Support of multicast and broadcast system services from public land mobile networks through roaming user equipment using separate delivery

Abstract

Systems, methods, apparatuses, and computer program products for supporting multicast services. A method may include receiving, by a home session management function (H-SMF) from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in the VPLMN to join a multicast multicast and broadcast service (MBS) session; and determining, by the H-SMF, whether the UE is authorized to join a multicast MBS session. The determination is based on at least one of a local configuration in the home public land mobile network, information received from an application function during establishment of a multicast MBS session, or user subscription data received from a user data manager. The method also performs at least one of transmitting, by the H-SMF to the V-SMF, an acceptance response configured to establish at least one unicast quality of service (QoS) flow corresponding to multicast QoS flow information received from a home multicast / broadcast session management function (H-MB-SMF) based on a determination that the UE is authorized to join the multicast MBS session, or based on determining that the UE is not authorized to join the multicast MBS session, sending, by the H-SMF, a rejection response to the V-SMF, the rejection response comprising: error cause information indicating that the UE is not authorized to join the multicast MBS session while roaming.

Description

Technical Field

[0001] Some example embodiments generally relate to mobile or wireless telecommunication systems, such as 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), fifth generation (5G) radio access technology (RAT), new radio (NR) access technology, sixth generation (6G), and / or other communication systems. For example, certain example embodiments may relate to systems and / or methods for supporting multicast services. Background Art

[0002] Examples of mobile or wireless telecommunication systems may include radio frequency (RF) 5G RAT, Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), LTE Evolved UTRAN (E-UTRAN), LTE-Advanced (LTE-A), LTE-APro, NR access technology, and / or MulteFire Alliance. 5G wireless systems refer to next generation (NG) radio systems and network architectures. 5G systems are typically built on 5G NR, but 5G (or NG) networks can also be built on E-UTRA radios. It is expected that NR can support service categories such as enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC), and massive machine type communications (mMTC). NR is expected to provide ultra-wideband, ultra-robust, low-latency connections, and large-scale networks to support the Internet of Things (IoT). The next generation radio access network (NG-RAN) represents a radio access network (RAN) for 5G, which can provide radio access for NR, LTE, and LTE-A. Note that a node in 5G that provides radio access functionality to user equipment (e.g., similar to a Node B in UTRAN or an evolved Node B (eNB) in LTE) may be referred to as a next-generation Node B (gNB) when built on an NR radio, and may be referred to as a next-generation eNB (NG-eNB) when built on an E-UTRA radio. Summary of the invention

[0003] According to some example embodiments, a method may include receiving, by a home session management function (H-SMF), from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in the VPLMN to join a multicast multicast and broadcast service (MBS) session. The method may also include determining, by the H-SMF, whether the UE is authorized to join the multicast MBS session. The determination is based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager. The method may also include performing at least one of the following: based on determining that the UE is authorized to join the multicast MBS session, the H-SMF sends an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, the H-SMF sends a rejection response to the V-SMF, the rejection response including: error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming.

[0004] According to certain example embodiments, an apparatus may include: means for receiving, from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in the VPLMN to join a multicast multicast and broadcast service (MBS) session. The apparatus may also include means for determining whether the UE is authorized to join the multicast MBS session. The determination is based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager. The apparatus may also include a component for performing at least one of the following: based on determining that the UE is authorized to join the multicast MBS session, sending an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, sending a rejection response to the V-SMF, the rejection response including error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming.

[0005] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include receiving, from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in a VPLMN to join a multicast multicast and broadcast service (MBS) session. The method may also include determining whether the UE is authorized to join the multicast MBS session. The determination is based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager. The method may also include performing at least one of the following: based on determining that the UE is authorized to join the multicast MBS session, sending an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, sending a rejection response to the V-SMF, the rejection response including: error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming.

[0006] According to some example embodiments, a computer program product may perform a method. The method may include receiving, from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in the VPLMN to join a multicast multicast and broadcast service (MBS) session. The method may also include determining whether the UE is authorized to join the multicast MBS session. The determination is based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager. The method may also include performing at least one of the following: based on determining that the UE is authorized to join the multicast MBS session, sending an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, sending a rejection response to the V-SMF, the rejection response including: error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming.

[0007] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receive, from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in the VPLMN to join a multicast multicast and broadcast service (MBS) session. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least determine whether the UE is authorized to join the multicast MBS session. The determination is based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager. When executed by at least one processor, the at least one memory and the instructions may further cause the apparatus to perform at least one of the following: based on determining that the UE is authorized to join the multicast MBS session, sending an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, sending a rejection response to the V-SMF, the rejection response including error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming.

[0008] According to various example embodiments, an apparatus may include receiving circuitry configured to perform: receiving, from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in a VPLMN to join a multicast multicast and broadcast service (MBS) session. The apparatus may also include determining circuitry configured to perform determining whether the UE is authorized to join the multicast MBS session. The determination is based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager. The device may also include a sending circuit system configured to perform: based on determining that the UE is authorized to join the multicast MBS session, sending an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, sending a rejection response to the V-SMF, the rejection response including: error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming.

[0009] According to some example embodiments, a method may include: receiving, by a visited session management function (V-SMF), a join request from a UE requesting the UE to join a multicast MBS session. The method may also include: determining, by the V-SMF, that the PDU session associated with the join request is toward a home routing PDU session of an H-SMF. The method may also include: sending a join request to the identified H-SMF based on the determination. The method may also include: receiving, by the V-SMF, at least one of an acceptance response or a rejection response to a join request including a request to establish at least one unicast QoS flow. The method may also include: sending, by the V-SMF, a response to the join request toward the UE.

[0010] According to certain example embodiments, an apparatus may include: a component for receiving a join request from a UE requesting the UE to join a multicast MBS session. The apparatus may also include: a component for determining that a protocol data unit (PDU) session associated with the join request is toward a home routed PDU session of a home session management function (H-SMF). The apparatus may also include: a component for sending a join request to an identified H-SMF based on the determination. The apparatus may also include: a component for receiving at least one of an acceptance response or a rejection response to a join request including a request to establish at least one unicast QoS flow. The apparatus may also include: a component for sending a response to the join request to the UE.

[0011] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include: receiving a join request from a UE requesting the UE to join a multicast MBS session. The method may also include determining that a protocol data unit (PDU) session associated with the join request is toward a home-routed PDU session of a home session management function (H-SMF). The method may also include: based on the determination, sending a join request to the identified H-SMF. The method may also include receiving at least one of an acceptance response or a rejection response to a join request including a request to establish at least one unicast QoS flow. The method may also include: sending a response to the join request to the UE.

[0012] According to some example embodiments, a computer program product may perform a method. The method may include: receiving a join request from a UE requesting the UE to join a multicast MBS session. The method may also include determining that a protocol data unit (PDU) session associated with the join request is toward a home routed PDU session of a home session management function (H-SMF). The method may also include: based on the determination, sending a join request to the identified H-SMF. The method may also include: receiving at least one of an acceptance response or a rejection response to the join request including a request to establish at least one unicast QoS flow. The method may also include: sending a response to the join request to the UE.

[0013] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions, which instructions, when executed by the at least one processor, cause the apparatus to at least: receive a join request from a UE requesting the UE to join a multicast MBS session. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: determine that a protocol data unit (PDU) session associated with the join request is toward a home routed PDU session of a home session management function (H-SMF). The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: send the join request to the identified H-SMF based on the determination. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: receive at least one of an acceptance response or a rejection response to the join request, the acceptance response including a request to establish at least one unicast QoS flow. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: send a response to the join request to the UE.

[0014] According to various example embodiments, an apparatus may include a receiving circuit system configured to perform: receiving a join request from a UE requesting the UE to join a multicast MBS session. The apparatus may also include a determining circuit system configured to perform: determining that a protocol data unit (PDU) session associated with the join request is toward a home routed PDU session of a home session management function (H-SMF). The apparatus may also include a sending circuit system configured to perform: sending a join request to an identified H-SMF based on the determination. The apparatus may also include a receiving circuit system configured to perform: receiving at least one of an acceptance response or a rejection response to the join request, the acceptance response including a request to establish at least one unicast QoS flow. The apparatus may also include a sending circuit system configured to perform: sending a response to the join request to the UE.

[0015] According to some example embodiments, a method may include: receiving, by a NG RAN node, signaling to establish at least one unicast QoS flow to a UE, wherein the signaling indicates, for the at least one unicast QoS flow, that it is related to an MBS multicast session and indicates at least one of: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of the UE. The method may also include: configuring at least one radio bearer to send the at least one unicast QoS flow to the UE. The method may also include: storing the received indication for the at least one unicast QoS flow in a multicast MBS session context.

[0016] According to certain example embodiments, an apparatus may include means for receiving signaling to establish at least one unicast QoS flow to a UE, wherein the signaling indicates for the at least one unicast QoS flow that it is related to an MBS multicast session and indicates at least one of: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of the UE. The apparatus may also include means for configuring at least one radio bearer to send the at least one unicast QoS flow to the UE. The apparatus may also include means for storing the received indication for the at least one unicast QoS flow in a multicast MBS session context.

[0017] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include receiving signaling to establish at least one unicast QoS flow to a UE, wherein the signaling indicates for the at least one unicast QoS flow that it is related to an MBS multicast session and indicates at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of the UE. The method may also include configuring at least one radio bearer to send at least one unicast QoS flow to the UE. The method may also include storing the received indication for at least one unicast QoS flow in a multicast MBS session context.

[0018] According to some example embodiments, a computer program product may perform a method. The method may include: receiving signaling to establish at least one unicast QoS flow to a UE, wherein the signaling indicates for the at least one unicast QoS flow that it is related to an MBS multicast session and indicates at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of the UE. The method may also include configuring at least one radio bearer to send the at least one unicast QoS flow to the UE. The method may also include: storing the received indication for the at least one unicast QoS flow in a multicast MBS session context.

[0019] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions, which instructions, when executed by the at least one processor, cause the apparatus to at least: receive signaling to establish at least one unicast QoS flow to a UE, wherein the signaling indicates for the at least one unicast QoS flow that it is related to an MBS multicast session and indicates at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of the UE. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: configure at least one radio bearer to send the at least one unicast QoS flow to the UE. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: send a response to a join request to the UE.

[0020] According to various example embodiments, an apparatus may include a receiving circuit system configured to perform: receiving signaling to establish at least one unicast QoS flow to a UE, wherein the signaling indicates for the at least one unicast QoS flow that it is related to an MBS multicast session and indicates at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of the UE. The apparatus may also include a configuration circuit system configured to perform: configuring at least one radio bearer to send at least one unicast QoS flow to the UE. The apparatus may also include a sending circuit system configured to perform: sending, by the V-SMF, a response to a join request to the UE.

[0021] According to some example embodiments, a method may include: receiving, by a home session management function (H-SMF), a join request requesting a UE to join a multicast MBS session. The method may also include: receiving, by the H-SMF, an N2SM container switching requirement transfer information element from a V-SMF in a first VPLMN, the N2SM container switching requirement transfer information element including multicast MBS session information of at least one MBS session that the UE has joined. The method may also include: determining, by the H-SMF, when the UE is roaming in the first VPLMN, whether the UE is authorized to continue receiving the multicast MBS session. The determination is based on at least one of the following: local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager.

[0022] According to certain example embodiments, an apparatus may include: a component for receiving a join request requesting a UE to join a multicast MBS session. The apparatus may also include: a component for receiving an N2SM container switching requirement transfer information element from a V-SMF in a first VPLMN, the N2SM container switching requirement transfer information element including multicast MBS session information of at least one MBS session that the UE has joined. The apparatus may also include: a component for determining whether the UE is authorized to continue receiving the multicast MBS session when the UE is roaming in the first VPLMN. The determination is based on at least one of the following: local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager.

[0023] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include: receiving a join request requesting a UE to join a multicast MBS session. The method may also include: receiving an N2SM container switching requirement transfer information element from a V-SMF in a first VPLMN, the N2SM container switching requirement transfer information element including: multicast MBS session information of at least one MBS session that the UE has joined. The method may also include: determining whether the UE is authorized to continue receiving the multicast MBS session when the UE roams in the first VPLMN. The determination is based on at least one of the following: local configuration in the home public land mobile network, information received from an application function during establishment of a multicast MBS session, or user subscription data received from a user data manager.

