CN118042420A

CN118042420A - Method and equipment for supporting multicast service transmission

Info

Publication number: CN118042420A
Application number: CN202211364734.9A
Authority: CN
Inventors: 王弘; 许丽香; 汪巍崴
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2022-11-02
Filing date: 2022-11-02
Publication date: 2024-05-14
Also published as: WO2024096502A1

Abstract

The invention provides a method and equipment for supporting multicast service transmission, wherein a method executed by a second node in a wireless communication system is disclosed, and the method comprises the following steps: receiving a first message from a first node, wherein the first message carries relevant information of the UE in an RRC inactive state; and processing based on the first message.

Description

Method and equipment for supporting multicast service transmission

Technical Field

The present application relates to wireless communication technology, and in particular, to an improved method and apparatus for multicast service transmission.

Background

In order to meet the increasing demand for wireless data communication services since the deployment of 4G communication systems, efforts have been made to develop improved 5G or quasi 5G communication systems. Therefore, a 5G or quasi 5G communication system is also referred to as a "super 4G network" or a "LTE-after-system".

Wireless communication is one of the most successful innovations in modern history. Recently, the number of subscribers to wireless communication services exceeds 50 billion and continues to grow rapidly. As smartphones and other mobile data devices (e.g., tablet computers, notebook computers, netbooks, e-book readers, and machine type devices) become increasingly popular among consumers and businesses, the demand for wireless data services is rapidly growing. To meet the high-speed growth of mobile data services and support new applications and deployments, it is important to improve the efficiency and coverage of the wireless interface.

Disclosure of Invention

Technical problem

In a mobile communication system, service data is provided to users in a broadcast and multicast manner. Such services are referred to as multimedia broadcast multicast services, hereinafter referred to as MBS (Multicast and Broadcast Service). When the MBS is a multicast service, only the UE in the RRC connected mode may receive data of the MBS service. However, the UE has a limited power, and in order to save power for the UE, the present invention provides an improved method and apparatus for multicast service transmission.

Solution scheme

According to an aspect of an embodiment of the present invention, there is provided a method performed by a second node in a wireless communication system, the method comprising: receiving a first message from a first node, wherein the first message carries relevant information of the UE in an RRC inactive state; and processing based on the first message.

According to an embodiment of the present invention, the information about the UE in the RRC inactive state includes one of:

An identification of the UE;

Number of UEs;

indication information of the UE having the RRC inactive state;

session identification of MBS added by UE;

status information of MBS;

Configuration information of MBS Radio Bearers (MRBs);

A regional scope;

whether the RRC inactive state UE is supported to receive the indication information of the MBS service;

indication information that the MBS context information and/or configuration information continues to be maintained.

According to an embodiment of the invention, the area coverage is a RAN paging coverage or a predetermined cell list.

According to an embodiment of the present invention, the second node and the first node belong to the same area range.

According to the embodiment of the invention, the UE indication information with the RRC inactive state indicates the UE with the RRC inactive state in the range of the first node or in the range of the area to which the first node belongs.

According to an embodiment of the present invention, the first message is a UE-specific message;

according to an embodiment of the invention, the first message is one of:

multicast dedicated messages for MBS;

public messages.

According to an embodiment of the invention, the processing comprises at least one of:

The second node maintains UE context information;

The second node keeps MBS context information;

the second node continues to transmit multicast data;

the second node does not release signaling resources and/or user plane resources of the multicast service;

the second node does not initiate a multicast context release request message or distribute a release command message to the first node.

According to the embodiment of the invention, the number of the UEs in the RRC inactive state is at least 1.

According to the embodiment of the invention, the UE in the RRC inactive state is in the first node or the area range to which the first node belongs.

According to an embodiment of the invention, if the second node is a base station, the processing further comprises at least one of:

Sending a request for establishing a user plane to a core network;

transmitting a third message to a third node, wherein the third message carries relevant information of the UE in an RRC inactive state;

And sending a second message to the first node, wherein the second message carries the relevant information of the UE in the RRC inactive state.

According to an embodiment of the present invention, the third message includes information about the UE in the RRC inactive state of the second node and/or information about the received UE in the RRC inactive state of the other node.

According to an embodiment of the invention, the number of received other nodes is at least 1.

According to an embodiment of the present invention, the second node receives a response message from the third node, where the response message carries information about UEs in an RRC inactive state of the third node.

According to the embodiment of the invention, the MRB configuration information carried in the response message is the same as the MRB configuration information carried in the third message.

According to an embodiment of the invention, the second node is a base station, a distribution unit DU or a concentration unit CU and the first node is a base station or a concentration unit CU.

According to another aspect of an embodiment of the present invention, there is provided a method performed by a second node in a wireless communication system, the method comprising: receiving a first message from a first node, wherein the first message carries indication information of whether the first node can enable a UE in an RRC inactive state to receive MBS service; and sending a second message to the first node.

According to the embodiment of the invention, the second message carries a message indicating whether the second node supports the UE in the RRC inactive state to receive MBS service.

According to still another aspect of an embodiment of the present invention, there is provided a node apparatus in a wireless communication network, including: a transceiver; and a processor coupled to the transceiver and configured to perform the method according to the above embodiments.

Technical effects

The invention provides a method and equipment for transmitting multicast service. The method and the equipment for transmitting the enhanced broadcast multicast service can ensure that the UE can receive the multicast data in the RRC inactive state, ensure continuous reception of the data and achieve the purpose of saving electricity for the UE.

Drawings

FIG. 1 is a system architecture diagram of System Architecture Evolution (SAE);

FIG. 2 is a schematic diagram of an initial overall architecture of FIG. 5G;

fig. 3 is an example of a first embodiment supporting multicast traffic transmission according to an embodiment of the present invention;

Fig. 4 is an example of a second embodiment supporting multicast traffic transmission according to an embodiment of the present invention;

Fig. 5 is an example of a third embodiment supporting multicast traffic transmission according to an embodiment of the present invention;

fig. 6 is an example of a fourth embodiment supporting multicast traffic transmission according to an embodiment of the present invention;

fig. 7 is an example of a fifth embodiment supporting multicast traffic transmission according to an embodiment of the present invention;

fig. 8 is an example of a sixth embodiment supporting multicast traffic transmission according to an embodiment of the present invention;

Fig. 9 is an example of a seventh embodiment supporting multicast service transmission according to an embodiment of the present invention; and

Fig. 10 is a block diagram of a network node device according to an embodiment of the invention.

