COMMUNICATION METHOD, RELAY DEVICE, AND NETWORK NODE

Abstract

This communication method, which uses a relay device in a wireless communication system, comprises: a step in which a repeater, included in the relay device, relays a wireless signal of a prescribed frequency transmitted between a base station and a user device; and a step in which a control terminal included in the relay device performs wireless communication with the base station and controls the repeater. In the control terminal, a plurality of serving cells, which include a cell corresponding to the prescribed frequency, are configured by the base station.

Description

Communication method, relay device, and base station

[0001] The present disclosure relates to a communication method for use in a mobile communication system.

[0002] In recent years, fifth-generation (5G) mobile communication systems have been attracting attention. NR (New Radio), a radio access technology of 5G systems, is capable of wideband transmission using higher frequency bands than LTE (Long Term Evolution), a fourth-generation radio access technology.

[0003] Radio signals (radio waves) in high-frequency bands such as millimeter waves or terahertz waves have a high degree of directionality, which poses a problem of reducing the coverage of base stations. To solve this problem, repeater devices, which are a type of relay device that relays radio signals between base stations and user devices and can be controlled from a network, have attracted attention (see, for example, Non-Patent Document 1). Such repeater devices can, for example, amplify radio signals received from base stations and transmit them using directional transmission, thereby expanding the coverage of base stations while suppressing interference.

[0004] 3GPP contribution: RP-213700, “New SI: Study on NR Network-controlled Repeaters”

[0005] A communication method according to a first aspect is a communication method using a relay device in a mobile communication system, comprising the steps of: a repeater included in the relay device relaying a radio signal of a predetermined frequency transmitted between a base station and a user device; and a control terminal included in the relay device controlling the repeater by wirelessly communicating with the base station, wherein the base station sets a plurality of serving cells in the control terminal, including a cell corresponding to the predetermined frequency.

[0006] A relay device according to a second aspect is a relay device used in a mobile communication system, and includes a repeater that relays a radio signal of a predetermined frequency transmitted between a base station and a user device, and a control terminal that controls the repeater by wirelessly communicating with the base station. The control terminal is configured by the base station with a plurality of serving cells including a cell corresponding to the predetermined frequency.

[0007] A base station according to a third aspect is a base station used in a mobile communication system, and includes a communication unit that performs wireless communication with a control terminal that controls a repeater that relays a radio signal of a predetermined frequency transmitted between the base station and a user device, and a control unit that sets a plurality of serving cells, including a cell corresponding to the predetermined frequency, in the control terminal.

[0008] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. FIG. 1 is a diagram illustrating a protocol stack configuration of a radio interface of a user plane that handles data. FIG. 2 is a diagram illustrating a protocol stack configuration of a radio interface of a control plane that handles signaling (control signals). FIG. 2 is a diagram illustrating an example of an application scenario of a relay device (NCR device) according to the first embodiment. FIG. 3 is a diagram illustrating an example of an application scenario of a relay device (NCR device) according to the first embodiment. FIG. 4 is a diagram illustrating an example of a control method of a relay device (NCR device) according to the first embodiment. FIG. 4 is a diagram illustrating an example of a configuration of a protocol stack in a mobile communication system having a relay device (NCR device) according to the first embodiment. FIG. 5 is a diagram illustrating an example of a configuration of a relay device (NCR device) according to the first embodiment. FIG. 6 is a diagram illustrating an example of a configuration of a base station (gNB) according to an embodiment. FIG. 7 is a diagram illustrating an example of downlink signaling from a base station (gNB) according to the first embodiment to a control terminal (NCR-MT) according to the first embodiment. FIG. 8 is a diagram illustrating an example of uplink signaling from a control terminal (NCR-MT) according to the first embodiment to a base station (gNB). FIG. 9 is a diagram illustrating an example of an overall operation sequence of a mobile communication system according to the first embodiment. FIG. 10 is a diagram illustrating beam sweeping according to the first embodiment. FIG. 11 is a diagram illustrating carrier aggregation (CA). 10 is a diagram for explaining dual connectivity (DC). FIG. 10 is a diagram for explaining a configuration example when a CA is set in an NCR device (NCR-MT). FIG. 10 is a diagram for explaining a configuration example when a DC is set in an NCR device (NCR-MT). FIG. 10 is a diagram for explaining a first operation example when multiple serving cells by CA according to the first embodiment are used in an NCR device. FIG. 10 is a diagram for explaining a first operation example when multiple serving cells by DC according to the first embodiment are used in an NCR device. FIG. 10 is a diagram for explaining a sCellDeactivationTimer. FIG. 10 is a diagram for explaining a third operation example when multiple serving cells according to the first embodiment are used in an NCR device. FIG. 10 is a diagram for explaining a fourth operation example when multiple serving cells according to the first embodiment are used in an NCR device. FIG. 10 is a diagram for explaining a first operation example related to failure handling in an NCR device according to the first embodiment. FIG. 10 is a diagram for explaining a second operation example related to failure handling in an NCR device according to the first embodiment. FIG. 10 is a diagram for explaining a third operation example related to failure handling in an NCR device according to the first embodiment.FIG. 10 is a diagram for explaining a relay device according to a second embodiment. FIG. 11 is a diagram for explaining a relay device according to the second embodiment. FIG. 12 is a diagram for explaining operations according to other embodiments. FIG. 13 is a diagram for explaining a model of a network controlled repeater. FIG. 14 is a diagram for explaining a protocol stack focusing on the C-plane of an NCR-MT. FIG. 15 is a diagram for explaining a multi-beam NCR. FIG. 16 is a diagram for explaining management model options for a multi-beam repeater. FIG. 17 is a diagram for explaining a CA / DC configuration of an NCR-MT.

[0009] When controlling relay devices such as repeater devices from a network, the control technology for specifically controlling the relay devices has not yet been established, and it is currently difficult to efficiently extend coverage using relay devices.

[0010] Therefore, an object of the present disclosure is to enable appropriate control of a relay device that relays transmission between a base station and a user device.

[0011] 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.

[0012] (1) First Embodiment First, a description will be given of the first embodiment. The relay device according to the first embodiment is a repeater device that can be controlled from a network.

[0013] (1.1) Overview of the 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 conforms to the 5th Generation System (5GS) of the 3rd Generation Partnership Project (3GPP) (registered trademark; the same applies hereinafter) standard. While the following description will be given using 5GS as an example, the mobile communication system may also be at least partially based on the Long Term Evolution (LTE) system. The mobile communication system may also be at least partially based on the sixth generation (6G) system.

[0014] The mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN: Next Generation Radio Access Network) 10, and a 5G core network (5GC: 5G Core Network) 20. Hereinafter, the NG-RAN 10 may be simply referred to as the RAN 10. Furthermore, the 5GC 20 may be simply referred to as the core network (CN) 20.

[0015] The UE 100 is a mobile wireless communication device. The UE 100 may be any device that is used by a user. For example, the UE 100 may be 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 in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0016] The NG-RAN 10 includes a base station (called a "gNB" in a 5G system) 200. The gNBs 200 are connected to each other via an Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with a UE 100 that has established a connection with its own cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, and the like. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource for wireless communication with the UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0017] The gNB200 may be functionally divided into a central unit (CU) and a distributed unit (DU). The CU controls the DU. The CU is a unit including upper layers included in the protocol stack described below, such as an RRC layer, an SDAP layer, and a PDCP layer. The CU is connected to the core network via an NG interface, which is a backhaul interface. The CU is connected to neighboring base stations via an Xn interface, which is an interface between base stations. The DU forms a cell. The DU202 is a unit including lower layers included in the protocol stack described below, such as an RLC layer, a MAC layer, and a PHY layer. The DU is connected to the CU via an F1 interface, which is a fronthaul interface.

[0018] In addition, gNBs can also be connected to the Evolved Packet Core (EPC), which is the core network of LTE. LTE base stations can also be connected to 5GC. LTE base stations and gNBs can also be connected via an inter-base station interface.

[0019] The 5GC20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF controls data forwarding. The AMF and the UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0020] FIG. 2 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0021] The user plane radio interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0022] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of gNB200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from gNB200 on a physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires successfully decoded DCI as DCI addressed to the UE. The DCI transmitted from gNB200 has CRC parity bits scrambled by the RNTI added.

[0023] In addition, the gNB 200 transmits a synchronization signal block (SSB: Synchronization Signal / PBCH block). For example, the SSB is composed of four consecutive OFDM (Orthogonal Frequency Division Multiplex) symbols, and includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH) / master information block (MIB), and a PBCH demodulation reference signal (DMRS). The bandwidth of the SSB is, for example, 240 consecutive subcarriers, that is, a bandwidth of 20 RBs.

[0024] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the gNB 200 via a transport channel. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE 100.

[0025] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 via a logical channel.

[0026] The PDCP layer performs header compression / decompression, encryption / decryption, and the like.

[0027] The SDAP layer maps IP flows, which are units for Quality of Service (QoS) control by the core network, to radio bearers, which are units for QoS control by the Access Stratum (AS). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0028] FIG. 3 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals).

[0029] 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 FIG.

[0030] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according 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 an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in an RRC inactive state.

[0031] The NAS layer, which is located above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the AMF 300A. Note that the UE 100 has an application layer and the like in addition to the radio interface protocol. Also, a layer lower than the NAS layer is called an AS layer.

[0032] (1.2) Example of Application Scenario of Relay Device FIGS. 4 and 5 are diagrams showing an example of application scenario of the NCR device according to the first embodiment.

[0033] Compared to 4G / LTE, 5G / NR enables broadband transmission using higher frequency bands. Radio signals in high frequency bands, such as the millimeter wave band or terahertz wave band, have high line-of-sight properties, which poses a challenge in reducing the coverage of the gNB 200. In FIG. 4, the UE 100 may be located outside the coverage area of ​​the gNB 200, for example, outside an area where radio signals can be received directly from the gNB 200. A shield may exist between the gNB 200 and the UE 100, preventing the UE 100 from communicating with the gNB 200 within line-of-sight.

[0034] As shown in Figure 4, a repeater device (500A), which is a type of relay device that relays radio signals between the gNB 200 and the UE 100 and can be controlled from a network, is introduced into the mobile communication system 1. Hereinafter, such a repeater device will be referred to as an NCR (Network-Controlled Repeater) device. Such a repeater device may also be referred to as a smart repeater device.

[0035] For example, the NCR device 500A amplifies a radio signal (radio wave) received from the gNB 200 and transmits it by directional transmission. Specifically, the NCR device 500A receives a radio signal transmitted by the gNB 200 by beamforming. The NCR device 500A then amplifies the received radio signal without demodulating or modulating it, and transmits the amplified radio signal by directional transmission. Here, the NCR device 500A may transmit a radio signal with a fixed directivity (beam). The NCR device 500A may transmit a radio signal with a variable (adaptive) directional beam. This allows the coverage of the gNB 200 to be efficiently expanded. In the first embodiment, it is mainly assumed that the NCR device 500A is applied to downlink communication from the gNB 200 to the UE 100, but the NCR device 500A can also be applied to uplink communication from the UE 100 to the gNB 200.

[0036] 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 relays radio signals transmitted between the gNB 200 and the UE 100. Specifically, the NCR device 500A has an NCR-Fwd (Forward) 510A, which is a type of repeater that changes the propagation state of the radio signal without demodulating or modulating the radio signal, and an NCR-MT 520A that controls the NCR-Fwd 510A by performing wireless communication with the gNB 200. In this way, the NCR-MT 520A establishes a wireless connection with the gNB 200 and performs wireless communication with the gNB 200, thereby controlling the NCR device 500A in cooperation with the gNB 200. This enables efficient coverage expansion to be achieved using the NCR device 500A. NCR-MT520A controls NCR device 500A in accordance with control from gNB200.

