Method and apparatus for enabling MBS multicast service continuity during UE mobility in RRC state

Abstract

The invention discloses a method for realizing MBS (Multimedia Broadcast Service) continuity during UE (User Equipment) movement in a communication network system in an RRC (Radio Resource Control) inactive state, which comprises the following steps of: configuring an RAN-based notification area (RNA) configuration for UE (User Equipment) through an RRC signaling by an existing service radio access network (RAN) node, and the configuration comprises the RNA configuration aiming at multicast or unicast service or the multicast or unicast service and the RNA configuration aiming at the multicast or unicast service. When the UE moves out of the configured multicast and / or unicast RNA area, the UE requests to indicate its mobility mode and / or to indicate that the RAN node should update RNA and / or receive the configured service by RRC signaling, so that the RAN node can update the RNA and / or service reception configuration for the UE and take into account the newly updated RNA area and / or service reception configuration when the UE moves to a new cell.

Description

Technical Field

[0001] The present application relates to the field of wireless communication systems, and more specifically to a method and apparatus for providing a radio access network (RAN) notification mechanism for multicast / broadcast service (MBS) multicast service continuity during the movement of user equipment (UE) in an inactive radio resource control (RRC) state. Background Art

[0002] New radio (NR) MBS is expected to cover a variety of applications and services, including public safety, mission-critical, vehicle-to-everything (V2X), IPv4 / IPv6 multicast transparent transmission, IPTV, wireless software transmission, group communication, and IoT applications in the 5G era. At the 3GPP RAN 88-e meeting (June 29-July 3, 2020), a new working item (WID) was approved to support MBS functions in the Release 17 5G specification. For Release 17 NR MBS, two transmission modes have been defined. The broadcast transmission mode focuses on meeting lower UE quality of service (QoS) requirements, and the target users include devices in RRC connected, RRC inactive, and RRC idle states. The multicast transmission mode can meet higher UE QoS requirements, and the target users are devices in the RRC connected state. At the RAN 94-e meeting (December 6-17, 2021), the discussion on the R18 NR MBS work item pointed out that multicast reception in the RRC connected state has low power consumption efficiency and may not fully meet the needs of MBS mission-critical services, especially when the number of UEs in the cell exceeds the cell access capacity according to the requirements of SA1 TR 23.774. Therefore, it is recommended to support UE multicast reception in the RRC inactive state and study the following objectives: standardize the function of supporting UE to receive multicast in the RRC inactive state [RAN2, RAN3]; study the point-to-multipoint (PTM) configuration for receiving multicast in the RRC inactive state [RAN2]; study the impact of UE mobility and state transition when receiving multicast in the RRC inactive state (seamless / lossless mobility is not required) [RAN2, RAN3].

[0003] According to SA1 TR 23.774, for MBS mission-critical scenarios where the number of users in a cell exceeds the normal access control limit, the UE, radio access network (RAN) node and core network (CN) are required to be able to quickly and temporarily reconnect the UE (i.e. triggered by user request or inter-cell mobility) to ensure service continuity of MBS multicast radio bearers in different RRC operating states (such as connected, inactive and idle states). However, according to the R17 MBS specification, only multicast reception in RRC connected mode is defined. Therefore, when the UE moves while receiving multicast services in RRC inactive state, the UE needs to first move to RRC connected state through the network (RAN node), and then the RAN node performs a handover operation on the UE to ensure service continuity of the multicast bearer. However, this mobility option that only relies on moving the UE to RRC connected state may not be the best choice for R18 NR MBS multicast services, especially for mission-critical services, which require fast / instant reconnection time according to TR 23.774 to avoid service interruption. Summary of the invention

[0004] The purpose of the present application is to propose a method and an apparatus for achieving continuity of multicast / broadcast service (MBS) multicast service during the movement of user equipment (UE) in an inactive radio resource control (RRC) state.

[0005] In a first aspect of the present application, a method for realizing multicast / broadcast service (MBS) multicast service continuity during the movement of a user equipment (UE) in an inactive radio resource control (RRC) state comprises: A RAN (Mobile RAN) node configures a RAN-based notification area configuration including a multicast RAN notification area and / or a unicast RAN notification area for a UE through RRC initial signaling; when the UE moves or performs a reselection procedure and reselects a cell belonging to the configured multicast RAN notification area and / or unicast RAN notification area, the UE continues to receive multicast and / or unicast services normally according to an existing reception configuration provided by an existing serving RAN node; when the UE moves or reselects a cell that does not belong to the configured multicast RAN notification area and / or unicast RAN notification area, the UE triggers an RRC signaling request to the existing serving RAN node, indicating whether to restore an RRC connection for the multicast and / or unicast service reception; the UE receives an RRC signaling response generated based on a UE indication from the existing serving RAN node or the new serving RAN node, the UE indication carrying a multicast and / or unicast RAN notification area (RAN notification area). area, RNA) update and / or multicast and / or unicast reception configuration; and the UE applies the multicast and / or unicast reception configuration to receive multicast and / or unicast service data according to the UE request, and considers the updated RNA configuration when moving or reselecting to a new cell.

