Communication control method, user device, processor, network device, mobile communication system, and program

Abstract

To provide a communication control method and a base station for achieving an improved multicast broadcast service (MBS).SOLUTION: A communication control method is used in a mobile communication system for providing an MBS from a base station gNB to user equipment UE. The communication control method includes: broadcasting, by the base station, an MBS system information block; and transmitting, by the base station, scheduling information of an MBS traffic channel on an MBS control channel, wherein the MBS system information block includes a search space identifier for the user equipment to receive the MBS control channel, and the search space identifier indicates a search space that is a resource range to be decoded by the user equipment in a physical downlink control channel associated with the MBS control channel.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present disclosure relates to a communication control method and a base station used in a mobile communication system.

Background Art

[0002] In recent years, the fifth-generation (5G) mobile communication system has attracted attention. NR (New Radio), which is a radio access technology (RAT) of the 5G system, has characteristics such as high speed, large capacity, high reliability, and low latency compared to LTE (Long Term Evolution), which is a fourth-generation radio access technology.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

[0004] The communication control method according to the first aspect is a communication control method used in a mobile communication system that provides a multicast / broadcast service (MBS) from a base station to a user equipment, wherein the base station broadcasts an MBS system information block, and the base station transmits scheduling information of an MBS traffic channel on an MBS control channel, the MBS system information block includes a search space identifier for the user equipment to receive the MBS control channel, and the search space identifier indicates a search space that is a resource range to be decoded by the user equipment in a physical downlink control channel associated with the MBS control channel.

[0005] A second aspect of the communication control method is a communication control method used in a mobile communication system that provides multicast broadcast service (MBS) from a base station to a user device, comprising: broadcasting a predetermined system information block used for scheduling MBS system information blocks; broadcasting the MBS system information block; and transmitting scheduling information for MBS traffic channels on an MBS control channel, wherein the predetermined system information block includes a search space identifier for the user device to receive the MBS control channel, and the search space identifier indicates a search space which is a resource range to be decoded by the user device in a physical downlink control channel associated with the MBS control channel.

[0006] A third aspect of the communication control method is a communication control method used in a mobile communication system that provides multicast broadcast service (MBS) from a base station to user equipment, comprising: the base station broadcasting an MBS system information block; and the base station transmitting scheduling information for an MBS traffic channel and a search space identifier for the user equipment to receive the MBS traffic channel via an MBS control channel, wherein the search space identifier indicates a search space which is the resource range to be decoded by the user equipment in a physical downlink control channel associated with the MBS traffic channel.

[0007] A fourth aspect of the communication control method is a communication control method used in a mobile communication system that provides multicast broadcast service (MBS) from a base station to a user device, wherein the base station managing the cell transmits a notification message in the first cell to the user device regarding MBS transmission in an adjacent cell different from the cell, the notification message includes a search space identifier for the user device to receive a predetermined channel provided in an adjacent cell different from the cell, the search space identifier includes a search space identifier indicating a search space which is a resource range to be decoded by the user device in a physical downlink control channel associated with the predetermined channel provided in the adjacent cell, and the predetermined channel is an MBS control channel or MBS traffic channel provided in the adjacent cell.

[0008] A fifth aspect of the communication control method is a communication control method used in a mobile communication system that provides multicast broadcast service (MBS) from a base station to user equipment, comprising: the base station managing a cell broadcasting an MBS system information block for the MBS; and the base station transmitting a plurality of MBS control channels in the cell, wherein the MBS system information block includes a change notification RNTI (Radio Network Temporary Identifier) ​​for each of the plurality of MBS control channels, and the change notification RNTI is an RNTI used by the user equipment to receive a change notification indicating that the content of the corresponding MBS control channel has been changed.

[0009] The base station according to the sixth embodiment includes a processor that performs any of the communication control methods according to the first to fifth embodiments. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram shows the configuration of a mobile communication system according to an embodiment. [Figure 2]This diagram shows the configuration of the UE (User Equipment) according to the embodiment. [Figure 3] This diagram shows the configuration of the gNB (base station) according to the embodiment. [Figure 4] This diagram shows the protocol stack configuration of the user plane wireless interface that handles data. [Figure 5] This diagram shows the protocol stack configuration of the wireless interface of the control plane that handles signaling (control signals). [Figure 6] This figure shows the correspondence between the logical channel and the transport channel of the downlink according to the embodiment. [Figure 7] This figure shows the method for distributing MBS data according to an embodiment. [Figure 8] This diagram shows the correspondence between channels according to the embodiment. [Figure 9] This figure shows a first example of operation of the mobile communication system according to the embodiment. [Figure 10] This figure shows a second example of operation of the mobile communication system according to the embodiment. [Figure 11] This figure shows a third example of operation of the mobile communication system according to the embodiment. [Figure 12] This figure shows an example of the operating environment in the fourth operational example of the mobile communication system according to the embodiment. [Figure 13] This figure shows a fourth example of operation of the mobile communication system according to the embodiment. [Figure 14] This figure shows a fifth example of operation of the mobile communication system according to the embodiment. [Modes for carrying out the invention]

[0011] The introduction of multicast broadcast services into 5G systems (NR) is being considered. It is desirable that NR multicast broadcast services provide improved service compared to LTE multicast broadcast services.

[0012] Therefore, an object of the present disclosure is to provide a communication control method for realizing an improved multicast / broadcast service.

[0013] A mobile communication system according to an embodiment will be described while referring to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0014] (Configuration of Mobile Communication System) First, the configuration of the mobile communication system according to the embodiment will be described. FIG. 1 is a diagram showing the configuration of the mobile communication system according to the embodiment. This mobile communication system complies with the 5th generation system (5GS) of the 3GPP standard. Hereinafter, the 5GS will be described as an example, but the LTE (Long Term Evolution) system may be at least partially applied to the mobile communication system.

[0015] As shown in FIG. 1, the mobile communication system includes a user equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20.

