Per-UE authorization in VPLMN for MBS

Abstract

An apparatus, comprising means for performing: storing, at a multicast broadcast session management function, MB-SMF, in a visiting public land mobile network, VPLMN, for roaming user equipment, UE, i

Description

TECHNICAL FIELD

[0001] Examples of embodiments herein relate generally to cellular communication systems and, more specifically, relate to servicing multicast MBS (Multicast / Broadcast Services) when a UE (user equipment) is in a visiting public land mobile network (VPLMN). BACKGROUND

[0002] Multicast / Broadcast Services (MBS) in a cellular network considers both broadcast and multicast. A broadcast communication service is where data is transmitted to all users in a broadcast service area. Meanwhile, in a multicast communication service, data are transmitted to a dedicated set of users (i.e., not all users within coverage of the multicast service are authorized to receive the data). MBS multicast services are able to operate no matter where a UE (user equipment, a wireless device that connects to the cellular network) is in a public land mobile network, and data are transmitted where a UE related to any users out of the dedicated set of authorized users is located. However, reception of MBS multicast services is so far restricted to UEs in their “home” public land mobile network (HPLMN) and services offered by that HPLMN. It would be desirable to also enable reception of MBS multicast services offered in a “visited” PLMN (VPLMN) to UEs roaming into that VPLMN.

[0003] For instance, a UE starts in a “home” public land mobile network (HPLMN), which is the network of the subscriber's home operator. A PLMN for an operator can be thought of as a core network of entities and a radio access network (RAN), which allows the UE to connect to the core network. Once the subscriber with the UE is roaming outside the HPLMN and in another PLMN, this becomes a “visiting” PLMN. MBS is supposed to operate seamlessly between both PLMNs, but there can be issues that occur when a UE roams into a VPLMN and multicast MBS is being used. BRIEF SUMMARY

[0004] This section is intended to include examples and is not intended to be limiting.

[0005] In an exemplary embodiment, a method is disclosed that includes storing, at an MB-SMF in a VPLMN for roaming UEs, in relation to an MBS session, at least one of information about roaming UEs authorized to use the MBS session or corresponding information about MBS assistance for the MBS session related to the roaming UEs; receiving, by the MB-SMF from an SMF in the VPLMN, a request for a context status subscribe for the MBS session; and sending, by the MB-SMF using the stored information and in response to the request, 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 comprising identifiers of related roaming UEs.

[0006] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[0007] 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 at least to perform: storing, at an MB-SMF in a VPLMN for roaming UEs, in relation to an MBS session, at least one of information about roaming UEs authorized to use the MBS session or corresponding information about MBS assistance for the MBS session related to the roaming UEs; receiving, by the MB-SMF from an SMF in the VPLMN, a request for a context status subscribe for the MBS session; and sending, by the MB-SMF using the stored information and in response to the request, 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 comprising identifiers of related roaming UEs.

[0008] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: storing, at an MB-SMF in a VPLMN for roaming UEs, in relation to an MBS session, at least one of information about roaming UEs authorized to use the MBS session or corresponding information about MBS assistance for the MBS session related to the roaming UEs; receiving, by the MB-SMF from an SMF in the VPLMN, a request for a context status subscribe for the MBS session; and sending, by the MB-SMF using the stored information and in response to the request, 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 comprising identifiers of related roaming UEs.

[0009] In another exemplary embodiment, an apparatus comprises means for performing: storing, at an MB-SMF in a VPLMN for roaming UEs, in relation to an MBS session, at least one of information about roaming UEs authorized to use the MBS session or corresponding information about MBS assistance for the MBS session related to the roaming UEs; receiving, by the MB-SMF from an SMF in the VPLMN, a request for a context status subscribe for the MBS session; and sending, by the MB-SMF using the stored information and in response to the request, 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 comprising identifiers of related roaming UEs.

[0010] In an exemplary embodiment, a method is disclosed that includes receiving, by an SMF in a VPLMN for roaming UEs from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to an MB-SMF in the VPLMN, a request for information about the MBS session; 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 comprising identifiers of related roaming UEs; 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 indicating the UE is authorized to join the MBS session.

[0011] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[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 at least to perform: receiving, by an SMF in a VPLMN for roaming UEs from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to an MB-SMF in the VPLMN, a request for information about the MBS session; 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 comprising identifiers of related roaming UEs; 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 indicating the UE is authorized to join the MBS session.

[0013] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, by an SMF in a VPLMN for roaming UEs from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to an MB-SMF in the VPLMN, a request for information about the MBS session; 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 comprising identifiers of related roaming UEs; 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 indicating the UE is authorized to join the MBS session.

[0014] In another exemplary embodiment, an apparatus comprises means for performing: receiving, by an SMF in a VPLMN for roaming UEs from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to an MB-SMF in the VPLMN, a request for information about the MBS session; 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 comprising identifiers of related roaming UEs; 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 indicating the UE is authorized to join the MBS session.

[0015] In an exemplary embodiment, a method is disclosed that includes receiving, at an NEF from an AF, a message to create or modify an MBS session, comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access an MBS session, or information for MBS assistance for the MBS session related to roaming UEs; and forwarding, from the NEF to an MB-SMF in a VPLMN of the roaming UEs, the message.

[0016] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[0017] 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 at least to perform: receiving, at an NEF from an AF, a message to create or modify an MBS session, comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access an MBS session, or information for MBS assistance for the MBS session related to roaming UEs; and forwarding, from the NEF to an MB-SMF in a VPLMN of the roaming UEs, the message.

[0018] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, at an NEF from an AF, a message to create or modify an MBS session, comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access an MBS session, or information for MBS assistance for the MBS session related to roaming UEs; and forwarding, from the NEF to an MB-SMF in a VPLMN of the roaming UEs, the message.

[0019] In another exemplary embodiment, an apparatus comprises means for performing: receiving, at an NEF from an AF, a message to create or modify an MBS session, comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access an MBS session, or information for MBS assistance for the MBS session related to roaming UEs; and forwarding, from the NEF to an MB-SMF in a VPLMN of the roaming UEs, the message.

[0020] In an exemplary embodiment, a method is disclosed that includes receiving, at a UDM in a VPLMN of roaming UEs, a request to store information related to an MBS session comprising an identifier of the MBS session and at least one of 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 comprising identifiers of related UEs; determining, by the UDM, inbound roaming UEs out of at least one of the one or more UEs authorized to access the MBS session and the UEs 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 UDR, the request comprising the identifier of the MBS session and at least one of the identifiers corresponding to the determined inbound roaming UEs authorized to access the MBS session, and information about MBS assistance for the MBS session comprising identifiers of the determined inbound roaming UEs.

[0021] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[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 at least to perform: receiving, at a UDM in a VPLMN of roaming UEs, a request to store information related to an MBS session comprising an identifier of the MBS session and at least one of 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 comprising identifiers of related UEs; determining, by the UDM, inbound roaming UEs out of at least one of the one or more UEs authorized to access the MBS session and the UEs 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 UDR, the request comprising the identifier of the MBS session and at least one of the identifiers corresponding to the determined inbound roaming UEs authorized to access the MBS session, and information about MBS assistance for the MBS session comprising identifiers of the determined inbound roaming UEs.

[0023] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, at a UDM in a VPLMN of roaming UEs, a request to store information related to an MBS session comprising an identifier of the MBS session and at least one of 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 comprising identifiers of related UEs; determining, by the UDM, inbound roaming UEs out of at least one of the one or more UEs authorized to access the MBS session and the UEs 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 UDR, the request comprising the identifier of the MBS session and at least one of the identifiers corresponding to the determined inbound roaming UEs authorized to access the MBS session, and information about MBS assistance for the MBS session comprising identifiers of the determined inbound roaming UEs.

[0024] In another exemplary embodiment, an apparatus comprises means for performing: receiving, at a UDM in a VPLMN of roaming UEs, a request to store information related to an MBS session comprising an identifier of the MBS session and at least one of 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 comprising identifiers of related UEs; determining, by the UDM, inbound roaming UEs out of at least one of the one or more UEs authorized to access the MBS session and the UEs 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 UDR, the request comprising the identifier of the MBS session and at least one of the identifiers corresponding to the determined inbound roaming UEs authorized to access the MBS session, and information about MBS assistance for the MBS session comprising identifiers of the determined inbound roaming UEs.

[0025] In an exemplary embodiment, a method is disclosed that includes storing, at a UDR in a VPLMN of roaming UEs, an identifier of an MBS session and at least one of 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 comprising identifiers of related roaming UEs; receiving, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session and comprising a session ID for the MBS session; and sending, by the UDR to the SMF using the stored information and in response to the request, at least one of 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 comprising the identifiers of the related roaming UEs.

[0026] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[0027] 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 at least to perform: storing, at a UDR in a VPLMN of roaming UEs, an identifier of an MBS session and at least one of 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 comprising identifiers of related roaming UEs; receiving, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session and comprising a session ID for the MBS session; and sending, by the UDR to the SMF using the stored information and in response to the request, at least one of 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 comprising the identifiers of the related roaming UEs.

[0028] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: storing, at a UDR in a VPLMN of roaming UEs, an identifier of an MBS session and at least one of 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 comprising identifiers of related roaming UEs; receiving, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session and comprising a session ID for the MBS session; and sending, by the UDR to the SMF using the stored information and in response to the request, at least one of 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 comprising the identifiers of the related roaming UEs.

[0029] In another exemplary embodiment, an apparatus comprises means for performing: storing, at a UDR in a VPLMN of roaming UEs, an identifier of an MBS session and at least one of 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 comprising identifiers of related roaming UEs; receiving, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session and comprising a session ID for the MBS session; and sending, by the UDR to the SMF using the stored information and in response to the request, at least one of 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 comprising the identifiers of the related roaming UEs.

[0030] In an exemplary embodiment, a method is disclosed that includes receiving, by an SMF in a VPLMN of roaming UEs and from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to a UDR in the VPLMN, a request for a subscription for information related to the MBS session and comprising a session ID for the MBS session; receiving, by the SMF and from a UDR in the VPLMN and in response to the request, information comprising 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 comprising identifiers of related 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 to the AMF, a response to the indication that a roaming UE wants to join an MBS session, information for MBS assistance indicating the UE is authorized to join the MBS session.

[0031] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[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 at least to perform: receiving, by an SMF in a VPLMN of roaming UEs and from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to a UDR in the VPLMN, a request for a subscription for information related to the MBS session and comprising a session ID for the MBS session; receiving, by the SMF and from a UDR in the VPLMN and in response to the request, information comprising 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 comprising identifiers of related 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 to the AMF, a response to the indication that a roaming UE wants to join an MBS session, information for MBS assistance indicating the UE is authorized to join the MBS session.

[0033] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, by an SMF in a VPLMN of roaming UEs and from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to a UDR in the VPLMN, a request for a subscription for information related to the MBS session and comprising a session ID for the MBS session; receiving, by the SMF and from a UDR in the VPLMN and in response to the request, information comprising 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 comprising identifiers of related 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 to the AMF, a response to the indication that a roaming UE wants to join an MBS session, information for MBS assistance indicating the UE is authorized to join the MBS session.

[0034] In another exemplary embodiment, an apparatus comprises means for performing: receiving, by an SMF in a VPLMN of roaming UEs and from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to a UDR in the VPLMN, a request for a subscription for information related to the MBS session and comprising a session ID for the MBS session; receiving, by the SMF and from a UDR in the VPLMN and in response to the request, information comprising 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 comprising identifiers of related 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 to the AMF, a response to the indication that a roaming UE wants to join an MBS session, information for MBS assistance indicating the UE is authorized to join the MBS session.

[0035] In an exemplary embodiment, a method is disclosed that includes receiving, at a UDM in an HPLMN for roaming UEs from an NEF in the HPLMN or an UDM in an VPLMN, a request for storing information related to an MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs, a VPLMN ID, and a service class; checking, by the UDM for individual received Generic Public Subscription Identifiers of a roaming UE, whether that roaming UE is authorized to access an MBS service for the MBS session using at least one of the received VPLMN ID, the received service class, stored information whether the UE is entitled to receive MBS services when roaming, stored information about VPLMNs from which the UE is entitled to receive MBS services when roaming, or stored information about service classes of MBS services that the UE is entitled to receive when roaming; and storing, by the UDM for individual ones of those roaming UEs that are authorized to receive the MBS service m the VPLMN, at least one of the identification of an authorized MBS session corresponding to the MBS service or information for MBS assistance for the MBS session.

[0036] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[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 at least to perform: receiving, at a UDM in an HPLMN for roaming UEs from an NEF in the HPLMN or an UDM in an VPLMN, a request for storing information related to an MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs, a VPLMN ID, and a service class; checking, by the UDM for individual received Generic Public Subscription Identifiers of a roaming UE, whether that roaming UE is authorized to access an MBS service for the MBS session using at least one of the received VPLMN ID, the received service class, stored information whether the UE is entitled to receive MBS services when roaming, stored information about VPLMNs from which the UE is entitled to receive MBS services when roaming, or stored information about service classes of MBS services that the UE is entitled to receive when roaming; and storing, by the UDM for individual ones of those roaming UEs that are authorized to receive the MBS service in the VPLMN, at least one of the identification of an authorized MBS session corresponding to the MBS service or information for MBS assistance for the MBS session.