[0006] In a second aspect of the present application, a communication network system includes a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor is configured to execute the above method.

[0007] In a third aspect of the present application, a non-transitory machine-readable storage medium stores instructions thereon, and when a computer executes the instructions, the instructions cause the computer to execute the above method.

[0008] In a fourth aspect of the present application, a chip includes a processor configured to call and run a computer program stored in a memory so that a device equipped with the chip executes the above method.

[0009] In a fifth aspect of the present application, a computer-readable storage medium stores a computer program, wherein the computer program enables a computer to execute the above method.

[0010] In a sixth aspect of the present application, a computer program product comprises a computer program, wherein the computer program enables a computer to execute the above method.

[0011] In a seventh aspect of the present application, a computer program is provided, wherein the computer program enables a computer to execute the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or related technologies, the following briefly introduces the drawings to be described in the embodiments. Obviously, the drawings are only some embodiments of the present application, and ordinary technicians in this field can obtain other drawings based on these drawings without paying any price.

[0013] Figure 1 is a schematic diagram showing an example of possible mobility modes in which an NR UE is in an inactive state during multicast service reception according to an embodiment of the present application.

[0014] Figure 2 It is a block diagram showing communication between one or more user equipment (UE) and a base station (such as a gNB) in a communication network system according to an embodiment of the present application.

[0015] Figure 3 It is a flowchart showing a method for achieving multicast / broadcast service (MBS) multicast service continuity during movement of a user equipment (UE) in an inactive radio resource control (RRC) state, which is performed by a communication network system according to an embodiment of the present application.

[0016] Figure 4 An example of UE RRC signaling request message information elements according to an embodiment of the present application is shown.

[0017] Figure 5 Detailed description is given of an example of a RAN node RRC signaling response information element carrying a multicast RAN Notification Area (RNA) configuration according to an embodiment of the present application.

[0018] Figure 6 FIG. 4 is an example showing a multicast RNA configuration provided in an RRC signaling response according to an embodiment of the present application.

[0019] Figure 7 The present invention illustrates an example of RRC inactive state movement of a UE between two cells under the same gNB during multicast service reception according to an embodiment of the present application.

[0020] Figure 8 The present invention illustrates an example of processing inactive state mobility between two cells under the same gNB during multicast service reception according to an embodiment of the present application.

[0021] Fig. 9 The present invention illustrates an example of RRC inactive state movement of a UE between two cells under different gNBs during multicast service reception according to an embodiment of the present application.

[0022] Fig.10 The present invention illustrates an example of processing movement between two cells under different gNBs during multicast service reception according to an embodiment of the present application.

[0023] Fig.11 is a block diagram of a system for wireless communication according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] The technical content, structural features, objectives and effects of the present application are described in detail below in conjunction with the accompanying drawings. Specifically, the terms in the embodiments of the present application are only used to describe the purpose of specific embodiments, and are not intended to limit the present application.

[0025] In Rel-17 NR, the UE mobility is handled differently in different RRC states. The characteristics of UE mobility in different RRC states in NR are summarized in Table 1. According to Table 1, in the RRC connected state, the UE context (i.e., the parameters required for communication between the UE and the network) has been established in the UE and the network, and the RAN node or cell to which the UE belongs can be known through a temporary identifier (i.e., C-RNTI, which is used to identify the UE in the RAN node). In the RRC connected state, the UE mobility is based on cell-level information, that is, the UE provides the measurement information of neighboring cells to the RAN node, and the RAN node instructs the UE to perform a handover operation based on this. In the RRC idle state, there is no UE context in the RAN and the UE is not registered to a specific cell. In the RRC idle state, the mobility is based on the tracking area management provided by the core network (CN), and the UE manages mobility when moving out of the provided tracking area through the cell selection and reselection process. In the RRC inactive state, the UE context is saved in the UE and the RAN node (e.g., gNB), and the user plane connection (i.e., N3 interface) and the control connection between the RAN node and the CN (i.e., N2 interface) are retained only for the UE, but the RAN node releases the RRC connection with the UE.

[0026] Table 1: Mobility processing methods in different 5G RRC states

[0027]