[0016] The UE 100 is a movable wireless communication device. The UE 100 may be any device as long as it is a device used by a user. For example, the UE 100 may be a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided in the sensor, a vehicle or a device provided in the vehicle (Vehicle UE), and / or an aircraft or a device provided in the aircraft (Aerial UE).

[0017] NG-RAN 10 includes base stations (referred to as "gNB" in the 5G system) 200. The gNBs 200 are interconnected via the Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with the UE 100 that has established a connection with its cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, etc. "Cell" is used as a term indicating the smallest unit of a wireless communication area. "Cell" is also used as a term indicating a function or resource for performing wireless communication with the UE 100. One cell belongs to one carrier frequency.

[0018] Note that the gNB can also be connected to the EPC (Evolved Packet Core), which is the core network of LTE. The base station of LTE can also be connected to the 5GC. The base station of LTE and the gNB can also be connected via an interface between base stations.

[0019] The 5GC 20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE 100, etc. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF performs transfer control of data. The AMF and the UPF are connected to the gNB 200 via the NG interface, which is an interface between the base station and the core network.

[0020] FIG. 2 is a diagram showing the configuration of the UE 100 (user equipment) according to the embodiment.

[0021] As shown in FIG. 2, the UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130.

[0022] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130.

[0023] The transmitting unit 120 performs various types of transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 130 into a wireless signal and transmits it from the antenna.

[0024] The control unit 130 performs various controls on the UE100. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing.

[0025] Figure 3 shows the configuration of the gNB200 (base station) according to this embodiment.

[0026] As shown in Figure 3, the gNB200 comprises a transmitting unit 210, a receiving unit 220, a control unit 230, and a backhaul communication unit 240.

[0027] The transmitting unit 210 performs various types of transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[0028] The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 230.

[0029] The control unit 230 performs various controls in the gNB200. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing.

[0030] The backhaul communication unit 240 is connected to an adjacent base station via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF300 via a base station-core network interface. The gNB may consist of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally separated), and the two units may be connected via an F1 interface.

[0031] Figure 4 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0032] As shown in Figure 4, the user plane radio interface protocol has a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an SDAP (Service Data Adaptation Protocol) layer.

[0033] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the UE100's PHY layer and the gNB200's PHY layer via a physical channel.

[0034] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of the UE100 and the MAC layer of the gNB200 via the transport channel. The MAC layer of the gNB200 includes a scheduler. The scheduler determines the transport format for the up and down links (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE100.

[0035] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the UE100's RLC layer and the gNB200's RLC layer via a logical channel.

[0036] The PDCP layer performs header compression / decompression, and encryption / decryption.

[0037] The SDAP layer maps IP flows, which are the units under which the core network performs QoS (Quality of Service) control, to wireless bearers, which are the units under which the AS (Access Stratum) performs QoS control. Note that if the RAN is connected to the EPC, the SDAP is not required.

[0038] Figure 5 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0039] As shown in Figure 5, the protocol stack of the control plane's wireless interface has an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer instead of the SDAP layer shown in Figure 4.

[0040] RRC signaling for various settings is transmitted between the RRC layer of the UE100 and the RRC layer of the gNB200. The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. If there is a connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC connected state. If there is no connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC idle state. If the connection between the RRC of the UE100 and the RRC of the gNB200 is suspended, the UE100 is in the RRC inactive state.

[0041] The NAS layer, located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the UE100's NAS layer and the AMF300's NAS layer.

[0042] In addition to the wireless interface protocol, the UE100 also has an application layer and other components.

[0043] (MBS) Next, an MBS according to one embodiment will be described. MBS is a service that enables broadcast or multicast, that is, point-to-multipoint (PTM) data transmission from NG-RAN10 to UE100. MBS may also be called MBMS (Multimedia Broadcast and Multicast Service). Use cases (service types) of MBS include public security communications, mission-critical communications, V2X (Vehicle to Everything) communications, IPv4 or IPv6 multicast distribution, IPTV (Internet protocol television), group communications, and software distribution.

[0044] There are two types of MBS transmission methods in LTE: MBSFN (Multicast Broadcast Single Frequency Network) transmission and SC-PTM (Single Cell Point To Multipoint) transmission. Figure 6 shows the correspondence between the logical channel and the transport channel of a downlink according to one embodiment.

[0045] As shown in Figure 6, the logical channels used for MBSFN transmission are MTCH (Multicast Traffic Channel) and MCCH (Multicast Control Channel), and the transport channel used for MBSFN transmission is MCH (Multicast Channel). MBSFN transmission is primarily designed for multi-cell transmission, and in an MBSFN area consisting of multiple cells, each cell synchronously transmits the same signal (same data) using the same MBSFN subframe.

[0046] The logical channels used for SC-PTM transmission are SC-MTCH (Single Cell Multicast Traffic Channel) and SC-MCCH (Single Cell Multicast Control Channel), and the transport channel used for SC-PTM transmission is DL-SCH (Downlink Shared Channel). SC-PTM transmission is primarily designed for single-cell transmission, performing broadcast or multicast data transmission on a cell-by-cell basis. The physical channels used for SC-PTM transmission are PDCCH (Physical Downlink Control Channel) and PDSCH (Physical Downlink Shared Channel), enabling dynamic resource allocation.

[0047] The following primarily describes an example of MBS being provided using a method similar to the SC-PTM transmission method, but MBS may also be provided using the MBSFN transmission method. Furthermore, the description will primarily focus on an example of MBS being provided via multicast. Therefore, MBS may be interpreted as multicast. However, MBS may also be provided via broadcast.

[0048] Furthermore, MBS data refers to data provided by MBS, the MBS control channel refers to MCCH or SC-MCCH, and the MBS traffic channel refers to MTCH or SC-MTCH. However, MBS data may also be transmitted by unicast. MBS data may also be called MBS packets or MBS traffic.

[0049] The MBS control channel is a one-to-many (PTM) downlink channel used to transmit MBS control information from the gNB200 to the UE100. The MBS control channel is mapped to DL-SCH (Downlink Shared Channel), which is a type of transport channel.