[0038] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, at a UDM in an HPLMN for roaming UEs from an NEF in the HPLMN or an UDM in an VPLMN, a request for storing information related to an MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs, a VPLMN ID, and a service class; checking, by the UDM for individual received Generic Public Subscription Identifiers of a roaming UE, whether that roaming UE is authorized to access an MBS service for the MBS session using at least one of the received VPLMN ID, the received service class, stored information whether the UE is entitled to receive MBS services when roaming, stored information about VPLMNs from which the UE is entitled to receive MBS services when roaming, or stored information about service classes of MBS services that the UE is entitled to receive when roaming; and storing, by the UDM for individual ones of those roaming UEs that are authorized to receive the MBS service in the VPLMN, at least one of the identification of an authorized MBS session corresponding to the MBS service or information for MBS assistance for the MBS session.

[0039] In another exemplary embodiment, an apparatus comprises means for performing: receiving, at a UDM in an HPLMN for roaming UEs from an NEF in the HPLMN or an UDM in an VPLMN, a request for storing information related to an MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs, a VPLMN ID, and a service class; checking, by the UDM for individual received Generic Public Subscription Identifiers of a roaming UE, whether that roaming UE is authorized to access an MBS service for the MBS session using at least one of the received VPLMN ID, the received service class, stored information whether the UE is entitled to receive MBS services when roaming, stored information about VPLMNs from which the UE is entitled to receive MBS services when roaming, or stored information about service classes of MBS services that the UE is entitled to receive when roaming; and storing, by the UDM for individual ones of those roaming UEs that are authorized to receive the MBS service in the VPLMN, at least one of the identification of an authorized MBS session corresponding to the MBS service or information for MBS assistance for the MBS session.

[0040] In an exemplary embodiment, a method is disclosed that includes identifying, at an AF providing data for an MBS session in a PLMN, UEs authorized to participate in the MBS session that have a different PLMN as HPLMN and their HPLMN; and sending, from the AF towards an NEF in the HPLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, and a service class.

[0041] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[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 at least to perform: identifying, at an AF providing data for an MBS session in a PLMN, UEs authorized to participate in the MBS session that have a different PLMN as HPLMN and their HPLMN; and sending, from the AF towards an NEF in the HPLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, and a service class.

[0043] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: identifying, at an AF providing data for an MBS session in a PLMN, UEs authorized to participate in the MBS session that have a different PLMN as HPLMN and their HPLMN; and sending, from the AF towards an NEF in the HPLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, and a service class.

[0044] In another exemplary embodiment, an apparatus comprises means for performing: identifying, at an AF providing data for an MBS session in a PLMN, UEs authorized to participate in the MBS session that have a different PLMN as HPLMN and their HPLMN; and sending, from the AF towards an NEF in the HPLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, and a service class.

[0045] In an exemplary embodiment, a method is disclosed that includes receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs, or a service class; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; and sending, from the UDM in the PLMN towards a UDM in the HPLMN a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, or a service class.

[0046] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[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 at least to perform: receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs, or a service class; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; and sending, from the UDM in the PLMN towards a UDM in the HPLMN a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, or a service class.

[0048] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs, or a service class; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; and sending, from the UDM in the PLMN towards a UDM in the HPLMN a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, or a service class.

[0049] In another exemplary embodiment, an apparatus comprises means for performing: receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs, or a service class; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; and sending, from the UDM in the PLMN towards a UDM in the HPLMN a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, or a service class.

[0050] In an exemplary embodiment, a method is disclosed that includes receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN, a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, or information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; sending, for individual identified UEs, from the UDM in the PLMN towards a UDM in the HPLMN of the identified UE, a request to provision identifiers of SMFs handling the identified UE, the request comprising the Generic Public Subscription Identifiers of the identified UE; receiving, for individual identified UEs, at the UDM in the PLMN from the UDM in the HPLMN of the identified UE, a response comprising at least one identifier of an SMF handling the identified UE and a Subscription Permanent Identifier of the identified UE; and sending, for individual identified UEs, from the UDM in the PLMN towards the SMF, a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of the Subscription Permanent Identifier of the identified roaming UE to indicate that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance comprising Subscription Permanent Identifier of the identified roaming UE.

[0051] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[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 at least to perform: receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN, a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, or information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; sending, for individual identified UEs, from the UDM in the PLMN towards a UDM in the HPLMN of the identified UE, a request to provision identifiers of SMFs handling the identified UE, the request comprising the Generic Public Subscription Identifiers of the identified UE; receiving, for individual identified UEs, at the UDM in the PLMN from the UDM in the HPLMN of the identified UE, a response comprising at least one identifier of an SMF handling the identified UE and a Subscription Permanent Identifier of the identified UE; and sending, for individual identified UEs, from the UDM in the PLMN towards the SMF, a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of the Subscription Permanent Identifier of the identified roaming UE to indicate that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance comprising Subscription Permanent Identifier of the identified roaming UE.

[0053] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN, a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, or information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; sending, for individual identified UEs, from the UDM in the PLMN towards a UDM in the HPLMN of the identified UE, a request to provision identifiers of SMFs handling the identified UE, the request comprising the Generic Public Subscription Identifiers of the identified UE; receiving, for individual identified UEs, at the UDM in the PLMN from the UDM in the HPLMN of the identified UE, a response comprising at least one identifier of an SMF handling the identified UE and a Subscription Permanent Identifier of the identified UE; and sending, for individual identified UEs, from the UDM in the PLMN towards the SMF, a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of the Subscription Permanent Identifier of the identified roaming UE to indicate that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance comprising Subscription Permanent Identifier of the identified roaming UE.

[0054] In another exemplary embodiment, an apparatus comprises means for performing: receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN, a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, or information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; sending, for individual identified UEs, from the UDM in the PLMN towards a UDM in the HPLMN of the identified UE, a request to provision identifiers of SMFs handling the identified UE, the request comprising the Generic Public Subscription Identifiers of the identified UE; receiving, for individual identified UEs, at the UDM in the PLMN from the UDM in the HPLMN of the identified UE, a response comprising at least one identifier of an SMF handling the identified UE and a Subscription Permanent Identifier of the identified UE; and sending, for individual identified UEs, from the UDM in the PLMN towards the SMF, a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of the Subscription Permanent Identifier of the identified roaming UE to indicate that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance comprising Subscription Permanent Identifier of the identified roaming UE.

[0055] In an exemplary embodiment, a method is disclosed that includes receiving, by an SMF in an VPLMN of roaming UEs from a UDM in the VPLMN, a request to provision data for an MBS session, the request comprising an identification of the MBS session, and at least one of a Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, and information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; storing, by the SMF the received identification of the MBS session, and at least one of the received Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, or the received information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; receiving, by the SMF from an AMF in the VPLMN, an indication that a 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 indicating the UE is authorized to join the MBS session.

[0056] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[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 at least to perform: receiving, by an SMF in an VPLMN of roaming UEs from a UDM in the VPLMN, a request to provision data for an MBS session, the request comprising an identification of the MBS session, and at least one of a Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, and information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; storing, by the SMF the received identification of the MBS session, and at least one of the received Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, or the received information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; receiving, by the SMF from an A MF in the VPLMN, an indication that a 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 indicating the UE is authorized to join the MBS session.

[0058] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, by an SMF in an VPLMN of roaming UEs from a UDM in the VPLMN, a request to provision data for an MBS session, the request comprising an identification of the MBS session, and at least one of a Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, and information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; storing, by the SMF the received identification of the MBS session, and at least one of the received Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, or the received information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; receiving, by the SMF from an AMF in the VPLMN, an indication that a 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 indicating the UE is authorized to join the MBS session.

[0059] In another exemplary embodiment, an apparatus comprises means for performing: receiving, by an SMF in an VPLMN of roaming UEs from a UDM in the VPLMN, a request to provision data for an MBS session, the request comprising an identification of the MBS session, and at least one of a Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, and information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; storing, by the SMF the received identification of the MBS session, and at least one of the received Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, or the received information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; receiving, by the SMF from an AMF in the VPLMN, an indication that a 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 indicating the UE is authorized to join the MBS session. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In the attached drawings:

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

[0062] FIG. 1A is a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced;

[0063] FIG. 2 is an example of a signaling diagram illustrating a first technique (Technique 1) and a first embodiment (Embodiment 1) for that technique;

[0064] FIG. 3 is an example of a signaling diagram illustrating a first technique (Technique 1) and a second embodiment (Embodiment 2) for that technique;

[0065] FIG. 4 is an example of a signaling diagram illustrating a second technique (Technique 2);

[0066] FIG. 4A is a flow diagram helping explain some of the operations and signaling in FIGS. 3 and 4;

[0067] FIG. 5 is an example of a signaling diagram illustrating a third technique (Technique 3) and a first embodiment (Embodiment 1) for that technique;

[0068] FIG. 6 is an example of a signaling diagram illustrating a third technique (Technique 3) and a second embodiment (Embodiment 2) for that technique;

[0069] FIG. 6A is a flow diagram helping explain a check for a roaming UE in FIGS. 5 and 6;

[0070] FIG. 7 is an example of a signaling diagram illustrating a fourth technique (Technique 4);

[0071] FIGS. 8, 9, and 10 are flow diagrams illustrating corresponding parts of Technique 1 at the MB-SMF, the SMF, and the NEF respectively;

[0072] FIG. 11 is a flow diagram of operations of the UDM as applied to FIGS. 3 and 4;

[0073] FIG. 12 is a flow diagram of operations of the U DR as applied at least to FIG. 4;

[0074] FIG. 13 is a flow diagram of operations of the SAIF as applied at least to FIG. 4;

[0075] FIG. 14 is a flow diagram of operations of the UDM as applied at least to FIGS. 5 and 6;

[0076] FIG. 15 is a flow diagram of operations of the AF as applied at least to FIG. 5;

[0077] FIG. 16 is a flow diagram of operations of the UDM as applied at least to FIG. 5;

[0078] FIG. 17 is a flow diagram of operations of the UDNI as applied at least to FIG. 5; and

[0079] FIG. 18 is a flow diagram of operations of the SMF as applied at least to FIG. 7. DETAILED DESCRIPTION OF THE DRAWINGS

[0080] Abbreviations that may be found in the specification and / or the drawing figures are defined below, at the end of the detailed description 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 of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention which is defined by the claims.

[0082] When more than one drawing reference numeral, word, or acronym is used within this description with “ / ”, and in general as used within this description, the “ / ” may be interpreted as “or”, “and”, or “both”. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or,” mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[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 be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, 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 flow diagram or signaling diagram (FIGS. 2-7, including 4A) herein is considered to be a logic flow diagram, and illustrates the operation of an exemplary method, results of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and / or interconnected means for performing functions in accordance with an exemplary embodiment. Block diagrams (such as FIG. 1 and FIG. 1 A) also illustrate the operation of an exemplary method, results of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and / or interconnected means for performing functions in accordance with an exemplary embodiment. For methods, flow diagrams, and signaling diagrams, the orders of method steps, blocks in the flow, or signaling are not critical and instead are examples.

[0085] Before proceeding with examples of embodiments, introduction is provided to technology areas related to the embodiments. One such area is 5G.

[0086] 5G system enhancements using NR to support multicast and broadcast communication services (MBS) have been standardized by 3GPP In 3GGP TS 23.247 (see, e.g., 3GPP TS 23.247 V18.3.0 (2023-09), Architectural enhancements for 5G multicast-broadcast services, Stage 2 (Release 18)). An MBS multicast session may be open to “any UE” which is entitled to use MBS multicast services, or only to specific UEs as provisioned by the AF that also creates the MBS multicast session.

[0087] While there are stage 1 requirements related to roaming, roaming is not yet supported for MBS: This is illustrated by this text from 3GPP TS 22.246: 5.1 Common requirements to broadcast and multicast In case of roaming a user shall be able to enjoy services as follows: • A user shall be able to activate services that are provided locally in the visited network, as allowed by the user’s home environment (e.g., local tourist information).

[0088] According to existing standards, both the MBS Session Authorization information and the MBS Session assistance information are provisioned by the AF to the NEF via the NEF parameter provisioning procedure and stored by the NEF in the UDM. Certain relevant parts of the 3GPP specifications are outlined below.

[0089] In 3GPP TS 23.247 (see, e g., 3GPP TS 23.247, Architecture enhancements for 5G System (5GS) to support network data analytics services (Release 18)), this states the following: 6.4.2 MBS subscription data in UDM The information stored in the UDM as defined in clause 5.2.3.3.1 of TS 23.502 [6] is extended as follows: MBS subscription data for a UE as part of UE subscription data, as defined in Table 6.4.2-1, with keys defined in Table 6.4.2-2. 5

[0090] This is further described by Table 6.4.2-1: MBS subscription data type, which is shown below: Subscription data type Field Description MBS subscription data MBS allowed Indicates whether the UE is authorized to use the multicast MBS service. Allowed MBS Session ID(s) Identifies the MBS Session(s) that the UE are allowed to join. MBS assistance information Indicates that the UE is preferred to be kept connected when the related MBS session the UE joined is active, which contains the related MBS Session ID(s)

[0091] Table 6.4.2-2 describes MBS subscription data type keys and is shown below: Subscription Data Types Data Key Data Su b Key MBS Subscription data SUPI -

[0092] Another section of interest is the following: 6.4.3 MBS information in UDR The MBS information may be stored in the UDR by the UDM as part of the subscription data, as defined in clause 5.2.12.2.1 of TS 23.502 [6], 1. MBS data as defined in Tables 6.4.2-1, with keys defined in Table 6.4.3-1.