Detailed Description

Figures 1 through 10, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will appreciate that the principles of the present disclosure may be implemented in any suitably arranged system or device.

Before proceeding with the description of the detailed description that follows, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term "couple" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms "transmit," "receive," and "communicate," and derivatives thereof, encompass both direct and indirect communication. The terms "include" and "comprise," as well as derivatives thereof, are intended to be inclusive and not limited to. The term "or" is inclusive, meaning and/or. The phrase "associated with" and its derivatives are intended to include, be included within, be connected to, be interconnected with, be included within, be connected to or be connected with, be coupled to or be coupled with, be able to communicate with, be co-operative with, be interwoven with, be juxtaposed with, be proximate to, be bound to or be in relation to, be bound to, be provided with an · attribute, be provided with an · relationship or be provided with a relationship with the · and the like. The term "controller" means any device, system, or portion thereof that controls at least one operation. Such a controller may be implemented in hardware, or in a combination of hardware and software and/or firmware. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. At least one of the phrases "..when used with a list of items means that different combinations of one or more of the listed items can be used and that only one item in the list may be required. For example, "at least one of A, B and C" includes any one of the following combinations: A. b, C, A and B, A and C, B and C, and A and B and C. For example, "at least one of A, B or C" includes any one of the following combinations: A. b, C, A and B, A and C, B and C, and A and B and C.

Furthermore, the various functions described below may be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or portions thereof adapted for implementation in a suitable computer readable program code. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium capable of being accessed by a computer, such as Read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), a hard disk drive, a Compact Disc (CD), a Digital Video Disc (DVD), or any other type of Memory. "non-transitory" computer-readable media exclude wired, wireless, optical, or other communication links that transmit transitory electrical or other signals. Non-transitory computer readable media include media that can permanently store data and media that can store and later rewrite data, such as rewritable optical disks or erasable memory devices.

The terminology used herein to describe embodiments of the application is not intended to limit and/or define the scope of the application. For example, unless otherwise defined, technical or scientific terms used in this disclosure should be given the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs.

It should be understood that the terms "first," "second," and the like, as used in this disclosure, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The singular forms "a," "an," or "the" and similar terms do not denote a limitation of quantity, but rather denote the presence of at least one, unless the context clearly dictates otherwise.

As used herein, any reference to "one example" or "an example," "one embodiment," or "an embodiment" means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" or "in one example" in various places in the specification are not necessarily all referring to the same embodiment.

As used herein, a "portion of an item" means at least some of the item, and thus may mean less than all of the item or all of the item. Thus, a "portion of an object" includes the entire object as a special case, i.e., the entire object is an example of a portion of an object.

It will be further understood that the terms "comprises" and "comprising," and the like, when used in this specification, specify the presence of stated features and advantages, but do not preclude the presence of other features and advantages, and that the terms "comprising" and "include" specify the presence of stated features and advantages, but rather than preclude the presence of other features and advantages. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.

The various embodiments discussed below for describing the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged wireless communication system. For example, although the following detailed description of embodiments of the present disclosure will be directed to LTE and 5G communication systems, it will be appreciated by those skilled in the art that the main gist of the present disclosure may be applied to other communication systems having similar technical contexts and channel formats with slight modifications without substantially departing from the scope of the present disclosure. The technical solution of the embodiment of the present application may be applied to various communication systems, for example, the communication system may include a global system for mobile communications (global system for mobile communications, GSM) system, a code division multiple access (code division multiple access, CDMA) system, a wideband code division multiple access (wideband code division multiple access, WCDMA) system, a general packet radio service (GENERAL PACKET radio service, GPRS), a long term evolution (long term evolution, LTE) system, an LTE frequency division duplex (frequency division duplex, FDD) system, an LTE time division duplex (time division duplex, TDD) system, a universal mobile communication system (universal mobile telecommunication system, UMTS), a worldwide interoperability for microwave access (worldwide interoperability for microwave access, wiMAX) communication system, a fifth generation (5th generation,5G) system, or a new radio (new radio, NR), etc. In addition, the technical scheme of the embodiment of the application can be applied to future-oriented communication technology. In addition, the technical scheme of the embodiment of the application can be applied to future-oriented communication technology.

The following description with reference to the accompanying drawings is provided to facilitate a thorough understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. The description includes various specific details to facilitate understanding but should be considered exemplary only. Accordingly, one of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and phrases used in the following specification and claims are not limited to their dictionary meanings, but are used only by the inventors to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following descriptions of the various embodiments of the present disclosure are provided for illustration only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

It should be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more such surfaces.

The terms "comprises" or "comprising" may refer to the presence of a corresponding disclosed function, operation or component that may be used in various embodiments of the present disclosure, rather than to the presence of one or more additional functions, operations or features. Furthermore, the terms "comprises" or "comprising" may be interpreted as referring to certain features, numbers, steps, operations, constituent elements, components, or combinations thereof, but should not be interpreted as excluding the existence of one or more other features, numbers, steps, operations, constituent elements, components, or combinations thereof.

The term "or" as used in the various embodiments of the present disclosure includes any listed term and all combinations thereof. For example, "a or B" may include a, may include B, or may include both a and B.

Unless defined differently, all terms (including technical or scientific terms) used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains. The general terms as defined in the dictionary are to be construed to have meanings consistent with the context in the relevant technical field, and should not be interpreted in an idealized or overly formal manner unless expressly so defined in the present disclosure.

Fig. 1 is an exemplary system architecture 100 for System Architecture Evolution (SAE). A User Equipment (UE) 101 is a terminal device for receiving data. An evolved universal terrestrial radio access network (E-UTRAN) 102 is a radio access network including macro base stations (enodebs/nodebs) providing an access radio network interface for UEs. The Mobility Management Entity (MME) 103 is responsible for managing the UE's mobility context, session context and security information. Serving Gateway (SGW) 104 mainly provides the functions of the user plane, and MME 103 and SGW 104 may be in the same physical entity. The packet data network gateway (PGW) 105 is responsible for charging, lawful interception, etc. functions, and may also be in the same physical entity as the SGW 104. A Policy and Charging Rules Function (PCRF) 106 provides quality of service (QoS) policies and charging criteria. The general packet radio service support node (SGSN) 108 is a network node device in the Universal Mobile Telecommunications System (UMTS) that provides a route for the transmission of data. A Home Subscriber Server (HSS) 109 is a home subsystem of the UE and is responsible for protecting user information including the current location of the user equipment, the address of the service node, user security information, packet data context of the user equipment, etc.