[0028] Based on the above discussion, possible processing options for ensuring service continuity for UEs receiving MBS multicast in RRC inactive state are as follows. A common possible solution option is to reuse the concept of Rel-17 core network (CN) tracking area (i.e., tracking the mobility of the UE based on the configured MBS service area), which is also used for the mobility of MBS broadcast. However, this option may not meet the goal of quickly reconnecting the UE for multicast reception (as required by TR 23.774) because it relies on the interaction between the UE and the core network. Another possible solution option is to adopt a RAN notification area (RNA) based solution (i.e., tracking the mobility of the UE by updating the reconfigurable RAN notification area), which is used for the mobility of NR unicast inactive state. This option can meet the service continuity requirements of multicast and achieve the fast reconnection goal required by TR 23.774 because it relies on the interaction between the UE and the RAN node. Reusing this inactive state mobility solution for MBS multicast may require the following enhancements to the existing NR unicast solution: 1) Since in NR MBS, multicast service reception is cell-based, when considering reusing the existing unicast RNA-based inactive state mobility solution for MBS multicast, it is unclear how the existing mechanisms can ensure inactive state mobility service continuity when the UE moves from one cell to a new cell when receiving only multicast services, only unicast services, or both multicast and unicast services. 2) Assuming that the UE's mobility during inactive state multicast and / or unicast reception may be from one cell to another within the same RAN node (e.g., intra-gNB mobility) or from one cell to another within different RAN nodes (e.g., inter-gNB mobility), it is unclear how the existing unicast RNA-based solution handles such situations. Figure 1 The specific mobility mode shown. The following embodiments of the present application discuss a set of methods and enhancements to solve these problems.

[0029] In order to solve the above problems, some embodiments of the present application provide a set of methods and signaling enhancements, including introducing the concept of a service-based and scenario-specific RAN notification area mobility mechanism, and defining related UE and RAN node signaling enhancements to ensure the continuity of multicast and / or unicast services when the UE moves in an inactive state, and allow time-sensitive multicast services to reconnect quickly according to the requirements of TR 23.774. In these example methods, the UE configures a RAN notification area through a serving RAN node (e.g., a gNB or gNB-CU node) through an RRC signaling message (e.g., an RRC release message with a suspended configuration), including a multicast RAN notification area (RNA) or a unicast RAN notification area, or a combination of multicast and unicast RAN notification areas. When the UE moves to a new cell, the UE evaluates whether the cell belongs to one of the configured multicast or unicast RAN notification areas. If the cell belongs to at least one RAN notification area, the UE continues MBS multicast and / or unicast reception normally in the new cell based on the existing reception configuration provided by the gNB node. If the cell does not belong to any configured RAN notification area, the UE shall initiate / trigger an RRC signaling request to the gNB, wherein the RRC signaling request includes an inactive-radio network temporary identifier (I-RNTI) value of the same or different RAN node, a restoration cause indicating an update of the RAN notification area, and / or an indication of whether the connection is restored for multicast services, unicast services, or both. Based on the RRC signaling request provided by the UE, the gNB node configures an RRC signaling response carrying a reception configuration for multicast or unicast or both as indicated by the UE, and an updated RNA area configuration based on the UE's intra-gNB mobility mode determined by the gNB according to some embodiments or the UE's inter-gNB mobility mode determined by other embodiments. The gNB then transmits the configured RRC response signaling to the UE, followed by the transmission of unicast and / or multicast service data to the UE. Upon receiving the RRC response message, the UE applies the multicast and / or unicast reception configuration to receive the multicast and / or unicast service data as requested by the UE and considers the updated RNA configuration when moving or performing cell reselection. According to the above process, the UE can continue to receive multicast and unicast services when moving between different cells based on interaction only with the RAN node, regardless of the deployment scenario (e.g., intra-gNB mobility or mobility between different gNBs).

[0030] Figure 2One or more user equipment (UE) 10, a first RAN node (e.g., gNB or gNB-DU) 20, and a second RAN node (e.g., gNB or gNB-DU) 30 provided in a communication network system 40 according to one embodiment of the present application are described. The communication network system 40 includes one or more UEs 10, a first base station 20, and a second RAN node 30. The one or more UEs 10 may include a memory 12, a transceiver 13, and a processor 11 coupled to the memory 12 and the transceiver 13. The first RAN node 20 may include a memory 22, a transceiver 23, and a processor 21 coupled to the memory 22 and the transceiver 23. The second base station 30 may include a memory 32, a transceiver 33, and a processor 31 coupled to the memory 32 and the transceiver 33. The processor 11, 21, or 31 may be configured to implement the functions, procedures, and / or methods proposed in this description. Each layer of the radio interface protocol may be implemented in the processor 11, 21, or 31. The memory 12, 22 or 32 is operatively coupled to the processor 11, 21 or 31 and stores various information to operate the processor 11, 21 or 31. The transceiver 13, 23 or 33 is operatively coupled to the processor 11, 21 or 31 and is used to transmit and / or receive wireless signals.

[0031] The processor 11, 21 or 31 may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits and / or data processing devices. The memory 12, 22 or 32 may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium and / or other storage devices. The transceiver 13, 23 or 33 may include a baseband circuit for processing radio frequency signals. When these embodiments are implemented in software, the techniques described herein may implement these functions through modules (e.g., programs, functions, etc.). These modules may be stored in the memory 12, 22 or 32 and executed by the processor 11, 21 or 31. The memory 12, 22 or 32 may be implemented inside the processor 11, 21 or 31, or may be implemented outside the processor 11, 21 or 31, and may be coupled to the processor 11, 21 or 31 through various known communication methods.