[0037] The NCR-MT 520A may be configured separately from the NCR-Fwd 510A. For example, the NCR-MT 520A may be located near 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 a wall or window of a building. The NCR-MT 520A and the NCR-Fwd 510A may be installed, for example, in a vehicle or the like and be mobile. Also, one NCR-MT 520A may control multiple NCR-Fwds 510A.

[0038] In the example shown in FIG. 5, the NCR device 500A (NCR-Fwd 510A) dynamically or quasi-statically changes the beam to be transmitted or received. For example, the NCR-Fwd 510A forms a beam toward each of the UE 100a and the UE 100b. The NCR-Fwd 510A may also form a beam toward the gNB 200. For example, in the communication resources between the gNB 200 and the UE 100a, the NCR-Fwd 510A transmits a radio signal received from the gNB 200 toward the UE 100a by beamforming, and / or transmits a radio signal received from the UE 100a toward the gNB 200 by beamforming. In the communication resources between the gNB 200 and the UE 100b, the NCR-Fwd 510A transmits a radio signal received from the gNB 200 toward the UE 100b by beamforming, and / or transmits a radio signal received from the UE 100b by beamforming toward the gNB 200. Instead of or in addition to beamforming, the NCR-Fwd 510A may form a null (so-called null steering) toward a UE 100 (not shown) and / or a neighboring gNB 200 (not shown) that is not a communication partner for interference suppression.

[0039] FIG. 6 is a diagram showing an example of a control method for the NCR device 500A according to the first embodiment. As shown in FIG. 6, the NCR-Fwd 510A relays radio signals (also referred to as "UE signals") between the gNB 200 and the UE 100. The UE signals include uplink signals (also referred to as "UE-UL signals") transmitted from the UE 100 to the gNB 200 and downlink signals (also referred to as "UE-DL signals") transmitted from the gNB 200 to the UE 100. The NCR-Fwd 510A relays the UE-UL signals from the UE 100 to the gNB 200 and relays the UE-DL signals from the gNB 200 to the UE 100. The radio link between the NCR-Fwd 510A and the UE 100 is also referred to as an "access link." The wireless link between NCR-Fwd510A and gNB200 is also referred to as a "backhaul link."

[0040] The NCR-MT 520A transmits and receives radio signals (herein referred to as "NCR-MT signals") to and from the gNB 200. The NCR-MT signals include uplink signals (herein referred to as "NCR-MT-UL signals") transmitted from the NCR-MT 520A to the gNB 200, and downlink signals (herein referred to as "NCR-MT-DL signals") transmitted from the gNB 200 to the NCR-MT 520A. The NCR-MT-UL signals include signaling for controlling the NCR device 500A. The radio link between the NCR-MT 520A and the gNB 200 is also referred to as a "control link."

[0041] The gNB200 directs a beam to the NCR-MT520A based on the NCR-MT-UL signal from the NCR-MT520A. Because the NCR device 500A is co-located with the NCR-MT520A, if the backhaul link and the control link have the same frequency, when the gNB200 directs a beam to the NCR-MT520A, the beam will also be directed to the NCR-Fwd510A. The gNB200 uses this beam to transmit an NCR-MT-DL signal and a UE-DL signal. The NCR-MT520A receives the NCR-MT-DL signal. In addition, when the NCR-Fwd 510A and the NCR-MT 520A are at least partially integrated, the functions (e.g., antennas) for transmitting, receiving, or relaying UE signals and / or NCR-MT signals may be integrated in the NCR-Fwd 510A and the NCR-MT 520A. Note that the term "beam" includes a transmitting beam and / or a receiving beam. A beam is a general term for transmission and / or reception controlled to maximize the power of transmitted waves and / or received waves in a specific direction by adjusting / adapting antenna weights, etc.

[0042] 7 is a diagram showing an example of the configuration of a protocol stack in a mobile communication system 1 having an NCR device 500A according to the first embodiment. The NCR-Fwd 510A relays radio signals transmitted and received between the gNB 200 and the UE 100. The NCR-Fwd 510A has an RF (Radio Frequency) function that amplifies and relays received radio signals, and performs directional transmission using beamforming (e.g., analog beamforming).

[0043] The NCR-MT 520A has at least one layer (entity) of PHY, MAC, RRC, and F1-AP (Application Protocol). The F1-AP is a type of fronthaul interface. The NCR-MT 520A exchanges downlink signaling and / or uplink signaling (described below) with the gNB 200 via at least one of PHY, MAC, RRC, and F1-AP. If the NCR-MT 520A is a type or part of a base station, the NCR-MT 520A may exchange with the gNB 200 via an Xn AP (Xn-AP), which is an inter-base station interface.

[0044] 8 is a diagram showing an example of the configuration of an NCR device 500A that is a relay device according to the first embodiment. The NCR device 500A includes an NCR-Fwd 510A, an NCR-MT 520A, and an interface 530.

[0045] The NCR-Fwd 510A includes a radio unit 511A and an NCR control unit 512A. The radio unit 511A includes an antenna unit 511a including multiple antennas (multiple antenna elements), an RF circuit 511b including an amplifier, and a directivity control unit 511c that controls the directivity of the antenna unit 511a. The RF circuit 511b amplifies and relays (transmits) radio signals transmitted and received by the antenna unit 511a. The RF circuit 511b may convert analog radio signals into digital signals and then reconvert them to analog signals after digital signal processing. The directivity control unit 511c may perform analog beamforming using analog signal processing. The directivity control unit 511c may perform digital beamforming using digital signal processing. The directivity control unit 511c may perform hybrid analog and digital beamforming. The NCR control unit 512A controls the radio unit 511A in response to control signals from the NCR-MT 520A. 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-MT 520A.

[0046] The NCR-MT 520A 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 (wireless 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 (transmitted 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-MT 520A. The control unit 523 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in memory to perform various processes. The control unit 523 also executes the functions of at least one of the PHY, MAC, RRC, and F1-AP layers.

[0047] The interface 530 electrically connects the NCR-Fwd 510A and the NCR-MT 520A. The control unit 523 of the NCR-MT 520A controls the NCR-Fwd 510A via the interface 530.

[0048] In the first embodiment, the receiver 521 of the NCR-MT 520A receives signaling (downlink signaling) used to control the NCR device 500A from the gNB 200 via wireless communication. The controller 523 of the NCR-MT 520A controls the NCR device 500A based on the signaling. This enables the gNB 200 to control the NCR-Fwd 510A via the NCR-MT 520A.

[0049] In the first embodiment, the control unit 523 of the NCR-MT 520A may transmit NCR capability information indicating the capabilities of the NCR device 500A to the gNB 200 via wireless communication. The NCR capability information is an example of uplink signaling from the NCR-MT 520A to the gNB 200. This enables the gNB 200 to grasp the capabilities of the NCR device 500A.

[0050] (1.4) Configuration example of base station Figure 9 is a diagram showing a configuration example of the gNB 200 according to the first embodiment. The gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240.

[0051] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna. The receiving unit 220 performs various receptions under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (reception signal) and outputs it to the control unit 230. The transmitting unit 210 and the receiving unit 220 may be capable of beamforming using multiple antennas.

[0052] The control unit 230 performs various controls in the gNB 200. 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 in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0053] The backhaul communication unit 240 is connected to adjacent base stations via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF 300 via a base station-core network interface. The gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally divided), and the two units may be connected via an F1 interface.

[0054] In the first embodiment, the transmitter 210 of the gNB 200 transmits signaling (downlink signaling) used to control the NCR-Fwd 510A to the NCR-MT 520A via wireless communication. This enables the gNB 200 to control the NCR device 500A via the NCR-MT 520A. In the first embodiment, the receiver 220 of the gNB 200 may receive NCR capability information indicating the capabilities of the NCR device 500A from the NCR-MT 520A via wireless communication.

[0055] (1.5) Example of downlink signaling Figure 10 is a diagram showing an example of downlink signaling from gNB200 to NCR-MT520A in the first embodiment.

[0056] The gNB 200 (transmitter 210) transmits downlink signaling to the NCR-MT 520A. 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 interact with gNB200 via Xn's AP (Xn-AP), which is an inter-base station interface.

[0057] For example, the gNB200 (transmitter 210) transmits an NCR control signal specifying the operating state of the NCR device 500A as downlink signaling to the NCR-MT 520A that has established a wireless connection with the gNB200 (step S1A). The NCR control signal specifying the operating state of the NCR device 500A may be a MAC CE, which is signaling of the MAC layer (layer 2), or a DCI, which is signaling of 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-MT 520A. The downlink signaling may be a message of a layer higher than the RRC layer (for example, an NCR application). The downlink signaling may be a message of a layer higher than the RRC layer encapsulated in a message of a layer below the RRC layer and transmitted. In addition, the NCR-MT 520A (transmitter 522) may transmit a response message in response to the downlink signaling from the gNB 200 via the uplink. The response message may be transmitted in response to the NCR device 500A completing the setting specified in the downlink signaling or receiving the setting. The NCR control signal may be referred to as Side Control Information.

[0058] The NCR control signal may include frequency control information that specifies the center frequency of the radio signal (e.g., component carrier) to be relayed by the NCR-Fwd 510A. When the NCR control signal received from the gNB 200 includes frequency control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to relay the radio signal having the center frequency indicated by the frequency control information (step S2A). The NCR control signal may include multiple pieces of frequency control information that specify different center frequencies. By including frequency control information in the NCR control signal, the gNB 200 can specify the center frequency of the radio signal to be relayed by the NCR-Fwd 510A via the NCR-MT 520A.

[0059] The NCR control signal may include mode control information that specifies the operation mode of the NCR-Fwd 510A. The mode control information may be associated with frequency control information (center frequency). The operation mode may be any of a mode in which the NCR-Fwd 510A performs omnidirectional transmission and / or reception, a mode in which the NCR-Fwd 510A performs fixed-directivity transmission and / or reception, a mode in which the NCR-Fwd 510A performs transmission and / or reception using a variable directional beam, and a mode in which the NCR-Fwd 510A performs MIMO (Multiple Input Multiple Output) relay transmission. The operation mode may be any of a beamforming mode (i.e., a mode that emphasizes improving the desired wave) and a null steering mode (i.e., a mode that emphasizes suppressing interference waves). When the NCR control signal received from the gNB 200 includes mode control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to operate in the operating mode indicated by the mode control information (step S2A). By including the mode control information in the NCR control signal, the gNB 200 can specify the operating mode of the NCR-Fwd 510A via the NCR-MT 520A.

[0060] Here, the mode in which the NCR device 500A performs omnidirectional transmission and / or reception is a mode in which the NCR-Fwd 510A performs omnidirectional relaying, and may be referred to as omni-mode. The mode in which the NCR-Fwd 510A performs fixed directional transmission and / or reception may be a directional mode realized by a single directional antenna. This mode may be a beamforming mode realized by applying fixed phase / amplitude control (antenna weight control) to multiple antennas. Any of these modes may be specified (set) by the gNB 200 to the NCR-MT 520A. The mode in which the NCR-Fwd 510A performs transmission and / or reception using a variable directional beam may be a mode in which analog beamforming is performed. This mode may be a mode in which digital beamforming is performed. This mode may be a mode in which hybrid beamforming is performed. This mode may be a mode in which an adaptive beam specific to the UE 100 is formed. Any of these modes may be specified (set) from the gNB 200 to the NCR-MT 520A. Note that in an operation mode in which beamforming is performed, beam control information, described below, may be provided from the gNB 200 to the NCR-MT 520A. The mode in which the NCR device 500A performs MIMO relay transmission may be a mode in which SU (Single-User) spatial multiplexing is performed. This mode may also be a mode in which MU (Multi-User) spatial multiplexing is performed. This mode may also be a mode in which transmit diversity is performed. Any of these modes may be specified (set) from the gNB 200 to the NCR-MT 520A. The operation modes may include a mode in which relay transmission by the NCR-Fwd 510A is turned on (activated) and a mode in which relay transmission by the NCR-Fwd 510A is turned off (deactivated). Any of these modes may be specified (set) by an NCR control signal from gNB200 to NCR-MT520A.