[0093] The above section relates to Table 6.4.3-1, MBS data type keys, which is shown below: Data Set Data Subset Data Key Data Sub Key Subscription Data MBS subscription data SUPI - 15

[0094] An additional section of interest is as follows: 7.2.9 AF provisioning multicast MBS Session Authorization information The AF provisions the multicast MBS session authorization information for multicast MBS sessions that are not open to "any UE". The procedure specified in clause 4.15.6.2 of TS 23.502 [6] is reused with the following enhancements: The AF may provision the MBS Session Authorization information to the 5GC. The MBS Session Authorization information is associated with a group ofUEs. The AF may support multicast MBS group membership management and provide parameters as described in Table 7.2.9-2. If a new multicast MBS group is created, the UDM shall assign a unique Internal Group ID for the multicast MBS group and include the newly assigned Internal Group ID in the Nudr DM Create Request message. If the AF is authorised by the UDM to provision the MBS Session Authorization information, the UDM resolves the GPSI of each MBS session group member to SUPI, and requests to create, update or delete the provisioned MBS Session Authorization information as part of the MBS subscription data for each SUPI via Nudr DM Create Update Delete Request message, and the message includes the provisioned MBS Session Authorization information.

[0095] The following table is of interest, Table 7.2.9-1: MBS Session Authorization information: Parameters Description MBS Session Authorization information One or more MBS Session IDs. A group ofUEs identified by an External Group ID.

[0096] 7.2.9-2: Multicast MBS group membership management parameters is illustrated below: Parameters Description List of GPSI List of multicast group members, each member is identified by GPSI. External Group ID Identifier for multicast MBS group.

[0097] Another section that is relevant is the following: 7.2.9a AF provisioning MBS Session assistance information After the AF obtains the MBS Session ID of a multicast MBS Session as specified in clauses 7.1.1.2 and 7.1.1.3, the AF may provision the MBS Session assistance information for the UE(s) via NEF to UDM using the procedure of external parameter provisioning as specified clause 4.15.6.2 of TS 23.502 [6] with the following enhancements: the AF may provision MBS Session Assistance Information, which indicates that a UE is preferred to be kept connected when the related MBS Session the UE joined is active. NOTE 1: MBS Session Assistance information has no effect if the function of UE receiving MBS multicast in RRC INACTIVE state is not used. The AF does not provision the MBS Session assistance information if the AF' knows that the P! MN does not support the function of UE receiving MBS multicast in RRC_ INA CTIVE state. NOTE 2: The AF can provide the MBS Session assistance information for the UEs based on observed or expected UE data transmission behaviour,, e.g., a frequent talker and / or the group leader of a multicast group represented by an MBS Session ID. NOTE 3: If the MBS Assistance Information is already available when a UE joins a multicast MBS Session, the SMF provides the information to the NG-RAN in the UE join procedure as specified in clause 7.2.1.3. If the MBS Assistance Information becomes available in the UDM, the UDM performs procedure of Session Management Subscriber Data Update Notification to SMF as specified in clause 4.5.2 ofTS 23.502 [6]per subscription data change notification requested by the SMF.

[0098] Table 7.2.9a-1: MBS Session Assistance information is illustrated below: Parameters Description MBS Session Assistance information A list of UEs represented by GPSIs that are preferred to be kept connected when the MBS Session represented by the indicated MBS session ID the UE joined is active.

[0099] 3GPP TS 23.288 also states the following: If the AF is authorised by the UDM to provision the UE list MBS Assistance information, the UDM resolves the GPSI to SUPI, and requests to create, update or delete the provisioned UE list MBS Assistance information as part of the MBS subscription data for each SUPI.

[00100] Another topic of interest concerns 3GPP TS 23.502 (see, e g., 3GPP TS 23.502 V18.3.0 (2023-09), Procedures for the 5G System (5GS), Stage 2 (Release 18)). In figure 4.15.6.2, the NEF service operations information flow is described.

[00101] In 3GPP TS 23.247 a signaling diagram is described in 7.1.1.2, MBS Session Creation without PCC. The steps in the figure are also described. Part of section 7.2.1.2 is repeated below: 7.2.1.2 Establishment of a PDU Session that can be associated with multicast session(s) The PDU Session associated with Multicast MBS session(s) (, i.e., the associated PDU Session) is established using the procedures as specified in TS 23.502 [6] clause 4.3.2.2 with the following differences: NOTE 1: The DNN and S-NSSAI are used to establish the PDU session which can carry the operations related to Multicast MBS session(s),, i.e., session join / 1 eave, and can be associated with multicast MBS session(s). In step 2, the AMF selects an SMF capable of handling Multicast MBS sessions based on DNN and S-NSSAI, locally configured data or a corresponding SMF profile stored in the NRF. For indirect discovery, the AMF requests the SCP to select an SMF capable of handling Multicast MBS sessions. In step 4, if MBS subscription data for the UE (, i.e., corresponding SUPI), DNN and S-NSSAI of the HPLMN or subscribed SNPN is not available, the SMF retrieves the MBS subscription data using Nudm SDM Get (SUPI, MBS subscription data, selected DNN, S-NSSAI of the HPLMN or subscribed SNPN, Serving PLMN ID (or PLMN ID and NID)) and subscribes to be notified when this subscription data is modified using Nudm SDM Subscribe (SUPI, MBS subscription data, selected DNN, S-NSSAI of the HPLMN or SNPN, Serving PLMN ID (or PLMN ID and NID)). UDM may get this information from UDR by NudrD (SUPI, MBS data, selected DNN, S-NSSAI of the HPLMN or subscribed SNPN, Serving PLMN ID (or PLMN ID and NID)) and may subscribe to notifications from UDR for the same data by Nudr DM subscribe. The MBS subscription data can also be retrieved along with the Session Management Subscription data,, i.e., with additional input parameter for MBS subscription data in the Nudm SDM services. NOTE 2: In this release, roaming is not supported,, i.e., HPLMN and Serving PLMN are the same and subscribed SNPN and serving SNPN are same.

[00102] Section 7.2.1.3 describes multicast session join and session establishment procedure, at least via a signaling diagram and corresponding text.

[00103] Some of the problems that have not been addressed include the following.

[00104] 1. Access to MBS multicast services may be restricted to UEs or groups of UEs. UEs obtain permission to use such MBS services via interaction with the AF creating the MBS service in a PLMN, and the AF provisions information about the authorized users to the PLMN. It is stored per UE in the UDM of the PLMN. However, for roaming users, the UDM is located in the HPLMN and it may be desirable not to store information about services provided locally in the VPLMN in the HPLMN. Otherwise, a technique how to store the information in the UDM of the HPLMN would be required.

[00105] 2. In Rei-18 MBS, assistance information was introduced. The MBS assistance information for an MBS session is an indication that some UEs are preferred to be kept in RRCConnected when the related MBS session that the UE joined is active. The MBS assistance information is also provisioned by the AF that creates the MBS session and stored per UE in the UDM.

[00106] In general, examples herein can focus on additional authorization for roaming users to use specific MBS services which are only open to UEs selected by an AF. In addition, examples may also address the provisioning of MBS assistance information for an MBS session by the AF for roaming users. As background, the MBS assistance information for an MBS session is an optional parameter introduced in Rel-18 multicast and associated with one MBS session, which includes an indication that the UE is preferred to be kept in RRC Connected when the related MBS session that the UE joined is active - note that Rel-18 multicast introduced also a UE in RRC INACTIVE to be able to receive a multicast service.

[00107] Examples with respect to the problems above are addressed as described below.

[00108] As for problem (1), embodiments herein address how to enable inbound roaming UEs to access an MBS service provided locally in the VPLMN which is open only to specific UEs (e.g., an MBS service created by an AF interacting with the VPLMN that also provisions information about the authorized users to the VPLMN). An inbound roaming UE is a roaming UE coming into the VPLMN.

[00109] With respect to problem (2), examples also address how to provision and store MBS assistance information for roaming users receiving an MBS service provided in the VPLMN.

[00110] An overview of certain examples is provided now, and then more details are provided below. As an overview, four alternative techniques to address or overcome at least the problems explained above are as follows.

[00111] Technique 1: MB-SMF stores information about roaming UEs entitled to use MBS sessions and / or MBS assistance information for roaming users. In one embodiment, the AF identifies roaming users and provides information about roaming UEs entitled to use corresponding MBS sessions and / or MBS assistance information for roaming users to the MB-SMF, e.g., as part of the MBS session creation or modification procedure. In another embodiment, the AF uses an existing parameter provisioning procedure towards the UDM in the VPLMN and the UDM identifies roaming users and provides information about roaming UEs entitled to use MBS session and / or MBS assistance information for roaming users to the MB-SMF handling the MBS session.

[00112] Technique 2: A database in VPLMN, e g., UDR, is used to store information about roaming UEs entitled to use MBS session and / or MBS assistance information for roaming users.

[00113] Technique 3: UDM in HPLMN stores information about roaming UEs entitled to use MBS session and / or MBS assistance information for roaming users. In one embodiment, the AF identifies roaming users and provides information about roaming UEs entitled to use MBS sessions and / or MBS assistance information for roaming users to the UDM in the HPLMN. In another embodiment, the AF uses an existing parameter provisioning procedure towards the UDM in the VPLMN and the UDM identifies roaming users and provides information about roaming UEs entitled to use MBS sessions and / or MBS assistance information for roaming users to the UDM in the HPLMN.

[00114] Technique 4: The SMF stores information about roaming UEs entitled to use MBS session and / or MBS assistance information for roaming users.

[00115] Referring to FIG. 1, this figure is a block diagram of a system including a VPLMN and an HPLMN interfacing together, and is an example of a system that can be used to implement the exemplary embodiments herein. In this and other figures, “V” is used to indicate the VPLMN and “H” used to indicate the HPLMN. The (roaming) US 10 can contact the NG-RAN, e.g., as a base station that provides access to the core network in the VPLMN 110. Shown also is a connection between the UE 10 and the AMF 99-IV, although this connection goes through the NG- RAN 70. The reference number 99 is used to indicate a function in a core network. The core network 90V for the VPLMN 110 comprises 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 for the HPLMN 120 comprises the following: NEF 99-4V and UDM 99-5H. The AF 80 is typically outside the core network 90V and 90H.

[00116] Turning to FIG. 1 A, this figure shows a block diagram of one possible and non-limiting example of a cellular network 1 that is connected to a user equipment (UE) 10. A number of network elements are shown in the cellular network of FIG. 1A: a base station 70; and a core network 90. The core network 90 could be core network 90V for the VPLMN or the core network 90H for the HPLMN.

[00117] In FIG. 1 A, a user equipment (UE) 10 is in wireless communication via radio link 11 with the base station 70 of the cellular network 1. A UE 10 is a wireless communication device, such as a mobile device, that is configured to access a cellular network. The UE 10 is illustrated with one or more antennas 28. The ellipses 2 indicate there could be multiple UEs 10 in wireless communication via radio links with the base station 70. 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(s)) 17 and one or more transmitters (Tx(s)) 18. A program 12 is used to cause the UE 10 to perform the operations described herein. For a UE 10, the other circuitry 16 could include circuitry such as for user interface elements (not shown) like a display.

[00118] The base station 70, as a network element of the cellular network 1, provides the UE 10 access to cellular network 1 and to the data network 91 via the core network 90 (e.g., via a user plane function (UPF) of the core network 90). As such, the base station 70 may be considered to be an access node, which provides access by UE(s) 10 to the cellular network 1. The base station 70 is illustrated as having one or more antennas 58. In general, the base station 70 may be referred to as RAN node 70, although many will make reference to this as a gNB (gNode B, a base station for NR, new radio) instead. There are, however, many other examples of RAN nodes including an eNB (evolved Node B) or TRP (Transmission-Reception Point). The base station 70 includes one or more processors 73, one or more memories 75, and other circuitry 76. The other circuitry 76 includes one or more receivers (Rx(s)) 77 and one or more transmitters (Tx(s)) 78. A program 72 is used to cause the base station 70 to perform the operations described herein.

[00119] It is noted that the base station 70 may instead be implemented via other wireless technologies, such as Wi-Fi (a wireless networking protocol that devices use to communicate without direct cable connections). In the case of Wi-Fi, the link 11 could be characterized as a wireless link.

[00120] Two or more base stations 70 communicate using, e.g., link(s) 79. The link(s) 79 may be wired or wireless or both and may implement, e.g., an Xn interface for 5G (fifth generation), an X2 interface for LTE (Long Term Evolution), or other suitable interface for other standards.

[00121] The cellular network 1 may include a core network 90 (e.g., 90H or 90V), as a second network element or elements, that may include core network functionality, and which provide connectivity via a link or links 81 with a data network 91, such as a telephone network and / or a data communications network (e.g., the Internet). The core network 90 includes one or more processors 93, one or more memories 95, and other circuitry 96. The other circuitry 96 includes one or more receivers (Rx(s)) 97 and one or more transmitters (Tx(s)) 98. A program 92 is used to cause the core network 90 to perform the operations described herein.

