Communication method and relay device

Abstract

A communication method using a relay device in a mobile communication system includes: a relay included in the relay device relays a radio signal transmitted between a base station and a user equipment; a control terminal included in a relay device controls a repeater by performing wireless communication with a base station via a control link; the control terminal detects that a fault has occurred in the control link or the repeater; and in response to the failure, controlling the terminal to perform predetermined control.

Description

Technical Field

[0001] The present disclosure relates to a communication method and a relay device used in a mobile communication system. Background Art

[0002] In recent years, the fifth generation (5G) mobile communication system has attracted much attention. New Radio (NR), which is the radio access technology of the 5G system, allows broadband transmission via a high frequency band compared to Long Term Evolution (LTE), which is the fourth generation radio access technology.

[0003] Since radio signals (radio waves) in high frequency bands such as the millimeter wave band or the terahertz wave band have high linearity, there is a problem that the coverage of the base station is reduced. In order to solve this problem, a repeater device has attracted attention. A repeater device is a relay device for relaying radio signals between a base station and a user device, and can be controlled from a network (see, for example, non-patent document 1). Such a repeater device can expand the coverage of a base station by, for example, amplifying a radio signal received from a base station and transmitting the radio signal by directional transmission, while preventing interference from occurring.

[0004] Reference List

[0005] Non-patent literature

[0006] Non-patent document 1: 3GPP contribution: RP-213700, "New SI: Study on NR Network-controlled Repeaters" Summary of the invention

[0007] In a first aspect, a communication method using a relay device in a mobile communication system includes: a repeater included in the relay device relays a radio signal sent between a base station and a user equipment; a control terminal included in the relay device controls the repeater by performing wireless communication with the base station via a control link; the control terminal detects that a fault has occurred in the control link or the repeater; and in response to the fault, the control terminal performs a predetermined control.

[0008] In a second aspect, a relay device used in a mobile communication system includes: a repeater configured to relay a radio signal transmitted between a base station and a user equipment; and a control terminal configured to control the repeater by performing wireless communication with the base station via a control link. When the control terminal detects that a fault has occurred in the control link or the repeater, the control terminal performs a predetermined control in response to the fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1is a diagram showing a configuration of a mobile communication system according to an embodiment.

[0010] Figure 2 is a diagram showing a configuration of a protocol stack of a radio interface of a user plane processing data.

[0011] Figure 3 is a diagram showing a configuration of a protocol stack of a radio interface of a control plane that processes signaling (control signals).

[0012] Figure 4 : is a diagram showing an example of an application scenario of the relay device (NCR device) according to the first embodiment.

[0013] Figure 5 : is a diagram showing an example of an application scenario of the relay device (NCR device) according to the first embodiment.

[0014] Figure 6 : is a diagram showing an example of a control method of a relay device (NCR device) according to the first embodiment.

[0015] Figure 7 is a diagram showing a configuration example of a protocol stack in a mobile communication system including a relay device (NCR device) according to the first embodiment.

[0016] Figure 8 is a diagram showing a configuration example of a relay device (NCR device) according to the first embodiment.

[0017] Fig. 9 is a diagram showing a configuration example of a base station (gNB) according to an embodiment.

[0018] Fig.10 is a diagram showing an example of downlink signaling from a base station (gNB) to a control terminal (NCR-MT) according to the first embodiment.

[0019] Fig.11 is a diagram showing an example of uplink signaling from a control terminal (NCR-MT) to a base station (gNB) according to the first embodiment.

[0020] Fig.12 is a diagram showing an example of a general operation sequence of the mobile communication system according to the first embodiment.

[0021] Fig.13 is a diagram for describing beam scanning according to the first embodiment.

[0022] Fig.14 is a diagram for describing carrier aggregation (CA).

[0023] Fig.15is a diagram used to describe dual connectivity (DC).

[0024] Fig.16 : is a diagram showing a configuration example when CA is configured for an NCR device (NCR-MT).

[0025] Fig.17 is a diagram showing a configuration example when DC is configured for an NCR device (NCR-MT).

[0026] Fig.18 is a diagram showing a first operation example in which a plurality of serving cells are used for an NCR device through CA according to the first embodiment.

[0027] Fig.19 is a diagram showing a first operation example in which a plurality of serving cells are used for an NCR device through DC according to the first embodiment.

[0028] Fig. 20 This is a diagram for describing sCellDeactivationTimer.

[0029] Fig.21 2 is a diagram showing a third operation example in which a plurality of serving cells are used for an NCR device according to the first embodiment.

[0030] Fig. 22 2 is a diagram showing a fourth operation example in which a plurality of serving cells are used for an NCR device according to the first embodiment.

[0031] Fig.23 : is a diagram showing a first operation example of the NCR apparatus handling a failure according to the first embodiment.

[0032] Fig.24 2 is a diagram showing a second operation example of the NCR apparatus handling a failure according to the first embodiment.

[0033] Fig.25 is a diagram showing a third operation example of the NCR apparatus handling a failure according to the first embodiment.

[0034] Fig.26 is a diagram for describing a relay device according to a second embodiment.

[0035] Fig. 27 is a diagram for describing a relay device according to a second embodiment.

[0036] Fig.28 is a diagram for describing an operation according to another embodiment. DETAILED DESCRIPTION

[0037] When a relay device such as a repeater device is controlled from a network, a control technology for exclusively controlling the relay device has not yet been established, and it is currently difficult to perform effective coverage extension using the relay device.

[0038] The present disclosure provides a properly controllable relay device for performing relay transmission between a base station and a user equipment.

[0039] The mobile communication system according to the embodiment is described with reference to the accompanying drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0040] (1) First Embodiment

[0041] First, the first embodiment is described. The relay device according to the first embodiment is a relay device that can be controlled from a network.

[0042] (1.1) Overview of mobile communication system

[0043] Figure 1 1 is a diagram showing a configuration of a mobile communication system according to a first embodiment. The mobile communication system 1 complies with the fifth generation system (5GS) of the third generation partnership project (3GPP) (registered trademark; the same below) standard. The following description takes 5GS as an example, but the long term evolution (LTE) system may be at least partially applied to the mobile communication system. The sixth generation (6G) system may be at least partially applied to the mobile communication system.

[0044] The mobile communication system includes a user equipment (UE) 100, a 5G radio access network (next generation radio access network (NG-RAN)) 10, and a 5G core network (5GC) 20. Hereinafter, the NG-RAN 10 may be simply referred to as the RAN 10. The 5GC 20 may be simply referred to as the core network (CN) 20.

[0045] UE 100 is a mobile wireless communication device. UE 100 may be any device as long as UE 100 is used by a user. Examples of UE 100 include a mobile phone terminal (including a smart phone) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided on a sensor, a vehicle or a device provided on a vehicle (vehicle UE), and an aircraft and a device provided on the aircraft (air UE).

[0046] The NG-RAN 10 includes a base station (referred to as a "gNB" in the 5G system) 200. The gNBs 200 are interconnected via an Xn interface which is an interface between base stations. Each gNB 200 manages one or more cells. The gNB 200 performs wireless communication with the UE 100, which has established a connection with the cell of the gNB 200. The gNB 200 has a radio resource management (RRM) function, a function of routing user data (hereinafter referred to as "data"), a measurement control function for mobility control and scheduling, and the like. "Cell" is used as a term representing the smallest unit of a wireless communication area. "Cell" is also used as a term representing a function or resource used to perform wireless communication with the UE 100. One cell belongs to one carrier frequency (hereinafter referred to as "frequency").

[0047] The gNB 200 may be divided into a central unit (CU) and a distributed unit (DU). The CU controls the DU. The CU is, for example, a unit including an upper layer included in the following protocol stack, such as an RRC layer, an SDAP layer, and a PDCP layer. The CU is connected to the core network via an NG interface as a backhaul interface. The CU is connected to a neighboring base station via an Xn interface as an interface between base stations. The DU forms a cell. The DU 202 is, for example, a unit including a lower layer included in the following protocol stack, such as an RLC layer, a MAC layer, and a PHY layer. The DU is connected to the CU via an F1 interface as a fronthaul interface.

[0048] Note that the gNB can be connected to the Evolved Packet Core (EPC) corresponding to the core network of LTE. The LTE base station can also be connected to the 5GC. The LTE base station and the gNB can be connected via an inter-base station interface.

[0049] The 5GC 20 includes an access and mobility management function (AMF) and a user plane function (UPF) 300. The AMF performs various types of mobility control, etc. for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using non-access stratum (NAS) signaling. The UPF controls data transmission. 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.

[0050] Figure 2 is a diagram showing a configuration of a protocol stack of a radio interface of a user plane processing data.

[0051] The radio interface protocol of the user plane 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.

[0052] The PHY layer performs encoding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the gNB 200 via a physical channel. Note that the PHY layer of the UE 100 receives downlink control information (DCI) transmitted from the gNB 200 through the physical downlink control channel (PDCCH). Specifically, the UE 100 performs blind decoding on the PDCCH using the radio network temporary identifier (RNTI) and obtains the successfully decoded DCI as the DCI addressed to the UE 100. The DCI transmitted from the gNB 200 is attached with CRC parity bits scrambled by the RNTI.

[0053] The gNB 200 transmits a synchronization signal block (SSB: synchronization signal / PBCH block). For example, the SSB includes four consecutive orthogonal frequency division multiplexing (OFDM) symbols, in which the primary synchronization signal (PSS), the secondary synchronization signal (SSS), the physical broadcast channel (PBCH) / master information block (MIB), and the demodulation reference signal (DMRS) of the PBCH are arranged. The bandwidth of the SSB is, for example, the bandwidth of 240 consecutive subcarriers, that is, 20RB.

[0054] The MAC layer performs priority control of data, retransmission processing by hybrid ARQ (HARQ: Hybrid Automatic Repeat Request), a random access procedure, 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 transport format (transport block size, modulation and coding scheme (MCS)) in uplink and downlink and resource blocks to be allocated to the UE 100.

[0055] The RLC layer transmits data to the RLC layer of the receiving side by using the functions of the MAC layer and the 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.

[0056] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0057] The SDAP layer performs mapping between IP flows (as the unit of Quality of Service QoS control performed by the core network) and radio bearers (as the unit of QoS control performed by the access stratum (AS)). Note that when the RAN is connected to the EPC, SDAP does not need to be provided.

[0058] Figure 3 is a diagram showing a configuration of a protocol stack of a radio interface of a control plane that processes signaling (control signals).

[0059] The protocol stack of the radio interface of the control plane includes the Radio Resource Control (RRC) layer and the Non-Access Stratum (NAS) layer, instead of Figure 2 The SDAP layer is shown.

[0060] RRC signaling for various configurations is transmitted between the RRC layer of the UE 100 and the RRC layer of the gNB 200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, reestablishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of the UE 100 and the RRC of the gNB 200, the UE 100 is in the RRC connected state. When there is no connection (RRC connection) between the RRC of the UE 100 and the RRC of the gNB 200, the UE 100 is in the RRC idle state. When the connection between the RRC of the UE 100 and the RRC of the gNB 200 is suspended, the UE 100 is in the RRC inactive state.

