Access network node, user equipment, access network node method, and user equipment method

Abstract

A method for an access network node is provided. The method includes transmitting, to a User Equipment (UE), a first message that includes an inquiry about the UE's ability to receive Multicast / Broadcast Service (MBS) when the UE is in a Radio Resource Control (RRC)_INACTIVE state, and receiving, from the UE, a second message that includes a list of one or more MBS sessions that the UE can support when the UE is in the RRC_INACTIVE state if the UE has information identifying at least one MBS available to the UE.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system and its devices operating according to the specifications of the Third Generation Partnership Project (3GPP (registered trademark)), or equivalent specifications or derivatives thereof. The present disclosure has a relevant but not specific and exclusive relevance to improvements in session management of multimedia broadcast sessions operating according to so-called "5G" (or "next-generation") systems and the like.

Background Art

[0002] The latest developments of the 3GPP specifications are called "5G" or "New Radio" (NR). These terms refer to evolving communication technologies that support various applications and services. Various details of 5G networks are described, for example, in the "NGMN 5G White Paper" V1.0 by the Next Generation Mobile Networks (NGMN) Alliance, which is available from https: / / www.ngmn.org / 5g-white-paper.html. 3GPP intends to support 5G with so-called 3GPP Next Generation (NextGen) Radio Access Network (RAN) and 3GPP NextGen Core Network (NGC).

[0003] Under 3GPP standards, a base station (e.g., an eNB for 4G or a gNB for 5G) is a node through which communication devices (User Equipment, or "UEs") connect to the core network and communicate with other communication devices or remote servers. For simplicity, this application uses the terms base station or access network node to refer to any such base station. For simplicity, this application uses the terms mobile device, user device or UE to refer to any communication device that can connect to the core network via one or more base stations.

[0004] Communication devices may be mobile communication devices such as, for example, mobile phones, smartphones, user devices, personal digital assistants, laptop / tablet computers, web browsers, e-readers, and / or similar devices. Such mobile (or generally fixed) devices are typically operated by a user. However, the 3GPP standard also enables the connection of so-called “Internet of Things” (IoT) devices (e.g., Narrow-Band IoT (NB-IoT) devices) to the network, which typically include automated equipment such as various measuring instruments, telemetry equipment, monitoring systems, tracking and tracking devices, in-vehicle safety systems, vehicle maintenance systems, road sensors, digital billboards, point-of-sale (POS) terminals, and remote control systems. Effectively, the Internet of Things is a network of devices (or “things”) with appropriate electronics, software, sensors, network connectivity, and / or similar, which enables these devices to collect data and exchange data with each other and with other communication devices. It should be understood that IoT devices are sometimes also called machine-type communication (MTC) devices or machine-to-machine (M2M) devices.

[0005] For simplicity, this application will often refer to mobile devices in its description, but it should be understood that the technology described can be implemented on any communication device (mobile and / or generally stationary) that can connect to a communication network to send / receive data, whether the communication device is controlled by human input or by software instructions stored in memory.

[0006] One of the recent features being developed for the existing 5G framework is called Multicast and Broadcast Services (MBS). This feature aims to enhance the performance of the new 5G radio and 5G core network to enable reliable, low-latency, resource-efficient, and large-scale deployment of diverse multicast and broadcast services. 3GPP is currently specifying details of MBS for media distribution over mobile broadband networks. Some use cases that have been identified as potentially benefiting from MBS include public safety and mission-critical services, Vehicle to Everything (V2X) applications, IPTV, live video, software distribution, and IoT applications to various smartphones, tablets, vehicles, and other mobile (or fixed) devices. MBS is designed to use existing (or already specified) 3GPP infrastructure but can provide more efficient multicast / broadcast traffic delivery than unicast communications using the same infrastructure. Details of the MBS architectural enhancements can be found in 3GPP Technical Specification (TS) 23.247 V17.2.0.

[0007] To facilitate resource-efficient multicast / broadcast service delivery, 3GPP developed NR Broadcast / Multicast as part of Release 17 (Rel-17) of the NR standard, with the aim of enabling common MBS services over 5G telecommunications networks. More specifically, the following two delivery modes for MBS were agreed upon for Rel-17 MBS:

[0008] Distribution mode 1 (multicast only) can handle higher QoS services, and Distribution mode 2 (broadcast only) focuses on lower QoS services.

[0009] While Rel-17 MBS provides the basic functionality to support MBS services, it is acknowledged that it needs to improve resource efficiency and capacity, and address other challenges, in order to meet the demanding use cases proposed for MBS.

[0010] For example, according to Rel-17, the Radio Access Network (RAN) specifies multicast transmission only for UEs in the RRC connected state (sometimes called RRC_CONNECTED mode). Therefore, UEs in other RRC connected states, namely RRC inactive and RRC idle states (sometimes called RRC_INACTIVE mode and RRC_IDLE mode, respectively), will not receive such transmissions. This situation may not fully meet the requirements of, for example, mission-critical services, especially in environments where a cell serves many UEs (e.g., according to TR 23.774). Furthermore, keeping UEs in the RRC connected state at all times is inefficient from both the base station's and the UE's perspectives (e.g., in terms of resource usage, power, etc.).

[0011] The Disclosers acknowledge that there are several problems with the current approach to providing MBS functionality, particularly in terms of UE RRC connectivity state transitions and UE mobility. Therefore, this disclosure seeks to provide methods and related devices to address or at least mitigate the aforementioned problems (or at least some of them). [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] WO2022 / 086121A1 [Patent Document 2] WO2022 / 239690A1 [Non-patent literature]

[0013] [Non-Patent Document 1] 3GPP TS 23.247 [Non-Patent Document 2] 3GPP TS 23.003 [Non-Patent Document 3] 3GPP TS 23.003 [Non-Patent Document 4] 3GPP TS 24.116 [Non-Patent Document 5] 3GPP TR 23.774 [Non-Patent Document 6] 3GPP TS 38.413 [Non-Patent Document 7] 3GPP TS 38.473 [Non-Patent Document 8] 3GPP TS 38.401 [Non-Patent Document 9] 3GPP TS 38.300 [Non-Patent Document 10] 3GPP TS 37.340 [Overview of the project] [Problems that the invention aims to solve]

[0014] The present disclosure aims to provide an apparatus and a related method that at least partially contribute to satisfying one or more of the above-mentioned needs.

Means for Solving the Problem

[0015] According to one aspect, a method for an access network node is provided. The method includes: transmitting a first message indicating the capabilities of user equipment (UE) that receives a multicast / broadcast service (MBS) to a UE in radio resource control (RRC)_INACTIVE state; when the UE has information identifying at least one MBS available to the UE, receiving from the UE a second message indicating one or more MBS sessions that the UE in RRC_INACTIVE state can support; while the UE is in RRC_INACTIVE state, providing at least one MBS corresponding to one or more MBS sessions to the UE.

[0016] According to another aspect, a method for an access network node having a central unit and a distributed unit is provided. The method includes: receiving, by the central unit, an indication of at least one multicast / broadcast service (MBS) session accessible to a user equipment (UE) in radio resource control (RRC)_INACTIVE state from a core network node; transmitting, by the central unit, an indication to the distributed unit; receiving, by the central unit, a response from the distributed unit; transmitting, by the distributed unit, an indication to the UE and includes.

[0017] In another embodiment, a method for a first access network node is provided, and this method is To transmit to User Equipment (UE) served by the first access network node information including a list of ongoing multicast / broadcast service (MBS) sessions of a second access network node adjacent to the first access network node, or a list of adjacent cells / frequency of at least one adjacent access network node having at least one ongoing MBS session. Includes.

[0018] In another embodiment, a method is provided which is performed by a source access network node for the handover of user equipment (UE) to a target access network node, the method being Send a conditional handover request message containing multicast / broadcast service (MBS) configuration information for the UE to the target access network node. Includes.

[0019] In another embodiment, a method is provided which is performed by a target access network node for the handover of user equipment (UE) from a source access network node, and this method is Receiving a conditional handover request message from the source access network node containing multicast / broadcast service (MBS) configuration information for the UE, If there are no ongoing MBS sessions on the target access network node, establish an MBS session with the core network. Includes.

[0020] In another embodiment, a method for a core network node is provided, and this method is Sending a message to further core network nodes that includes instructions for one or more multicast / broadcast service (MBS) sessions accessible by a user equipment (UE) in the Radio Resource Control (RRC)_INACTIVE state. Includes.

[0021] In another embodiment, a method for a core network node is provided, and this method is Sending a message to an access network node containing instructions for one or more multicast / broadcast service (MBS) sessions that a user equipment (UE) in the Radio Resource Control (RRC)_INACTIVE state can access. Includes.

[0022] In another embodiment, a method for User Equipment (UE) is provided, and this method is Receiving a first message from an access network node indicating the ability of a UE in the Radio Resource Control (RRC)_INACTIVE state to receive Multicast / Broadcast Service (MBS), Based on information identifying at least one MBS available to the UE, a second message is sent to the access network node indicating one or more MBS sessions that the UE in the RRC_INACTIVE state can support. While the UE is in the RRC_INACTIVE state, it receives at least one MBS corresponding to one or more MBS sessions. Includes.

[0023] In another embodiment, a method for User Equipment (UE) is provided, and this method is A UE in the Radio Resource Control (RRC)_INACTIVE state receives instructions from a distributed unit of the access network node for one or more multicast / broadcast service (MBS) sessions that it can access. Includes.

