Communication method, relay device, system, program and chipset

Abstract

To appropriately control a relay device that performs relay transmission between a base station and a user device.SOLUTION: A communication method that is used in a mobile communication system comprises: broadcasting, by a base station, relay device support information that indicates supporting of a control terminal included in a relay device or information associated with a reserved cell; determining, by the control terminal, that access to the base station is permitted in response to reception of the relay device support information; and neglecting, by the control terminal, the information associated with the reserved cell that is broadcast from the base station.SELECTED DRAWING: Figure 19

Description

Technical Field

[0001] The present disclosure relates to a communication method, a relay device, a system, a program, and a chipset 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 of the 5G system, enables broadband transmission in a high-frequency band compared to LTE (Long Term Evolution), which is a fourth-generation radio access technology.

[0003] Since radio signals (radio waves) in high-frequency bands such as the millimeter-wave band or the terahertz band have high directivity, reducing the coverage of base stations becomes an issue. To solve such an issue, a repeater device, which is a type of relay device that relays radio signals between a base station and a user device and can be controlled from a network, has attracted attention (see, for example, Non-Patent Document 1). Such a repeater device can expand the coverage of a base station while suppressing the occurrence of interference, for example, by amplifying radio signals received from the base station and transmitting them by directional transmission.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

[0005] The communication method according to the first aspect is a communication method used in a mobile communication system, and includes a step in which a base station forms a plurality of beams in one cell by beam sweeping, and a step in which, when the base station subjects only some of the plurality of beams to access control, the base station broadcasts first information indicating that access control is performed on a beam-by-beam basis in the some of the beams.

[0006] The communication method according to the second aspect is a communication method used in a mobile communication system, and includes a step in which a first network node that manages a first cell controls a relay device that relays a radio signal between the first network node and a user device in the first cell, and a step in which the first network node communicates control state information regarding a control state of the relay device with a second network node that manages a second cell adjacent to the first cell.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0008] When controlling a relay device such as a repeater device from a network, the control technology for specifically how to control the relay device has not yet been established, and it is currently difficult to perform efficient coverage expansion using the relay device.

[0009] Therefore, an object of the present disclosure is to enable appropriate control of a relay device that performs relay transmission between a base station and a user device.

[0010] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0011] (1) First Embodiment First, the first embodiment will be described. The relay device according to the first embodiment is a repeater device that can be controlled from a network.

[0012] (1.1) Outline of Mobile Communication System FIG. 1 is a diagram showing the configuration of a mobile communication system according to the first embodiment. The mobile communication system 1 complies with the 5th Generation System (5GS) of the 3rd Generation Partnership Project (3GPP) (registered trademark; the same shall apply hereinafter). 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. The 6th Generation (6G) system may be at least partially applied to the mobile communication system.

[0013] The mobile communication system 1 includes a User Equipment (UE) 100, a 5G Radio Access Network (NG-RAN) 10, and a 5G Core Network (5GC) 20. Hereinafter, the NG-RAN 10 may be simply referred to as the RAN 10. Also, the 5GC 20 may be simply referred to as the Core Network (CN) 20.

[0014] 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 is a mobile phone terminal (including a smartphone) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided on the sensor, a vehicle or a device provided on the vehicle (Vehicle UE), an aircraft or a device provided on the aircraft (Aerial UE).

[0015] 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 own cell. The gNB 200 has functions such as a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), and a measurement control function for mobility control and scheduling. A "cell" is used as a term indicating the smallest unit of a wireless communication area. A "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 (hereinafter simply referred to as "frequency").

[0016] The gNB 200 may be functionally split into a central unit (CU) and a distributed unit (DU). The CU controls the DU. The CU is a unit that includes upper layers included in the protocol stack described below, for example, the RRC layer, the SDAP layer, and the PDCP layer. The CU is connected to the core network via the NG interface, which is a backhaul interface. The CU is connected to an adjacent base station via the Xn interface, which is an interface between base stations. The DU forms a cell. The DU 202 is a unit that includes lower layers included in the protocol stack described below, for example, the RLC layer, the MAC layer, and the PHY layer. The DU is connected to the CU via the F1 interface, which is a fronthaul interface.

[0017] 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.

[0018] 5GC20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE100. The AMF manages the mobility of the UE100 by communicating with the UE100 using NAS (Non-Access Stratum) signaling. The UPF performs data transfer control. The AMF and the UPF are connected to the gNB200 via the NG interface, which is an interface between the base station and the core network.

[0019] Figure 2 is a diagram showing the configuration of the protocol stack of the radio interface of the user plane that handles data.

[0020] The radio interface protocol of the user plane 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.

[0021] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Between the PHY layer of the UE100 and the PHY layer of the gNB200, data and control information are transmitted via a physical channel. The PHY layer of the UE100 receives downlink control information (DCI) transmitted on the physical downlink control channel (PDCCH) from the gNB200. Specifically, the UE100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and obtains the DCI that was successfully decoded as DCI addressed to itself. The DCI transmitted from the gNB200 has CRC parity bits scrambled by the RNTI added to it.

[0022] In addition, gNB200 transmits a Synchronization Signal / PBCH block (SSB). For example, an SSB is composed of four consecutive Orthogonal Frequency Division Multiplex (OFDM) symbols, and a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a Physical Broadcast Channel (PBCH) / Master Information Block (MIB), and a Demodulation Reference Signal (DMRS) of the PBCH are arranged. The bandwidth of the SSB is, for example, 240 consecutive subcarriers, that is, a bandwidth of 20 resource blocks (RBs).

[0023] The MAC layer performs priority control of data, retransmission processing by Hybrid Automatic Repeat reQuest (HARQ), and random access procedures, etc. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of gNB200 via a transport channel. The MAC layer of gNB200 includes a scheduler. The scheduler determines the transport format (transport block size, Modulation and Coding Scheme (MCS)) of the uplink and downlink and the resource blocks allocated to UE100.

[0024] The RLC layer uses the functions of the MAC layer and the PHY layer to transmit data to the RLC layer on the receiving side. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of gNB200 via a logical channel.

[0025] The PDCP layer performs header compression / expansion, encryption / decryption, etc.

[0026] The SDAP layer performs mapping between an IP flow, which is a unit for the core network to perform Quality of Service (QoS) control, and a radio bearer, which is a unit for the Access Stratum (AS) to perform QoS control. Note that when the Radio Access Network (RAN) is connected to the Evolved Packet Core (EPC), the SDAP may not be necessary.

[0027] Figure 3 is a diagram showing the configuration of the protocol stack of the radio interface of the control plane that handles signaling (control signals).

[0028] The protocol stack of the radio interface of the control plane has an RRC (Radio Resource Control) layer and an NAS (Non-Access Stratum) layer instead of the SDAP layer shown in Figure 2.

[0029] Between the RRC layer of UE100 and the RRC layer of gNB200, RRC signaling for various settings is transmitted. The RRC layer controls logical channels, transport channels, and physical channels in response to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in the RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in the RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in the RRC inactive state.

[0030] The NAS layer located above the RRC layer performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of UE100 and the NAS layer of AMF300A. Note that UE100 has an application layer etc. in addition to the protocol of the radio interface. Also, the layer below the NAS layer is called the AS layer.

[0031] (1.2) An example of the application scenario of the relay device Figures 4 and 5 are diagrams showing an example of the application scenario of the NCR device according to the first embodiment.

[0032] 5G / NR enables broadband transmission in higher frequency bands compared to 4G / LTE. Since wireless signals in higher frequency bands such as the millimeter wave band or the terahertz wave band have high directivity, reducing the coverage of gNB200 becomes an issue. In Figure 4, UE100 may be located outside the coverage area of gNB200, for example, outside the area where it can directly receive wireless signals from gNB200. There may be an obstacle between gNB200 and UE100, and UE100 may not be able to communicate with gNB200 in line of sight.

[0033] As shown in Figure 4, a repeater device (500A), which is a type of relay device that relays wireless signals between gNB200 and UE100 and can be controlled from a network, is introduced into the mobile communication system 1. Hereinafter, such a repeater device is referred to as an NCR (Network-Controlled Repeater) device. Such a repeater device may also be referred to as a smart repeater device.

[0034] For example, the NCR device 500A amplifies the wireless signal (radio wave) received from gNB200 and transmits it by directional transmission. Specifically, the NCR device 500A receives the wireless signal transmitted by gNB200 through beamforming. Then, the NCR device 500A amplifies the received wireless signal without demodulating and modulating it, and transmits the amplified wireless signal by directional transmission. Here, the NCR device 500A may transmit the wireless signal with a fixed directivity (beam). The NCR device 500A may also transmit the wireless signal with a variable (adaptive) directional beam. Thereby, the coverage of gNB200 can be efficiently extended. In the first embodiment, it is mainly assumed that the NCR device 500A is applied to the downlink communication from gNB200 to UE100, but the NCR device 500A can also be applied to the uplink communication from UE100 to gNB200.

[0035] Also, as shown in FIG. 5, a new UE (hereinafter referred to as "NCR-MT (Mobile termination)") 520A, which is a type of control terminal for controlling the NCR device 500A, is introduced. That is, the NCR device 500A is a type of repeater that relays the radio signals transmitted between the gNB 200 and the UE 100. Specifically, it is an NCR-Fwd (Forward) 510A that changes the propagation state of the radio signal without demodulating and modulating the radio signal, and an NCR-MT 520A that performs wireless communication with the gNB 200 to control the NCR-Fwd 510A. In this way, the NCR-MT 520A controls the NCR device 500A in cooperation with the gNB 200 by establishing a wireless connection with the gNB 200 and performing wireless communication with the gNB 200. Thereby, efficient coverage expansion can be realized using the NCR device 500A. The NCR-MT 520A controls the NCR device 500A according to the control from the gNB 200.