[0061] The NAS layer located above the RRC layer performs session management, mobility management, etc. NAS signaling is sent between the NAS layer of the UE 100 and the NAS layer of the AMF 300A. Note that the UE 100 includes an application layer in addition to the protocol of the radio interface. The layer lower than the NAS layer is called the AS layer.

[0062] (1.2) Examples of application scenarios of relay devices

[0063] Figure 4 and Figure 5 is a diagram showing an example of an application scenario of the NCR apparatus according to the first embodiment.

[0064] Compared to 4G / LTE, 5G / NR is capable of broadband transmission via high-frequency bands. Since radio signals in high-frequency bands such as the millimeter wave band or the terahertz band have high linearity, a reduction in the coverage of the gNB 200 is a problem. Figure 4 In the present embodiment, UE 100 may be located outside the coverage of gNB 200, for example, outside the area where UE 100 can directly receive radio signals from gNB 200. Due to the presence of obstacles between gNB 200 and UE 100, UE 100 may be in a state where it cannot perform communication with gNB 200 within the line of sight.

[0065] like Figure 4As shown, the repeater device (500A) is a relay device that relays radio signals between the gNB 200 and the UE 100 and can be controlled from the network. The repeater device (500A) is introduced into the mobile communication system 1. Hereinafter, such a repeater device is referred to as a network controlled repeater (NCR) device. Such a repeater device may be referred to as a smart repeater device.

[0066] For example, the NCR device 500A amplifies a radio signal (radio wave) received from the gNB 200, and transmits the radio signal through directional transmission. Specifically, the NCR device 500A receives the radio signal transmitted by the gNB 200 through beamforming. The NCR device 500A amplifies the received radio signal without demodulation / modulation, and transmits the amplified radio signal through directional transmission. Here, the NCR device 500A can transmit the radio signal with a fixed directivity (beam). The NCR device 500A can transmit the radio signal with a variable (adaptive) directional beam. This can effectively expand the coverage of the gNB 200. Although 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, the NCR device 500A can also be applied to uplink communication from the UE 100 to the gNB 200.

[0067] like Figure 5 As shown, a new UE (hereinafter, referred to as "NCR-mobile terminal MT") 520A is introduced, which is a control terminal for controlling the NCR device 500A. Specifically, the NCR device 500A includes an NCR-forwarding (Fwd) 510A and an NCR-MT 520A. The NCR-Fwd 510A is a repeater that relays radio signals transmitted between the gNB 200 and the UE 100, and more specifically, it changes the propagation state of the radio signal without demodulating or modulating the radio signal. The NCR-MT 520A performs radio communication with the gNB 200 to control the NCR-Fwd 510A. In this way, the NCR-MT 520A controls the NCR device 500A in cooperation with the gNB 200 by establishing a radio connection with the gNB 200 and performing wireless communication with the gNB 200. By doing so, effective coverage extension can be achieved using the NCR device 500A. NCR-MT 520A controls NCR device 500A according to the control from gNB 200.

[0068] The NCR-MT 520A may be configured to be separated from the NCR-Fwd 510A. For example, the NCR-MT 520A may be located near the NCR-Fwd 510A and may be electrically connected to the NCR-Fwd 510A. The NCR-MT 520A may be connected to the NCR-Fwd 510A by wire or wirelessly. The NCR-MT 520A may be configured to be integrated with the NCR-Fwd 510A. The NCR-MT 520A and the NCR-Fwd 510A may be fixedly installed at the coverage edge (cell edge) of the gNB 200, or, for example, installed on a wall surface or window of any building. The NCR-MT 520A and the NCR-Fwd 510A may be installed in, for example, a movable vehicle. One NCR-MT 520A may control multiple NCR-Fwd 510As.

[0069] exist Figure 5 In the example shown, the NCR device 500A (NCR-Fwd 510A) dynamically or semi-statically changes the beam used for transmission or reception. For example, the NCR-Fwd 510A forms a beam toward each of the UE 100a and the UE 100b. The NCR-Fwd 510A may 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 to the UE 100a by beamforming and / or transmits a radio signal received from the UE 100a to the gNB 200 by beamforming. In the communication resources between the gNB 200 and the UE 100b, the NCR-Fwd 510A transmits the radio signal received from the gNB 200 to the UE 100b by beamforming and / or transmits the radio signal received from the UE 100b to the gNB 200 by beamforming. Instead of or in addition to the beamforming, the NCR-Fwd 510A may also perform null formation (so-called null steering) to the UE 100 (not shown) that is not a communication partner and / or a neighboring gNB 200 (not shown) to suppress interference.

[0070] Figure 6 4 is a diagram showing a control method of the NCR device 500A according to the first embodiment. Figure 6As shown, NCR-Fwd 510A relays radio signals (referred to as "UE signals") between gNB 200 and UE 100. UE signals include uplink signals (referred to as "UE-UL signals") sent from UE 100 to gNB 200 and downlink signals (referred to as "UE-DL signals") sent from gNB 200 to UE 100. NCR-Fwd 510A relays the UE-UL signals from UE 100 to gNB 200, and relays the UE-DL signals from gNB 200 to UE 100. The radio link between NCR-Fwd 510A and UE 100 is also referred to as an "access link". The radio link between NCR-Fwd 510A and gNB 200 is also referred to as a "backhaul link".

[0071] NCR-MT 520A sends and receives radio signals (referred to herein as "NCR-MT signals") to and from gNB 200. NCR-MT signals include uplink signals (referred to herein as "NCR-MT-UL signals") sent from NCR-MT 520A to gNB 200 and downlink signals (referred to herein as "NCR-MT-DL signals") sent from gNB 200 to NCR-MT 520A. NCR-MT-UL signals include signaling for controlling NCR device 500A. The radio link between NCR-MT 520A and gNB 200 is also referred to as a "control link".

[0072] The gNB 200 directs the beam to the NCR-MT 520A based on the NCR-MT-UL signal from the NCR-MT 520A. The NCR device 500A and the NCR-MT 520A are co-located, so when the frequencies of the backhaul link and the control link are the same, directing the beam to the NCR-MT 520A by the gNB 200 results in directing the beam to the NCR-Fwd 510A as well. The gNB 200 uses the beam to transmit the NCR-MT-DL signal and the UE-DL signal. The NCR-MT 520A receives the NCR-MT-DL signal. Note that when the NCR-Fwd 510A and the NCR-MT 520A are at least partially integrated with each other, the functions of transmitting and receiving or relaying the UE signal and / or the NCR-MT signal (e.g., the antenna) may be integrated together in the NCR-Fwd 510A and the NCR-MT 520A. A beam includes a transmission beam and / or a reception beam. A beam is a general term for transmission and / or reception under control to maximize the power of a transmission wave and / or a reception wave in a specific direction by adjusting / adapting an antenna weight or the like.

[0073] Figure 7is a diagram showing a configuration example of a protocol stack in the mobile communication system 1 including the 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 a radio frequency (RF) function of amplifying and relaying received radio signals, and performs directional transmission by beamforming (e.g., analog beamforming).

[0074] The NCR-MT 520A includes at least one layer (entity) selected from the group consisting of PHY, MAC, RRC, and F1-AP (application protocol). F1-AP is a fronthaul interface. The NCR-UE 100B transmits downlink signaling and / or uplink signaling (to be described below) with the gNB 200 through at least one selected from the group consisting of PHY, MAC, RRC, and F1-AP. When the NCR-MT 520A is a base station or a part of a base station, the NCR-MT 520A can communicate with the gNB 200 through an Xn AP (Xn-AP) as an interface between base stations.

[0075] (1.3) Example of relay device configuration

[0076] Figure 8 5 is a diagram showing a configuration example of an NCR device 500A as 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.

[0077] The NCR-Fwd 510A includes a radio unit 511A and an NCR controller 512A. The radio unit 511A includes an antenna 511a including a plurality of antennas (a plurality of antenna elements), an RF circuit 511b including an amplifier, and a directivity controller 511c for controlling the directivity of the antenna 511a. The RF circuit 511b amplifies and relays (transmits) a radio signal transmitted and received by the antenna 511a. The RF circuit 511b may convert a radio signal, which is an analog signal, into a digital signal, and may reconvert the digital signal into an analog signal after digital signal processing. The directivity controller 511c may perform analog beamforming through analog signal processing. The directivity controller 511c may perform digital beamforming through digital signal processing. The directivity controller 511c may perform analog and digital hybrid beamforming. The NCR controller 512A controls the radio unit 511A in response to a control signal from the NCR-MT 520A. The NCR controller 512A may include at least one processor. The NCR controller 512A may output information related to the capabilities of the NCR device 500A to the NCR-MT 520A.

[0078] NCR-MT 520A includes a receiver 521, a transmitter 522, and a controller 523. Receiver 521 performs various types of reception under the control of controller 523. Receiver 521 includes an antenna and a receiving device. The receiving device converts a radio wave (radio signal) received through the antenna into a baseband signal (received signal), and outputs the resulting signal to controller 523. Transmitter 522 performs various types of transmission under the control of controller 523. Transmitter 522 includes an antenna and a transmitting device. The transmitting device converts a baseband signal (transmitted signal) output by controller 523 into a radio signal, and transmits the resulting signal through the antenna. Controller 523 performs various types of control in NCR-MT 520A. Controller 523 includes at least one processor and at least one memory. The memory stores programs to be executed by the processor and information to be processed by the processor. The processor may include a baseband processor and a central processing unit (CPU). The baseband processor performs modulation and demodulation, encoding and decoding, etc. of the baseband signal. The CPU executes the program stored in the memory, thereby performing various types of processing. The controller 523 performs a function of at least one layer selected from the group consisting of PHY, MAC, RRC, and F1-AP.

[0079] The interface 530 electrically connects the NCR-Fwd 510A and the NCR-MT 520A. The controller 523 of the NCR-MT 520A controls the NCR-Fwd 510A via the interface 530.

[0080] In the first embodiment, the receiver 521 of the NCR-MT 520A receives signaling (downlink signaling) for controlling the NCR device 500A from the gNB 200 through 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.

[0081] In the first embodiment, the controller 523 of the NCR-MT 520A may transmit NCR capability information indicating the capability of the NCR device 500A to the gNB 200 through 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 recognize the capability of the NCR device 500A.

[0082] (1.4) Base station configuration example

[0083] Fig. 92 is a diagram showing a configuration example of a gNB 200 according to the first embodiment. The gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communicator 240.

[0084] The transmitter 210 performs various types of transmission under the control of the controller 230. The transmitter 210 includes an antenna and a transmitting device. The transmitting device converts a baseband signal (transmitting signal) output by the controller 230 into a radio signal, and transmits the resulting signal through the antenna. The receiver 220 performs various types of reception under the control of the controller 230. The receiver 220 includes an antenna and a receiving device. The receiving device converts a radio signal received through the antenna into a baseband signal (receiving signal), and outputs the resulting signal to the controller 230. The transmitter 210 and the receiver 220 can perform beamforming using multiple antennas.

