WO2023121387A1

WO2023121387A1 - Method for transmission of broadcast service supporting multimedia broadcast multicast service mbs

Info

Publication number: WO2023121387A1
Application number: PCT/KR2022/021180
Authority: WO
Inventors: Hong Wang; Lixiang Xu; Weiwei Wang
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2021-12-23
Filing date: 2022-12-23
Publication date: 2023-06-29
Also published as: CN116390173A

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The method performed by a user equipment (UE) in a wireless communication system is provided. the method includes receiving, from a distributed unit (DU) of the base station, a F1 setup request message including served cell information indicating an service area identity of multimedia broadcast multicast service (MBS) service; and transmitting, to the DU, a F1 setup response message in response to the F1 setup request message.

Description

METHOD FOR TRANSMISSION OF BROADCAST SERVICE SUPPORTING MULTIMEDIA BROADCAST MULTICAST SERVICE MBS

The application relates generally to the field of communication, and more particularly, to a method for transmission of broadcast service supporting multimedia broadcast multicast service (MBS).

5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in “Sub 6GHz” bands such as 3.5GHz, but also in “Above 6GHz” bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz (THz) bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

Moreover, there has been ongoing standardization in air interface architecture/protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture/service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

There are needs to enhance procedures for broadcast service supporting MBS in a wireless communication system.

According to an aspect of the present disclosure, there is provided a method for transmission of broadcast service supporting multimedia broadcast multicast service MBS, which includes: a centralized unit CU sends a first message to a distributed unit DU, the first message including an MBS identity; a CU receives a response message to the first message, the response message carrying information on discontinuous reception DRX of a broadcast service; CU sends a second message to DU, the second message carrying a broadcast configuration message.

Optionally, the first message is a service start request message; and the second message is a common radio resource control (RRC) transmission message.

Optionally, the second message also carries at least one of the following: cell identity; and MBS identity.

Optionally, the broadcast configuration message is included in a container.

Optionally, the method further includes: during the process of F1 establishment, CU receives DRX information reported by DU.

According to an aspect of the present disclosure, there is provided a method for transmission configuration of broadcast service which supports broadcasting MBS, which includes: a centralized unit CU sends a first message to a distributed unit DU, the first message including a list of surrounding cells; a CU receives a response message to the first message; CU sends a second message to DU, the second message carrying an updated list of surrounding cells.

Optionally, the first message is a service start request message; and the second message is an update message.

Optionally, the first message includes a list of neighboring cells which support broadcasting MBS broadcasted on the cell, and list of neighboring cells for one MBS service (List 1 and List 2).

Optionally, the second message includes List 2.

According to an aspect of the present disclosure, there is provided a method for transmission of broadcast service supporting multimedia broadcast multicast service MBS, which includes: a distributed unit DU receives a first message sent by a centralized unit CU, the first message including an MBS identity; DU sends to CU a response message to the first message, the response message carrying the information of the discontinuous reception DRX of a broadcast service; DU receives a second message sent by CU, the second message carrying a broadcast configuration message.

Optionally, the broadcast configuration message is included in a container.

Optionally, the method further includes: during the process of F1 establishment, DU reports DRX information to CU.

According to an aspect of the present disclosure, there is provided a method for transmission configuration of broadcast service which supports broadcasting MBS, which includes: a distributed unit DU receives a first message sent by a centralized unit CU, the first message includes a list of surrounding cells; DU sends to CU a response message to the first message; DU receives a second message sent by CU, the second message carrying an updated list of surrounding cells.

Optionally, the second message includes List 2.

According to an aspect of the present disclosure, there is provided a centralized unit including: a transceiver; and at least one processor connected to the transceiver and configured to execute the aforementioned method.

According to an aspect of the present disclosure, there is provided a distributed unit including: a transceiver; and at least one processor connected to the transceiver and configured to execute the aforementioned method.

According to various embodiments of the disclosure, procedures for broadcast service supporting MBS in a wireless communication system can be efficiently enhanced.

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

Fig. 2 is a schematic diagram of the initial overall architecture of 5G;

Fig. 3 is a schematic flowchart of the first embodiment of the present invention;

Fig. 4 is a schematic flowchart of the second embodiment of the present invention;

Fig. 5 is a schematic flowchart of the third embodiment of the present invention;

Fig. 6 is a block diagram of a node according to an embodiment of the present invention.