[0036] The NCR-MT 520A may be configured separately from the NCR-Fwd 510A. For example, the NCR-MT 520A may be in the vicinity of the NCR-Fwd 510A and electrically connected to the NCR-Fwd 510A. The NCR-MT 520A may be connected to the NCR-Fwd 510A by wire or wirelessly. Alternatively, the NCR-MT 520A may be configured integrally with the NCR-Fwd 510A. The NCR-MT 520A and the NCR-Fwd 510A may be fixedly installed, for example, at the coverage edge (cell edge) of the gNB 200, or on the wall surface or window of some building. The NCR-MT 520A and the NCR-Fwd 510A may be installed on a vehicle or the like and be movable. Also, one NCR-MT 520A may control a plurality of NCR-Fwd 510A.

[0037] In the example shown in FIG. 5, the NCR device 500A (NCR-Fwd510A) dynamically or quasi-statically changes the beam to be transmitted or received. For example, NCR-Fwd510A forms a beam toward each of UE100a and UE100b. Also, NCR-Fwd510A may form a beam toward gNB200. For example, in the communication resources between gNB200 and UE100a, NCR-Fwd510A transmits the radio signal received from gNB200 to UE100a by beamforming, and / or transmits the radio signal received from UE100a to gNB200 by beamforming. In the communication resources between gNB200 and UE100b, NCR-Fwd510A transmits the radio signal received from gNB200 to UE100b by beamforming, and / or transmits the radio signal received from UE100b to gNB200 by beamforming. Instead of or in addition to forming a beam, NCR-Fwd510A may perform null forming (so-called null steering) toward a UE100 (not shown) that is not a communication partner and / or an adjacent gNB200 (not shown) for interference suppression.

[0038] FIG. 6 is a diagram showing an example of a control method of the NCR device 500A according to the first embodiment. As shown in FIG. 6, NCR-Fwd510A relays a radio signal (also referred to as a "UE signal") between gNB200 and UE100. The UE signal includes an uplink signal (also referred to as a "UE-UL signal") transmitted from UE100 to gNB200 and a downlink signal (also referred to as a "UE-DL signal") transmitted from gNB200 to UE100. NCR-Fwd510A relays the UE-UL signal from UE100 to gNB200 and relays the UE-DL signal from gNB200 to UE100. The radio link between NCR-Fwd510A and UE100 is also referred to as an "access link". The radio link between NCR-Fwd510A and gNB200 is also referred to as a "backhaul link".

[0039] The NCR-MT520A transmits and receives a wireless signal (hereinafter referred to as the "NCR-MT signal") to and from the gNB200. The NCR-MT signal includes an uplink signal transmitted from the NCR-MT520A to the gNB200 (referred to as the "NCR-MT-UL signal") and a downlink signal transmitted from the gNB200 to the NCR-MT520A (referred to as the "NCR-MT-DL signal"). The NCR-MT-UL signal includes signaling for controlling the NCR device 500A. The wireless link between the NCR-MT520A and the gNB200 is also referred to as the "control link".

[0040] Based on the NCR-MT-UL signal from the NCR-MT520A, the gNB200 directs a beam at the NCR-MT520A. Since the NCR device 500A is co-located with the NCR-MT520A, if the frequencies of the backhaul link and the control link are the same, when the gNB200 directs a beam at the NCR-MT520A, as a result, the NCR-Fwd510A will also be beamed at. The gNB200 uses the beam to transmit the NCR-MT-DL signal and the UE-DL signal. The NCR-MT520A receives the NCR-MT-DL signal. If the NCR-Fwd510A and the NCR-MT520A are at least partially integrated, in the NCR-Fwd510A and the NCR-MT520A, functions for transmitting and receiving or relaying UE signals and / or NCR-MT signals (for example, antennas) may be integrated. Note that the beam includes a transmission beam and / or a reception beam. The beam is a general term for transmission and / or reception by control to maximize the power of the transmission wave and / or reception wave in a specific direction by adjusting / adapting antenna weights and the like.

[0041] FIG. 7 is a diagram showing a configuration example of a protocol stack in a mobile communication system 1 having an NCR device 500A according to the first embodiment. NCR-Fwd510A relays radio signals transmitted and received between the gNB 200 and the UE 100. NCR-Fwd510A has an RF (Radio Frequency) function of amplifying and relaying the received radio signals, and performs directional transmission by beamforming (for example, analog beamforming).

[0042] NCR-MT520A has at least one layer (entity) among PHY, MAC, RRC, and F1-AP (Application Protocol). F1-AP is a type of fronthaul interface. NCR-MT520A exchanges downlink signaling and / or uplink signaling with the gNB 200 through at least one of PHY, MAC, RRC, and F1-AP. If NCR-MT520A is a type or part of a base station, NCR-MT520A may exchange information with the gNB 200 through the Xn-AP (Xn Application Protocol) which is an interface between base stations.

[0043] (1.3) Configuration example of relay device FIG. 8 is a diagram showing a configuration example of an NCR device 500A which is a relay device according to the first embodiment. The NCR device 500A includes an NCR-Fwd510A, an NCR-MT520A, and an interface 530.

[0044] The NCR-Fwd510A has a wireless unit 511A and an NCR control unit 512A. The wireless unit 511A has an antenna unit 511a including a plurality of antennas (a plurality of antenna elements), an RF circuit 511b including an amplifier, and a directivity control unit 511c for controlling the directivity of the antenna unit 511a. The RF circuit 511b amplifies and relays (transmits) the wireless signal transmitted and received by the antenna unit 511a. The RF circuit 511b may convert the wireless signal, which is an analog signal, into a digital signal, and then reconvert it into an analog signal after digital signal processing. The directivity control unit 511c may perform analog beamforming by analog signal processing. The directivity control unit 511c may perform digital beamforming by digital signal processing. The directivity control unit 511c may perform an analog and digital hybrid type of beamforming. The NCR control unit 512A controls the wireless unit 511A according to a control signal from the NCR-MT520A. The NCR control unit 512A may include at least one processor. The NCR control unit 512A may output information regarding the capabilities of the NCR device 500A to the NCR-MT520A.

[0045] The NCR-MT520A has a receiving unit 521, a transmitting unit 522, and a control unit 523. The receiving unit 521 performs various receptions under the control of the control unit 523. The receiving unit 521 includes an antenna and a receiver. The receiver converts a radio signal (radio signal) received by the antenna into a baseband signal (received signal) and outputs it to the control unit 523. The transmitting unit 522 performs various transmissions under the control of the control unit 523. The transmitting unit 522 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 523 into a radio signal and transmits it from the antenna. The control unit 523 performs various controls in the NCR-MT520A. The control unit 523 includes at least one processor and at least one memory. The memory stores a program executed by the processor and information used for the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of the baseband signal, etc. The CPU executes a program stored in the memory to perform various processes. Also, the control unit 523 executes the functions of at least one layer of PHY, MAC, RRC, and F1-AP.

[0046] The interface 530 electrically connects the NCR-Fwd510A and the NCR-MT520A. The control unit 523 of the NCR-MT520A controls the NCR-Fwd510A via the interface 530.

[0047] In the first embodiment, the receiving unit 521 of the NCR-MT520A receives signaling (downlink signaling) used for the control of the NCR device 500A from the gNB200 by wireless communication. The control unit 523 of the NCR-MT520A controls the NCR device 500A based on the signaling. Thereby, the gNB200 can control the NCR-Fwd510A via the NCR-MT520A.

[0048] In the first embodiment, the control unit 523 of the NCR-MT520A may transmit NCR capability information indicating the capabilities of the NCR device 500A to the gNB200 via wireless communication. The NCR capability information is an example of uplink signaling from the NCR-MT520A to the gNB200. This enables the gNB200 to grasp the capabilities of the NCR device 500A.

[0049] (1.4) Configuration example of the base station FIG. 9 is a diagram showing a configuration example of the gNB200 according to the first embodiment. The gNB200 includes a transmission unit 210, a reception unit 220, a control unit 230, and a backhaul communication unit 240.

[0050] The transmission unit 210 performs various transmissions under the control of the control unit 230. The transmission 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. The reception unit 220 performs various receptions under the control of the control unit 230. The reception unit 220 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (reception signal) and outputs it to the control unit 230. The transmission unit 210 and the reception unit 220 may be capable of beamforming using a plurality of antennas.

[0051] 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 the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of the baseband signal, etc. The CPU executes the programs stored in the memory to perform various processes.

[0052] The backhaul communication unit 240 is connected to an adjacent base station via a base station interface. The backhaul communication unit 240 is connected to the AMF / UPF 300 via a base station-core network interface. Note that the gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally split), and the two units may be connected by an F1 interface.

[0053] In the first embodiment, the transmission unit 210 of the gNB 200 transmits, by wireless communication, signaling (downlink signaling) used for controlling the NCR-Fwd 510A to the NCR-MT 520A. Thereby, the gNB 200 can control the NCR device 500A via the NCR-MT 520A. In the first embodiment, the reception unit 220 of the gNB 200 may receive, by wireless communication, NCR capability information indicating the capabilities of the NCR device 500A from the NCR-MT 520A.

[0054] (1.5) An example of downlink signaling FIG. 10 is a diagram showing an example of downlink signaling from the gNB 200 to the NCR-MT 520A according to the first embodiment.