[00122] The core network 90 could be a 5GC (5G core network). The core network 90 can implement or comprise multiple network functions (NF(s)) 99, and the program 92 may comprise one or more of the NFs 99. A 5G core network may use hardware such as memory and processors and a virtualization layer. It could be a single standalone computing system, a distributed computing system, or a cloud computing system. The NFs 99, as network elements, of the core network could be containers or virtual machines running on the hardware of the computing system(s) making up the core network 90.

[00123] Core network functionality for 5G may include access and mobility management functionality that is provided by a network function 99 such as an access and mobility management function (AMF(s) 99-1), session management functionality that is provided by a network function such as a session management function (SMF 99-2), session management functionality that supports MBS (MB-SMF 99-3), network exposure functionality between the network infrastructure and external entities (NEF 99-4), network management functionality for user data in a single, centralized Unified Data Management element (UDM 99-5), and / or storage functionality to store the user data in a Unified Data Repository (UDR 99-6). Core network functionality for access and mobility management in an LTE (Long Term Evolution) network may be provided by an MME (Mobility Management Entity) and / or SGW (Serving Gateway) functionality, which routes data to the data network. Many others are possible, as illustrated by the examples in FIG. 1A: AMF; SMF; MME; SGW; GMLC (Gateway Mobile Location Center); LMF (Location Management Function); UDM (Unified Data Management) U DR (Unified Data Repository); NRF (Network Repository Function); and / or E-SMLC (Evolved Serving Mobile Location Center). These are merely exemplary core network functionality that may be provided by the core network 90, and note that both 5G and LTE core network functionality might be provided by the core network 90. The base station 70 is coupled via a backhaul link 31 to the core network 90. The base station 70 and the core network 90 may include an NG (Next Generation) interface for 5G, or an SI interface for LTE, or other suitable interface for other radio access technologies for communicating via the backhaul link 31.

[00124] It is noted that clause 6 of 3GPP TS 23.501 VI8.3.0 (2023-09) “provides the functional description of the Network Functions and network entities and the principles for Network Function and Network Function Service discovery and selection.” Descriptions of the following are presented there: AMF(s) 99-1); SMF 99-2; NEF 99-4; UDM 99-5; and UDR 99-6. The MB-SMF 99-3 has similar description in 3GPP TS 23.247 V18.3.0 (2023-09), e.g., §5.3.2.2.

[00125] In the data network 91, there is a computer-readable medium 94. The computer-readable medium 94 contains instructions that, when downloaded and installed into the memories 15, 75, or 95 of the corresponding UE 10, base station 70, and / or core network element(s) 90, and executed by processor(s) 13, 73, or 93, cause the respective device to perform corresponding actions described herein. The computer-readable medium 94 may be implemented in other forms, such as via a compact disc or memory stick.

[00126] The programs 12, 72, and 92 contain instructions stored by 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 apparatus 10, 70, or 90, to perform the operations described herein. The computer readable memories 15, 75, or 95 are circuitry and may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semi con ductor-based memory devices, flash memory, firmware, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories 15, 75, and 95 may be means for performing storage functions. The processors 13, 73, and 93, are circuitry and may be of any type suitable to the local technical environment. For example, these processors may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), processors based on a multi-core processor architecture, and may also include specialized circuits such as field-programmable gate arrays (FPGAs), application specific circuits (ASICs), signal processing devices and other devices, or combinations of these devices, as non-limiting examples. The processors 13, 73, and 93 may be means for causing their respective apparatus to perform functions, such as those described herein.

[00127] The receivers 17, 77, and 97, and the transmitters 18, 78, and 98 may implement wired or wireless interfaces. The receivers and transmitters may be grouped together as transceivers.

[00128] The cellular network 1 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities (such as network functions 99) that result from the network virtualization are still implemented, at some level, using hardware such as processors 73 and / or 93 and memories 75 and / or 95, and also such virtualized entities create technical effects.

[00129] Now that an overview has been provided, more details are provided. The details are separated, at least in part, according to the techniques presented above.

[00130] One assumption used herein is that the UE may obtain permission to use MBS service via interaction with AF. Furthermore, the AF providing MBS data has a business relationship with VPLMN only, i.e., not with HPLMN.

[00131] Furthermore, concerning “authorized UEs” (or authorized users), MBS assistance information may be indicating that certain UEs in the MBS session (not all UEs authorized to access the MBS session) should be kept in an RRC connected state to enable them to talk immediately in a group call. This can also apply without explicit authorization of UEs. 3GPP TS 23.247 defines the MBS assistance information as follows:

[00132] “6.17 Support of Multicast MBS session data reception in UE with RRCIN ACTIVE state

[00133] To provide multicast MBS service to more UEs m a cell, the NG-RAN may decide to move some UE(s) receiving multicast MBS data from RRC CONNECTED to RRC INACTIVE state if the UE(s) is capable to receiving MBS data in RRCINACTIVE state.

[00134] The decision in NG-RAN may use the following information provided from 5GC:

[00135] MBS assistance information for the MBS session, the MBS assistance information for the MBS session is an optional parameter and associated with one MBS session, which consists of an indication that the UE is preferred to be kept in connected when the related MBS session that the UE joined is active. When the NG-RAN node receives this information, the NG-RAN may determine to keep the UE in RRC CONNECTED state even if the MBS session data is supported to be received in RRC INACTIVE state.

[00136] ...

[00137] Per the MBS session that the UE joined, the related "MBS assistance information for the MBS session" is provided to NG-RAN by the SMF if the MBS assistance information is available in the SMF and the MBS session that the UE joined is included in the MBS assistance information. The SMF gets from the UDM the "MBS assistance information", which is provisioned by the AF via the NEF to the UDM as part of the MBS subscription data and includes all the MBS session ID(s), where the UE is preferred to be kept connected when the related MBS session that the UE joined is active (as specified in clause 6.4). The SMF provides the "MBS assistance information for the MBS session" to the NG-RAN as part of the associated PDU session information within the N2 SM information in the procedures where the associated PDU session information need be sent to NG-RAN node, e.g. PDU Session modification for UE joining, handover procedure.”

[00138] One aspect of the embodiments herein is how to make the provisioning of the assistance information work for inbound roaming UEs and MBS sessions in the visited PLMN. Note that the MBS assistance information typically only applies to some of the UEs that joined the multicast session, not all.

[00139] The authorization is described in 3GPP TS 23.247 as follows:

[00140] “6.1.2 UE authorization to the service for multicast

[00141] The following authorizations are defined:

[00142] a) Whether the UE is authorized to use the Multicast service in the PLMN.

[00143] b) The authorization for a UE of receiving the content of a specific multicast MBS session.

[00144] A Multicast MBS session may be ‘open to any UEs’.

[00145] NOTE 1: UE authorization for a specific Multicast MBS session can be implicitly performed when UE is configured for a specific Multicast MBS session, e.g. via Service Announcement for public safety use case.

[00146] NOTE 2: The authorization mentioned by a) is required even if an authorization according to b) is available. If the UE is not authorized to use the Multicast service by the PLMN, the UE is not authorized to join any multicast MBS Session even if the Multicast MBS session is "open to any UEs".

[00147] For a Multicast MBS session, it is required that the 5GC authorizes the UE based on the MBS subscription data and whether the Multicast MBS session is "open to any UEs", which are preconfigured, or provided by the AF (see clause 7.2.9).

[00148] The procedure for UE authorization is a part of UE join procedure and is described in clause 7.2.1.3.”

[00149] The authorization part of examples herein is concerned with 6.1.2(b) above, the term “authorized UE” may be considered to relate to that. However, as a multicast MBS session may be ‘open to any UEs’, this indicates an MBS session may also be open to any UE (and still MBS assistance information can be provided to indicate some UEs within the MBS session). So, the authorization information and the MBS assistance information serves quite different and independent purposes, although both are UE lists related to an MBS session. Both are used herein because the ways to provision this information are almost the same, and similar enhancements can be applied for inbound roaming UEs and an MBS session in a visited PLMN.

[00150] FIG. 2 is an example of a signaling diagram illustrating a first technique (Technique 1) and a first embodiment (Embodiment 1) for that technique. In Technique 1, the MB-SMF 99-3V stores information about roaming UEs 10 entitled to use MBS sessions and / or MBS assistance information for roaming users. FIG. 2 also describes Embodiment 1. In Embodiment 1, the AF 80 connected to VPLMN 110 identifies roaming users, e.g., via MCC / MNC part of GPSI and indicates roaming users entitled to use MBS multicast session and / or MBS assistance information for roaming users to the MB-SMF 99-3V when creating an MBS multicast session via NEF.

[00151] In more detail, in FIG. 2, the roaming UE 10 connects (at least) 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. An NEF 99-4 and AF 80 are also shown. In signaling 202, there is a service announcement for a UE to request access to an MBS multicast service. In response, in block 204, the AF 80 identifies roaming UEs 10. Signaling 206, from the AF 80 to the NEF 99-4, includes an Nnef SMBSession CreateRequest (or Nnef SMBSession ModifyRequest) message with the parameters MBS session ID and GPSI(s) of roaming UE(s) authorized to access the MBS service, and MBS assistance information (e.g., GPSI(s) of roaming UE(s)). In signaling 208, the NEF 99-4 forwards this message to the MB-SMF 99-3 V.

[00152] Signaling 210, 212, and block 214 are optional. In signaling 210, the MB-SMF sends a Nudm ldentity Map request (GPSI) message to the UDM 99-5H that is in the HPLMN 120. The UDM 99-5H responds with Nudm ldentity Map response (SUPI) in signaling 212. In block 214, the MB-SMF 99-3V stores SUPIs of roaming UE(s) authorized to access the MBS service, and MBS assistance information (e.g., SUPIs of roaming UEs).

[00153] Signaling 216 involves the roaming UE 10 sending to the AMF 99-1V an UL NAS message (NI SM container (PDU Session Modification Request (Join MBS session request))). In signaling 218, the AMF 99-1V sends an NsmfPDUSessionUpdateSMContext request message to the SMF 99-2V.

[00154] Signaling 220, 222, and block 224 are optional. In signaling 220, the SMF 99-2V sends an Nmbsmf MBSSession ContextStatusSubscribe request message to the MB-SMF 99-3V. The MB-SMF 99-3V responds with NmbsmfJMBSSession^ContextStatusSubscribe response (SUPIs of roaming UE(s) authorized to access MBS service, MBS assistance information(SUPIs of roaming UEs )). In block 224, the SMG 99-2V performs an authorization check. It is noted that the terms authorization and authentication are considered to be the same herein. In signaling 226, the SMF 99-2V sends to the AMF 99-IV an Nsmf PDUSession UpdateSMContext response (MBS assistance information). In block 228, steps 6 ff in Figure 7.2.1.3-1 of 3GPP TS 23.247 are performed. The“ff” in this context means from and following step 6, e.g., from step 6 to and through later steps.

[00155] For Embodiment 2, the following are example steps. These are illustrated in FIG. 3, which is an example of a signal diagram illustrating a first technique (Technique 1) and a second embodiment (Embodiment 2) for that technique. Many of the signaling and blocks in FIG. 2 are similar to those in FIG. 3, and mainly the differences are described.

[00156] 1 A. AF provides GPSIs of UEs entitled to use MBS session and / or MBS assistance information for roaming users via parameter provisioning procedure via NEF to UDM in VPEMN. See signaling 302, where the AF 80 sends Nnef MBSSession Create Request () to the NEF 99-4, which sends in signaling 304 a Nmbsmf MBSSession Create Request () to the MB-SMF 99-3V. Signaling 202 is performed. Signaling 306 is performed from the AF 80 to the NEF 99-4, using a message of NnefJ’arameterProvision^Create request (MBS session ID, GPSIs of UE(s) authorized to access MBS service, MBS assistance information (GPSIs)). In signaling 308, the NEF forwards this to the UDM 99-5V, which is in the VPEMN 110.

[00157] IB. UDM 99-5V in VPLMN identifies roaming users via MCC / MNC part of GPSI or via lacking UDM entry. If there is no UDM entry for the UE, the UE is assumed to be roaming. See block 310.

[00158] 1C UDM 99-5V in VPLMN discovers MB-SMF handling MBS multicast session via NRF and indicates roaming users entitled to use MBS multicast session and / or MBS assistance information for roaming users to MB-SMF. See, e.g., signaling 312 of NmbsmfParameterProvisionCreate request (MBS session ID, GPSI(s) of roaming UE(s) authorized to access MBS service, MBS assistance information (GPSI() of roaming UEs). More details can be found for IC in 3GPP TS 23.247 and 3GPP TS 23.501.

[00159] 2. MB-SMF 99-3 V passes information about roaming users entitled to join MBS session and / or MBS assistance information for roaming users to SMF when SMF requests information about MBS session. See signaling 220 and 222.

[00160] 3. SMF uses this information for authentication of roaming user trying to join MBS session and / or to provide assistance information to NG-RAN. See block 224.

[00161] In both embodiments, the external identifier of roaming UEs provided by the AF, in an example the GPSI, should be mapped to the internal identifier (e.g., SUPI). Using a new service operation of the UDM, the NEF, UDM in VPLMN, MB-SMF (as shown in the flows), or SMF should contact the UDM in the HPLMN for each roaming UE and request the SUPI that matches the GPSI.

[00162] In Technique 2, there is a database in VPLMN 110, e.g., a UDR 99-6V, stores information about roaming UEs entitled to use MBS session and / or MBS assistance information for roaming users. See FIG. 4, which is an example of a signaling diagram illustrating a second technique (Technique 2). Signaling and operations performed to, from, or by the UDR 99-6V are indicated with the same numbering as in other figures, but with a “-1” added to them.