[0024] According to some example embodiments, a computer program product may perform a method. The method may include: receiving a join request requesting a UE to join a multicast MBS session. The method may also include: receiving an N2SM container switching requirement transfer information element from a V-SMF in a first VPLMN, the N2SM container switching requirement transfer information element including multicast MBS session information of at least one MBS session that the UE has joined. The method may also include: when the UE roams in the first VPLMN, determining whether the UE is authorized to continue receiving the multicast MBS session. The determination is based on at least one of the following: local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager.

[0025] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions, which instructions, when executed by the at least one processor, cause the apparatus to at least: receive a join request requesting a UE to join a multicast MBS session. The at least one memory and the instructions, when executed by the at least one processor, may further cause the apparatus to at least: receive an N2SM container switching requirement transfer information element from a V-SMF in a first VPLMN, the N2SM container switching requirement transfer information element including multicast MBS session information of at least one MBS session that the UE has joined. The at least one memory and the instructions, when executed by the at least one processor, may further cause the apparatus to at least: determine whether the UE is authorized to continue receiving the multicast MBS session when the UE roams in the first VPLMN. The determination is based on at least one of the following: local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager.

[0026] According to various example embodiments, an apparatus may include a receiving circuit system configured to perform: receiving a join request requesting a UE to join a multicast MBS session. The apparatus may also include a receiving circuit system configured to perform receiving an N2SM container switching requirement transfer information element from a V-SMF in a first VPLMN, the N2SM container switching requirement transfer information element including: multicast MBS session information of at least one MBS session that the UE has joined. The apparatus may also include a determining circuit system configured to perform: when the UE roams in the first VPLMN, determining whether the UE is authorized to continue receiving the multicast MBS session. The determination is based on at least one of the following: local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager.

[0027] According to some example embodiments, a method may include: receiving, by a visited session management function (V-SMF), a handover requirement delivery information element for a home routing PDU session anchored at an H-SMF from an AMF. The method may also include sending a handover requirement delivery information element to an identified H-SMF. The method may also include: receiving, by the V-SMF, in response to sending the handover requirement delivery information element to the H-SMF, a reply message including at least one of the following: indicating to the UE a request for the UE to be removed from the MBS multicast session, or establishing a configuration for at least one unicast QoS flow.

[0028] According to certain example embodiments, an apparatus may include: a component for receiving a handover requirement delivery information element for a home routing PDU session anchored at an H-SMF from an AMF. The apparatus may also include: a component for sending a handover requirement delivery information element to an identified H-SMF. The apparatus may also include: a component for receiving a reply message in response to sending the handover requirement delivery information element to the H-SMF, the reply message including at least one of the following: a request to indicate to the UE that the UE is removed from the MBS multicast session, or a configuration to establish at least one unicast QoS flow.

[0029] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include: receiving a handover requirement transfer information element for a home routing PDU session anchored at an H-SMF from an AMF. The method may also include: sending a handover requirement transfer information element to an identified H-SMF. The method may also include: in response to sending a handover requirement transfer information element to the H-SMF, receiving a reply message including at least one of the following: indicating to the UE a request to be removed from the MBS multicast session, or establishing a configuration for at least one unicast QoS flow.

[0030] According to some example embodiments, a computer program product may perform a method. The method may include: receiving a handover requirement delivery information element for a home routing PDU session anchored at an H-SMF from an AMF. The method may also include: sending a handover requirement delivery information element to an identified H-SMF. The method may also include: in response to sending the handover requirement delivery information element to the H-SMF, receiving a reply message including at least one of the following: indicating to the UE a request to be removed from the MBS multicast session, or establishing a configuration of at least one unicast QoS flow.

[0031] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions, which instructions, when executed by the at least one processor, cause the apparatus to at least: receive a handover requirement transfer information element for a home routing PDU session anchored at an H-SMF from an AMF. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: send a handover requirement transfer information element to an identified H-SMF. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: in response to sending the handover requirement transfer information element to the H-SMF, receive a reply message including at least one of the following: a request to indicate to the UE that the UE is removed from the MBS multicast session, or a configuration to establish at least one unicast QoS flow.

[0032] According to various example embodiments, an apparatus may include a receiving circuit system configured to perform: receiving a handover requirement delivery information element for a home routing PDU session anchored at an H-SMF from an AMF. The apparatus may also include a sending circuit system configured to perform: sending a handover requirement delivery information element to an identified H-SMF. The apparatus may also include a receiving circuit system configured to perform: in response to sending the handover requirement delivery information element to the H-SMF, receiving a reply message including at least one of the following: indicating to the UE a request to be removed from the MBS multicast session, or establishing a configuration of at least one unicast QoS flow.

[0033] According to some example embodiments, a method may include: sending, by a user equipment roaming in a VPLMN, a request to join a multicast MBS session. The method may also include: receiving, by the UE, a join request rejection message indicating that the UE is not allowed to access the MBS session while roaming. The method may also include: suppressing sending additional join requests for the MBS session while roaming.

[0034] According to certain example embodiments, an apparatus may include means for sending a request to join a multicast MBS session. The apparatus may also include means for receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session while roaming. The apparatus may also include means for refraining from sending additional join requests for the MBS session while roaming.

[0035] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include: sending a request to join a multicast MBS session. The method may also include: receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session when roaming. The method may also include: when roaming, refraining from sending additional join requests for the MBS session.

[0036] According to some example embodiments, a computer program product may perform a method. The method may include: sending a request to join a multicast MBS session. The method may also include: receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session when roaming. The method may also include: when roaming, refraining from sending additional join requests for the MBS session.

[0037] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: send a request to join a multicast MBS session. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: receive a join request rejection message indicating that the apparatus is not allowed to access the MBS session when roaming. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: refrain from sending additional join requests for the MBS session when roaming.

[0038] According to various example embodiments, an apparatus may include a sending circuit system configured to perform: sending a request to join a multicast MBS session. The apparatus may also include a receiving circuit system configured to perform: receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session when roaming. The apparatus may also include a suppression circuit system configured to perform: when roaming, suppressing sending additional join requests for the MBS session.

[0039] According to some example embodiments, a method may include: sending, by a user equipment roaming in a VPLMN, a request to join a multicast MBS session. The method may also include: receiving, by the UE, a join request rejection message indicating that the UE is not allowed to access the MBS session when roaming in the VPLMN. The method may also include: suppressing sending additional join requests for the MBS session when roaming in the VPLMN.

[0040] According to certain example embodiments, an apparatus may include means for sending a request to join a multicast MBS session. The apparatus may also include means for receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session while roaming in a VPLMN. The apparatus may also include means for refraining from sending additional join requests for the MBS session while roaming in the VPLMN.

[0041] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include: sending a request to join a multicast MBS session. The method may also include: receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session when roaming in a VPLMN. The method may also include: suppressing sending additional join requests for the MBS session when roaming in a VPLMN.

[0042] According to some example embodiments, a computer program product may perform a method. The method may include: sending a request to join a multicast MBS session. The method may also include: receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session when roaming in a VPLMN. The method may also include: when roaming in a VPLMN, suppressing sending additional join requests for the MBS session.

[0043] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: send a request to join a multicast MBS session. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: receive a join request rejection message indicating that the apparatus is not allowed to access the MBS session when roaming in a VPLMN. The at least one memory and the instructions, when executed by the at least one processor, may additionally cause the apparatus to: at least refrain from sending additional join requests for the MBS session when roaming in the VPLMN.

[0044] According to various example embodiments, an apparatus may include a sending circuit system configured to perform: sending a request to join a multicast MBS session. The apparatus may also include a receiving circuit system configured to perform: receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session when roaming in a VPLMN. The apparatus may also include a suppression circuit system configured to perform: when roaming in a VPLMN, suppressing sending additional join requests for the MBS session.

[0045] According to some example embodiments, a method may include: sending, by a user equipment, a request to join a multicast MBS session. The method may also include: roaming in a VPLMN. The method may also include: receiving, by the UE, an indication that the UE was removed from the MBS session, the indication having a reason indicating that the UE is not allowed to access the MBS multicast session while roaming. The method may also include: while roaming, suppressing sending additional join requests for the MBS multicast session.

[0046] According to certain example embodiments, an apparatus may include means for sending a request to join a multicast MBS session. The apparatus may also include means for roaming in a VPLMN. The apparatus may also include means for receiving an indication that the apparatus is removed from the MBS session, the indication having a reason indicating that the apparatus is not allowed to access the MBS multicast session while roaming. The apparatus may also include means for refraining from sending additional join requests for the MBS multicast session while roaming.

[0047] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include: sending a request to join a multicast MBS session. The method may also include: roaming in a VPLMN. The method may also include: receiving an indication that the apparatus is removed from the MBS session, the indication having a reason indicating that the apparatus is not allowed to access the MBS multicast session while roaming. The method may also include: while roaming, suppressing sending additional join requests for the MBS multicast session.

[0048] According to some example embodiments, a computer program product may perform a method. The method may include: sending a request to join a multicast MBS session. The method may also include: roaming in a VPLMN. The method may also include: receiving an indication that the apparatus is removed from the MBS session, the indication having a reason indicating that the apparatus is not allowed to access the MBS multicast session while roaming. The method may also include: while roaming, refraining from sending additional join requests for the MBS multicast session.

[0049] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: send a request to join a multicast MBS session. The at least one memory and instructions, when executed by the at least one processor, may additionally cause the apparatus to at least roam in a VPLMN. The at least one memory and instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: receive an indication that the apparatus was removed from the MBS session, the indication having a reason that the apparatus was not allowed to access the MBS multicast session while roaming. The at least one memory and instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: refrain from sending additional join requests for the MBS multicast session when roaming.

[0050] According to various example embodiments, an apparatus may include a sending circuit system configured to perform: sending a request to join a multicast MBS session. The apparatus may also include a roaming circuit system configured to perform: roaming in a VPLMN. The apparatus may also include a receiving circuit system configured to perform: receiving an indication that the apparatus is removed from the MBS session, indicating that the apparatus is not allowed to access the MBS multicast session when roaming. The apparatus may also include a reason for suppressing circuit system configured to perform: when roaming, suppressing sending additional join requests for the MBS multicast session.

[0051] According to some example embodiments, a method may include: sending, by a user equipment, a request to join a multicast MBS session. The method may also include: roaming in a VPLMN. The method may also include: receiving, by the UE, an indication that the UE was removed from the MBS session, wherein the indication has a reason that the UE is not allowed to access the MBS multicast session while roaming in the VPLMN. The method may also include: while roaming in the VPLMN, suppressing sending additional join requests for the MBS multicast session.

[0052] According to certain example embodiments, an apparatus may include means for sending a request to join a multicast MBS session. The apparatus may also include means for roaming in a VPLMN. The apparatus may also include means for receiving an indication that the apparatus is removed from the MBS session, the indication having a reason that the apparatus is not allowed to access the MBS multicast session while roaming in the VPLMN. The apparatus may also include means for refraining from sending additional join requests for the MBS multicast session while roaming in the VPLMN.

[0053] According to various example embodiments, a non-transitory computer-readable medium may include program instructions that, when executed by an apparatus, cause the apparatus to perform at least one method. The method may include: sending a request to join a multicast MBS session. The method may also include: roaming in a VPLMN. The method may also include: receiving an indication that the apparatus is removed from the MBS session, the indication having a reason that the apparatus is not allowed to access the MBS multicast session while roaming in the VPLMN. The method may also include: suppressing sending additional join requests for the MBS multicast session while roaming in the VPLMN.

[0054] According to some example embodiments, a computer program product may perform a method. The method may include: sending a request to join a multicast MBS session. The method may also include: roaming in a VPLMN. The method may also include: receiving an indication that the apparatus is removed from the MBS session, the indication having a reason that the apparatus is not allowed to access the MBS multicast session while roaming in the VPLMN. The method may also include: while roaming in the VPLMN, suppressing sending additional join requests for the MBS multicast session.