[0055] gNB 200 (Transmission Unit 210) transmits downlink signaling to NCR-MT520A. The downlink signaling may be an RRC message, which is signaling of the RRC layer (i.e., layer 3). The downlink signaling may be a MAC CE (Control Element), which is signaling of the MAC layer (i.e., layer 2). The downlink signaling may be downlink control information (DCI), which is signaling of the PHY layer (i.e., layer 1). The downlink signaling may be UE-specific signaling. The downlink signaling may be broadcast signaling. The downlink signaling may be a fronthaul message (e.g., an F1-AP message). If NCR-MT520A is a type or part of a base station, NCR-MT520A may communicate with gNB 200 via the Xn AP (Xn-AP) of the base station interface Xn.

[0056] For example, the gNB 200 (transmission unit 210) transmits, as downlink signaling, an NCR control signal for designating the operating state of the NCR device 500A to the NCR-MT520A that has established a radio connection with the gNB 200 (step S1A). The NCR control signal for designating the operating state of the NCR device 500A may be a MAC CE that is signaling at the MAC layer (layer 2) or DCI that is signaling at the PHY layer (layer 1). However, the NCR control signal may be included in an RRC Reconfiguration message, which is a type of UE-specific RRC message, and transmitted to the NCR-MT520A. The downlink signaling may be a message of a layer higher than the RRC layer (for example, the NCR application). The downlink signaling may encapsulate a message of a layer higher than the RRC layer and transmit it as a message of a layer below the RRC layer. Note that the NCR-MT520A (transmission unit 522) may transmit an uplink response message to the downlink signaling from the gNB 200. The response message may be transmitted in response to the NCR device 500A completing or receiving the setting specified by the downlink signaling.

[0057] The NCR control signal may include frequency control information for designating the center frequency of a radio signal (for example, a component carrier) that the NCR-Fwd510A is to relay. When the NCR control signal received from the gNB 200 includes frequency control information, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A to relay the radio signal having the center frequency indicated by the frequency control information (step S2A). The NCR control signal may include a plurality of pieces of frequency control information designating different center frequencies. By including the frequency control information in the NCR control signal, the gNB 200 can specify, via the NCR-MT520A, the center frequency of the radio signal that the NCR-Fwd510A is to relay.

[0058] The NCR control signal may include mode control information that specifies the operating mode of the NCR-Fwd510A. The mode control information may be associated with frequency control information (center frequency). The operating mode may be any one of a mode in which the NCR-Fwd510A performs omnidirectional transmission and / or reception, a mode in which the NCR-Fwd510A performs fixed-directional transmission and / or reception, a mode in which the NCR-Fwd510A performs transmission and / or reception using a variable-directional beam, and a mode in which the NCR-Fwd510A performs MIMO (Multiple Input Multiple Output) relay transmission. The operating mode may be any one of a beamforming mode (i.e., a mode that emphasizes desired wave improvement) and a null steering mode (i.e., a mode that emphasizes interference wave suppression). When the NCR control signal received from the gNB200 includes mode control information, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A to operate in the operating mode indicated by the mode control information (step S2A). By including mode control information in the NCR control signal, the gNB200 can specify the operating mode of the NCR-Fwd510A via the NCR-MT520A.

[0059] Here, the mode in which the NCR device 500A performs omnidirectional transmission and / or reception is a mode in which the NCR-Fwd510A performs relay in all directions, and may be referred to as the omnidirectional mode. The mode in which the NCR-Fwd510A performs transmission and / or reception with a fixed directivity may be a directive mode realized by one directive antenna. The mode may be a beamforming mode realized by applying fixed phase and amplitude control (antenna weight control) to a plurality of antennas. Any of these modes may be specified (set) by the gNB200 for the NCR-MT520A. The mode in which the NCR-Fwd510A performs transmission and / or reception with a variable directive beam may be a mode of performing analog beamforming. The mode may be a mode of performing digital beamforming. The mode may be a mode of performing hybrid beamforming. The mode may be a mode of forming an adaptive beam specific to the UE100. Any of these modes may be specified (set) by the gNB200 for the NCR-MT520A. Note that in the operation mode of performing beamforming, beam control information described later may be provided from the gNB200 to the NCR-MT520A. The mode in which the NCR device 500A performs MIMO relay transmission may be a mode of performing SU (Single-User) spatial multiplexing. The mode may be a mode of performing MU (Multi-User) spatial multiplexing. The mode may be a mode of performing transmit diversity. Any of these modes may be specified (set) by the gNB200 for the NCR-MT520A by an NCR control signal. The operation mode may include a mode of turning on (activating) the relay transmission by the NCR-Fwd510A and a mode of turning off (deactivating) the relay transmission by the NCR-Fwd510A. Any of these modes may be specified (set) by the gNB200 for the NCR-MT520A by an NCR control signal.

[0060] The NCR control signal may include beam control information that specifies the transmission direction, transmission weight, or beam pattern when the NCR-Fwd510A performs directional transmission. The beam control information may be associated with frequency control information (center frequency). The beam control information may include a PMI (Precoding Matrix Indicator). The beam control information may include angle information for beamforming. When the NCR control signal received by the NCR-MT520A (control unit 523) from the gNB200 includes beam control information, the NCR-Fwd510A is controlled to form the transmission directivity (beam) indicated by the beam control information (step S2A). Since the NCR control signal includes beam control information, the gNB200 can control the transmission directivity of the NCR device 500A via the NCR-MT520A.

[0061] The NCR control signal may include output control information that specifies the degree of amplification (amplification gain) or transmission power when the NCR-Fwd510A amplifies a radio signal. The output control information may be information indicating the difference value (i.e., relative value) between the current amplification gain or transmission power and the target amplification gain or transmission power. When the NCR control signal received by the NCR-MT520A (control unit 523) from the gNB200 includes output control information, the NCR-Fwd510A is controlled to change to the amplification gain or transmission power indicated by the output control information (step S2A). The output control information may be associated with frequency control information (center frequency). The output control information may be information specifying any one of the amplifier gain, beamforming gain, and antenna gain of the NCR-Fwd510A. The output control information may be information specifying the transmission power of the NCR-Fwd510A.

[0062] When one NCR-MT520A controls a plurality of NCR-Fwd510A, the gNB200 (transmission unit 210) may transmit an NCR control signal to the NCR-MT520A for each NCR-Fwd510A. In this case, the NCR control signal may include an identifier (NCR identifier) of the corresponding NCR-Fwd510A. The NCR-MT520A (control unit 523) that controls a plurality of NCR-Fwd510A determines the NCR-Fwd510A to which the NCR control signal is to be applied based on the NCR identifier included in the NCR control signal received from the gNB200. Note that the NCR identifier may be transmitted from the NCR-MT520A to the gNB200 together with the NCR control signal even when the NCR-MT520A controls only one NCR-Fwd510A.

[0063] In this way, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A based on the NCR control signal from the gNB200. Thereby, the gNB200 can control the NCR-Fwd510A via the NCR-MT520A.

[0064] (1.6) An example of uplink signaling FIG. 11 is a diagram showing an example of uplink signaling from the NCR-MT520A to the gNB200 according to the first embodiment.

[0065] The NCR-MT520A (transmission unit 210) transmits uplink signaling to the gNB 200. The uplink signaling may be an RRC message which is signaling of the RRC layer. The uplink signaling may be a MAC CE which is signaling of the MAC layer. The uplink signaling may be uplink control information (UCI) which is signaling of the PHY layer. The uplink signaling may be a fronthaul message (e.g., an F1-AP message). The uplink signaling may be an inter-base station message (e.g., an Xn-AP message). The uplink signaling may be a message of a layer higher than the RRC layer (e.g., an NCR application). The uplink signaling may encapsulate a message of a layer higher than the RRC layer with a message of a layer lower than the RRC layer and transmit it. That is, the uplink signaling stores a higher layer message in a lower layer container. Note that the gNB 200 (transmission unit 210) may transmit a response message to the uplink signaling from the NCR-MT520A in the downlink, and the NCR-MT520A (reception unit 521) may receive the response message.

[0066] For example, the NCR-MT520A (transmission unit 522) that has established a radio connection with the gNB 200 transmits NCR capability information indicating the capabilities of the NCR device 500A to the gNB 200 as uplink signaling (step S5A). The NCR-MT520A (transmission unit 522) may include the NCR capability information in a UE Capability message or a UE Assistant Information message which is a type of RRC message and transmit it to the gNB 200. The NCR-MT520A (transmission unit 522) may transmit the NCR capability information (NCR capability information and / or operating state information) to the gNB 200 in response to a request or inquiry from the gNB 200.

[0067] The NCR capability information may include corresponding frequency information indicating the frequencies supported by NCR-Fwd510A. The corresponding frequency information may be a numerical value or index indicating the center frequency of the frequencies supported by NCR-Fwd510A. The corresponding frequency information may also be a numerical value or index indicating the range of the frequencies supported by NCR-Fwd510A. When the NCR capability information received from NCR-MT520A by gNB200 (control unit 230) includes the corresponding frequency information, gNB200 (control unit 230) can grasp the frequencies supported by NCR-Fwd510A based on the corresponding frequency information. Then, gNB200 (control unit 230) may set the center frequency of the radio signal targeted by NCR device 500A within the range of the frequencies supported by NCR-Fwd510A.