Before undertaking the DETAILED DESCRIPTION OF DRAWINGS below, 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,” as well as derivatives thereof, encompass both direct and indirect communication. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, means to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The term “controller” means any device, system, or part thereof that controls at least one operation. Such a controller may be implemented in hardware or 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. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

Moreover, various functions described below can 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 a portion 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 (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.

Figs. 1 to 6 discussed below and various embodiments for describing the principles of the present disclosure in this patent document are only for illustration and should not be interpreted as limiting the scope of the disclosure in any way. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any suitably arranged system or device.

Fig. 1 is an exemplary system architecture 100 of system architecture evolution (SAE). 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, which includes a macro base station (eNodeB/NodeB) that provides UE with interfaces to access the radio network. A mobility management entity (MME) 103 is responsible for managing mobility context, session context and security information of the UE. A serving gateway (SGW) 104 mainly provides functions of user plane, and the MME 103 and the SGW 104 may be in the same physical entity. A packet data network gateway (PGW) 105 is responsible for functions of charging, lawful interception, etc., and may be in the same physical entity as the SGW 104. A policy and charging rules function entity (PCRF) 106 provides quality of service (QoS) policies and charging criteria. A general packet radio service support node (SGSN) 108 is a network node device that provides routing for data transmission in a universal mobile telecommunications system (UMTS). A home subscriber server (HSS)109 is a home subsystem of the UE, and is responsible for protecting user information including a current location of the user equipment, an address of a serving node, user security information, and 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 the present disclosure.

User equipment (UE) 201 is a terminal device for receiving data. A next generation radio access network (NG-RAN, or RAN for short) 202 is a radio access network, which includes a base station (a gNB or an eNB connected to 5G core network 5GC, and the eNB connected to the 5GC is also called ng-gNB) that provides UE with interfaces to access the radio network. An access control and mobility management function entity (AMF) 203 is responsible for managing mobility context and security information of the UE. A user plane function entity (UPF) 204 mainly provides functions of user plane. A session management function entity SMF 205 is responsible for session management. A data network (DN) 206 includes, for example, services of operators, access of Internet and service of third parties.

The interface between AMF and NG-RAN is called NG-C interface, or NG interface or N2 interface. The interface between UPF and NG-RAN is called NG-U interface, or N3 interface, and the signaling between UE and AMF is called Non-Access Stratum Signaling (NAS), also called N1 interface. The interface between base stations is called Xn interface.

In the following embodiment, 5G system is taken as an example and the access network which is of a separate architecture is taken as an example, wherein the access network is divided into a centralized unit-control plane CU-CP, a centralized unit-user plane CU-UP and a distributed unit DU. For convenience of description, CU-CP and CU-UP are in the same entity. The method is also used in non-separation architecture, and is used in corresponding entities of other systems.

In order to make effective use of air interface resources, broadcast and multicast are used to provide service data to users, for the services with multiple receiving users receiving the same data. In addition to air interface resource sharing, the resources of access network and core network can also be used in a shared manner. This service is called multimedia broadcast multicast service, hereinafter referred to as MBS (Multicast and Broadcast Service).

MBS services are divided into two types. One is multicast service, for which, UE needs to join the multicast service first, 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 connected mode to accept the service. The other is broadcast service, for which, UE does not need to join a certain group, while the start information and configuration information of the service will be sent to the UE by broadcast, and all UEs in PMM connected modes and PMM idle modes can receive data.

When MBS is a broadcast service, the base station sends the data to the UE in a way of broadcast, and the UE in RRC idle and connected modes can receive the data of MBS service. In the case that the base station is of a separate architecture, CU can generate a common Radio Resource Control (RRC) message related to MBS, such as an MBS broadcast configuration message, which is sent to the UE over the air interface through a common channel, for example, sent to the UE through a multimedia broadcast multicast service control channel MCCH. The advantage of generating the MBS broadcast configuration message by CU is that CU can accurately know whether the data of a certain MBS is broadcasted in the adjacent cell, thereby indicating the correct information to the UE, so that the UE can select the cell that also broadcasts this MBS service when performing cell reselection, thus ensuring the continuity of service reception.

Embodiment 1 of Fig. 3 describes the generation of common RRC messages related to MBS by CU, such as MBS broadcast configuration messages. The detailed process is shown in Fig. 3.

At step 301, CU receives the MBS service start request message sent by the core network, and CU sends the service start request message to DU.