[00163] 1. AF 80 connected to VPLMN 110 provides GPSIs of UEs entitled to use MBS session and / or MBS assistance information for roaming users via parameter provisioning procedure via NEF to UDM in VPLMN. See signaling 302, 304, 202, 306, and 308.

[00164] 2. UDM 99-5V in VPLMN identifies roaming users via MCC / MNC part of GPSI or via lacking UDM entry. See block 310.

[00165] 3. UDM 99-5V in VPLMN 110 discovers database handling MBS multicast session via NRF (if several databases handle MBS multicast session, each may be assigned to a range of multicast session IDs that the UDM registers at the NRF, and the UDM then uses the MBS session ID for the selection) and indicates roaming users entitled to use MBS multicast session and / or MBS assistance information for roaming users to database in signaling 312-1.

[00166] 4. SMF 99-2V discovers database handling MBS multicast session via NRF (if several databases handle MBS multicast session, each may be assigned to a range of multicast session IDs that a database registers at the NRF, and the UDM then uses the MBS session ID for the selection) and retrieves information about MBS session from database, e.g., when the MBS session information from the MB-SMF indicates that the MBS session is not open to any UE. It is preferable that the SMF subscribes to information about the MBS session and then also obtains notification 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.

[00167] 5. SMF 99-2V uses this information for authentication of a roaming user (UE 10) trying to join an MBS session and / or to provide assistance information to NG-RAN. See block 224.

[00168] Signaling 210-1, 212-1 are performed between the UDR 80 and the UDM 99-5H (e g., instead of between the MB-SMF 99-3V and the UDM 99-5H in FIG. 2), and the UDR 99-6V performs block 214-1 (instead of the MB-SMF 99-3 V as in FIG. 2).

[00169] The external identifier of roaming UEs provided by the AF (e.g., the GPSI) should be mapped to the internal identifier (e.g., SUPI). Using a new service operation of the UDM, it is recommended that NEF, UDM in VPLMN, database or SMF should contact the UDM in the HPLMN for each roaming UE and request the SUPI that matches the GPSI

[00170] Turning to FIG. 4A, this figure is a flow diagram helping explain some of the operations and signaling in FIGS. 3 and 4. For blocks 310 in FIGS. 3 and 4, block 410 of FIG. 4A helps explain the operations there. In block 410, the UDM in VPLMN receives a request to store information related to an MBS session that contains identifiers of UEs, where the identifiers of UEs comprise identifiers of roaming UEs and can also comprise identifiers of nonroaming UEs. In block 420, the UDM identifies the roaming UEs and sends a request to store related authorization information and / or assistance information to the MB-SMF (FIG. 3) or UDR (FIG. 4). Block 420 in FIG. 4A relates in part to blocks 310 and in part to signaling in FIGS. 3 and 4 that occurs after block 310 in those figures.

[00171] Concerning Technique 3, this example has the UDM in HPLMN storing information for roaming UEs entitled to use MBS session and / or MBS assistance information for roaming users. There are two embodiments for this example.

[00172] Embodiment 1 is described in conjunction with FIG. 5, which is an example of a signaling diagram illustrating a third technique (Technique 3) and a first embodiment (Embodiment 1) for that technique.

[00173] 1 A. AF 80 connected to VPLMN 110 identifies (see block 310) roaming users via an MCC / MNC part of GPSI and for roaming users uses a NEF in corresponding HPLMN for parameter provisioning procedure to indicate GPSI of roaming users entitled to use MBS multicast session to NEF and / or MBS assistance information for roaming users. AF may include service class and VPLMN where service is provided. This is part of the initial flow, including blocks 302, 304, 202, and 306-1. In block 306-1, this has signaling from the AF 80 to the NEF 99-4H in the HPLMN 120 of Nnef ParameterProvision Create request (MBS session ID, GPSIs of roaming UE(s) authorized to access MBS service, MBS assistance information (GPSIs of roaming UEs, VPLMN ID, service class).

[00174] IB. The NEF 99-4H in HPLMN 120 forwards parameter provisioning to UDM 99-5H in HPLMN 120. See signaling 312-2 of NudmJ’arameterProvision^Create request (MBS session ID, GPSIs of roaming UE(s) authorized to access MBS service, MBS assistance information(GPSIs of roaming UEs, VPLMN ID, service class).

[00175] IC. UDM 99-5H in HPLMN 120 stores, e.g., as part of the user subscription data, that the user is authorized to use indicated MBS session and / or MBS assistance information for roaming users. UDM 99-5H in HPLMN 120 may also check if user is authorized to use MBS service by considering configured information about the user being allowed to access MBS services when roaming, and possibly about service classes and VPLMNs where this information applies and otherwise rejects storage request. See block 502, where the UDM 99-5H maps GPSIs to SUPIs, and block 504, where the UDM 99-5H checks if UEs are authorized for MBS services in VPLMN. See also block 506, where the UDM 99-5H stores SUPIs of roaming UE(s) authorized to access MBS service, and MBS assistance information (SUPIs of roaming UEs).

[00176] In block 508, there is a PDU session establishment, see 3GPP TS 23.247 Clause 7.2.1.2. Signaling 510 and 512 are optional. In signaling 510, there is a message of Nudm SDM Get request (SUPI) from the SMG 99-2V to the UDM 99-5H., and the UDM 99-5H responds with Nudm SDM Get response (MBS subscription information, MBS assistance information).

[00177] With respect to Embodiment 2, this is described in part by FIG. 6, which is an example of a signaling diagram illustrating a third technique (Technique 3) and a second embodiment (Embodiment 2) for that technique.

[00178] 1 A. AF 80 provides GPSIs of UEs entitled to use MBS session and / or MBS assistance information for roaming users via parameter provisioning procedure via NEF 99-4V in VPLMN 110 to UDM 99-5V in VPLMN 110. See signaling 306 and 602, which occur after signaling 302, 304, and 202 in this example.

[00179] 1B UDM 9-6V in VPLMN 110 identifies roaming users via MCC / MNC part of GPSI or via lacking UDM entry. See block 310, which is performed after signaling 360 and reception of the corresponding GPSIs.

[00180] IC. For roaming users, UDM 99-5V in VPLMN 110 discovers UDM 99-5H in HPLMN 120 handling those users via NRF and for each such user indicates that the user is entitled to use MBS multicast session and / or MBS assistance information for those users to UDM 99-5H in HPLMN 120 handling that user. See the signaling 604, where the UDM 99-5V sends the following message to the UDM 99-5H: NudmParameterProvision Create request (MBS session ID, GPSI(s) of roaming UE(s) authorized to access MBS service, MBS assistance information(GPSI(s) of roaming UEs, VPLMN ID).

[00181] 1D. UDM in HPLMN stores as part of the user subscription data that the user is authorized to use indicated MBS session and / or MBS assistance information for that users. UDM in HPLMN may also check if a user is authorized to use MBS service by comparing configured information about the user being allowed to access MBS services when roaming, and possibly about service classes and VPLMNs where this information applies and otherwise rejects storage request. See block 502, where the UDM 99-5H maps GPSIs to SUPIs, and block 504, where the UDM 99-5H checks if UEs are authorized for MBS services in VPLMN. In block 506, the UDM 99-5H stores SUPIs of roaming UE(s) authorized to access MBS service, MBS assistance information (e.g., SUPIs of roaming UEs).

[00182] 2. When a roaming UE 10 registers, SMF 99-2V m VPLMN 110 may retrieve / subscribe to user subscription information (that includes information about MBS session) from UDM in HPLMN. See signaling 508, 510, and 512.

[00183] 3. SMF 99-2V uses this information for authentication of user trying to join MBS session and / or to provide assistance information to NG-RAN 70. For instance, in signaling 60t, the roaming UE 10 sends a message, to the AMF 99-IV, to store SUPIs of roaming UE(s) authorized to access MBS service, MBS assistance information (SUPIs of roaming UEs). The AMF 99-1V responds by sending signaling 608, an NsmfPDUSessionUpdateSMContext request, to the SMF 99-2V, which then responds by performing an authentication check in block 224224 associated with the UE 10.

[00184] Referring to FIG. 6A, this figure is a flow diagram helping explain a check for a roaming UE in FIGS. 5 and 6. Such a check can be performed by block 504 of FIGS. 5 and 6 and one example is illustrated by block 627, where checking is performed by the UDM for each received Generic Public Subscription Identifiers of a roaming UE, whether that roaming UE is authorized to access the MBS service using at least one of the received VPLMN ID, the received service class, stored information whether the UE is entitled to receive MBS services when roaming, stored information about VPLMNs from which the UE is entitled to receive MBS services when roaming, or stored information about service classes of MBS services that the UE is entitled to receive when roaming.

[00185] Technique 4 is presented now. FIG. 7 is an example of a signaling diagram illustrating a fourth technique (Technique 4). In an example of this technique, the SMF 99-2V stores roaming UEs entitled to use MBS session and / or MBS assistance information for roaming users.

[00186] 1. AF 80 connected to VPLMN 11 provides GPSIs of UEs entitled to use MBS session and / or MBS assistance information for roaming users via parameter provisioning procedure via NEF to UDM in VPLMN. See signaling 306, which in this example occurs after signaling 302, 304, and 202.

[00187] 2. UDM 99-5V in VPLMN identifies roaming users 10 via MCC / MNC part of GPSI or via lacking UDM entry. See block 310.

[00188] 3. UDM 99-5V in VPLMN 110 discovers SMF(s) 99-2V handling roaming users via the UDM 99-5H in HPLMN 120 and indicates to each SMF the roaming users served by the SMF 99-2V that are entitled to use MBS multicast session and / or MBS assistance information for the roaming users. If a UE is served by multiple SMFs 99-2V of the VPLMN, the UDM in the VPLMN provides the information related to that UE to all those SMFs. The SMF stores this information related to a roaming UE as long as the SMF serves the roaming UE. See signaling 702, where the UDM 99-5V sends a Nudm^UECM^Get request (NFtype=SMF, GPSI) message to the UDM 99-5H, which returns in signaling 704 a Nudm UECM Get response (SMF ID(s) SUPI). In signaling 705, the UDM 99-5V sends to the SMF 99-2V a message of Nsmf ParameterProvision Create request (MBS session ID, SUPI(s) of roaming UE(s) authorized to access MBS service, MBS assistance information (SUPISI() of roaming UEs). For storage, the SMF 99-2V stores SUPIs of roaming UE(s) authorized to access MBS service, MBS assistance information (e.g., SUPIs of roaming UEs), see block 708.

[00189] 4. SMF 99-2V uses this information for authentication of roaming user trying to join MBS session and / or to provide assistance information to NG-RAN. See the authorization check in block 224, which is responsive to the signaling in 606 and 608, and has a response via signaling 226.

[00190] Referring to FIG. 8, this is a flow diagram illustrating parts of Technique 1 at the MB-SMF. For instance, see blocks 206 and 208 of FIG. 2. In block 810, this includes storing, at an MB-SMF in a VPLMN for roaming UEs, in relation to an MBS session, at least one of information about roaming UEs authorized to use the MBS session or corresponding information about MBS assistance for the MBS session related to the roaming UEs. Block 815 includes receiving, by the MB-SMF from an SMF in the VPLMN, a request for a context status subscribe for the MBS session. Block 820 comprises sending, by the MB-SMF using the stored information and in response to the request, 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 comprising identifiers of related roaming UEs.

[00191] An example of the flow of FIG. 8 may further include where the one or more identifiers comprise subscription permanent identifiers, and the method further comprises: receiving, by the MB-SMF, an identification of an MBS session, and at least one of generic public subscription identifiers of the roaming UEs authorized to access the MBS session or information about MBS assistance for the MBS session comprising the generic public subscription identifiers of the related roaming UEs; sending, by the MB-SMF to a UDM in an HPLMN, a request to convert the generic public subscription identifiers of selected one or more roaming UEs to subscription permanent identifiers; and receiving, by the MB-SMF from the UDM in the HPLMN, subscription permanent identifiers corresponding to the selected one or more roaming UEs to be used in the sending the one or more identifiers of the selected roaming UEs. Also, the storing comprises storing the subscription permanent identifiers corresponding to the selected one or more roaming UEs. Consider blocks 208, 210, and 212 of FIG. 2.

[00192] The example of the previous paragraph has a further example wherein the identification of the MBS session, and at least one of the generic public subscription identifiers of the roaming UEs authorized to access the MBS session as an MBS service or corresponding information about MBS assistance for the MBS session comprising the generic public subscription identifiers of the related roaming UEs that are received by the MB-SMF: from an NEF using one of a message to create an MBS session or a message to modify an MBS session; or from a UDM in the VPLMN using a message to provide parameters related to the MBS session. See, e.g., FIG. 2 at block 208 and FIG. 3 at block 312.