[0024] In another embodiment, a method for User Equipment (UE) is provided, and this method is The first access network node receives information from the first access network node that includes a list of ongoing multicast / broadcast service (MBS) sessions of a second access network node adjacent to the first access network node, or a list of adjacent cells / frequency of at least one adjacent access network node having at least one ongoing MBS session. Includes.

[0025] According to another embodiment, an access network node is provided, and the access network node is A means for sending a first message indicating the ability of User Equipment (UE) to receive Multicast / Broadcast Service (MBS) to a UE in Radio Resource Control (RRC)_INACTIVE state, The system includes means for receiving a second message from a UE indicating one or more MBS sessions that a UE in the RRC_INACTIVE state can support, provided that the UE has information identifying at least one MBS available to the UE. While the UE is in the RRC_INACTIVE state, at least one MBS corresponding to one or more MBS sessions is provided to the UE.

[0026] In another embodiment, an access network node having a central unit and distributed units is provided. The central unit is, A means for receiving instructions from a core network node for at least one multicast / broadcast service (MBS) session accessible to a user equipment (UE) in the Radio Resource Control (RRC)_INACTIVE state, A means for transmitting instructions to distributed units, Means for receiving responses from distributed units and Equipped with, The distributed units are Means for sending instructions to the UE It is equipped with.

[0027] In another embodiment, a first access network node is provided, and the access network node is A means for transmitting information to User Equipment (UE) served by the first access network node, including a list of ongoing multicast / broadcast service (MBS) sessions of a second access network node adjacent to the first access network node, or a list of adjacent cells / frequency of at least one adjacent access network node having at least one ongoing MBS session. It is equipped with.

[0028] In another embodiment, a source access network node is provided for the handover of User Equipment (UE) to a target access network node, and the source access network node is A means of sending a conditional handover request message containing multicast / broadcast service (MBS) configuration information for the UE to the target access network node. It is equipped with.

[0029] In another embodiment, a target access network node is provided for the handover of User Equipment (UE) from a source access network node, and the target access network node is A means for receiving a conditional handover request message containing multicast / broadcast service (MBS) configuration information for the UE from a source access network node, If there are no ongoing MBS sessions on the target access network node, what is the means to establish an MBS session with the core network? It is equipped with.

[0030] In another aspect, core network nodes are provided, and the core network nodes are A means of sending a message to further core network nodes containing instructions for one or more multicast / broadcast service (MBS) sessions accessible by user equipment (UE) in the Radio Resource Control (RRC)_INACTIVE state. It is equipped with.

[0031] In another aspect, core network nodes are provided, and the core network nodes are A means of sending a message to an access network node containing instructions for one or more multicast / broadcast service (MBS) sessions that a user equipment (UE) in the Radio Resource Control (RRC)_INACTIVE state can access. It is equipped with.

[0032] In another embodiment, User Equipment (UE) is provided, and the UE is A means for receiving a first message from an access network node indicating the ability of a UE in the Radio Resource Control (RRC)_INACTIVE state to receive Multicast / Broadcast Service (MBS), A means for sending a second message to an access network node indicating one or more MBS sessions that a UE in the RRC_INACTIVE state can support, based on information identifying at least one MBS available to the UE; While the UE is in the RRC_INACTIVE state, it receives at least one MBS corresponding to one or more MBS sessions. Includes.

[0033] In another embodiment, User Equipment (UE) is provided, and the UE is A means of receiving instructions from a distributed unit of an access network node for one or more multicast / broadcast service (MBS) sessions that a UE in the Radio Resource Control (RRC)_INACTIVE state can access. It is equipped with.

[0034] In another embodiment, User Equipment (UE) is provided, and the UE is Means for receiving from a first access network node information including a list of ongoing multicast / broadcast service (MBS) sessions of a second access network node adjacent to the first access network node, or a list of adjacent cells / frequency of at least one adjacent access network node having at least one ongoing MBS session. It is equipped with.

[0035] Each feature disclosed herein and / or shown in the drawings (including the terms in the claims) may be incorporated into this disclosure independently of (or in combination with) any other disclosure and / or illustrated features. In particular, any feature of a claim dependent on a particular independent claim may be introduced into that independent claim in any combination or individually. [Effects of the Invention]

[0036] According to this disclosure, it is possible to provide a method for user equipment, a method for access network nodes, user equipment, and access network nodes.

[0037] Herein, an embodiment of the present disclosure will be described as an example with reference to the attached drawings. [Brief explanation of the drawing]

[0038] [Figure 1] The embodiments of this disclosure schematically illustrate mobile (cellular or wireless) telecommunications systems to which the embodiments may be applied. [Figure 2] The embodiments of this disclosure schematically illustrate mobile (cellular or wireless) telecommunications systems to which the embodiments may be applied. [Figure 3] These are schematic block diagrams of mobile devices that form part of the system shown in Figures 1 and 2. [Figure 4]These are schematic block diagrams of access network nodes (e.g., base stations) that form part of the system shown in Figures 1 and 2. [Figure 5] These are schematic block diagrams of access network nodes (e.g., base stations) that form part of the system shown in Figures 1 and 2. [Figure 6] These are schematic block diagrams of the core network nodes that form part of the system shown in Figures 1 and 2. [Figure 7] Several exemplary ways in which this disclosure may be implemented using the systems shown in Figures 1 and 2 are schematically illustrated. [Figure 8] Several exemplary ways in which this disclosure may be implemented using the systems shown in Figures 1 and 2 are schematically illustrated. [Figure 9] Several exemplary ways in which this disclosure may be implemented using the systems shown in Figures 1 and 2 are schematically illustrated. [Figure 10] Several exemplary ways in which this disclosure may be implemented using the systems shown in Figures 1 and 2 are schematically illustrated. [Modes for carrying out the invention]

[0039] <Overview> Figure 1 schematically illustrates a mobile (cellular or wireless) telecommunications system 1 to which embodiments of the present disclosure may be applied.

[0040] In System 1, users of mobile devices 3 (UEs) can communicate with each other and with other users via base stations 5 and other access network nodes that form a Radio Access Network (RAN). Through these access network nodes, UEs communicate with the associated core network 7 using appropriate 3GPP Radio Access Technology (RAT), for example, Evolved Universal Terrestrial Radio Access (E-UTRA) and / or 5G RAT. It will be understood that several base stations 5 form a (radio) access network, or (R)AN. As those skilled in the art will understand, Figure 1 shows four mobile devices 3 and one base station (included in NG-RAN 5 in Figure 1) for illustrative purposes, but the system, when implemented, typically includes other base stations / (R)AN nodes and / or mobile devices (UEs).

[0041] Each base station 5 controls one or more associated cells (either directly or via other nodes such as home base stations, relays, remote radio heads, distributed units, and / or similar). Base stations 5 that support next-generation / 5G protocols may be called “gNBs” and may form part of the NG-RAN. It will be understood that some base stations 5 may be configured to support both 4G and 5G, and / or any other 3GPP or non-3GPP communication protocols.

[0042] The mobile device 3 and its serving base station 5 are connected via appropriate air interfaces (e.g., so-called "NR" air interfaces, "Uu" interfaces, and / or similar). Adjacent base stations 5 are connected to each other via appropriate inter-base station interfaces (not shown in Figure 1, such as so-called "Xn" interfaces, "X2" interfaces, and / or similar). Base stations 5 are also connected to core network nodes via appropriate interfaces (such as so-called "NG-U" interfaces (for the user plane), so-called "NG-C" interfaces (for the control plane), and / or similar).

[0043] The core network 7 (e.g., EPC in the case of LTE or NGC in the case of NR / 5G) typically includes logical nodes (or “functions”) for supporting communications in the telecommunications system 1, including, among other things, subscriber management, mobility management, billing, security, and call / session management. For example, the core network 7 of a “next-generation” / 5G system includes user plane entities and control plane entities, such as one or more control plane functions (CPFs) and one or more user plane functions (UPFs) 8-3. An example of a CPF is the so-called Access and Mobility Management Function (AMF) 8-1 in 5G, or the Mobility Management Entity (MME) in 4G, which is responsible for handling connectivity and mobility management tasks for mobile device 3. Another exemplary CPF is the so-called Session Management Function (SMF) 8-2, which is responsible for handling communication sessions for mobile device 3, including session establishment, modification, and release.

[0044] Core Network 7 may further include, in addition to other nodes / functions not described in this document, Multicast / Broadcast Session Management Function (MB-SMF)8-4, Multicast / Broadcast User Plane Function (MB-UPF)8-5, Multicast / Broadcast Service Function (MBSF)8-6, Multicast / Broadcast Service Transport Function (MBSTF)8-7, Network Exposure Function (NEF)8-8, Application Function (AF)8-9, Policy Control Function (PCF)8-10, Network Repository Function (NRF)8-11, and Unified Data Management (UDM) entities8-12. Several service-based interfaces are illustrated in Figure 1, specifically as follows:

[0045] Nmbsmf: A service-based interface presented by MB-SMF. Npcf: A service-based interface presented by PCF. Namf: A service-based interface presented by AMF. Nnef: A service-based interface presented by NEF. Nnrf: A service-based interface presented by NRF. Nudm: A service-based interface presented by UDM.