[0068] The NCR capability information may include mode capability information regarding the operation modes supported by the NCR-Fwd510A or the switching between operation modes. As described above, the operation modes may include at least one of the following modes: a mode in which the NCR-Fwd510A performs omnidirectional transmission and / or reception, a mode in which the NCR-Fwd510A performs fixed-directional transmission and / or reception, a mode in which the NCR-Fwd510A performs transmission and / or reception using a variable-directional beam, and a mode in which the NCR-Fwd510A performs MIMO (Multiple Input Multiple Output) relay transmission. The operation mode may be either a beamforming mode (i.e., a mode that emphasizes improving the desired wave) or a null steering mode (i.e., a mode that emphasizes suppressing interference waves). The mode capability information may indicate which of these operation modes the NCR-Fwd510A is capable of supporting. The mode capability information may also indicate which of these operation modes can be switched between. When the NCR capability information received from the NCR-MT520A includes mode capability information, the gNB200 (control unit 230) can determine the operation mode and mode switching supported by the NCR-Fwd510A based on the mode capability information. Then, the gNB200 (control unit 230) may set the operation mode of the NCR-Fwd510A within the determined operation mode and mode switching range.

[0069] The NCR capability information may include beam capability information indicating the beam variable range, beam variable resolution, or the number of variable patterns when the NCR-Fwd510A performs transmission and / or reception using a variable directional beam. The beam capability information may be, for example, information indicating the variable range of the beam angle (e.g., controllable within 30° to 90°) based on the horizontal or vertical direction. The beam capability information may be information indicating the absolute angle. The beam capability information may be represented by the azimuth and / or elevation angle at which the beam is directed. The beam capability information may be information indicating the angle change per variable step (e.g., 5° / step horizontally, 10° / step vertically). The beam capability information may be information indicating the number of variable steps (e.g., 10 steps horizontally, 20 steps vertically). The beam capability information may be information indicating the number of variable patterns of the beam in the NCR-Fwd510A (e.g., a total of 10 patterns from beam pattern 1 to 10). When the NCR capability information received from the NCR-MT520A by the gNB200 (control unit 230) includes the beam capability information, the gNB200 (control unit 230) can grasp the beam angle change or beam pattern that the NCR-Fwd510A can handle based on the beam capability information. Then, the gNB200 (control unit 230) may set the beam of the NCR-Fwd510A within the grasped range of the beam angle change or beam pattern. These beam capability information may be null capability information. In the case of null capability information, these beam capability information indicate the null control capability when null steering is performed.

[0070] The NCR capability information may include control delay information indicating the control delay time in the NCR device 500A. For example, the control delay information is information indicating the delay time (e.g., 1 ms, 10 ms, etc.) from the timing when the UE100 receives the NCR control signal or the timing when the completion of the setting for the NCR control signal is transmitted to the gNB200 until the control (change of the operation mode and / or change of the beam) according to the NCR control signal is completed. When the NCR capability information received from the NCR-MT520A by the gNB200 (control unit 230) includes the control delay information, the gNB200 (control unit 230) can grasp the control delay time in the NCR-Fwd510A based on the control delay information.

[0071] The NCR capability information may include amplification characteristic information regarding the amplification characteristics or output power characteristics of the radio signal in the NCR-Fwd510A. The amplification characteristic information may be information indicating the amplifier gain (dB), beamforming gain (dB), and antenna gain (dBi) of the NCR-Fwd510A. The amplification characteristic information may be information indicating the amplification variable range (e.g., 0 dB to 60 dB) in the NCR-Fwd510A. The amplification characteristic information may be information indicating the number of steps of the amplification degree that can be changed by the NCR-Fwd510A (e.g., 10 steps), or the amplification degree per variable step (e.g., 10 dB / step). The amplification characteristic information may be information indicating the variable range of the output power of the NCR-Fwd510A (e.g., 0 dBm to 30 dBm). The amplification characteristic information may be information indicating the number of steps of the output power that can be changed by the NCR-Fwd510A (e.g., 10 steps), or the output power per variable step (e.g., 10 dBm / step, or 10 dB / step).

[0072] The NCR capability information may include position information indicating the installation position of the NCR device 500A. The position information may include any one or more of latitude, longitude, and altitude. The position information may include information indicating the distance and / or installation angle of the NCR device 500A with respect to the gNB 200. The installation angle may be a relative angle with respect to the gNB 200, or may be a relative angle with respect to, for example, north, vertical, or horizontal. The installation position may be the position information of the place where the antenna unit 511a of the NCR-Fwd510A is installed.

[0073] The NCR capability information may include antenna information indicating the number of antennas of the NCR-Fwd510A. The antenna information may be information indicating the number of antenna ports of the NCR-Fwd510A. The antenna information may be information indicating the degree of freedom of directivity control (beam or null formation). The degree of freedom indicates how many beams can be formed (controlled), and is usually "(number of antennas) - 1". For example, in the case of two antennas, the degree of freedom is 1. In the case of two antennas, a figure-eight beam pattern is formed, but since directivity control is possible in only one direction, the degree of freedom is 1.

[0074] When the NCR-MT520A controls a plurality of NCR-Fwd510A, the NCR-MT520A (transmission unit 522) may transmit the NCR capability information to the gNB200 for each NCR-Fwd510A. In this case, the NCR capability information may include the number of NCR-Fwd510A and / or the identifier of the corresponding NCR-Fwd510A (NCR identifier). Also, when the NCR-MT520A controls a plurality of NCR-Fwd510A, the NCR-MT520A (transmission unit 522) may transmit information indicating at least one of the identifiers of the plurality of NCR-Fwd510A and the number of the plurality of NCR-Fwd510A. Note that the NCR identifier may be transmitted from the NCR-MT520A to the gNB200 together with the NCR capability information even when the NCR-MT520A controls only one NCR-Fwd510A.

[0075] (1.7) An example of the overall operation sequence FIG. 12 is a diagram showing an example of the overall operation sequence of the mobile communication system 1 according to the first embodiment. In the sequence diagrams referred to in the following embodiments, steps that are not essential are indicated by broken lines. Note that, although details will be described later, "NCR" in FIG. 12 may be read as "RIS".

[0076] In step S11, gNB200 (transmission unit 210) broadcasts NCR support information indicating that gNB200 supports NCR-MT520A. For example, gNB200 (transmission unit 210) broadcasts a system information block (SIB) including the NCR support information. The NCR support information may be information indicating that NCR-MT520A is accessible. Alternatively, gNB200 (transmission unit 210) may broadcast NCR non-support information indicating that gNB200 does not support NCR-MT520A. The NCR non-support information may be information indicating that NCR-MT520A is inaccessible.

[0077] At this stage, NCR-MT520A may be in the RRC idle state or the RRC inactive state. NCR-MT520A (control unit 523) that has not established a radio connection with gNB200 may determine that access to the gNB200 is permitted in response to receiving the NCR support information from the gNB200, and may perform an access operation to establish a radio connection with the gNB200. NCR-MT520A (control unit 523) may perform cell reselection considering the gNB200 (cell) that permits access as having the highest priority.

[0078] On the other hand, NCR-MT520A (control unit 523) that has not established a radio connection with gNB200 may determine that access (connection establishment) to the gNB200 is not possible when the gNB200 does not broadcast the NCR support information (or broadcasts the NCR non-support information). Thereby, NCR-MT520A can establish a radio connection only with a gNB200 that can handle NCR-MT520A.

[0079] In addition, when gNB 200 is congested, gNB 200 may broadcast access control information for restricting access from UE 100. However, different from a normal UE 100, NCR-MT520A can also be regarded as an entity on the network side. Therefore, NCR-MT520A may ignore the access control information from gNB 200. For example, when NCR-MT520A (control unit 523) receives NCR support information from gNB 200, even if the gNB 200 is broadcasting access control information, it may perform operations for establishing a radio connection with the gNB 200. For example, NCR-MT520A (control unit 523) may not (or may ignore) execute UAC (Unified Access Control). Alternatively, for one or both of the AC / AI (Access Category / Access Identity) used in UAC, special values indicating that it is an access of NCR-MT may be used.

[0080] In step S12, NCR-MT520A (control unit 523) starts a random access procedure for gNB 200. In the random access procedure, NCR-MT520A (transmission unit 522) transmits a random access preamble (Msg1) and an RRC message (Msg3) to gNB 200. Also, in the random access procedure, NCR-MT520A (reception unit 521) receives a random access response (Msg2) and an RRC message (Msg4) from gNB 200.

[0081] In step S13, when establishing a radio connection with gNB200, NCR-MT520A (transmission unit 522) may transmit NCR-MT information indicating that the own UE is an NCR-MT to gNB200. For example, during the random access procedure with gNB200, NCR-MT520A (transmission unit 522) includes the NCR-MT information in a message for the random access procedure (e.g., Msg1, Msg3, Msg5) and transmits it to gNB200. Based on the NCR-MT information received from NCR-MT520A, gNB200 (control unit 230) recognizes that the accessed UE100 is NCR-MT520A, and for example, can remove NCR-MT520A from the access restriction target (i.e., accept the access). When the random access procedure is completed, NCR-MT520A transitions from the RRC idle state or the RRC inactive state to the RRC connected state.

[0082] In step S14, gNB200 (transmission unit 522) transmits a capability inquiry message for inquiring about the capabilities of NCR-MT520A to NCR-MT520A. NCR-MT520A (reception unit 521) receives the capability inquiry message.

[0083] In step S15, NCR-MT520A (transmission unit 522) transmits a capability information message including NCR capability information to gNB200. The capability information message may be an RRC message, for example, a UE Capability message. gNB200 (reception unit 220) receives the capability information message. Based on the received capability information message, gNB200 (control unit 230) grasps the capabilities of NCR device 500A.

[0084] In step S16, the gNB 200 (transmission unit 522) transmits a configuration message including various configurations related to the NCR device 500A to the NCR-MT 520A. The NCR-MT 520A (reception unit 521) receives the configuration message. The configuration message is a type of the above-mentioned downlink signaling. The configuration message may be an RRC message, for example, an RRC Reconfiguration message.