[00193] FIG. 9 is a flow diagram illustrating corresponding parts of Technique 1 at the SMF. Block 910 includes receiving, by an SMF in a VPLMN for roaming UEs from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session. Block 920 comprises sending, by the SMF to an MB-SMF in the VPLMN, a request for information about the MBS session. Block 930 includes 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 comprising identifiers of related roaming UEs. Block 940 has performing, by the SMF, an authorization check to determine whether the roaming UE is authorized to access the MBS session. Block 950 includes sending, by the SMF to the AMF, a response to the indication that the roaming UE wants to join the MBS session indicating the UE is authorized to join the MBS session. See, e.g., blocks 218, 220, 222, 224, and more of FIG. 2

[00194] Another example of the flow of FIG. 9 is wherein the one or more identifiers comprise subscription permanent identifiers. A further example m this and the previous paragraph includes wherein the authorization check to determine whether the roaming UE that wants to join the MBS session is authorized to access the MBS session considers whether the one of one or more received identifiers of roaming UEs authorized to access the MBS session comprises an identifier of the roaming UE received in the indication.

[00195] A further example for the previous two paragraphs includes wherein the response to the indication that the roaming UE wants to join the MBS session comprises MBS assistance information for the MBS session based on the received identifiers of roaming UEs related to the information of MBS assistance comprising the identifiers of the roaming UEs that want to join the MBS session.

[00196] FIG. 10 is a flow diagram illustrating corresponding parts of Technique 1 at the NEF. FIG. 10 is related at least in part to the operations performed by NEF in FIG. 2. Block 1010 includes receiving, at an NEF from an AF, a message to create or modify an MBS session, comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access an MBS session, or information for MBS assistance for the MBS session related to roaming UEs. Block 1015 includes forwarding, from the NEF to an MB-SMF in a VPLMN of the roaming UEs, the message.

[00197] FIG. 11 is a flow diagram of operations of the UDM as applied to FIGS. 3 and 4. The flow includes block 1110 that includes receiving, at a UDM in a VPLMN of roaming UEs, a request to store information related to an MBS session comprising an identifier of the MBS session and at least one of 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 comprising identifiers of related UEs. In block 1115, this includes determining, by the UDM, inbound roaming UEs out of at least one of the one or more UEs authorized to access the MBS session and the UEs related to the information about MBS assistance. Block 1120 includes sending, by the UDM, a request to store information related to the MBS session to an MB-SMF or UDR, the request comprising the identifier of the MBS session and at least one of the identifiers corresponding to the determined inbound roaming UEs authorized to access the MBS session, and information about MBS assistance for the MBS session comprising identifiers of the determined inbound roaming UEs.

[00198] Referring to FIG. 12, this figure is a flow diagram of operations of the UDR as applied at least to FIG. 4. Block 1210 includes storing, at a UDR in a VPLMN of roaming UEs, an identifier of an MBS session and at least one of 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 comprising identifiers of related roaming UEs. Block 1220 includes receiving, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session and comprising a session ID for the MBS session. Block 1230 comprises sending, by the UDR to the SMF using the stored information and in response to the request, at least one of 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 comprising the identifiers of the related roaming UEs.

[00199] As another example, the flow diagram of FIG. 12 includes the one or more identifiers comprise subscription permanent identifiers. Also, the method further comprises: receiving, by the UDR, an identification of the MBS session, and at least one of a generic public subscription identifiers of the roaming UEs authorized to access the MBS session and information about MBS assistance for the MBS session comprising the generic public subscription identifiers of the related roaming UE; sending, by the UDR to a UDM in an HPLMN, a request to convert the generic public subscription identifiers of selected one or more UEs to subscription permanent identifiers; and receiving, by the UDR from the UDM in the HPLMN, subscription permanent identifiers corresponding to the selected one or more UEs to be used in the sending the one or more identifiers of UEs. The storing comprises storing the subscription permanent identifiers corresponding to the selected one or more UEs.

[00200] FIG. 13 is a flow diagram of operations of the SMF as applied at least to FIG. 4. Block 910 includes receiving, by an SMF in a VPLMN of roaming UEs and from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session, and block 920 includes sending, by the SMF to a UDR in the VPLMN, a request for a subscription for information related to the MBS session and comprising a session ID for the MBS session. Block 930 includes receiving, by the SMF and from a UDR in the VPLMN and in response to the request, information comprising 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 comprising identifiers of related roaming UEs. Block 940 comprises performing, by the SMF, an authorization check for the roaming UE to see if the roaming UE is authorized to access the MBS session. Block 950 includes sending, by the SMF to the AMF, a response to the indication that a roaming UE wants to join an MBS session, information for MBS assistance indicating the UE is authorized to join the MBS session.

[00201] Another example of the flow is wherein the authorization check to determine whether the roaming UE that wants to join the MBS session is authorized to access the MBS session considers whether the one of one or more identifiers of roaming UEs authorized to access the MBS session comprises the identifier of the roaming UE. A further example of the flow and the previous example includes wherein the response to the indication that the roaming UE wants to join the MBS session comprises MBS assistance information for the MBS session based on received identifiers of roaming UEs related to the information of MBS assistance comprising the received identifiers of the roaming UEs that want to join the MBS session.

[00202]

[00203] FIG. 14 is a flow diagram of operations of the LJ D AI as applied at least to FIGS. 5 and 6. In block 1410, this includes receiving, at a UDM in an HPLMN for roaming UEs from an NEF in the HPLMN or an UDM in an VPLMN, a request for storing information related to an MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs, a VPLMN ID, and a service class. Block 1420 includes checking, by the UDM for individual received Generic Public Subscription Identifiers of a roaming UE, whether that roaming UE is authorized to access an MBS service for the MBS session using at least one of the received VPLMN ID, the received service class, stored information whether the UE is entitled to receive MBS services when roaming, stored information about VPLMNs from which the UE is entitled to receive MBS services when roaming, or stored information about service classes of MBS services that the UE is entitled to receive when roaming. Block 1430 includes storing, by the UDM for individual ones of those roaming UEs that are authorized to receive the MBS service in the VPLMN, at least one of the identification of an authorized MBS session corresponding to the MBS service or information for MBS assistance for the MBS session.

[00204] An example of the flow 1430 can further include wherein the stored information comprises at least one of the identification of the authorized MBS service and information for MBS assistance related to a roaming UEs is identified using Subscription Permanent Identifiers of the roaming UE and wherein the method further comprises: mapping, by the UDM, the Generic Public Subscription Identifiers of roaming UEs authorized to access the MBS session to Subscription Permanent Identifiers so the Subscription Permanent Identifiers are then stored corresponding to the roaming UEs authorized to access the MBS session.

[00205] Another example that can be applied to the previous two paragraphs,may further comprise: receiving, by the UDM from an SMF in the VPLMN, a request with an identifier of a roaming UE; and sending, from the UDM to the SMF, a response, to the request with an identifier of a roaming UE, with stored information comprising at least one of the identifications of the authorized MBS sessions and information for MBS assistance for MBS sessions.

[00206] FIG. 15 is a flow diagram of operations of the AF as applied at least to FIG. 5. Block 1510 includes identifying, at an AF providing data for an MBS session in a PLMN, UEs authorized to participate in the MBS session that have a different PLMN as HPLMN and their HPLMN. Block 1520 includes sending, from the AF towards an NEF in the HPLMN, a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, and a service class.

[00207] FIG. 16 is a flow diagram of operations of the UDM as applied at least to FIG. 5. Block 1610 includes receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs, or a service class. Block 1620 comprises identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN. Block 1630 includes sending, from the UDM in the PLMN towards a UDM in the HPLMN a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, or a service class.

[00208] FIG. 17 is a flow diagram of operations of the UDM as applied at least to FIG. 5. Block 1710 included receiving, at an UDM in a PLMN where an MBS session is provided from an NEE in the PLMN, a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, or information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs. Block 1720 includes identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN. Block 1730 includes sending, for individual identified UEs, from the UDM in the PLMN towards a UDM in the HPLMN of the identified UE, a request to provision identifiers of SMFs handling the identified UE, the request comprising the Generic Public Subscription Identifiers of the identified UE. Block 1740 comprises receiving, for individual identified UEs, at the UDM m the PLMN from the UDM in the HPLMN of the identified UE, a response comprising at least one identifier of an SMF handling the identified UE and a Subscription Permanent Identifier of the identified UE. Block 1750 includes sending, for individual identified UEs, from the UDM in the PLMN towards the SMF, a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of the Subscription Permanent Identifier of the identified roaming UE to indicate that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance comprising Subscription Permanent Identifier of the identified roaming UE.

[00209] FIG. 18 is a flow diagram of operations of the SMF as applied at least to FIG. 7. Block 1810 includes receiving, by an SMF in an VPLMN of roaming UEs from a UDM in the VPLMN, a request to provision data for an MBS session, the request comprising an identification of the MBS session, and at least one of a Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, and information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE. Block 1820 includes storing, by the SMF the received identification of the MBS session, and at least one of the received Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, or the received information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE. Block 1320 comprises receiving, by the SMF from an AMF m the VPLMN, an indication that a 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 to the AMF, a response to the indication that the roaming UE wants to join the MBS session indicating the UE is authorized to join the MBS session.

[00210] The flow of FIG. 18 may also 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 considers whether stored one or more identifiers of roaming UEs authorized to access the MBS session comprises the identifier of the roaming UE.

[00211] The flows of the previous two paragraphs may also include wherein the response to the indication that the roaming UE wants to join the MBS session comprises MBS assistance information for the MBS session if the stored one or more identifiers of roaming UEs related to the information of MBS assistance comprises the identifiers of the roaming UEs that want to join the MBS session.

[00212] The flows of FIGS. 13-18 and other examples for these flows may be implemented by s computer program, comprising instructions for performing the methods of any of the flows, when the computer program is run on an apparatus. The computer program may be a computer program product comprising a computer-readable medium bearing instructions embodied therein for use with the apparatus. The computer program may be directly loadable into an internal memory of the apparatus.

[00213] Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect and / or advantage of one or more of the example embodiments disclosed herein, for at least Technique 1, is there is no impact to HPLMN for MBS service in VPLMN, and there is no new network entity that is used. Another technical effect and / or advantage of one or more of the example embodiments disclosed herein is, e g., for at least Technique 2, that there is no impact to HPLMN for MBS service in VPLMN. Another technical effect and / or advantage of one or more of the example embodiments disclosed herein, for at least Technique 3, is there are minimal impacts to existing procedures.

[00214] The following are additional examples.

[00215] Example 1. An apparatus, comprising means for performing: storing, at an MB-SMF in a VPLMN for roaming UEs, in relation to an MBS session, at least one of information about roaming UEs authorized to use the MBS session or corresponding information about MBS assistance for the MBS session related to the roaming UEs; receiving, by the MB-SMF from an SMF in the VPLMN, a request for a context status subscribe for the MBS session; and sending, by the MB-SMF using the stored information and in response to the request, 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 comprising identifiers of related roaming UEs.

[00216] Example 2. The apparatus according to example 1, wherein: the one or more identifiers comprise subscription permanent identifiers; the means are further configured for performing: receiving, by the MB-SMF, an identification of an MBS session, and at least one of generic public subscription identifiers of the roaming UEs authorized to access the MBS session or information about MBS assistance for the MBS session comprising the generic public subscription identifiers of the roaming UEs authorized to access the MBS session; sending, by the MB-SMF to a UDM in an HPLMN, a request to convert the generic public subscription identifiers of selected one or more roaming UEs to subscription permanent identifiers; and receiving, by the MB-SMF from the UDM in the HPLMN, subscription permanent identifiers corresponding to the selected one or more roaming UEs to be used in the sending the one or more identifiers of the selected roaming UEs; and the storing comprises storing the subscription permanent identifiers corresponding to the selected one or more roaming UEs.

[00217] Example 3. The apparatus according to example 2, wherein the identification of the MBS session, and at least one of the generic public subscription identifiers of the UEs authorized to access the MBS session as an MBS service and corresponding information about MBS assistance for the MBS session comprising identifiers of related roaming users that are received by the MB-SMF: from an NEF using one of a message to create an MBS session or a message to modify an MBS session; or from a UDM in the VPLMN using a message to provide parameters related to the MBS session.

[00218] Example 4. An apparatus, comprising means for performing: receiving, by an SMF in a VPLMN for roaming UEs from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to an MB-SMF in the VPLMN, a request for information about the MBS session; 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 comprising identifiers of related roaming UEs; 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 indicating the UE is authorized to join the MBS session.

[00219] Example 5. The apparatus according to example 4, wherein the one or more identifiers comprise subscription permanent identifiers.

[00220] Example 6. The apparatus according to examples 4 or 5 wherein the authorization check to determine whether the roaming UE that wants to join the MBS session is authorized to access the MBS session considers whether the one of one or more received identifiers of roaming UEs authorized to access the MBS session comprises an identifier of the roaming UE received in the indication.

[00221] Example 7. The apparatus according to any of examples 4 to 6, wherein the response to the indication that the roaming UE wants to join the MBS session comprises MBS assistance information for the MBS session based on the received identifiers of roaming UEs related to the information of MBS assistance comprising the identifiers of the roaming UEs that want to join the MBS session.

[00222] Example 8. An apparatus, comprising means for performing: receiving, at an NEF from an AF, a message to create or modify an MBS session, comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access an MBS session, or information for MBS assistance for the MBS session related to roaming UEs; and forwarding, from the NEF to an MB-SMF in a VPLMN of the roaming UEs, the message.