[0055] According to certain example embodiments, an apparatus may include at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: send a request to join a multicast MBS session. The at least one memory and instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: roam in a VPLMN. The at least one memory and instructions, when executed by the at least one processor, may additionally cause the apparatus to at least: receive an indication that the apparatus was removed from the MBS session, the indication having a reason that the apparatus was not allowed to access the MBS multicast session while roaming in the VPLMN. The at least one memory and instructions, when executed by the at least one processor, may additionally cause the apparatus to: at least refrain from sending additional join requests for the MBS multicast session while roaming in the VPLMN.

[0056] According to various example embodiments, an apparatus may include a sending circuit system configured to perform: sending a request to join a multicast MBS session. The apparatus may also include a roaming circuit system configured to perform: performing roaming in a VPLMN. The apparatus may also include a receiving circuit system configured to perform: receiving an indication that the apparatus is removed from the MBS session, the indication having a reason that the apparatus is not allowed to access the MBS multicast session when roaming in the VPLMN. The apparatus may also include a suppression circuit system configured to perform: when roaming in the VPLMN, suppressing the sending of additional join requests for the MBS multicast session. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] For a proper understanding of the example embodiments, reference should be made to the accompanying drawings, in which:

[0058] Figures 1A-1C illustrates an example of a signaling diagram for a UE joining process in a VPLMN for a multicast MBS service provided by a HPLMN in accordance with certain example embodiments;

[0059] Figures 2A-2C illustrates an example of a signaling diagram when a UE that has joined a multicast MBS session in the HPLMN is moving from the HPLMN to the VPLMN and the UE is authorized to continue receiving the multicast MBS session according to various example embodiments;

[0060] Figures 3A-3D illustrates an example of a signaling diagram when a UE that has joined a multicast MBS session in the HPLMN is moving from the HPLMN to the VPLMN and the UE is not authorized to continue receiving the multicast MBS session according to various example embodiments;

[0061] Figure 4 illustrates a flowchart example of a method according to certain example embodiments;

[0062] Figure 5 illustrates a flowchart example of a method according to some example embodiments;

[0063] Figure 6 illustrates a flowchart example of a method according to various example embodiments;

[0064] Figure 7 illustrates a flowchart example of a method according to certain example embodiments;

[0065] Figure 8 illustrates a flowchart example of a method according to some example embodiments;

[0066] Fig. 9 illustrates a flowchart example of a method according to various example embodiments;

[0067] Fig.10 illustrates a flowchart example of a method according to certain example embodiments;

[0068] Fig.11 illustrates a flowchart example of a method according to some example embodiments;

[0069] Fig.12 illustrates a flowchart example of a method according to some example embodiments;

[0070] Fig.13 illustrates examples of various network devices according to some example embodiments;

[0071] Fig.14 An example of a 5G network and system architecture is illustrated in accordance with certain example embodiments.

[0072] Specific implementation

[0073] It is readily understood that the components of certain example embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of some example embodiments of systems, methods, apparatuses, and computer program products for supporting multicast services is not intended to limit the scope of certain example embodiments, but rather represents selected example embodiments.

[0074] Currently, Multicast and Broadcast System (MBS) services do not support roaming, but 3GPP Rel-19 is expected to add support for MBS services for roaming UEs. The Home Session Management Function (H-SMF) of the Home Public Land Mobile Network (HPLMN) may perform authorization checks on UEs joining or leaving a multicast session provided by the HPLMN. When a UE roams from its HPLMN to a Visited PLMN (VPLMN) and attempts to join or leave a multicast MBS session provided by its HPLMN, the Visited SMF (V-SMF) of the VPLMN may receive a UE Join or Leave message, which may not be aware of the roaming outbound restrictions in the HPLMN. Therefore, such authorization checks cannot currently be performed.

[0075] In addition, due to UE mobility (i.e., inter-PLMN handover or registration), the UE may successfully join the multicast MBS service in its HPLMN and roam to the VPLMN. However, the multicast MBS service of its HPLMN that the UE has joined may or may not be authorized in the VPLMN. As a result, when the UE is authorized to continue to receive multicast MBS traffic in the VPLMN, there is currently no suitable architecture defined to continue to support multicast MBS sessions in the VPLMN. Similarly, when the UE is not authorized to continue to receive multicast MBS traffic in the VPLMN, there is no suitable architecture to prevent the UE from receiving multicast MBS services in the VPLMN.

[0076] Certain example embodiments described herein may have various benefits and / or advantages to overcome the above disadvantages. For example, certain example embodiments may provide a roaming authorization check to support the process of a UE joining and leaving a handover multicast MBS session provided by its HPLMN when the UE is within a VPLMN, or roaming to a VPLMN. Some example embodiments may introduce architectural changes required to support multicast MBS services in roaming scenarios of inter-PLMN mobility, where current architectures do not support these scenarios, and / or may reuse some existing architectures to improve compatibility. Therefore, certain example embodiments discussed below are directed to improvements in computer-related technologies.

[0077] Although the various embodiments provided herein relate to PLMNs, any such embodiments may also be applicable to roaming between independent non-public networks (SNPNs). In certain example embodiments, for a UE roaming from an HPLMN to a VPLMN (i.e., inter-PLMN mobility), the UE wants to receive a multicast MBS service provided by the HPLMN in the VPLMN, and the shared MBS traffic delivery may not be used for the MBS service in the VPLMN, but may use MBS separate traffic delivery. In addition, a home routing protocol data unit (PDU) session architecture may be used, in which the V-SMF communicates with the H-SMF for PDU session operations. During the establishment of a home routing PDU session, or during the insertion or change of the V-SMF, an N9 (e.g., general packet radio traffic tunneling protocol (GTP)-U) tunnel may be established between the new V-UPF and the H-UPF. In addition, the H-SMF may act as a network function that interacts with the H-MB-SMF that provides MBS services, and the H-MB-SMF may act as a network function that interacts with the H-MB-UPF. In this way, MBS data can flow from the home multicast / broadcast session management function (H-MB-UPF) to the home user plane function (H-UPF) (e.g., controlled by the H-SMF), from the H-UPF to the visited user location function (V-UPF) (e.g., controlled by the V-SMF), and then to the gNB serving the UE.

[0078] In various example embodiments, a UE roaming in a VPLMN may want to join a multicast MBS service provided by the HPLMN (i.e., an outbound roamer). For example, the UE may trigger a join request (i.e., a PDU session modification process or a PDU session establishment process) to the V-SMF in the VPLMN to join a multicast MBS session. An MBS-related request from a UE in the VPLMN (e.g., joining a new multicast MBS session) may require a new signal to be sent from the V-SMF to the H-SMF and a response in the opposite direction. The V-SMF may determine whether to forward the join request to the H-SMF or process the request itself based on the PDU session used by the UE. For example, for a locally routed PDU session, a multicast MBS service may be provided by the HPLMN, so the H-SMF may be contacted. Similarly, for a locally routed PDU session, a multicast MBS service may be provided by the VPLMN. In the case of contacting the H-SMF, the H-SMF may then contact the H-MB-SMF to obtain multicast MBS service-related information, including multicast quality of service (QoS) flow information.

[0079] The H-SMF may then check whether the roaming UE is authorized to join the multicast MBS service provided by the HPLMN while the UE is roaming in that specific VPLMN (i.e., outbound roamer) or in general any VPLMN. Information about the multicast roaming authorization may be pre-configured in the HPLMN, or may be provided by the Application Function (AF) (e.g., when establishing an MBS session), or may be obtained from the Unified Data Manager (UDM) (e.g., from user subscription data).

[0080] In certain example embodiments, if the roaming UE is not authorized to join the multicast MBS service in the VPLMN, the H-SMF may refuse to return the multicast join request to the V-SMF (e.g., indicating a reason that the UE is not authorized to join the MBS session from the VPLMN or any VPLMN), and the V-SMF may refuse to return the request to the UE (e.g., when sending an error reason raised by the H-SMF). Based on the received reason, the UE may not request to join in the future if it is in the same VPLMN and / or from any VPLMN.

[0081] In some other example embodiments, if the roaming UE is authorized to join the multicast MBS service in the VPLMN, the H-SMF may prepare for separate MBS delivery from the H-MB-UPF to the H-UPF (i.e., the Protocol Data Unit Session Anchor (PSA) UPF) (e.g., even if MBS shared traffic delivery is used in the HPLMN for the multicast MBS service), and may map the information about the multicast QoS flows received from the H-MB-SMF to the unicast QoS flow information of the PDU session. The H-SMF may signal these unicast QoS flows to the V-SMF in a response to the V-SMF and / or in a subsequent PDU session modification request to the V-SMF.

[0082] Once the H-SMF signals the V-SMF about these unicast QoS flows, the H-SMF may respond to the V-SMF indicating acceptance of the multicast join request. For example, the H-SMF may respond while maintaining VPLMN agnosticism of the MBS session / multicast MBS flow associated with the PDU session. Specifically, the H-SMF may request the V-SMF to establish unicast QoS flows (e.g., associated with MBS services) without indicating that they are associated with multicast MBS services / multicast QoS flows. In this way, the response may be passed from the V-SMF to the V-AMF, and from the V-AMF to the V-NG-RAN, without an indication in the N2 message that the new QoS flow is also associated with the multicast MBS service. Therefore, the VPLMN may not be aware that the unicast QoS flow for the MBS service is associated with the MBS service, and therefore, the VPLMN's NG-RAN may also not be aware and not attempt to establish shared delivery. The VPLMN may then treat the unicast QoS flow like a regular / non-MBSQoS flow for the PDU session. The VPLMN (eg, V-SMF and V-NG-RAN) may treat unicast QoS flows like regular / non-MBS QoS flows and may not request establishment of shared delivery.

[0083] In another example, the H-SMF may respond if the VPLMN is aware of the MBS session / multicast MBS flow associated with the PDU session. For example, in addition to requesting a new unicast QoS flow, as described above, the H-SMF may also include a new indication in the response to the V-SMF indicating "shared MBS traffic delivery will not be used", "separate delivery will be used", or "roaming UE".

[0084] The response may be piggybacked into a Next Generation Application Protocol (NGAP) message, which may also include a new indication, namely "Shared MBS traffic delivery should not be used", "Use separate delivery", or "Roaming UE from V-AMF to V-NG-RAN"; therefore, V-NG-RAN may not establish shared MBS traffic delivery for the multicast MBS session. Alternatively, if no indication is received, multicast separate delivery will be established by default. Alternatively, V-NG-RAN may have been notified in the UE context setup message that the UE is in a roaming state or has received the HPLMN identifier of the UE, so that V-NG-RAN knows that the UE is a roaming UE, and based on this, V-NG-RAN may not establish shared MBS traffic delivery for the multicast MBS session.

[0085] In various example embodiments, a Join_Accept message may be provided from the V-SMF to the UE (e.g., via a DL PDU Session Modification Command message). If the join request is sent in a PDU Session Establishment Request (as it may also be sent via a PDU Session Modification Request based on the 3GPP Rel-17 Join Process), the V-SMF and the H-SMF may exchange transport addresses to begin establishing an N9 tunnel between the V-UPF and the H-UPF, which may also be used for the delivery of multicast MBS session traffic. If the H-UPF has not yet received MBS multicast data, the H-SMF may request from the H-MB-SMF to establish a unicast transport tunnel, which is used for multicast MBS session delivery between the H-MB-UPF and the H-UPF. The H-SMF may then configure the H-UPF to send the MBS multicast data received from the H-MB-UPF as a unicast QoS flow within the PDU Session N9 tunnel to the V-UPF. The V-SMF may configure the V-UPF to forward the associated QoS flow as a home-routed PDU session flow. On the user plane side, and after the roaming UE has successfully joined the MBS session, the multicast MBS traffic thus travels via the AF, H-MB-UPF, PSA UPF (H-UPF), V-UPF, V-NG-RAN, and finally reaches the UE.