[0032] In some embodiments, the communication network system 40 is configured to perform the following method to achieve continuity of multicast / broadcast service (MBS) multicast service during the mobility of user equipment (UE) in a radio resource control (RRC) inactive state. The method comprises: the UE is configured as a RAN-based notification area configuration including a multicast RAN notification area and / or a unicast RAN notification area through an existing serving radio access network (RAN) node through RRC initial signaling; when the UE moves or performs a reselection procedure and reselects to a cell belonging to the configured multicast RAN notification area and / or the configured unicast RAN notification area, the UE continues to normally receive MBS multicast and / or unicast on the cell based on the existing reception configuration provided by the existing serving RAN node; when the UE moves or reselects to a cell that does not belong to the configured multicast RAN notification area and / or the configured unicast RAN notification area, the UE triggers an RRC signaling request to the existing serving RAN node, indicating whether to restore the RRC connection for MBS multicast and / or unicast reception; the UE receives an RRC signaling response generated based on the UE indication from the existing serving RAN node or the new serving RAN node, the response carrying the multicast and / or unicast RAN notification area (RAN notification area). area, RNA) update and / or multicast and / or unicast reception configuration; the UE applies the multicast and / or unicast reception configuration to receive the multicast and / or unicast service data indicated by the UE request, and considers the updated RNA configuration when moving or performing cell reselection to a new cell.

[0033] In some embodiments, the existing serving RAN node and / or the new serving RAN node may be a gNB node, a gNB-central unit (gNB-CU) or a gNB-distributed unit (gNB-DU). In some embodiments, the RRC initial signaling is an RRC release or RRC reconfiguration message carrying a multicast and / or unicast RAN notification area (RAN notification area, RNA) configuration and / or a multicast and / or unicast service reception configuration. In some embodiments, the RRC signaling request is an RRC recovery request or RRC recovery request 1 message including a radio network temporary identifier (RNTI) value, a recovery reason indicating an RNA update and / or an indication of whether to restore the RRC connection for multicast service reception and / or unicast service reception. In some embodiments, the indication indicating whether to restore the RRC connection for multicast service and / or unicast service is included in a spare bit field of the RRC recovery request or RRC recovery request 1 message.

[0034] In some embodiments, the RRC signaling response is an RRC release message or an RRC reconfiguration message carrying a multicast and / or unicast RAN notification area (RAN notification area, RNA) update and / or a multicast and / or unicast service reception configuration. In some embodiments, both the RRC initial signaling and the RRC signaling response are RRC reconfiguration or RRC release with suspension messages containing a multicast RAN notification area and / or a unicast RAN notification area. In some embodiments, the multicast RAN notification area is configured as: a cell list, where the UE is provided with an explicit list of one or more cells constituting the multicast RAN notification area; and / or a RAN area list, where the UE is provided with at least one RAN area ID, the RAN area being a subset of a core network (CN) tracking area, equal to a CN tracking area, or a set of cells under a gNB distribution unit (DU). In some embodiments, the RAN area is specified by a RAN area ID, which includes a tracking area code (TAC) and / or a RAN area code.

[0035] In some embodiments, the indication of whether the RRC connection is a multicast service and / or unicast service recovery is as follows: a spare bit value of zero indicates that the RRC is a unicast recovery, a spare bit value of one indicates that the RRC is a unicast recovery, and if the field does not exist, the field indicates that the RRC is both unicast and multicast recovery.

[0036] In some embodiments, the RRC signaling request triggered by the UE to the existing serving RAN node may include a resumption cause indicating an RNA region update, an indication indicating whether the RRC connection is for multicast and / or unicast service resumption, and / or an RNTI value of the same or different RAN node.

[0037] In some embodiments, if an existing RAN node receives an RRC signaling request from a UE and includes an RNTI value of the same RAN node, the existing RAN node assumes that the UE's movement is an intra-gNB movement from a previous serving gNB distribution unit (gNB-DU) to a new gNB-DU. In some embodiments, the previous gNB-DU encapsulates the RRC signaling request in a non-UE associated message (i.e., an Initial Uplink RRC Transfer message) and transmits the Initial Uplink RRC Transfer message to the existing gNB-CU. In some embodiments, based on the indication provided by the UE in the RRC signaling request, the gNB-CU sends a UE Context Setup Request message to the new gNB-DU to which the UE has moved to create a UE unicast context and / or a UE multicast context and to set up one or more multicast and / or data bearers. In some embodiments, the UE Context Setup Request message includes a request for the new gNB-DU to include unit group configuration information of the target cell in the UE Context Setup Response message. In some embodiments, the new gNB-DU responds to the existing gNB-CU with a UE Context Setup Response message, which includes the UE unicast and / or multicast context, multicast and / or data bearer configuration, and updated unit group information including the target cell identifier requested by the previous gNB-CU. In some embodiments, the gNB-CU generates an RRC Reconfiguration or Release message, which includes the updated unicast / multicast RNA region and the multicast and / or unicast reception configuration based on the updated unit group information; then, encapsulates the RRC Reconfiguration or Release message in an RRC Downlink Transfer message and sends the RRC Downlink Transfer message to the new gNB-DU. In some embodiments, the new gNB-DU forwards the RRC Response message to the UE and further forwards the multicast and / or unicast service data to the UE based on the content indicated in the UE request.