The service start request message contains the service identity of MBS, for example TMGI; the service area of MBS, for example a group of service area identities (e.g., SAI), or a group of cell identities (e.g., CGI), or a group of routing area identities (e.g., Tracking Area Identity, TAI), or Tracking area code (TAC); and containers from CU to DU. Information on the MBS radio bearer (MRB) to be established, for example, the identity of the radio bearer, the QoS requirements of the bearer, the information on the QoS flow corresponding to the radio bearer, the transport layer address and/or the tunnel identity of the uplink user plane, wherein the address is used to receive the status report information on the data of MBS.

The service start request may be directed to one DU or one cell. If it is directed to one cell, the service start request message may also contain an identity of the cell, indicating that the MBS service is transmitted on the cell. If it is transmitted on multiple cells, multiple messages of step 303 are sent.

Or the service start request message contains the identity list of the cells, and the identity list contains the identities of all cells which would transmit the MBS service.

At step 302, DU sends a service start response message to CU.

The service start response message contains the service identity of MBS; the information on the MRBs which are successfully established, at least including the identity of MRB; and the message also contains the transport layer address and/or the tunnel identity of the downlink user plane allocated by DU, wherein the address is used to receive the data of MBS. The message may also contain the information on the MRBs fails to be established, at least including the identity of the MRB. The message also contains containers from DU to CU. In the containers from DU to CU, they may contain configuration information of radio link control (RLC) of MRB, configuration information of Medium Access Control (MAC), and configuration information of the physical layer; and the containers also contain discrete reception DRX configuration information or DRX indication information (which is called DRX2) of point to multipoint transmission for the broadcast service. With the DRX configuration information or DRX indication information, through the indication information, which CU may know the DRX information used by this MBS service, wherein the DRX information is directed to this MBS service.

In the containers from DU to CU, they may also contain configuration information (which is called DRX1) of all DRX supported by DU for broadcast service, wherein the DRX is directed to point-to-multipoint transmission of broadcast service, instead of being directed to one MBS service. The DRX configuration information used by a certain MBS service may be one of DRX1s.

At step 303, CU sends a common RRC message transmission to DU.

The message name of this step may be others, for example, the request message may be update through the CU configuration. The message of step 303 is a common transmission message on F1, which contains the cell identity, the MBS identity or the indication of MBS common control channel, and the RRC message container. The RRC message container contains MBS broadcast configuration message. The MBS broadcast configuration message is transmitted on the common channel of the cell identified by the cell identity. The message may carry information on one cell or multiple cells.

The MBS broadcast configuration message contained in the RRC message container is generated by CU, and the MBS broadcast configuration message contains the DRX configuration of the MBS received by CU, that is, the DRX 1 and DRX2 obtained in step 302. The message also contains the list of neighboring cells. During the previous F1 establishment process, in the F1 establishment request message, DU may carry the indication information on whether MBS is supported, carry the cell identity on DU, and the service area identity (SAI) of MBS corresponding to the cell. From the F1 establishment process, CU may know whether a certain cell supports MBS service. According to the multiple F1 establishment request messages received, CU may determine which neighboring cells may support MBS broadcast service transmission in broadcast mode. Also, with reference to the service area of MBS service and/or the received service start response, CU may know which neighboring cells of the cell also provide MBS service broadcast by the cell. When generating the MBS broadcast configuration message of a certain cell, CU may generate a list of neighboring cells for MBS broadcast, which is called List 1. The List 1 is included in the MBS broadcast configuration message, and the List 1 contains the identities of the adjacent cells, indicating that these neighboring cells also support the MBS service broadcasted by the cell.

According to the response message of step 302, CU may know whether a certain MBS service has been successfully established on the cell. According to multiple service start response messages received, CU may generate a list of neighboring cells for MBS broadcast with respect to one MBS service, which is called List 2. The List 2 is also included in the MBS broadcast configuration message, and the List 2 contains the identities of a group of adjacent cells, which also provide the MBS service being broadcasted on the cell. The list of neighboring cells is directed to one MBS service. The List 2 may contain cell identities of the adjacent cells, or may contain indication information to indicate whether the corresponding cell in the List 1 transmits the MBS service in broadcast mode. For example, List 1 contains adjacent cell 1, cell 2 and cell 3. Among which, cell 1 and cell 3 are broadcasting MBS1, and the cell is also broadcasting MBS1. The List 2 is a three-bit string, in which the first bit and the third bit are set to "1" and the second bit is set to "0". By comparing List 1 and List 2, UE knows that cell 1 and cell 3 are also broadcasting the MBS service.