[0086] Certain example embodiments may involve a UE roaming in a VPLMN that is configured to leave a multicast MBS service provided by the HPLMN (i.e., an outbound roamer). For example, the UE may trigger a leave request (e.g., a PDU session modification process) to the V-SMF in the VPLMN to leave the multicast MBS session. An MBS-related request from a UE in the VPLMN (i.e., to leave a multicast MBS session) may require a new signal to be sent from the V-SMF to the H-SMF, and a response to be sent in the opposite direction. The V-SMF may then decide whether to forward the leave request to the H-SMF or handle the request itself based on the PDU session used by the UE. For example, for a locally routed PDU session, a multicast MBS service may be provided by the HPLMN, and the H-SMF may be contacted. However, for a locally routed PDU session, a multicast MBS service may be provided by the VPLMN. After the UE leaves the multicast MBS service, the H-SMF may request the V-SMF to remove the unicast QoS flow established for unicast delivery of the multicast MBS service. The V-SMF may then request the V-NG-RAN node (e.g., via the V-AMF) to remove the unicast QoS flow. The H-SMF may also configure the H-UPF to stop sending MBS multicast data received from the H-MB-UPF as a unicast QoS flow to the V-UPF within the PDU session N9 tunnel. The H-SMF may also request from the H-MB-SMF to remove the unicast MBS session transport tunnel between the H-MB-UPF and the PSA UPF (e.g., H-UPF) if there are no remaining UEs to be served by the PSA UPF for the MBS service.

[0087] In certain example embodiments, the UE has successfully joined a multicast MBS session in its HPLMN. The UE may transition from the HPLMN to a VPLMN (ie, inter-PLMN mobility). The HPLMN may then determine whether the UE is authorized to continue receiving the multicast MBS service.

[0088] During the HPLMN to VPLMN handover preparation, the V-SMF may send an Nsmf_PDUSession_Create request including the VPLMNID to the H-SMF (i.e., the serving network), resulting in V-SMF insertion. During the handover operation, the H-AMF may receive a Handover_required message from the H-NG-RAN, which may include an N2SM container handover requirement transfer information element (IE), which may in turn include multicast MBS session information of the (multiple) MBS sessions to which the UE has joined and the (multiple) associated PDU sessions. The handover requirement transfer IE may be transparently relayed by the H-AMF, forwarding the information to the V-AMF, which in turn may forward the information to the V-SMF. The V-SMF may then forward the information to the H-SMF. Based on its knowledge that the UE previously joined a multicast MBS session using this PDU session, the H-SMF can determine whether the roaming UE is authorized to continue receiving multicast MBS services provided by the HPLMN while the UE roams in this specific VPLMN (outbound roamer) or in general any V-PLMN. Information about multicast roaming authorization can be pre-configured in the HPLMN, configured by the AF, or obtained from the UDM (e.g., user subscription data).

[0089] Some example embodiments may include VPLMN being agnostic of the MBS session / multicast MBS stream associated with the PDU session. For example, if the H-SMF determines that the UE is not authorized to continue receiving the multicast MBS service in the VPLMN, the H-SMF may request the V-SMF to remove any unicast QoS streams associated with the multicast MBS service from the PDU session. Assume that these QoS streams are requested to be switched to the VPLMN. The V-SMF may then remove the unauthorized roaming UE from the multicast MBS service by not including the unicast QoS streams associated with the MBS in the switching request message to the V-NG-RAN. Additionally or alternatively, the H-SMF may request the V-SMF to indicate to the UE that the UE is removed from the MBS multicast session, indicating the reason for joining the MBS session from a VPLMN from which the UE is not authorized to roam or from any VPLMN. In this case, if the UE is in the same VPLMN or from any VPLMN based on the reason received, the UE may not request to join in the future.

[0090] The H-SMF may trigger a PDU Session Modification process to the V-SMF or as a response to a PDU Session Create Request. If separate delivery was previously used, the H-SMF may also configure the H-UPF to stop sending MBS multicast data received from the H-MB-UPF as a unicast QoS flow within the PDU Session N9 tunnel to the V-UPF.

[0091] In various example embodiments, if the H-SMF determines that the UE is authorized to continue to receive the multicast MBS service in the VPLMN, the H-SMF may request the V-SMF to establish a unicast QoS flow associated with the multicast MBS service for the PDU session (if shared delivery was used in the HPLMN before inter-PLMN mobility and no associated QoS flow was provided to the NG-RAN), and may map the QoS information of the multicast QoS flow to the unicast QoS flow information of the PDU session and include the information in the response to the V-SMF. To this end, the H-SMF may trigger a PDU session modification process to the V-SMF, or as a response to a PDU session creation request. If separate delivery was not used before, the H-SMF may also configure the H-UPF to send the MBS multicast data received from the H-MB-UPF to the V-UPF as a unicast QoS flow within the PDU session N9 tunnel. In the above example, the H-SMF may not provide multicast MBS related information to the V-SMF and V-NG-RAN (i.e., the VPLMN is not aware of the multicast MBS session).

[0092] Certain example embodiments may include the VPLMN being aware of the MBS session / multicast MBS flow associated with the PDU session. If the H-SMF determines that the UE is not authorized to continue receiving the multicast MBS service in the VPLMN, the H-SMF may request the V-SMF to trigger a process to remove the unauthorized roaming UE from the multicast MBS service. The H-SMF may request the V-SMF to remove the unicast QoS flows associated with the multicast MBS service (e.g., if unicast delivery was also used in the HPLMN before inter-PLMN mobility) from the PDU session (e.g., these QoS flows may have been requested to be switched to the VPLMN). The V-SMF may then remove the unauthorized roaming UE from joining the multicast MBS service by not including the unicast QoS flows associated with the MBS in the handover request message towards the V-NG-RAN. The V-SMF may trigger a DL PDU session modification process to the UE to indicate to the UE that it is removed from the multicast MBS session. The V-SMF may provide the UE with a reason that may have been sent from the H-SMF indicating that the UE is not authorized to join the MBS session from the VPLMN or any VPLMN. Based on the reason received, the UE may not request to join in the future if it is in the same VPLMN or from any VPLMN. The H-SMF may also configure the H-UPF to stop sending MBS multicast data received from the H-MB-UPF as a unicast QoS flow within the PDU Session N9 tunnel to the V-UPF if separate delivery was previously used.

[0093] In certain example embodiments, this may include the VPLMN being aware of the MBS session / multicast MBS flow associated with the PDU session. If the H-SMF determines that the UE is authorized to continue receiving multicast MBS services in the VPLMN, the H-SMF may request the V-SMF to establish a unicast QoS flow associated with the multicast MBS service for the PDU session (if shared delivery was used in the HPLMN before inter-PLMN mobility), and may map the QoS information of the multicast QoS flow to the unicast QoS flow information of the PDU session, and include the information in the response to the V-SMF. The H-SMF may respond to the V-SMF by indicating a new indication, which is "shared MBS traffic delivery will not be used", "separate delivery" or "roaming UE". Alternatively, if no indication is received, a default multicast separate delivery may be established.

[0094] The V-SMF provides the response back to the V-AMF, which forwards to the V-NG-RAN, where a new indication of "shared MBS traffic delivery should not be used", "separate delivery" or "roaming UE" is attached in the NG application protocol message. Since the response includes the new indication of "shared MBS traffic delivery should not be used", the V-NG-RAN does not establish shared MBS traffic delivery for the multicast MBS session. Alternatively, the V-AMF may send an indication to the V-NG-RAN that the UE is a roaming UE, or may send the HPLMN ID of the UE to the V-NG-RAN, and upon determining that the UE is a roaming UE, the V-NG-RAN decides not to trigger the establishment of shared MBS traffic delivery.

[0095] To establish separate MBS traffic delivery, the V-SMF and H-SMF may exchange transport addresses to establish a unicast tunnel between the PSA UPF (e.g., H-UPF) and the V-UPF (if not already established). If separate delivery was not used before, the H-SMF may also configure the H-UPF to send the MBS multicast data received from the H-MB-UPF to the V-UPF as a unicast QoS flow within the PDU Session N9 tunnel. On the user plane side, and after the roaming UE has successfully joined the MBS session, the multicast MBS traffic may be delivered via the AF, H-MB-UPF, PSA UPF (H-UPF), V-UPF, V-NG-RAN, and finally to the UE.

[0096] Certain example embodiments may include a UE moving from a VPLMN to a HPLMN. For example, upon mobility from a VPLMN to a HPLMN, if the UE may be allowed to join the MBS service in the source VPLMN, and if shared delivery may be used in the HPLMN, the H-SMF may remove the QoS flow for unicast delivery and switch to shared delivery during or after inter-PLMN mobility.

[0097] Various example embodiments may include a UE moving from a VPLMN 1 to a VPLMN 2. In this case, some of the techniques described above (e.g., HPLMN to VPLMN) may apply, but if the UE is authorized to join multicast MBS services in the source VPLMN 1, and is also authorized to do so in the target VPLMN 2, the H-SMF may not establish a new unicast QoS flow, as the existing QoS flows are expected to be handed over from VPLMN 1 to VPLMN 2 as regular / non-MBS QoS flows.

[0098] Figures 1A-1C An example of a signaling diagram 100 is illustrated, which depicts a UE joining process in a VPLMN for a multicast MBS service provided by an HPLMN. According to certain example embodiments, UE 130 may be similar to UE 1320, and V-NG-RAN 135, V-AMF 140, V-SMF 145, V-UPF 150, V-MB-SMF 155, H-SMF 160, H-MB-SMF 165, H-MB-UPF 170, and AF 175 may be similar to NE 1310, and as shown in FIG. Fig.13 shown.

[0099] At operation 101a, the UE 130 may send a UL NAS message (eg, N1 SM container (PDU Session Modification Request)) to the V-AMF 140.

[0100] In operation 101b, the V-AMF 140 may send a Nsmf_PDUsession_UpdateSMContext request to the V-SMF 145.

[0101] In operation 101c , the V-SMF 145 may send a Nsmf_PDUSession_Update request (PDU session ID, join request+multicast MBS session ID) to the H-SMF 160 , followed by a response returned to the V-SMF 145 .

[0102] In operation 102, the H-SMF 160 and the H-MB-SMF 165 may exchange Nmbsmf_MBSSession_ContextStatusSubscribe request and response messages.

[0103] At operation 103a, H-SMF 160 may determine whether UE 130 is authorized to join the multicast MBS session of the VPLMN, wherein H-SMF 160 may use local configuration, information provided by AF 175, and / or contact UDM to receive the authorization.

[0104] In operation 103b, if H-SMF 160 determines that UE 130 is not authorized, the PDU modification request may be rejected, and rejection information may be sent from H-SMF 160 to V-SMF 145, V-AMF 140, V-NG-RAN 135, and then to UE 130.

[0105] At operation 103c, after receiving the rejection information at operation 103b, the UE 130 may stop attempting to join the MBS session in the same VPLMN or any other VPLMN after receiving the rejection cause.

[0106] In operation 104 , if the authorization check of operation 103 a succeeds, the H-SMF 160 may determine to establish a new unicast QoS flow for the multicast QoS flow obtained from the H-MB-SMF 165 .

[0107] In operation 105a, the H-SMF 160 may send an Nsmf_PDUSession_Update request to the V-SMF 145, which may include a flag indicating that shared MBS delivery is not permitted and that a unicast QoS flow should be established.

[0108] At operation 105b, the V-SMF 145 may send a Namf_Communication_N1N2message delivery to the V-AMF 140, which may be an N2 SM PDU, which may include a flag (when received) indicating that shared MBS delivery is not permitted and that a unicast QoS flow should be established.

[0109] At operation 106, the V-AMF 140 may send an N2 message request to the V-NG-RAN 135, which may include a flag indicating that shared MBS delivery is not permitted and that a unicast QoS flow should be established.

[0110] In operation 107 , the V-NG-RAN 135 may not establish shared MBS traffic delivery.

[0111] At operation 108, UE 130 and V-NG-RAN 135 may exchange RRC messages including a PDU session modification command.

[0112] At operation 109 , the V-NG-RAN 135 may send an N2 message response to the V-AMF 140 .