[00223] Example 9. An apparatus, comprising means for performing: receiving, at a UDM in a VPLMN of roaming UEs, a request to store information related to an MBS session comprising an identifier of the MBS session and at least one of 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 comprising identifiers of related UEs; determining, by the UDM, inbound roaming UEs out of at least one of the one or more UEs authorized to access the MBS session and the UEs 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 UDR, the request comprising the identifier of the MBS session and at least one of the identifiers corresponding to the determined inbound roaming UEs authorized to access the MBS session, and information about MBS assistance for the MBS session comprising identifiers of the determined inbound roaming UEs.

[00224] Example 10. An apparatus, comprising means for performing: storing, at a UDR in a VPLMN of roaming UEs, an identifier of an MBS session and at least one of 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 comprising identifiers of related roaming UEs; receiving, by the UDR from an SMF in the VPLMN, a request for a subscription for the MBS session and comprising a session ID for the MBS session; and sending, by the UDR to the SMF using the stored information and in response to the request, at least one of 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 comprising the identifiers of the related roaming UEs.

[00225] Example 11. The apparatus according to example 10, wherein: the one or more identifiers comprise subscription permanent identifiers; the means are further configured for performing: receiving, by the UDR, an identification of the MBS session, and at least one of a generic public subscription identifiers of the roaming UEs authorized to access the MBS session and information about MBS assistance for the MBS session comprising the generic public subscription identifiers of the related roaming UE; sending, by the UDR to a UDM in an HPLMN, a request to convert the generic public subscription identifiers of selected one or more UEs to subscription permanent identifiers; and receiving, by the UDR from the UDM in the HPLMN, subscription permanent identifiers corresponding to the selected one or more UEs to be used in the sending the one or more identifiers of UEs; and the storing comprises storing the subscription permanent identifiers corresponding to the selected one or more UEs.

[00226] Example 12. An apparatus, comprising means for performing: receiving, by an SMF in a VPLMN of roaming UEs and from an AMF in the VPLMN, an indication that a roaming UE wants to join an MBS session; sending, by the SMF to a UDR in the VPLMN, a request for a subscription for information related to the MBS session and comprising a session ID for the MBS session; receiving, by the SMF and from a UDR in the VPLMN and in response to the request, information comprising 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 comprising identifiers of related 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 to the AMF, a response to the indication that a roaming UE wants to join an MBS session, information for MBS assistance indicating the UE is authorized to join the MBS session.

[00227] Example 13. The apparatus according to example 12, wherein the authorization check to determine whether the roaming UE that wants to join the MBS session is authorized to access the MBS session considers whether the one of one or more identifiers of roaming UEs authorized to access the MBS session comprises the identifier of the roaming UE.

[00228] Example 14. The apparatus according to any of examples 12 to 13, wherein the response to the indication that the roaming UE wants to join the MBS session comprises MBS assistance information for the MBS session based on received identifiers of roaming UEs related to the information of MBS assistance comprising the received identifiers of the roaming UEs that want to join the MBS session.

[00229] Example 15. An apparatus, comprising means for performing: receiving, at a UDM in an HPLMN for roaming UEs from an NEF in the HPLMN or an UDM in an VPLMN, a request for storing information related to an MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs, a VPLMN ID, and a service class; checking, by the UDM for individual received Generic Public Subscription Identifiers of a roaming UE, whether that roaming UE is authorized to access an MBS service for the MBS session using at least one of the received VPLMN ID, the received service class, stored information whether the UE is entitled to receive MBS services when roaming, stored information about VPLMNs from which the UE is entitled to receive MBS services when roaming, or stored information about service classes of MBS services that the UE is entitled to receive when roaming; and storing, by the UDM for individual ones of those roaming UEs that are authorized to receive the MBS service in the VPLMN, at least one of the identification of an authorized MBS session corresponding to the MBS service or information for MBS assistance for the MBS session.

[00230] Example 16. The apparatus according to example 15, wherein the stored information comprises at least one of the identification of the authorized MBS service and information for MBS assistance related to a roaming UEs is identified using Subscription Permanent Identifiers of the roaming UE and wherein the means are further configured for performing: mapping, by the UDM, the Generic Public Subscription Identifiers of roaming UEs authorized to access the MBS session to Subscription Permanent Identifiers so the Subscription Permanent Identifiers are then stored corresponding to the roaming UEs authorized to access the MBS session.

[00231] Example 17. The apparatus according to any one of examples 15 or 16, wherein the means are further configured for performing: receiving, by the UDM from an SMF in the VPLMN, a request with an identifier of a roaming UE; and sending, from the UDM to the SMF, a response, to the request with an identifier of a roaming UE, with stored information comprising at least one of the identifications of the authorized MBS sessions and information for MBS assistance for MBS sessions.

[00232] Example 18. An apparatus, comprising means for performing: identifying, at an AF providing data for an MBS session in a PLMN, UEs authorized to participate in the MBS session that have a different PLMN as HPLMN and their HPLMN; and sending, from the AF towards an NEF in the HPLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, and a service class.

[00233] Example 19. An apparatus, comprising means for performing: receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs, or a service class; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; and sending, from the UDM in the PLMN towards a UDM in the HPLMN a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of roaming UEs from the HPLMN authorized to access the MBS session, information for MBS assistance comprising Generic Public Subscription Identifiers of related roaming UEs from the HPLMN, PLMN ID of the PLMN where the MBS session is provided, or a service class.

[00234] Example 20. An apparatus, comprising means for performing: receiving, at an UDM in a PLMN where an MBS session is provided from an NEF in the PLMN, a request to provision data for the MBS session, the request comprising at least one of an identification of the MBS session, and at least one of Generic Public Subscription Identifiers of UEs authorized to access the MBS session, or information for MBS assistance comprising Generic Public Subscription Identifiers of related UEs; identifying, at the UDM, Generic Public Subscription Identifiers of UEs that have a different PLMN as HPLMN and their HPLMN; sending, for individual identified UEs, from the UDM in the PLMN towards a UDM in the HPLMN of the identified UE, a request to provision identifiers of SMFs handling the identified UE, the request comprising the Generic Public Subscription Identifiers of the identified UE; receiving, for individual identified UEs, at the UDM in the PLMN from the UDM in the HPLMN of the identified UE, a response comprising at least one identifier of an SMF handling the identified UE and a Subscription Permanent Identifier of the identified UE; and sending, for individual identified UEs, from the UDM in the PLMN towards the SMF, a request to provision data for the MBS session, the request comprising an identification of the MBS session, and at least one of the Subscription Permanent Identifier of the identified roaming UE to indicate that the identified roaming UE is authorized to access the MBS session, or information for MBS assistance comprising Subscription Permanent Identifier of the identified roaming UE.

[00235] Example 21. An apparatus, comprising means for performing: receiving, by an SMF in an VPLMN of roaming UEs from a UDM in the VPLMN, a request to provision data for an MBS session, the request comprising an identification of the MBS session, and at least one of a Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, and information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; storing, by the SMF the received identification of the MBS session, and at least one of the received Subscription Permanent Identifier of a roaming UE to indicate that it is authorized to access the MBS session, or the received information for MBS assistance comprising Subscription Permanent Identifier of a roaming UE; receiving, by the SMF from an AMF in the VPLMN, an indication that a 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 indicating the UE is authorized to join the MBS session.

[00236] Example 22. The apparatus according to example 21, wherein the authorization check to determine whether the roaming UE that wants to join the MBS session is authorized to access the MBS session considers whether stored one or more identifiers of roaming UEs authorized to access the MBS session comprises the identifier of the roaming UE.

[00237] Example 23. The apparatus according to any of examples 21 to 22, wherein the response to the indication that the roaming UE wants to join the MBS session comprises MBS assistance information for the MBS session if the stored one or more identifiers of roaming UEs related to the information of MBS assistance comprises the identifiers of the roaming UEs that want to join the MBS session.

[00238] Example 24. The apparatus of any preceding apparatus example, wherein the means comprises: at least one processor; and at least one memory storing instructions that, when executed by at least one processor, cause the performance of the apparatus.

[00239] As used in this application, the term “circuitry” may refer to one or more or all of the following:

[00240] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and

[00241] (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

[00242] (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[00243] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[00244] Embodiments herein may be implemented in software (executed by one or more processors), hardware (e.g., an application specific integrated circuit), or a combination of software and hardware. In an example embodiment, the software (e.g., application logic, an instruction set) is maintained on any one of various conventional computer-readable media. In the context of this document, a “computer-readable medium” may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted, e.g., in FIG. 1 A. A computer-readable medium may comprise a computer-readable storage medium (e.g., memories 15, 75, and 95 or other device) that may be any media or means that can contain, store, and / or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable storage medium does not comprise propagating signals, and therefore may be considered to be non-transitory. The term “non-transitory”, as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM, random access memory, versus ROM, read-only memory).

[00245] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.

[00246] Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[00247] It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

[00248] The following abbreviations that may be found in the specification and / or the drawing figures are defined as follows:

[00249] 5G fifth generation

[00250] AF application function

[00251] AMF access and mobility management function

[00252] E-SMLC evolved serving mobile location center

[00253] GMLC Gateway Mobile Location Center

[00254] GPSI Generic Public Subscription Identifier

[00255] eNB (or eNodeB) evolved Node B (e.g., an LTE base station)

[00256] gNB (or gNodeB) base station for 5G / NR

[00257]

[00258] HPLMN ID home PLMN identification

[00259] I / F interface

[00260] LMF Location Management Function 5

[00261] LTE long term evolution

[00262] MRS Multicast / Broadcast Services

[00263] MB-SMF multicast broadcast session management function

[00264] MCC mobile country code

[00265] MME mobility management entity 10

[00266] MNC mobile network code

[00267] NEF network exposure function

[00268] NF network function

[00269] ng or NG next generation

[00270] NG-RAN next generation RAN 15

[00271] NR new radio

[00272] NRF Network Repository Function

[00273] N / WorNW network

[00274] PLMN public land mobile network

[00275] RAN radio access network 20

[00276] Rei release

[00277] Rx receiver

[00278] SGW serving gateway

[00279] SMF session management function

[00280] SUPI Subscription Permanent Identifier 25

[00281] TRP transmission-reception point

[00282] Tx transmitter

[00283] UDM unified data management

[00284] UDR unified data repository

[00285] UE user equipment (e.g., a wireless, typically mobile 30 device)

[00286] UL

[00287] UPF

[00288] VPLMN uplink (from UE to network) user plane function visiting PLMN

Claims

1. An apparatus, comprising means for performing:storing, at a multicast broadcast session management function in a visiting public land mobile network for roaming user equipment, in relation to a multicast / broadcast services session, at least one of information about roaming user equipment authorized to use the multicast / broadcast services session or corresponding information about multicast / broadcast services assistance for the multicast / broadcast services session related to the roaming user equipment;receiving, by the multicast broadcast session management function from a session management function in the visiting public land mobile network, a request for a context status subscribe for the multicast / broadcast services session; andsending, by the multicast broadcast session management function using the stored information and in response to the request, at least one of one or more identifiers of user equipment authorized to access the multicast / broadcast services session or information about multicast / broadcast services assistance for the multicast / broadcast services session comprising identifiers of related roaming user equipment.

2. The apparatus according to claim 1, wherein:the one or more identifiers comprise subscription permanent identifiers;the means are further configured for performing:receiving, by the multicast broadcast session management function, an identification of a multicast / broadcast services session, and at least one of generic public subscription identifiers of the roaming user equipment authorized to access the multicast / broadcast services session or information about multicast / broadcast services assistance for the multicast / broadcast services session comprising the generic public subscription identifiers of the related roaming user equipment;sending, by the multicast broadcast session management function to a unified data management in a home public land mobile network, a request to convert the generic public subscription identifiers of selected one or more roaming user equipment to subscription permanent identifiers; andreceiving, by the multicast broadcast session management function from the unified data management in the home public land mobile network, subscription permanent identifiers corresponding to the selected one or more roaming user equipment to be used in the sending the one or more identifiers of the selected roaming user equipment; andthe storing comprises storing the subscription permanent identifiers corresponding to the selected one or more roaming user equipment.

3. The apparatus according to claim 2, wherein the identification of the multicast / broadcast services session, and at least one of the generic public subscription identifiers of the roaming user equipment authorized to access the multicast / broadcast sendees session as a multicast / broadcast services service or corresponding information about multicast / broadcast services assistance for the multicast / broadcast services session comprising the generic public subscription identifiers of the related roaming user equipment that are received by the multicast broadcast session management function: from a network exposure function using one of a message to create a multicast / broadcast services session or a message to modify a multicast / broadcast services session; or from a unified data management in the visiting public land mobile network using a message to provide parameters related to the multicast / broadcast services session.

4. An apparatus, comprising means for performing:receiving, by a session management function in a visiting public land mobile network for roaming user equipment from an access and mobility management function in the visiting public land mobile network, an indication that a roaming user equipment wants to join a multicast / broadcast services session;sending, by the session management function to a multicast broadcast session management function in the visiting public land mobile network, a request for information about the multicast / broadcast services session;receiving, by the session management function from the multicast broadcast session management function in the visiting public land mobile network, at least one of one or more identifiers of user equipment authorized to access the multicast / broadcast services session or information about multicast / broadcast services assistance for the multicast / broadcast services session comprising identifiers of related roaming user equipment;performing, by the session management function, an authorization check to determine whether the roaming user equipment is authorized to access the multicast / broadcast services session; andsending, by the session management function to the access and mobility management function, a response to the indication that the roaming user equipment wants to join the multicast / broadcast services session indicating the user equipment is authorized to join the multicast / broadcast services session.