Fig. 2 is an exemplary system architecture 200 according to various embodiments of the present disclosure. Other embodiments of the system architecture 200 can be used without departing from the scope of this disclosure.

A User Equipment (UE) 201 is a terminal device for receiving data. The next generation radio access network (NG-RAN, or simply RAN) 202 is a radio access network that includes base stations (gnbs or enbs connected to the 5G core network 5GC, also called NG-gnbs) that provide access radio network interfaces for UEs. An access control and mobility management function (AMF) 203 is responsible for managing the mobility context of the UE, and security information. The User Plane Function (UPF) 204 mainly provides the functions of the user plane. The session management function entity SMF205 is responsible for session management. The Data Network (DN) 206 contains services such as operators, access to the internet, and third party traffic, among others. The interface between the AMF and the NG-RAN is called the NG-C interface, or the NG interface, or the N2 interface. The interface between the UPF and the NG-RAN is called the NG-U interface or the N3 interface, and the signaling between the UE and the AMF is called non-access stratum signaling (NAS), also called the N1 interface. The interface between base stations is called the Xn interface.

In order to effectively utilize the air interface resources, service data is provided to users by broadcasting and multicasting for services having multiple receiving users receiving the same data. Such services are referred to as multimedia broadcast multicast services, hereinafter referred to as MBS (Multicast and Broadcast Service).

The MBS service is divided into two types, one is a multicast service, and then when the multicast service starts, if the UE is in PMM idle mode, the network sends a paging message to let the UE enter PMM connection mode to receive the service. One is a broadcast service, the UE does not need to join a certain group, the service start information, the configuration information can be sent to the UE by broadcasting, and all PMM connection modes and PMM idle modes can receive data.

When MBS is broadcast service, base station adopts broadcast mode to send data to UE, UE in RRC idle and connection mode can receive MBS service data. When the base station is in a split architecture, the distribution unit DU (Distributed Unit) is provided with information related to the MBS by the CU-CP, and the DU generates an MBS control message, an MBS broadcast configuration message, which is transmitted to the UE through a common channel, for example, through the MCCH. For multicast service, CU-CP sends the relevant configuration information of MBS to UE through RRC message, only UE in RRC connection mode can receive data of MBS service.

The UE has a limited power, and if the UE has no other service, it is unnecessary to put the UE in a Radio Resource Control (RRC) connected mode to receive data, and the UE may enter an RRC inactive state to receive data of a multicast service by means of Discontinuous Reception (DRX) in order to save power of the UE.

The node related to the invention comprises:

The first node, the second node, and the third node include, but are not limited to, at least one of the following: source base station, destination base station, core network node, base station Central Unit CU (CU), base station distribution Unit DU (gNB distributed Unit DU) or base station Central Unit user plane (gNB CU-UP), etc.

Fig. 3 depicts a first embodiment supporting multicast traffic transmission. The first node, for example, the first base station, stores a UE context, where the UE context is for one UE, the UE context includes an identifier of the UE, capability information of the UE, information of a radio bearer of the UE, and information of a multicast service added by the UE, for example, a multicast session identifier TMGI added by the UE. After knowing the multicast service added by the UE, if the UE is the first UE to join the service, the first base station initiates a process of establishing a user plane with the core network, that is, sends a distribution establishment request message to the core network, and the core network sends a distribution establishment response message to the first base station. In the process of establishing the user plane, the first base station further obtains more multicast service information, such as a service range of the multicast service, an identifier of a quality flow (QoS flow) and a quality requirement (QoS) parameter contained in the multicast service, and multicast service status information, from the core network. The multicast service status information indicates whether the service indicated by the TMGI is active or inactive. The first base station stores information of multicast service, i.e. context information of MBS, the context of which is for one MBS service.

In step 301, a first base station sends a first message to a second node, e.g. a second base station.

The first base station determines that the UE enters an RRC inactive state, and the first base station can determine that some UEs enter the RRC inactive state to receive MBS services according to the capability of the UE, whether other unicast services are required to be received by the UE or not, the load condition of a cell, the service state of the MBS and other information.

In the present invention, if a UE in an RRC inactive state is to receive MBS service in the area, all base stations in the area are to maintain MBS data transmission, and even if a certain base station has no RRC connected mode user and no RRC inactive state UE, the other base stations in the area are to continue to save MBS context, not release MBS resources, and continue MBS data transmission because the other base stations in the area have RRC inactive state UEs. For this purpose, the first base station transmits a message to the second base stations within the area.

In one embodiment, the message may be a UE-specific message, such as an inactive UE context setup request, or an inactive UE context modification request, or other name. The message includes the identifier of XnAP allocated by the first base station to the UE, and may further include indication information that the UE enters the RRC inactive state. The method also can comprise the session identification of the MBS added by the UE, the state information of the MBS and the configuration information of MBS Radio Bearer (MRB). The configuration information of the MBS radio bearer at least includes an MRB identifier, and may further include information of QoS flows, qoS information, PDCP Sequence Number (SN) length, and the like.

In one embodiment, the second node and the first node belong to the same regional scope.

In another embodiment, the message sent by the first base station to the second base station may also be an MBS multicast dedicated message, such as a multicast activation request message, or a multicast context establishment request message, or a multicast context modification request message, or a multicast bearer establishment request message, or other names. The message contains the identity of XnAP allocated by the first base station for the MBS. The message sent by the first base station to the second base station may also be a public message, where the first message further includes a node identifier of the first base station. The message sent by the first base station is used to inform the second base station that, within a range of an area, there is a UE in an RRC inactive state receiving MBS service. In order to reduce the number of transmitted messages, the first base station may also transmit a message to the second base station within the area when the MBS is in the active state. The first base station may learn that the MBS is in an active state from the service state of the MBS received by the core network, or when the first base station receives an MBS activation request message sent by the core network. The message sent by the first base station to the second base station carries information about the UE in the RRC inactive state, specifically, the message includes one or more of the following information:

-an identity of the UE. The identity of the UE receiving MBS data in the RRC inactive state, e.g. the C-RNTI, or the RAN UE paging identity I-RNTI, or an identity allocated by the first base station to this UE. Here, the UE identifier may be a UE identifier list, which indicates identifiers of a plurality of UEs receiving MBS data in an RRC inactive state.