[0113] In operation 110 , the V-AMF 140 may send a Nsmf_PDUsession_UpdateSMContext request to the V-SMF 145 , which may be forwarded to the H-SMF 160 .

[0114] In operation 111, the H-SMF 160, the H-MB-SMF 165, and the H-MB-SMF 170 may exchange Nbmsmf_MBSSession_ContextUpdate requests and responses configured to start MBS data delivery.

[0115] At operation 112, the H-SMF 160 and the H-UPF 180 may generate a configuration for forwarding the MBS multicast data within the PDU session.

[0116] In operation 113 , the AF 175 may transmit the multicast data to the H-MB-UPF 170 , and the H-MB-UPF may transmit the multicast data to the H-UPF 180 via the PDU session in operation 114 .

[0117] In operation 115, the H-UPF 180 may transmit the multicast data to the V-UPF 150 via the PDU session.

[0118] At operation 116 , the V-UPF 150 may transmit the multicast data to the V-NG-RAN 135 via the PDU session, and the V-NG-RAN may transmit the multicast data to the UE 130 via the PDU session at operation 117 .

[0119] Figures 2A-2C An example of a signaling diagram 200 is illustrated when a UE that has joined a multicast MBS session in the HPLMN moves from the HPLMN to the VPLMN, and the UE is authorized to continue receiving the multicast MBS session. According to certain example embodiments, the UE 230 may be similar to the UE 1320, and the home NG-RAN 235, the visited NG-RAN 240, the H-AMF 245, the V-AMF 250, the V-SMF 255, the V-UPF 260, the H-SMF 265, the H-UPF 270, the home MB-SMF 275, and the home MB-UPF 280 may be similar to the NE 1310, and as shown in FIG. Fig.13 shown.

[0120] At operation 201 , the home NG-RAN 235 may send a handover required message including MBS session information and / or related PDU session information to the H-AMF 245 .

[0121] In operation 202 , the H-AMF 245 may transmit a Namf_Communication_CreateUEContext request message including MBS session information and / or associated PDU session information to the V-AMF 250 .

[0122] In operation 203a, the V-AMF 250 may send a Nsmf_PDUsession_CreateSMContext request including a PDU session ID and / or N2 SM information to the V-SMF 255.

[0123] In operation 203b, the V-SMF 255 may send a NSmf_PDUSession_Create request including a PDU session ID and / or a multicast MBS session ID to the H-SMF 265.

[0124] At operation 203c, the H-SMF 265 may check whether the mobile UE 230 is authorized to continue to join the multicast MBS session in the VPLMN, wherein the H-SMF 265 may use the location configuration, information received from the AF, or request authorization from the UDM.

[0125] In operation 204 , if the authorization check passes, the H-SMF 265 may determine whether unicast QoS flow information corresponding to the QoS information of the multicast QoS flow is required, including the unicast QoS flow information in a response to the V-SMF 255 .

[0126] In operation 205a, the H-SMF 265 may send a Nsmf_PDUSession_Create response to the V-SMF 255, including a unicast QoS flow and an optional flag indicating that shared MBS delivery is not allowed.

[0127] At operation 205b, the V-SMF 255 may send a Nsmf_PDUsession_CreateSMContext response to the V-AMF 250, including the unicast QoS flow and, optionally, a flag indicating that shared MBS delivery is not allowed.

[0128] At operation 206, the V-AMF 250 may send a handover request to the visited NG-RAN 240, including the unicast QoS flow and, optionally, a flag indicating that shared MBS delivery is not allowed.

[0129] At operation 207, the visited NG-RAN 240 may be unable to establish shared MBS traffic delivery.

[0130] At operation 208 , the visited NG-RAN 240 may send a handover request confirmation to the V-AMF 250 .

[0131] In operation 209, the V-AMF 250 and the V-SMF 255 may exchange Nsmf_PDUsession_UpdateSMContext requests and responses.

[0132] At operation 210, the V-AMF 250 may send a Namf_Communiaction_Create UE context response to the H-AMF 245. At operation 211, the H-AMF 245 may send a handover command to the home NG-RAN 235, which may forward the RRC handover command or reconfiguration to the UE 230 at operation 212. At operation 213, the UE 230 may send a handover confirmation or a handover completion indication to the visited NG-RAN 240. At operation 214, the visited NG-RAN 240 may send a handover notification to the V-AMF 250. At operation 215, the V-AMF 250 may send a Nsmf_PDUsession_UpdateSMContext request to the V-SMF 255.

[0133] At operation 216, the H-SMF 265 may establish a traffic tunnel for separate MBS traffic delivery, where the V-SMF 255 and the H-SMF 265 may exchange transport addresses to establish a unicast tunnel between the PSA UPF (eg, H-UPF 270) and the V-UPF 260 if not already established.

[0134] In operation 217 , the V-SMF 255 may send a Nsmf_PDUsession_UpdateSMContext response to the V-AMF 250 .

[0135] At operation 218, the H-SMF 265 may generate a configuration for forwarding the MBS multicast data within the PDU session if separate delivery was not previously applied.

[0136] Figures 3A-3DAn example of a signaling diagram 300 is illustrated when a UE that has joined a multicast MBS session in the HPLMN moves from the HPLMN to the VPLMN and the UE is not authorized to continue receiving the multicast MBS session. According to certain example embodiments, the UE 330 may be similar to the UE 1320, and the home NG-RAN 335, the visited NG-RAN 340, the H-AMF 345, the V-AMF 350, the V-SMF 355, the V-UPF 360, the H-SMF 365, the H-UPF 370, the home MB-SMF 375, and the home MB-UPF 380 may be similar to the NE 1310, and as Fig.13 shown.

[0137] At operation 301 , the home NG-RAN 335 may send a handover required message including MBS session information and / or related PDU session information to the H-AMF 345 .

[0138] In operation 302 , the H-AMF 345 may send a Namf_Communication_CreateUEContext request including MBS session information and / or associated PDU session information to the V-AMF 350 .

[0139] In operation 303a, the V-AMF 350 may send a Namf_Communication_CreateSMContext request including the PDU session ID and / or N2 SM information to the V-SMF 355.

[0140] In operation 303b, the V-SMF 355 may send a NSmf_PDUSession_Create request including a PDU session ID and / or a multicast MBS session ID to the H-SMF 365.

[0141] At operation 304a, the H-SMF 365 may check whether the roaming UE 330 is authorized to continue to join the multicast MBS session in the VPLMN, wherein the H-SMF 365 may use the location configuration, information provided by the AF, or contact the UDM to receive the authorization.

[0142] At operation 304b, the H-SMF 365 may determine that the UE 330 is not authorized to receive / continue to receive multicast MBS traffic in the VPLMN, and determine to remove a unicast QoS flow for the multicast service, if any.

[0143] In operation 305a, the H-SMF 365 may send an Nsmf_PDUSession_Create response to the V-SMF 355 without an associated unicast MBS QoS flow.

[0144] In operation 305b, the V-SMF 355 may send a Nsmf_PDUsession_CreateSMContext response without an associated unicast MBS QoS flow to the V-AMF 350.

[0145] At operation 306 , the V-AMF 350 may send a handover request without an associated unicast MBS QoS flow to the visited NG-RAN 340 .

[0146] In operation 307, the related MBS-related QoS flow may not be established.

[0147] At operation 308 , the visited NG-RAN 340 may send a handover request confirmation to the V-AMF 350 .

[0148] In operation 309, the V-AMF 350 and the V-SMF 355 may exchange Nsmf_PDUsession_UpdateSMContext requests and responses.

[0149] In operation 310 , the V-AMF 350 may send a Namf_Communication_CreateUEContext response to the H-AMF 345 .

[0150] At operation 311 , the H-AMF 345 may send a handover command to the home NG-RAN 335 , and at operation 312 , the home NG-RAN 335 may forward the RRC handover reconfiguration received in the handover command to the UE 330 .

[0151] At operation 313, the UE 330 may send a handover confirmation or a handover completion indication to the visited NG-RAN 340. At operation 314, the visited NG-RAN 340 may send a handover notification to the V-AMF 350. At operation 315, the V-AMF 350 may send a Nsmf_PDUsession_UpdateSMContext request to the V-SMF 355.

[0152] At operation 316, the traffic tunnel between the V-UPF 360 and the H-UPF 370 may be removed if no longer needed.

[0153] At operation 317, the H-SMF 365 may send a Nsmf_PDUSession_Update request to the V-SMF 355, the request being configured to remove the UE 330 from the multicast MBS session with a new cause.

[0154] At operation 318, the V-SMF 355 may send a trigger for a PDU session modification request procedure to the UE 330 to remove the UE 330 from the multicast MBS session with a new cause, and receive a response.

[0155] At operation 318a, after receiving the new rejection cause, the UE 330 may not retry joining the same VPLMN or any other VPLMN.

[0156] In operation 319 , the V-SMF 365 may send an Nsmf_PDUSession_Update response to the H-SMF 365 .

[0157] In operation 320, if separate delivery was previously applied, the H-SMF 365 and / or the H-UPF 370 may generate a configuration to stop forwarding MBS multicast data within the PDU session.

[0158] In operation 321 , the V-SMF 355 may send a Nsmf_PDUsession_UpdateSMContext response to the V-AMF 350 .

[0159] Figure 4 The diagram illustrates a method that can be performed by a NE (such as Fig.13 An example of a flowchart of method 400 performed by NE 1310) shown in FIG.

[0160] In step 401, the method may include receiving, by a home session management function (H-SMF) from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in the VPLMN to join a multicast multicast and broadcast service (MBS) session.

[0161] In step 402, the method may further include determining, by the H-SMF, whether the UE is authorized to join the multicast MBS session. The determination may be based on at least one of the following: local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager.

[0162] In step 403, the method may further include: based on determining that the UE is authorized to join the multicast MBS session, the H-SMF sends an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, the H-SMF sends a rejection response including error cause information to the V-SMF, the error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming. The acceptance response may indicate that the at least one unicast QoS flow has no relationship with the multicast MBS session.

[0163] In certain example embodiments, the error cause information may indicate that the UE is not authorized to join the multicast MBS session while roaming in the VPLMN.In addition, the join request may be included in the update request.

[0164] In some example embodiments, the acceptance response may indicate the relationship of at least one unicast QoS flow to the multicast MBS session, and at least one unicast QoS flow information, or at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of a roaming user device.

[0165] In step 404, the method may further include receiving, by the H-SMF from the V-SMF, a leave request requesting the UE to leave the multicast MBS session managed in the PLMN of the H-SMF, and sending, by the H-SMF to the V-SMF, a request to remove at least one unicast QoS flow corresponding to at least one multicast QoS flow associated with the multicast session. The UE may be authorized to join the multicast MBS session.

[0166] In step 405, the method may also include determining, by the H-SMF, that the UE is removed from the multicast MBS session, and sending, by the H-SMF, a request to the V-SMF, the request including at least one of: a request to remove a unicast QoS flow associated with the multicast MBS session, a request to indicate to the UE that the UE is removed from the MBS multicast session, or a request to remove the UE from the multicast MBS session.

[0167] In various example embodiments, a request to remove the UE from an MBS multicast session is indicated to the UE, or a request to remove the UE from a multicast MBS session indicates that the UE is not authorized to join the MBS session from a VPLMN it roamed into, or from any VPLMN it roamed.

[0168] Figure 5 The diagram illustrates a method that can be performed by a NE (such as Fig.13 An example of a flowchart of method 500 performed by NE 1310) shown in FIG.

[0169] At step 501, the method may include: receiving, by a visited session management function (V-SMF), from a UE a join request requesting the UE to join a multicast MBS session.

[0170] In certain example embodiments, the receiving may also include: receiving, by the V-SMF, a response accepting the join request and configured to establish at least one unicast QoS flow, wherein the response indicates at least one of the following for the at least one unicast QoS flow: shared MBS traffic delivery should not be used, separate delivery should be used, or the UE is roaming; and sending, by the V-SMF, session management signaling configured to establish at least one unicast QoS flow, wherein the session management signaling indicates at least one of the following for the at least one unicast QoS flow: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication that the UE is roaming.