[0046] Furthermore, several reference points are illustrated in Figure 1, specifically as follows:

[0047] N2: Reference point between NG-RAN and AMF. N3: Reference point between NG-RAN and UPF. N3mb: The reference point between RAN and MB-UPF. N4mb: The reference point between MB-SMF and MB-UPF. N6mb: Reference point between MB-UPF and AF / AS. N19mb: Reference point between UPF and MB-UPF. Nmb1: The reference point between MB-SMF and MBSF. Nmb2: The reference point between MBSF and MBSTF. Nmb9: The reference point between MB-UPF and MBSTF. Nmb10: Reference point between MBSF and AF.

[0048] The core network 7 connects to data networks (not shown), such as the Internet and similar networks based on the Internet Protocol (IP), via UPF 8-3.

[0049] Various network operators deploy their own base stations 5 and associated core networks 7 to provide services in a given area (e.g., a country). Each network is sometimes called a Public Land Mobile Network (PLMN) and is uniquely identified by its PLMN identifier (PLMN ID). The PLMN ID consists of a Mobile Country Code (MCC) and a Mobile Network Code (MNC). Each subscriber (i.e., UE 3) belongs to a PLMN and uses the services of the associated core network 7 and access network (i.e., base station 5).

[0050] For example, multicast and broadcast services (MBS) functionality, which provides resource-efficient transmission to multiple end users requiring the same service, may be provided to UE 3 via a serving base station 5 and associated core network nodes such as UPF 8-3 and SMF 8-2. UPF 8-3 may be an MBS-specific UPF, in which case it may be called MB-UPF 8-5 (for example, specialized for providing MBS functionality). Similarly, SMF 8-2 may be an MBS-specific SMF, in which case it may be called MB-SMF 8-4. However, it should be understood that any suitable UPF / SMF may be used for MBS.

[0051] Each UE 3 interested in MBS monitors the system information broadcast by the base station 5 and determines the resources used for the relevant control channel and data channel (MCCH and MTCH, respectively). The base station 5 also broadcasts a unique identifier (MBS session ID or temporary mobile group identity, TMGI) for each MBS session provided in its cell. When a UE 3 finds its PLMN ID in the system information for a given cell, it is granted access to that cell.

[0052] TMGI is an MBS session identifier that uniquely identifies a specific MBS service. TMGI has three parts: the MBMS service ID part, the Mobile Country Code (MCC) part, and the Mobile Network Code (MNC) part. 3GPP TS 38.413, Section 9.3.1 defines the three parts of TMGI as follows: 1) A 3-octet MBMS service ID. The MBMS service ID consists of a 6-digit fixed-length hexadecimal number ranging from 000000 to FFFFFF. The MBMS service ID uniquely identifies the MBMS bearer service within the PLMN. The structure of the MBMS service ID for services in receive-only mode is specified in 3GPP TS 24.116. 2) A three-digit Mobile Country Code (MCC). While an MCC uniquely identifies the country where a Broadcast-Multicast Service Centre (BM-SC) is located, an MCC value of 901 does not identify any particular country and is assigned globally by the International Telecommunication Union (ITU). 3) A two- or three-digit Mobile Network Code (MNC) (as assigned to the PLMN by the National Numbering Plan Administrator). The MNC identifies the PLMN to which BM-SC belongs, however, an MNC value of 56 when the MCC value is 901 does not identify any PLMN. For details on the operation of TMGI, see 3GPP TS 23.246.

[0053] 3GPP TS 23.003 defines the parts of the PLMN ID as follows: 1) A three-digit Mobile Country Code (MCC). The MCC uniquely identifies the country where the mobile subscription is located. 2) A two- or three-digit Mobile Network Code (MNC) for 3GPP network use (as assigned to PLMN by the National Numbering Plan Administrator). The MNC identifies the home PLMN of a mobile subscription in its country of origin, or, together with the MCC and Network Identifier (NID), identifies the Stand-alone Non-Public Network (SNPN) of a mobile subscription. The length of the MNC (two or three digits) depends on the value of the MCC.

[0054] The list of PLMNs supported by a cell is indicated in the relevant system information. Specifically, System Information Block type 1 (SIB1) contains a list of supported PLMNs within the plmn-IdentityInfoList information element (which is included in the so-called CellAccessRelatedInfo information element of SIB1).

[0055] The MBS session establishment procedure is standardized by 3GPP in TS 23.247. Specifically, Section 7.2.1.3 specifies the current procedure for joining a multicast session and related session establishment procedures. In addition, the multicast session management procedure is specified in 3GPP TS 38.413 (according to Section 8.18). The contents of these documents are incorporated into this document by reference.

[0056] As shown in Figure 1, there is one UE 3-1 connected to NG-RAN 5, and groups of three UEs are also connected to NG-RAN 5. UE 3-1 receives data from its MBS session using a point-to-point (PTP) method, while UE group 3-2 receives data from its MBS session using a point-to-multipoint (PTM) method.

[0057] However, as mentioned above, several issues with the current MBS session management procedure need to be addressed, and in particular, the procedure described above currently only applies to UEs that are in an RRC connection state.

[0058] Figure 2 illustrates further details of the core network 7, also showing the interfaces between each network node. As can be seen from the figure, the core network 7 may typically include, among other things (as mentioned above with respect to Figure 1, for example), an Authentication Server Function (AUSF), Unified Data Management (UDM) entities, a Policy Control Function (PCF), and an Application Function (AF). The core network 7 is connected to data networks (DN) 8-14, such as the Internet or similar networks based on the Internet Protocol (IP), (via UPF). The core network 7 may also be connected to Operations and Maintenance (OAM) functions (not shown).

[0059] The following outlines solutions to the current MBS session delivery and management problems. However, we will first discuss some of the nodes that form part of System 1.

[0060] <User Equipment (UE)> Figure 3 is a block diagram illustrating the main components of the mobile device (UE) 3 shown in Figures 1 and 2. As illustrated, the UE 3 includes a transceiver circuit 31 that operates to transmit signals to and receive signals from one or more connected nodes via one or more antennas 33. Although not necessarily shown in Figure 3, the UE 3 naturally has all the usual functions of a conventional mobile device (such as a user interface 35), which may be provided by hardware, software, and firmware, one or any combination thereof, as needed. The controller 37 controls the operation of the UE 3 according to software stored in memory 39. The software may be pre-installed in memory 39 and / or may be downloaded, for example, via a telecommunications network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 41, a communication control module 43, and an MBS module 45.

[0061] The communication control module 43 is responsible for processing (generating / transmitting / receiving) signaling messages and uplink / downlink data packets between UE 3 and other nodes, including (R)AN node 5 and core network nodes. Signaling may include RRC signaling (to and from (R)AN node 5) and / or NG-C / NG-U signaling (to and from core network 7 (via RAN)).

[0062] The MBS module 45 is responsible for processing signaling related to multimedia broadcast services.

[0063] <Access network node (base station)> Figure 4 is a block diagram illustrating the main components of the base station 5 (or similar access network node) shown in Figure 1. As shown, the base station 5 has a transceiver circuit 51 for transmitting signals to and receiving signals from user equipment (such as a mobile device 3) via one or more antennas 53, and a network interface 55 for transmitting signals to and receiving signals from the core network 7 and adjacent base stations. The base station 5 has a controller 57 for controlling the operation of the base station 5 according to software stored in memory 59. The software may be pre-installed in memory 59 and / or downloaded, for example, via the telecommunications network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 61 and at least a communication control module 63. Although not shown in Figure 4, the network interface 55 also typically includes a base station-to-base station interface section (e.g., Xn and / or similar) and a core network interface section (e.g., NG-C / NG-U / N2 / N3).

[0064] The communication control module 63 is responsible for processing (generating / transmitting / receiving) signaling between the base station 5 and other nodes such as the UE 3 and core network nodes. Such signaling may include, for example, control data for managing the operation of the mobile device 3 (e.g., non-access layer, radio resource control, system information, paging, and / or similar). The signaling may include signaling that configures the UE 3 to receive MBS sessions and signaling that configures other nodes to provide MBS sessions. It will be understood that the communication control module 63 may include multiple submodules (or "layers") to support specific functions. For example, the communication control module 63 may include a PHY submodule, MAC submodule, RLC submodule, PDCP submodule, SDAP submodule, IP submodule, RRC submodule, and so on.

[0065] In a 5G architecture, the internal structure of a base station (gNB or en-gNB) can be divided into two parts known as the Central Unit (CU) and the Distributed Unit (DU), connected by an F1 interface. In this "divided" architecture, the "upper" CU layer (not necessarily or exclusively, e.g., PDCP) and the "lower" DU layer (not necessarily or exclusively, e.g., RLC / MAC / PHY) can be implemented separately. Therefore, for example, in each gNB, the lower-layer DU functions can be kept locally, while the upper-layer CU functions of some gNBs can be centrally implemented (e.g., by a single processing unit or in a cloud-based or virtualized system).

[0066] As shown in Figure 5, if base station 5 comprises a distributed base station (gNB or en-gNB), the network interface 55 also includes E1 and F1 interfaces (F1-C for the control plane and F1-U for the user plane) for transmitting signals between the respective functions of the distributed base station. In this case, the software stored in base station 5 also includes at least one of the gNB-CU-CP module 5C, gNB-CU-UP module 5U, and gNB-DU module 5D. If present, the gNB-CU-CP module 5C hosts the control plane portions of the RRC and PDCP layers of the distributed base station (gNB or en-gNB). If present, the gNB-CU-UP module 5U hosts the user plane portions of the PDCP and SDAP layers of the distributed gNB, or the user plane portion of the PDCP layer of the distributed en-gNB. If present, the gNB-DU module 5D hosts the RLC, MAC, and PHY layers of the distributed base station (gNB or en-gNB).