[0085] In step S17, the gNB 200 (transmission unit 522) transmits a control instruction specifying the operating state of the NCR-Fwd 510A to the NCR-MT 520A. The control instruction may be the above-mentioned NCR control signal (for example, L1 / L2 signaling). The NCR-MT 520A (reception unit 521) receives the control instruction. The NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A according to the control instruction.

[0086] In step S18, the NCR-MT 520A controls the NCR device 500A according to the above configuration (and control instruction). Note that the NCR-MT 520A may control the NCR device 500A autonomously without depending on the control instruction from the gNB 200. For example, the NCR-MT 520A may control the NCR device 500A autonomously based on the position of the UE 100 and / or the information received by the NCR-MT 520A from the UE 100.

[0087] (1.8) Beam sweeping FIG. 13 is a diagram for explaining beam sweeping according to an embodiment.

[0088] gNB 200 performs beam sweeping in which it sequentially switches beams in different directions while transmitting. At this time, gNB 200 transmits different SSBs for each beam. The SSB is periodically transmitted from gNB 200 into the cell as an SSB burst composed of a plurality of SSBs. Each of the plurality of SSBs in one SSB burst is assigned an SSB index which is an identifier. The SSBs are transmitted with beamforming in different directions respectively. The NCR device 500A (NCR-MT520A) reports to gNB 200 during the random access channel (RACH) procedure which direction of the beam had good reception quality. Specifically, the NCR device 500A (NCR-MT520A) transmits a random access preamble to gNB 200 on a random access channel (RACH) occasion associated with the SSB index for which the reception quality of the beam was good. As a result, gNB 200 can grasp the optimal beam for the NCR device 500A (NCR-MT520A).

[0089] Note that such an SSB may be transmitted in the initial BWP (initial DL BWP). When the NCR device 500A (NCR-MT520A) is in the RRC connected state, a dedicated BWP may be set and activated for the NCR device 500A (NCR-MT520A). In the dedicated BWP, a channel state information reference signal (CSI-RS) may be used as a reference signal instead of the SSB. In the following, on the premise that there is a one-to-one relationship between the beam and the SSB (specifically, the SSB index), an example in which the beam information for identifying the beam is the SSB index will be mainly described. However, the beam may be associated with the CSI-RS. The beam information for identifying the beam may be the CSI-RS index.

[0090] (1.9) Beam Unit Access Control FIG. 14 is a diagram for explaining beam unit access control according to an embodiment.

[0091] By installing the NCR device 500A inside the cell, it is possible to expand the coverage of the cell by the NCR device 500A. Therefore, the number of UEs 100 accommodated in the cell also increases, and the cell may become congested and the resources of the cell may become scarce.

[0092] In the example of FIG. 14, the NCR device 500A (NCR-Fwd 510A) performs relay transmission for the beam #1 formed by the gNB 200. The beam #1 is associated with the SSB #1 (where "#1" represents the SSB index). The UEs 100a and 100b receive the beam #1 formed by the NCR device 500A (NCR-Fwd 510A). The UE 100c receives the beam #2 associated with the SSB #2. The UE 100c receives the beam #3 associated with the SSB #3.

[0093] Here, access control is specified as a mechanism for restricting access to the cell of the gNB 200 when the load of the gNB 200 increases. In general access control, the gNB 200 sets the parameter (cellBarred) in the master information block (MIB) broadcast in its own cell to a value indicating access prohibited (barred). When a UE 100 in the RRC idle state or the RRC inactive state discovers a cell that broadcasts such an MIB, it determines that access (random access) to the cell is prohibited and searches for other cells. In such general access control, there is a problem that access of all UEs 100 is restricted.

[0094] In the example of FIG. 14, the load of the gNB 200 can be reduced by controlling the gNB 200 to turn off the NCR device 500A. However, there is a problem that the already connected UEs 100a and 100b need to perform beam recovery or the like, and communication becomes impossible if they cannot find other appropriate beams. Therefore, in the embodiment, it is possible to perform access control in units of beams. This makes it possible to perform fine-grained access control.

[0095] FIG. 15 is a diagram showing an example of beam unit access control according to an embodiment.

[0096] In the embodiment, the gNB 200 forms a plurality of beams in one cell by beam sweeping. When the gNB 200 subjects only some of the plurality of beams to access control, the gNB 200 broadcasts first information indicating that access control is performed in beam units in the some of the beams. Thereby, it is possible to perform access control in beam units instead of cell units.

[0097] The first information is information defined separately from second information (cellBarred) indicating the presence or absence of access control in cell units. For example, the first information is 1-bit information in which a first value (for example, "1") is set when access control is performed in beam units, and a second value (for example, "0") is set when access control is not performed in beam units. The first information is also referred to as "beamBarred", the first value is also referred to as "barred", and the second value is also referred to as "notBarred".

[0098] For example, the gNB 200 transmits an MIB including information indicating the first information (beamBarred). Since the MIB is included in the SSB, the UE 100 that has received the beam (SSB) can grasp whether access to the beam is possible based on the first information (beamBarred) in the MIB included in the beam (SSB).

[0099] The gNB 200 may transmit an MIB including the first information (beamBarred) in which barred is set and second information indicating that access control is not performed in cell units in the beam to be access-controlled. Thereby, the UE 100 that has received the MIB in the beam of the cell can grasp that access to the cell is not restricted but access to the beam is restricted, and can search for other beams of the cell.

[0100] The second piece of information (cellBarred) is general access control information. When access control is performed on a cell-by-cell basis, the second piece of information is set to a first value (e.g., "1"), and when access control is not performed on a cell-by-cell basis, the second piece of information is set to a second value (e.g., "0"), which is 1-bit information. The second piece of information is also referred to as "cellBarred", the first value is also referred to as "barred", and the second value is also referred to as "notBarred".

[0101] When gNB200 targets its own cell for overall access control, it may broadcast the second piece of information indicating that access control is performed on a cell-by-cell basis in a plurality of beams. For example, gNB200 may transmit the MIB including cellBarred with barred set in all beams of its own cell.

[0102] The NCR device 500A that performs relay transmission of a beam whose access is restricted transfers the first piece of information (beamBarred) from gNB200. Thereby, the UE100 that receives the beam formed by the NCR device 500A can determine whether access to the beam is possible based on the first piece of information (beamBarred) received from the NCR device 500A.

[0103] Note that the NCR device 500A (NCR-MT520A) may be permitted to access gNB200 regardless of cellBarred and beamBarred. That is, the NCR device 500A (NCR-MT520A) may be able to ignore cellBarred and beamBarred. For example, the NCR device 500A (NCR-MT520A) may be permitted to access gNB200 even when it receives cellBarred with barred set or beamBarred with barred set from gNB200.

[0104] Alternatively, the NCR device 500A (NCR-MT520A) can ignore cellBarred, but beamBarred may be applied. For example, when the NCR device 500A (NCR-MT520A) receives beamBarred with barred set from the gNB 200, access to the gNB 200 may be prohibited.

[0105] FIG. 16 is a diagram showing an operation example of the gNB 200 regarding beam unit access control.

[0106] In step S101, the gNB 200 that forms a plurality of beams in its own cell determines whether to perform cell unit access control. If it is determined to perform cell unit access control (step S101: YES), in step S102, the gNB 200 transmits the MIB including cellBarred with barred set in all beams of its own cell.

[0107] If it is determined not to perform cell unit access control (step S101: NO), in step S103, the gNB 200 determines whether to perform beam unit access control, that is, access control for a specific beam among the plurality of beams in its own cell. If it is determined to perform beam unit access control (step S103: YES), in step S104, the gNB 200 transmits the MIB including beamBarred with barred set only in the specific beam.

[0108] FIG. 17 is a diagram showing an operation example of the UE 100 regarding beam unit access control. Here, the UE 100 may be in the RRC idle state or the RRC inactive state.

[0109] In step S201, the UE100 that receives the MIB transmitted by the cell's beam determines whether it has received the MIB including cellBarred with barred set. If it is determined that the MIB including cellBarred with barred set has been received (step S201: YES), in step S202, the UE100 determines that access to the cell is prohibited and performs cell reselection processing to another cell.

[0110] On the other hand, if it is determined that the MIB including cellBarred with notBarred set has been received (step S201: NO), in step S203, the UE100 determines whether it has received the MIB including beamBarred with barred set. If it is determined that the MIB including beamBarred with barred set has been received (step S203: YES), in step S204, the UE100 determines that access to the beam is prohibited and performs processing to search for other beams of the cell. That is, the UE100 refrains from accessing via the SSB including the MIB indicating the access prohibition. Here, the UE100 may exclude the beam (SSB) from the candidates and search for another beam (SSB). The UE100 may be prohibited from accessing only for a certain period after receiving the MIB. The certain period may be broadcast by the gNB200 in SIB or the like. The certain period may be determined in advance in the system specification. In that case, after the elapse of the certain period, the UE100 may receive the beam (SSB) again and determine whether access is possible.

[0111] If it is determined that the MIB including beamBarred with notBarred set has been received (step S203: NO), in step S205, the UE100 determines that access to the gNB200 via the beam (SSB) is possible.

[0112] In the above description, an example of adding beamBarred to the MIB has been described. However, beamBarred may be added to, for example, System Information Block type 1 (SIB1). For example, gNB200 may set "beamBarred=barred" for SIB1 transmitted with the beam in the direction of the NCR device 500A, and set "beamBarred=notBarred" for SIB1 transmitted with the beam in other directions.