[0061] The NCR control signal may include beam control information that specifies the transmission direction, transmission weight, or beam pattern when the NCR-Fwd 510A 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 beam formation angle information. When the NCR control signal received from the gNB 200 includes beam control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to form the transmission directivity (beam) indicated by the beam control information (step S2A). By including beam control information in the NCR control signal, the gNB 200 can control the transmission directivity of the NCR device 500A via the NCR-MT 520A.

[0062] The NCR control signal may include output control information that specifies the degree to which the NCR-Fwd 510A amplifies the radio signal (amplification gain) or transmission power. The output control information may be information indicating a difference value (i.e., a relative value) between the current amplification gain or transmission power and the target amplification gain or transmission power. When the NCR control signal received from the gNB 200 includes output control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to change the amplification gain or transmission power 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 that specifies any one of the amplifier gain, beamforming gain, and antenna gain of the NCR-Fwd 510A. The output control information may be information that specifies the transmission power of the NCR-Fwd 510A.

[0063] When one NCR-MT 520A controls multiple NCR-Fwds 510A, the gNB 200 (transmitter 210) may transmit an NCR control signal to the NCR-MT 520A for each NCR-Fwd 510A. In this case, the NCR control signal may include an identifier (NCR identifier) ​​of the corresponding NCR-Fwd 510A. The NCR-MT 520A (controller 523) that controls multiple NCR-Fwds 510A determines the NCR-Fwd 510A to which the NCR control signal is applied based on the NCR identifier included in the NCR control signal received from the gNB 200. Note that the NCR identifier may be transmitted from the NCR-MT 520A to the gNB 200 together with the NCR control signal, even when the NCR-MT 520A controls only one NCR-Fwd 510A.

[0064] In this way, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A based on the NCR control signal from the gNB 200. This enables the gNB 200 to control the NCR-Fwd 510A via the NCR-MT 520A.

[0065] (1.6) Example of uplink signaling Figure 11 is a diagram showing an example of uplink signaling from NCR-MT520A to gNB200 in the first embodiment.

[0066] The NCR-MT 520A (transmitter 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 be a message of a layer higher than the RRC layer encapsulated in a message of a layer lower than the RRC layer and transmitted. That is, the uplink signaling stores an upper layer message in a lower layer container. Note that the gNB 200 (transmitter 210) transmits a response message to the uplink signaling from the NCR-MT 520A on the downlink, and the NCR-MT 520A (receiver 521) may receive the response message.

[0067] For example, the NCR-MT 520A (transmitter 522) that has established a wireless 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-MT 520A (transmitter 522) may include the NCR capability information in a UE Capability message or a UE Assistant Information message, which are types of RRC messages, and transmit the message to the gNB 200. The NCR-MT 520A (transmitter 522) may transmit the NCR capability information (NCR capability information and / or operation status information) to the gNB 200 in response to a request or inquiry from the gNB 200.

[0068] The NCR capability information may include supported frequency information indicating the frequencies supported by the NCR-Fwd 510A. The supported frequency information may be a numerical value or index indicating the center frequency of the frequencies supported by the NCR-Fwd 510A. The supported frequency information may be a numerical value or index indicating the range of frequencies supported by the NCR-Fwd 510A. When the NCR capability information received from the NCR-MT 520A includes supported frequency information, the gNB 200 (control unit 230) can determine the frequencies supported by the NCR-Fwd 510A based on the supported frequency information. Then, the gNB 200 (control unit 230) may set the center frequency of the radio signal targeted by the NCR device 500A within the range of frequencies supported by the NCR-Fwd 510A.

[0069] The NCR capability information may include mode capability information regarding operation modes that the NCR-Fwd 510A can support or switching between operation modes. As described above, the operation mode may be at least one of a mode in which the NCR-Fwd 510A performs omnidirectional transmission and / or reception, a mode in which the NCR-Fwd 510A performs fixed-directivity transmission and / or reception, a mode in which the NCR-Fwd 510A performs transmission and / or reception using a variable directional beam, and a mode in which the NCR-Fwd 510A 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 be information indicating which of these operation modes the NCR-Fwd 510A can support. The mode capability information may be information indicating which of these operation modes mode switching is possible between. When the NCR capability information received from the NCR-MT 520A includes mode capability information, the gNB 200 (control unit 230) can determine the operation modes and mode switching supported by the NCR-Fwd 510A based on the mode capability information. The gNB 200 (control unit 230) may then set the operation mode of the NCR-Fwd 510A within the range of the determined operation modes and mode switching.

[0070] The NCR capability information may include beam capability information indicating the beam variable range, beam variable resolution, or number of variable patterns when the NCR-Fwd 510A transmits and / or receives using a variable directional beam. The beam capability information may be, for example, information indicating the variable range of the beam angle based on the horizontal or vertical direction (e.g., controllable from 30° to 90°). The beam capability information may be information indicating an absolute angle. The beam capability information may be expressed by the direction and / or elevation angle of the beam. 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 beam patterns in the NCR-Fwd 510A (e.g., beam patterns 1 to 10, a total of 10 patterns). When the NCR capability information received from the NCR-MT 520A includes beam capability information, the gNB 200 (control unit 230) can determine the beam angle change or beam pattern that the NCR-Fwd 510A can support based on the beam capability information. The gNB 200 (control unit 230) may then set the beam of the NCR-Fwd 510A within the range of the determined beam angle change or beam pattern. This beam capability information may be null capability information. In the case of null capability information, this beam capability information indicates the null control capability when null steering is performed.

[0071] 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 UE 100 receives the NCR control signal or the timing when the UE 100 transmits the setting completion for the NCR control signal to the gNB 200 until the control (change of operating mode and / or change of beam) according to the NCR control signal is completed. When the NCR capability information received from the NCR-MT 520A includes control delay information, the gNB 200 (control unit 230) can grasp the control delay time in the NCR-Fwd 510A based on the control delay information.

[0072] The NCR capability information may include amplification characteristic information regarding the amplification characteristic or output power characteristic of the radio signal in the NCR-Fwd 510A. The amplification characteristic information may be information indicating the amplifier gain (dB), beamforming gain (dB), or antenna gain (dBi) of the NCR-Fwd 510A. The amplification characteristic information may be information indicating the amplification variable range (e.g., 0 dB to 60 dB) of the NCR-Fwd 510A. The amplification characteristic information may be information indicating the number of steps (e.g., 10 steps) of the gain that can be changed by the NCR-Fwd 510A, or the gain per variable step (e.g., 10 dB / step). The amplification characteristic information may be information indicating the variable range (e.g., 0 dBm to 30 dBm) of the output power of the NCR-Fwd 510A. The amplification characteristic information may be information indicating the number of steps (for example, 10 steps) of the output power that can be changed by the NCR-Fwd 510A, or the output power per variable step (for example, 10 dBm / step or 10 dB / step).

[0073] The NCR capability information may include location information indicating the installation location of the NCR device 500A. The location information may include one or more of latitude, longitude, and altitude. The location information may include information indicating the distance and / or installation angle of the NCR device 500A based on the gNB 200. The installation angle may be a relative angle with respect to the gNB 200, or may be a relative angle based on, for example, north, vertical, or horizontal. The installation location may be location information of the location where the antenna unit 511a of the NCR-Fwd 510A is installed.

[0074] The NCR capability information may include antenna information indicating the number of antennas possessed by the NCR-Fwd 510A. The antenna information may be information indicating the number of antenna ports possessed by the NCR-Fwd 510A. The antenna information may be information indicating the degrees of freedom of directivity control (beam or null formation). The degrees of freedom indicate how many beams can be formed (controlled) and are usually "(number of antennas) - 1". For example, in the case of two antennas, the degrees of freedom are 1. In the case of two antennas, a beam pattern resembling a figure eight is formed, but directivity control is possible in only one direction, so the degrees of freedom are 1.

[0075] When the NCR-MT 520A controls multiple NCR-Fwds 510A, the NCR-MT 520A (transmitter 522) may transmit NCR capability information to the gNB 200 for each NCR-Fwd 510A. In this case, the NCR capability information may include the number of NCR-Fwds 510A and / or the identifier (NCR identifier) ​​of the corresponding NCR-Fwd 510A. Furthermore, when the NCR-MT 520A controls multiple NCR-Fwds 510A, the NCR-MT 520A (transmitter 522) may transmit information indicating at least one of the identifiers of the multiple NCR-Fwds 510A and the number of the multiple NCR-Fwds 510A. In addition, the NCR identifier may be transmitted from NCR-MT 520A to gNB 200 together with NCR capability information, even if NCR-MT 520A controls only one NCR-Fwd 510A.

[0076] (1.7) Example of Overall Operation Sequence Fig. 12 is a diagram showing an example of an overall operation sequence of the mobile communication system 1 according to the first embodiment. In the sequence diagrams referred to in the following embodiments, non-essential steps are indicated by dashed lines. Note that, as will be described in detail later, "NCR" in Fig. 12 may be read as "RIS".

[0077] In step S11, gNB200 (transmitter 210) broadcasts NCR support information indicating that gNB200 supports NCR-MT520A. For example, gNB200 (transmitter 210) broadcasts a system information block (SIB) including NCR support information. The NCR support information may be information indicating that NCR-MT520A is accessible. Alternatively, gNB200 (transmitter 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.

[0078] At this stage, the NCR-MT 520A may be in an RRC idle state or an RRC inactive state. The NCR-MT 520A (control unit 523), which has not established a wireless connection with the gNB 200, may determine that access to the gNB 200 is permitted in response to receiving NCR support information from the gNB 200, and may perform an access operation to establish a wireless connection with the gNB 200. The NCR-MT 520A (control unit 523) may perform cell reselection by regarding the gNB 200 (cell) to which access is permitted as having the highest priority.

[0079] On the other hand, if the NCR-MT520A (control unit 523) that has not established a wireless connection with the gNB200 does not broadcast NCR support information (or broadcasts NCR non-support information), it may determine that it is unable to access (establish a connection with) the gNB200. This allows the NCR-MT520A to establish a wireless connection only with gNB200 that can handle the NCR-MT520A.

[0080] In addition, when the gNB200 is congested, the gNB200 may broadcast access restriction information that restricts access from the UE100. However, unlike a normal UE100, the NCR-MT520A can also be considered a network-side entity. Therefore, the NCR-MT520A may ignore the access restriction information from the gNB200. For example, when the NCR-MT520A (control unit 523) receives NCR support information from the gNB200, it may perform an operation to establish a wireless connection with the gNB200 even if the gNB200 is broadcasting access restriction information. For example, the NCR-MT520A (control unit 523) may not execute (or may ignore) UAC (Unified Access Control). Alternatively, a special value indicating that the access is an NCR-MT access may be used for either or both of the AC / AI (Access Category / Access Identity) used in the UAC.

[0081] In step S12, the NCR-MT 520A (control unit 523) initiates a random access procedure for the gNB 200. In the random access procedure, the NCR-MT 520A (transmitting unit 522) transmits a random access preamble (Msg1) and an RRC message (Msg3) to the gNB 200. Also, in the random access procedure, the NCR-MT 520A (receiving unit 521) receives a random access response (Msg2) and an RRC message (Msg4) from the gNB 200.