-Number of UEs. The number of UEs receiving MBS data in the RRC inactive state is, for example, at least 1 UE in the RRC inactive state.

-Indication information indicating that a UE in an RRC inactive state exists within a range of the area, e.g. a UE in an RRC inactive state exists within the first node to which it belongs or within the range of the area to which the first node belongs.

-MBS session identification. Such as a TMGI, indicating the multicast session identity received by the UE in the inactive state.

-Service status of MBS. The traffic state indicates whether the multicast traffic is active or inactive.

-An identification of MBS radio bearer MRB. An identification of a radio bearer used to identify transmission of MBS data over the air. This is the identity of the radio bearer allocated by the first base station for transmitting the MBS service.

Configuration information of MBS radio bearers. The configuration information of the MBS radio bearer at least comprises MRB identification, and can also comprise information of QoS flow, qoS information, RLC information, PDCP SN length and the like on the MRB.

-A regional scope. The area range may be a RAN paging range, or a list of identities of a group of cells, or an identity of a predetermined range. The region range indicates that the UE having the RRC inactive state in this region is receiving MBS service.

MBS service range. The service range of the MBS is indicated, and is an identity of a set of cells, or a set of routing area identities.

-Whether the RRC inactive state UE is supported to receive indication information of MBS service. The node that transmitted the message is indicated whether to have a function of letting the UE enter the RRC inactive mode to receive the MBS service.

-Indication information that MBS context information and/or configuration information is kept on.

The second base station receives the message and stores the information in the context of the UE or in the context of the MBS. The UE served by the second base station currently has no UE to receive the multicast service, but since there is a UE to receive the multicast service in the area, if the second base station has not established a user plane for transmitting the MBS service with the core network, the second base station sends a distribution establishment request message to the core network, and establishes the user plane of the MBS service between the base station and the core network.

The second base station stores information about the UE in the RRC inactive state, for example, stores the identity of the UE, or the number of UEs in the RRC inactive state. The second base station knows that the UE with RRC inactive state in the area is to receive MBS service, the second base station does not delete the user plane between the base station and the core network for receiving the MBS service, and continues to send the MBS service data on the MBS radio bearer. Even if the second base station does not have the UE to receive the MBS service, since it is known that the UE in the RRC inactive state on the first base station is to receive the MBS service, the UE in the inactive state may move to the second base station without notifying the second base station, and the second base station is to save the received context of the UE in the inactive state, keep the MBS context information, continue multicast data transmission, and cannot release the signaling connection of the MBS and the resources of the user plane.

The second base station may refer to the configuration information of the MRB transmitted by the first base station, and the second base station may configure the same MRB to transmit data of the multicast service. The second base station also broadcasts configuration information of the MRB configured for the UE in the inactive RRC state to receive the MBS on the air interface.

Step 302, the second base station sends a second message to the first base station.

The second base station transmits a second message, which may be a response message to the first message, to the first base station. The message may contain information of the UE in the RRC inactive state held at the second base station.

If the first message is a message for one UE at step 301, the second message is also for one UE. The second message includes the identifier XnAP allocated to the UE by the second base station, and the identifier XnAP allocated to the UE by the first base station. The method also comprises a session identifier of the MBS added by the UE, and configuration information of MBS Radio Bearer (MRB) configured by the second base station for the session. The configuration information is for a cell on the second base station, and therefore the second message also contains an identity of the cell. The configuration information of the MBS radio bearer at least includes an MRB identifier, and may further include information of QoS flows, qoS information, PDCP Sequence Number (SN) length, and the like. The first base station receives the configuration information of the MBS radio bearer configured by the second base station, where the first base station may include the configuration information of the MBS radio bearer configured by the second base station or a cell on the second base station in the broadcast information. Namely, the broadcast information of the first base station contains MBS session identification or indication information for identifying a certain session, cell identification of a neighboring cell and MRB configuration information of the cell. Or the first base station sends an RRC reconfiguration request message to the UE, wherein the message comprises the cell identification of the adjacent cell and MRB configuration information for a certain MBS session on the cell. The UE receives the configuration information of the neighboring cell, and when the UE is in the RRC inactive state and moves to the cell, the UE can continuously receive the MBS data without entering the RRC connection state.

If the message in step 301 is a message for MBS, the response message includes the identifier of XnAP allocated by the second base station for MBS, the identifier of XnAP allocated by the first base station for MBS, and if the message in step 301 is a public message, the second message also includes the node identifier of the second base station. In addition, the second message may contain one or more of the following information:

-an identity of the UE. The identity of the UE receiving MBS data in the RRC inactive state, e.g. the C-RNTI, or the RAN UE paging identity I-RNTI, or an identity allocated by the first base station to this UE.

-Number of UEs. The number of UEs receiving MBS data in the RRC inactive state is, for example, at least 1 UE in the RRC inactive state. Here, the UE identifier may be a UE identifier list, which indicates identifiers of a plurality of UEs receiving MBS data in an RRC inactive state. Here, the UE identifier may be a UE identifier list, which indicates identifiers of a plurality of UEs receiving MBS data in an RRC inactive state.

-An identification of MBS radio bearer MRB. An identification of a radio bearer used to identify transmission of MBS data over the air.

The first base station obtains the information of the UE in the RRC non-activated state on the second base station, and stores the information in the MBS context.

The first base station may refer to the configuration information of the MRB transmitted by the second base station, and the first base station may configure the same MRB to transmit the data of the multicast service. The first base station also broadcasts configuration information of the MRB configured for the UE in the inactive RRC state to receive the MBS on the air interface.

When the first base station has no UE to receive MBS service, the UE includes an RRC connection state and an RRC inactive state, and there is no UE to receive MBS service on all the second base stations within the area range, the first base station may delete the user plane between the first base station and the core network, delete the resources of the MBS radio bearer on the base station, and stop broadcasting the configuration information of the MBS radio bearer on the air interface.

By the method of the embodiment, the first base station and the second base station can be ensured to prepare MBS resources in advance or keep the MBS resources not deleted for the UE in the RRC inactive state to receive the MBS multicast data normally in the inactive state, so that the purpose of saving electricity of the UE is achieved.