[0050] The MBS traffic channel is a one-to-many (PTM) downlink channel used to transmit MBS data from the gNB200 to the UE100. The MBS traffic channel is a type of logical channel and is mapped to the DL-SCH. There is a one-to-one correspondence between the MBS traffic channel and the MBS session.

[0051] DL-SCH is mapped to PDSCH (Physical Downlink Shared Channel), a type of physical channel. PDSCH is scheduled by DCI (Downlink Control Information) carried by PDCCH (Physical Downlink Control Channel), another type of physical channel.

[0052] The network can provide different MBS services for each MBS session. An MBS session is identified by at least one of the following: TMGI (Temporary Mobile Group Identity) and a session identifier, and at least one of these identifiers is called the MBS session identifier. Such an MBS session identifier may also be called an MBS service identifier or a multicast group identifier.

[0053] Figure 7 shows a method for distributing MBS data according to one embodiment.

[0054] As shown in Figure 7, MBS data (MBS Traffic) is delivered from a single data source (application service provider) to multiple UEs. The 5G core network, 5G CN (5GC)20, receives MBS data from the application service provider, creates copies of the MBS data (replication), and delivers them.

[0055] From the perspective of 5GC20, two delivery methods are possible: Shared MBS Traffic delivery and Individual MBS Traffic delivery.

[0056] In shared MBS data distribution, a connection is established between NG-RAN10, a 5G wireless access network (5G RAN), and 5GC20, and MBS data is distributed from 5GC20 to NG-RAN10. Hereafter, this connection (tunnel) will be referred to as the "MBS connection".

[0057] An MBS connection may also be called a Shared MBS Traffic Delivery connection or a shared transport. The MBS connection terminates at NG-RAN10 (i.e., gNB200). The MBS connection may have a one-to-one correspondence with an MBS session.

[0058] The gNB200 selects either PTP (Point-to-Point: unicast) or PTM (Point-to-Multipoint: multicast or broadcast) as its own decision and sends MBS data to the UE100 using the selected transmission method.

[0059] On the other hand, in individual MBS data distribution, a unicast session is established between NG-RAN10 and UE100, and MBS data is individually distributed from 5GC20 to UE100. Such a unicast may also be called a PDU session. The unicast (PDU session) terminates at UE100.

[0060] (Channel correspondence) Next, the channel correspondence according to one embodiment will be described.

[0061] Figure 8 is a diagram showing the correspondence between channels according to one embodiment. Each channel shown in Figure 8 is provided in one cell. Although Figure 8 illustrates an example in which multiple MBS control channels are provided in one cell, only one MBS control channel may be provided in one cell.

[0062] Furthermore, while each block shown in Figure 8 represents one channel, the "PDCCH" notation in each block means that the radio resources (PDSCH) for that channel are allocated by the PDCCH at the physical layer. In other words, it is assumed that the broadcast control channel, MBS control channel, and MBS traffic channel are all mapped to the DL-SCH.

[0063] Firstly, the gNB200 broadcasts SIB type 1 on the broadcast control channel. SIB type 1 includes scheduling information for the MBS system information block (MBS SIB) (hereinafter referred to as "MBS SIB scheduling information"). MBS SIB scheduling information is information for scheduling the messages that carry the MBS SIB (SI messages, described later). The MBS SIB is a system information block for MBS and is a type of OSI (Other System Information), described later.

[0064] Secondly, the gNB200 broadcasts an MBS SIB on the broadcast control channel according to the scheduling of SIB type 1. The MBS SIB includes information indicating the scheduling of the MBS control channel (hereinafter referred to as "MBS control channel scheduling information"). The MBS SIB is transmitted at a period scheduled by a predetermined SIB (e.g., SIB type 1). The MBS control channel scheduling information is information for identifying candidate time positions where the MBS control channel may be transmitted. Such candidate time positions may be called MBS control channel transmission windows. Such candidate time positions may consist of a predetermined number of time units arranged periodically. The time unit may be a slot. Alternatively, the time unit may be a subframe. The MBS control channel scheduling information includes the repetition period (repeated transmission period), Offset (offset value of the SFN performing the scheduling), Start point (scheduling start subframe / slot), Duration (scheduling period from the Start point), and / or Modification period (modification period), etc.

[0065] Furthermore, the gNB200 may provide multiple MBS control channels in the cells it manages. For example, each MBS control channel may be associated with a different quality of service requirement (or service category). This makes it possible to configure MBS control channels optimized according to the quality of service requirements. In this case, the MBS SIB may schedule each of the multiple MBS control channels (MCCH#1 and MCCH#2). Different scheduling can be applied to each MBS control channel. The MBS control channels are transmitted at the intervals indicated by the MBS SIB.

[0066] Thirdly, the gNB200 broadcasts MBS traffic channel scheduling information on the MBS control channel according to the MBS control channel scheduling information. The MBS traffic channel scheduling information is information for identifying candidate time positions where the MBS traffic channel may be transmitted. Such candidate time positions may consist of a predetermined number of time units that are arranged periodically. The time units may be slots. Alternatively, the time units may be subframes. The MBS traffic channel scheduling information includes an On duration timer, a DRX inactivity timer, a Scheduling period (transmission cycle), and / or a Start offset (transmission SFN offset value), etc.

[0067] Figure 8 shows an example where MCCH#1 refers to one MBS traffic channel (MTCH#1) and MCCH#2 refers to two MBS traffic channels (MTCH#2 and MTCH#3). MTCH#1 is an MBS traffic channel that transmits MBS data for delay-sensitive MBS services. MTCH#2 and MTCH#3 are MBS traffic channels that transmit MBS data for typical MBS services.

[0068] Fourth, the gNB200 transmits MBS data on the MBS traffic channel (e.g., PTM transmission) according to the MBS traffic channel scheduling information.

[0069] (Search space) Next, a search space according to one embodiment will be described.