[0085] The controller 230 performs various types of control of the gNB 200. The controller 230 includes at least one processor and at least one memory. The memory stores programs to be executed by the processor and information to be processed by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation and demodulation, encoding and decoding of baseband signals, etc. The CPU executes the program stored in the memory, thereby performing various types of processing.

[0086] The backhaul communicator 240 is connected to the neighboring base station via the inter-base station interface. The backhaul communicator 240 is connected to the AMF / UPF 300 via the interface between the base station and the core network. Note that the gNB may include a central unit (CU) and a distributed unit (DU) (ie, the functions are divided), and these two units may be connected via the F1 interface.

[0087] In the first embodiment, the transmitter 210 of the gNB 200 transmits signaling (downlink signaling) for controlling the NCR-Fwd 510A to the NCR-MT 520A through 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 capability of the NCR device 500A from the NCR-MT 520A through wireless communication.

[0088] (1.5) Example of downlink signaling

[0089] Fig.10 is a diagram showing an example of downlink signaling from gNB 200 to NCR-MT 520A according to the first embodiment.

[0090] The gNB 200 (transmitter 210) sends downlink signaling to the NCR-MT 520A. The downlink signaling may be an RRC message as RRC layer (i.e., layer 3) signaling. The downlink signaling may be a MAC control element (CE) as MAC layer (i.e., layer 2) signaling. The downlink signaling may be downlink control information (DCI) as PHY layer (i.e., layer 1) signaling. 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). When the NCR-MT 520A is a base station or part of a base station, the NCR-MT 520A may communicate with the gNB 200 through an Xn's AP (Xn-AP) as an inter-base station interface.

[0091] For example, the gNB 200 (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 radio connection with the gNB 200 (step S1A). The NCR control signal specifying the operating state of the NCR device 500A may be a MAC CE (i.e., MAC layer (layer 2) signaling) or a DCI (i.e., PHY layer (layer 1) signaling). However, the NCR control signal may be included in an RRC reconfiguration message, which is a UE-specific RRC message to be sent to the NCR-MT 520A. The downlink signaling may be a message of a layer higher than the RRC layer (e.g., NCR application). The downlink signaling may transmit a message of a layer higher than the RRC layer, which is encapsulated in a message of the RRC layer or a layer lower than the RRC layer. Note that the NCR-MT 520A (transmitter 522) may send a response message in the uplink to the downlink signaling from the gNB 200. The response message may be sent in response to the NCR device 500A completing the configuration specified in the downlink signaling or receiving the configuration. The NCR control signal may be referred to as side control information.

[0092] The NCR control signal may include frequency control information for specifying a center frequency of a radio signal (e.g., component carrier) that is a target to be relayed by the NCR-Fwd 510A. When the NCR control signal received from the gNB 200 includes the frequency control information, the NCR-MT 520A (controller 523) controls the NCR-Fwd 510A so that the NCR-Fwd 510A relays a radio signal having a center frequency indicated by the frequency control information as a target to be relayed (step S2A). The NCR control signal may include a plurality of pieces of frequency control information for specifying center frequencies that are different from each other. Since the NCR control signal includes the frequency control information, the gNB 200 can specify the center frequency of the radio signal that is a target to be relayed by the NCR-Fwd 510A via the NCR-MT 520A.

[0093] The NCR control signal may include mode control information for specifying an operation mode of the NCR-Fwd 510A. The mode control information may be associated with the frequency control information (center frequency). The operation mode may be any one of the following modes: a mode in which the NCR-Fwd 510A performs non-directional transmission and / or reception, a mode in which the NCR-Fwd 510A performs fixed directional transmission and / or reception, a mode in which the NCR-Fwd 510A performs transmission and / or reception with a variable directional beam, and a mode in which the NCR-Fwd 510A performs multiple-input multiple-output (MIMO) relay transmission. The operation mode may be any one of a beamforming mode (i.e., a mode that emphasizes improving a desired wave) or a zero steering mode (i.e., a mode that emphasizes suppressing interference waves). When the NCR control signal received from the gNB 200 includes the mode control information, the NCR-MT 520A (controller 523) controls the NCR-Fwd 510A so that the NCR-Fwd 510A operates in the operation mode indicated by the mode control information (step S2A). Since the NCR control signal includes the mode control information, the gNB 200 can specify the operation mode of the NCR-Fwd 510A via the NCR-MT 520A.

[0094] Here, the mode in which the NCR device 500A performs non-directional transmission and / or reception is a mode in which the NCR-Fwd 510A performs relaying in all directions, and may be referred to as an omnidirectional mode. The mode in which the NCR-Fwd 510A performs fixed directional transmission and / or reception may be a directional mode implemented by one directional antenna. The mode may be a beamforming mode implemented by applying fixed phase and amplitude control (antenna weight control) to multiple antennas. Any of these modes may be specified (configured) from the gNB 200 to the NCR-MT 520A. The mode in which the NCR-Fwd 510A performs transmission and / or reception with a variable directional beam may be a mode for performing analog beamforming. The mode may be a mode for performing digital beamforming. The mode may be a mode for performing hybrid beamforming. The mode may be a mode for forming an adaptive beam specific to the UE 100. Any of these modes may be specified (configured) from the gNB 200 to the NCR-MT 520A. Note that in an operation mode in which beamforming is performed, the following beam control information 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 for performing single-user (SU) spatial multiplexing. The mode may be a mode for performing multi-user (MU) spatial multiplexing. The mode may be a mode for performing transmission diversity. Any of these modes may be specified (configured) from the gNB 200 to the NCR-MT 520A. The operation mode may include a mode for turning on (activating) the relay transmission performed by the NCR-Fwd 510A and a mode for turning off (deactivating) the relay transmission performed by the NCR-Fwd 510A. Any of these modes may be specified (configured) from the gNB 200 to the NCR-MT 520A in an NCR control signal.

[0095] The NCR control signal may include beam control information for specifying a transmission direction, a transmission weight, or a beam pattern of the NCR-Fwd 510A to perform directional transmission. The beam control information may be associated with the frequency control information (center frequency). The beam control information may include a precoding matrix indicator (PMI). The beam control information may include beamforming angle information. When the NCR control signal received from the gNB 200 includes the beam control information, the NCR-MT 520A (controller 523) controls the NCR-Fwd 510A so that the NCR-Fwd 510A forms a transmission directivity (beam) indicated by the beam control information (step S2A). Since the NCR control signal includes the beam control information, the gNB 200 can control the transmission directivity of the NCR device 500A via the NCR-MT 520A.

[0096] The NCR control signal may include output control information for specifying the degree (amplification gain) or transmission power of the NCR-Fwd 510A to amplify the radio signal. The output control information may be information indicating the difference (i.e., relative value) between the current amplification gain or transmission power and the target amplification gain or transmission power. When the NCR control signal received from the gNB 200 includes the output control information, the NCR-MT 520A (controller 523) controls the NCR-Fwd 510A so that the amplification gain or transmission power is changed to the amplification gain or transmission power indicated by the output control information (step S2A). The output control information may be associated with the frequency control information (center frequency). The output control information may be information for specifying any one of the amplification gain, beamforming gain, and antenna gain of the NCR-Fwd 510A. The output control information may be information for specifying the transmission power of the NCR-Fwd 510A.

[0097] When one NCR-MT 520A controls a plurality of NCR-Fwd 510A, the gNB 200 (transmitter 210) may transmit an NCR control signal for each NCR-Fwd 510A to the NCR-MT 520A. 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) controlling the plurality of NCR-Fwd 510A determines, based on the NCR identifier included in the received NCR control signal, the NCR-Fwd 510A to which the NCR control signal received from the gNB 200 is to be applied. Note that even in the case where the NCR-MT 520A controls only one NCR-Fwd 510A, the NCR identifier may be transmitted from the NCR-MT 520A to the gNB 200 together with the NCR control signal.

[0098] As described above, the NCR-MT 520A (controller 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.

[0099] (1.6) Example of uplink signaling

[0100] Fig.11 is a diagram showing an example of uplink signaling from NCR-MT 520A to gNB 200 according to the first embodiment.

[0101] NCR-MT 520A (transmitter 210) transmits uplink signaling to gNB 200. The uplink signaling may be an RRC message as RRC layer signaling. The uplink signaling may be a MAC CE as MAC layer signaling. The uplink signaling may be uplink control information (UCI) as PHY layer signaling. 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 transmit a message of a layer higher than the RRC layer, which is encapsulated in a message of the RRC layer or a layer lower than the RRC layer. That is, the uplink signaling stores a high-layer message in a low-layer container. Note that gNB 200 (transmitter 210) can send a response message to the uplink signaling from NCR-MT 520A in the downlink, and NCR-MT 520A (receiver 521) can receive the response message.

[0102] For example, NCR-MT 520A (transmitter 522) having established a radio connection with gNB 200 transmits NCR capability information indicating the capability of NCR device 500A to gNB 200 as uplink signaling (step S5A). NCR-MT 520A (transmitter 522) may include the NCR capability information in a UE capability message or a UE assistance information message, which is a type of RRC message to be transmitted to gNB 200. NCR-MT 520A (transmitter 522) may transmit the NCR capability information (NCR capability information and / or operation status information) to gNB 200 in response to a request or inquiry from gNB 200.

[0103] The NCR capability information may include supported frequency information indicating frequencies supported by the NCR-Fwd 510A. The supported frequency information may be a numerical value or an index indicating a center frequency of the frequencies supported by the NCR-Fwd 510A. The supported frequency information may be a numerical value or an index indicating a range of frequencies supported by the NCR-Fwd 510A. When the NCR capability information received from the NCR-MT 520A includes the supported frequency information, the gNB 200 (controller 230) may identify the frequencies supported by the NCR-Fwd 510A based on the supported frequency information. The gNB 200 (controller 230) may configure a center frequency of a radio signal as a target to be relayed by the NCR device 500A within the range of frequencies supported by the NCR-Fwd 510A.

[0104] The NCR capability information may include mode capability information related to the operation mode that the NCR-Fwd 510A can support or the switching between these operation modes. As described above, the operation mode may be at least any one of the modes selected from the group consisting of the following modes: a mode in which the NCR-Fwd 510A performs non-directional transmission and / or reception, a mode in which the NCR-Fwd 510A performs fixed directional transmission and / or reception, a mode in which the NCR-Fwd 510A performs transmission and / or reception with a variable directional beam, and a mode in which the NCR-Fwd 510A performs multiple-input multiple-output (MIMO) relay transmission. The operation mode may be any one of a beamforming mode (i.e., a mode that emphasizes improving the desired wave) or a zero steering mode (i.e., a mode that emphasizes suppressing interference waves). The mode capability information may be information indicating which operation mode among these operation modes the NCR-Fwd 510A can support. The mode capability information may be information indicating which operation modes among these operation modes can be switched in mode. When the NCR capability information received from the NCR-MT 520A includes the mode capability information, the gNB 200 (controller 230) may identify the operation mode and mode switching supported by the NCR-Fwd 510A based on the mode capability information. The gNB 200 (controller 230) may configure the operation mode of the NCR-Fwd 510A within the range of the identified operation mode and mode switching.