At step 305, DU broadcasts the MBS broadcast configuration message via air interface.

DU saves the MBS broadcast configuration message of the cell, and broadcasts the message on the common channel of the cell at an appropriate time. DU saves the configuration information of the MBS common control channel on the cell, and knows at what cycle and what time to start broadcasting the MBS broadcast configuration message. DU broadcasts over the air interface according to the configuration.

Embodiment 2 of Fig. 4 describes another embodiment of the generation of common RRC message related to MBS by CU. The detailed process is shown in Fig. 4.

At step 401, DU sends F1 establishment request message.

The message contains the information on the cell supported on DU, and the information on the cell contains the unique identity of the cell (CGI), the physical layer cell identity PCI, the operator identity and other information. It also contains the indication information on whether the cell supports MBS or whether DU supports MBS, the service area identity SAI of MBS corresponding to the cell, and the configuration of DRX that the cell may support for the point-to-multipoint transmission of broadcast service, which is called DRX1. The DRX is directed to point-to-multipoint transmission of broadcast service, instead of being directed to one MBS service. The DRX configuration information used by a certain MBS service may be one of the DRXs.

At step 402, CU sends F1 establishment response message.

The response contains the name of CU and the information on the cell that may be established.

At step 403, CU receives the MBS service start request message sent by the core network, and CU sends the service start request message to DU.

The service start request message contains the service identity of MBS, for example TMGI; the service area of MBS, for example a group of service area identities (e.g., SAI), or a group of cell identities (e.g., CGI), or a group of routing area identities (e.g., TAI or TAC); and containers from CU to DU. The message also contains information on the MBS radio bearer (MRB) to be established, for example, the identity of the radio bearer, the QoS requirements of the bearer, the information on the QoS flow corresponding to the radio bearer, the transport layer address and/or the tunnel identity of the uplink user plane, wherein the address is used to receive the status report information on the data of MBS.

The service start request may be directed to one DU or one cell. If it is directed to one cell, the service start request message may also contain an identity of the cell, indicating that the MBS service is transmitted on the cell. If it is transmitted on multiple cells, multiple messages of step 403 are sent.

At step 404, DU sends a service start response message to CU.

The service start response message contains the service identity of MBS; the information on the MRBs which are successfully established, at least including the identity of MRB; and the message also contains the transport layer address and/or the tunnel identity of the downlink user plane allocated by DU, wherein the address is used to receive the data of MBS. The message may also contain the information on the MRBs fails to be established, at least including the identity of the MRB. The message also contains containers from DU to CU.

In the containers from DU to CU, they may contain configuration information of RLC of MRB, configuration information of MAC, and configuration information of the physical layer; and the containers also contain discrete reception DRX configuration information or DRX indication information (which is called DRX2) of point to multipoint transmission for the broadcast service. The DRX configuration information or DRX indication information is directed to this MBS service. The DRX configuration information used by a certain MBS service may be one of DRX1s.

The MRB successfully established above and containers from DU to CU are all directed to one cell, and the service start response message may also contain the cell identity of the cell.

If the response message contains response messages of multiple cells, the response messages of multiple cells are respectively transmitted through a list.

At step 405, CU sends a common RRC message transmission to DU.

The message name of this step may be others, for example, the request message may be update through the CU configuration. The message of step 405 is a common transmission message on F1, which contains the cell identity, the MBS identity or the indication of MBS common control channel, and the RRC message container. The RRC message container contains MBS broadcast configuration message. The MBS broadcast configuration message is transmitted on the common channel of the cell identified by the cell identity. The message may carry information on one cell or multiple cells.

The MBS broadcast configuration message contained in the RRC message container is generated by CU, and the MBS broadcast configuration message contains the DRX configuration of the MBS received by CU, that is, the DRX 1 and DRX2 obtained in previous steps. The message also contains the list of neighboring cells. During the F1 establishment process, in the F1 establishment request message, DU may carry the indication information on whether MBS is supported, carry the cell identity on DU, and the service area identity (SAI) of MBS corresponding to the cell. From the F1 establishment process, CU may know whether a certain cell supports MBS service. When generating the MBS broadcast configuration message of a certain cell, CU may also refer to the service area of MBS service, CU may know which neighboring cells of the cell also provide MBS service broadcast by the cell, and CU may generate a list of neighboring cells for MBS broadcast, which is called List 1. The List 1 is included in the MBS broadcast configuration message, and the List 1 contains the identities of the adjacent cells, indicating that these neighboring cells also support the MBS service broadcasted by the cell. The List 1 is not directed to a certain MBS service.