[0067] Those skilled in the art will understand that the central unit (e.g., 5C and / or 5U) may be implemented and physically located together with the base stations, or may be implemented remotely as a single physical element, or as a cloud-based or virtualized system. It will also be understood that a single central unit may serve multiple base stations 5.

[0068] <Core Network Node> Figure 6 is a block diagram illustrating the main components of a core network node shown in Figures 1 and 2 (e.g., AMF 8-1, SMF 8-2, UPF 8-3, etc.). As illustrated, the core network node includes transceiver circuitry 71 that operates to transmit and receive signals from other network nodes (directly or indirectly) via a network interface 75. Signals may be transmitted to and received from one or more UEs 3 via base stations 5 or other (R)AN nodes as needed. The network interface 75 typically includes an appropriate base station interface (e.g., S1 / NG-C / NG-U). A controller 77 controls the operation of the core network node according to software stored in memory 79. The software may be pre-installed in memory 79 and / or downloaded, for example, via a telecommunications network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 81, a communications control module 83, and an optional MBS module 85.

[0069] The communication control module 83 is responsible for processing (generating / transmitting / receiving) signaling between the core network node and other nodes such as UE 3, (R)AN node, and other core network nodes.

[0070] For example, if located within MB-SMF 8-4 or MB-UPF 8-6, the MBS module 85 is responsible for handling signaling related to multimedia broadcast services (control signaling and / or MBS traffic). This signaling may include signaling related to providing MBS sessions via RAN / base stations, and signaling for configuring other nodes to provide MBS sessions via RAN / base stations.

[0071] <Detailed explanation> As mentioned above, MBS session management has several problems. The following detailed explanation shows some solutions to these problems.

[0072] 1. RRC_INACTIVE mode configuration According to Rel-17 MBS, when an MBS session is activated, RAN node 5 sends a paging message containing a TMGI list that identifies each MBS session available through RAN node 5. If UE 3 is interested in an MBS session that has a TMGI on the list, the current standard specifies that UE 3 must transition to RRC_CONNECTED mode to receive MBS transmissions. However, a UE operating according to the latest version of the 3GPP NR standard (Release 18) can be in any one of three expected RRC modes (connection states) with its serving base station:

[0073] 1) RRC_CONNECTED, 2) RRC_INACTIVE, or 3) RRC_IDLE.

[0074] The RRC_INACTIVE state is one in which the UE can quickly return to the RRC_CONNECTED state, and it has been proposed that the UE should be able to receive MBS transmissions while in the RRC_INACTIVE state (however, it does not have the high service reliability that is normally guaranteed when in the RRC_CONNECTED state and permitted by the MBS service). Therefore, if UE 3 can transition to RRC_INACTIVE mode, it does not need to transition to RRC_CONNECTED mode if the MBS service permits the UE to access the MBS service while in RRC_INACTIVE mode. Not transitioning to / not remaining in RRC_CONNECTED mode is mutually beneficial for the network and the UE, as it saves resources on both the network and the UE side.

[0075] In this regard, Figure 7 illustrates the procedure between UE 3 of telecommunications system 1 and RAN node 5 (such as gNB), which allows the network to determine UE 3's ability to support RRC_INACTIVE mode configuration in the context of an MBS session. In step 1, RAN node 5 sends a query to determine UE's ability to receive MBS in RRC_INACTIVE mode. (This query may be called a UE RRC_INACTIVE support query.) This query may be sent in a dedicated RRC message (e.g., UEcapablityenquiry, RRCSetupComplete, or another appropriate message), in a paging message, in a System Information Block (SIB), or in signaling on a multicast control channel (e.g., MBMS Control Channel (MCCH), MBS Control Channel (MCCH)).

[0076] In step 2, UE 3 reports whether it can support the RRC_INACTIVE state. This response is sometimes called the UE RRC_INACTIVE support report and may include a list of MBS sessions that the UE is interested in receiving. Upon receiving this information, the network can beneficially configure RRC_INACTIVE mode support for the UE and manage the relevant MBS sessions for the UE, taking the received report into consideration.

[0077] To notify UE 3 that it does not need to transition to the RRC_CONNECTED state to receive MBS transmissions, the current procedure needs to be changed.

[0078] The first option is to associate an instruction with each TMGI in the TMGI list broadcast by RAN node 5. If this instruction is set to, for example, "yes", then a UE operating according to the latest version of the standard (i.e., Release 18 (Rel-18) UE) will transition to RRC_CONNECTED mode if the UE wishes to receive its MBS transmission. On the other hand, if this instruction is set to, for example, "no", then the UE will not transition to RRC_CONNECTED mode if it wishes to receive its MBS transmission. The structure of the modified paging message can take the following form:

[0079] Paging::=SEQUENCE { Paging-v1700-IEs::=SEQUENCE { pagingRecordList-v1700 PagingRecordList-v1700 OPTIONAL,--Need N pagingGroupList-r17 PagingGroupList-r17 OPTIONAL, } PagingGroupList-r18::=SEQUENCE(SIZE(1..maxNrofPageGroup-r18))OF MBSService MBSService::=SEQUENCE { TMGI RRCCONNECTEDINDICATION-R18 }

[0080] Therefore, in this case, this instruction tells the UE whether to allow the corresponding MBS service to receive MBS services in the RRC_INACTIVE state, so that a UE that can operate in the RRC_INACTIVE state can determine whether to transition to the RRC_CONNECTED state based on one or more instructions for one or more MBS services that it wants to receive.

[0081] According to the alternative option, the UE may instead be configured not to transition to RRC_CONNECTED mode even if the paging message contains a TMGI of interest to the UE.

[0082] 2. RRC state transitions An MBS-enabled UE can transition from the RRC_CONNECTED state to the RRC_INACTIVE state to save power and increase serving cell capacity, for example (by minimizing the signaling overhead associated with keeping the UE in the RRC_CONNECTED state).

[0083] Similarly, an MBS-enabled UE can transition from the RRC_INACTIVE state to the RRC_CONNECTED state when the UE moves to the edge of a serving cell and the network establishes another point-to-point (PTP) segment of an MBS radio bearer (MRB) to improve the reliability of the MBS services the UE receives. Furthermore, if the UE is ready to reselect an adjacent cell, but the adjacent cell does not support MBS services in the RRC_INACTIVE state because it is operating according to an older release standard (for example, if the adjacent RAN node is operating according to Release 17), the UE must transition to the RRC_CONNECTED state to maintain MBS services when selecting the adjacent cell.

[0084] One way to control these issues is for RAN node 5 to configure UEs in the RRC_INACTIVE state with the StateTransitConfig parameter, which sets the RRC state transition threshold used to control the transition between the RRC_INACTIVE state and the RRC_CONNECTED state (detailed below). The StateTransitConfig parameter can be provided to the UE in the SIB, on a multicast control channel (e.g., MCCH), or by a paging message.

[0085] Accordingly, if the UE is instead in the RRC_CONNECTED state, the StateTransitConfig parameter may be configured by RAN node 5 and provided to the UE by dedicated RRC signaling. If the UE has already received the StateTransitConfig parameter in the SIB, on the MCCH, or via a paging message (i.e., if the UE received this parameter while in the RRC_INACTIVE state), the StateTransitConfig parameter provided by dedicated RRC signaling takes precedence, thereby overriding the StateTransitConfig parameter received while the UE was in the RRC_INACTIVE state.

[0086] The thresholds included in the StateTransitConfig parameter may include the following conditions: Conditions for changing from RRC_CONNECTED to RRC_INACTIVE RSRP>RSRPConnectedtoInactivethres RSRQ>RSRQConnected to Inactive thres Conditions for changing from RRC_INACTIVE to RRC_CONNECTED RSRP <RSRPInactivetoConnectedthres RSRQ <RSRQInactivetoConnectedthres Here, RSRP is the reference signal received power, and RSRQ is the reference signal received quality. These are measured values ​​of the received signal measured by the UE and are well known to those skilled in the art.

[0087] Since the StateTransitConfig parameter can be associated with each TMGI, the requirements for transitioning between RRC states may vary depending on the MBS service the UE receives. The StateTransitConfig parameter can be communicated to the UE in a message carrying the configuration (for example, RRC_INACTIVE-SUPPORTIVE-configuration). The structure of such a message can take the following form:

[0088] RRC_INACTIVE-SUPPORTIVE-configuration::=SEQUENCE { MBSservice TMGI StateTransitConfig }

[0089] The following describes further embodiments for controlling RRC state transitions in a segmented MRB (MBS Radio Bearer) configuration. In this regard, it may be beneficial for the UE to transition from the RRC_INACTIVE state to the RRC_CONNECTED state to ensure the reliability of a desired MBS service when the Reference Signal Received Power (RSRP) / Reference Signal Received Quality (RSRQ) of a point-to-multipoint (PTM) section does not meet a configured threshold. To facilitate this state transition, the UE can establish an RRC connection to the network and notify the network in a modified RRCSetupComplete message which one or more MBS services require the reliability improvement achieved, for example, by the network configuring an additional PTP section in the MRB. The structure of the modified RRCSetupComplete can take the following form.