[0070] The 5G / NR specification aims to reduce the number of blind decoding operations performed by the UE100 by limiting the resource range targeted for blind decoding by the PDCCH in the UE100. Such a resource range is a time-frequency resource range, consisting of multiple resource blocks in the frequency direction and multiple symbols in the time direction. Such a resource range is called a search space. In one embodiment, the gNB200 provides multiple search spaces within its own cell. The gNB200 provides search space configuration information for setting up multiple search spaces within its own cell using SIB type 1 or RRC Reconfiguration messages. This allows for dynamic changes to the settings of each search space, enabling resource optimization.

[0071] Search space configuration information includes, for each of multiple search spaces, a set of search space identifiers that identify the search space and search space parameters that configure the search space. The search space parameters identify multiple resource blocks and multiple symbols that constitute the search space. Examples of search space parameters include ControlResourceSetID, monitoringSlotPeriodicityAndOffset, and / or monitoringSymbolsWithinSlot. ControlResourceSetID is a parameter used to identify resource blocks, while monitoringSlotPeriodicityAndOffset and monitoringSymbolsWithinSlot are parameters used to identify symbols.

[0072] In one embodiment, gNB200 sets up a special search space (hereinafter referred to as the "specific search space") in its own cell that is different from the multiple search spaces described above. The specific search space is a search space in which UE100 can identify multiple resource blocks and multiple symbols that constitute the specific search space according to pre-set rules, i.e., scheduling and resource range. UE100 can identify the scheduling and resource range of the specific search space even without search space setting information from gNB200 for that specific search space.

[0073] The gNB200 assigns the search space identifier "0" to a specific search space. This specific search space is sometimes referred to as search space zero. To distinguish this specific search space from the aforementioned multiple search spaces, the gNB200 does not assign the search space identifier "0" to the aforementioned multiple search spaces. For example, a search space includes the specific search space "0" and the other search spaces "1" through "4".

[0074] In one embodiment, the gNB200 associates different search spaces with different types of downlink messages transmitted in a cell of the gNB200. Examples of downlink message types include system information messages (SI messages) and paging messages. SI messages are used to carry system information blocks other than SIB type 1. These system information blocks are called OSI (Other System Information). For example, the gNB200 associates an SI message with the search space identified by the search space identifier "1" in the search space configuration information (search space #1), and a paging message with the search space identified by the search space identifier "2" in the search space configuration information (search space #2), and transmits information indicating this association in SIB type 1. Hereinafter, the search space associated with an SI message carrying OSI will be referred to as the "OSI search space."

[0075] (First example of operation of a mobile communication system) Next, a first example of operation of the mobile communication system 1 according to one embodiment will be described.

[0076] In this first operational example, we assume that a search space is assigned to the MBS control channel. In this case, the MBS control channel is thought to be assigned either a specific search space (e.g., search space "0") or another search space (e.g., search spaces "1" through "4"). Here, the scheduling of the MBS control channel differs depending on whether search space "0" is used or another search space (e.g., search space "1"). Note that the MBS control channel may be assigned a search space different from the OSI search space. In this case, even if UE100 knows the OSI search space, it cannot receive the MBS control channel.

[0077] Under these circumstances, UE100 needs to identify the search space associated with the MBS control channel in order to receive the MBS control channel. However, UE100 cannot determine which search space it should target for blind decoding in order to receive the MBS control channel.

[0078] In this first operational example, the gNB200 broadcasts an MBS SIB, transmitting scheduling information for the MBS traffic channel over the MBS control channel. The MBS SIB includes a search space identifier for the UE100 to receive the MBS control channel. The search space identifier indicates the search space, which is the resource range that the UE100 will decode in the physical downlink control channel associated with the MBS control channel. This allows the UE100 to determine which search space to target for blind decoding in order to receive the MBS control channel.

[0079] In this first operational example, if multiple MBS control channels are provided within a single cell of the gNB200, the MBS SIB may include a search space identifier for each of the multiple MBS control channels. This allows the UE100 to determine which search space to target for blind decoding in order to receive each MBS control channel, even when multiple MBS control channels are provided within a single cell of the gNB200.

[0080] In this first operational example, if the MBS control channel is not associated with a specific search space, the gNB200 may broadcast an MBS SIB that further includes MBS control channel scheduling information indicating the scheduling of the MBS control channel. As described above, a specific search space is a search space in which the UE100 can identify the scheduling and resource range of the MBS control channel according to pre-configured rules. This allows the UE100 to understand the scheduling of the MBS control channel even if the MBS control channel is not associated with a specific search space.

[0081] Figure 9 shows a first example of operation of the mobile communication system 1.

[0082] As shown in Figure 9, in step S101, gNB200 broadcasts SIB type 1. SIB type 1 includes search space configuration information and MBS SIB scheduling information. UE100 receives SIB type 1 from gNB200.

[0083] In step S102, gNB200 broadcasts an MBS SIB based on the scheduling indicated by the MBS SIB scheduling information included in SIB type 1. UE100 receives the MBS SIB based on the scheduling indicated by the MBS SIB scheduling information included in SIB type 1. The MBS SIB includes MBS control channel scheduling information.

[0084] In the first operational example, the MBS SIB further includes a search space identifier (hereinafter referred to as the "MBS control channel search space identifier") for the UE100 to receive the MBS control channel. The MBS control channel search space identifier is one of the search space identifiers included in the search space configuration information in SIB type 1. Here, the gNB200 associates one of the multiple search spaces (e.g., search spaces "1" to "4") configured by the search space configuration information in SIB type 1 with the MBS control channel. The gNB200 includes the search space identifier of the search space associated with the MBS control channel in the MBS SIB.

[0085] If multiple MBS control channels are provided in a cell managed by gNB200, gNB200 may associate a different search space with each MBS control channel. In this case, in step S102, gNB200 broadcasts an MBS SIB containing an MBS control channel search space identifier corresponding to each of the multiple MBS control channels. In this case, the MBS SIB includes, for example, a set for each of the multiple MBS control channels: the identifier of the MBS control channel and the MBS control channel search space identifier corresponding to the MBS control channel. The identifier of the MBS control channel may be the MBS session identifier described above. The identifier of the MBS control channel may be a channel identifier assigned to the MBS control channel. The identifier of the MBS control channel may be an RNTI (Radio Network Temporary Identifier) ​​assigned to the MBS control channel.