[0082] In step S13, when establishing a wireless connection with the gNB 200, the NCR-MT 520A (transmitter 522) may transmit NCR-MT information indicating that its own UE is an NCR-MT to the gNB 200. For example, during a random access procedure with the gNB 200, the NCR-MT 520A (transmitter 522) includes the NCR-MT information in a random access procedure message (e.g., Msg1, Msg3, Msg5) and transmits it to the gNB 200. Based on the NCR-MT information received from the NCR-MT 520A, the gNB 200 (controller 230) recognizes that the accessed UE 100 is the NCR-MT 520A, and can, for example, exclude the NCR-MT 520A from the access restriction target (i.e., accept access). Once the random access procedure is completed, the NCR-MT 520A transitions from the RRC idle state or the RRC inactive state to the RRC connected state.

[0083] In step S14, gNB200 (transmitter 522) transmits a capability inquiry message to NCR-MT520A to inquire about the capabilities of NCR-MT520A. NCR-MT520A (receiver 521) receives the capability inquiry message.

[0084] In step S15, the NCR-MT 520A (transmitter 522) transmits a capability information message including NCR capability information to the gNB 200. The capability information message may be an RRC message, for example, a UE Capability message. The gNB 200 (receiver 220) receives the capability information message. The gNB 200 (controller 230) determines the capabilities of the NCR device 500A based on the received capability information message.

[0085] In step S16, the gNB200 (transmitter 522) transmits a configuration message including various settings related to the NCR device 500A to the NCR-MT 520A. The NCR-MT 520A (receiver 521) receives the configuration message. The configuration message is a type of the downlink signaling described above. The configuration message may be an RRC message, for example, an RRC Reconfiguration message.

[0086] In step S17, the gNB 200 (transmitter 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 (e.g., L1 / L2 signaling). The NCR-MT 520A (receiver 521) receives the control instruction. The NCR-MT 520A (controller 523) controls the NCR-Fwd 510A in accordance with the control instruction.

[0087] In step S18, the NCR-MT 520A controls the NCR device 500A according to the above settings (and control instructions). Note that the NCR-MT 520A may autonomously control the NCR device 500A without relying on control instructions from the gNB 200. For example, the NCR-MT 520A may autonomously control the NCR device 500A based on the location of the UE 100 and / or information received by the NCR-MT 520A from the UE 100.

[0088] (1.8) Beam Sweeping FIG. 13 is a diagram for explaining beam sweeping according to the embodiment.

[0089] The gNB200 performs beam sweeping, which sequentially switches beams in different directions while transmitting. At this time, the gNB200 transmits a different SSB for each beam. The SSBs are periodically transmitted from the gNB200 to the cell as SSB bursts consisting of multiple SSBs. Each of the multiple SSBs in an SSB burst is assigned an SSB index, which is an identifier. The SSBs are beamformed and transmitted in different directions. The NCR device 500A (NCR-MT520A) reports to the gNB200 during the random access channel (RACH) procedure which direction the beam had good reception quality. Specifically, the NCR device 500A (NCR-MT520A) transmits a random access preamble to the gNB200 in a random access channel (RACH) occasion associated with the SSB index for which the beam had good reception quality. As a result, gNB200 can determine the optimal beam for NCR device 500A (NCR-MT520A).

[0090] Note that such an SSB may be transmitted in an initial BWP (initial DL BWP). When the NCR device 500A (NCR-MT 520A) is in an RRC connected state, a dedicated BWP may be configured and activated in the NCR device 500A (NCR-MT 520A). In the dedicated BWP, a channel state information reference signal (CSI-RS) may be used as a reference signal instead of an SSB. Hereinafter, an example in which beam information identifying a beam is an SSB index will be mainly described, assuming that there is a one-to-one relationship between a beam and an SSB (specifically, an SSB index). However, a beam may be associated with a CSI-RS. The beam information identifying a beam may be a CSI-RS index.

[0091] (1.9) Carrier Aggregation and Dual Connectivity As described in the following embodiments, in the embodiment, the gNB 200 can set multiple serving cells to the NCR device 500A (NCR-MT 520A) by carrier aggregation (CA) or dual connectivity (DC). Before describing such operations, general CA and DC will be described.

[0092] 14 is a diagram for explaining CA. In CA, a plurality of component carriers (CCs) corresponding to a plurality of serving cells are aggregated, and the UE 100 can simultaneously receive or transmit on the plurality of CCs. The plurality of CCs may be contiguous in the frequency direction. The plurality of CCs may also be discontinuous.

[0093] When CA is configured, the UE 100 has only one RRC connection with the network (e.g., gNB 200). During RRC connection establishment / re-establishment / handover, one serving cell provides NAS mobility information, and during RRC connection re-establishment / handover, one serving cell provides security input. This one serving cell is called a primary cell (PCell). A set of serving cells can be formed by configuring a PCell and a secondary cell (SCell) for the UE 100. Therefore, the set of serving cells configured for the UE 100 always consists of one PCell and one or more SCells. Reconfiguration, addition, and deletion of SCells can be performed by RRC. Note that the primary cell is an MCG cell operating on a primary frequency where the UE 100 performs an initial connection establishment procedure or initiates a connection re-establishment procedure. When UE 100 receives an RRCSetup message from a cell in the initial connection establishment procedure, UE 100 regards the cell as a primary cell.

[0094] FIG. 15 is a diagram for explaining a DC. In the DC, the UE 100 communicates with a master cell group (MCG) 201M managed by a master node (MN) 200M and a secondary cell group (SCG) 201S managed by a secondary node (SN) 200S. The MN 200M and the SN 200S are connected to each other via a network interface (specifically, an inter-base station interface). The network interface may be an Xn interface or an X2 interface. The MN 200M may be referred to as a master base station, and the SN 200S may be referred to as a secondary base station. In the following description of the embodiment, an example will be described in which the MN 200M and the SN 200S are both gNBs 200, but at least one of the MN 200M and the SN 200S may be an LTE base station (eNB).

[0095] For example, DC is started when MN200M sends a predetermined message (for example, an SN Addition Request message) to SN200S, and MN200M sends an RRC reconfiguration message to UE100. In DC, UE100 in the RRC connected state is assigned radio resources from the respective schedulers of MN200M and SN200S, and performs radio communication using the radio resources of MN200M and the radio resources of SN200S.

[0096] The MN 200M may have a control plane connection with the core network. The MN 200M provides the primary radio resources for the UE 100. The MN 200M manages the MCG 201M. The MCG 201M is a group of serving cells associated with the MN 200M. The MCG 201M has a primary cell (PCell) and optionally has one or more secondary cells (SCells). On the other hand, the SN 200S may not have a control plane connection with the core network. The SN 200S provides additional radio resources to the UE 100. The SN 200S manages the SCG 201S. The SCG 201S has a primary / secondary cell (PSCell) and optionally has one or more SCells. The PCell of the MCG 201M and the PSCell of the SCG 201S are sometimes referred to as special cells (SpCells).

[0097] (1.10) Operation of a Relay Device Using Multiple Serving Cells The operation of a relay device (NCR device 500A) using multiple serving cells will be described. Fig. 16 is a diagram showing a configuration example when CA is set in the NCR device 500A (NCR-MT 520A).

[0098] In the embodiment, the control link (i.e., the radio link between the NCR-MT 520A and the gNB 200) and the backhaul link (i.e., the radio link between the NCR-Fwd 510A and the gNB 200) have the same frequency. This frequency is also referred to as a "predetermined frequency." This allows the channel conditions of the control link and the backhaul link to be aligned, thereby simplifying the control of the NCR-Fwd 510A. For example, based on channel state information (CSI) feedback transmitted from the NCR-Fwd 510A to the gNB 200, the gNB 200 can grasp the channel conditions of the backhaul link and perform appropriate beamforming and link adaptation (such as determining the MCS) for the backhaul link.

[0099] Therefore, when multiple serving cells are set in the NCR device 500A (NCR-MT 520A), the gNB 200 sets a cell C2 corresponding to the frequency of the radio signal (from another perspective, the component carrier) relayed by the NCR-Fwd 510A in the NCR device 500A (NCR-MT 520A). This frequency is also referred to as the "operating frequency of the NCR-Fwd 510A." The serving cell C2 is used for the control link and the backhaul link. The NCR-MT 520A communicates with the gNB 200 via the control link in Layer 1 and / or Layer 2 (L1 / L2).

[0100] Here, the frequency of the serving cell C2 may be a frequency in the millimeter wave band (also referred to as "FR (Frequency Range) 2"). It is difficult to achieve stable wireless communication in such a high frequency band. Therefore, in the embodiment, by setting a serving cell C1 having a different frequency from that of the serving cell C2 in the NCR device 500A (NCR-MT 520A), it is possible to establish an RRC connection belonging to Layer 3 (L3) at a different frequency. This allows the control link and the RRC connection to be separated. The serving cell C1 may have a frequency lower than that of the serving cell C2, for example, a frequency in the Sub-6 band (also referred to as "FR1"). In the embodiment, the serving cell C1 is a primary cell, and the serving cell C2 is a secondary cell. This makes it possible to stabilize the RRC connection of the NCR-MT 520A while simplifying the control of the NCR-Fwd 510A.

[0101] FIG. 17 is a diagram showing an example of the configuration when DC is set in the NCR device 500A (NCR-MT520A).

[0102] In the case of DC, a serving cell C1 is provided in the MN (gNB) 200M, and a serving cell C2 is provided in the SN (gNB) 200S. For example, the serving cell C1 is a primary cell belonging to the MCG 201M of the MN 200M. The serving cell C2 is a secondary cell belonging to the SCG 201S of the SN 200S.

[0103] Thus, in the embodiment, the NCR-Fwd 510A relays radio signals of a predetermined frequency transmitted between the gNB 200 and the UE 100. The NCR-MT 520A controls the NCR-Fwd 510A by performing wireless communication with the gNB 200. The gNB 200 configures the NCR-MT 520A with multiple serving cells, including a cell C1 corresponding to a predetermined frequency. This allows the channel conditions to be aligned in the control link and the backhaul link, simplifying the control of the NCR-Fwd 510A. In the embodiment, the cell C2 corresponding to the predetermined frequency is a secondary cell. The secondary cell may be a primary secondary cell (PSCell) in the DC.

[0104] The secondary cell may be inactive (i.e., not used for communication) at the time of setting. The NCR-MT 520A in which the secondary cell is set may receive an activation instruction to activate the secondary cell from the gNB 200. In response to receiving the activation instruction, the NCR-MT 520A may activate the operation of the NCR-Fwd 510A, i.e., make it available for relaying. This allows the operation of the NCR-Fwd 510A to be inactive while the secondary cell is inactive, thereby suppressing power consumption by the NCR-Fwd 510A and the occurrence of unexpected interference.

[0105] The NCR-MT 520A may receive a deactivation instruction to deactivate the secondary cell from the gNB 200. In response to receiving the activation instruction, the NCR-MT 520A may deactivate the operation of the NCR-Fwd 510A.

[0106] In the case of DC, the MN 200M may transmit information regarding the NCR device 500A to the SN 200S on the network interface (inter-base station interface). For example, the MN 200M may transmit information indicating that an SCG for the NCR device 500A is being added to the SN 200S during SN Addition. The MN 200M may transmit to the SN 200S a cell ID (i.e., the cell identifier of cell C2) to be associated with the NCR-Fwd 510A. This makes it easier to realize the operation shown in FIG. 17.

[0107] In the embodiment, a primary cell is used for the RRC connection between the gNB200 and the NCR-MT520A. A secondary cell is used for the control link between the gNB200 and the NCR-MT520A. This makes it possible to use different frequencies for the control link and the RRC connection (i.e., to separate the control link and the RRC connection).

[0108] The NCR-MT 520A may receive an RRC message including configuration information for configuring a secondary cell from the gNB 200. The configuration information may include information for associating the secondary cell with the NCR-Fwd 510A. This makes it possible to explicitly specify the NCR-Fwd 510A to be associated with the secondary cell, even in cases where the NCR device 500A has multiple NCR-Fwds 510A.