According to the response message of step 404, CU may know whether a certain MBS service has been successfully established on the cell. According to multiple service start response messages received, CU may generate a list of neighboring cells for MBS broadcast with respect to one MBS service, which is called List 2. The List 2 is also included in the MBS broadcast configuration message, and the List 2 contains the identities of a group of adjacent cells, which also provide the MBS service being broadcasted on the cell. The list of neighboring cells is directed to one MBS service. The List 2 may contain cell identities of the adjacent cells, or may contain indication information to indicate whether the corresponding cell in the List 1 transmits the MBS service in broadcast mode. For example, List 1 contains adjacent cell 1, cell 2 and cell 3. Among which, cell 1 and cell 3 are broadcasting MBS1, and the cell is also broadcasting MBS1. The List 2 is a three-bit string, in which the first bit and the third bit are set to "1" and the second bit is set to "0". By comparing List 1 and List 2, DU knows that cell 1 and cell 3 are also broadcasting the MBS service.

The message of step 405 may also transmit the common RRC messages of multiple cells, which is implemented by a list.

At step 406, DU broadcasts the MBS broadcast configuration message via air interface.

Embodiment 3 of Fig. 5 describes the generation of common RRC messages related to MBS by DU, e.g., MBS broadcast configuration messages. The generation of MBS broadcast configuration message by DU has the advantage of reducing signaling interaction. The detailed process is shown in Fig. 5.

At step 501, CU receives the MBS service start request message sent by the core network, and CU sends the service start request message to DU.

The message contains the service identity of MBS, for example TMGI; the service area of MBS, for example a group of service area identities (e.g., SAI), or a group of cell identities (e.g., CGI), or a group of routing area identities (e.g., TAI or TAC); and containers from CU to DU. The message also contains information on the MBS radio bearer (MRB) to be established, for example, the identity of the radio bearer, the QoS requirements of the bearer, the information on the QoS flow corresponding to the radio bearer, the transport layer address and/or the tunnel identity of the uplink user plane, wherein the address is used to receive the status report information on the data of MBS.

The service start request may be directed to one DU or one cell. If it is directed to one cell, the message may also contain an identity of the cell, indicating that the MBS service is to be broadcast on this cell. If it is required to broadcast on multiple cells under this DU, multiple messages will be sent, or information of multiple cells are included in one message with a list corresponds to the information on multiple cells, wherein the elements of each list correspond to the related information on one cell.

In the containers from CU to DU, they may contain a list (List 1) of neighboring cell. During the previous F1 establishment process, in the F1 establishment request message, DU may carry the indication information of whether MBS is supported, carry the cell identity and the service area identity SAI of MBS corresponding to the cell. From the F1 establishment process, CU may know whether a certain cell supports MBS service. According to the multiple F1 establishment request messages received or the service area of MBS included in the received service start request message, CU may determine which neighboring cells may support MBS broadcast service transmission in broadcast mode. CU may generate a list of neighboring cells for MBS broadcast, which is called List 1, and the list contains the identity of adjacent cells, indicating that these neighboring cells are also broadcasting the MBS service being broadcasted by the cell. Containers from CU to DU may contain List1. List 1 is not directed to a certain MBS service. Since the List 1 is not directed to one MBS service, it can also be transmitted to DU in the F1 establishment response message or the F1 configuration update request message. However, the disadvantage of early transmission is that it affects the F1 establishment and update process before MBS starts.