[0086] In the first operational example, gNB200 may include MBS control channel scheduling information in the MBS SIB only if a specific search space is not associated with an MBS control channel. Here, if an MBS control channel is associated with a specific search space, UE100 can identify the resource range based on pre-configured rules without relying on MBS control channel scheduling information. Therefore, in this case, MBS control channel scheduling information is unnecessary. For this reason, gNB200 includes MBS control channel scheduling information in the MBS SIB only if an MBS control channel is not associated with a specific search space.

[0087] In step S103, UE100 identifies the resource range of the PDCCH to be decoded in order to receive the MBS control channel, based on the MBS control channel scheduling information and MBS control channel search space identifier contained in the MBS SIB received in step S102. Specifically, UE100 first determines the range of MBS control channel reception timing from the MBS control channel scheduling information contained in the MBS SIB received in step S102. Second, UE100 obtains the MBS control channel search space identifier and corresponding search space parameters contained in the MBS SIB received in step S102 from SIB type 1 received in step S101, and identifies the resource range of the PDCCH from the obtained search space parameters.

[0088] When UE100 receives an MBS SIB containing MBS control channel search space identifiers corresponding to each of several MBS control channels, it uses such an MBS SIB to identify the resource range that should be decoded in order to receive the MBS control channel of interest. Specifically, UE100 obtains the MBS control channel search space identifier associated with the MBS control channel of interest, and then identifies the resource range of the PDCCH to be decoded according to the obtained MBS control channel search space identifier.

[0089] In step S104, the gNB200 transmits MBS traffic channel scheduling information on the MBS control channel. The UE100 receives the MBS control channel. Firstly, the UE100 performs decoding (blind decoding) targeting the resource range identified in step S103 and obtains the DCI carried on the PDCCH. Secondly, the UE100 receives the PDSCH scheduled by the DCI and receives the MBS control channel (MBS traffic channel scheduling information) mapped to the PDSCH.

[0090] In step S105, gNB200 transmits MBS data on the MBS traffic channel. UE100 receives the MBS traffic channel (MBS data) based on the MBS traffic channel scheduling information received in step S104.

[0091] (Second example of operation of a mobile communication system) Next, a second example of operation of the mobile communication system 1 according to one embodiment will be described, mainly focusing on the differences from the first example of operation described above.

[0092] In the first operational example described above, it was primarily assumed that a dedicated search space would be allocated for the MBS control channel. In contrast, the second operational example describes an example in which the search space for the MBS control channel and the search space for OSI are shared. This eliminates the need to broadcast information about the MBS control channel's search space via the MBS SIB, enabling more efficient operation.

[0093] In this second operational example, the gNB200 broadcasts an SIB type 1 used for scheduling the MBS SIB, broadcasts the MBS SIB, and transmits scheduling information for the MBS traffic channel on the MBS control channel. Here, the SIB type 1 includes a search space identifier for the UE100 to receive the MBS control channel. Specifically, the search space identifier is applied commonly to the MBS SIB, system information blocks other than SIB type 1, and the MBS control channel.

[0094] Figure 10 shows a second example of operation of the mobile communication system 1. Here, explanations that overlap with the first example of operation described above are omitted.

[0095] As shown in Figure 10, in step S201, gNB200 broadcasts SIB type 1. SIB type 1 includes search space configuration information and MBS SIB scheduling information. In the second example of operation, SIB type 1 further includes an MBS control channel search space identifier. UE100 receives SIB type 1 from gNB200.

[0096] In step S202, UE100 receives an MBS SIB based on SIB type 1. The MBS SIB contains MBS control channel scheduling information.

[0097] In the second operational example, the MBS SIB does not include the MBS control channel search space identifier.

[0098] In step S203, the UE100 identifies the resource range to be decoded in order to receive the MBS control channel, based on the MBS control channel scheduling information received in step S202 and the MBS control channel search space identifier received in step S201.

[0099] The operations in steps S204 to S205 are the same as the operations in steps S104 to S105.

[0100] In the second operational example, the MBS control channel search space identifier may be information that applies in common to both the MBS SIB and the OSI. That is, the search space associated with the SI message carrying the OSI may be the same as the search space associated with the MBS control channel. In this case, in step S201, SIB type 1 may include information indicating that the search space associated with the SI message is the same as the search space associated with the MBS control channel. Such information may be communicated from gNB200 to UE100 by other means.

[0101] In the second example of operation, if the search space associated with the SI message carrying the OSI is the same as the search space associated with the MBS control channel, and the search space associated with the SI message carrying the OSI is a specific search space, UE100 may skip receiving the MBS SIB (the operation in step S202). In such a case, UE100 can identify the resource range based on a pre-configured rule, without relying on the MBS control channel scheduling information. Therefore, in this case, the MBS control channel scheduling information is not required, and UE100 skips receiving the MBS SIB containing the MBS control channel scheduling information.

[0102] (Example of the third operation of a mobile communication system) Next, a third example of operation of the mobile communication system 1 according to one embodiment will be described, mainly focusing on the differences from the first and second examples of operation described above.

[0103] The first and second operational examples described above primarily focused on the search space of the MBS control channel. However, it is also conceivable that search space may be allocated to the MBS traffic channel. This third operational example will explain the search space of the MBS traffic channel.

[0104] In this third operational example, the gNB200 transmits scheduling information for the MBS traffic channel and a search space identifier for the UE100 to receive the MBS traffic channel via the MBS control channel. The search space identifier indicates the search space, which is the resource range that the UE100 will decode, in the physical downlink control channel associated with the MBS traffic channel. This allows the UE100 to identify the search space allocated to the MBS traffic channel, even if a search space is allocated to the MBS traffic channel.