[0038] In some embodiments, if the existing serving RAN node receives an RRC signaling request containing the RNTI of another serving RAN node, the serving RAN node assumes that the UE's movement is an inter-gNB movement from the existing gNB node to the new gNB node. In some embodiments, the new gNB sends a context retrieval request to the existing RAN node to retrieve the UE unicast context (if the recovery value indicated in the UE RRC signaling request is zero), or to retrieve the UE multicast context (if the spare bit value in the UE RRC signaling request is zero), or if no spare bit indication is provided, to retrieve the UE's multicast and unicast contexts. In some embodiments, if the new gNB successfully retrieves the UE unicast and / or multicast context, the new gNB uses the UE's unicast and / or multicast context; otherwise, the new gNB establishes a new UE unicast and / or multicast context. In some embodiments, the new gNB responds to the UE with an RRC connection release message to keep the UE in the RRC inactive state, or sends an RRC connection recovery message to change the UE state to the RRC connected state by viewing the RRC response signaling carrying the multicast and / or unicast service reception configuration and the updated RNA region configuration according to the retrieved or newly established UE unicast and / or multicast context. In some embodiments, the new gNB further contacts the service access and mobility management function (AMF) to switch the N2 and N3 tunnels to the new gNB, and the new gNB further transmits the multicast and / or unicast service data to the UE according to the content indicated in the UE request. In some embodiments, after receiving the RRC signaling response from the existing serving RAN node or the new serving RAN node, the UE applies the multicast and / or unicast reception configuration to receive the multicast and / or unicast service data, and considers the updated RNA configuration when moving or reselecting to a new cell.

[0039] Figure 3 It is a flow chart illustrating a method for achieving multicast / broadcast service (MBS) multicast service continuity when a user equipment (UE) moves in an inactive radio resource control (RRC) state in a wireless communication network system according to an embodiment of the present application. Figure 3Description, in some embodiments, the method includes the following steps: configuring a RAN-based notification area configuration including a multicast RAN notification area and / or a unicast RAN notification area for a UE through an existing serving radio access network (RAN) node through RRC initial signaling; when the UE moves or performs a reselection procedure and reselects a cell belonging to the configured multicast RAN notification area and / or unicast RAN notification area, the UE continues to perform MBS multicast and / or unicast reception on the cell normally according to the existing reception configuration provided by the existing serving RAN node; when the UE moves or reselects to a cell that does not belong to the configured multicast RAN notification area and / or unicast RAN notification area, the UE triggers an RRC signaling request to the existing serving RAN node, indicating whether to restore the RRC connection for MBS multicast and / or unicast reception; the UE receives an RRC signaling response generated according to the UE instruction from the existing serving RAN node or the new serving RAN node, the signaling response including the multicast and / or unicast RAN notification area (RANnotification area). The UE then applies the multicast and / or unicast reception configuration to receive the multicast and / or unicast service data indicated in the UE request, and considers the updated RNA configuration when moving or performing reselection to a new cell.

[0040] In the above exemplary method group, the RRC signaling request of the UE is an RRC recovery request or an RRC recovery request 1, which includes an inactive radio network temporary identifier (I-RNTI) value, a recovery reason indicating an RNA update, and / or an indication indicating whether the connection is recovered for multicast service, unicast service, or both. In the above exemplary method group, the indication of whether the connection is recovered for multicast service, unicast service, or both is provided in a spare bit field of the RRC recovery request or the RRC recovery request 1.

[0041] Figure 4 An example of a UE signaling request message contained in a paging information element according to an embodiment of the present application is shown. Figure 5 An example of information elements of a multicast RNA configuration signaling message according to an embodiment of the present application is shown. Figure 4 and Figure 5 It is explained that, in the above exemplary method group, the RRC signaling message is an RRC connection release message and a suspension configuration including a multicast RAN notification area, a unicast RAN notification area or a combination of the two.

[0042] In the above exemplary method group, the multicast RAN notification area can be configured as: 1. A cell list, where the UE is provided with a clear list of cells (one or more) that constitute the RAN notification area. 2. A RAN area list, where the UE is provided with (at least one) RAN area ID, where the RAN area is a subset of the core network (CN) tracking area, equal to a CN tracking area, or a group of cells under a gNB-DU. The RAN area is specified by a RAN area ID, including a TAC (Tracking Area Code) and an optional RAN area code, such as Figure 6 shown.

[0043] In the above exemplary method group, the UE indicates to the gNB whether the connection is restored for multicast service, unicast service or both types of services as follows: a spare bit value of zero indicates that the RRC is restored for unicast, a spare bit value of one indicates that the RRC is restored for multicast, and if the field is missing, it indicates that the RRC is restored for unicast and multicast, as shown in Table 2.