[0105] The NCR capability information may include beam capability information indicating a beam variable range, a beam variable resolution, or the number of variable patterns when the NCR-Fwd 510A performs transmission and / or reception with a variable directional beam. The beam capability information may be, for example, information indicating a variable range of a beam angle relative to a horizontal direction or a 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 represented by the direction and / or elevation angle to which the beam is pointed. The beam capability information may be information indicating an angle change for each 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 and 20 steps vertically). The beam capability information may be information indicating the number of variable patterns of the beam in the NCR-Fwd 510A (e.g., a total of 10 patterns of beam patterns 1 to 10). When the NCR capability information received from the NCR-MT 520A includes beam capability information, the gNB 200 (controller 230) may identify the beam angle variation or beam pattern that the NCR-Fwd 510A can support based on the beam capability information. The gNB 200 (controller 230) may configure the beam of the NCR-Fwd 510A within the range of the identified beam angle variation or beam pattern. The beam capability information may be zero capability information. For the zero capability information, the beam capability information indicates zero control capability when performing zero steering.

[0106] The NCR capability information may include control delay information indicating a control delay time in the NCR device 500A. For example, the control delay information is information indicating a delay time (e.g., 1 ms, 10 ms, ...) from the moment when the UE 100 receives the NCR control signal or the moment when the UE 100 sends the configuration completion for the NCR control signal to the gNB 200 to the moment when the UE 100 completes the control (changes the operation mode or changes the beam) according to the NCR control signal. When the NCR capability information received from the NCR-MT 520A includes the control delay information, the gNB 200 (controller 230) may identify the control delay time in the NCR-Fwd 510A based on the control delay information.

[0107] The NCR capability information may include amplification characteristic information related to radio signal amplification characteristics or output power characteristics in the NCR-Fwd 510A. The amplification characteristic information may be information indicating an amplifier gain (dB), a beamforming gain (dB), and an antenna gain (dBi) of the NCR-Fwd 510A. The amplification characteristic information may be information indicating an amplification variable range (e.g., 0 dB to 60 dB) in the NCR-Fwd 510A. The amplification characteristic information may be information indicating the number of steps (e.g., 10 steps) of the amplification degree that the NCR-Fwd 510A can change or the amplification degree of each variable step (e.g., 10 dB / step). The amplification characteristic information may be information indicating an output power variable range (e.g., 0 dBm to 30 dBm) of the NCR-Fwd 510A. The amplification characteristic information may be information indicating the number of steps (eg, 10 steps) of output power that the NCR-Fwd 510A can change or the output power per variable step (eg, 10 dBm / step or 10 dB / step).

[0108] The NCR capability information may include location information indicating the installation location of the NCR device 500A. The location information may include any 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 relative to the gNB 200. The installation angle may be a relative angle relative to the gNB 200 or a relative angle relative to, for example, north, vertical, or horizontal. The installation location may be location information of a location where the antenna 511a of the NCR-Fwd 510A is installed.

[0109] The NCR capability information may include antenna information indicating the number of antennas included in the NCR-Fwd 510A. The antenna information may be information indicating the number of antenna ports included in the NCR-Fwd 510A. The antenna information may be information indicating the degree of freedom of directivity control (beam or zero forming). The degree of freedom indicates how many beams can be formed (controlled), and is generally "(the number of antennas) - 1". For example, in the case of two antennas, the degree of freedom is 1. In the case of two antennas, an 8-shaped beam pattern is formed, but directivity control can be performed only in one direction, so the degree of freedom is 1.

[0110] When the NCR-MT 520A controls a plurality of NCR-Fwds 510A, the NCR-MT 520A (transmitter 522) may transmit NCR capability information of each NCR-Fwd 510A to the gNB 200. In this case, the NCR capability information may include the number of NCR-Fwds 510A and / or an identifier (NCR identifier) ​​of the corresponding NCR-Fwd 510A. When the NCR-MT 520A controls a plurality of NCR-Fwds 510A, the NCR-MT 520A (transmitter 522) may transmit information indicating the corresponding identifiers of the plurality of NCR-Fwds 510A and / or the number of the plurality of NCR-Fwds 510A. Note that even in the case where the NCR-MT 520A controls only one NCR-Fwd 510A, the NCR identifier may be transmitted from the NCR-MT 520A to the gNB 200 together with the NCR capability information.

[0111] (1.7) Examples of general operation sequences

[0112] Fig.12 1 is a diagram showing an example of a general operation sequence of the mobile communication system 1 according to the first embodiment. In the sequence diagrams mentioned in the following embodiments, dotted lines indicate non-essential steps. Note that although a detailed description will be given below, Fig.12 The "NCR" in can be interpreted as "RIS".

[0113] In step S11, the gNB 200 (transmitter 210) broadcasts NCR support information, which indicates that the gNB 200 supports the NCR-MT 520A. For example, the gNB 200 (transmitter 210) broadcasts a system information block (SIB) including the NCR support information. The NCR support information may be information indicating that the NCR-MT 520A is accessible. The gNB 200 (transmitter 210) may broadcast NCR non-support information, which indicates that the gNB 200 does not support the NCR-MT 520A. The NCR non-support information may be information indicating that the NCR-MT 520A is not accessible.

[0114] In this stage, NCR-MT 520A may be in an RRC idle state or an RRC inactive state. NCR-MT 520A (controller 523) that has not yet established a radio connection with gNB 200 may determine that it is allowed to access gNB 200 in response to receiving NCR support information from gNB 200, and may perform an access operation to establish a radio connection with gNB 200. NCR-MT 520A (controller 523) may regard the gNB 200 (cell) allowed to access as the highest priority and perform cell reselection.

[0115] On the other hand, when the gNB 200 does not broadcast the NCR support information (or when the gNB 200 broadcasts the NCR non-support information), the NCR-MT 520A (controller 523) that has not yet established a radio connection with the gNB 200 may determine that the gNB 200 cannot be accessed (cannot be connected to the gNB 200). This enables the NCR-MT 520A to establish a radio connection only with the gNB 200 that can handle the NCR-MT 520A.

[0116] Note that when the gNB 200 is congested, the gNB 200 may broadcast access restriction information to restrict access from the UE 100. However, unlike the normal UE 100, the NCR-MT 520A may be regarded as a network-side entity. Therefore, the NCR-MT 520A may ignore the access restriction information from the gNB 200. For example, the NCR-MT 520A (controller 523), upon receiving the NCR support information from the gNB 200, may perform an operation of establishing a radio connection with the gNB 200 even if the gNB 200 broadcasts the access restriction information. For example, the NCR-MT 520A (controller 523) may not need to perform (or may ignore) unified access control (UAC). Alternatively, either or both of the access category / access identity (AC / AI) used in the UAC may be a special value indicating that the access is made by the NCR-MT.

[0117] In step S12, NCR-MT 520A (controller 523) initiates a random access procedure for gNB 200. In the random access procedure, NCR-MT 520A (transmitter 522) sends a random access preamble (Msg1) and an RRC message (Msg3) to gNB 200. In the random access procedure, NCR-MT 520A (receiver 521) receives a random access response (Msg2) and an RRC message (Msg4) from gNB 200.

[0118] In step S13, when establishing a radio connection with the gNB 200, the NCR-MT 520A (transmitter 522) may transmit NCR-MT information to the gNB 200, which indicates that the NCR-MT 520A itself is the NCR-MT. For example, the NCR-MT 520A (transmitter 522) includes the NCR-MT information in a message (e.g., Msg1, Msg3, Msg5) for the random access procedure to be transmitted to the gNB 200 during the random access procedure with the gNB 200. The gNB 200 (controller 230) recognizes that the accessing UE 100 is the NCR-MT 520A based on the NCR-MT information received from the NCR-MT 520A. The gNB 200 (controller 230) may exclude, for example, the NCR-MT 520A from the access restriction target (in other words, accept access from, for example, the NCR-MT 520A). When 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.

[0119] In step S14, gNB 200 (transmitter 522) sends a capability query message to NCR-MT 520A to query the capability of NCR-MT 520A. NCR-MT 520A (receiver 521) receives the capability query message.

[0120] In step S15, NCR-MT 520A (transmitter 522) sends a capability information message including NCR capability information to gNB 200. The capability information message may be an RRC message, such as a UE capability message. gNB 200 (receiver 220) receives the capability information message. gNB 200 (controller 230) identifies the capability of NCR device 500A based on the received capability information message.

[0121] In step S16, gNB 200 (transmitter 522) sends a configuration message including various configurations about NCR device 500A to NCR-MT 520A. NCR-MT 520A (receiver 521) receives the configuration message. The configuration message is a kind of downlink signaling as described above. The configuration message may be an RRC message, such as an RRC reconfiguration message.

[0122] In step S17, gNB 200 (transmitter 522) sends a control indication to NCR-MT 520A specifying the operating state of NCR-Fwd 510A. The control indication may be the above-mentioned NCR control signal (e.g., L1 / L2 signaling). NCR-MT 520A (receiver 521) receives the control indication. NCR-MT 520A (controller 523) controls NCR-Fwd 510A in response to the control indication.

[0123] In step S18, the NCR-MT 520A controls the NCR device 500A according to the configuration (and the control instructions). The NCR-MT 520A may autonomously control the NCR device 500A without relying on the 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.

[0124] (1.8) Beam scanning

[0125] Fig.13 is a diagram for describing beam scanning according to an embodiment.

[0126] The gNB 200 performs beam scanning, in which transmission is performed while sequentially switching beams in different directions. At this time, the gNB 200 transmits a different SSB for each beam. The SSB is periodically transmitted from the gNB 200 to the cell as an SSB burst including a plurality of SSBs. In one SSB burst, an SSB index as an identifier is assigned to each of the plurality of SSBs. The SSBs are beamformed and transmitted in different directions. The NCR device 500A (NCR-MT 520A) reports to the gNB 200 in which direction the beam has good reception quality during the random access channel (RACH) procedure. Specifically, the NCR device 500A (NCR-MT 520A) transmits a random access preamble to the gNB 200 at a random access channel (RACH) opportunity associated with the SSB index of the beam having good reception quality. Therefore, the gNB 200 can identify the best beam of the NCR device 500A (NCR-MT520A).

[0127] 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 for the NCR device 500A (NCR-MT 520A). In a dedicated BWP, a channel state information reference signal (CSI-RS) may be used as a reference signal instead of an SSB. In the following, assuming that a beam and an SSB (specifically, an SSB index) have a one-to-one relationship, an example in which the beam information used to identify a beam is an SSB index will be mainly described. However, a beam may be associated with a CSI-RS. The beam information used to identify a beam may be a CSI-RS index.

[0128] (1.9) Carrier aggregation and dual connectivity

[0129] As described in the following embodiments, in an embodiment, the gNB 200 may configure multiple serving cells for the NCR device 500A (NCR-MT 520A) through carrier aggregation or dual connectivity (DC). Before describing such an operation, general CA and DC will be described.