[0090] RRCSetupComplete::=SEQUENCE { rrc-transition Identifier RRC-transition Identifier, criticalExtensions CHOICE { rrcSetupComplete RRCSetupComplete-IEs, criticalExtensionsFuture SEQUENCE {} } } o RRCSetupComplete-IEs::=SEQUENCE { selectedPLMN-Identity INTEGER(<=maxPLMN), registeredAMF RegisteredAMF OPTIONAL, guami-Type ENUMERATED {native,mapped} OPTIONAL, ………………. } OPTIONAL, } o RRCSetupComplete-v1810-IEs::=SEQUENCE { MBS-reliability-r18 TMGI-list OPTIONAL,or MBS-reliability-r18 MRB-id-list OPTIONAL, } o}

[0091] 3. MBS Session Establishment<W Note: There seems to be an issue with the "INTEGER(1..maxPLMN)" in the original. It's not clear what "maxPLMN" is supposed to be. I've changed it to "INTEGER(<=maxPLMN)" for a more general and correct translation. If there's a specific meaning for "maxPLMN" that I'm not aware of, this translation might need adjustment. Also, the "<W " at the end seems to be an incorrect tag. It should probably be " " based on the sequence.The MBS session establishment procedure and related management procedure are specified in 3GPP TS 23.247. One such procedure, specified in Section 7.2.1.4 of this standard, concerns "establishing joint distribution to RAN nodes" (joint distribution meaning the distribution of MBS services to UEs via multicast transmission). However, the current procedure does not inform the gNB-CU and one or more gNB-DUs whether UE 3 is permitted to operate in the RRC_INACTIVE state for this particular MBS session. Therefore, a modified signaling diagram for "establishing joint distribution to RAN nodes" that addresses the above-mentioned problem is presented in Figure 8 and described below.

[0092] In Step 1, NG-RAN node 5 decides to establish co-delivery for a multicast MBS session when serving to at least one UE 3 within the multicast MBS session. For location-dependent services, NG-RAN node 5 must establish co-delivery for the location-dependent content of the multicast MBS session when serving to at least one UE assigned to the MBS session ID and area session ID.

[0093] Next, in step 2, NG-RAN sends an N2 MBS session request message to AMF 8-1 (including one or more of the following: MBS session ID, [Area Session ID], N2 SM information ([Unicast DL Tunnel Information])). If NG-RAN node 5 is configured to use unicast transport for co-distribution, NG-RAN node 5 assigns a GTP tunnel endpoint and provides unicast DL tunnel information in the request, including the GTP tunnel endpoint and the NG-RAN node 5 address. For location-dependent MBS services, NG-RAN node 5 also provides the Area Session ID.

[0094] In step 3, AMF 8-1 selects an MB-SMF 8-4 to serve the multicast MBS session, for example, using the NRF discovery service or locally stored information. AMF 8-1 calls an Nmbsmf_MBSSession_ContextUpdate request to MB-SMF 8-4 (including one or more of the MBS session ID, [area session ID], and N2 SM information). AMF 8-1 stores information for one or more NG-RAN nodes (e.g., NG-RAN node IDs) for subsequent signaling related to the multicast MBS session.

[0095] Step 4 is indicated by a dotted line and is conditional on MB-SMF 8-4 receiving unicast DL tunnel information in Step 3. If so, MB-SMF 8-4 configures MB-UPF 8-5 to send multicast data for the multicast MBS session (or location-dependent content of the multicast MBS session if an area session ID is received) to its GTP tunnel endpoint via unicast transport.

[0096] Continuing with step 5, MB-SMF 8-4 stores information about AMF 8-1 (e.g., AMF ID) in the MBS multicast MBS session context (or the location-dependent portion of the multicast MBS session context if an area session ID is received) to enable subsequent signaling to AMF 8-1.

[0097] As outlined in TS 23.247, the above steps remain unchanged in relation to the current procedure. Steps 6-8 below represent modifications and additions to the corresponding steps currently outlined in TS 23.247 in order to resolve the issues identified above. Turning to step 6, MBS-SMF 8-4 sends a message to AMF 8-1 (sometimes called the Nmbsmf_MBSSession_ContextUpdate response message) that includes the MBS session RRC_INACTIVE authorization directive and TMGI, in addition to any other appropriate parameters. The MBS session RRC_INACTIVE authorization directive indicates whether the TMGI is authorized for the UE to receive the corresponding MBS service in an RRC_INACTIVE state. Furthermore, if MB-SMF 8-4 did not receive unicast DL tunnel information in step 3, MB-SMF 8-4 provides multicast DL tunnel information including the transport multicast address (e.g., Lower Layer Source Specific IP Multicast (LL SSM)) and the GTP tunnel endpoint for the co-distribution multicast transport.

[0098] Next, in step 7, AMF 8-1 sends an N2 MBS message to NG-RAN node 5 containing the MBS session RRC_INACTIVE authorization directive and TMGI, along with any additional relevant parameters. Finally, in step 8, the NG-RAN gNB provides the UE 3 with the MBS session RRC_INACTIVE authorization directive and TMGI, for example, by a System Information Block (SIB) (or alternatively, on a Multicast Control Channel (MCCH), in a paging message, or in an RRCRelease message). As a result of UE 3 receiving the MBS session RRC_INACTIVE authorization directive and associated TMGI, UE 3 can utilize the MBS service corresponding to this TMGI in the RRC_INACTIVE state, thereby beneficially avoiding the need for UE 3 to transition to the RRC_CONNECTED state.

[0099] To ensure that the multicast context is set up correctly, the current multicast context setup (as defined in Section 8.14.6 of TS 38.473) is modified to include the MBS session RRC_INACTIVE authorization directive, as shown in Figure 9. As illustrated in Step 1 of Figure 9, gNB-CU 5A sends a message (sometimes called a MULTICAST CONTEXT SETUP REQUEST) to gNB-DU 5B that includes the MBS session RRC_INACTIVE authorization directive and associated TMGI received in Step 7 of Figure 8. In Step 2, gNB-DU 5B acknowledges receipt of the message sent by gNB-CU 5A by sending a message (sometimes called a MULTICAST CONTEXT SETUP RESPONSE message) to gNB-CU 5A. Therefore, following the procedure described above, both gNB-CU 5A and one or more gNB-DU 5B know whether the UE is permitted to operate in RRC_INACTIVE mode for the MBS session, and thus the gNB-CU can configure the appropriate MRB for the RLC entities in UE 3 and gNB-DU.

[0100] 4. RRC_INACTIVE Mode Mobility As described above in accordance with Release 17 of the MBS standard, a UE must transition to the RRC_CONNECTED state to register with the MBS service on the core network. However, according to the more recent Release 18, after the registration procedure, the UE is free to transition to the RRC_INACTIVE state (in accordance with the conditions described above in the embodiment titled “RRC State Transition”). It should be understood that when a UE operating in the RRC_INACTIVE state is in transit and performing cell reselection, the UE does not need to transition to RRC_CONNECTED mode to achieve cell reselection. However, if the adjacent cell that the UE wants to reselect (and therefore camp) does not have an ongoing PTM MBS session for the UE to receive at the camping cell, the UE will transition to the RRC_CONNECTED state.

[0101] According to Release 17, only UEs in the RRC_CONNECTED state are supported for multicast, so multicast configurations are not scheduled in MCCH, but instead are scheduled in the RRCReconfiguration message, which is only available when the UE is in the RRC_CONNECTED state (the RRCReconfiguration message is used for handover and provides all neighbor cell information). Therefore, a solution is provided below that facilitates providing multicast configurations for UEs operating in RRC_INACTIVE mode without requiring an RRC state transition.

[0102] According to this embodiment, a new channel (multicast channel, MCCH) is provided for UEs operating in the RRC_INACTIVE state, and this channel can therefore provide multicast configuration for RRC_INACTIVE UEs. Since RRC_INACTIVE UEs can still receive System Information Blocks (SIBs), the new MCCH is scheduled in the SIB, and therefore, in the following description, references to SIB-MCCH refer to UEs that read the SIB to obtain MCCH scheduling.

[0103] Regarding handling the mobility of UEs in the RRC_INACTIVE state, in the first example, the serving cell provides a list of neighboring cell MBS sessions in progress in the SIB-MCCH (or the SIB itself). This allows the RRC_INACTIVE UE to know which neighboring cell has an MBS session of interest to the UE. However, if the UE is interested in an MBS session that is not in progress in the neighboring cell's supported MBS session list, An RRC_INACTIVE UE can transition to the RRC_CONNECTED state. After the handover to the target cell, the UE triggers the MBS join procedure described in Section 7.2.1.3 of 3GPP TS 23.247. However, if there are no ongoing MBS sessions in the target cell, the network will not establish the MBS join procedure described in Section 7.2.1.3 of 3GPP TS 23.247, or A UE operating in the RRC_INACTIVE state can prioritize other adjacent cells that support the desired MBS session. If there are no other cells that support the MBS session, the UE performs normal cell reselection for cells that do not support the MBS session, and then transitions to the RRC_CONNECTED state, triggering the MBS join procedure described in Section 7.2.1.3 of 3GPP TS 23.247. A serving cell can send a list of supported cells / supported frequencies for the desired MBS session to the UE in one of the following messages: a paging message, an RRCRelease message, an RRC-only message, an SIB message, or a message on the MCCH.