[0113] (1.10) Inter-cell cooperative operation Assuming that the NCR device 500A is installed at the cell edge, the NCR device 500A can be a source of interference to adjacent cells. In the embodiment, the first network node that manages the first cell controls the NCR device 500A (relay device) that relays radio signals between the first network node and the UE100 in the first cell. The first network node communicates control state information regarding the control state of the NCR device 500A with the second network node that manages the second cell adjacent to the first cell. Thereby, it becomes possible to cooperate between cells, and the occurrence of interference caused by the NCR device 500A can be suppressed.

[0114] The first network node may be the first DU connected to the CU. The second network node may be the second DU connected to the CU. The first DU may communicate control state information with the second DU via the CU.

[0115] Alternatively, the first network node may be the first gNB. The second network node may be the second gNB connected to the first gNB via the base station interface (Xn interface). The first gNB may communicate control state information with the second DU via the Xn interface.

[0116] The first network node may notify the second network node of control state information indicating the control state of the NCR device 500A under the control of the first network node. Prior to such notification, the second network node may send an inquiry to the first network node to request notification of the control state information.

[0117] The second network node may notify the first network node of control state information indicating the control state of the NCR device 500A desired by the second network node.

[0118] (1.10.1) First operation example of inter-cell cooperative operation FIG. 18 is a diagram for explaining a first operation example of inter-cell cooperative operation according to an embodiment. In the first operation example, the first network node is DU250a (the first DU), and the second network node is DU250b (the second DU). DU250a (the first DU) communicates the control state information of the NCR device 500A with DU250b (the second DU) via the CU260.

[0119] In the example of FIG. 18, the NCR device 500A installed at the cell edge of cell C1 may be a source of interference to cell C2. Here, it is assumed that the gNB200 is functionally split into DU250 (in the illustrated example, two DUs 250a and 250b) and CU260, and if the NCR device 500A is controlled by the gNB200 using DCI or MAC CE, it is considered that the DU250a is actually controlling the NCR device 500A. Since the RRC connection of the NCR device 500A (NCR-MT520A) terminates at the CU260, the CU260 manages the RRC measurement reports and the like of the NCR device 500A (NCR-MT520A).

[0120] Cell C1 is managed by DU250a, cell C2 is managed by DU250b, and DU250a and 250b are managed by the same CU260. That is, gNB200 is composed of DU250a and 250b and CU260. Each of DU250a and 250b is connected to CU260 via the F1 interface. Since the NCR device 500A is installed at the cell edge of cell C1, cell C1 is the serving cell of the NCR device 500A (NCR-MT520A). The NCR device 500A relays the radio signal transmitted between cell C1 (DU250a) and UE100.

[0121] FIG. 19 is a diagram showing a first operation example of inter-cell cooperative operation according to an embodiment. The NCR device 500A (NCR-MT520A) has established an RRC connection with the CU260 via the DU250a (serving cell) (step S301). In the drawings referred to in the following embodiments, steps that are not essential are indicated by dashed lines.

[0122] In step S302, the DU250a starts controlling the NCR device 500A. The control of the NCR device 500A is performed by the above-described NCR control signal. In step S303, the NCR-MT520A of the NCR device 500A controls the NCR-Fwd510A according to the NCR control signal received from the DU250a.

[0123] In step S304, the DU250b may inquire of the CU260 on the F1 interface whether there is a connection to the NCR device 500A. The inquiry may include the cell ID of cell C2 managed by the DU250b. The cell ID is used by the CU260 to determine adjacent cells. The inquiry may also include the RSRP threshold value for the CU260 to determine adjacent cells.

[0124] In step S305, CU260 may inquire DU250a whether there is a connection to NCR device 500A. CU260 may notify DU250a of the identifier of NCR device 500A necessary for reporting control state information. CU260 may determine whether NCR device 500A is at the cell edge of cell C1 based on the serving cell measurement result included in the RRC measurement report from NCR device 500A (NCR-MT520A). CU260 may determine near which neighboring cell NCR device 500A is located based on the neighboring cell measurement result included in the RRC measurement report.

[0125] In step S306, DU250a transmits a notification including information indicating the control state of NCR device 500A (control state information) to CU260 on the F1 interface. For example, the control state information includes at least one of the SSB index of the beam relayed by NCR device 500A, the control value of NCR device 500A (such as transmission weight), and the cell ID of the serving cell C1 to which NCR device 500A is connected. The control value of NCR device 500A is a control value corresponding to the above-mentioned NCR control signal and may be a control value for each slot. The control value may be the current control value.

[0126] In step S307, CU260 transmits the notification including the control state information from DU250a to DU250b on the F1 interface. The notification may include the identifier of NCR device 500A associated with the control state information and / or the cell ID of serving cell C1.

[0127] In step S308, DU250b determines the influence of the interference of NCR device 500A based on the control state information from CU260 and the communication quality of its own cell C2.

[0128] In step S309, DU250b may transmit a notification including information indicating a desired or undesired control state (control state information) of the NCR device 500A to CU260 on the F1 interface. The control state information may be information on a recommended or non-recommended transmission weight (beam, SSB index, or angle). The control state information may be ON / OFF of relay transmission. The control state information may be a desired value of transmission power (indicating that it should be lowered or by how many dB). The notification may include at least one of timing information (such as slot number), an identifier of the NCR device 500A, and a cell ID of the serving cell C1, which is associated with the control state information.

[0129] In step S310, CU260 may transmit a notification including control request information from DU250b to DU250a on the F1 interface.

[0130] (1.10.2) Second operation example of inter-cell coordination operation FIG. 20 is a diagram for explaining a second operation example of inter-cell coordination operation according to an embodiment. In the second operation example, the first network node is gNB200a (the first gNB), and the second network node is gNB200b (the second gNB). gNB200a (the first gNB) communicates control state information with gNB200b (the second gNB) via the Xn interface. In FIG. 20, an example is shown in which gNB200a is functionally split into DU250a and CU260a, and gNB200b is functionally split into DU250b and CU260b, but it does not have to be functionally split.

[0131] FIG. 21 is a diagram showing a second operation example of inter-cell coordination operation according to an embodiment. The NCR device 500A (NCR-MT520A) has established an RRC connection with gNB200a (step S401). In the description of the second operation example, the description of operations overlapping with those of the above-described first operation example is omitted.

[0132] In step S402, gNB200a starts controlling the NCR device 500A. The control of the NCR device 500A is performed by the above-described NCR control signal. In step S403, the NCR-MT 520A of the NCR device 500A controls the NCR-Fwd 510A according to the NCR control signal received from gNB200a.

[0133] In step S404, gNB200b may inquire gNB200a whether there is a connection to the NCR device 500A. The inquiry may include the cell ID of cell C2 managed by gNB200b. The cell ID is used by gNB200a to perform adjacent cell determination. The inquiry may also include the RSRP threshold for gNB200a to perform adjacent cell determination.

[0134] In step S405, gNB200a transmits a notification including information indicating the control state of the NCR device 500A (control state information) to gNB200b on the Xn interface. For example, the control state information includes at least one of the SSB index of the beam relayed by the NCR device 500A, the control value of the NCR device 500A (such as the transmission weight), and the cell ID of the serving cell C1 to which the NCR device 500A is connected. The control value of the NCR device 500A is a control value corresponding to the above-described NCR control signal and may be a control value for each slot. The control value may be the current control value.

[0135] In step S406, gNB200b determines the influence of the interference of the NCR device 500A based on the control state information from gNB200a and the communication quality of its own cell C2.

[0136] In step S407, gNB200b may transmit a notification including information indicating a desired or undesired control state (control state information) to gNB200a on the Xn interface to the NCR device 500A. The control state information may be information on a recommended or non-recommended transmission weight (beam, SSB index, or angle). The control state information may be ON / OFF of relay transmission. The control state information may be a desired value of transmission power (indicating that it should be decreased or by how many dB it should be decreased). The notification may include at least one of timing information (such as slot number), an identifier of the NCR device 500A, and a cell ID of the serving cell C1, which is associated with the control state information.

[0137] (2) Second Embodiment Next, the second embodiment will be mainly described in terms of differences from the above-described first embodiment. The outline of the mobile communication system 1 and the configuration of the gNB200 according to the second embodiment are the same as those of the first embodiment described above.

[0138] As shown in FIG. 22, the relay device according to the second embodiment is a RIS (Reconfigurable Intelligent Surface) device 500B that changes the propagation direction of incident radio waves (radio signals) by reflection or refraction. "NCR" in the above-described first and second embodiments can be read as "RIS".

[0139] The RIS is a type of repeater (hereinafter, also referred to as "RIS-Fwd") that can perform beamforming (directivity control) in the same manner as the NCR by changing the characteristics of the metamaterial. In the case of the RIS, the range (distance) of the beam may also be changeable by controlling the reflection direction and / or refraction direction of each unit element. For example, it may be configured to control the reflection direction and / or refraction direction of each unit element and direct the beam towards a nearby UE or a distant UE.

[0140] The RIS device 500B has a new UE (hereinafter referred to as "RIS-MT") 520B which is a control terminal for controlling the RIS-Fwd510B. The RIS-MT 520B controls the RIS-Fwd510B in cooperation with the gNB200 by establishing a wireless connection with the gNB200 and performing wireless communication with the gNB200. The RIS-Fwd510B may be a reflective RIS. Such a RIS-Fwd510B changes the propagation direction of the incident radio wave by reflecting the incident radio wave. Here, the reflection angle of the radio wave can be variably set. The RIS-Fwd510B reflects the radio wave incident from the gNB200 toward the UE100. The RIS-Fwd510B may be a transmissive RIS. Such a RIS-Fwd510B changes the propagation direction of the incident radio wave by refracting the incident radio wave. Here, the refraction angle of the radio wave can be variably set.

