means for performing the following operations: receiving, at a unified data management in a public land mobile network providing a multicast / broadcast service session, from a network openness function in the public land mobile network, a request for providing data for the multicast / broadcast service session, the request comprising at least one of: an identification of the multicast / broadcast service session, and at least one of: a universal public subscription identifier of a user equipment authorized to access the multicast / broadcast service session, or information for multicast / broadcast service assistance comprising a universal public subscription identifier of an associated user equipment; identifying, at the unified data management, a universal public subscription identifier of a user equipment having a different public land mobile network as a home public land mobile network and the home public land mobile network of the user equipment; for the individual identified user equipment, sending, from the unified data management in the public land mobile network to the unified data management in the home public land mobile network of the identified user equipment, a request for provision of an identifier for handling a session management function for the identified user equipment, the request including the universal public subscription identifier of the identified user equipment; receiving, for the individual identified user equipment, at the unified data management in the public land mobile network, a response from the unified data management in the home public land mobile network of the identified user equipment, the response comprising at least one identifier of a session management function handling the identified user equipment and a subscription permanent identifier of the identified user equipment; and For a single identified user equipment, a request for providing data for the multicast / broadcast service session is sent from the unified data management in the public land mobile network to the session management function, the request comprising an identifier of the multicast / broadcast service session and at least one of: the subscription permanent identifier of the identified roaming user equipment indicating that the identified roaming user equipment is authorized to access the multicast / broadcast service session, or information for multicast / broadcast service assistance comprising the subscription permanent identifier of the identified roaming user equipment.

11. An apparatus comprising means for performing the following operations: receiving, by a session management function in a visited public land mobile network of a roaming user equipment, from a unified data management in the visited public land mobile network, a request for providing data for a multicast / broadcast service session, the request comprising an identification of the multicast / broadcast service session and at least one of: a subscription permanent identifier of the roaming user equipment indicating that the roaming user equipment is authorized to access the multicast / broadcast service session, and information for multicast / broadcast service assistance comprising the subscription permanent identifier of the roaming user equipment; storing, by the session management function, the received identification of the multicast / broadcast service session and at least one of: a received subscription permanent identifier of a roaming user equipment indicating that the roaming user equipment is authorized to access the multicast / broadcast service session, or the received information for multicast / broadcast service assistance including the subscription permanent identifier of the roaming user equipment; receiving, by the session management function from an access and mobility management function in the visited public land mobile network, an indication that a roaming user equipment desires to join the multicast / broadcast service session; performing, by the session management function, an authorization check to determine whether the roaming user equipment is authorized to access the multicast / broadcast service session; as well as A response to the indication that the roaming user equipment wants to join the multicast / broadcast service session is sent by the session management function to the access and mobility management function, the response indicating that the user equipment is authorized to join the multicast / broadcast service session.

12. A device according to any preceding device claim, wherein: The components include: at least one processor; and At least one memory storing instructions that, when executed by the at least one processor, result in the performance of the apparatus.

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