[0104] The base station can notify the UE which MBS services are available when the UE is in the RRC_INACTIVE state using the following RRC_INACTIVE-SUPPORTIVE-indication message. RRC_INACTIVE-SUPPORTIVE-indication::=SEQUENCE { MBSservice TMGI RRCINACTIVESUPPORTIVE RRCINACTIVESUPPORTIVE(true,false) }

[0105] In the second example, the serving cell broadcasts only a list of neighboring cells / frequencies that have ongoing MBS services (on its SIB-MCCH). When a UE is considering re-selecting a neighboring cell, the UE can check from the information broadcast by its currently serving cell whether the neighboring cell has ongoing MBS services. If it does, the UE reads the neighboring cell's MCCH to obtain a list of MBS sessions supported by that cell. In this way, the UE can check whether the desired MBS session is running in that neighboring cell before deciding to re-select it.

[0106] If the UE re-selects a cell that does not have an ongoing MBS session, the UE transitions to RRC_CONNECTED and triggers the MBS join procedure described in section 7.2.1.3 of TS 23.247.

[0107] 5. Optimizing Handover As specified in the current standard (3GPP TS 38.401, Section 8.9.4), as part of the handover procedure, the source gNB sends a handover request message to the target gNB. The handover request message has an MBS configuration as part of its RRC context information; that is, the handover request message includes details of the MBS session for the UE to be handed over to the target cell. Currently, if the target gNB does not have an ongoing MBS session, the target gNB must initiate the MBS session establishment procedure in the target cell in accordance with Section 7.2.1.3 of 3GPP TS 23.247. However, if there is no ongoing MBS session for the UE performing the handover procedure, it will take a long time to establish an MBS session in the target gNB during the handover. The following description, with reference to Figure 10, proposes a solution to this problem (Figure 10 corresponds to a simplified and modified version of the signaling diagram for "inter-gNB handover with gNB-CU-UP change" in Section 8.9.4 of TS 38.401).

[0108] First, referring to step 1 in Figure 10, source gNB-CU-CP 5-1 sends a conditional handover request message to target gNB-CU-CP 5-4. The handover request message includes, as part of the RRC configuration, an MBS configuration for UEs that may be subject to a handover to the target. A conditional handover is a type of pre-handover before the handover conditions are met.

[0109] In step 2, if the target gNB does not have an MBS session, the target gNB-CU-CP 5-4 establishes an MBS session with the core network, usually with the MB-SMF, (for example, according to section 7.2.1.3 of TS 23.247).

[0110] In this way, the target gNB beneficially "pre-establishes" an MBS session if one has not yet been established before the UE's handover actually takes place. This procedure is much faster than using the normal handover procedure, in which the UE must first hand over to the target base station, then request MBS services from the target base station, and then the target base station attempts to establish an MBS session with the core network if one does not yet exist.

[0111] Then, in step 3, gNB-CU-CP 5-4 sends a BEARER CONTEXT SETUP REQUEST message containing UL TNL address information for S1-U or NG-U, and, if necessary, DL TNL address information for X2-U to set up the bearer context at gNB-CU-UP 5-3. For NG-RAN, gNB-CU-CP 5-4 determines the flow-to-DRB mapping and sends the generated SDAP and PDCP configurations to gNB-CU-UP 5-3. Because this handover is conditional, the BEARER CONTEXT SETUP REQUEST message indicates that the included security context should be ignored and that downlink packets should not be initiated until the UE has successfully accessed the target.

[0112] In step 3a, gNB-CU-UP 5-3 responds with a BEARER CONTEXT SETUP RESPONSE message that includes UL TNL address information for F1-U, DL TNL address information for S1-U or NG-U, and, if necessary, UL TNL address information for X2-U or Xn-U.

[0113] Then, in step 4, the F1 UE context setup procedure is performed to set up one or more bearers in gNB-DU 5-2.

[0114] Finally, in step 5, target gNB-CU-CP 5-4 responds to source gNB-CU-CP 5-1 with a HANDOVER REQUEST ACKNOWLEDGE message. Because this handover procedure is conditional, target gNB-CU-CP 5-4 ensures that EARLY STATUS TRANSFER information is transferred to the appropriate gNB-CU-UP 5-3 (for example, via a separate UE-related signaling connection on the Xn interface of each gNB-CU-UP).

[0115] <Examples of corrections and alternatives> Detailed embodiments have been described above. As those skilled in the art will understand, several modifications and substitutions can be made to those embodiments, further benefiting from the disclosures embodied in the above embodiments. Some of these substitutions and modifications are described here only as illustrative examples.

[0116] The above explanation refers to MBS for simplicity. However, MBS functionality is sometimes also called Multimedia Broadcast / Multicast Services (MBMS) functionality. Base stations for 5G / NR communication systems are generally called New Radio Base Stations (NR-BS) or gNBs, but it should be understood that they may also be referred to using the term eNB (or 5G / NR eNB), more typically associated with Long Term Evolution (LTE) base stations (commonly also called "4G" base stations). 3GPP TS 38.300 V16.7.0 and 3GPP TS 37.340 V16.7.0 specify, among other things, the following nodes:

[0117] A node that provides protocol termination for the NR user plane and control plane toward the gNB:UE and is connected to the 5G Core Network (5GC) via the NG interface. ng-eNB: A node that provides protocol termination for the E-UTRA user plane and control plane toward the UE, and is connected to 5GC via the NG interface. A node that provides protocol termination for the NR user plane and control plane toward En-gNB:UE, and functions as a secondary node in E-UTRA-NR Dual Connectivity (EN-DC). NG-RAN node: Either gNB or ng-eNB.

[0118] It will be understood that the above embodiments may be applicable to 5G New Radio and LTE systems (E-UTRAN), as well as any future generation systems. Base stations supporting the E-UTRAN / 4G protocol may be referred to as "eNBs," and base stations supporting the NextGeneration / 5G protocol may be referred to as "gNBs." It will be understood that some base stations may be configured to support both 4G and 5G protocols, and / or any other 3GPP or non-3GPP communication protocols.

[0119] For ease of understanding, the above description assumes that the UE, access network node, and data network node have several separate modules (such as a communications control module). These modules may be provided in this way in certain applications, for example, where an existing system is modified to implement the disclosure. However, in other applications, such as a system designed from the outset with the features of the present invention in mind, these modules may be integrated into the overall operating system or code and therefore may not be identifiable as separate entities. These modules may be implemented in software, hardware, firmware, or a combination thereof.

[0120] Each controller may include, for example (but not limited to), one or more hardware-implemented computer processors, microprocessors, central processing units (CPUs), arithmetic logic units (ALUs), input / output (IO) circuits, internal memory / cache (programs and / or data), processing registers, communication buses (e.g., control buses, data buses and / or address buses), direct memory access (DMA) functions, hardware or software-implemented counters, pointers and / or timers, and / or similar, as well as any suitable form of processing circuitry.

[0121] In the embodiments described above, several software modules have been described. As those skilled in the art will understand, the software modules may be provided in compiled or uncompiled form and may be supplied to the UE, access network nodes, and data network nodes as signals via a computer network or on a recording medium. Furthermore, the functions performed by some or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred because it facilitates the updating of the UE, access network nodes, and data network nodes to update their functions.

[0122] The above embodiments are also applicable to “non-mobile” or generally fixed user devices.

[0123] Information may be received via the MBS Control Channel (MCCH) or by application layer procedures.

[0124] The core network functionality may include at least one of the following: functionality for access and mobility management, and functionality for session management.

[0125] Various other modifications are obvious to those skilled in the art and will not be described in further detail here.

[0126] While this disclosure is described with reference to exemplary embodiments, it is not limited thereto. Various modifications to the structure and details of this disclosure can be understood by those skilled in the art within the scope of this disclosure.

[0127] This application is based on UK Patent Application No. 2211642.0, filed on 9 August 2022, and claims the benefit of that priority, the disclosure of which is incorporated herein by reference in its entirety.

[0128] Programs can be stored and provided to computer devices using any type of non-temporary computer-readable medium. Non-temporary computer-readable medium includes any type of tangible storage medium. Examples of non-temporary computer-readable medium include magnetic storage media (floppy disks, magnetic tapes, hard disk drives, etc.), magneto-optical storage media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memory (mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, RAMs (Random Access Memory), etc.). Programs may also be provided to computer devices using any type of temporary computer-readable medium. Examples of temporary computer-readable medium include electrical signals, optical signals, and electromagnetic waves. Temporary computer-readable medium can be provided to computer devices via wired communication lines such as electric wires and optical fibers, or via wireless communication lines.