[0171] At step 502, the method may include determining, by the V-SMF, that a PDU session associated with the join request is towards a home routing PDU session of the H-SMF.

[0172] At step 503, the method may include: sending a join request to the identified H-SMF according to the determination.

[0173] At step 504, the method may further include: receiving, by the V-SMF, at least one of an acceptance response or a rejection response to the join request, the acceptance response including a request to establish at least one unicast QoS flow.

[0174] In step 505, the method may further include: sending, by the V-SMF, a response to the join request to the UE.

[0175] In step 506, the method may also include: determining, by the H-SMF, that the UE will be removed from the multicast MBS session; and sending, by the H-SMF, a request to the V-SMF, the request including at least one of the following: a request to remove a unicast QoS flow associated with the multicast MBS session, a request to indicate to the UE that the UE is removed from the MBS multicast session, or a request to remove the UE from the multicast MBS session.

[0176] In some example embodiments, the request to remove the UE from the MBS multicast session is indicated to the UE or the request to remove the UE from the multicast MBS session indicates that the UE is not authorized to join the MBS session from the VPLMN it roamed into or from any VPLMN it roamed.

[0177] Figure 6 The diagram illustrates a method that can be performed by a NE (such as Fig.13An example of a flowchart of method 600 performed by NE 1310) shown in FIG.

[0178] In step 601, the method may include: receiving signaling by the NG RAN node to establish at least one unicast QoS flow to the UE, wherein the signaling indicates for the at least one unicast QoS flow that it is related to an MBS multicast session and indicates at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of the UE.

[0179] At step 602, the method may further include configuring at least one radio bearer to send at least one unicast QoS flow to the UE.

[0180] At step 603, the method may further include: storing the received indication for the at least one unicast QoS flow in the multicast MBS session context.

[0181] Figure 7 The diagram illustrates a method that can be performed by a NE (such as Fig.13 An example of a flowchart of method 700 performed by NE 1310) shown.

[0182] At step 701, the method may include: receiving, by a Home Session Management Function (H-SMF), a join request requesting a UE to join a multicast MBS session.

[0183] In step 702, the method may further include: receiving, by the H-SMF, an N2SM container switching requirement transfer information element from the V-SMF in the first VPLMN, the N2SM container switching requirement transfer information element including multicast MBS session information of at least one MBS session to which the UE has joined.

[0184] At step 703, the method may further include: when the UE is roaming in the first VPLMN, determining, by the H-SMF, whether the UE is authorized to continue to receive the multicast MBS session. In some example embodiments, the determination may be based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager. In various example embodiments, the determination may be performed if the UE was previously located in the home PLMN or the second VPLMN and is handed over to the first VPLMN.

[0185] At step 704, the method may further include: when it is determined that the UE is not authorized to continue to receive the multicast MBS service in the VPLMN, sending a request by the H-SMF to the V-SMF to indicate to the UE that the UE is removed from the MBS multicast session. In certain example embodiments, the request to indicate to the UE that the UE is removed from the MBS multicast session may include a reason indicating that the UE is not authorized to join the MBS session from the VPLMN into which it is roaming or from any VPLMN roaming.

[0186] In step 705, the method may further include: if shared delivery was used in the HPLMN before inter-PLMN mobility when it is determined that the UE is authorized to continue to receive the multicast MBS service in the VPLMN, a request is sent by the H-SMF to the V-SMF to establish at least one unicast QoS flow corresponding to the multicast QoS flow information received from the H-MB-SMF. The request configured to establish at least one unicast QoS flow corresponding to the multicast QoS flow information received from the H-MB-SMF may not indicate the relationship of the unicast QoS flow to the multicast MBS session. The request configured to establish at least one unicast QoS flow corresponding to the multicast QoS flow information received from the H-MB-SMF may indicate at least one of the following: the relationship of the unicast QoS flow to the multicast MBS session, an indication that shared delivery should not be used, an indication that separate delivery should be used, or an indication of a roaming UE.

[0187] Figure 8 The diagram illustrates a method that can be performed by a NE (such as Fig.13 An example of a flowchart of method 800 performed by NE 1310) shown.

[0188] In step 801, the method may include: receiving, by a visited session management function (V-SMF) from an AMF, a handover requirement transfer information element for a home routing PDU session anchored at an H-SMF.

[0189] At step 802, the method may further include: sending a handover requirement delivery information element to the identified H-SMF.

[0190] In step 803, the method may also include: in response to sending a switching requirement delivery information element to the H-SMF, the V-SMF receives a reply message, the reply message including at least one of the following: a request to indicate to the UE that the UE is removed from the MBS multicast session, or a configuration to establish at least one unicast QoS flow.

[0191] In step 804, the method may further include: receiving, by the V-SMF, a request from the H-SMF to indicate to the UE that the UE is removed from the MBS multicast session, and sending, by the V-SMF, to the UE an indication that the UE is removed from the MBS multicast session. The indication sent to the UE that it is removed from the multicast MBS session may include at least one associated reason if it is included in the request received from the H-SMF.

[0192] In step 805, the method may also include: the V-SMF receives a reply message from the H-SMF, the reply message includes a configuration for establishing at least one unicast QoS flow, and the V-SMF sends a session management signaling, the session management signaling is configured to establish at least one unicast QoS flow.

[0193] In step 806, the method may further include: receiving, by the V-SMF, a reply message from the H-SMF, the reply message including: a configuration for establishing at least one unicast QoS flow, and an indication for at least one unicast QoS flow, the indication indicating at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication that the UE is roaming, and sent by a V-SMF session management signaling configured to establish the at least one unicast QoS flow, wherein the session management signaling indicates at least one of the following for the at least one unicast QoS flow: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication that the UE is roaming. The reply message from the H-SMF may indicate for at least one unicast QoS flow that it is associated with an MBS session, and the method may further include storing, by the V-SMF, the at least one unicast QoS flow that it is associated with the MBS session.

[0194] Fig. 9 FIG. 1 illustrates a method that may be performed by a UE (such as a Fig.13 An example of a flowchart of method 900 performed by UE 1320) shown in FIG.

[0195] At step 901 , the method may include: a user equipment roaming in a VPLMN sends a request to join a multicast MBS session.

[0196] At step 902, the method may further include: receiving, by the UE, a join request rejection message indicating that the UE is not allowed to access the MBS session when roaming.

[0197] At step 903, the method may further include: when roaming, refraining from sending an additional join request for the MBS session.

[0198] Fig.10 FIG. 1 illustrates a method that may be performed by a UE (such as a Fig.13 An example of a flowchart of method 1000 performed by UE 1320) shown in FIG.

[0199] At step 1001 , the method may include: a user equipment roaming in a VPLMN sends a request to join a multicast MBS session.

[0200] At step 1002, the method may further include: receiving, by the UE, a join request rejection message indicating that the UE is not allowed to access the MBS session when roaming in the VPLMN.

[0201] At step 1003, the method may further include: when roaming in a VPLMN, suppressing sending an additional join request for the MBS session.

[0202] Fig.11 The diagram illustrates a method that can be performed by a NE (such as Fig.13 An example of a flowchart of method 1100 performed by NE 1310) shown.

[0203] At step 1101 , the method may include: a user equipment sending a request to join a multicast MBS session.

[0204] At step 1102, the method may further include: roaming in the VPLMN.

[0205] At step 1103 , the method may further include: receiving, by the UE, an indication that the UE is removed from the MBS session, the indication having a reason that the UE is not allowed to access the MBS multicast session when roaming.

[0206] At step 1104, the method may further include: when roaming, refraining from sending additional join requests for the MBS multicast session.

[0207] Fig.12 FIG. 1 illustrates a method that may be performed by a UE (such as a Fig.13 An example of a flowchart of a method 1200 performed by a UE 1320) shown in FIG.

[0208] At step 1201 , the method may include: a user equipment sending a request to join a multicast MBS.

[0209] At step 1202, the method may further include: roaming in the VPLMN.

[0210] At step 1203, the method may further include: receiving, by the UE, an indication that the UE is removed from the MBS session, the indication having a reason that the UE is not allowed to access the MBS multicast session when roaming in the VPLMN.

[0211] At step 1204, the method may further include: when roaming in the VPLMN, refraining from sending additional join requests for the MBS multicast session.

[0212] Fig.13 An example of a system according to some example embodiments is illustrated. In an example embodiment, the system may include a plurality of devices, such as NE 1310 and / or UE 1320 .

[0213] NE 1310 may be one or more of the following: a base station (e.g., a 3G UMTS NodeB, a 4G LTE evolved NodeB, or a 5G NR next-generation NodeB), a serving gateway, a server, and / or any other access node or a combination thereof.

[0214] The NE 1310 may also include at least one gNB centralized unit (CU), which may be associated with at least one gNB distributed unit (DU). The at least one gNB-CU and the at least one gNB-DU may communicate via at least one F1 interface, at least one Xn-C interface, and / or at least one NG interface via a fifth generation core (5GC).

[0215] UE 1320 may include one or more mobile devices, such as mobile phones, smart phones, personal digital assistants (PDAs), tablet computers or portable media players, digital cameras, compact cameras, video game consoles, navigation units, such as global positioning system (GPS) devices, desktop or laptop computers, single-location devices, such as sensors or smart meters, or any combination thereof. In addition, NE 1310 and / or UE 1320 may be one or more Citizen Broadband Radio Service Devices (CBSDs).

[0216] NE 1310 and / or UE 1320 may include at least one processor, respectively represented as 1311 and 1321. Processors 1311 and 1321 may be embodied by any computing or data processing device, such as a central processing unit (CPU), an application specific integrated circuit (ASIC), or the like. The processor may be implemented as a single controller, or multiple controllers or processors.

[0217] At least one memory may be provided in one or more devices, as shown at 1312 and 1322. The memory may be fixed or removable. The memory may include computer program instructions or computer codes contained therein. Memories 1312 and 1322 may independently be any suitable storage device, such as a non-transitory computer-readable medium. The term "non-transitory" used herein may correspond to the limitations of the medium itself (i.e., tangible, not a signal), rather than limitations on data storage persistence (e.g., random access memory (RAM) versus read-only memory (ROM)). A hard disk drive (HDD), random access memory (RAM), flash memory, or other suitable memory may be used. The memory may be combined on a single integrated circuit as a processor, or may be separated from one or more processors. In addition, the computer program instructions stored in the memory and that may be processed by the processor may be computer program codes in any suitable form, for example, a compiled or interpreted computer program written in any suitable programming language.

[0218] Processors 1311 and 1321, memories 1312 and 1322, and any subset thereof may be configured to provide Figure 1A-3D Although not shown, the device may also include positioning hardware, such as GPS or micro-electromechanical system (MEMS) hardware, which can be used to determine the location of the device. Other sensors are also permitted and can be configured to determine location, altitude, speed, direction, etc., such as a barometer, compass, etc.

[0219] like Fig.13 As shown, transceivers 1313 and 1323 may be provided, and one or more devices may also include at least one antenna, shown as 1314 and 1324, respectively. The device may have many antennas, such as an antenna array configured for multiple-input multiple-output (MIMO) communication, or multiple antennas for multiple RATs. For example, other configurations of these devices may be provided. Transceivers 1313 and 1323 may be transmitters, receivers, transmitters and receivers, or units or devices that may be configured for transmission and reception.

[0220] The memory and computer program instructions may be configured with a processor for a specific device to cause a hardware device, such as a UE, to perform any of the above processes (ie, Figure 1A-3D ). Thus, in some example embodiments, a non-transitory computer readable medium may be encoded with computer instructions that, when executed in hardware, perform a process such as one of the processes described herein. Alternatively, some example embodiments may be performed entirely in hardware.

[0221] In certain example embodiments, an apparatus may include a Figure 1A-3DCircuitry for any process or function shown. As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) a pure hardware circuit implementation (such as an implementation in analog and / or digital circuitry only), (b) a combination of hardware circuitry and software, such as (if applicable): (i) a combination of (multiple) analog and / or digital hardware circuits and software / firmware, and (ii) any portion of (multiple) hardware processors (including digital signal processors) with software, software, and (multiple) memories, which work together to enable a device (such as a mobile phone or server) to perform various functions, and (c) (multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or portions of (multiple) microprocessors, which require software (e.g., firmware) to operate, but the software may not be present when it is not required to operate. The definition of circuitry applies to all uses of the term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" also covers implementations of only hardware circuits or processors (or multiple processors) or portions of hardware circuits or processors and their (or their) accompanying software and / or firmware. For example, the term "circuitry" would also cover, if applicable to a particular claim element, a baseband integrated circuit or a processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or networking device.