[0130] Fig.14 is a diagram for describing CA. In CA, multiple component carriers (CCs) corresponding to multiple serving cells are aggregated so that the UE 100 can receive or transmit through multiple CCs at the same time. The multiple CCs may be continuous in the frequency direction. The multiple CCs may be non-contiguous.

[0131] When CA is configured, the UE 100 has only one RRC connection with the network (e.g., gNB 200). For RRC connection establishment / reestablishment / handover, one serving cell provides NAS mobility information, and for RRC connection reestablishment / handover, one serving cell provides security input. This one serving cell is called a primary cell (PCell). A group of serving cells can be formed by configuring a secondary cell (SCell) and a PCell together for the UE 100. Therefore, the group of serving cells configured for the UE 100 always includes one PCell and one or more SCells. SCells can be reconfigured, added, and deleted through RRC. Note that the primary cell is an MCG cell operating at the primary frequency where the UE 100 performs an initial connection establishment procedure or initiates a connection reestablishment procedure. When the UE 100 receives an RRCSetup message from a cell during the initial connection establishment procedure, the UE 100 regards the cell as the primary cell.

[0132] Fig.15 is a diagram for describing DC. According to DC, UE 100 simultaneously performs communication with a main 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. MN 200M and 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. Note that MN 200M may be referred to as a main base station, and SN 200S may be referred to as a secondary base station. In the description of the following embodiments, an example in which each of MN 200M and SN 200S is a gNB 200 is described, but MN 200M and / or SN 200S may also be an LTE base station (eNB).

[0133] For example, MN 200M sends a predetermined message (e.g., SN add request message) to SN 200S, and MN 200M sends an RRC reconfiguration message to UE 100 to start DC. In DC, schedulers of MN 200M and SN 200S allocate radio resources to UE 100 in an RRC connected state to perform wireless communication using the radio resources of MN 200M and the radio resources of SN 200S.

[0134] MN 200M may have a control plane connection with the core network. MN 200M provides primary radio resources for UE 100. MN 200M manages MCG 201M. MCG 201M is a set of service cells associated with MN 200M. MCG 201M includes a primary cell (PCell) and optionally one or more secondary cells (SCells). SN 200S may not need to have a control plane connection with the core network. SN 200S provides additional radio resources to UE 100. SN 200S manages SCG 201S. SCG201S includes a primary secondary cell (PSCell) and optionally one or more SCells. Note that the PCell of MCG 201M and the PSCell of SCG 201S may be referred to as a special cell (SPCell).

[0135] (1.10) Operation of a relay device using multiple serving cells

[0136] The operation of the relay device (NCR device 500A) using a plurality of serving cells will be described. Fig.16 is a diagram showing a configuration example when CA is configured for the NCR device 500A (NCR-MT 520A).

[0137] In an embodiment, the frequency of the control link (i.e., the radio link between the NCR-MT 520A and the gNB 200) is the same as the frequency of the backhaul link (i.e., the radio link between the NCR-Fwd 510A and the gNB 200). This frequency is also referred to as a "predetermined frequency". This allows alignment of channel states in the control link and the backhaul link to achieve simplification of control of the NCR-Fwd 510A. For example, based on channel state information (CSI) feedback sent from the NCR-Fwd 510A to the gNB 200, the gNB 200 can identify the channel state of the backhaul link and perform appropriate beamforming and link adaptation (e.g., determination of MCS) on the backhaul link.

[0138] Therefore, when a plurality of service cells are configured for the NCR device 500A (NCR-MT 520A), the gNB 200 configures the cell C2 corresponding to the frequency of the radio signal (from another perspective, component carrier) relayed by the NCR-Fwd 510A for the NCR device 500A (NCR-MT 520A). These frequencies are also referred to as "operating frequencies of the NCR-Fwd 510A". The service cell C2 is used for a control link and a backhaul link. The NCR-MT 520A communicates with the gNB 200 in Layer 1 and / or Layer 2 (L1 / L2) via a control link.

[0139] Here, the frequency of the service cell C2 may be a frequency in a millimeter wave band (also referred to as "FR (frequency range) 2"). In such a high frequency band, it is difficult to achieve stable wireless communication. Therefore, in an embodiment, by configuring the NCR device 500A (NCR-MT 520A) with a service cell C1 corresponding to a frequency different from that of the service cell C2, a connection of an RRC belonging to Layer 3 (L3) may be provided at a different frequency. Thus, the control link and the RRC connection may be separated. The frequency of the service cell C1 may be lower than that of the service cell C2, and may be, for example, a frequency in a sub-6 frequency band (also referred to as "FR1"). In an embodiment, the service cell C1 is a primary cell and the service cell C2 is a secondary cell. This may stabilize the RRC connection of the NCR-MT 520A and achieve simplification of control of the NCR-Fwd 510A.

[0140] Fig.17 is a diagram showing a configuration example when DC is configured for the NCR device 500A (NCR-MT 520A).

[0141] For DC, a service cell C1 is provided for the MN (gNB) 200M, and a service cell C2 is provided for the SN (gNB) 200S. For example, the service cell C1 is a primary cell of the MCG 201M belonging to the MN 200M. The service cell C2 is a secondary cell of the SCG 201S belonging to the SN 200S.

[0142] In this way, in an embodiment, the NCR-Fwd 510A relays a radio signal having 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 a plurality of service cells for the NCR-MT 520A, including a cell C1 corresponding to a predetermined frequency. This allows alignment of channel states in a control link and a backhaul link to achieve simplification of control of the NCR-Fwd 510A. In an embodiment, the cell C2 corresponding to the predetermined frequency is a secondary cell. Note that the secondary cell may be a primary secondary cell (PSCell) in DC.

[0143] The secondary cell may be inactive (i.e., not used for communication) when configured. The NCR-MT 520A configured with the secondary cell may receive an activation indication for activating the secondary cell from the gNB 200. The NCR-MT 520A may activate the operation of the NCR-Fwd 510A in response to receiving the activation indication, i.e., make the NCR-Fwd 510A available for relaying. Therefore, when the secondary cell is inactive, the operation of the NCR-Fwd 510A may also be inactive, so that power consumption and unexpected interference due to the NCR-Fwd 510A may be prevented.

[0144] The NCR-MT 520A may receive a deactivation indication for deactivating the secondary cell from the gNB 200. The NCR-MT 520A may deactivate the operation of the NCR-Fwd 510A in response to receiving the activation indication.

[0145] For DC, the MN 200M may send information related to the NCR device 500A to the SN 200S through a network interface (inter-base station interface). For example, the MN 200M may send information indicating the SCG addition of the NCR device 500A to the SN 200S when the SN is added. The MN 200M may send the cell ID associated with the NCR-Fwd 510A (i.e., the cell identifier of the cell C2) to the SN 200S. This makes it easy to implement Fig.17 The operation shown.

[0146] In this embodiment, the primary cell is used for the RRC connection between the gNB 200 and the NCR-MT 520A. The secondary cell is used for the control link between the gNB 200 and the NCR-MT 520A. Therefore, the frequency between the control link and the RRC connection can be different (that is, the control link and the RRC connection can be separated).

[0147] 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. Thus, for example, even if the NCR device 500A includes a plurality of NCR-Fwds 510A, the NCR-Fwd 510A to be associated with the secondary cell may be explicitly specified.

[0148] The NCR-MT 520A may receive a control signal (i.e., the above-mentioned NCR control signal) for controlling the NCR-Fwd 510A from the gNB 200 via a control link. The NCR control signal may include identification information for identifying the NCR-Fwd 510A. Thus, for example, even if the NCR device 500A includes a plurality of NCR-Fwds 510A, the NCR-Fwd 510A to be controlled may be explicitly specified.

[0149] (1.10.1) First operation example of a relay device using multiple serving cells

[0150] Fig.18 is a diagram showing a first operation example in which a plurality of serving cells are used for the NCR device 500A through CA.

[0151] In step S101, NCR-MT 520A establishes an RRC connection with gNB 200 and enters an RRC connected state. The primary cell (serving cell C1) of gNB 200 is allocated to NCR-MT 520A. Note that NCR-MT 520A may send the above-mentioned NCR capability information to gNB 200. The NCR capability information may include information indicating support for the control of the secondary cell over NCR-Fwd 510A.

[0152] In step S102, the gNB 200 performs CA configuration on the NCR-MT 520A. For example, the gNB 200 sends an RRC message (e.g., an RRC reconfiguration message) including CA configuration information to the NCR-MT 520A through the primary cell (serving cell C1). The NCR-MT 520A receives the CA configuration information. The CA configuration information includes information for associating 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 a list of at least one set of identifiers of the secondary cell (serving cell C2) and the identifier of the NCR-Fwd 510A. The CA configuration information may include information indicating in which secondary cell (serving cell C2) the NCR-MT 520A is controlled (i.e., a control link is established).

[0153] In step S103, gNB 200 sends an activation indication of the secondary cell to NCR-MT 520A. For example, gNB 200 sends a MAC CE including an activation indication to NCR-MT 520A through the primary cell (serving cell C1). NCR-MT 520A receives the activation indication. The activation indication may include an identifier of the secondary cell to be activated.

[0154] In step S104, the NCR-MT 520A activates the secondary cell (serving cell C2) configured in step S102 in response to receiving the activation indication. The NCR-MT 520A may also activate the NCR-Fwd 510A. Once the secondary cell (serving cell C2) is activated, the NCR-MT 520A starts beam selection and CSI feedback in the secondary cell (serving cell C2). Note that the activation indication of the secondary cell and the activation indication of the NCR-Fwd 510A may be different signaling. In this case, the NCR-MT 520A may activate the secondary cell upon receiving the activation indication of the secondary cell, and may activate the NCR-Fwd 510A upon receiving the activation indication of the NCR-Fwd 510A.

[0155] In step S105, the gNB 200 sends an NCR control signal (L1 / L2 signal) to the NCR-MT 520A in the secondary cell (serving cell C2) through a control link. 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.

[0156] In step S106, the NCR-MT 520A controls the NCR-Fwd 510A according to the NCR control signal received in step S105.

[0157] Then, in step S107, gNB 200 sends a deactivation indication of the secondary cell to NCR-MT 520A. For example, gNB 200 sends a MAC CE including a deactivation indication to NCR-MT 520A through the primary cell (serving cell C1) or the secondary cell (serving cell C2). NCR-MT 520A receives the deactivation indication. The deactivation indication may include an identifier of the secondary cell to be deactivated.

[0158] In step S108, the NCR-MT 520A deactivates the secondary cell (serving cell C2) activated in step S104 in response to receiving the deactivation indication. The NCR-MT 520A may deactivate the NCR-Fwd 510A. Once the secondary cell (serving cell C2) is deactivated, the NCR-MT 520A ends the beam selection and CSI feedback in the secondary cell (serving cell C2). Note that the deactivation indication of the secondary cell and the deactivation indication of the NCR-Fwd 510A may be different signaling. In this case, the NCR-MT 520A may deactivate the secondary cell upon receiving the deactivation indication of the secondary cell, and may deactivate the NCR-Fwd 510A upon receiving the deactivation indication of the NCR-Fwd 510A.