[0044] In the above exemplary method group, the operation of the RAN node on the received RRC signaling request containing the UE-indicated spare bit can be: if the spare bit value is zero, configure the RRC release or reconfiguration message to perform unicast reception configuration and / or unicast RNA area update; if the spare bit value is one, configure the RRC release or reconfiguration message to perform multicast reception configuration and / or multicast RNA area update; if the spare bit is not indicated, configure the RRC release or reconfiguration message to perform unicast and multicast reception configuration and unicast and multicast RNA updates at the same time, as shown in Table 2.

[0045] Table 2: Indications provided by the UE via spare bits in RRC signalling requests

[0046]

[0047] In the above example method group, if the RAN node (gNB) receives an RRC signaling request containing the RNTI of the same RAN node, the RAN node may assume that the mobility mode of the UE is intra-gNB mobility and may respond according to the following embodiments. In the above example method group, if the gNB receives an RRC signaling request containing the RNTI of other RAN nodes, the gNB may assume that the mobility mode of the UE is inter-gNB mobility and the other nodes may respond according to the following embodiments.

[0048] Mobility between two cells under the same gNB: Figure 7 An example of RRC inactive state mobility between two cells under the same gNB during multicast service reception of a UE according to an embodiment of the present application is shown. Figure 8An example of handling inactive state mobility between two cells under the same gNB during multicast service reception according to an embodiment of the present application is shown. Figure 7 and Figure 8 Note that in certain embodiments, according to the above example method group, if the RAN node (gNB) receives an RRC signaling request containing the RNTI of the same RAN node, the RAN node may assume that the mobility mode of the UE is intra-gNB mobility, such as Figure 7 as shown, and can be based on Figure 8 Make a response.

[0049] Figure 8 Description, in some embodiments, the UE triggers an RRC signaling request to the last gNB-DU, including the RNTI value of the same gNB, the resumption reason indicating an RNA update, and / or an indication indicating whether the RRC connection is resumed for multicast services, unicast services, or both groups of services. The last gNB-DU includes the RRC signaling request in a non-UE related (initial uplink RRC message transmission) message and transmits the RRC signaling request to the gNB-CU. Based on the indication provided in the RRC resume message, the gNB-CU sends a UE context setup request message to the new gNB-DU where the UE is present to create a UE unicast context and / or UE multicast context and to setup one or more multicast and / or data bearers. The UE context setup request includes a request for the new gNB-DU to include the cell group configuration information of the target cell where the UE is located. The new gNB-DU responds to the gNB-CU with a UE context setup response message, including the unicast context and / or UE multicast context, the multicast and / or data bearers, and the target cell ID, which was requested by the gNB-CU. The gNB-CU generates an RRC reconfiguration or release message, carrying the updated RNA area configuration and multicast and / or unicast reception configuration based on the new cell group, and encapsulates the RRC reconfiguration or release message in a downlink RRC message transmission to the new gNB-DU. The new gNB-DU forwards the RRC message to the UE and then forwards the multicast and / or unicast service data to the UE according to the content indicated in the UE request.

[0050] Mobility between two cells under different gNBs (or gNB-CUs):

[0051] Fig. 9 An example of RRC inactive state mobility between two cells under different gNBs during multicast service reception of a UE according to an embodiment of the present application is shown. Fig.10 An example of handling movement between two cells under different gNBs during multicast service reception according to an embodiment of the present application is shown. Fig. 9 and Fig.10Note that in some embodiments, according to the above example method group, if the RAN node (gNB) receives an RRC signaling request containing the RNTI of a different RAN node, the RAN node may assume that the mobility mode of the UE is inter-gNB mobility, such as Fig. 9 as shown, and can be based on Fig.10 Make a response.

[0052] Fig.10 Description: In certain embodiments, the UE triggers an RRC signaling request containing the RNTI value of the last gNB, the reason for resumption indicating an RNA update, and / or an indication indicating whether the RRC connection is resumed for multicast services, unicast services, or both sets of services, to the new gNB. The new gNB retrieves the contact information of the last serving gNB using the I-RNTI and sends a request to retrieve the UE's unicast context (if the spare bit value in the RRC resume request is zero), or to retrieve the UE's MBS multicast context (if the spare bit value in the RRC resume request is zero), or to retrieve both if the spare bit indication is not provided in the RRC resume request. If the new gNB successfully retrieves the context, it uses the context; otherwise, the new gNB establishes a new UE unicast and / or multicast context. The new gNB replies to the UE with an RRC Connection Release message (keeping the UE in the RRC Inactive state) or an RRC Connection Resume message (changing its state to the RRC Connected state), carrying the reception configuration for multicast, unicast, or both services as indicated by the UE, and the updated RNA region configuration according to the retrieved context or the newly established UE unicast and / or multicast context. The new gNB also contacts the serving AMF to switch the N2 and N3 tunnels to the new gNB. Subsequently, the new gNB transmits the multicast and / or unicast service data to the UE according to the content indicated in the UE request.