Fig. 4 depicts a second embodiment supporting multicast traffic transmission. The first node, e.g. the first base station, stores the context of the UE, which stores information of the multicast service the UE joins, e.g. the multicast service identity TMGI the UE joins has already been stored in the context of the UE. In addition, after knowing the multicast service added by the UE, if the UE is the first UE added to the service, the first base station initiates a process of establishing a user plane with the core network, that is, sends a distribution establishment request message to the core network, and the core network sends a distribution establishment response message to the first base station. In the process of establishing the user plane, the first base station further obtains more multicast service information, such as a service range of the multicast service, an identifier of a quality flow (QoS flow) and a quality requirement (QoS) parameter contained in the multicast service, and multicast service status information, from the core network. The multicast service status information indicates whether the service indicated by the TMGI is active or inactive. The first base station stores information of the multicast service, i.e., context information of the MBS.

In step 401, the first base station sends a message to a second node, e.g. a second base station.

The first base station is configured with a regional area, e.g. a RAN paging area for a UE, which may contain an identification list of a set of cells or a set of RAN regional identifications, within which a central base station is also configured. In this embodiment, the second base station is a central base station. The first base station sends a message to the second base station.

In one embodiment, the message may be a UE-specific message, such as an inactive UE context setup request, or an inactive UE context modification request, or other name. The message includes an identifier of the F1AP allocated by the first base station to the UE, and may further include indication information that the UE enters the RRC inactive state. The method also can comprise the session identification of the MBS added by the UE, the state information of the MBS and the configuration information of MBS Radio Bearer (MRB). The configuration information of the MBS radio bearer at least includes an MRB identifier, and may further include information of QoS flows, qoS information, PDCP Sequence Number (SN) length, and the like.

In another embodiment, the message sent by the first base station to the second base station may also be a message dedicated to MBS multicast service, such as a multicast context establishment request message or a multicast context modification request message or other names. The message contains the identity of XnAP allocated by the first base station for the MBS. The message sent by the first base station to the second base station may also be a public message. The message sent by the first base station is used to notify the second base station, and in the range of the area, the UE in the RRC inactive state receives the MBS service. In order to reduce the number of transmitted messages, the first base station may also transmit a message to the second base station within the area when the MBS is in the active state. The first base station may learn that the MBS is in an active state from the service state of the MBS described above, or when the first base station receives an MBS activation request message sent by the core network. The message sent by the first base station to the second base station carries information about the UE in the RRC inactive state, specifically, one or more of the following information is included:

-A regional scope. The area range may be a RAN paging range, or a list of identities of a group of cells, or an identity of a predetermined range.

The second base station sends a message to a third node, e.g., a third base station, step 402.

The second base station receives the message and stores the information in the context of the UE or in the context of the MBS. The second base station notifies the information of the RRC inactive state UE to other base stations in the area. The second base station may send 402 the message of step 402 to other base stations in the predetermined area after receiving the message of the first base station. Or receiving an activation request message sent by the core network at the second base station, and sending the message of step 402 to other base stations in the predetermined area. The message may contain information about all RRC inactive state UEs within a specific area obtained by the second base station, and in particular, the message may contain one or more of the following information:

-Indication information indicating that a UE in an RRC inactive state receives multicast traffic indicated by an MBS session identity within a range of a zone (e.g. within the range of the first node to which the UE belongs or within the range of the zone to which the first node belongs).

The third base station receives the message, and stores the information in the context of the UE or in the context of the MBS. If the third base station does not establish the user plane of MBS with the core network, the third base station sends a distributing establishment request message to the core network, and establishes the user plane of MBS service between the base station and the core network.

The third base station stores the received information of the inactive UE, for example, stores the identity of the UE, or the number of UEs in the RRC inactive state. The third base station knows that the UE with RRC inactive state in the area is to receive MBS service, the third base station does not delete the user plane between the base station and the core network for receiving the MBS service, and continues to send the data of MBS service on the radio bearer of MBS. Even if the third base station does not have the UE to receive the MBS service, because the second base station obtains the message sent by the second base station, it is known that the UE having the RRC inactive state is to receive the MBS service in the predetermined area, and the UE in the inactive state may move to the third base station without notifying the third base station, and the third base station cannot release the signaling connection of the MBS and the resources of the user plane.

The third base station may refer to the configuration information of the MRB transmitted by the second base station, and the third base station may configure the same MRB to transmit the data of the multicast service.

In step 403, the third base station sends a response message to the second base station.

In the response message, the third base station may also notify the second base station, whether there is configuration information of the MRB of the inactive UE transmitting the multicast service on the third base station and/or on the receiving multicast service on the third base station. I.e. contains 402 the information described in the step message.

By the method of the embodiment, through the central base station, the base station in the same area can be ensured to prepare MBS resources in advance or keep the MBS resources not deleted for the UE in the RRC inactive state to receive the multicast data, so that the UE can normally receive the MBS multicast data in the inactive state, and the purpose of saving electricity for the UE is achieved.

Fig. 5 depicts a third embodiment supporting multicast traffic transmission. The first node, e.g. the concentration unit CU, keeps the context of the UE, CU is part of a separate base station, in which case the base station is divided into the concentration unit CU, the distribution unit DU, CU may be further divided into a control plane (CU-CP) and a user plane (CU-UP). Hereinafter, CU may also be referred to as CU-CP. The CU keeps the context of the UE and the context of the MBS. The context of a UE is for one UE and the context of an MBS is for one MBS service. The context of the UE includes an identity of the UE, capability information of the UE, information of a radio bearer of the UE, information of a multicast service to which the UE is added, for example, a multicast session identity TMGI to which the UE is added. The multicast service identifier added by the UE is sent to the CU by the core network, for example, the MBS session identifier list is carried by a PDU session resource establishment request message or a PDU session resource modification request message. After the CU knows the multicast service added by the UE, if the UE is the first UE added to the service, the CU initiates the establishment process of the user plane between the CU and the core network, namely, the CU sends a distribution establishment request message to the core network, and the distribution establishment request message carries MBS session identification and transmission layer address information of the shared NG-U. The core network sends a distributing and establishing response message to the CU, the message contains more multicast service information, the message carries MBS session identification, quality flow (QoS flow) identification and quality requirement (QoS) parameters contained in the multicast service, and multicast service state information. The multicast service status information indicates whether the service indicated by the TMGI is active or inactive. After the CU obtains the information, the CU saves the information in the context information of the MBS.

In step 501, the cu sends a message to a second node, e.g. a DU.

The CU decides that the UE enters the RRC inactive state, and the CU can decide that some UE enters the RRC inactive state to receive the MBS service according to the capability of the UE, whether the UE has other unicast service to receive or not, the load condition of a cell, the service state of the MBS and other information.