[0105] In this operational example 3, the gNB200 may transmit a search space identifier for each of the multiple MBS traffic channels. That is, the gNB200 may specify a search space for each MBS traffic channel. This makes it possible to assign a different search space to each MBS traffic channel, thus making it easier to alleviate congestion in the search space.

[0106] In this operational example 3, if the MBS traffic channel is not associated with a specific search space (e.g., search space "0"), the gNB200 transmits the MBS traffic channel scheduling information and search space identifier via the MBS control channel. If the MBS traffic channel is associated with a specific search space, the gNB200 transmits the search space identifier without transmitting the MBS traffic channel scheduling information. For specific search spaces, the UE100 can determine its scheduling and resource range itself, thus eliminating the need to transmit the MBS traffic channel scheduling information.

[0107] Figure 11 shows a third example of operation of the mobile communication system 1. Here, explanations that overlap with the first and second examples of operation described above are omitted.

[0108] As shown in Figure 11, in step S301, the UE100 receives the MBS control channel. The MBS control channel carries MBS traffic channel scheduling information.

[0109] In the third operational example, the MBS control channel further carries a search space identifier (hereinafter referred to as the "MBS traffic channel search space identifier") for the UE100 to receive the MBS traffic channel. The MBS traffic channel search space identifier includes one of the search space identifiers included in the search space configuration information in SIB type 1. Here, the gNB200 associates one of the multiple search spaces configured by the search space configuration information in SIB type 1 with the MBS traffic channel. The gNB200 includes the search space identifier of the search space associated with the MBS traffic channel in the MBS traffic channel search space identifier.

[0110] In step S302, the UE100 identifies the resource range to be decoded in order to receive the MBS traffic channel, based on the MBS traffic channel scheduling information and the MBS traffic channel search space identifier received in step S301.

[0111] In step S303, UE100 receives the MBS traffic channel. Firstly, UE100 performs decoding (blind decoding) on ​​the resource range identified in step S302 and obtains the DCI carried by the PDCCH. Secondly, UE100 receives the PDSCH scheduled by the DCI and receives the MBS traffic channel mapped to the PDSCH. UE100 then receives the MBS data carried by the MBS traffic channel.

[0112] In the third operational example, the MBS control channel carries MBS traffic channel scheduling information corresponding to each of the multiple MBS traffic channels. The gNB200 may associate a different search space with each MBS traffic channel. In this case, in step S301, the MBS control channel includes, for each of the multiple MBS traffic channels, a set of identifiers for the MBS traffic channel and the MBS traffic channel search space identifier corresponding to the MBS traffic channel. The identifier for the MBS traffic channel is the TMGI, session identifier, or MBS service identifier. In step S305, the UE100 identifies the resource range to be decoded in order to receive the MBS traffic channels (MBS sessions) of interest to it.

[0113] In the third operational example, if the gNB200 associates a specific search space with an MBS traffic channel, it does not need to transmit MBS traffic channel scheduling information corresponding to that MBS traffic channel in the MBS control channel. Here, if the MBS traffic channel is associated with a specific search space, the UE100 can identify the resource range based on pre-configured rules, without relying on the MBS traffic channel scheduling information. Therefore, the gNB200 does not transmit such MBS traffic channel scheduling information. In the third operational example, an example was shown in which the MBS control channel notifies the MBS traffic channel search space identifier, but the MBS traffic channel search space identifier may also be notified by SIB type 1 or MBS SIB. In this case, the MBS traffic channel search space identifier does not need to be notified by the MBS control channel.

[0114] (Fourth example of operation of a mobile communication system) Next, a fourth example of operation of the mobile communication system 1 according to one embodiment will be explained, mainly focusing on the differences from the first to third examples of operation described above.

[0115] In the first to third operation examples described above, the operation of the gNB200 within its own cell was mainly explained. In this fourth operation example, the gNB200 also notifies the UE100 of information about adjacent cells within its own cell. Figure 12 shows an example of the operating environment in this fourth operation example. As shown in Figure 12, gNB200A manages cell C1, gNB200B manages cell C2, and the UE100 is located in the overlapping area of ​​cells C1 and C2. However, cells C1 and C2 may be managed by a single gNB200.

[0116] In this fourth operational example, the gNB200 (gNB200A) managing cell C1 sends a notification message to the UE100 in cell C1 regarding MBS transmission in the adjacent cell C2, which is different from cell C1. The notification message includes a search space identifier for the UE100 to receive a predetermined channel located in the adjacent cell C2. The predetermined channel is either an MBS control channel or an MBS traffic channel located in the adjacent cell C2. The search space identifier indicates the search space, which is the resource range that the UE100 will decode in the physical downlink control channel associated with the predetermined channel located in the adjacent cell C2. As a result, the UE100, upon receiving the notification message from cell C1, can identify the search space of the MBS control channel or MBS traffic channel located in the adjacent cell C2 based on the notification message.

[0117] In this fourth operational example, if UE100 determines, based on the search space identifier included in the notification message from cell C1, that the search space of a predetermined channel provided in the adjacent cell C2 is a specific search space (for example, search space "0"), it may omit receiving the scheduling information for the predetermined channel transmitted from the adjacent cell C2 and instead receive the predetermined channel provided in the adjacent cell C2. This allows for efficient reception of the MBS control channel or MBS traffic channel of the adjacent cell C2.

[0118] Figure 13 shows a fourth example of operation of the mobile communication system 1. Here, explanations that overlap with the first to third examples of operation described above are omitted. Here, it is assumed that gNB200A manages cell C1 and gNB200B manages cell C2, but one gNB200 may manage both cells C1 and C2. UE100 may be in an RRC idle state or an RRC inactive state.

[0119] As shown in Figure 13, in step S401, gNB200A sends a notification message in cell C1 regarding MBS transmission in cell C2. UE100 receives the notification message in cell C1. The notification message may be an MBS SIB. Alternatively, the notification message may be a message transmitted on the MBS control channel.