[0141] FIG. 23 is a diagram showing a configuration example of RIS-Fwd510B and RIS-MT520B according to the second embodiment. The RIS-MT520B includes a receiving unit 521, a transmitting unit 522, and a control unit 523. Such a configuration is the same as that of the first embodiment described above. The RIS-Fwd510B includes a RIS 511B and a RIS control unit 512B. The RIS 511B is a metasurface configured using metamaterials. For example, the RIS 511B is configured by arranging very small structures in an array with respect to the wavelength of radio waves, and by making the structures have different shapes depending on the placement location, it is possible to arbitrarily design the direction of the reflected wave and / or the beam shape. The RIS 511B may be a transparent dynamic metasurface. The RIS 511B is configured by stacking a transparent glass substrate on a transparent metasurface substrate in which a large number of small structures are regularly arranged. By slightly moving the stacked glass substrate, it is possible to dynamically control three modes: a mode in which incident radio waves are transmitted, a mode in which part of the radio waves are transmitted and part are reflected, and a mode in which all radio waves are reflected. The RIS control unit 512B controls the RIS 511B according to the RIS control signal from the control unit 523 of the RIS-MT520B. The RIS control unit 512B may include at least one processor and at least one actuator. The processor decodes the RIS control signal from the control unit 523 of the RIS-MT520B and drives the actuator according to the RIS control signal.

[0142] (3) Other Embodiments In the above embodiment, an example in which the gNB 200 controls the NCR device 500A has been described. However, the NCR device 500A (NCR-MT520A) may autonomously control the NCR-Fwd510A based on the settings from the gNB 200. FIG. 24 is a diagram showing an example of beam sweeping according to another embodiment. The gNB 200 transmits a plurality of beams (beams of SSB3 to SSB5 in the illustrated example) in the direction of the NCR device 500A with the same transmission weight for the backhaul link. The NCR device 500A (NCR-Fwd510A) autonomously transmits the plurality of beams (beams of SSB3 to SSB5) in different directions with different transmission weights for the access link. Under such a premise, the NCR device 500A (NCR-Fwd510A) may appropriately notify the gNB 200 of the operating state of the NCR-Fwd510A and share the operating state information of the NCR-Fwd510A with the gNB 200.

[0143] Each of the above operation flows is not limited to being implemented separately and independently, and two or more operation flows can be combined and implemented. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow. In each flow, it is not necessarily required to execute all steps, and only some steps may be executed.

[0144] In the above embodiment, an example in which the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB). Further, the base station may be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may be a DU (Distributed Unit) of the IAB node.

[0145] A program may be provided that causes a computer to execute each process performed by UE100 (NCR-MT520A, RIS-MT520B) or gNB200. The program may be recorded on a computer-readable medium. By 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-transitory recording medium. The non-transitory recording medium is not particularly limited, but may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Also, a circuit that executes each process performed by UE100 or gNB200 may be integrated, and at least a part of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0146] As used in this disclosure, the terms "based on" and "depending on / in response to" do not mean "only based on" or "only in response to" unless otherwise specified. The term "based on" means both "only based on" and "at least partially based on". Similarly, the term "depending on" means both "only depending on" and "at least partially depending on". The terms "include", "comprise", and their variants do not mean only including the listed items, but mean that they may include only the listed items or may further include additional items in addition to the listed items. Also, the term "or" used in this disclosure is not intended to be an exclusive disjunction. Furthermore, any reference to elements using designations such as "first", "second", etc. used in this disclosure does not generally limit the quantity or order of those elements. These designations can be used in this specification as a convenient way to distinguish between two or more elements. Therefore, a reference to a first and a second element does not mean that only two elements can be employed there or that the first element must precede the second element in some form. In this disclosure, for example, when articles are added by translation, such as a, an, and the in English, these articles are assumed to include plural ones unless the context clearly indicates otherwise.

[0147] As described above in detail with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist.

[0148] This application claims the priority of U.S. Provisional Application No. 63 / 395,929 (filed on August 8, 2022), and all of its content is incorporated herein by reference.

[0149] (4) Supplementary Note The features regarding the above-described embodiments are noted.

[0150] (Appendix 1) A communication method used in a mobile communication system, a step in which a base station forms a plurality of beams in one cell by beam sweeping; when the base station subjects only some of the plurality of beams to access restriction, a step of broadcasting, in the some of the beams, first information indicating that access restriction is performed in beam units. Communication method.

[0151] (Appendix 2) further comprising a step of broadcasting, in the plurality of beams, second information indicating that access restriction is performed in cell units when the base station subjects the entire cell to access restriction; the first information is information defined separately from the second information The communication method according to Appendix 1.

[0152] (Appendix 3) the transmitting step includes a step of transmitting a master information block including the first information The communication method according to Appendix 1 or 2.

[0153] (Appendix 4) the transmitting step includes a step of transmitting the master information block including the first information and second information indicating that access restriction is not performed in cell units The communication method according to Appendix 3.

[0154] (Appendix 5) a relay device that performs relaying transmission of the some of the beams further includes a step of relaying the first information from the base station The communication method according to any one of Appendices 1 to 4.

[0155] (Appendix 6) The user equipment that receives the partial beam further includes a step of refraining from accessing the partial beam in response to the reception of the first information and searching for other beams of the cell. The communication method according to any one of Appendices 1 to 5.

[0156] (Appendix 7) A communication method used in a mobile communication system, A step in which a first network node that manages a first cell controls a relay device that relays a radio signal between the first network node and a user equipment in the first cell; The step in which the first network node communicates control state information regarding the control state of the relay device with a second network node that manages a second cell adjacent to the first cell. Communication method.

[0157] (Appendix 8) The first network node is a first distributed unit connected to an aggregation unit, The second network node is a second distributed unit connected to the aggregation unit, The step of communicating includes a step in which the first distributed unit communicates the control state information with the second distributed unit via the aggregation unit. The communication method according to Appendix 7.

[0158] (Appendix 9) The first network node is a first base station, The second network node is a second base station connected to the first base station via an interface between base stations, The step of communicating includes a step in which the first base station communicates the control state information with the second distributed unit via the interface between base stations. The communication method according to Appendix 7.

[0159] (Appendix 10) The step of communicating includes the step of notifying, from the first network node to the second network node, the control state information indicating the control state of the relay device under the control of the first network node. The communication method according to any one of Appendices 7 to 9.

[0160] (Appendix 11) The method further includes the step of making an inquiry from the second network node to the first network node to request notification of the control state information. The communication method according to Appendix 10.

[0161] (Appendix 12) The step of communicating includes the step of notifying, from the second network node to the first network node, the control state information indicating the control state of the relay device desired or not desired by the second network node. The communication method according to any one of Appendices 7 to 11.

[0162] (5) Appendix Introduction RAN#94e reached an agreement on new study items regarding a network-controlled repeater (NCR). The objectives of this study are as follows.

[0163] Examine and define the side control information required for a network-controlled repeater as follows (including the assumption of maximum transmission power). - Beamforming information - Timing information for aligning the transmission and reception boundaries of the network-controlled repeater - Information regarding UL-DL TDD configuration - ON-OFF information for efficient interference management and energy efficiency improvement - Power control information for efficient interference management (as the second priority) Examine and define L1 / L2 signaling (including its configuration) for transmitting side control information.

[0164] Consider the following aspects regarding the management of network-controlled repeaters. - Identification and approval of network-controlled repeaters. Note 2: Adjustment with SA3 may be required.

[0165] In this appendix, the initial issues of RAN2 regarding NCR are discussed.

[0166] Discussion NCR model According to the SID, the scenarios and assumptions are described as follows.

[0167] The study on NR network-controlled repeaters is to focus on the following scenarios and assumptions. - The network-controlled repeater is an in-band RF repeater used to expand the network coverage of FR1 and FR2 bands. The study is underway on the possibility that the deployment of FR2 may be prioritized in both outdoor-to-indoor (O2I) scenarios. - Limited to single-hop stationary network-controlled repeaters - The network-controlled repeater is transparent to the UE - The network-controlled repeater can simultaneously maintain links with the gNB and the UE Note 1: Cost efficiency is an important consideration for network-controlled repeaters.

[0168] RAN1#109e agreed on the NCR model as follows.

[0169] Agreements The model of the network-controlled repeater in TR38.867 is shown in Figure 25 and below. · NCR-MT is defined as a functional entity that communicates with the gNB via a control link (C-link). This enables information exchange (e.g., side control information). The C-link is based on the NR Uu interface. Note: The side control information is for at least the control of NCR-FW. · NCR-Fwd is defined as a functional entity that performs amplification and transfer of UL / DL RF signals between the gNB and the UE via the backhaul link and the access link. The operation of NCR-Fwd is controlled according to the side control information received from the gNB.

[0170] According to the above description, since NCR-Fwd is an in-band RF repeater, it should have no impact on RAN2.

[0171] Finding 1: NCR-Fwd is an RF repeater and is outside the scope of RAN2.

[0172] On the other hand, NCR-MT maintains a control link with the gNB and communicates side control information. NCR-MT can be considered a special UE type similar to IAB-MT. That is, it is natural to think that support for protocols such as NAS, RRC, PDCP, RLC, MAC, and PHY is required. As a starting point, IAB-MT is considered a good reference for modeling NCR-MT. However, since the BAP sublayer assumes only "single-hop stationary network control type repeaters", it is obvious that it is not required for NCR-MT, and the control link coverage extension should be performed by other means such as the use of FR1 or the use of RF repeaters.