The CU sends a message to the DU, the message carrying information about the UE in the RRC inactive state.

In one embodiment, the message may be a UE-specific message, such as an inactive UE context setup request, or an inactive UE context modification request, or a UE context modification request message, or other name. The message contains the identifier of the F1AP allocated by the CU to the UE and/or the identifier of the F1AP allocated by the DU to the UE, and the indication information that the UE enters the RRC inactive state. The method also can comprise the session identification of the MBS added by the UE, the state information of the MBS and the configuration information of MBS Radio Bearer (MRB). Wherein, the configuration information of the MBS radio bearer at least comprises MRB identification. After receiving the information, the DU stores the information in the context of the UE, and records that the state of the UE is an RRC inactive state.

In another embodiment, the CU's message sent to the DU may also be an MBS multicast service specific message, such as a multicast context setup request message or a multicast context modification request message or other names. The message contains the identification of the F1AP allocated by the CU for MBS and/or the identification of the F1AP allocated by the DU for MBS. The CU sends a message to the DU to inform the DU that there is a UE in an RRC inactive state receiving MBS service within the range of the DU, or within a cell on the DU, or within an MBS multicast service area. In order to reduce the number of transmitted messages, the CU may also transmit the message to the DU when the MBS is in an active state. The CU may learn that the MBS is in an active state from the service state of the MBS received by the core network, or when the CU receives an MBS activation request message sent by the core network. The CU sends a message to the DU carrying one or more of the following information:

MBS session identity, e.g. TMGI.

The area identification information may be MBS service area information or identification information of a cell.

The information of the RRC inactive user may be the number of users receiving the MBS service in the RRC inactive state, or an identification list of the UE receiving the MBS service in the RRC inactive state, or an indication that the RRC inactive user exists in the DU or the range indicated by the area identification on the DU. And receiving the information of the RRC inactive user, wherein the DU keeps the MBS context information, does not initiate the multicast context release request message, and does not initiate the multicast distribution release request message.

MBS state information. The MBS state is indicated to be an active state, and the active state is to notify the DU that the DU needs to maintain configuration information of MBS data and continue transmission of the MBS data. And after receiving the MBS state information, the DU keeps the MBS context information, does not initiate the multicast context release request message, and does not initiate the multicast distribution release request message.

-The UE in RRC inactive state receiving indication information of MBS. The indication information indicates that the CU supports or enables or configures the UE to enter an inactive state to receive MBS service. And after receiving the indication information, the DU keeps the MBS context information, does not initiate the multicast context release request message, and does not initiate the multicast distribution release request message.

-Indication information that MBS context information and/or configuration information is kept on. And after receiving the indication information, the DU keeps the MBS context information, does not initiate the multicast context release request message, and does not initiate the multicast distribution release request message.

-Configuration information of MBS Radio Bearers (MRBs). The configuration information of the MBS radio bearer at least includes an MRB identifier, and may further include information of QoS flows, qoS information, PDCP SN length, and the like.

The DU sends a response message to the CU, step 502.

According to the message of step 501, the DU sends a response message to the CU. If the message in step 501 is a message for UE, the response message includes the identifier of the F1AP allocated by CU to UE, and the identifier of the F1AP allocated by DU to UE.

If the message in step 501 is a message for MBS, the response message includes the identifier of the F1AP allocated by the CU for MBS, and the DU is the identifier of the F1AP allocated by MBS.

Through the method of the embodiment, the DU can keep sending MBS data through the message sent by the CU, so that the UE normally receives MBS multicast data in an inactive state, and the purpose of saving electricity of the UE is achieved.

Fig. 6 depicts a fourth embodiment supporting multicast traffic transmission. The first node, e.g. a central control node CU in the access network, keeps the UE context and the MBS context. The context of a UE is for one UE and the context of an MBS is for one MBS service. The context of the UE includes an identity of the UE, capability information of the UE, information of a radio bearer of the UE, information of a multicast service to which the UE is added, for example, a multicast session identity TMGI to which the UE is added. The multicast service identifier added by the UE is sent to the CU by the core network, for example, the MBS session identifier list is carried by a PDU session resource establishment request message or a PDU session resource modification request message. After the CU knows the multicast service added by the UE, if the UE is the first UE added to the service, the CU initiates the establishment process of the user plane between the CU and the core network, namely, the CU sends a distribution establishment request message to the core network, and the distribution establishment request message carries MBS session identification and transmission layer address information of the shared NG-U. The core network sends a distributing and establishing response message to the CU, the message contains more multicast service information, the message carries MBS session identification, quality flow (QoS flow) identification and quality requirement (QoS) parameters contained in the multicast service, and multicast service state information. The multicast service status information indicates whether the service indicated by the TMGI is active or inactive. After the CU obtains the information, the CU saves the information in the context information of the MBS.

The CU can decide to let some MBS UE enter the RRC inactive state to receive MBS service data, and can decide that some MBS UE enter the RRC inactive state according to the capability of the UE, whether other unicast services are required to be received or not according to the load condition of a cell, the service state of the MBS and other information. The UE enters the RRC inactive state, meaning that the CU sends an RRC release request to the UE, the RRC release request message indicating that the UE is to be in the RRC inactive state. And the UE entering the RRC inactive state can receive the broadcast message, move in the paging range of the Radio Access Network (RAN), does not need to inform a base station, can not send or receive data of unicast service, and only stores the context information of the UE in the CU. In order to let the UE enter the RRC inactive state, the CU sends a UE context release request message to the DU, releasing the information of the UE on the DU.

Step 601: the CU sends a message to the second node, e.g., a DU.

The message in step 601 may be a UE context release request, where the message includes an identifier of an F1AP allocated by a CU to the UE, an identifier of an F1AP allocated by a DU to the UE, and a reason for release, and in the present invention, the message further includes an MBS session identifier, for example, a TMGI, and the message further includes indication information, which indicates that the MBS session state on the DU is an active state, or indicates that the context information of the MBS needs to be kept, or indicates that the DU does not need to delete the context information of the MBS. The context information contains information or resources of the control plane and the user plane.

If all MBS users on the DU enter the RRC inactive state, or all MBS users on a cell on the DU enter the RRC inactive state, the DU releases the contexts and resources of the MBS, so that the UE in the RRC inactive state cannot correctly receive the MBS data, in order to avoid this problem, the CU determines that, at the time of the last UE context release request or before the last UE context release request is sent, the CU sends a message to the DU informing the DU that the MBS session state on the DU is the active state, or that the context information of the MBS needs to be kept, or that the DU does not delete the context information of the MBS.