In the containers from CU DU, it may also contain a list (List 2) of neighboring cells. List 1 and List 2 can be in the same container or in different containers. For a certain cell, according to the MBS identity and the service area of MBS contained in a certain MBS service start request message, CU may know which cell this MBS service is broadcast on, and CU may generate a list of neighboring cell for MSB with respect to this MBS service, which is called List 2. The list of neighboring cell contains the identities of a group of adjacent cells, and these cells also provide the MBS service being broadcasted on the cell. The list of neighboring cells is directed to one MBS service. The List 2 may contain cell identities of the adjacent cells, or may contain indication information to indicate whether the corresponding cell in the List 1 transmits the MBS service in broadcast mode. For example, List 1 contains adjacent cell 1, cell 2 and cell 3. Among which, cell 1 and cell 3 are broadcasting MBS1, and the cell is also broadcasting MBS1. The List 2 is a three-bit string, in which the first bit and the third bit are set to "1" and the second bit is set to "0". By comparing List 1 and List 2, UE knows that cell 1 and cell 3 are also broadcasting the MBS service.

The List 2 can also be carried by the message of step 503.

The List 1 and/or the List 2 can also be directly carried in the message of 501 without being carried through the container from CU to DU.

According to the message of step 501, the container from CU to DU, and the information saved by DU, DU may generate MBS broadcast configuration message.

At step 502, DU sends a service start response message to CU.

The service start response message contains the service identity of MBS; the information on the MRBs which are successfully established, at least including the identity of MRB. The message may also contain the information on the MRBs fails to be established, at least including the identity of the MRB.

At step 503, after receiving the service start response from DU, CU may know whether the cell on DU has established the transmission channel of MBS, and know exactly whether the surrounding cells are broadcasting this service. CU may send an update message, which carries the MBS identity, List 2. As described in step 501, if List 2 is included in the message of step 501, upon receiving this message, DU needs to replace the List 2 received in step 501 and update the content of the MBS broadcast configuration message. According to another implementation of the invention, if step 501 contains List 2, in some cases, for example, that all surrounding cells have successfully established MBS transmission information, step 503 may not be sent. If DU does not receive the update message of step 503 before sending the MBS broadcast configuration message over the air interface, DU will use the List 2 received in step 501 to generate the MBS broadcast configuration message.

At step 504, DU broadcasts the MBS broadcast configuration message via air interface.

So far, the method for transmission of broadcast service supporting MBS of the present invention has been completed, which can support reducing signaling interaction under the separated architecture, provide accurate broadcast information for UE, and enable UE to select attached cell by using the correct broadcast information when selecting service cell, thus reducing the interruption of MBS data.

FIG. 6 is a block diagram of a node according to an example embodiment of the present disclosure. Here, the structure and function of a node are explained by taking it as an example, but it should be understood that the structure and function shown can also be applied to a base station (or a centralized unit of a base station, or a control plane part of a centralized unit of a base station, or a user plane part of a centralized unit of a base station, or a distributed unit of a base station, etc.).

Referring to fig. 6, the node 600 includes a transceiver 610, a controller 620 and a memory 630. Under the control of the controller 620 (which can be implemented as one or more processors), the node 600 (including the transceiver 610 and the memory 630) is configured to perform the operations of the node in the flow shown in Figs. 6-10 or described above. Although the transceiver 610, the controller 620 and the memory 630 are shown as separate entities, they can be implemented as a single entity, such as a single chip. The transceiver 610, the controller 620 and the memory 630 may be electrically connected or coupled to each other. Transceiver 610 may send and receive signals to and from other network entities, e.g., another node and/or UE. In one embodiment, the transceiver 610 may be omitted. In this case, the controller 620 may be configured to execute instructions (including computer programs) stored in the memory 630 to control the overall operation of the node 600, so as to realize the operation of the node in the flow shown in Figs. 3-5 or described above.

The methods according to the embodiments described in the claims or the detailed description of the present disclosure may be implemented in hardware, software, or a combination of hardware and software.

When the electrical structures and methods are implemented in software, a computer-readable recording medium having one or more programs (software modules) recorded thereon may be provided. The one or more programs recorded on the computer-readable recording medium are configured to be executable by one or more processors in an electronic device. The one or more programs include instructions to execute the methods according to the embodiments described in the claims or the detailed description of the present disclosure.

In the afore-described embodiments of the present disclosure, elements included in the present disclosure are expressed in a singular or plural form according to the embodiments. However, the singular or plural form is appropriately selected for convenience of explanation and the present disclosure is not limited thereto. As such, an element expressed in a plural form may also be configured as a single element, and an element expressed in a singular form may also be configured as plural elements.