[0173] Proposal 1: As a starting point, RAN2 should consider IAB-MT as a reference for the NCR-MT model, and the BAP sublayer is not supported in NCR-MT.

[0174] The IAB-MT can transmit and receive its own traffic, such as OAM traffic. Since NCR may implement the OAM function, the same principle applies to the NCR-MT. Therefore, the NCR-MT needs to support not only the SRB (side control information, RRC configuration, NAS connection, etc.) but also the DRB (its own traffic, etc.), and the establishment of the DRB may be optional.

[0175] Proposal 2: The NCR-MT should agree to support both the SRB and the DRB.

[0176] As shown in Figure 26, the instructions from the gNB (e.g., side control information) are considered to be used by the NCR-MT for the control of NCR-Fwd (e.g., beamforming, ON / OFF control, power control, etc.) via the internal interface, regardless of whether such an internal interface is specified.

[0177] Finding 2: The NCR-MT receives instructions from the gNB (e.g., via side control information) and controls the NCR-Fwd accordingly.

[0178] Aspects related to NCR management Identification, authentication, access control According to the SID, RAN2 is responsible for considering the management plane.

[0179] Consider the following aspects related to the management of the network-controlled repeater. - Identification and authentication of the network-controlled repeater Note 2: Adjustment with SA3 may be required.

[0180] When considering the IAB-MT as a reference as in Proposal 1, since the NCR is regarded as a network node, the same access control mechanism is considered applicable to the NCR-MT.

[0181] · The gNB provides SIB indication to permit access of the NCR-MT. This is something like the IAB-Support IE in SIB1. · The NCR-MT ignores the Cell Barred IE and Intra-Freq Reselection IE in the MIB. · The NCR-MT ignores the IEs related to the following reserved cells. - Cell Reserved For Future Use IE - Cell Reserved For Other Use IE (Regarding cell barring decision) - Cell Reserved For Operator Use IE (When the NCR-MT supports NPN) · The NCR-MT sends an NCR indication at the completion of RRC setup, like the IAB Node Indication IE.

[0182] Proposal 3: When NCR is considered as a network node, RAN2 should agree to reuse the access control mechanism of the IAB-MT. That is, the gNB provides SIB indication, and the NCR-MT ignores the IEs related to cell barring and cell reservation.

[0183] If the NCR-MT is regarded as something similar to the IAB-MT from the perspective of RAN2, RAN2 may assume that the upper layer mechanism of the IAB-MT is also reused for the NCR-MT. For example, it may be reused for authentication.

[0184] Finding 3: RAN2 can assume that the upper layer mechanism of the IAB-MT is also reused for the NCR-MT. For example, it is the reuse in terms of authentication.

[0185] NCR's capability signal Another issue related to management is that since NCR-Fwd is an RF repeater, i.e., it has no protocol support, how can the gNB recognize the functions of NCR-Fwd such as the operating frequency, the number and resolution of beamforming, the output power and dynamic range, etc. It is very simple for NCR-MT to notify the gNB of the capabilities of the connected NCR-Fwd in addition to its own (i.e., NCR-MT) capabilities.

[0186] Proposal 4: RAN2 should agree that NCR-MT notify the gNB of the capabilities of NCR-Fwd. Further consideration is needed for the capabilities to be reported.

[0187] Multi-beam NCR As shown in Figure 27, it is also worth considering whether NCR can process multiple beams. This is expected to improve spectral efficiency, enhance coverage, and provide flexibility in scheduling for multiple UEs.

[0188] Simple RF repeaters do not have resource block selectivity and amplify and transfer all signals within the system bandwidth with a single weight. On the other hand, some advanced RF repeaters may manage multiple beams for multiple UEs. Therefore, it is important for Rel-18NCR to support the implementation of such advanced RF repeaters.

[0189] Proposal 5: RAN2 should agree that the gNB manage NCRs that can process multiple beams simultaneously for different UEs.

[0190] If multi-beam NCR is supported, from the perspective of RAN2, there may be discussions on whether one NCR node (or one NCR-MT) can support multiple NCR-Fwds. Similarly, it may also be additionally considered whether one NCR-Fwd can control multiple "antenna sets". These options are shown in Figure 28.

[0191] Multiple NCR-Fwds or multiple antenna sets can process different beams for different UEs using different resource blocks within the same slot (as shown in Figure 27). In the case of multiple NCR-Fwds, the NCR needs to process different weights indicated by the gNB for each NCR-Fwd simultaneously.

[0192] As another possible scenario, it is conceivable that the NCR is controlled by multiple gNBs. For example, when the NCR is deployed at the cell edge. In this case, multiple NCR-Fwds are required to process different beams for different access links belonging to different gNBs.

[0193] These cases may affect the management of the NCR and the design of side control information. Therefore, RAN2 needs to discuss a management model to permit different implementations of multi-beam NCRs.

[0194] Note: RAN1 determines whether multiple NCR-Fwds are installed in a common location (e.g., for the gain of spatial diversity). Even if multiple Fwds are not installed in a common location, RAN1 should assume that the control link and the backhaul link share the same radio channel conditions. This is suggested by the decision in RAN#96.

[0195] Proposal 6: RAN2 should discuss a management model for repeaters with multiple beams. For example, consider whether one NCR-MT can control multiple NCR-Fwds, or whether one NCR-Fwd can support multiple antenna sets.

[0196] Side control information RAN1 is discussing the overall concept and functions of side control information such as beam information, TDD UL / DL configuration, DL reception and UL transmission timing, and ON-OFF information. From the perspective of RAN2, it is assumed that dynamic and semi-static controls may be indicated by DCI and MAC CE (or a combination of these), respectively. Furthermore, static configuration should be performed by RRC. Regarding the detailed design of side control information, RAN2 needs to wait for the progress of RAN1.

[0197] Finding 4: Side control information may need to extend DCI, MAC CE, and / or RRC signaling. RAN2 needs to wait for further progress of RAN1.

[0198] Assumptions regarding deployment At RAN#96, support for multiple frequencies was discussed, but it was decided to limit the operating frequency of the control link in the same way as the backhaul link.

[0199] RAN Chair: The RAN1 study is planned to focus only on in-band.

[0200] It is considered that the control link procedure is intended to be simplified by leveraging the same channel conditions as the backhaul link.

[0201] Finding 5: When the control link and the backhaul link operate at the same frequency, the radio channel conditions are the same.

[0202] On the other hand, it is also worth considering whether NCR-MT can support carrier aggregation (CA) and dual connectivity (DC). For example, NCR-MT may set up an SCell (for side control information) in FR2 with the same frequency as the PCell (for RRC connection) in FR1, as shown in Figure 29.

[0203] The CA / DC configuration of NCR-MT is considered not to violate the RAN preliminary determination as long as the SCell for the control link operates on the same frequency as NCR-Fwd for the backhaul link. Furthermore, the robust RRC connection in FR1 / PCell brings various advantages considering that NCR is a network node. This is very similar to the CP / UP split configuration specified in IAB.

[0204] Proposal 7: RAN2 should consider the possibility that NCR-MT is configured with carrier aggregation (CA) or dual connectivity (DC). At least one SCell should be configured to operate on the same frequency as NCR-Fwd.

Explanation of symbols

[0205] 1: Mobile communication system 100: UE 200: gNB 210: Transmitter 220: Receiver 230: Control unit 240: Backhaul communication unit 500A: NCR device 500B: RIS device 511A: Radio unit 511a: Antenna unit 511b: RF circuit 511c: Directional control unit 512A: NCR control unit 512B: RIS control unit 521: Receiver 522: Transmitter 523: Control unit 530: Interface

Claims

1. A communication method, comprising: a base station broadcasting relay device support information indicating that the base station supports a control terminal included in a relay device; the control terminal determining, in response to receiving the relay device support information, that access to the base station is permitted; when the base station further broadcasts information regarding a reserved cell indicating a cell reserved for a specific use, the control terminal ignoring the information regarding the reserved cell. The communication method.

2. A relay device having a repeater and a control terminal, wherein the control terminal includes a receiving unit that receives relay device support information indicating that the control terminal is supported, which is broadcast from a base station; a control unit that determines, in response to receiving the relay device support information, that access to the base station is permitted; and when the receiving unit receives information regarding a reserved cell indicating a cell reserved for a specific use, which is further broadcast from the base station, the control unit ignores the information regarding the reserved cell. The relay device.

3. A system including a base station and a relay device having a repeater and a control terminal, wherein the base station includes a transmitting unit that broadcasts relay device support information indicating that the control terminal is supported; the transmitting unit further broadcasts information regarding a reserved cell indicating a cell reserved for a specific use; the control terminal includes a receiving unit that receives the relay device support information broadcast from the base station; a control unit that determines, in response to receiving the relay device support information, that access to the base station is permitted; and when the receiving unit receives the information regarding the reserved cell further broadcast from the base station, the control unit ignores the information regarding the reserved cell. The system.

4. In a relay device having a repeater and a control terminal, a process of receiving relay device support information indicating that the control terminal is supported, which is broadcast from a base station; a process of determining, in response to receiving the relay device support information, that access to the base station is permitted; When receiving information regarding a reserved cell indicating a cell reserved for a specific use, which is further broadcast from the base station, execute a process of ignoring the information regarding the reserved cell. Program. **Claim 5** A chipset for a relay device having a repeater and a control terminal, a process of receiving relay device support information indicating support for the control terminal, which is broadcast from a base station, a process of determining that access to the base station is permitted in response to the reception of the relay device support information, when receiving information regarding a reserved cell indicating a cell reserved for a specific use, which is further broadcast from the base station, execute a process of ignoring the information regarding the reserved cell. Chipset.

Images