In another embodiment, before step 601, the CU may also send an MBS-related message 600, e.g. the message name is a multicast modification request message or others, the message carrying one or more of the following information:

MBS session identity, e.g. TMGI.

-The UE in RRC inactive state receiving indication information of MBS service. The indication information indicates that the CU supports or enables or configures the UE to enter an inactive state to receive MBS service. And after receiving the indication information, the DU keeps the MBS context information, does not initiate the multicast context release request message, and does not initiate the multicast distribution release request message.

After receiving the message, the DU keeps the multicast context information, and when the multicast UE context does not exist, the DU continues to send the multicast service data, does not initiate the multicast context release request message to the CU, and does not initiate the multicast distribution release request message to the CU.

After that, the CU may send 601 a message of step 601, a UE context release request message, to release the multicast UE context stored by the DU. Even if the contexts of all UEs to receive the multicast data are released, the DU continues to transmit data of the multicast service until the message of the multicast context release request transmitted by the CU of step 803 is received.

Step 602: the DU sends a response message to the CU.

The DU transmits a response message corresponding to the 601 message. The receipt of the message of step 601 is acknowledged.

Step 603: the CU sends a multicast context release command message to the DU.

When there is no UE on the CU to receive MBS service, i.e. there is no UE in RRC connected mode to receive MBS service, and there is no UE in RRC inactive mode to receive MBS service from the DU, the CU may send a multicast context release order message to the DU, including the reason for release. The reason for the release may indicate that no user is to receive the MBS service, and at this time, no user means that neither the RRC connected mode UE nor the RRC inactive mode UE is to receive the MBS service. Upon receiving the message, the DU may delete the context of the MBS, delete the resources of the signaling plane and the user plane related to the MBS, and stop transmitting the control information and the user data of the MBS on the air interface.

Step 604: the DU sends a multicast context release complete message to the CU.

And after receiving 603 the message of step, the DU releases all signaling connection, releases user plane transmission resources related to multicast, and sends a multicast context release complete message to the CU.

Fig. 7 depicts a fifth embodiment supporting multicast traffic transmission. In the process that the first node, such as a DU, initiates the multicast service release request, the second node, such as a CU, instructs the DU to continue transmitting multicast service data.

701: The DU sends a message to the CU.

The DU stores the context information of the user to receive the MBS service, and in the context of the UE, the identification of the MBS radio bearer MRB is stored. The bearer indicated by the MRB identity is associated with one MBS session. The DU knows the relationship between MBS session and MRB through the multicast context setup request message sent by the CU, and saves this relationship in the MBS context. When there is no UE on the DU to receive the MBS service, i.e. after all contexts of the user to receive a certain MRB are deleted, the DU may send 701 a message about MBS release to the CU, and the message of step 701 may be a multicast context release request message, or a distribution release command message, or other message names.

The message of step 701 about MBS release, i.e. multicast context release request message, or distribution release command message, or other message name, contains the identity of the F1AP allocated by the CU for MBS, and the identity of the F1AP allocated by the DU for MBS, including the reason of release. The reason for the release may indicate that no user is to receive MBS service. Through the identification of the F1AP allocated by the CU to the MBS, the CU can know which MBS service, and no user on the DU is to receive the MBS service.

702: The CU sends a failure response message to the DU.

The CU knows which MBS service, no user is on the DU to receive the MBS service, for which the CU also holds the UE context for receiving the service data and being received by the RRC non-active UE, some RRC non-active UEs need to receive the MBS data from the DU, or the CU knows that, within a certain predetermined range, there are also RRC non-active UEs to receive the MBS data, and the CU sends a failure message as a response message of the step 701 message. The failure response message may carry indication information, indicating that there is an RRC inactive mode UE, indicating that the DU maintains MBS context information, that the DU continues transmission of multicast data, does not release signaling resources and user plane resources of the multicast service, and does not initiate a multicast context release request message or distribute a release command message to the CU.

By the method of the embodiment, the CU refuses the release request of the DU, so that the DU can continuously keep sending MBS data, and the UE can normally receive MBS multicast data in an inactive state, thereby achieving the purpose of saving electricity of the UE.

Fig. 8 depicts a sixth embodiment supporting multicast traffic transmission. In the process of establishing the F1 interface, the CU indicates DU, the CU supports the UE to enter the RRC inactive state to receive MBS data, the DU indicates the CU, and the DU supports the transmission of multicast data when the MBS UE context does not exist.

801: The first node, e.g., a DU, sends an F1 setup request message.

The DU initiates the establishment of the F1 interface by sending an F1 SETUP REQUEST message including the appropriate data to the second node, e.g. the CU. The exchanged data is stored in the respective nodes. When this process is complete, the F1 interface may run and other F1 messages may be exchanged.

The DU should include DU system information and a slice support list in the F1 setup request message, including RAN area codes, and may further include information of a serving cell, where the information of the serving cell includes a physical layer identifier of the cell, and a cell unique identifier includes all MBS frequency selection area identifiers related to the cell.

The F1 setup request message further includes indication information indicating whether the DU has a function of letting the UE receive the MBS service in the RRC inactive state. The DU has the function, can keep the transmission of multicast data on the DU, keep the multicast context, and even if the DU does not store the context information of MBS UE, the DU still transmits the multicast data, does not release signaling resources and user plane resources of multicast service, and does not initiate multicast context release request information or distribute release command information to CU. The indication information may also be included in a DU configuration update request message.

802: The CU sends an F1 setup response message.

The CU responds with an F1 setup response message that includes the appropriate data. F1 setup response message includes the cell list to be activated. The method also comprises indication information for indicating whether the CU has the function of enabling the UE to receive the MBS service in the RRC inactive state. The CU has this function and can decide to let the UE in RRC connected mode enter RRC inactive state to receive some MBS multicast data, in some embodiments, the CU has this function and can decide whether to release the resources related to this MBS resource on the CU and DU according to whether the UE in RRC inactive mode is receiving MBS in the neighboring cell. The indication information may also be included in the CU configuration update request message.

By the method of the embodiment, the CU can determine whether the CU supports the function of enabling the UE to receive the MBS service in the RRC inactive state or not by acquiring the DU, and the CU can enable some UEs to enter the RRC inactive state to receive the MBS service, so that the purpose of saving electricity for the UE is achieved.