[0109] The NCR-MT 520A may receive a control signal for controlling the NCR-Fwd 510A (i.e., the above-mentioned NCR control signal) from the gNB 200 via the control link. The NCR control signal may include identification information for identifying the NCR-Fwd 510A. This makes it possible to explicitly specify the NCR-Fwd 510A to be controlled, even if the NCR device 500A has multiple NCR-Fwds 510A.

[0110] (1.10.1) First Operation Example Using Multiple Serving Cells in a Relay Device FIG. 18 is a diagram showing a first operation example using multiple serving cells by CA in an NCR device 500A.

[0111] In step S101, the NCR-MT 520A establishes an RRC connection with the gNB 200 and enters an RRC connected state. The NCR-MT 520A is assigned the primary cell (serving cell C1) of the gNB 200. The NCR-MT 520A may transmit the above-mentioned NCR capability information to the gNB 200. The NCR capability information may include information indicating that the secondary cell supports control of the NCR-Fwd 510A.

[0112] In step S102, the gNB 200 performs CA configuration for the NCR-MT 520A. For example, the gNB 200 transmits an RRC message (e.g., an RRC Reconfiguration message) including CA configuration information to the NCR-MT 520A on the primary cell (serving cell C1). The NCR-MT 520A receives the CA configuration information. The CA configuration information includes information that associates the secondary cell (serving cell C2) configured for the NCR-MT 520A with the NCR-Fwd 510A. For example, the CA configuration information may include at least one list of sets of an identifier of the secondary cell (serving cell C2) and an identifier of the NCR-Fwd 510A. The CA setting information may include information indicating which secondary cell (serving cell C2) will control NCR-MT520A (i.e., which control link will be established).

[0113] In step S103, the gNB200 transmits an activation instruction for the secondary cell to the NCR-MT520A. For example, the gNB200 transmits a MAC CE including the activation instruction to the NCR-MT520A on the primary cell (serving cell C1). The NCR-MT520A receives the activation instruction. The activation instruction may include an identifier of the secondary cell to be activated.

[0114] In step S104, in response to receiving the activation instruction, the NCR-MT 520A activates the secondary cell (serving cell C2) set in step S102. The NCR-MT 520A may also activate the NCR-Fwd 510A. Upon activating the secondary cell (serving cell C2), the NCR-MT 520A starts beam selection and CSI feedback in the secondary cell (serving cell C2). Note that the secondary cell activation instruction and the NCR-Fwd 510A activation instruction may be separate signaling. In this case, the NCR-MT 520A may activate the secondary cell when it receives the secondary cell activation instruction, and may activate the NCR-Fwd 510A when it receives the NCR-Fwd 510A activation instruction.

[0115] In step S105, the gNB 200 transmits an NCR control signal (L1 / L2 signal) to the NCR-MT 520A on the control link in the secondary cell (serving cell C2). The NCR-MT 520A receives the NCR control signal (L1 / L2 signal). The NCR control signal may include an identifier of the NCR-Fwd 510A.

[0116] In step S106, the NCR-MT 520A controls the NCR-Fwd 510A in accordance with the NCR control signal received in step S105.

[0117] Then, in step S107, the gNB200 transmits a deactivation instruction for the secondary cell to the NCR-MT 520A. For example, the gNB200 transmits a MAC CE including the deactivation instruction to the NCR-MT 520A on the primary cell (serving cell C1) or the secondary cell (serving cell C2). The NCR-MT 520A receives the deactivation instruction. The deactivation instruction may include an identifier of the secondary cell to be deactivated.

[0118] In step S108, in response to receiving the deactivation instruction, the NCR-MT 520A deactivates the secondary cell (serving cell C2) activated in step S104. The NCR-MT 520A may also deactivate the NCR-Fwd 510A. Upon deactivating the secondary cell (serving cell C2), the NCR-MT 520A terminates beam selection and CSI feedback in the secondary cell (serving cell C2). The secondary cell deactivation instruction and the NCR-Fwd 510A deactivation instruction may be separate signals. In this case, the NCR-MT 520A may deactivate the secondary cell when it receives a secondary cell deactivation instruction, and may deactivate the NCR-Fwd 510A when it receives a deactivation instruction for the NCR-Fwd 510A.

[0119] 19 is a diagram showing a first operation example in which multiple serving cells by DC are used in the NCR device 500A. Duplicate explanations of operations similar to those in the case of CA described above will be omitted.

[0120] In step S201, NCR-MT 520A establishes an RRC connection with MN 200M (gNB 200) and enters an RRC connected state. MN 200M's primary cell (serving cell C1) is assigned to NCR-MT 520A. Note that NCR-MT 520A may transmit the above-mentioned NCR capability information to gNB 200. The NCR capability information may include information indicating that control of NCR-Fwd 510A by a secondary cell is supported. Prior to step S202, SN 200S may transmit an SN Addition Required message to MN 200M to request that SN addition is required. The message may include information indicating that an NCR addition is being requested. Upon receiving the message, MN 200M may execute step S202.

[0121] In step S202, the MN 200M transmits an SN Addition Request message to the SN 200S over the inter-base station interface. The SN 200S receives the SN Addition Request message. The SN Addition Request message may include information indicating that an SCG is being added for control of the NCR device 500A. The SN Addition Request message may include information associating the NCR-Fwd 510A with a secondary cell. For example, the SN Addition Request message may include a list including at least one set of an identifier of the NCR-Fwd 510A, an identifier of the NCR device 500A, and / or an identifier of the NCR-MT 520A and a cell ID. The SN Addition Request message may include a list including at least one set of an identifier of the NCR-Fwd 510A, an identifier of the NCR device 500A, and / or an identifier of the NCR-MT 520A and an identifier of a frequency.

[0122] In step S203, the SN 200S transmits an SN Addition Request Acknowledge message including an RRC Reconfiguration (RRC container) to be sent to the NCR-MT 520A to the MN 200M on the base station interface. The MN 200M receives the SN Addition Request Acknowledge message. The RRC Reconfiguration (RRC container) includes DC setting information. The DC setting information includes information that associates the secondary cell (serving cell C2) set in the NCR-MT 520A with the NCR-Fwd 510A. For example, the DC setting information may include at least one list of a set of an identifier of a secondary cell (serving cell C2) and an identifier of the NCR-Fwd 510A. The DC setting information may include information indicating which secondary cell (serving cell C2) controls the NCR-MT 520A (i.e., whether to establish a control link). The DC setting information may include information indicating the operating frequency of the NCR-Fwd 510A.

[0123] In step S204, MN200M transmits the RRC Reconfiguration (DC setting information) included in the SN Addition Request Acknowledge message received in step S203 to NCR-MT520A.

[0124] The operations of steps S205 to S210 are the same as those of steps S103 to S108 in FIG. 18 . However, the secondary cell activation / deactivation instruction may be transmitted from the SN 200S to the NCR-MT 520A. Prior to step S205 or S209, the SN 200S may transmit a message requesting NCR activation or deactivation to the MN 200M. Upon receiving the message, the MN 200M may execute step S205 or S209. Furthermore, the SN 200S may request the MN 200M to remove the NCR setting. Upon receiving the request, the MN 200M may transmit an SN Removal Request message to the SN 200S. The message may be a message for removing the setting of the NCR device 500A. For example, the message may be a message to remove the setting of the NCR-Fwd 510A.

[0125] (1.10.2) Second Operation Example Using Multiple Serving Cells in a Relay Device This operation example is an operation example related to a secondary cell deactivation timer (also referred to as "sCellDeactivationTimer"). The sCellDeactivationTimer is a timer that the gNB 200 associates with a secondary cell and sets in the UE 100. The sCellDeactivationTimer is a timer for deactivating a secondary cell in response to a predetermined period of time during which no data communication has occurred in the secondary cell, and is used to measure the predetermined period of time. This makes it possible to voluntarily deactivate an unused secondary cell.

[0126] Fig. 20 is a diagram for explaining sCellDeactivationTimer. "A" to "C" in Fig. 20 indicate the contents of the 3GPP technical specification "TS38.321" (i.e., MAC protocol specification), and "D" in Fig. 20 indicates the contents of the 3GPP technical specification "TS38.331" (i.e., RRC protocol specification).

[0127] As shown in "A" in Fig. 20, the UE 100 in which the sCellDeactivationTimer is set deactivates the secondary cell (SCell) associated with the sCellDeactivationTimer in response to expiration of the sCellDeactivationTimer. Note that the sCellDeactivationTimer can be set individually for each secondary cell (SCell).

[0128] As shown in "B" in FIG. 20, the UE 100 in which the sCellDeactivationTimer is set starts or restarts the sCellDeactivationTimer in response to activation of the secondary cell (SCell) associated with the sCellDeactivationTimer.

[0129] As shown in "C" in Figure 20, the UE 100 in which the sCellDeactivationTimer is set receives DCI for resource allocation, specifically, a DL assignment or a UL grant, on the PDCCH of the secondary cell (SCell) associated with the sCellDeactivationTimer or the PDCCH of the serving cell that schedules the secondary cell (SCell). In response to receiving the sCellDeactivationTimer. In addition, the UE 100 restarts the sCellDeactivationTimer in response to receiving or transmitting data (MAC PDU) in downlink or uplink resources previously assigned by the configured grant.

[0130] As shown in "D" in FIG. 20, when the sCellDeactivationTimer is not set in the secondary cell, the UE 100 applies infinity as the timer value of the sCellDeactivationTimer of the secondary cell.

[0131] Assuming the operation of FIG. 20 , when the NCR-MT 520A is controlled by the secondary cell (serving cell C2), that is, when a control link of the NCR-MT 520A is provided to the secondary cell (serving cell C2), the following problem occurs. Specifically, if the sCellDeactivationTimer is set in the secondary cell (serving cell C2), there is a concern that the secondary cell (serving cell C2) will be deactivated upon expiration of the sCellDeactivationTimer. For example, if the NCR control signal received on the control link is a MAC CE, or if the NCR control signal received on the control link is a non-scheduling DCI, it is considered that the NCR-MT 520A will not restart the sCellDeactivationTimer in response to receiving the NCR control signal. As a result, the secondary cell (serving cell C2) may be deactivated, which may cause a problem in that control of the NCR device 500A (NCR-MT 520A) may be interrupted.

[0132] Therefore, the gNB 200 that sets the secondary cell (serving cell C2) associated with the NCR-Fwd 510A to the NCR-MT 520A does not set the sCellDeactivationTimer on the secondary cell. That is, the gNB 200 avoids setting the SCell deactivation timer on the secondary cell that forms the control link of the NCR-Fwd 510A (setting the sCellDeactivationTimer on the secondary cell is prohibited). As a result, the NCR-MT 520A applies an infinity value as the timer value of the sCellDeactivationTimer, so that the secondary cell (serving cell C2) can be prevented from being deactivated by the sCellDeactivationTimer.

[0133] Alternatively, when the sCellDeactivationTimer is set for a secondary cell that forms a control link with the NCR-Fwd 510A, the NCR-MT 520A may ignore the timer value of the sCellDeactivationTimer (i.e., the set sCellDeactivationTimer) and apply an infinity value as the timer value of the sCellDeactivationTimer. This prevents the secondary cell (serving cell C2) from being deactivated by the sCellDeactivationTimer.

[0134] (1.10.3) Third Operation Example Using Multiple Serving Cells in a Relay Device This operation example is a modified example of the second operation example described above. In this operation example, the NCR-MT 520A restarts the sCellDeactivationTimer in response to receiving an NCR control signal for controlling the NCR-Fwd 510A from the gNB 200 via the control link of the secondary cell (serving cell C2). This prevents the secondary cell (serving cell C2) from being deactivated by the sCellDeactivationTimer.

[0135] 21 is a diagram showing this operation example. Duplicate explanations of operations similar to those in the first and second operation examples described above will be omitted.

[0136] In step S301, NCR-MT 520A establishes an RRC connection with gNB 200 and enters an RRC connected state. NCR-MT 520A is assigned the primary cell (serving cell C1) of MN 200M.