[0053] In summary, certain embodiments of the present application provide a method for handling the continuity of MBS multicast services during the movement of UE in an RRC inactive state based on RAN notification mechanism configuration. The main advantages of this new example method include: 1. The new example method introduces a RAN notification area concept mechanism for multicast, enabling the UE to quickly reconnect to the network to ensure the continuity of MBS multicast services, in line with the Rel-18 WID requirements for MBS mission-critical services. 2. The new example mechanism provides signaling enhancements, allowing the UE to move flexibly in an RRC inactive state, across different RAN deployment scenarios (such as intra-gNB mobility and inter-gNB mobility) during multicast and / or unicast reception, based solely on the interaction between the UE and the RAN node without relying on the core network (CN).

[0054] Fig.117 is a block diagram of an exemplary wireless communication system 700 according to an embodiment of the present application. The embodiments described herein may be implemented into a system using any appropriately configured hardware and / or software. Fig.11 A system 700 is shown, which includes a radio frequency (RF) circuit 710, a baseband circuit 720, an application circuit 730, a memory / storage device 740, a display 750, a camera 760, a sensor 770, and an input / output (I / O) interface 780, which are coupled to each other at least as shown. The application circuit 730 may include circuits, such as but not limited to one or more single-core or multi-core processors. The processor may include any combination of general-purpose processors and special-purpose processors, such as a graphics processor, an application processor. The processor may be coupled to a memory / storage device and configured to execute instructions stored in the memory / storage device to enable various applications and / or operating systems to run on the system.

[0055] While the present disclosure has been described in connection with what is considered to be the most practical and preferred embodiment, it is to be understood that the present disclosure is not limited to the disclosed embodiment, but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

1. A method for realizing MBS multicast service continuity during the movement of a user equipment UE in an RRC inactive state, characterized in that: include: RAN-based notification area configuration including a multicast RAN notification area and / or a unicast RAN notification area is configured for the UE via an existing serving radio access network RAN ​​node via RRC initial signaling; When the UE moves or performs a reselection procedure and reselects a cell belonging to the configured multicast RAN notification area and / or unicast RAN notification area, the UE continues to receive the multicast and / or unicast services normally according to the existing reception configuration provided by the existing serving RAN node; When the UE moves or reselects a cell that does not belong to the configured multicast RAN notification area and / or unicast RAN notification area, the UE triggers an RRC signaling request to the existing serving RAN node to indicate whether to receive a restoration RRC connection for the multicast and / or unicast service; The UE receives, from the existing serving RAN node or the new serving RAN node, an RRC signaling response generated based on a UE indication, the UE indication carrying a multicast and / or unicast RAN notification area RNA update and / or a multicast and / or unicast reception configuration; as well as The UE applies the multicast and / or unicast reception configuration to receive multicast and / or unicast service data according to the UE request, and considers the updated RNA configuration when moving or reselecting to a new cell.

2. The method according to claim 1, characterized in that: The existing serving RAN node and / or the new serving RAN node is a gNB node or a gNB central unit gNB-CU node.

3. The method according to claim 1, characterized in that The RRC initial signaling is an RRC release or RRC reconfiguration message carrying the multicast and / or unicast RAN notification area RNA configuration and / or multicast and / or unicast service reception configuration.

4. The method according to claim 1, characterized in that The RRC signaling request is an RRC recovery request or an RRC recovery request 1 message including a radio network temporary identifier RNTI value, a recovery cause indicating RNA update, and / or an indication of whether to recover the RRC connection for multicast service reception and / or unicast service reception.

5. The method according to claim 4, characterized in that An indication of whether to resume the RRC connection for the multicast service and / or the unicast service is provided in a spare bit field of the RRC resume request or the RRC resume request 1 message.

6. The method according to claim 1, characterized in that The RRC signaling response is an RRC release message or an RRC reconfiguration message carrying the multicast and / or unicast RAN notification area RNA update and / or multicast and / or unicast service reception configuration.

7. The method according to any one of claims 1 to 6, characterized in that The RRC initial signaling and the RRC signaling response are both RRC reconfiguration including the multicast RAN notification area and / or the unicast RAN notification area or RRC release with a suspend message.

8. The method according to claim 7, characterized in that The multicast RAN notification area is configured as follows: a cell list, wherein the UE is provided with an explicit list of one or more cells constituting a multicast RAN notification area; and / or A list of RAN areas, wherein the UE is provided with at least one RAN area ID, a RAN area being a subset of a core network CN tracking area or being equivalent to the CN tracking area or a group of cells managed by one gNB distribution unit DU.

9. The method according to claim 8, characterized in that The RAN area is specified by a RAN area ID, which includes a tracking area code TAC and / or a RAN area code.

10. The method according to any one of claims 1 to 9, characterized in that The indication of whether to restore the RRC connection for the multicast service and / or the unicast service is as follows: A spare bit with a value of 0 indicates RRC recovery of unicast, a spare bit with a value of 1 indicates RRC recovery of unicast, and if the field does not exist, it indicates that both unicast and multicast are recovered.