Fig. 9 depicts a seventh embodiment supporting multicast traffic transmission. In the process of establishing the multicast context, the CU indicates DU, the CU supports the UE to enter the RRC inactive state to receive MBS data, the DU indicates the CU, and the DU supports the transmission of the multicast data when the MBS UE context does not exist. The indication information may be for a certain MBS multicast service or for all MBS multicast services.

901: The first node, e.g., a CU, sends a multicast context establishment request message to the second node, e.g., a DU.

The multicast context establishment request message contains the identifier of the F1AP allocated by the CU for MBS, the multicast session identifier, the service range of multicast and the configuration information of the multicast radio bearer to be established. The message also contains indication information, which indicates that the CU supports or enables or configures the UE to enter the inactive state to receive the MBS service. When the indication information is received, the DU keeps the multicast context information, and when the multicast UE context does not exist, the transmission of the multicast service data is continued, the multicast context release request message is not initiated to the CU, and the multicast distribution release request message is not initiated to the CU.

902: The DU sends a multicast context setup response message to the CU.

The multicast context establishment response message contains the identification of the F1AP allocated by the DU for the MBS, the identification of the F1AP allocated by the CU for the MBS, and the identification of the successful MBS radio bearer is established. The message also contains indication information indicating whether the DU has a function of letting the UE receive MBS service in the RRC inactive state. The DU has the function, can keep the transmission of multicast data on the DU, keep the multicast context, and even if the DU does not store the context information of MBS UE, the DU still transmits the multicast data, does not release signaling resources and user plane resources of multicast service, and does not initiate multicast context release request information to CU.

The CU knows the DU specific function and can decide to let some UEs enter RRC inactive mode to receive MBS multicast service.

Fig. 10 is a block diagram of a node device in a network according to the present invention.

Node devices in the network may be used to implement the DUs, CU-UPs, CU-CP, gNB, eNB source base stations, destination stations, source DUs, source CU-UPs, source CU-CPs, destination DUs, destination CU-UPs, destination CU-CPs, master base stations, secondary base stations, OAM, UDM, AMF, SMF, UPFs, or the like of the present invention. Referring to fig. 10, a network device according to the present invention includes a transceiver 1010, a controller 1020, and a memory 1030. The transceiver 1010, controller 1020, and memory 1030 are configured to perform the operations of the methods and/or embodiments of the present invention. Although the transceiver 1010, the controller 1020, and the memory 1030 are shown as separate entities, they may be implemented as a single entity, such as a single chip. The transceiver 1010, the controller 1020, and the memory 1030 may be electrically connected or coupled to each other. The transceiver 1010 may transmit and receive signals to and from other network node devices, such as UEs, base stations, or core network nodes. The controller 1020 may include one or more processing units and may control the network device to perform operations and/or functions in accordance with one of the embodiments described above. Memory 1030 may store instructions for implementing the operations and/or functions of one of the embodiments described above.

Thus, the method and the device for supporting multicast service transmission according to the embodiment of the application are completed. The method and the equipment can enable the UE to receive the MBS data in the RRC inactive state, thereby achieving the effect of saving the energy of the UE.

Those skilled in the art will appreciate that the above illustrative embodiments are described herein and are not intended to be limiting. It should be understood that any two or more of the embodiments disclosed herein may be combined in any combination. In addition, other embodiments may be utilized and other changes may be made without departing from the spirit and scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are contemplated herein.

Those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and steps described herein may be implemented as hardware, software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such design decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits described herein may be implemented or performed with a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a field programmable gate array (Field Programmable GATE ARRAY, FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the disclosure herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the application, which is defined by the appended claims.

Claims

1. A method performed by a second node in a wireless communication system, the method comprising:

Receiving a first message from a first node, wherein the first message carries relevant information of the UE in an RRC inactive state; and

Processing is performed based on the first message.

2. The method of claim 1, wherein the information regarding the UE in the RRC inactive state comprises one of:

An identification of the UE;

Number of UEs;

indication information of the UE having the RRC inactive state;

session identification of MBS added by UE;

status information of MBS;

Configuration information of MBS Radio Bearers (MRBs);

A regional scope;

3. The method of claim 2, wherein the regional area is a RAN paging area or a predetermined cell list.

4. A method as claimed in any one of claims 1 to 3, wherein the second node and the first node belong to the same regional scope.

5. The method according to any one of claims 1 to 4, wherein the UE indication information that the RRC non-active state exists indicates that the UE that the RRC non-active state exists within the range of the first node or within the range of the area to which the first node belongs.

6. The method of any of claims 1 to 5, wherein the first message is a UE-specific message.

7. The method of any of claims 1 to 5, wherein the first message is one of:

multicast dedicated messages for MBS;

public messages.

8. The method of any of claims 1 to 7, wherein the processing comprises at least one of:

The second node maintains UE context information;

The second node keeps MBS context information;

the second node continues to transmit multicast data;

9. The method according to any of claims 1 to 8, wherein the RRC inactive state of UEs is at least 1.

10. The method according to any of claims 1 to 9, wherein the UE in the RRC inactive state is in a first node or a range of areas to which the first node belongs.

11. The method of any of claims 1 to 10, if the second node is a base station, the processing further comprising at least one of:

Sending a request for establishing a user plane to a core network;

12. The method of claim 11, wherein the third message includes information about the UE in the RRC inactive state of the second node and/or information about the received UE in the RRC inactive state of the other node.

13. The method of claim 12, wherein the received other nodes are at least 1.

14. The method according to any of claims 11 to 13, wherein the second node receives a response message from the third node, the response message carrying information about UEs in an RRC inactive state of the third node.

15. The method of claim 14, wherein the MRB configuration information carried in the response message is the same as the MRB configuration information carried in the third message.

16. The method according to any of claims 1 to 15, wherein the second node is a base station, a distribution unit DU or a concentration unit CU and the first node is a base station or a concentration unit CU.

17. A method performed by a second node in a wireless communication system, the method comprising:

Receiving a first message from a first node, wherein the first message carries indication information of whether the first node can enable a UE in an RRC inactive state to receive MBS service;

And sending a second message to the first node.

18. The method of claim 17, wherein the second message carries a UE indicating whether the second node supports an RRC inactive state to receive MBS service.

19. A node device in a wireless communication network, comprising:

A transceiver; and

A processor coupled to the transceiver and configured to perform the method according to one of the preceding claims 1-18.