[0120] The notification message includes a search space identifier for UE100 to receive a predetermined channel (MBS control channel or MBS traffic channel) located in cell C2. This search space identifier is one of the search space identifiers included in the search space configuration information in SIB type 1 broadcast in cell C2. As a result, when UE100 located in cell C1 changes its serving cell from cell C1 to cell C2, it only needs to acquire SIB type 1 for cell C2 to determine the search space associated with the predetermined channel (MBS control channel or MBS traffic channel) in cell C2.

[0121] In step S401, gNB200A may notify the search space identifier of cell C2 in step S401 only if a specific search space (search space "0") is assigned to a predetermined channel in the adjacent cell C2. Since UE100 can independently determine the scheduling and resource range for a specific search space, if it is determined to be search space "0", it can omit receiving SIB type 1 from the adjacent cell C2. If search space "1" is assigned to a predetermined channel in the adjacent cell C2, gNB200A may not notify the search space identifier of cell C2 in step S401, implicitly indicating that it is not search space "0".

[0122] Alternatively, in step S401, gNB200A may notify the search space identifier of cell C2 only if a specific search space (search space "0") is not assigned to a predetermined channel in the adjacent cell C2.

[0123] In step S402, UE100 decides to receive MBS from cell C2. For example, UE100 may decide to receive MBS from cell C2 if it reaches the cell edge of cell C1 (changing receiving cells on the same frequency), or if the MBS service on the current cell C1 stops due to a change in network settings (changing receiving cells on a different frequency).

[0124] In step S403, UE100 may receive SIB type 1 from cell C2.

[0125] In step S404, UE100 identifies the scheduling and resource range to be decoded in order to receive a predetermined channel of adjacent cell C2, based on the search space identifier of adjacent cell C2 contained in the notification message received in step S401. Here, if UE100 receives SIB type 1 of adjacent cell C2 in step S403, it may further identify the scheduling and resource range to be decoded in order to receive a predetermined channel of adjacent cell C2, based on the search space parameters contained in SIB type 1.

[0126] In step S405, UE100 receives a predetermined channel of cell C2. Here, if the search space identifier notified in step S401 is search space "0", UE100 skips receiving the MBS SIB of the adjacent cell C2 and receives the MBS control channel. Furthermore, if possible, UE100 may skip receiving the MBS control channel and directly receive the MBS traffic channel. On the other hand, if the search space identifier notified in step S401 is not search space "0", UE100 receives the MBS SIB of the adjacent cell C2.

[0127] In the fourth example of operation described above, it was assumed that there was one predetermined channel in the adjacent cell C2, but there may be multiple predetermined channels in the adjacent cell C2. If there are multiple predetermined channels in the adjacent cell C2, the notification message transmitted in step S401 may include a search space identifier for each of the multiple predetermined channels. This allows the UE100 to identify the search space for receiving the desired predetermined channel, even if there are multiple predetermined channels in the adjacent cell C2.

[0128] Furthermore, in the fourth example of operation described above, the notification message may include bandwidth portion information indicating the bandwidth portion to which each of the multiple predetermined channels in the adjacent cell C2 is transmitted. The bandwidth portion is a part of the total bandwidth of the adjacent cell C2. The bandwidth portion may be a BWP as defined in the 5G / NR specification. Alternatively, the bandwidth portion may be a CFR (Common Frequency Resource). This allows the UE100 to properly receive the predetermined channel even when the predetermined channel is transmitted in a limited bandwidth portion. Below, an example in which the bandwidth portion is a BWP (BandWidth Part) will be described.

[0129] For example, gNB200A includes in the notification message (MBS SIB and / or MBS control channel) transmitted in step S401 the transmission BWP information and / or search space identifier for each MBS control channel of the adjacent cell C2. In this case, the notification message includes, for each of the multiple MBS control channels, a set of the identifier of the MBS control channel and the search space identifier corresponding to the MBS control channel. The identifier of the MBS control channel is, for example, the MBS control channel identifier, the channel identifier assigned to the MBS control channel, or the RNTI assigned to the MBS control channel.

[0130] The gNB200A may include in the notification message sent in step S401 the transmission BWP information and / or search space identifier for each MBS traffic channel in the adjacent cell C2. In this case, the notification message includes, for each of the multiple MBS traffic channels, a set of the identifier of the MBS traffic channel and the search space identifier corresponding to the MBS traffic channel. The identifier of the MBS traffic channel is, for example, an MBS traffic channel identifier, a channel identifier assigned to the MBS traffic channel, or an RNTI assigned to the MBS traffic channel.

[0131] UE100 receives an alert message from gNB200A, obtains from the alert message the transmission BWP information and / or search space identifier for the MBS service of interest in the adjacent cell C2 and the corresponding MBS control channel and MBS traffic channel, and identifies the frequency-direction transmission resource and / or temporal-direction transmission opportunity to attempt to receive. Then, UE100 attempts to receive the MBS control channel and / or MBS traffic channel of interest at the identified resource and opportunity.

[0132] (Fifth example of operation of a mobile communication system) Next, a fifth example of operation of the mobile communication system 1 according to one embodiment will be explained, mainly focusing on the differences from the first to fourth examples of operation described above.

[0133] The first to fourth operational examples described above primarily explained the operation related to the identification of the search space. In this fifth operational example, the operation related to the notification of changes to the MBS control channel (hereinafter referred to as "MBS control channel change notification") will be explained. The MBS control channel change notification is a notification indicating that the contents of the MBS control channel, that is, the scheduling information of the MBS traffic channel, have been changed.

[0134] A change notification RNTI is applied to the MBS control channel change notification. The change notification RNTI is used by UE100 to receive an MBS control channel change notification indicating that the content of the corresponding MBS control channel has been changed. It is assumed that the MBS control channel change notification will be used at the start of an MBS session. In this case, the MBS control channel change notification will notify UE100 of the start of the MBS session. However, the MBS control channel change notification may also be used in the middle of a session.