[0222] Fig.14 An example of a 5G network and system architecture according to certain example embodiments is illustrated. A plurality of network functions are illustrated, which may be implemented as software operating as a component of a network device or dedicated hardware, as a network device itself or dedicated hardware, or as a virtual function operating as a network device or dedicated hardware. Fig.14 The NE and UE shown in the figure may be similar to NE 1310 and UE 1320, respectively. The user plane function (UPF) may provide services such as intra-RAT and inter-RAT mobility, routing and forwarding of data packets, packet inspection, user plane quality of service (QoS) processing, buffering of downlink packets and / or triggering of downlink data notifications. The application function (AF) may mainly interface with the core network to facilitate application usage of traffic routing and interact with the policy framework.

[0223] According to some example embodiments, processors 1311 and 1321 and memories 1312 and 1322 may be included in a processing circuit system or a control circuit system, or may form a part of a processing circuit system or a controller circuit system. In addition, in some example embodiments, transceivers 1313 and 1323 may be included in a transceiver circuit system, or may form a part of a transceiver circuit system.

[0224] In some example embodiments, an apparatus (e.g., NE 1310 and / or UE 1320) may include components for performing methods, processes, or any variations discussed herein. Examples of these components may include one or more processors, memories, controllers, transmitters, receivers, and / or computer program codes for performing operations.

[0225] In various example embodiments, the apparatus 1310 may be controlled by the memory 1312 and the processor 1311 to receive, from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in the VPLMN to join a multicast multicast and broadcast service (MBS) session, determine whether the UE is authorized to join the multicast MBS session, and based on determining that the UE is authorized to join the multicast MBS session, send an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, send a rejection response to the V-SMF, the rejection response including error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming. The determination is based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of a multicast MBS session, or user subscription data received from a user data manager.

[0226] Certain example embodiments may be directed to an apparatus including means for performing any of the methods described herein, including, for example, means for receiving, from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in a VPLMN to join a multicast multicast and broadcast service (MBS) session, and means for determining whether the UE is authorized to join the multicast MBS session. The determination is based on at least one of: a local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager. The method may also include a component for performing at least one of the following: based on determining that the UE is authorized to join the multicast MBS session, sending an acceptance response to the V-SMF, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from the home multicast / broadcast session management function (H-MB-SMF), or based on determining that the UE is not authorized to join the multicast MBS session, sending a rejection response to the V-SMF, the rejection response including: error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming.

[0227] In various example embodiments, the device 1310 can be controlled by the memory 1312 and the processor 1311 to receive a join request from the UE requesting the UE to join a multicast MBS session, determine that the protocol data unit (PDU) session associated with the join request is a home routed PDU session toward a home session management function (H-SMF), based on the determination, send the join request to the identified H-SMF, receive at least one of an acceptance response or a rejection response to the join request, the acceptance response including a request to establish at least one unicast QoS flow, and send a response to the join request to the UE.

[0228] Certain example embodiments may be directed to an apparatus comprising components for performing any of the methods described herein, including, for example, components for receiving a join request from a UE requesting the UE to join a multicast MBS session, components for determining that a protocol data unit (PDU) session associated with the join request is a home routed PDU session toward a home session management function (H-SMF), components for sending the join request to the identified H-SMF based on the determination; components for receiving at least one of an acceptance response or a rejection response to the join request, the acceptance response including a request to establish at least one unicast QoS flow; and components for sending a response to the join request to the UE.

[0229] In various example embodiments, the device 1310 can be controlled by the memory 1312 and the processor 1311 to receive signaling to establish at least one unicast QoS flow to the UE, wherein the signaling indicates for the at least one unicast QoS flow that it is related to the MBS multicast session and indicates at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication from the UE, configure at least one radio bearer to send at least one unicast QoS flow to the UE, and store the received indication for the at least one unicast QoS flow in the multicast MBS session context.

[0230] Certain example embodiments may be directed to an apparatus comprising components for performing any of the methods described herein, including, for example, components for receiving signaling to establish at least one unicast QoS flow to a UE, wherein the signaling indicates for the at least one unicast QoS flow that it is related to an MBS multicast session and indicates at least one of: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication of the UE; components for configuring at least one radio bearer to send the at least one unicast QoS flow to the UE; and components for storing the received indication for the at least one unicast QoS flow in a multicast MBS session context.

[0231] In various example embodiments, the apparatus 1310 may be controlled by the memory 1312 and the processor 1311 to receive a join request requesting the UE to join a multicast MBS session, receive an N2SM container switching requirement transfer information element from a V-SMF in a first VPLMN, the N2SM container switching requirement transfer information element including multicast MBS session information of at least one MBS session that the UE has joined, and determine whether the UE is authorized to continue to receive the multicast MBS session when the UE roams in the first VPLMN. The determination is based on at least one of the following: local configuration in the home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager.

[0232] Certain example embodiments may be directed to an apparatus including means for performing any of the methods described herein, including, for example, means for receiving a join request requesting a UE to join a multicast MBS session, means for receiving an N2SM container handover requirement transfer information element from a V-SMF in a first VPLMN, the N2SM container handover requirement transfer information element including multicast MBS session information of at least one MBS session that the UE has joined, and means for determining whether the UE is authorized to continue receiving the multicast MBS session while roaming in the first VPLMN. The determination is based on at least one of: a local configuration in a home public land mobile network, information received from an application function during establishment of the multicast MBS session, or user subscription data received from a user data manager.

[0233] In various example embodiments, the device 1310 can be controlled by the memory 1312 and the processor 1311 to receive a switching requirement delivery information element for a home routing PDU session anchored at the H-SMF from the AMF, send the switching requirement delivery information element to the identified H-SMF, and in response to sending the switching requirement delivery information element to the H-SMF, receive a reply message including at least one of the following: a request to indicate to the UE that the UE is removed from the MBS multicast session, or a configuration to establish at least one unicast QoS flow.

[0234] Certain example embodiments may be directed to an apparatus comprising components for performing any of the methods described herein, including, for example, components for receiving a handover requirement delivery information element for a home routing PDU session anchored at an H-SMF from an AMF, components for sending the handover requirement delivery information element to an identified H-SMF, and components for receiving a reply message in response to sending the handover requirement delivery information element to the H-SMF, comprising at least one of: indicating to the UE a request for the UE to be removed from the MBS multicast session, or establishing a configuration for at least one unicast QoS flow.

[0235] In various example embodiments, the device 1320 can be controlled by the memory 1322 and the processor 1321 to send a request to join a multicast MBS session, receive a join request rejection message indicating that the device is not allowed to access the MBS session when roaming, and refrain from sending additional join requests for the MBS session when roaming.

[0236] Certain example embodiments may be directed to an apparatus comprising means for performing any of the methods described herein, including, for example, means for sending a request to join a multicast MBS session, means for receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session while roaming, and means for refraining from sending additional join requests for the MBS session while roaming.

[0237] In various example embodiments, device 1320 may be controlled by memory 1322 and processor 1321 to send a request to join a multicast MBS session, receive a join request rejection message indicating that the device is not allowed to access the MBS session when the device is roaming in a VPLMN, and refrain from sending additional join requests for the MBS session when the device is roaming in a VPLMN.

[0238] Certain example embodiments may be directed to an apparatus comprising means for performing any of the methods described herein, including, for example, means for sending a request to join a multicast MBS session, means for receiving a join request rejection message indicating that the apparatus is not allowed to access the MBS session while roaming in a VPLMN, and means for refraining from sending additional join requests for the MBS session while roaming in the VPLMN.

[0239] In various example embodiments, the device 1320 can be controlled by the memory 1322 and the processor 1321 to send a request to join a multicast MBS session, roam in a VPLMN, receive an indication that the device is removed from the MBS session, the indication has a reason why the device is not allowed to access the MBS multicast session when roaming in the VPLMN, and refrain from sending additional join requests for the MBS multicast session when roaming in the VPLMN.

[0240] Certain example embodiments may be directed to an apparatus including means for performing any of the methods described herein, including, for example, means for sending a request to join a multicast MBS session, means for roaming in a VPLMN. The apparatus may also include: means for receiving an indication that the apparatus is removed from the MBS session, the indication having a reason that the apparatus is not allowed to access the MBS multicast session when roaming in the VPLMN; and means for refraining from sending additional join requests for the MBS multicast session when roaming in the VPLMN.

[0241] In various example embodiments, the device 1320 can be controlled by the memory 1322 and the processor 1321 to send a request to join a multicast MBS session, roam in a VPLMN, receive an indication that the device is removed from the MBS session, the indication having a reason why the device is not allowed to access the MBS multicast session while roaming in the VPLMN, and when roaming, refrain from sending additional join requests for the MBS multicast session.

[0242] Certain example embodiments may be directed to an apparatus including means for performing any of the methods described herein, including, for example, means for sending a request to join a multicast MBS session, means for roaming in a VPLMN. The apparatus may also include means for receiving an indication that the apparatus is removed from the MBS session, the indication having a reason that the apparatus is not allowed to access the MBS multicast session while roaming in the VPLMN, and means for refraining from sending additional join requests for the MBS multicast session while roaming.

[0243] The features, structures, or characteristics of the example embodiments described in this specification may be combined in any suitable manner in one or more example embodiments. For example, the use of the phrases "various embodiments," "certain embodiments," "some embodiments," or other similar language throughout this specification refers to the fact that a particular feature, structure, or characteristic described in conjunction with the example embodiments may be included in at least one example embodiment. Thus, the appearance of the phrases "in various embodiments," "in certain embodiments," "in some embodiments," or other similar language throughout this specification does not necessarily all refer to the same set of example embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments.

[0244] As used herein, “at least one of: ” and “at least one of ” and similar expressions, where a list of two or more elements is connected by “and” or “or”, mean at least any one element, or at least any two or more elements, or at least all elements.

[0245] In addition, if necessary, the above-mentioned different functions or processes can be performed in different orders and / or simultaneously with each other. In addition, if necessary, one or more described functions or processes can be optional or can be combined. Therefore, the above description should be considered as an explanation of the principles and teachings of some example embodiments, rather than a limitation thereof.

[0246] Those skilled in the art will readily appreciate that the above exemplary embodiments may be practiced by processes in a different order and / or hardware elements that are different from the disclosed configurations. Therefore, although some embodiments have been described based on these exemplary embodiments, certain modifications, variations, and alternative configurations will be apparent to those skilled in the art while remaining within the spirit and scope of the exemplary embodiments.