5. The apparatus according to claim 4, wherein the one or more identifiers comprise subscription permanent identifiers.

6. The apparatus according to claims 4 or 5, wherein the authorization check to determine whether the roaming user equipment that wants to join the multicast / broadcast services session is authorized to access the multicast / broadcast services session considers whether the one of one or more received identifiers of roaming user equipment authorized to access the multicast / broadcast services session comprises an identifier of the roaming user equipment received in the indication.

7. The apparatus according to any of claims 4 to 6, wherein the response to the indicationthat the roaming user equipment wants to join the multicast / broadcast services session comprises multicast / broadcast services assistance information for the multicast / broadcastservices session based on the received identifiers of roaming user equipment related to the information of multicast / broadcast services assistance comprising the identifiers of the roaming user equipment that want to join the multicast / broadcast services session.

8. An apparatus, comprising means for performing:receiving, at a network exposure function from an application function, a message to create or modify a multicast / broadcast services session, comprising an identification of the multicast / broadcast services session, and at least one of generic public subscription identifiers of roaming user equipment authorized to access a multicast / broadcast services session, or information for multicast / broadcast services assistance for the multicast / broadcast services session related to roaming user equipment; andforwarding, from the network exposure function to a multicast broadcast session management function in a visiting public land mobile network of the roaming user equipment, the message.

9. An apparatus, comprising means for performing:receiving, at a unified data management in a visiting public land mobile network of roaming user equipment, a request to store information related to a multicast / broadcast services session comprising an identifier of the multicast / broadcast services session and at least one of one or more identifiers corresponding to one or more user equipment authorized to access the multicast / broadcast services session, and information about multicast / broadcast services assistance for the multicast / broadcast services session comprising identifiers of related user equipment;determining, by the unified data management, inbound roaming user equipment out of at 1 east one of the one or more user equipment authorized to access the multicast / broadcast services session and the user equipment related to the information about multicast / broadcast services assistance; andsending, by the unified data management, a request to store information related to the multicast / broadcast services session to a multicast broadcast session management function or unified data repository, the request comprising the identifier of the multicast / broadcast services session and at least one of the identifiers corresponding to the determined inbound roaming user equipment authorized to access the multicast / broadcast services session, and information about multicast / broadcast services assistance for the multicast / broadcast services session comprising identifiers of the determined inbound roaming user equipment.

10. An apparatus, comprising means for performing:storing, at a unified data repository in a visiting public land mobile network of roaming user equipment, an identifier of a multicast / broadcast services session and at least one of one or more identifiers corresponding to one or more roaming user equipment authorized to access the multicast / broadcast services session, or information about multicast / broadcast services assistance for the multicast / broadcast services session comprising identifiers of related roaming user equipment;receiving, by the unified data repository from a session management function in the visiting public land mobile network, a request for a subscription for the multicast / broadcast services session and comprising a session identification for the multicast / broadcast services session; andsending, by the unified data repository to the session management function using the stored information and in response to the request, at least one of the one or more identifiers of the roaming user equipment authorized to access the multicast / broadcast services session corresponding to the session identification and information about multicast / broadcast services assistance for the multicast / broadcast services session comprising the identifiers of the related roaming user equipment.

11. The apparatus according to claim 10, wherein:the one or more identifiers comprise subscription permanent identifiers;the means are further configured for performing:receiving, by the unified data repository, an identification of the multicast / broadcast services session, and at least one of a generic public subscription identifiers of the roaming user equipment authorized to access the multicast / broadcast services session and information about multicast / broadcast services assistance for the multicast / broadcast services session comprising the generic public subscription identifiers of the related roaming user equipment;sending, by the unified data repository to a unified data management in a home public land mobile network, a request to convert the generic public subscription identifiers of selected one or more user equipment to subscription permanent identifiers; andreceiving, by the unified data repository from the unified data management in the home public land mobile network, subscription permanent identifiers corresponding to the selected one or more user equipment to be used in the sending the one or more identifiers of user equipment; andthe storing comprises storing the subscription permanent identifiers corresponding to the selected one or more user equipment.

12. An apparatus, comprising means for performing:receiving, by a session management function in a visiting public land mobile network of roaming user equipment and from an access and mobility management function in the visiting public land mobile network, an indication that a roaming user equipment wants to join a multicast / broadcast services session;sending, by the session management function to a unified data repository in the visiting public land mobile network, a request for a subscription for information related to the multicast / broadcast services session and comprising a session identification for the multicast / broadcast services session;receiving, by the session management function and from a unified data repository in the visiting public land mobile network and in response to the request, information comprising at least one of one or more identifiers of roaming user equipment authorized to access the multicast / broadcast services session corresponding to the session identification or information about multicast / broadcast services assistance for the multicast / broadcast services session comprising identifiers of related roaming user equipment;performing, by the session management function, an authorization check for the roaming user equipment to see if the roaming user equipment is authorized to access the multicast / broadcast services session; andsending, by the session management function to the access and mobility management function, a response to the indication that a roaming user equipment wants to join a multicast / broadcast services session, information for multicast / broadcast services assistance indicating the user equipment is authorized to join the multicast / broadcast services session.

13. The apparatus according to claim 12, wherein the authorization check to determine whether the roaming user equipment that wants to join the multicast / broadcast services session is authorized to access the multicast / broadcast services session considers whether the one of one or more identifiers of roaming user equipment authorized to access the multicast / broadcast services session comprises the identifier of the roaming user equipment.

14. The apparatus according to any of claims 12 to 13, wherein the response to the indication that the roaming user equipment wants to join the multicast / broadcast services session comprises multicast / broadcast services assistance information for the multicast / broadcast services session based on received identifiers of roaming user equipment related to the information of multicast / broadcast services assistance comprising the received identifiers of the roaming user equipment that want to join the multicast / broadcast services session.

15. An apparatus, comprising means for performing:receiving, at a unified data management in a home public land mobile network for roaming user equipment from a network exposure function in the home public land mobile network or an unified data management in an visiting public land mobile network, a request for storing information related to a multicast / broadcast services session, the request comprising an identification of the multicast / broadcast services session, and at least one of generic public subscription identifiers of roaming user equipment authorized to access the multicast / broadcast services session, information for multicast / broadcast services assistance comprising generic public subscription identifiers of related roaming user equipment, a visiting public land mobile network identification, and a service class;checking, by the unified data management for individual received generic public subscription identifiers of a roaming user equipment, whether that roaming user equipment is authorized to access a multicast / broadcast services service for the multicast / broadcast services session using at least one of the received visiting public land mobile network identification, the received service class, stored information whether the user equipment is entitled to receive multicast / broadcast services when roaming, stored information about visiting public land mobile networks from which the user equipment is entitled to receive multicast / broadcast services when roaming, or stored information about service classes of multicast / broadcast services that the user equipment is entitled to receive when roaming; andstoring, by the unified data management for individual ones of those roaming user equipment that are authorized to receive the multicast / broadcast services service in the visiting public land mobile network, at least one of the identification of an authorized multicast / broadcast services session corresponding to the multicast / broadcast services service or information for multicast / broadcast services assistance for the multicast / broadcast services session.

16. The apparatus according to claim 15, wherein the stored information comprises at least one of the identification of the authorized multicast / broadcast services service and information for multicast / broadcast services assistance related to a roaming user equipment is identified using subscription permanent identifiers of the roaming user equipment and wherein the means are further configured for performing: mapping, by the unified data management, the generic public subscription identifiers of roaming user equipment authorized to access the multicast / broadcast services session to subscription permanent identifiers so the subscription permanent identifiers are then stored corresponding to the roaming user equipment authorized to access the multicast / broadcast services session.

17. The apparatus according to any one of claims 15 or 16, wherein the means are further configured for performing: receiving, by the unified data management from a session management function in the visiting public land mobile network, a request with an identifier of a roaming user equipment; andsending, from the unified data management to the session management function, a response, to the request with an identifier of a roaming user equipment, with stored information comprising at least one of the identifications of the authorized multicast / broadcast services sessions and information for multicast / broadcast services assistance for multicast / broadcast services sessions.

18. An apparatus, comprising means for performing:identifying, at an application function providing data for a multicast / broadcast services session in a public land mobile network, user equipment authorized to participate in the multicast / broadcast services session that have a different public land mobile network as home public land mobile network and their home public land mobile network; andsending, from the application function towards a network exposure function in the home public land mobile network, a request to provision data for the multicast / broadcastservices session, the request comprising at least one of an identification of the multicast / broadcast services session, and at least one of generic public subscription identifiers of roaming user equipment from the home public land mobile network authorized to access the multicast / broadcast services session, information for multicast / broadcast services assistance comprising generic public subscription identifiers of related roaming user equipment from the home public land mobile network, public land mobile network identification of the public land mobile network where the multicast / broadcast services session is provided, and a service class.

19. An apparatus, comprising means for performing:receiving, at an unified data management in a public land mobile network where a multicast / broadcast services session is provided from a network exposure function in the public land mobile network a request to provision data for the multicast / broadcast services session, the request comprising at least one of an identification of the multicast / broadcast services session, and at least one of generic public subscription identifiers of user equipment authorized to access the multicast / broadcast services session, information for multicast / broadcast services assistance comprising generic public subscription identifiers of related user equipment, or a service class;identifying, at the unified data management, generic public subscription identifiers of user equipment that have a different public land mobile network as home public land mobile network and their home public land mobile network; andsending, from the unified data management in the public land mobile network towards a unified data management in the home public land mobile network a request to provision data for the multicast / broadcast services session, the request comprising an identification of the multicast / broadcast services session, and at least one of generic public subscription identifiers of roaming user equipment from the home public land mobile network authorized to access the multicast / broadcast services session, information for multicast / broadcast services assistance comprisinggeneric public subscription identifiers of related roaming user equipment from the home public land mobile network, public land mobile network identification of the public land mobile network where the multicast / broadcast services session is provided, or a service class.

20. An apparatus, comprising means for performing:receiving, at an unified data management in a public land mobile network where a multicast / broadcast services session is provided from a network exposure function in the public land mobile network, a request to provision data for the multicast / broadcast services session, the request comprising at least one of an identification of the multicast / broadcast services session, and at least one of generic public subscription identifiers of user equipment authorized to access the multicast / broadcast services session, or information for multicast / broadcast services assistance comprising generic public subscription identifiers of related user equipment;identifying, at the unified data management, generic public subscription identifiers of user equipment that have a different public land mobile network as home public land mobile network and their home public land mobile network;sending, for individual identified user equipment, from the unified data management in the public land mobile network towards a unified data management in the home public land mobile network of the identified user equipment, a request to provision identifiers of session management functions handling the identified user equipment, the request comprising the generic public subscription identifiers of the identified user equipment;receiving, for individual identified user equipment, at the unified data management in the public land mobile network from the unified data management in the home public land mobile network of the identified user equipment, a 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; andsending, for individual identified user equipment, from the unified data management in the public land mobile network towards the session management function, a request to provision data for the multicast / broadcast services session, the request comprising an identification of the multicast / broadcast services session, and at 1 east one of the subscription permanent identifier of the identified roaming user equipment to indicate that the identified roaming user equipment is authorized to access the multicast / broadcast services session, or information for multicast / broadcast services assistance comprising subscription permanent identifier of the identified roaming user equipment.

21. An apparatus, comprising means for performing:receiving, by a session management function in an visiting public land mobile network of roaming user equipment from a unified data management in the visiting public land mobile network, a request to provision data for a multicast / broadcast services session, the request comprising an identification of the multicast / broadcast services session, and at least one of a subscription permanent identifier of a roaming user equipment to indicate that it is authorized to access the multicast / broadcast services session, and information for multicast / broadcast services assistance comprising subscription permanent identifier of a roaming user equipment;storing, by the session management function the received identification of the multicast / broadcast services session, and at least one of the received subscription permanent identifier of a roaming user equipment to indicate that it is authorized to access the multicast / broadcast services session, or the received information for multicast / broadcast services assistance comprising subscription permanent identifier of a roaming user equipment;receiving, by the session management function from an access and mobility management function in the visiting public land mobile network, an indication that a roaming user equipment wants to join the multicast / broadcast services session;performing, by the session management function, an authorization check to determine whether the roaming user equipment is authorized to access the multicast / broadcast services session; andsending, by the session management function to the access and mobility management function, a response to the indication that the roaming user equipment wants to join the multicast / broadcast services session indicating the user equipment is authorized to join the multicast / broadcast services session.

22. The apparatus according to claim 21, wherein the authorization check to determine whether the roaming user equipment that wants to join the multicast / broadcast services session is authorized to access the multicast / broadcast services session considers whether stored one or more identifiers of roaming user equipment authorized to access the multicast / broadcast services session comprises the identifier of the roaming user equipment.

23. The apparatus according to any of claims 21 to 22, wherein the response to the indication that the roaming user equipment wants to join the multicast / broadcast services session comprises multicast / broadcast services assistance information for the multicast / broadcast services session if the stored one or more identifiers of roaming user equipment related to the information of multicast / broadcast services assistance comprises the identifiers of the roaming user equipment that want to join the multicast / broadcast services session.

24. The apparatus of any preceding apparatus claim, wherein the means comprises: at least one processor; andat least one memory storing instructions that, when executed by at least one processor, cause the performance of the apparatus.77

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