[0135] If multiple MBS control channels are provided in a single cell, multiple MBS control channel change notifications will also be provided. However, UE100 cannot determine which MBS control channel change notification corresponds to which MBS control channel, and there is a risk of receiving unnecessary MBS control channel change notifications.

[0136] In this fifth operational example, the gNB200 managing the cell broadcasts an MBS SIB. The gNB200 transmits multiple MBS control channels in that cell. The MBS SIB includes a change notification RNTI for each of the multiple MBS control channels. This allows the UE100 to know each of the multiple MBS control channels and their corresponding change notification RNTIs, even when multiple MBS control channels are transmitted in the cell.

[0137] In this fifth operational example, UE100 selects one of several change notification RNTIs included in the MBS SIB from among multiple MBS control channels based on the MBS service that UE100 receives. This allows UE100 to identify the change notification RNTI corresponding to the MBS control channel corresponding to the MBS service that UE100 receives, even when multiple MBS control channels are transmitted in the cell.

[0138] Figure 14 shows the fifth example of operation of the mobile communication system 1. Here, explanations that overlap with the first to fourth examples of operation described above are omitted.

[0139] As shown in Figure 14, in step S501, gNB200 broadcasts SIB type 1. SIB type 1 includes search space configuration information and MBS SIB scheduling information. UE100 receives SIB type 1 from gNB200.

[0140] In step S502, gNB200 broadcasts an MBS SIB based on the scheduling indicated by the MBS SIB scheduling information included in SIB type 1. UE100 receives the MBS SIB based on the scheduling indicated by the MBS SIB scheduling information included in SIB type 1. The MBS SIB includes MBS control channel scheduling information. In this example 5, gNB200 broadcasts correspondence information between the MBS control channel and the change notification RNTI in the MBS SIB. For example, gNB200 broadcasts a set of the change notification RNTI and the MBS session identifier (TMGI, session ID, or RNTI of the MBS control channel) in the MBS SIB. If the MBS control channel is assigned an ID, gNB200 may also broadcast a set of the change notification RNTI and the MBS control channel ID in the MBS SIB. UE100 receives the MBS SIB and identifies the change notification RNTI corresponding to the MBS control channel (MBS service). Note that the MBS session does not need to have started at this point.

[0141] In step S503, UE100 performs monitoring using the change notification RNTI (PDCCH monitoring). Here, UE100 may monitor only the change notification RNTI associated with the MBS service of interest. Note that monitoring using the MBS control channel RNTI (PDCCH monitoring) is not required at this point.

[0142] If UE100 receives a change notification RNTI from gNB200 (step S504), in step S505, it starts receiving the MBS control channel (monitoring the MBS control channel RNTI).

[0143] In step S506, UE100 receives the MBS control channel from gNB200.

[0144] In step S507, UE100 receives an MBS traffic channel from gNB200 based on the received MBS control channel.

[0145] (Other embodiments) Each of the above-described operation flows (each operation example) can be performed not only independently, but also in combination of two or more operation flows (operation examples). For example, some steps of one operation flow may be added to another operation flow. Alternatively, some steps of one operation flow may be replaced with some steps of another operation flow.

[0146] In the above embodiment, an example was described in which the base station is an NR base station (gNB), but the base station may also be an LTE base station (eNB). Furthermore, the base station may be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU (Distributed Unit) of an IAB node.

[0147] A program may be provided that causes a computer to perform each of the processes performed by the UE100 or gNB200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or DVD-ROM.

[0148] Alternatively, the circuits that perform each process carried out by the UE100 or gNB200 may be integrated, and at least a portion of the UE100 or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC (System on a chip)).

[0149] Although the embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to those described above, and various design changes can be made without departing from the gist of the invention.

[0150] This application claims priority to U.S. Provisional Application No. 63 / 169334 (filed April 1, 2021), the entirety of which is incorporated into the specification of this application.

Claims

1. A communication control method used in a mobile communication system that provides multicast broadcast services (MBS) from a network device to a user device, The aforementioned network device broadcasts the MBS system information block, The network device transmits scheduling information for MBS traffic channels via the MBS control channel. The MBS system information block includes information about the search space for the user device to receive the MBS control channel. The information regarding the search space includes information that identifies the ControlResourceSetID. Communication control method.

2. A user device that communicates with a network device that provides multicast broadcast services (MBS), The system includes a receiving unit that receives MBS system information blocks from the network device, The receiving unit receives scheduling information for the MBS traffic channel via the MBS control channel. The MBS system information block includes information about the search space for the user device to receive the MBS control channel. The information regarding the search space includes information that identifies the ControlResourceSetID. User device.

3. A processor that controls a user device that communicates with a network device that provides multicast broadcast services (MBS), The process of receiving an MBS system information block from the network device, The process of receiving MBS traffic channel scheduling information via the MBS control channel is executed, The MBS system information block includes information about the search space for the user device to receive the MBS control channel. The information regarding the search space includes information that identifies the ControlResourceSetID. Processor.

4. A network device that provides multicast broadcast services (MBS) to user devices, It includes a transmission unit that broadcasts MBS system information blocks, The transmission unit transmits scheduling information for the MBS traffic channel via the MBS control channel. The MBS system information block includes information about the search space for the user device to receive the MBS control channel. The information regarding the search space includes information that identifies the ControlResourceSetID. Network device.

5. A mobile communication system that provides multicast broadcast services (MBS) from network devices to user devices, The aforementioned network device broadcasts an MBS system information block. The network device transmits scheduling information for MBS traffic channels via the MBS control channel. The MBS system information block includes information about the search space for the user device to receive the MBS control channel. The information regarding the search space includes information that identifies the ControlResourceSetID. Mobile communication system.

6. A program for controlling user devices that communicate with network devices providing multicast broadcast services (MBS), The process of receiving an MBS system information block from the network device, The user device is instructed to perform the process of receiving scheduling information for the MBS traffic channel via the MBS control channel. The MBS information block includes information about the search space for the user device to receive the MBS control channel. The information regarding the search space includes information that identifies the ControlResourceSetID. program.

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