[0159] Fig.19 1 is a diagram showing a first operation example in which a plurality of serving cells are used for the NCR device 500A through DC. A repeated description of operations that are the same as and / or similar to those of the above-described CA will be omitted.

[0160] In step S201, NCR-MT 520A establishes an RRC connection with MN 200M (gNB 200) and enters an RRC connected state. The primary cell (serving cell C1) of MN 200M is allocated to NCR-MT 520A. Note that NCR-MT 520A may send the above-mentioned NCR capability information to gNB 200. The NCR capability information may include information indicating support for control of the secondary cell over NCR-Fwd 510A. Prior to step S202, SN 200S may send an SN addition request message to MN 200M to request the need for SN addition. The message may include information indicating a request to add NCR. MN 200M may perform step S202 in response to receiving the message.

[0161] In step S202, the MN 200M sends an SN add request message to the SN 200S through the inter-base station interface. The SN 200S receives the SN add request message. The SN add request message may include information indicating the SCG addition for controlling the NCR device 500A. The SN add request message may include information for associating the NCR-Fwd 510A with the secondary cell. For example, the SN add request message may include a list including an identifier of the NCR-Fwd 510A, an identifier of the NCR device 500A, and / or an identifier of the NCR-MT 520A and at least one set of cell IDs. The SN add request message may include a list including an identifier of the NCR-Fwd 510A, an identifier of the NCR device 500A, and / or an identifier of the NCR-MT 520A and at least one set of frequency identifiers.

[0162] In step S203, the SN 200S sends an SN add request response message to the MN 200M through the inter-base station interface, and the SN add request response message includes the RRC reconfiguration (RRC container) to be sent to the NCR-MT 520A. The MN 200M receives the SN add request response message. The RRC reconfiguration (RRC container) includes DC configuration information. The DC configuration information includes information for associating the secondary cell (serving cell C2) configured for the NCR-MT 520A with the NCR-Fwd 510A. For example, the DC configuration information may include a list of at least one set of identifiers of the secondary cell (serving cell C2) and the identifier of the NCR-Fwd 510A. The DC configuration information may include information indicating in which secondary cell (serving cell C2) the NCR-MT 520A is controlled (i.e., a control link is established). The DC configuration information may include information indicating the operating frequency of the NCR-Fwd 510A.

[0163] In step S204, the MN 200M sends the RRC reconfiguration (DC configuration information) included in the SN add request response message received in step S203 to the NCR-MT 520A.

[0164] The operations in steps S205 to S210 are the same as Fig.18 The operations in steps S103 to S108 of are the same and / or similar. However, the activation indication / deactivation indication of the secondary cell can be sent from the SN 200S to the NCR-MT 520A. Note that before step S205 or S209, the SN 200S can send a message to the MN 200M requesting activation or deactivation of the NCR. The MN 200M can perform steps S205 or S209 in response to receiving the message. The SN 200S can request the MN 200M to remove the NCR configuration. Upon receiving the request, the MN 200M can send an SN removal request message to the SN 200S. The message can be a message for removing the configuration of the NCR device 500A. For example, the message can be a message for removing the configuration of the NCR-Fwd 510A.

[0165] (1.10.2) Second operation example of a relay device using multiple serving cells

[0166] This operation example is an operation example related to the deactivation timer of the secondary cell (also referred to as "sCellDeactivationTimer"). sCellDeactivationTimer is a timer that the gNB 200 configures for the UE 100 in association with the secondary cell. sCellDeactivationTimer is a timer for deactivating the secondary cell in response to a situation where there is no data communication in the secondary cell for a period of time of a predetermined period, and is used to measure the predetermined period. This allows the unused secondary cell to be spontaneously deactivated.

[0167] Fig. 20 is a diagram used to describe sCellDeactivationTimer. Fig. 20 In the specification, "A" to "C" indicate the description contents of the 3GPP technical specification "TS 38.321" (i.e., MAC protocol specification), and Fig. 20 The “D” in indicates the description content of the 3GPP technical specification “TS 38.331” (ie, RRC protocol specification).

[0168] like Fig. 20 As shown in "A" in FIG. 1 , the UE 100 configured with the sCellDeactivationTimer deactivates the secondary cell (SCell) associated with the sCellDeactivationTimer in response to the expiration of the sCellDeactivationTimer. Note that the sCellDeactivationTimer may be configured separately for each secondary cell (SCell).

[0169] like Fig. 20 As shown in “B” in FIG. 1 , the UE 100 configured with the sCellDeactivationTimer starts or restarts the sCellDeactivationTimer in response to a secondary cell (SCell) associated with the sCellDeactivationTimer being activated.

[0170] like Fig. 20As shown in "C" in FIG. 1 , the UE 100 configured with the sCellDeactivationTimer restarts the sCellDeactivationTimer in response to receiving a DCI for resource allocation (more specifically, a DL assignment or UL grant on the PDCCH of the secondary cell (SCell) associated with the sCellDeactivationTimer or the PDCCH of the serving cell scheduling the secondary cell (SCell). The UE 100 restarts the sCellDeactivationTimer in response to receiving or sending data (MAC PDU) on the downlink or uplink resources pre-allocated by the configured grant.

[0171] like Fig. 20 As shown in “D” in FIG. 1 , when the sCellDeactivationTimer is not configured for the secondary cell, the UE 100 uses infinity as the timer value of the sCellDeactivationTimer of the secondary cell.

[0172] Assumptions Fig. 20 In the operation of the NCR-MT 520A, when the NCR-MT 520A is controlled in the secondary cell (serving cell C2), that is, when the control link for the NCR-MT 520A is provided in the secondary cell (serving cell C2), the following problem occurs. More specifically, configuring the sCellDeactivationTimer for the secondary cell (serving cell C2) may cause the secondary cell (serving cell C2) to be deactivated when the sCellDeactivationTimer expires. For example, when the NCR control signal received through the control link is a MAC CE, or when the NCR control signal received through the control link is a non-scheduled DCI, it is considered that the NCR-MT 520A does not restart the sCellDeactivationTimer in response to receiving the NCR control signal. Therefore, the secondary cell (serving cell C2) may be disadvantageously deactivated, thereby interrupting the control of the NCR device 500A (NCR-MT 520A).

[0173] To this end, the gNB 200 that configures the secondary cell (serving cell C2) associated with the NCR-Fwd 510A for the NCR-MT 520A does not configure the sCellDeactivationTimer for the secondary cell. That is, the gNB 200 avoids configuring the SCell deactivation timer for the secondary cell that forms the control link of the NCR-Fwd 510A (configuration of the sCellDeactivationTimer for the secondary cell is not allowed). Therefore, the NCR-MT 520A applies an infinite value as the timer value of the sCellDeactivationTimer, thereby preventing the secondary cell (serving cell C2) from being deactivated due to the sCellDeactivationTimer.

[0174] When the secondary cell forming the control link of NCR-Fwd 510A is configured with sCellDeactivationTimer, NCR-MT 520A may ignore the timer value of sCellDeactivationTimer (ie, the configured sCellDeactivationTimer) and use an infinite value as the timer value of sCellDeactivationTimer. This may prevent the secondary cell (serving cell C2) from being deactivated due to sCellDeactivationTimer.

[0175] (1.10.3) Third Operation Example of Relay Device Using Multiple Serving Cells

[0176] This operation example is a variation of the second operation example described above. In this operation example, NCR-MT 520A restarts sCellDeactivationTimer in response to receiving an NCR control signal for controlling NCR-Fwd 510A from gNB 200 via the control link of the secondary cell (serving cell C2). This can prevent the secondary cell (serving cell C2) from being deactivated due to sCellDeactivationTimer.

[0177] Fig.21 1 and 2 are diagrams showing this operation example. A repeated description of operations that are the same as and / or similar to those in the above-described first and second operation examples will be omitted.

[0178] In step S301, NCR-MT 520A establishes an RRC connection with gNB 200 and enters an RRC connected state. The primary cell (serving cell C1) of MN 200M is allocated to NCR-MT 520A.

[0179] In step S302, the gNB 200 performs CA configuration or DC configuration on the NCR-MT 520A. Here, the gNB 200 configures the secondary cell (serving cell C2) for controlling the NCR-Fwd 510A for the NCR-MT 520A. The configuration includes a configuration timer value of the sCellDeactivationTimer. The configuration may include information for specifying whether to restart the sCellDeactivationTimer when an NCR control signal (L1 / L2 signal) (specifically, DCI for NCR control) is received. The information may include the cell ID of the secondary cell (serving cell C2) and / or the identifier of the NCR-Fwd 510A.

[0180] In step S303, gNB 200 sends an activation indication of the secondary cell (serving cell C2) to NCR-MT 520A.

[0181] In step S304, the NCR-MT 520A (or the NCR device 500A) activates the secondary cell (serving cell C2) and the NCR-Fwd 510A in response to receiving the activation indication. The NCR-MT 520A starts the sCellDeactivationTimer configured for the secondary cell (serving cell C2) in step S302.

[0182] In step S306, gNB 200 sends an NCR control signal (L1 / L2 signal) to NCR-MT 520A in the secondary cell (serving cell C2) through the control link.

[0183] In step S307, the NCR-MT 520A controls the NCR-Fwd 510A according to the NCR control signal. In response to receiving the NCR control signal (L1 / L2 signal), the NCR-MT 520A restarts the sCellDeactivationTimer configured for the secondary cell (serving cell C2) in step S302.

[0184] Thereafter, when 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 deactivate the corresponding NCR-Fwd 510A.

[0185] (1.10.4) Fourth operation example of a relay device using multiple serving cells

[0186] In this operation example, NCR-MT 520A detects that a fault has occurred in the control link (i.e., the secondary cell). NCR-MT 520A sends information related to the detected fault to gNB 200 through the primary cell. This enables gNB 200 to recognize that a fault has occurred in the control link.

[0187] Fig. 22 1 to 3. The repeated description of the operations that are the same as and / or similar to those in the above-mentioned first to third operation examples will be omitted.

[0188] In step S401, the NCR-MT 520A establishes an RRC connection with the gNB 200 and enters an RRC connected state. The primary cell (serving cell C1) of the MN 200M is allocated to the NCR-MT 520A.

[0189] In step S402, gNB 200 performs CA configuration or DC configuration on NCR-MT 520A. The configuration may include configuration related to monitoring of the control link (e.g., a threshold value of the quality of the control link). Here, gNB 200 configures the secondary cell (serving cell C2) for controlling NCR-Fwd 510A for NCR-MT520A.

[0190] In step S403, the gNB 200 sends an activation indication of the secondary cell (serving cell C2) to the NCR-MT 520A. In response to receiving the activation indication, the NCR-MT 520A activates the secondary cell (serving cell C2) and the NCR-Fwd 510A.