11. The method according to any one of claims 1 to 10, characterized in that If the existing RAN node receives an RRC signaling request from the UE and the RRC signaling request contains the RNTI value of the same RAN node, the existing RAN node assumes that the movement of the UE is an intra-gNB movement from the last serving gNB distributed unit gNB-DU to a new gNB-DU.

12. The method according to claim 11, characterized in that The UE triggers the RRC signaling request to the existing gNB-CU through the last gNB-DU, and the RRC signaling request includes the RNTI value of the same gNB, the restoration reason indicating the RNA area update and / or an indication of whether to receive the restored RRC connection for multicast and / or unicast services.

13. The method according to claim 12, characterized in that The last gNB-DU includes the RRC signaling request in a non-UE associated message, i.e., an initial uplink RRC transmission message, and transmits the initial uplink RRC transmission message to the existing gNB-CU.

14. The method according to claim 13, characterized in that The gNB-CU sends a UE context establishment request message to the new gNB-DU to which the UE moves based on the indication provided by the UE in the RRC signaling request to create a UE unicast context and / or a UE multicast context and set up one or more multicast and / or data bearers.

15. The method according to claim 14, characterized in that The UE Context Setup Request message includes a request for the new gNB-DU to include the group configuration information of the target cell in the UE Context Setup Response message.

16. The method according to claim 15, characterized in that The new gNB-DU responds to the existing gNB-CU with the UE context establishment response message, where the UE context establishment response message includes the UE unicast and / or the UE multicast context, as well as multicast and / or data bearer configuration and updated group configuration information including the target cell identifier.

17. The method according to claim 16, characterized in that The gNB-CU generates an RRC reconfiguration or release message, including an updated unicast / multicast RNA area based on the updated group configuration information, and a multicast and / or unicast reception configuration; then, encapsulates the RRC reconfiguration or the release message in an RRC downlink transmission message and sends it to the new gNB-DU.

18. The method according to claim 17, characterized in that The new gNB-DU forwards the RRC response message to the UE, and further forwards the multicast and / or unicast service data to the UE according to the content indicated in the UE request.

19. The method according to any one of claims 1 to 10, characterized in that If the serving RAN node receives an RRC signaling request containing the RNTI of other serving RAN nodes, the serving RAN node assumes that the movement of the UE is an inter-gNB movement from the existing gNB node to the new gNB node.

20. The method according to any one of claims 1 to 19, characterized in that The UE triggers the RRC signaling request to the new gNB node, wherein the RRC signaling request includes the RNTI value of the existing gNB node, a restoration reason indicating an RNA region update, and / or an indication of whether to receive a restored RRC connection for multicast and / or unicast services.

21. The method according to claim 20, characterized in that The new gNB sends a context retrieval request to the existing RAN node to retrieve the UE unicast context if the indication recovery value in the UE RRC signaling request is zero, or to retrieve the UE multicast context if the spare bit value in the UE RRC signaling request is zero, or if no spare bit indication is provided in the UE RRC signaling request, to retrieve both UE multicast and unicast contexts.

22. The method according to claim 21, characterized in that If the new gNB successfully retrieves the UE unicast and / or multicast context, the new gNB uses the UE unicast and / or multicast context; otherwise, the new gNB establishes a new UE unicast and / or multicast context.

23. The method according to claim 22, characterized in that The new gNB responds to the UE through the RRC connection release to keep the UE in the RRC inactive state, or changes the UE state to the RRC connected state through the RRC connection recovery message, according to the multicast and / or unicast service reception configuration carried in the RRC response signaling and the RNA area configuration updated according to the retrieved or newly established UE unicast and / or multicast context.

24. The method according to claim 23, characterized in that The new gNB further contacts the service access and mobility management function AMF to switch the N2 and N3 tunnels to the new gNB, and the new gNB further transmits the multicast and / or unicast service data to the UE according to the content indicated in the UE request.

25. The method according to any one of claims 1 to 24, characterized in that After receiving the RRC signaling response from the existing serving RAN node or the new serving RAN node, the UE applies the multicast and / or unicast reception configuration to receive the multicast and / or unicast service data, and considers the new updated RNA configuration when moving or reselecting to a new cell.

26. A communication network system, characterized in that: include: Memory; Transceiver; as well as a processor coupled to the memory and the transceiver; Wherein, the processor is configured to execute the method of any one of claims 1 to 25.

27. A non-transitory machine-readable storage medium, characterized in that Instructions are stored thereon, and when a computer executes the instructions, the instructions cause the computer to perform the method of any one of claims 1 to 25.

28. A chip, characterized in that: include: A processor configured to call and run a computer program stored in a memory so that a device equipped with the chip executes a method according to any one of claims 1 to 25.

29. A computer-readable storage medium, characterized in that: A computer program is stored therein, wherein the computer program causes a computer to execute the method of any one of claims 1 to 25.

30. A computer program product, characterized in that Comprising a computer program, wherein the computer program causes a computer to perform the method of any one of claims 1 to 25.

31. A computer program, characterized in that The computer program causes a computer to execute the method according to any one of claims 1 to 25.

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