[0129] For example, all or part of the exemplary embodiments disclosed above may be described as follows, but are not limited thereto. (Note 1) A method for an access network node, Sending a first message to the User Equipment (UE) that includes an inquiry about the UE's ability to receive Multicast / Broadcast Service (MBS) when the User Equipment (UE) is in the Radio Resource Control (RRC)_INACTIVE state, The UE receives a second message from the UE containing a list of one or more MBS sessions that the UE can support when the UE is in the RRC_INACTIVE state, provided that the UE has information that identifies at least one MBS available to the UE. Methods that include... (Note 2) The first message is transmitted as a dedicated RRC message, paging message, System Information Block (SIB), or over a multicast control channel, as described in Appendix 1. (Note 3) The first message is a UE RRC_INACTIVE support inquiry message, as described in Appendix 1 or Appendix 2. (Note 4) The second message is the UE RRC_INACTIVE support report message, as described in Appendix 3. (Note 5) A method for an access network node, Send a paging message to a User Equipment (UE) in Radio Resource Control (RRC)_INACTIVE state that contains a list of at least one Temporary Mobile Group Identity (TMGI) associated with each available Multicast / Broadcast Service (MBS) session. Includes, The paging message is Each instruction associated with each TMGI in the list, and each instruction is, Whether the UE needs to transition to the RRC_CONNECTED state to receive the respective MBS session associated with each TMGI, or Whether the UE can remain in the RRC_INACTIVE state in order to receive the respective MBS sessions associated with each TMGI. Each instruction, or Instructions to configure a UE (Unified Element) so that it does not transition to the RRC_CONNECTED state in response to receiving a paging message, if the UE is a Release 18 or later UE. A method that includes this. (Note 6) The instructions are RRCCONNECTEDINDICATION-R18 instructions, as described in Appendix 5. (Note 7) A method for an access network node, This includes using a Multicast / Broadcast Service (MBS) with a Temporary Mobile Group Identity (TMGI) to send parameters associated with the TMGI to the User Equipment (UE), where the parameters indicate conditions that, if met, cause the UE to transition from the Radio Resource Control (RRC)_CONNECTED state to the RRC_INACTIVE state, or from the RRC_INACTIVE state to the RRC_CONNECTED state. method. (Note 8) The parameters are System Information Blocks (SIBs) sent to the UE over a multicast channel, either in paging messages or via dedicated RRC signaling, as described in Appendix 7. (Note 9) The condition is the method described in Appendix 7 or 8, including whether one or more received signal measurements are greater than or less than a threshold level. (Note 10) The conditions for transitioning the UE from the RRC_CONNECTED state to RRC_INACTIVE include whether the Reference Signal Received Power (RSRP) measured by the UE is greater than a first threshold, and / or whether the Reference Signal Received Quality (RSRQ) measured by the UE is greater than a second threshold, or The conditions for transitioning the UE from the RRC_CONNECTED state to RRC_INACTIVE include whether the Reference Signal Received Power (RSRP) measured by the UE is less than a third threshold, and / or whether the Reference Signal Received Quality (RSRQ) measured by the UE is less than a fourth threshold. The method described in Appendix 9. (Note 11) The parameter is the StateTransitConfig parameter, as described in any one of the methods in appendices 7 through 10. (Note 12) Instructions are sent as part of RRC_INACTIVE-SUPPORTIVE-configuration, in the manner described in any one of appendices 7 through 11. (Note 13) A method for an access network node, The MBS Radio Bearer (MRB) provides multicast / broadcast services (MBS) to user equipment (UE), Receiving a notification from the UE requesting improved reliability of the MBS service, Provisioning for improved reliability, Methods that include... (Note 14) Notifications are received via the RRCSetupComplete message, as described in Appendix 13. (Note 15) The method described in Appendix 13 or 14, wherein the notice includes a list of at least one TMGI that is required to improve reliability for an MBS service associated with at least one TMGI in the list, or the notice includes a list of at least one MBS Radio Bearer (MRB) associated with an MBS service that requires improved reliability. (Note 16) Reliability improvements include the method described in any one of Appendix 13 to 15, which involves the access network node provisioning an additional point-to-point (PTP) segment with MRB. (Note 17) A method for an access network node having a central unit and distributed units, The central unit receives instructions from the core network node for at least one multicast / broadcast service (MBS) session that the User Equipment (UE) can access when the UE is in the Radio Resource Control (RRC)_INACTIVE state, The central unit transmits instructions to the distributed units, The central unit receives responses from the distributed units, The distributed unit transmits instructions to the UE, Methods that include... (Note 18) The instructions are as described in Appendix 17, including an RRC_INACTIVE authorization directive and a Temporary Mobile Group Identity (TMGI) for each of at least one MBS sessions. (Note 19) A method for core network nodes, Send a message to a second core network node containing instructions for one or more multicast / broadcast service (MBS) sessions that the User Equipment (UE) can access when the UE is in the RRC_INACTIVE state. Methods that include... (Note 20) The method described in Appendix 19, where the core network node is a multicast / broadcast session management function MB-SMF, and the second core network node is an access management function AMF. (Note 21) The message is the Nmbsmf_MBSSession_ContextUpdate response message, as described in Appendix 19 or 20. (Note 22) A method for core network nodes, Sending a message to an access network node containing instructions for one or more multicast / broadcast service (MBS) sessions that a User Equipment (UE) can access when the UE is in the Radio Resource Control (RRC)_INACTIVE state. Methods that include... (Note 23) The core network node is an access management function (AMF) as described in Appendix 22. (Note 24) The message is an N2 MBS message, as described in Appendix 22 or 23. (Note 25) A method for a first access network node, To transmit to User Equipment (UE) served by the first access network node information including a list of ongoing multicast / broadcast service (MBS) sessions of a second access network node adjacent to the first access network node, or a list of adjacent cells / frequency of at least one adjacent access network node having at least one ongoing MBS session, Methods that include... (Note 26) Transmission is the method described in Appendix 25, which involves transmitting information via a system information block or a multicast control channel. (Note 27) The serving cell sends the supported cell / supported frequency list of the MBS session list to the UE in one of the following: a paging message, an RRC release message, an RRC-only message, an SIB message, or a message on the MCCH, as described in Appendix 25 or 26. (Note 28) A method performed by a source access network node for the handover of user equipment (UE) to a target access network node, Send a conditional handover request message containing MBS configuration information for the UE to the target access network node. Methods that include... (Note 29) A method performed by a target access network node for the handover of user equipment (UE) from a source access network node, Receiving a conditional handover request message containing MBS configuration information for the UE from the source access network node, Establishing an MBS session with the core network when there are no ongoing MBS sessions on the target access network node, Methods that include... (Note 30) Establishing is performed before the UE is handed over to the target access network node, as described in Appendix 29. (Note 31) Establishing is done in response to the receipt of a conditional handover request, as described in Appendix 29 or 30. (Note 32) A method for User Equipment (UE), Receiving a first message from an access network node that includes an inquiry about the UE's ability to receive Multicast / Broadcast Service (MBS) when the UE is in the Radio Resource Control (RRC)_INACTIVE state, Based on information identifying at least one MBS available to the UE, a second message is sent to the access network node containing a list of one or more MBS sessions that the UE can support when the UE is in the RRC_INACTIVE state, Methods that include... (Note 33) A method for User Equipment (UE) in the Radio Resource Control (RRC)_INACTIVE state, The access network node receives a paging message containing a list of at least one Temporary Mobile Group Identity (TMGI) associated with each available Multicast / Broadcast Service (MBS) session. Includes, The paging message is Each instruction associated with each TMGI in the list, and each instruction is, Whether the UE needs to transition to the RRC_CONNECTED state to receive the associated MBS session, or Whether the UE can remain in the RRC_INACTIVE state in order to receive the associated MBS session. Each instruction, or Instructions to configure a UE (Unified Element) so that it does not transition to the RRC_CONNECTED state in response to receiving a paging message, if the UE is a Release 18 or later UE. including, method. (Note 34) A method for User Equipment (UE), Receiving a multicast / broadcast service (MBS) with a Temporary Mobile Group Identity (TMGI), This includes receiving parameters associated with the TMGI from the access network node, and the parameters indicate conditions that, if met, cause the UE to transition from the Radio Resource Control (RRC)_CONNECTED state to the RRC_INACTIVE state, or from the RRC_INACTIVE state to the RRC_CONNECTED state. The system transitions between the RRC_CONNECTED state and the RRC_INACTIVE state based on the parameters, Methods that include... (Note 35) A method for User Equipment (UE), When the UE is in the RRC_INACTIVE state, the MBS Radio Bearer (MRB) receives multicast / broadcast services (MBS) from the access network node, The system transitions to the RRC_CONNECTED state when the MRB signal intensity falls below a threshold, Send a notification to the access network node requesting improved reliability of the MBS service, Methods that include... (Note 36) A method for User Equipment (UE), When User Equipment (UE) is in the RRC_INACTIVE state, the UE receives instructions from the distributed unit of the access network node for one or more multicast / broadcast service (MBS) sessions that the UE can access. Methods that include... (Note 37) A method for User Equipment (UE), Receiving information from the first access network node that includes a list of ongoing multicast / broadcast service (MBS) sessions of a second access network node adjacent to the first access network node, or a list of adjacent cells / frequency of at least one adjacent access network node having at least one ongoing MBS session. Methods that include... (Note 38) Access network node, A means for sending a first message to a User Equipment (UE) that includes an inquiry about the UE's ability to receive Multicast / Broadcast Service (MBS) when the User Equipment (UE) is in the Radio Resource Control (RRC)_INACTIVE state, A means for receiving a second message from the UE containing a list of one or more MBS sessions that the UE can support when the UE is in the RRC_INACTIVE state, provided that the UE has information identifying at least one MBS available to the UE, An access network node equipped with this feature. (Note 39) Access network node, A means of sending a paging message to a user equipment (UE) in the Radio Resource Control (RRC)_INACTIVE state, containing a list of at least one temporary mobile group identity (TMGI) associated with each available multicast / broadcast service (MBS) session. Equipped with, The paging message is Each instruction associated with each TMGI in the list, and each instruction is, Whether the UE needs to transition to the RRC_CONNECTED state to receive the respective MBS session associated with each TMGI, or Whether the UE can remain in the RRC_INACTIVE state in order to receive the respective MBS sessions associated with each TMGI. Each instruction, or Instructions to configure a UE (Unified Element) so that it does not transition to the RRC_CONNECTED state in response to receiving a paging message, if the UE is a Release 18 or later UE. including, Access network node. (Note 40) Access network node, The system includes a multicast / broadcast service (MBS) with a temporary mobile group identity (TMGI) for transmitting parameters associated with the TMGI to the user equipment (UE), where the parameters indicate conditions that, if met, cause the UE to transition from the Radio Resource Control (RRC)_CONNECTED state to the RRC_INACTIVE state, or from the RRC_INACTIVE state to the RRC_CONNECTED state. Access network node. (Note 41) Access network node, A means of providing multicast / broadcast services (MBS) to user equipment (UE) using an MBS radio bearer (MRB), A means of receiving notifications from the UE requesting improved reliability of the MBS service, Means for provisioning improved reliability and An access network node equipped with this feature. (Note 42) An access network node having a central unit and distributed units, The central unit is A means for receiving instructions from a core network node for at least one multicast / broadcast service (MBS) session that a User Equipment (UE) can access when the UE is in the Radio Resource Control (RRC)_INACTIVE state, A means for transmitting instructions to distributed units, Means for receiving responses from distributed units and Equipped with, Distributed units, Means for sending instructions to the UE Equipped with, Access network node. (Note 43) It is a core network node, A means of sending a message to an access network node containing instructions for one or more multicast / broadcast service (MBS) sessions that a User Equipment (UE) can access when the UE is in the Radio Resource Control (RRC)_INACTIVE state. A core network node equipped with these features. (Note 44) The first access network node, A means for transmitting information to User Equipment (UE) served by a first access network node, including a list of ongoing multicast / broadcast service (MBS) sessions of a second access network node adjacent to a first access network node, or a list of adjacent cells / frequency of at least one adjacent access network node having at least one ongoing MBS session. A first access network node equipped with [the following]. (Note 45) A source access network node for handing over User Equipment (UE) to a target access network node, wherein the source access network node is A means for sending a conditional handover request message containing MBS configuration information for the UE to the target access network node. A source access network node equipped with the following features. (Note 46) A target access network node for user equipment (UE) handover from a source access network node, wherein the target access network node is A means for receiving a conditional handover request message containing MBS configuration information for the UE from a source access network node, If there are no ongoing MBS sessions on the target access network node, establish an MBS session with the core network. Target access network nodes, including those mentioned above. (Note 47) User Equipment (UE), A means for receiving a first message from an access network node that includes an inquiry about the UE's ability to receive Multicast / Broadcast Service (MBS) when the UE is in the Radio Resource Control (RRC)_INACTIVE state, A means for sending a second message to an access network node, which includes a list of one or more MBS sessions that the UE can support when the UE is in the RRC_INACTIVE state, based on information that identifies at least one MBS available to the UE. User equipment equipped with these features. (Note 48) User Equipment (UE) is, A means for receiving a paging message from an access network node containing a list of at least one Temporary Mobile Group Identity (TMGI) associated with each available Multicast / Broadcast Service (MBS) session when the UE is in a Radio Resource Control (RRC) INACTIVE state. Equipped with, The paging message is Each instruction associated with each TMGI in the list, and each instruction is, Whether the UE needs to transition to the RRC_CONNECTED state to receive the associated MBS session, or Whether the UE can remain in the RRC_INACTIVE state in order to receive the associated MBS session. Each instruction, or Instructions to configure a UE (Unified Element) so that it does not transition to the RRC_CONNECTED state in response to receiving a paging message, if the UE is a Release 18 or later UE. including, User equipment. (Note 49) User Equipment (UE), A means for receiving a multicast / broadcast service (MBS) that has a temporary mobile group identity (TMGI), The system includes means for receiving parameters associated with TMGI from an access network node, wherein the parameters indicate conditions that, if met, cause the UE to transition from the Radio Resource Control (RRC)_CONNECTED state to the RRC_INACTIVE state, or from the RRC_INACTIVE state to the RRC_CONNECTED state. A means for transitioning between the RRC_CONNECTED state and the RRC_INACTIVE state based on parameters. User equipment equipped with these features. (Note 50) User Equipment (UE), When the UE is in the RRC_INACTIVE state, a means for receiving multicast / broadcast service (MBS) from an access network node via an MBS radio bearer (MRB), A means for transitioning to the RRC_CONNECTED state when the MRB signal strength falls below a threshold, A means of sending a notification to an access network node requesting improved reliability of the MBS service. User equipment equipped with these features. (Note 51) User Equipment (UE), A means of receiving instructions from a distributed unit of an access network node for one or more multicast / broadcast service (MBS) sessions that the UE can access when it is in the RRC_INACTIVE state. User equipment equipped with these features. (Note 52) User Equipment (UE), Means for receiving from a first access network node information including a list of ongoing multicast / broadcast service (MBS) sessions of a second access network node adjacent to the first access network node, or a list of adjacent cells / frequency of at least one adjacent access network node having at least one ongoing MBS session. User equipment equipped with these features. [Explanation of symbols]