[0191] In step S404, the NCR-MT 520A monitors the reception quality of the reference signal (SSB and / or CSI-RS) received through the control link. The NCR-MT 520A may perform the monitoring only when configured by the gNB 200. The reception quality may be RSRP / RSRQ / SINR of the control link.

[0192] In step S405, the NCR-MT 520A determines whether a failure in the control link is detected. The NCR-MT 520A may determine whether a failure corresponding to a radio link failure (RLF) has occurred in the control link. When the measured reception quality is lower than a threshold, the NCR-MT 520A may determine that a failure has occurred. The threshold may be configured from the gNB 200.

[0193] When it is determined that a failure in the control link is detected (step S405: Yes), in step S406, the NCR-MT 520A notifies the gNB 200 of the failure information of the control link through the primary cell. For example, the NCR-MT 520A sends 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 occurred, an identifier of the secondary cell, and / or information on the frequency at which the failure occurred.

[0194] (1.11) Relay device troubleshooting operations

[0195] The operation of the NCR device 500A performing fault processing according to the embodiment is described. In the following embodiments, it may not be necessary to configure multiple serving cells for the NCR device 500A. Multiple serving cells may be configured for the NCR device 500A.

[0196] The NCR-Fwd 510A relays radio signals transmitted and received between the gNB 200 and the UE 100 as described above. The NCR-MT 520A controls the NCR-Fwd 510A by performing wireless communication with the gNB 200 via a control link. Here, the NCR-MT 520A performs predetermined control corresponding to the failure in response to detecting a failure in the control link or the NCR-Fwd 510A. When a plurality of service cells are configured for the NCR device 500A as described above, the NCR-MT 520A may transmit failure information of the control link or failure information of the NCR-Fwd 510A to the gNB 200 through the primary cell.

[0197] (1.11.1) First operation example for troubleshooting

[0198] In this operation example, NCR-MT 520A detects that a fault has occurred in the control link. NCR-MT 520A stops the operation of NCR-Fwd 510A in response to the fault occurring in the control link. When a fault occurs in the control link, NCR-Fwd 510A operating in an uncontrolled state may cause problems such as interference. Therefore, stopping the operation of NCR-Fwd510A can prevent such problems from occurring. Note that NCR-MT 520A can detect that the fault in the control link has been resolved. NCR-MT 520A can send a notification to gNB 200 in response to the fault being resolved.

[0199] Fig.23 2 is a diagram showing an example of the operation. A repeated description of operations that are the same as and / or similar to those of the above-described embodiment will be omitted.

[0200] In step S501, NCR-MT 520A establishes an RRC connection with gNB 200 and enters the RRC connection state. gNB 200 may send an NCR control signal (L1 / L2 signal) to NCR-MT 520A via a control link. NCR-MT 520A controls NCR-Fwd 510A according to the NCR control signal.

[0201] In step S502, the NCR-MT 520A may monitor the reception quality of the reference signal (SSB and / or CSI-RS) received through the control link. The NCR-MT 520A may perform the monitoring only when configured by the gNB 200. The reception quality may be RSRP / RSRQ / SINR of the control link.

[0202] In step S503, the NCR-MT 520A determines whether a failure in the control link is detected. The NCR-MT 520A may determine whether a failure corresponding to a radio link failure (RLF) has occurred in the control link. When the measured reception quality is lower than a threshold, the NCR-MT 520A may determine that a failure has occurred. The threshold may be configured from the gNB 200.

[0203] For example, NCR-MT 520A may determine that a failure in the control link is detected when any of the following events occurs:

[0204] - A fault corresponding to RLF occurs in the control link;

[0205] -RLF occurs in the primary cell;

[0206] - Start RRC re-establishment;

[0207] - Sending MCG failure information related to the failure of the MCG to the gNB 200;

[0208] - Sending SCG failure information related to the failure of the SCG to the gNB 200;

[0209] - Transition to RRC Idle state or RRC Inactive state (e.g. RRC reestablishment fails); and

[0210] -Connect to a cell different from the current serving cell.

[0211] When it is determined that a failure in the control link is detected (step S503 : Yes), in step S504 , the NCR-MT 520A (or the NCR device 500A) stops the operation of the NCR-Fwd 510A (ie, the relay operation of the radio signal).

[0212] Then, in step S505 , NCR-MT 520A may determine whether the failure in the control link has been resolved (returned to normal).

[0213] When it is determined that the failure in the control link has been resolved (step S505: Yes), in step S506, NCR-MT520A may send a notification to gNB200 indicating that the operation of NCR-Fwd510A is being stopped. gNB200 may perform configuration and control on NCR device 500A again in response to receiving the notification. gNB200 may control NCR device 500A to restore the previous configuration and control state (i.e., reactivate NCR-Fwd510A).

[0214] (1.11.2) Second operation example for troubleshooting

[0215] In this operation example, gNB 200 configures the content of predetermined control for NCR-Fwd 510A (i.e., control when a failure occurs) for NCR-MT 520A. NCR-MT 520A detects that a failure has occurred in the control link. NCR-MT 520A performs control of the content configured by gNB 200 for NCR-Fwd 510A in response to the failure occurring in the control link.

[0216] For example, when the gNB 200 configures the NCR device 500A to periodically perform a predetermined operation, there may be a control method for continuing the operation of the NCR-Fwd 510A even if a failure occurs in the control link. Therefore, the gNB 200 may configure the NCR-Fwd 510A whether to continue the operation of the NCR-MT 520A when a failure occurs in the control link.

[0217] Fig.24 2 is a diagram showing an example of the operation. A repeated description of operations that are the same as and / or similar to those of the above-described embodiment will be omitted.

[0218] In step S601, NCR-MT 520A establishes an RRC connection with gNB 200 and enters the RRC connected state.

[0219] In step S602, the gNB 200 sends configuration information to the NCR-MT 520A, the configuration information indicating the content of control of the NCR-Fwd 510A when a failure occurs in the control link. The gNB 200 may send an RRC message (e.g., an RRC reconfiguration message) including the configuration information to the NCR-MT 520A. The NCR-MT 520A receives the configuration information. The gNB 200 may send an NCR control signal (L1 / L2 signal) to the NCR-MT 520A through the control link. The NCR-MT 520A controls the NCR-Fwd 510A according to the NCR control signal.

[0220] The configuration information in step S602 may include information for designating any one of stopping the operation of the NCR-Fwd 510A, canceling the configuration of the NCR-Fwd 510A, and continuing the operation of the NCR-Fwd 510A as the content of control when a failure occurs in the control link. When continuing the operation of the NCR-Fwd 510A, the configuration information may include an NCR control signal indicating a beamforming method when a failure occurs in the control link, etc.

[0221] In step S603 , the NCR-MT 520A may monitor the reception quality of the reference signals (SSB and / or CSI-RS) received through the control link.

[0222] In step S604, NCR-MT 520A determines whether a failure in the control link is detected according to the above method.

[0223] When it is determined that a failure in the control link is detected (step S604: Yes), in step S605, the NCR-MT 520A performs the control configured 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 according to the contents that have been configured and controlled. The NCR-MT 520A may continue the operation of the NCR-Fwd 510A according to the NCR control signal configured in step S602.

[0224] The operations in steps S606 to S607 are the same as or similar to those in the above-mentioned embodiment.

[0225] (1.11.3) Example of the third operation for troubleshooting

[0226] In this operation example, NCR-MT 520A detects that a fault has occurred in NCR-Fwd 510A (eg, NCR-Fwd 510A fails). NCR-MT 520A sends fault information of NCR-Fwd 510A to gNB 200 in response to the fault occurring in NCR-Fwd 510A.

[0227] Fig.25 2 is a diagram showing an example of the operation. A repeated description of operations that are the same as and / or similar to those of the above-described embodiment will be omitted.

[0228] In step S701, NCR-MT 520A establishes an RRC connection with gNB 200 and enters an RRC connection state. gNB 200 may perform configuration related to monitoring NCR-Fwd 510A for NCR-MT 520A. gNB 200 may send an NCR control signal (L1 / L2 signal) to NCR-MT 520A via a control link. NCR-MT 520A controls NCR-Fwd 510A according to the NCR control signal.

[0229] 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 selected from the group consisting of a load state, a control delay time (control response time), and a heating value of the NCR-Fwd 510A.

[0230] In step S703, NCR-MT 520A determines whether a fault in NCR-Fwd 510A is detected. For example, NCR-MT 520A may determine that a fault in the control link is detected when any of the following events occurs:

[0231] -Fault in NCR-Fwd 510A;

[0232] -NCR-Fwd 510A processing has not yet caught up with the configuration and control from gNB 200, e.g., NCR-Fwd 510A control cannot be performed in response to NCR control signals from gNB 200;

[0233] - The load (e.g., usage of hardware resources) on the NCR-Fwd 510A has exceeded a threshold. Note that this threshold may be configured from the gNB 200;

[0234] - a failure has occurred in the control link; and

[0235] - Incorrect control values ​​are received in the NCR control signals (L1 / L2 signals) and / or RRC reconfiguration messages from the gNB 200, which may correspond to, for example, receiving control values ​​(weights, etc.) that are not supported by the NCR-Fwd 510A.

[0236] When it is determined that a fault in NCR-Fwd 510A is detected (step S703: Yes), in step S704, NCR-MT 520A sends fault information related to the detected fault to gNB 200. gNB 200 requires the fault information. For example, NCR-MT 520A may send an RRC message including the fault information to gNB 200, for example, a message such as NCR Fault Information or a UE Assistance Information message.

[0237] The configuration message may include at least one selected from the group consisting of the following information elements:

[0238] - an information element indicating a fault in NCR-Fwd 510A;

[0239] - an information element indicating a processing delay, load increase or overheating of the NCR-Fwd 510A;

[0240] - an information element indicating a failure in the control link;

[0241] - may include a desired configuration and control value of the NCR-Fwd 510A, for example, a preferred value of an upper limit of the number of antennas and / or an upper limit of a frequency bandwidth to be controlled, and the gNB 200 may change the configuration and control for the NCR device 500A according to the desired configuration and control value; and

[0242] - Identifier of NCR-Fwd 510A when a fault has occurred.

[0243] The gNB 200 that receives the fault information in step S704 may send information to the NCR-MT 520A for specifying any one of stopping the operation of the NCR-Fwd 510A, canceling the configuration of the NCR-Fwd 510A, and continuing the operation of the NCR-Fwd 510A as the content of control in the fault handling.

[0244] Then, in step S705 , the NCR-MT 520A may determine whether the failure in the NCR-Fwd 510A has been resolved (returned to normal).

[0245] When it is determined that the fault in NCR-Fwd 510A has been resolved (step S705: Yes), in step S706, NCR-MT 520A may send a notification indicating that the fault in NCR-Fwd 510A has been resolved to gNB 200. The notification may include an identifier of NCR-Fwd 510A whose fault has been resolved.

[0246] (2) Second Embodiment

[0247] Regarding the second embodiment, the differences from the above-mentioned first embodiment are mainly described. The overview of the mobile communication system 1 and the configuration of the gNB 200 according to the second embodiment are the same and / or similar to the overview of the mobile communication system 1 and the configuration of the gNB 200 of the above-mentioned first embodiment.