[0137] In step S302, the gNB 200 performs CA configuration or DC configuration on the NCR-MT 520A. Here, the gNB 200 configures the NCR-MT 520A with a secondary cell (serving cell C2) that controls the NCR-Fwd 510A. This configuration includes a setting timer value for the sCellDeactivationTimer. This configuration may include information specifying whether to restart the sCellDeactivationTimer when an NCR control signal (L1 / L2 signal), in particular, a DCI for NCR control, is received. This information may include the cell ID of the secondary cell (serving cell C2) and / or the identifier of the NCR-Fwd 510A.

[0138] In step S303, gNB200 sends an activation instruction for the secondary cell (serving cell C2) to NCR-MT520A.

[0139] In step S304, in response to receiving the activation instruction, the NCR-MT 520A (or the NCR device 500A) activates the secondary cell (serving cell C2) and the NCR-Fwd 510A. The NCR-MT 520A also starts the sCellDeactivationTimer set for the secondary cell (serving cell C2) in step S302.

[0140] In step S306, gNB200 transmits an NCR control signal (L1 / L2 signal) to NCR-MT520A on the control link in the secondary cell (serving cell C2).

[0141] In step S307, the NCR-MT 520A controls the NCR-Fwd 510A in response to the NCR control signal. In addition, in response to receiving the NCR control signal (L1 / L2 signal), the NCR-MT 520A restarts the sCellDeactivationTimer set for the secondary cell (serving cell C2) in step S302.

[0142] Thereafter, when the sCellDeactivationTimer expires (step S308: YES), the NCR-MT 520A deactivates the secondary cell (serving cell C2). The NCR-MT 520A (or the NCR device 500A) may also deactivate the corresponding NCR-Fwd 510A.

[0143] (1.10.4) Fourth Operation Example Using Multiple Serving Cells as a Relay Device In this operation example, the NCR-MT 520A detects that a failure has occurred in the control link (i.e., the secondary cell). The NCR-MT 520A transmits information about the detected failure to the gNB 200 on the primary cell. This allows the gNB 200 to understand that a failure has occurred in the control link.

[0144] 22 is a diagram showing this operation example. Duplicate explanations of operations similar to those in the first to third operation examples described above will be omitted.

[0145] In step S401, the NCR-MT 520A establishes an RRC connection with the gNB 200 and enters an RRC connected state. The NCR-MT 520A is assigned the primary cell (serving cell C1) of the MN 200M.

[0146] In step S402, the gNB200 performs CA configuration or DC configuration for the NCR-MT520A. This configuration may include configuration related to control link monitoring (e.g., a threshold for the quality of the control link). Here, the gNB200 configures the NCR-MT520A with a secondary cell (serving cell C2) that controls the NCR-Fwd510A.

[0147] In step S403, the gNB 200 transmits an activation instruction for the secondary cell (serving cell C2) to the NCR-MT 520A. In response to receiving the activation instruction, the NCR-MT 520A activates the secondary cell (serving cell C2) and the NCR-Fwd 510A.

[0148] In step S404, the NCR-MT 520A monitors the reception quality of the reference signal (SSB and / or CSI-RS) received on the control link. The NCR-MT 520A may perform this monitoring only if configured by the gNB 200. The reception quality may be RSRP / RSRQ / SINR of the control link.

[0149] In step S405, the NCR-MT 520A determines whether a failure in the control link has been detected. The NCR-MT 520A may determine whether a failure equivalent to a radio link failure (RLF) has occurred in the control link. The NCR-MT 520A may determine that a failure has occurred when the measured reception quality falls below a threshold. The threshold may be set by the gNB 200.

[0150] If it is determined that a control link failure has been detected (step S405: YES), in step S406, the NCR-MT 520A notifies the gNB 200 of control link failure information on the primary cell. For example, the NCR-MT 520A transmits an RRC message, such as an NCR Failure Information message, to the gNB 200. The gNB 200 receives the message. The message may include an identifier of the NCR-Fwd 510A corresponding to the control link in which the failure has occurred, an identifier of the secondary cell, and / or information on the frequency in which the failure has occurred.

[0151] (1.11) Operation of Relay Device Regarding Fault Handling The following describes the operation of the NCR device 500A according to the embodiment regarding fault handling. In the following embodiment, the NCR device 500A does not need to be configured with multiple serving cells. The NCR device 500A may be configured with multiple serving cells.

[0152] As described above, the NCR-Fwd 510A relays radio signals transmitted between the gNB 200 and the UE 100. The NCR-MT 520A controls the NCR-Fwd 510A by wireless communication with the gNB 200 via a control link. Here, the NCR-MT 520A performs predetermined control in response to the failure when it detects that a failure has occurred in the control link or the NCR-Fwd 510A. Note that, as described above, when multiple serving cells are configured in the NCR device 500A, the NCR-MT 520A may transmit control link failure information or NCR-Fwd 510A failure information to the gNB 200 on the primary cell.

[0153] (1.11.1) First Operational Example for Dealing with a Fault In this operational example, the NCR-MT 520A detects that a fault has occurred in the control link. The NCR-MT 520A stops the operation of the NCR-Fwd 510A in response to the occurrence of the fault in the control link. If a fault occurs in the control link, problems such as interference may occur if the NCR-Fwd 510A is operating in an uncontrolled state. Therefore, by stopping the operation of the NCR-Fwd 510A, such problems can be avoided. The NCR-MT 520A may also detect that the fault in the control link has been resolved. The NCR-MT 520A may also send a notification to the gNB 200 in response to the resolution of the fault.

[0154] 23 is a diagram showing this operation example. Duplicate explanations of operations similar to those in the above-described embodiment will be omitted.

[0155] In step S501, the NCR-MT 520A establishes an RRC connection with the gNB 200 and enters an RRC connected state. The gNB 200 may transmit an NCR control signal (L1 / L2 signal) to the NCR-MT 520A over the control link. The NCR-MT 520A controls the NCR-Fwd 510A in accordance with the NCR control signal.

[0156] In step S502, the NCR-MT 520A may monitor the reception quality of the reference signal (SSB and / or CSI-RS) received on the control link. The NCR-MT 520A may perform this monitoring only when configured by the gNB 200. The reception quality may be RSRP / RSRQ / SINR of the control link.

[0157] In step S503, the NCR-MT 520A determines whether a failure in the control link has been detected. The NCR-MT 520A may determine whether a failure equivalent to a radio link failure (RLF) has occurred in the control link. The NCR-MT 520A may determine that a failure has occurred when the measured reception quality falls below a threshold. The threshold may be set by the gNB 200.

[0158] For example, NCR-MT520A may determine that a control link failure has been detected when any of the following events occur: - A failure equivalent to an RLF occurs in the control link; - An RLF occurs in the primary cell; - RRC Reestablishment is initiated; - MCG Failure Information regarding an MCG failure is sent to gNB200; - SCG Failure Information regarding an SCG failure is sent to gNB200; - Transition to RRC idle state or RRC inactive state (e.g., RRC Reestablishment fails); - Connecting to a cell other than the current serving cell.

[0159] If it is determined that a control link failure has been detected (step S503: YES), in step S504, the NCR-MT 520A (or the NCR device 500A) stops the operation of the NCR-Fwd 510A (i.e., the relay operation of the wireless signal).

[0160] Thereafter, in step S505, the NCR-MT 520A may determine whether the failure in the control link has been resolved (returned to normal).

[0161] If it is determined that the control link failure has been resolved (step S505: YES), in step S506, the NCR-MT 520A may send a notification to the gNB 200 indicating that the NCR-Fwd 510A is out of operation. In response to receiving the notification, the gNB 200 may again configure and control the NCR device 500A. The gNB 200 may control the NCR device 500A to restore the previously configured and controlled state (i.e., reactivate the NCR-Fwd 510A).

[0162] (1.11.2) Second operation example for dealing with failures In this operation example, the gNB200 sets the contents of predetermined control (i.e., control when a failure occurs) for the NCR-Fwd510A to the NCR-MT520A. The NCR-MT520A detects that a failure has occurred in the control link. In response to the occurrence of a failure in the control link, the NCR-MT520A controls the contents set by the gNB200 to the NCR-Fwd510A.

[0163] For example, if the gNB 200 is configured to periodically perform a predetermined operation on the NCR device 500A, a control method may be used in which the operation of the NCR-Fwd 510A continues even if a failure occurs in the control link. Therefore, the gNB 200 may set the NCR-MT 520A to determine whether or not to continue the operation of the NCR-Fwd 510A when a failure occurs in the control link.

[0164] 24 is a diagram showing this operation example. Duplicate explanations of operations similar to those in the above-described embodiment will be omitted.

[0165] In step S601, NCR-MT520A establishes an RRC connection with gNB200 and enters the RRC connected state.

[0166] In step S602, the gNB 200 transmits to the NCR-MT 520A configuration information indicating the control content of the NCR-Fwd 510A when a control link failure occurs. The gNB 200 may include the configuration information in an RRC message (e.g., an RRC Reconfiguration message) and transmit it to the NCR-MT 520A. The NCR-MT 520A receives the configuration information. The gNB 200 may also transmit an NCR control signal (L1 / L2 signal) to the NCR-MT 520A over the control link. The NCR-MT 520A controls the NCR-Fwd 510A in accordance with the NCR control signal.

[0167] The setting information in step S602 may include information specifying, as the control content when a failure occurs in the control link, one of stopping the operation of the NCR-Fwd 510A, discarding the setting of the NCR-Fwd 510A, or continuing the operation of the NCR-Fwd 510A. If the operation of the NCR-Fwd 510A is to be continued, the setting information may include an NCR control signal indicating the beamforming method when a failure occurs in the control link.

[0168] In step S603, the NCR-MT 520A may monitor the reception quality of the reference signal (SSB and / or CSI-RS) received on the control link.

[0169] In step S604, the NCR-MT 520A determines whether or not a failure in the control link has been detected by the method described above.

[0170] If it is determined that a control link failure has been detected (step S604: YES), in step S605, the NCR-MT 520A performs the control set in step S602 on the NCR-Fwd 510A. For example, the NCR-MT 520A (or the NCR device 500A) may continue the operation of the NCR-Fwd 510A in accordance with the already set and controlled contents. The NCR-MT 520A may continue the operation of the NCR-Fwd 510A in accordance with the NCR control signal set in step S602.

[0171] The operations in steps S606 and S607 are the same as those in the above-described embodiment.

[0172] (1.11.3) Third operation example for dealing with failures In this operation example, NCR-MT 520A detects that a failure has occurred in NCR-Fwd 510A (for example, NCR-Fwd 510A has failed). In response to the occurrence of a failure in NCR-Fwd 510A, NCR-MT 520A transmits failure information of NCR-Fwd 510A to gNB 200.

[0173] 25 is a diagram showing this operation example. Duplicate explanations of operations similar to those in the above-described embodiment will be omitted.

[0174] In step S701, NCR-MT 520A establishes an RRC connection with gNB 200 and enters an RRC connected state. gNB 200 may configure NCR-MT 520A to monitor NCR-Fwd 510A. In addition, gNB 200 may transmit an NCR control signal (L1 / L2 signal) to NCR-MT 520A over the control link. NCR-MT 520A controls NCR-Fwd 510A in accordance with the NCR control signal.

[0175] In step S702, the NCR-MT 520A may monitor the operation of the NCR-Fwd 510A. For example, the NCR-MT 520A may monitor at least one of the load state, control delay time (control response time), and heat generation amount of the NCR-Fwd 510A.