Those skilled in the art can realize that the present disclosure can be implemented in other specific forms without changing the technical idea or basic characteristics of the present disclosure. Therefore, it should be understood that the above-mentioned embodiments are only examples and are not limited. The scope of the present disclosure is defined by the appended claims, rather than the detailed description. Therefore, it should be understood that all modifications or changes derived from the meaning and scope of the appended claims and their equivalents are within the scope of this disclosure.

In the above embodiments of the present disclosure, all operations and messages may be selectively performed or omitted. In addition, the operations in each embodiment need not be executed sequentially, and the order of the operations can be changed. Messages do not need to be delivered in sequence, and the delivery order of messages may change. Each operation and each message transmission can be performed independently.

Although the invention has been shown and described with reference to various embodiments of the present disclosure, it will be understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

A method performed by a centralized unit (CU) of a base station in a wireless communication system, the method comprising:

receiving, from a distributed unit (DU) of the base station, a F1 setup request message including served cell information indicating an service area identity for multimedia broadcast multicast service (MBS); and

transmitting, to the DU, a F1 setup response message in response to the F1 setup request message.
The method of claim 1,

wherein the F1 setup response message includes information indicating a list of at least one neighboring cell which provides MBS broadcast service.
The method of claim 1, further comprising:

transmitting, to the DU of the base station, a first message including information indicating a list of at least one neighboring cell which provides MBS broadcast service and information on an MBS service area; and

receiving, from the DU of the base station, a second message in response to the first message, the second message including information indicating an identity for a MBS radio bearer (MRB) failed to be setup.
The method of claim 3, further comprising:

transmitting, to the DU of the base station, a third message including information for modifying the list of at least one neighboring cell.
The method performed by a distributed unit (DU) of a base station in a wireless communication system, the method comprising:

transmitting, to a centralized unit (CU) of the base station, a F1 setup request message including served cell information indicating an service area identity for multimedia broadcast multicast service (MBS); and

receiving, from the CU of the base station, a F1 setup response message in response to the F1 setup request message,

wherein the F1 setup response message includes information indicating a list of at least one neighboring cell which provides MBS broadcast service.
The method of claim 1, further comprising:

receiving, from the CU of the base station, a first message including information indicating a list of at least one neighboring cell which provides MBS broadcast service and information on an MBS service area; and

transmitting, to the CU of the base station, a second message in response to the first message, the second message including information indicating an identity for a MBS radio bearer (MRB) failed to be setup.
The method of claim 6, further comprising:

receiving, from the CU of the base station, a third message including information for modifying the list of at least one neighboring cell.
A centralized unit (CU) of a base station in a wireless communication system, the CU comprising:

a controller; and

a transceiver coupled with the controller and configured to:

receive, from a distributed unit (DU) of the base station, a F1 setup request message including served cell information indicating an service area identity for multimedia broadcast multicast service (MBS), and

transmit, to the DU, a F1 setup response message in response to the F1 setup request message.
The CU of claim 8,

wherein the F1 setup response message includes information indicating a list of at least one neighboring cell which provides MBS broadcast service.
The CU of claim 8, wherein the controller is further configured to:

transmit, to the DU of the base station, a first message including information indicating a list of at least one neighboring cell which provides MBS broadcast service and information on an MBS service area, and

receive, from the DU of the base station, a second message in response to the first message, the second message including information indicating an MRB identity for a MBS radio bearer (MRB) failed to be setup.
The CU of claim 10, wherein the controller is further configured to:

transmit, to the DU of the base station, a third message including information for modifying the list of at least one neighboring cell.
The distributed unit (DU) of a base station in a wireless communication system, the DU comprising:

a controller; and

a transceiver coupled with the controller and configured to:

transmit, to a centralized unit (CU) of the base station, a F1 setup request message including served cell information indicating an service area identity for multimedia broadcast multicast service (MBS), and

receive, from the CU of the base station, a F1 setup response message in response to the F1 setup request message.
The DU of claim 12,

wherein the F1 setup response message includes information indicating a list of at least one neighboring cell which provides MBS broadcast service.
The DU of claim 12, wherein the controller is further configured to:

receive, from the CU of the base station, a first message including information indicating a list of at least one neighboring cell which provides MBS broadcast service and information on an MBS service area, and

transmit, to the CU of the base station, a second message in response to the first message, the second message including information indicating an identity for a MBS radio bearer (MRB) failed to be setup.
The DU of claim 12, wherein the controller is further configured to:

receive, from the CU of the base station, a third message including information for modifying the list of at least one neighboring cell.