[0247] Partial Glossary

[0248] 3GPP Third Generation Partnership Project

[0249] 5G fifth generation

[0250] 5GC fifth generation core

[0251] 6G Sixth Generation

[0252] ACK

[0253] AF application function

[0254] AMF Access and Mobility Management Function

[0255] ASIC Application-Specific Integrated Circuit

[0256] CBSD Citizens Broadband Radio Service Equipment

[0257] CPU Central Processing Unit

[0258] CRC Cyclic Redundancy Check

[0259] CU Centralized Unit

[0260] DL Downlink

[0261] DU Distributed Unit

[0262] eMBB Enhanced Mobile Broadband

[0263] eNB Evolved Node B

[0264] gNBNext Generation Node B

[0265] GPS Global Positioning System

[0266] HDD Hard Drive

[0267] H-MB-SMF Home Multicast / Broadcast Session Management Function

[0268] HPLMN Home Public Land Mobile Network

[0269] H-UPF Home User Plane Function

[0270] IE Information Element

[0271] IoT

[0272] LTE Long Term Evolution

[0273] LTE-A Long Term Evolution Advanced

[0274] MBS Multicast and Broadcast System

[0275] MEMS Micro-Electro-Mechanical Systems

[0276] MIMO Multiple Input Multiple Output

[0277] mMTC massive machine type communication

[0278] NE Network Entity

[0279] NG Next Generation

[0280] NGAP Next Generation Application Protocol

[0281] NG-eNB Next Generation Evolved Node B

[0282] NG-RAN Next Generation Radio Access Network

[0283] NR New Radio

[0284] PDA Personal Digital Assistant

[0285] PDU Protocol Data Unit

[0286] QoS Quality of Service

[0287] RAM Random Access Memory

[0288] RAN Radio Access Network

[0289] RAT Radio Access Technology

[0290] RF Radio Frequency

[0291] ROM Read Only Memory

[0292] SMF session management functions

[0293] UDM Unified Data Manager

[0294] UE User Equipment

[0295] UMTS Universal Mobile Telecommunications System

[0296] UPF User Plane Function

[0297] URLLC Ultra-Reliable and Low-Latency Communications

[0298] UTRAN Universal Mobile Telecommunications System Terrestrial Radio Access Network

[0299] WLAN Wireless Local Area Network

Claims

1. A communication method, the method comprising: receiving, by a home session management function (H-SMF) from a visited session management function (V-SMF) in a visited public land mobile network (VPLMN), a join request originating from a user equipment (UE) roaming in the VPLMN to join a multicast multicast and broadcast service (MBS) session; as well as determining, by the H-SMF, whether the UE is authorized to join the multicast MBS session, wherein the determination is based on at least one of the following: Local configuration in a home public land mobile network, information received from an application function during establishment of said multicast MBS session, or User subscription data received from the User Data Manager, and Do at least one of the following: sending, by the H-SMF to the V-SMF, an acceptance response based on determining that the UE is authorized to join the multicast MBS session, the acceptance response being configured to establish at least one unicast quality of service (QoS) flow corresponding to the multicast QoS flow information received from a home multicast / broadcast session management function (H-MB-SMF), or Based on determining that the UE is not authorized to join the multicast MBS session, the H-SMF sends a rejection response to the V-SMF, where the rejection response includes error cause information indicating that the UE is not authorized to join the multicast MBS session when roaming.

2. The method according to claim 1, wherein the error cause information indicates that the UE is not authorized to join the multicast MBS session when roaming in the VPLMN.

3. The method according to any one of claims 1 to 2, wherein the join request is included in an update request.

4. The method according to any one of claims 1 to 3, wherein the acceptance response indicates that the at least one unicast QoS flow has no relation to the multicast MBS session.

5. The method according to any one of claims 1 to 2, wherein the acceptance response indicates: a relationship of the at least one unicast QoS flow to the multicast MBS session, and at least one of the following: Unicast QoS flow information, or at least one of the following: Indication that shared MBS traffic delivery should not be used, Separate delivery instructions should be used, or Indication of roaming user equipment.

6. The method according to any one of claims 1 to 5, wherein the UE is authorized to join the multicast MBS session, the method further comprising: receiving, by the H-SMF from the V-SMF, a leave request requesting the UE to leave the multicast MBS session managed in the PLMN of the H-SMF; as well as A request is sent by the H-SMF to the V-SMF to remove at least one unicast QoS flow corresponding to at least one multicast QoS flow associated with the multicast session.

7. The method according to any one of claims 1 to 6, further comprising: Determining, by the H-SMF, that the UE is to be removed from the multicast MBS session; as well as The H-SMF sends a request including at least one of the following to the V-SMF: a request to remove a unicast QoS flow associated with the multicast MBS session, indicating to the UE a request for the UE to be removed from the MBS multicast session, or A request to remove the UE from the multicast MBS session.

8. The method of claim 7, wherein the request to indicate to the UE that the UE is removed from the MBS multicast session, or the request to remove the UE from the multicast MBS session indicates that the UE is not authorized to join the MBS session from the VPLMN into which the UE is roaming, or from any VPLMN that the UE is roaming.

9. A communication method, the method comprising: receiving, by a visited session management function (V-SMF), from a UE a join request requesting the UE to join a multicast MBS session; Determining, by the V-SMF, that the PDU session associated with the join request is directed toward a home routing PDU session of the H-SMF; Based on the determination, sending the join request to the identified H-SMF; At least one of the following is received by the V-SMF: an acceptance response to the join request, including a request to establish at least one unicast QoS flow, or refuse to respond; as well as The V-SMF sends at least one of the acceptance response or the rejection response to the joining request towards the UE.

10. The method of claim 9, wherein receiving further comprises: Receiving, by the V-SMF, a response accepting the join request and configured to establish at least one unicast QoS flow, wherein the response indicates, for the at least one unicast QoS flow, at least one of the following: shared MBS traffic delivery should not be used, separate delivery should be used, or the UE is roaming; as well as The V-SMF sends session management signaling configured to establish at least one unicast QoS flow, wherein the session management signaling indicates at least one of the following for the at least one unicast QoS flow: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication that the UE is roaming.

11. The method according to any one of claims 9 to 10, wherein the response indicates, for the at least one unicast QoS flow, that the at least one unicast flow is related to the MBS session, and further comprising: Information indicating the at least one unicast QoS flow associated with the MBS session is stored by the V-SMF.

12. The method according to any one of claims 9 to 11, further comprising: receiving, by the V-SMF, from the UE a leave request requesting the UE to leave the multicast MBS session; as well as The leave request is sent by the V-SMF to the H-SMF.

13. The method according to any one of claims 9 to 12, further comprising: receiving, by the V-SMF from the H-SMF, a request to the UE indicating that the UE is removed from the MBS multicast session; as well as The V-SMF sends an indication to the UE that the UE is removed from the MBS multicast session.

14. The method according to claim 13, further comprising: At least one associated cause received in the request from the H-SMF is sent by the V-SMF to the UE.

15. The method according to any one of claims 9 to 14, further comprising: receiving, by the V-SMF from the H-SMF, a request to trigger removal of the UE from the multicast MBS session; determining a unicast QoS flow associated with the multicast MBS session based on the stored information; sending a request to remove the unicast QoS flow associated with the multicast MBS session from the PDU session; as well as A request is sent to the UE indicating that the UE is removed from the MBS multicast session.

16. The method according to any one of claims 9 to 15, further comprising: At least one associated cause received in the request from the H-SMF is sent by the V-SMF to the UE.

17. A communication method, the method comprising: receiving, by the NG RAN node, signaling establishing at least one unicast QoS flow to the UE, wherein the signaling indicates, for the at least one unicast QoS flow, that it is related to an MBS multicast session and indicates at least one of: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication by the UE; configuring at least one radio bearer to send the at least one unicast QoS flow to the UE; as well as The received indication for the at least one unicast QoS flow is stored in the multicast MBS session context.

18. A communication method, the method comprising: Receiving, by a Home Session Management Function (H-SMF), a join request for requesting a UE to join a multicast MBS session; The H-SMF receives an N2SM container switching requirement transfer information element from the V-SMF in the first VPLMN, where the N2SM container switching requirement transfer information element includes: multicast MBS session information of at least one MBS session that the UE has joined; as well as When the UE roams in the first VPLMN, the H-SMF determines whether the UE is authorized to continue receiving the multicast MBS session, wherein the determination is based on at least one of the following: Local configuration in a home public land mobile network, information received from an application function during establishment of said multicast MBS session, or User subscription data received from the User Data Manager.

19. The method of claim 18, wherein the determining is performed if the UE was previously located in the home PLMN, or a second VPLMN, and is handed over to the first VPLMN.

20. The method according to any one of claims 18 to 19, further comprising: When it is determined that the UE is not authorized to continue to receive the multicast MBS service in the VPLMN, the H-SMF sends a request to the V-SMF to indicate to the UE that the UE is removed from the MBS multicast session.

21. The method of claim 20, wherein the request indicating to the UE that the UE is removed from the MBS multicast session comprises: Indicates the reason why the UE is not authorized to join the MBS session from the VPLMN it is roaming into, or from any VPLMN.

22. The method according to any one of claims 18 or 21, further comprising: If shared delivery is used in the HPLMN before the inter-PLMN mobility, upon determining that the UE is authorized to continue receiving the multicast MBS service in the VPLMN, the H-SMF sends a request to the V-SMF to establish at least one unicast QoS flow corresponding to the multicast QoS flow information received from the H-MB-SMF.

23. The method of claim 22, wherein the request to establish the at least one unicast QoS flow corresponding to the multicast QoS flow information received from the H-MB-SMF does not indicate a relationship of the at least one unicast QoS flow to the multicast MBS session.

24. The method of claim 22, wherein the request to establish the at least one unicast QoS flow corresponding to the multicast QoS flow information received from the H-MB-SMF indicates at least one of: a relationship between the at least one unicast QoS flow and the multicast MBS session; Instructions for shared delivery should not be used; Separate delivery instructions should be used; or Indication for roaming UE.

25. A communication method, the method comprising: The Handover Required Transfer Information Element for the Home Routed PDU Session anchored at the H-SMF is received by the Visited Session Management Function (V-SMF) from the AMF; Sending the handover request transfer information element to the identified H-SMF; as well as In response to sending the handover requirement delivery information element to the H-SMF, receiving, by the V-SMF, a reply message including at least one of the following: indicating to the UE a request for the UE to be removed from the MBS multicast session, or A configuration of at least one unicast QoS flow is established.

26. The method according to claim 25, further comprising: receiving, by the V-SMF from the H-SMF, a request to the UE indicating that the UE is removed from the MBS multicast session; as well as The V-SMF sends an indication to the UE that the UE is removed from the MBS multicast session.

27. The method according to any one of claims 25 to 26, wherein the indication that the UE is removed from the multicast MBS session sent to the UE comprises at least one associated cause if included in the request received from the H-SMF.

28. The method according to any one of claims 25 to 27, further comprising: The V-SMF receives the reply message from the H-SMF, wherein the reply message includes a configuration for establishing at least one unicast QoS flow; as well as Session management signaling configured to establish the at least one unicast QoS flow is sent by the V-SMF.

29. The method according to any one of claims 25 to 28, further comprising: receiving, by the V-SMF from the H-SMF, the reply message, the reply message comprising: a configuration for establishing at least one unicast QoS flow, and an indication for the at least one unicast QoS flow, the indication indicating at least one of the following: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication that the UE is roaming; and The V-SMF sends session management signaling configured to establish the at least one unicast QoS flow, wherein the session management signaling indicates at least one of the following for the at least one unicast QoS flow: an indication that shared MBS traffic delivery should not be used, an indication that separate delivery should be used, or an indication that the UE is roaming.

30. The method according to any one of claims 25 to 29, wherein the reply message from the H-SMF indicates, for the at least one unicast QoS flow, that it is related to the MBS session, and further comprising: The at least one unicast QoS flow is stored by the V-SMF in association with the MBS session.

31. A communication method, the method comprising: A user equipment roaming in a VPLMN sends a request to join a multicast MBS session; receiving, by the UE, a join request rejection message indicating that the UE is not allowed to access the MBS session when roaming; as well as Sending additional join requests for the MBS session is refrained when roaming.

32. The method according to claim 31, The receiving of the join request rejection message indicating that the UE is not allowed to access the MBS session when roaming includes: receiving a join request rejection message indicating that the UE is not allowed to access the MBS session when roaming in the VPLMN; as well as The suppressing sending of the additional join request for the MBS session when roaming includes: suppressing sending of the additional join request for the MBS session when roaming in the VPLMN.

33. A communication method, the method comprising: A user equipment sends a request to join a multicast MBS session; Roaming in VPLMN; receiving, by the UE, an indication that the UE is removed from the MBS session, the indication having a reason indicating that the UE is not allowed to access the MBS multicast session while roaming; and When roaming, sending additional join requests for the MBS multicast session is suppressed.

34. An apparatus for communication, the apparatus comprising: at least one processor; as well as At least one memory stores instructions, which, when executed by the at least one processor, cause the apparatus to perform at least the method according to any one of claims 1 to 33.

35. A non-transitory computer readable medium comprising program instructions which, when executed by an apparatus, cause the apparatus to perform at least the method according to any one of claims 1 to 33.

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