[0176] In step S703, the NCR-MT 520A determines whether a failure in the NCR-Fwd 510A has been detected. For example, the NCR-MT 520A may determine that a failure in the control link has been detected when any of the following events occurs: A failure has occurred in the NCR-Fwd 510A. The processing of the NCR-Fwd 510A has not kept up with the setting and control from the gNB 200. For example, the control of the NCR-Fwd 510A could not be performed in response to an NCR control signal from the gNB 200. The load on the NCR-Fwd 510A (for example, the usage rate of hardware resources) has increased above a threshold. The threshold may be set by the gNB 200. - A failure has occurred in the control link. - An invalid control value has been received in an NCR control signal (L1 / L2 signal) and / or an RRC Reconfiguration message from the gNB 200. For example, this may be the reception of a control value (weight, etc.) that is not supported by the NCR-Fwd 510A.

[0177] If it is determined that a failure of the NCR-Fwd 510A has been detected (step S703: YES), in step S704, the NCR-MT 520A transmits failure information regarding the detected failure to the gNB 200. The gNB 200 requests the failure information. For example, the NCR-MT 520A may transmit an RRC message including the failure information, such as a message such as NCR Failure Information or a UE Assistance Information message, to the gNB 200.

[0178] The message may include at least one of the following information elements: - Information element indicating the occurrence of a failure in the NCR-Fwd 510A - Information element indicating a processing delay, load increase, or overheating in the NCR-Fwd 510A - Information element indicating the occurrence of a failure in the control link - Desired setting / control value of the NCR-Fwd 510A. For example, this may be a preference value for the upper limit of the number of antennas to be controlled and / or the upper limit of the frequency bandwidth. The gNB 200 may change the setting / control for the NCR device 500A in accordance with the desired setting / control value - An identifier of the NCR-Fwd 510A in which the failure occurred.

[0179] Upon receiving the fault information of step S704, gNB200 may send information to NCR-MT520A specifying one of the following control contents for dealing with the fault: stopping the operation of NCR-Fwd510A, discarding the settings of NCR-Fwd510A, or continuing the operation of NCR-Fwd510A.

[0180] Thereafter, in step S705, the NCR-MT 520A may determine whether the failure in the NCR-Fwd 510A has been resolved (returned to normal).

[0181] If it is determined that the failure of the NCR-Fwd 510A has been resolved (step S705: YES), in step S706, the NCR-MT 520A may transmit a notification indicating that the failure of the NCR-Fwd 510A has been resolved to the gNB 200. The notification may include an identifier of the NCR-Fwd 510A whose failure has been resolved.

[0182] (2) Second embodiment Next, the second embodiment will be described, mainly focusing on the differences from the first embodiment. The overview of the mobile communication system 1 and the configuration of the gNB 200 according to the second embodiment are the same as those of the first embodiment.

[0183] 26, the relay device according to the second embodiment is a Reconfigurable Intelligent Surface (RIS) device 500B that changes the propagation direction of an incident radio wave (wireless signal) by reflection or refraction. The "NCR" in the first and second embodiments can be read as "RIS."

[0184] RIS is a type of repeater (hereinafter also referred to as "RIS-Fwd") that can perform beamforming (directivity control) similar to NCR by changing the properties of a metamaterial. In the case of RIS, the range (distance) of the beam may also be changed by controlling the reflection direction and / or refraction direction of each unit element. For example, the RIS may be configured to control the reflection direction and / or refraction direction of each unit element and to focus (direct the beam) on a nearby UE or a distant UE.

[0185] The RIS device 500B has a new UE (hereinafter referred to as "RIS-MT") 520B, which is a control terminal for controlling the RIS-Fwd 510B. The RIS-MT 520B establishes a wireless connection with the gNB 200 and performs wireless communication with the gNB 200, thereby controlling the RIS-Fwd 510B in cooperation with the gNB 200. The RIS-Fwd 510B may be a reflective RIS. Such a RIS-Fwd 510B changes the propagation direction of incident radio waves by reflecting the radio waves. Here, the reflection angle of the radio waves is variably settable. The RIS-Fwd 510B reflects radio waves incident from the gNB 200 toward the UE 100. The RIS-Fwd 510B may be a transparent RIS. Such a RIS-Fwd 510B changes the propagation direction of the radio waves by refracting the incident radio waves. Here, the refraction angle of the radio wave can be variably set.

[0186] FIG. 27 is a diagram showing an example configuration of a RIS-Fwd (repeater) 510B and a RIS-MT (control terminal) 520B according to the second embodiment. The RIS-MT 520B includes a receiver 521, a transmitter 522, and a controller 523. This configuration is similar to that of the first embodiment. The RIS-Fwd 510B includes a RIS 511B and a RIS controller 512B. The RIS 511B is a metasurface constructed using a metamaterial. For example, the RIS 511B is constructed by arranging structures that are very small relative to the wavelength of radio waves in an array. By making the structures different shapes depending on their placement, it is possible to arbitrarily design the direction and / or beam shape of the reflected waves. The RIS 511B may also be a transparent dynamic metasurface. The RIS 511B may be configured by overlaying a transparent glass substrate on a transparent metasurface substrate on which a large number of small structures are regularly arranged, and by slightly moving the overlaid glass substrate, it may be possible to dynamically control three patterns: a mode that transmits incident radio waves, a mode that transmits some of the radio waves and reflects some of them, and a mode that reflects all of the radio waves. The RIS control unit 512B controls the RIS 511B in response to a RIS control signal from the control unit 523 of the RIS-MT 520B. 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-MT 520B and drives the actuator in response to the RIS control signal.

[0187] (3) Other Embodiments In the above-described embodiment, an example in which the gNB 200 controls the NCR device 500A has been described. However, the NCR device 500A (NCR-MT 520A) may autonomously control the NCR-Fwd 510A based on settings from the gNB 200. FIG. 28 is a diagram showing an example of beam sweeping according to another embodiment. The gNB 200 transmits multiple beams (in the illustrated example, beams SSB3 to SSB5) with the same transmission weight toward the NCR device 500A for the backhaul link. The NCR device 500A (NCR-Fwd 510A) autonomously transmits the multiple beams (beams SSB3 to SSB5) with different transmission weights in different directions for the access link. Under such assumptions, when a failure occurs, the NCR device 500A (NCR-MT520A) may autonomously control the NCR-Fwd510A based on settings from the gNB200.

[0188] The above-described operational flows are not limited to being implemented independently, but can also be implemented by combining two or more operational flows. For example, some steps of one operational flow may be added to another operational flow, or some steps of one operational flow may be replaced with some steps of another operational flow. In each flow, it is not necessary to execute all steps, and only some steps may be executed.

[0189] 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). The base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU (Distributed Unit) of the IAB node.

[0190] A program may be provided that causes a computer to execute each process performed by the UE100 (NCR-MT520A, RIS-MT520B) or the gNB200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, the program can be installed 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, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by the UE100 or the gNB200 may be integrated, and at least a portion of the UE100 or the gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0191] As used in this disclosure, the terms "based on" and "depending on / in response to" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "depending only on" and "depending at least in part on." The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Additionally, the term "or," as used in this disclosure, is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0192] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention.

[0193] This application claims priority to U.S. Provisional Application No. 63 / 395,931 (filed August 8, 2022), the entire contents of which are incorporated herein by reference.

[0194] (4) First Supplementary Note The following is a supplementary note regarding the features of the above-described embodiment.

[0195] (Supplementary Note 1) A communication method using a relay device in a mobile communication system, comprising: a step in which a repeater included in the relay device relays a radio signal of a predetermined frequency transmitted between a base station and a user device; and a step in which a control terminal included in the relay device controls the repeater by performing radio communication with the base station, wherein a plurality of serving cells including a cell corresponding to the predetermined frequency are set in the control terminal by the base station.

[0196] (Supplementary Note 2) The communication method according to Supplementary Note 1, wherein the plurality of serving cells include a primary cell and a secondary cell, and the cell corresponding to the predetermined frequency is the secondary cell.

[0197] (Supplementary Note 3) The communication method according to Supplementary Note 2, further comprising: the control terminal receiving, from the base station, an activation instruction to activate the secondary cell; and the control terminal activating operation of the repeater in response to receiving the activation instruction.

[0198] (Supplementary Note 4) The communication method according to Supplementary Note 2 or 3, further comprising: the control terminal receiving, from the base station, a deactivation instruction to deactivate the secondary cell; and the control terminal deactivating operation of the repeater in response to receiving the activation instruction.

[0199] (Supplementary Note 5) The communication method according to any one of Supplementary Notes 2 to 4, wherein the base station is a master node that manages the primary cell, the secondary cell is managed by a secondary node different from the master node, and the master node further comprises a step of transmitting information about the relay device to the secondary node over a network interface.

[0200] (Supplementary Note 6) The communication method according to any one of Supplementary Notes 2 to 5, wherein the primary cell is used for a radio resource control (RRC) connection between the base station and the control terminal, and the secondary cell is used for a control link between the base station and the control terminal.

[0201] (Supplementary Note 7) The communication method according to Supplementary Note 6, further comprising the step of: the control terminal receiving, from the base station, an RRC message including configuration information for configuring the secondary cell; and the configuration information including information for associating the secondary cell with the repeater.

[0202] (Supplementary Note 8) The communication method according to Supplementary Note 6 or 7, further comprising a step in which the control terminal receives a control signal for controlling the repeater from the base station via the control link, the control signal including identification information for identifying the repeater.

[0203] (Supplementary Note 9) The communication method according to any one of Supplementary Notes 6 to 8, further comprising the step of the base station avoiding setting a deactivation timer for the secondary cell that measures a predetermined time, the deactivation timer being a timer for deactivating the secondary cell in response to a period of time during which no data communication has occurred in the secondary cell continuing for the predetermined time.

[0204] (Supplementary Note 10) The communication method described in any of Supplementary Notes 6 to 8, further comprising the steps of: the base station setting a deactivation timer for the secondary cell that measures a predetermined time; the control terminal receiving a control signal for controlling the repeater from the base station via the control link; and restarting the deactivation timer in response to receiving the control signal, wherein the deactivation timer is a timer for deactivating the secondary cell in response to a period of time in which no data communication has occurred in the secondary cell continuing for the predetermined period of time.

[0205] (Supplementary Note 11) The communication method according to any one of Supplementary Notes 6 to 10, further comprising the steps of: the control terminal detecting that a failure has occurred in the control link; and the control terminal transmitting information relating to the failure to the base station on the primary cell.

[0206] (Supplementary Note 12) A relay device used in a mobile communication system, comprising: a repeater that relays a radio signal of a predetermined frequency transmitted between a base station and a user device; and a control terminal that controls the repeater by performing radio communication with the base station, wherein a plurality of serving cells including a cell corresponding to the predetermined frequency are set in the control terminal by the base station.

[0207] (Supplementary Note 13) A base station used in a mobile communication system, comprising: a communication unit that performs wireless communication with a control terminal that controls a repeater that relays a radio signal of a predetermined frequency transmitted between the base station and a user device; and a control unit that sets a plurality of serving cells, including a cell corresponding to the predetermined frequency, in the control terminal.

[0208] (5) Annex 2 Introduction RAN#94e agreed to a new study item on Network Controlled Repeaters (NCR). The objectives of this study are as follows:

[0209] The side control information required for the network controlled repeater is considered and defined as follows (including maximum transmit power assumptions): - Beamforming information - Timing information for aligning the transmit / receive boundary of the network controlled repeater - Information on UL-DL TDD settings - ON-OFF information for efficient interference management and improved energy efficiency - Power control information for efficient interference management (as a second priority) The L1 / L2 signaling (including its configuration) for transmitting the side control information is considered and defined.

[0210] The following aspects of network controlled repeater management shall be considered: - Identification and approval of network controlled repeaters. NOTE 2: Coordination with SA3 may be required.

[0211] This appendix discusses the initial challenges for RAN2 regarding NCR.