[0130] 1. Telecommunications networks, telecommunications systems 3 UE 5 NG-RAN, base station 7 Core Network 8-1 AMF 8-2 SMF 8-3 UPF 8-4 MB-SMF 8-5 MB-UPF 8-6 MBSF 8-7 MBSTF 8-8 NEF 8-9 AF 8-10 PCF 8-11 NRF 8-12 UDM 8-13 AUSF 8-14 DN

Claims

1. Radio Resource Control (RRC) - to User Equipment (UE) in INACTIVE state, Temporary Mobile Group Identity (TMGI) and Information indicating whether the UE can receive multicast / broadcast services (MBS) corresponding to one or more MBS sessions associated with the TMGI while remaining in the RRC_INACTIVE state, A means for sending a paging message that includes at least one combination of the following: Means for transmitting to the UE information indicating at least one reference signal reception power threshold and / or at least one reference signal reception quality threshold for determining whether the UE transitions from the RRC_CONNECTED state to the RRC_INACTIVE state, or from the RRC_INACTIVE state to the RRC_CONNECTED state, Equipped with, While the UE is in the RRC_INACTIVE state, at least one MBS corresponding to one or more MBS sessions is provided to the UE. Access network node.

2. User Equipment (UE) in the Radio Resource Control (RRC) INACTIVE state, From the access network node, Temporary Mobile Group Identity (TMGI) and Information indicating whether the UE can receive multicast / broadcast services (MBS) corresponding to one or more MBS sessions associated with the TMGI while remaining in the RRC_INACTIVE state, A means for receiving a paging message containing at least one combination of, Means for receiving at least one MBS corresponding to one or more MBS sessions while the UE is in the RRC_INACTIVE state, Means for receiving from the access network node information indicating at least one reference signal reception power threshold and / or at least one reference signal reception quality threshold for determining whether the UE transitions from the RRC_CONNECTED state to the RRC_INACTIVE state, or from the RRC_INACTIVE state to the RRC_CONNECTED state, UE, equipped with [unclear / etc.].

3. Means for receiving a system information block from the access network node, The system includes means for transmitting information indicating an MBS service of interest to the UE based on the reception of the aforementioned system information block. The UE according to claim 2.

4. A means for receiving a system information block from the access network node for scheduling a multicast channel (MCCH) for the UE operating in the RRC_INACTIVE state, The system includes means for receiving the MCCH based on the system information block, The UE according to claim 2, wherein the MCCH includes information indicating an adjacent cell providing at least one MBS service.

5. The UE according to claim 2, wherein the information indicating the at least one reference signal received power threshold and / or at least one reference signal received quality threshold is included in the Multicast Channel (MCCH).

6. Radio Resource Control (RRC) - to User Equipment (UE) in INACTIVE state, Temporary Mobile Group Identity (TMGI) and Information indicating whether the UE can receive multicast / broadcast services (MBS) corresponding to one or more MBS sessions associated with the TMGI while remaining in the RRC_INACTIVE state, Sending a paging message that includes at least one combination of the following: The UE transmits to the UE information indicating at least one reference signal reception power threshold and / or at least one reference signal reception quality threshold for determining whether to transition from the RRC_CONNECTED state to the RRC_INACTIVE state, or from the RRC_INACTIVE state to the RRC_CONNECTED state. Includes, While the UE is in the RRC_INACTIVE state, at least one MBS corresponding to one or more MBS sessions is provided to the UE. Access network node method.

7. Radio Resource Control (RRC) method for User Equipment (UE) in an INACTIVE state, From the access network node, Temporary Mobile Group Identity (TMGI) and Information indicating whether the UE can receive multicast / broadcast services (MBS) corresponding to one or more MBS sessions associated with the TMGI while remaining in the RRC_INACTIVE state, Receiving a paging message containing at least one combination of the following: While the UE is in the RRC_INACTIVE state, it receives at least one MBS corresponding to one or more MBS sessions, The UE receives information from the access network node indicating at least one reference signal reception power threshold and / or at least one reference signal reception quality threshold for determining whether to transition from the RRC_CONNECTED state to the RRC_INACTIVE state, or from the RRC_INACTIVE state to the RRC_CONNECTED state, Methods that include...

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