[0248] like Fig.26 As shown, the relay device according to the second embodiment is a reconfigurable smart surface (RIS) device 500B configured to change the propagation direction of incident radio waves (radio signals) by reflection or refraction. The "NCR" in the above-mentioned first and second embodiments can be interpreted as "RIS".

[0249] RIS is a repeater (hereinafter, also referred to as "RIS-Fwd") that can perform beamforming (directivity control) in the same and / or similar manner as NCR by changing the characteristics of metamaterials. RIS can change the range (distance) of a beam by controlling the reflection direction and / or refraction direction of each unit element. For example, RIS can have a configuration that can control the reflection direction and / or refraction direction of each unit element and focus on a near UE (steering beam) or focus on a far UE (steering beam).

[0250] The RIS device 500B includes 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 controls the RIS-Fwd 510B in cooperation with the gNB 200 by establishing a radio connection with the gNB 200 and performing wireless communication with the gNB 200. The RIS-Fwd 510B may be a reflective RIS. Such a RIS-Fwd 510B reflects incident radio waves to change the propagation direction of the radio waves. Here, the reflection angle of the radio signal may be variably configured. The RIS-Fwd 510B reflects the radio waves incident from the gNB 200 toward the UE 100. The RIS-Fwd 510B may be a transmissive RIS. Such a RIS-Fwd 510B refracts the incident radio waves to change the propagation direction of the radio waves. Here, the refraction angle of the radio signal may be variably configured.

[0251] Fig. 27 5 is a diagram showing a configuration example of a RIS-Fwd (repeater) 510B and a RIS-MT (control terminal) 520B according to a second embodiment. RIS-MT 520B includes a receiver 521, a transmitter 522, and a controller 523. This configuration is the same and / or similar to the configuration in the first embodiment described above. RIS-Fwd 510B includes RIS 511B and a RIS controller 512B. RIS511B is a metasurface configured using a metamaterial. For example, RIS 511B is configured by arranging very small structures in an array form with respect to the wavelength of a radio signal, wherein the direction and beam shape of a reflected wave can be arbitrarily designed by forming structures of different shapes depending on the arrangement position. RIS 511B can be a transparent dynamic metasurface. RIS 511B can be configured to include a transparent glass substrate stacked on a metasurface substrate, on which a large number of tiny structures are regularly arranged and made transparent, and RIS 511B can dynamically control the following three modes by slightly moving the stacked glass substrate: a mode of transmitting an incident radio signal, a mode of transmitting a portion of the radio signal and reflecting a portion of the radio signal, and a mode of reflecting all radio signals. RIS controller 512B controls RIS 511B according to a RIS control signal from a controller 523 in RIS-MT 520B. RIS controller 512B may include at least one processor and at least one actuator. The processor interprets the RIS control signal from the controller 523 in RIS-MT 520B to drive the actuator according to the RIS control signal.

[0252] (3) Another embodiment

[0253] In the above-mentioned 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 the configuration from the gNB 200. Fig.28 is a diagram showing an example of beam scanning according to another embodiment. For the backhaul link, the gNB 200 transmits multiple beams (beams of SSB3 to SSB5 in the example shown) with the same transmission weight in the direction of the NCR device 500A. For the access link, the NCR device 500A (NCR-Fwd 510A) autonomously transmits multiple beams (beams of SSB3 to SSB5) with different transmission weights in different directions. Under this assumption, when a failure occurs, the NCR device 500A (NCR-MT 520A) can autonomously control the NCR-Fwd 510A based on the configuration from the gNB 200.

[0254] The above operation flow can be implemented separately and independently, and can also be implemented in combination of two or more operation flows. For example, some steps in one operation flow can be added to another operation flow, or some steps in one operation flow can be replaced by some steps in another operation flow. In each flow, not all steps need to be executed, but only some steps can be executed.

[0255] In the above embodiment, an example in which the base station is an NR base station (i.e., gNB) is described; however, the base station may also be an LTE base station (i.e., eNB). The base station may be a relay node, such as an integrated access and backhaul (IAB) node. The base station may be a distributed unit (DU) of an IAB node.

[0256] A program that causes a computer to perform each process performed by UE 100 (NCR-MT 520A, RIS-MT 520B) or gNB 200 may be provided. The program may be recorded on a computer-readable medium. The use of a computer-readable medium enables the program to 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 specifically limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. A circuit for performing a process to be performed by UE 100 or gNB 200 may be integrated, and at least a portion of UE 100 or gNB 200 may be implemented as a semiconductor integrated circuit (chip set, system on chip (SoC)).

[0257] Unless otherwise expressly stated, the phrases "based on" and "depending on / in response to" used in this disclosure do not mean "based only on" and "depending only on / in response to". The phrase "based on" means both "based only on" and "based at least in part on". The phrase "depending on" means both "depending only on" and "depending at least in part on". The terms "include", "include" and their variations do not mean "only including the items", but mean "may only include the items" or "may include not only the items but also other items". The term "or" used in this disclosure is not intended to be an "exclusive or". In addition, any reference to elements using names such as "first" and "second" in this disclosure does not generally limit the number or order of these elements. These names can be used as a convenient method to distinguish two or more elements in this article. Therefore, the reference to the first element and the second element does not mean that only two elements can be used there or that the first element needs to be in some way before the second element. For example, when English articles such as "one", "an" and "the" are added in this disclosure by translation, these articles include plural unless otherwise clearly indicated in the context.

[0258] The embodiments have been described in detail above with reference to the accompanying drawings, but the specific configuration is not limited to the above configuration, and various design changes may be made without departing from the gist of the present disclosure.

[0259] This application claims priority from Japanese Patent Application No. 2021-126137 (filed on August 8, 2022), the entire contents of which are incorporated herein by reference.

[0260] (4) Supplementary notes

[0261] Features related to the above-described embodiment are described below as supplements.

[0262] Supplementary Note 1

[0263] A communication method using a relay device in a mobile communication system, comprising:

[0264] The relay included in the relay device relays a radio signal transmitted between the base station and the user equipment;

[0265] A control terminal included in the relay device performs control of the relay by performing wireless communication with the base station via a control link;

[0266] The control terminal detects that a fault has occurred in the control link or repeater; and

[0267] In response to the failure, the control terminal performs predetermined control.

[0268] Supplementary Note 2

[0269] The communication method according to Supplementary Note 1, wherein:

[0270] Detection includes: detecting that a fault has occurred in the control link, and

[0271] The performing of the predetermined control includes stopping the operation of the repeater in response to the occurrence of a failure of the control link.

[0272] Supplementary Note 3

[0273] The communication method according to Supplementary Note 1 or 2, further comprising:

[0274] The base station configures the repeater's predetermined control content for the control terminal,

[0275] The detection includes: detecting that a fault has occurred in the control link, and

[0276] The performing of the predetermined control includes: performing control of the contents configured by the base station for the repeater in response to the failure of the control link.

[0277] Supplementary Note 4

[0278] The communication method according to Supplementary Note 3, wherein:

[0279] The content of configuring the predetermined control for the control terminal includes: configuring whether to make the repeater continue to operate when a failure has occurred in the control link.

[0280] Supplementary Note 5

[0281] The communication method according to any one of Supplementary Notes 1 to 4, wherein:

[0282] The detection includes: detecting that a fault has occurred in the repeater,

[0283] The performing of the predetermined control includes: sending failure information of the repeater to the base station in response to the repeater failing.

[0284] Supplementary Note 6

[0285] The communication method according to any one of Supplementary Notes 1 to 5, further comprising:

[0286] detecting that the fault has been resolved; and

[0287] A notification is sent to the base station in response to resolving the fault.

[0288] Supplementary Note 7

[0289] A relay device used in a mobile communication system, the relay device comprising:

[0290] a repeater configured to relay a radio signal transmitted between the base station and the user equipment; and

[0291] a control terminal configured to control the repeater by performing wireless communication with the base station via a control link,

[0292] When it is detected that a fault has occurred in the control link or the repeater, the control terminal performs predetermined control in response to the fault.

[0293] Reference numerals

[0294] 1: Mobile communication system

[0295] 100: UE

[0296] 200: gNB

[0297] 210: Transmitter

[0298] 220: Receiver

[0299] 230: Controller

[0300] 240: Backhaul Communicator

[0301] 500A: NCR device

[0302] 500B:RIS device

[0303] 511A: Radio Unit

[0304] 511a: Antenna

[0305] 511b: RF circuit

[0306] 511c: Directional Controller

[0307] 512A: NCR controller

[0308] 512B:RIS controller

[0309] 521: Receiver

[0310] 522: Transmitter

[0311] 523: Controller

[0312] 530: Interface

Claims

1. A communication method using a relay device in a mobile communication system, the communication method comprising: The relay device includes a relay that relays a radio signal sent between a base station and a user equipment; The control terminal included in the relay device performs control of the relay by performing wireless communication with the base station via a control link; The control terminal detects a fault that has occurred in the control link; as well as After the control terminal detects a failure in the control link, the repeater ceases operation.

2. The communication method according to claim 1, further comprising: The base station configures the predetermined control content of the repeater for the control terminal, The detection includes: detecting that a fault has occurred in the control link, The performing of the predetermined control includes: performing control of the contents configured by the base station for the repeater in response to the occurrence of the failure in the control link.

3. The communication method according to claim 2, wherein: Configuring the predetermined control content for the control terminal includes: configuring whether to enable the repeater to continue operating when a failure has occurred in the control link.

4. The communication method according to claim 1, wherein: The detection includes: detecting that a fault has occurred in the repeater, The performing of the predetermined control includes: sending failure information of the repeater to the base station in response to the failure occurring in the repeater.

5. The communication method according to any one of claims 1 to 4, further comprising: detecting that the fault has been resolved; as well as A notification is sent to the base station in response to resolving the fault.

6. A relay device used in a mobile communication system, the relay device comprising: a repeater configured to relay a radio signal transmitted between the base station and the user equipment; as well as a control terminal configured to control the repeater by performing wireless communication with the base station via a control link, Wherein, the repeater is configured to include ceasing operation after the control terminal detects that a failure has occurred in the control link.

7. The communication method according to claim 1, comprising: In response to detecting a failure in the control link, the control terminal initiates RRC reestablishment, The stopping includes: stopping the operation of the relay in response to starting the RRC reconstruction.

8. The communication method according to claim 1, further comprising: In response to detecting a failure in the control link, the control terminal initiating RRC reestablishment; as well as When the RRC reestablishment fails, the control terminal switches to the RRC idle state, The stopping includes: stopping the operation of the relay in response to transitioning to the RRC idle state.

9. A communication method using a relay device in a mobile communication system, the communication method comprising: The relay device includes a relay that relays a radio signal sent between a base station and a user equipment; The control terminal included in the relay device performs control of the relay by performing wireless communication with the base station via a control link; The control terminal switches to an RRC inactive state; as well as After the control terminal switches to the RRC inactive state, the relay continues to operate according to the configuration content that has been received from the base station.

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