[0212] Discussion According to the NCR Model SID, the scenarios and assumptions are described as follows:

[0213] The study on NR network-controlled repeaters is to focus on the following scenarios and assumptions: - Network-controlled repeaters are in-band RF repeaters used to extend network coverage in the FR1 and FR2 bands. It is under consideration that FR2 deployments may be prioritized in both outdoor-to-indoor O2I scenarios. - Limited to single-hop, stationary network-controlled repeaters - Network-controlled repeaters are transparent to the UE - Network-controlled repeaters can simultaneously maintain links with the gNB and with the UE Note 1: Cost efficiency is an important consideration for network-controlled repeaters.

[0214] RAN1#109e agreed to the NCR model as follows:

[0215] Agreements The model of the network-controlled repeater in TR38.867 is shown in Figure 29 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: Side control information is for the control of at least the NCR-FW. ・NCR-Fwd is defined as a functional entity that performs amplification and forwarding of UL / DL RF signals between the gNB and the UE via the backhaul link and the access link. The operation of the NCR-Fwd is controlled according to the side control information received from the gNB.

[0216] According to the above description, since NCR-Fwd is an in-band RF repeater, there should be no impact on RAN2.

[0217] Observation 1: NCR-Fwd is an RF repeater and is outside the range of RAN2.

[0218] On the other hand, the NCR-MT maintains a control link with the gNB and communicates side control information. The NCR-MT can be considered a special UE type similar to the IAB-MT. This means that it naturally requires support for protocols such as NAS, RRC, PDCP, RLC, MAC, and PHY. As a starting point, the IAB-MT is considered a good reference for modeling the NCR-MT. However, since the BAP sublayer assumes only single-hop, stationary, network-controlled repeaters, it is clear that it is not required for the NCR-MT. Control link coverage extension should be achieved by other means, such as using FR1 or RF repeaters.

[0219] Proposal 1: As a starting point, RAN2 should consider IAB-MT as the basis for the NCR-MT model, and the BAP sublayer is not supported in NCR-MT.

[0220] The IAB-MT can send and receive its own traffic, such as OAM traffic. The same principle applies to the NCR-MT, since the NCR may implement OAM functions. Therefore, the NCR-MT must support not only SRB (side control information, RRC configuration, NAS connections, etc.) but also DRB (own traffic, etc.), and the establishment of DRB may be optional.

[0221] Proposal 2: It should be agreed that NCR-MT will support both SRB and DRB.

[0222] As shown in Figure 30, gNB instructions (e.g., side control information) are considered to be used by the NCR-MT to control the NCR-Fwd (e.g., beamforming, ON / OFF control, power control, etc.) via an internal interface, regardless of whether such an internal interface is specified.

[0223] Observation 2: The NCR-MT receives instructions from the gNB (e.g., via side control information) and controls the NCR-Fwd accordingly.

[0224] NCR Management Aspects Identification, Authentication and Access Control According to the SID, RAN2 is responsible for considering management aspects.

[0225] The following aspects of network controlled repeater management are considered: - Identification and authentication of network controlled repeaters NOTE 2: Coordination with SA3 may be required.

[0226] When considering IAB-MT as the basis as in Proposal 1, the NCR is considered as a network node, and therefore the same access control mechanism is considered applicable to the NCR-MT.

[0227] The gNB provides an SIB indication to allow NCR-MT access, such as an 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 following IEs related to reserved cells: - Cell Reserved For Future Use IE - Cell Reserved For Other Use IE (for cell barring decisions) - Cell Reserved For Operator Use IE (if the NCR-MT supports NPN). - The NCR-MT sends an NCR indication upon RRC setup completion, such as the IAB Node Indication IE.

[0228] Proposal 3: If NCR is considered as a network node, RAN2 should agree to reuse the access control mechanism of IAB-MT, i.e., the gNB provides SIB indication and NCR-MT ignores IEs related to cell blocking and cell reservation.

[0229] If the NCR-MT is viewed as similar to the IAB-MT from the perspective of RAN2, RAN2 may assume that the higher layer mechanisms of the IAB-MT are also reused for the NCR-MT, e.g., with regard to authentication.

[0230] Observation 3: RAN2 can assume that the higher layer mechanisms of IAB-MT are reused for NCR-MT, for example in terms of authentication.

[0231] Another issue regarding NCR capability signaling management is how the gNB knows the capabilities of the NCR-Fwd, such as the operating frequency, number and resolution of beamforming, output power and dynamic range, etc., since the NCR-Fwd is an RF repeater, i.e., without protocol support. It is very simple for the NCR-MT to inform the gNB of the capabilities of the connected NCR-Fwd in addition to its own (i.e., NCR-MT) capabilities.

[0232] Proposal 4: RAN2 should agree that NCR-MT notifies gNB of the capabilities of NCR-Fwd. Further consideration is needed regarding the capabilities to be reported.

[0233] Multi-Beam NCR It is also worth considering whether the NCR can handle multiple beams, as shown in Figure 31. This is expected to improve spectral efficiency, enhance coverage, and allow scheduling flexibility for multiple UEs.

[0234] A simple RF repeater does not have resource block selectivity and amplifies and forwards 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 that the Rel-18 NCR supports the implementation of such advanced RF repeaters.

[0235] Proposal 5: RAN2 should agree to manage the NCR, which allows the gNB to process multiple beams simultaneously for different UEs.

[0236] If multi-beam NCR is supported, from the RAN2 point of view, there may be a discussion about whether one NCR node (or one NCR-MT) can support multiple NCR-Fwds. Similarly, an additional consideration may be whether one NCR-Fwd can control multiple "antenna sets." These options are shown in Figure 32.

[0237] 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 31). In the case of multiple NCR-Fwds, the NCR must simultaneously process different weights instructed by the gNB for each NCR-Fwd.

[0238] Another possible scenario is that the NCR is controlled by multiple gNBs, for example, when the NCR is deployed at the cell edge, in which case multiple NCR-Fwds are required to process different beams for different access links belonging to different gNBs.

[0239] These cases may affect the design of NCR management and side control information, so RAN2 needs to discuss management models to allow various implementations of multi-beam NCR.

[0240] Note: RAN1 decides whether multiple NCR-Fwds are co-located (e.g., for spatial diversity gain). Even if multiple Fwds are not co-located, RAN1 should assume that the control link and backhaul link share the same radio channel conditions. This is implied in the decision made in RAN#96.

[0241] Proposal 6: RAN2 should discuss the management model for repeaters with multiple beams, for example, whether one NCR-MT can control multiple NCR-Fwds, or whether one NCR-Fwd can support multiple antenna sets.

[0242] Side Control Information RAN1 has discussed the overall concept and function of side control information, such as beam information, TDD UL / DL configuration, DL reception and UL transmission timing, and ON-OFF information. From the RAN2 perspective, it is assumed that dynamic and semi-static control may be indicated by DCI and MAC CE (or a combination of these), respectively. Furthermore, static configuration should be performed by RRC. For detailed design of side control information, RAN2 needs to wait for the progress of RAN1.

[0243] Observation 4: Side control information may need to extend DCI, MAC CE, and / or RRC signaling. RAN2 needs to wait for further developments of RAN1.

[0244] Deployment Assumptions In RAN#96, multi-frequency support was discussed, but it was decided that the operating frequency of the control link would be limited to the same as the backhaul link.

[0245] RAN Chair: RAN1 discussions will focus on in-band only.

[0246] It is believed that the intention is to simplify the control link procedures by utilizing the same channel conditions as the backhaul link.

[0247] Observation 5: When the control link and backhaul link operate on the same frequency, the wireless channel conditions are the same.

[0248] On the other hand, it is also worth considering whether the NCR-MT can support carrier aggregation (CA) and dual connectivity (DC). For example, the NCR-MT may configure a PCell (for RRC connection) in FR1 and an SCell (for side control information) in FR2 on the same frequency, as shown in Figure 33.

[0249] The CA / DC configuration of the NCR-MT is not considered to violate the RAN plenary decision as long as the SCell for the control link operates on the same frequency as the NCR-Fwd for the backhaul link. Furthermore, the robust RRC connection on the FR1 / PCell brings various advantages, considering that the NCR is a network node. This is very similar to the CP / UP split configuration specified by the IAB.

[0250] Proposal 7: RAN2 should consider the possibility of configuring NCR-MT with Carrier Aggregation (CA) and Dual Connectivity (DC). At least one SCell should be configured to operate on the same frequency as the NCR-Fwd.

[0251] 1: Mobile communication system 100: UE 200: gNB 210: Transmitter 220: Receiver 230: Controller 240: Backhaul communication unit 500A: NCR device 500B: RIS device 511A: Wireless unit 511a: Antenna unit 511b: RF circuit 511c: Directivity control unit 512A: NCR control unit 512B: RIS control unit 521: Receiver 522: Transmitter 523: Controller 530: Interface

Claims

1. A communication method using a relay device in a mobile communication system, comprising: A repeater included in the relay device relays a radio signal of a predetermined frequency transmitted between a network node and a user equipment; a control terminal included in the relay device controls the relay by wirelessly communicating with the network node; In the control terminal, a plurality of serving cells including a cell corresponding to the predetermined frequency are set by the network node. Communication methods.

2. The plurality of serving cells includes a primary cell and a secondary cell, The cell corresponding to the predetermined frequency is the secondary cell. The communication method according to claim 1 .

3. receiving, by the control terminal, an activation indication from the network node to activate the secondary cell; and activating operation of the repeater by the control terminal in response to receiving the activation instruction. The communication method according to claim 2 .

4. receiving, by the control terminal, a deactivation indication from the network node to deactivate the secondary cell; and the control terminal deactivating operation of the repeater in response to receiving the activation instruction. The communication method according to claim 2 .

5. the network node is a master node that manages the primary cell, The secondary cell is managed by a secondary node different from the master node, The method further includes the step of: transmitting information about the relay device to the secondary node over a network interface by the master node. The communication method according to claim 2 .

6. The primary cell is used for a radio resource control (RRC) connection between the network node and the control terminal; The secondary cell is used for a control link between the network node and the control terminal. A communication method according to any one of claims 2 to 5.

7. The control terminal further comprises receiving an RRC message from the network node, the RRC message including configuration information for configuring the secondary cell; The configuration information includes information for associating the secondary cell with the repeater. The communication method according to claim 6.

8. The control terminal further comprises receiving, via the control link, a control signal for controlling the repeater from the network node; The control signal includes identification information for identifying the repeater. The communication method according to claim 6.

9. The method further comprises: the network node avoiding setting a deactivation timer for the secondary cell, the deactivation timer timing a predetermined time; The deactivation timer is a timer for deactivating the secondary cell in response to a period of time during which no data communication has occurred in the secondary cell continuing for the predetermined period of time. The communication method according to claim 6.

10. said network node configuring a deactivation timer for said secondary cell, said deactivation timer timing a predetermined time; said control terminal receiving, via said control link, a control signal for controlling said repeater from said network node; and restarting the deactivation timer in response to receiving the control signal. The deactivation timer is a timer for deactivating the secondary cell in response to a period of time during which no data communication has occurred in the secondary cell continuing for the predetermined period of time. The communication method according to claim 6.

11. The control terminal detects that a failure has occurred in the control link; and the control terminal transmitting information regarding the failure to the network node on the primary cell. The communication method according to claim 6.

12. A relay device for use in a mobile communication system, comprising: a repeater that repeats a radio signal of a predetermined frequency transmitted between a network node and a user device; a control terminal that controls the repeater by wirelessly communicating with the network node; In the control terminal, a plurality of serving cells including a cell corresponding to the predetermined frequency are set by the network node. Relay device.

13. A network node for use in a mobile communication system, comprising: a communication unit that performs wireless communication with a control terminal that controls a repeater that relays a wireless signal of a predetermined frequency transmitted between a network node and a user device; A control unit that sets a plurality of serving cells including a cell corresponding to the predetermined frequency to the control terminal. Network node.