Communication method and relay device

Abstract

Provided is a communication method executed by a relay device which has a relay that performs a relay operation for relaying a wireless signal which is transmitted between a network and a user device and a control terminal that receives, from the network, a control signal which is used for control of the relay, said communication method comprising: a step for measuring a wireless environment which is related to the relay device; and a step for transmitting, from the control terminal to the network, measurement information which has been obtained by the measurement.

Description

Communication method and relay device

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

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

[0003] Wireless signals (radio waves) in high frequency bands such as millimeter waves or terahertz waves have a tendency to propagate in a highly directional manner, which can lead to a reduction in the coverage area of ​​base stations. To solve this problem, a repeater device, which is a type of relay device that relays wireless signals between a network and a user device and can be controlled from a network, has attracted attention (see, for example, Non-Patent Document 1).

[0004] Such a repeater device can, for example, amplify a radio signal received from a base station and transmit the signal using directional transmission, thereby expanding the coverage of the base station while suppressing interference. Note that such a repeater device is also called an NCR (Network-Controlled Repeater) device.

[0005] 3GPP contribution: RP-213700, “New SI: Study on NR Network-controlled Repeaters”

[0006] A communication method according to a first aspect is a communication method executed by a relay device having a relay device that performs relaying operations to relay radio signals transmitted between a network and a user device, and a control terminal that receives control signals from the network used to control the relay device, and includes the steps of measuring the radio environment related to the relay device, and transmitting measurement information obtained by the measurement from the control terminal to the network.

[0007] A relay device according to a second aspect is a relay device comprising a repeater that performs relaying operations to relay radio signals transmitted between a network and a user device, and a control terminal that receives control signals from the network to be used to control the repeater, wherein the control terminal measures the radio environment related to the relay device and transmits measurement information obtained by the measurement from the control terminal to the network.

[0008] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. FIG. 1 is a diagram illustrating a configuration of a protocol stack of a radio interface of a user plane that handles data. FIG. 2 is a diagram illustrating a configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals). FIG. 2 is a diagram illustrating an example of an application scenario of an NCR device (relay device) according to the first embodiment. FIG. 3 is a diagram illustrating an example of an application scenario of an NCR device according to the first embodiment. FIG. 4 is a diagram illustrating an example of a control method of an NCR device according to the first embodiment. FIG. 5 is a diagram illustrating an example of a configuration of a protocol stack in an NCR device according to the first embodiment. FIG. 6 is a diagram illustrating an example of an operation of a mobile communication system according to the first embodiment. FIG. 7 is a diagram illustrating an example of a configuration of an NCR device according to the first embodiment. FIG. 8 is a diagram illustrating a configuration of a UE (user equipment) according to an embodiment. FIG. 9 is a diagram illustrating an example of a configuration of a gNB (base station) according to an embodiment. FIG. 10 is a diagram illustrating an operation of an NCR device according to the first embodiment. FIG. 11 is a diagram illustrating a first operation pattern according to the first embodiment. FIG. 12 is a diagram illustrating a second operation pattern according to the first embodiment. FIG. 13 is a diagram illustrating an operation scenario according to a third operation pattern according to the first embodiment. FIG. 14 is a diagram illustrating an example of an application scenario of a RIS device (relay device) according to the second embodiment. FIG. 15 is a diagram illustrating an example of a configuration of a RIS device according to the second embodiment.

[0009] By having the network autonomously adjust the configuration parameters for the relay devices described above or autonomously change the operation of the relay devices, it is possible to optimize the network and increase the effectiveness of introducing relay devices.

[0010] Therefore, an object of the present disclosure is to facilitate the realization of network optimization.

[0011] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

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

[0013] (1.1) Overview of the Mobile Communication System FIG. 1 is a diagram showing the configuration of a mobile communication system according to the first embodiment.

[0014] The mobile communication system 1 conforms to the 5th Generation System (5GS) standard of the 3rd Generation Partnership Project (3GPP) (registered trademark; the same applies hereinafter). While the following description will be given using 5GS as an example, the mobile communication system may also be at least partially based on the Long Term Evolution (LTE) system. The mobile communication system may also be at least partially based on the 6th Generation (6G) system.

[0015] The mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN: Next Generation Radio Access Network) 10, and a 5G core network (5GC: 5G Core Network) 20. Hereinafter, the NG-RAN 10 may be simply referred to as the RAN 10. Furthermore, the 5GC 20 may be simply referred to as the core network (CN) 20. The RAN 10 and the CN 20 constitute a network 5 of the mobile communication system 1.

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

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

[0018] The gNB200 may be functionally divided into a central unit (CU) and a distributed unit (DU). The CU controls the DU. The CU is a unit including upper layers included in the protocol stack described below, such as an RRC layer, an SDAP layer, and a PDCP layer. The CU is connected to the core network via an NG interface, which is a backhaul interface. The CU is connected to neighboring base stations via an Xn interface, which is an interface between base stations. The DU forms a cell. The DU202 is a unit including lower layers included in the protocol stack described below, such as an RLC layer, a MAC layer, and a PHY layer. The DU is connected to the CU via an F1 interface, which is a fronthaul interface.

[0019] In addition, gNBs can also be connected to the Evolved Packet Core (EPC), which is the core network of LTE. LTE base stations can also be connected to 5GC. LTE base stations and gNBs can also be connected via an inter-base station interface.

[0020] The 5GC20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF controls data forwarding. The AMF and the UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0021] FIG. 2 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0022] The user plane radio interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0023] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of gNB200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from gNB200 on a physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires successfully decoded DCI as DCI addressed to the UE. The DCI transmitted from gNB200 has CRC bits scrambled by the RNTI added.

[0024] In addition, the gNB 200 transmits a synchronization signal block (SSB: Synchronization Signal / PBCH block). For example, the SSB is composed of four consecutive OFDM (Orthogonal Frequency Division Multiplex) symbols, and includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH) / master information block (MIB), and a PBCH demodulation reference signal (DMRS). The bandwidth of the SSB is, for example, 240 consecutive subcarriers, that is, a bandwidth of 20 RBs.

[0025] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the gNB 200 via a transport channel. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE 100.

[0026] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 via a logical channel.

[0027] The PDCP layer performs header compression / decompression, encryption / decryption, and the like.

[0028] The SDAP layer maps IP flows, which are units for Quality of Service (QoS) control by the core network, to radio bearers, which are units for QoS control by the Access Stratum (AS). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0029] FIG. 3 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals).

[0030] The protocol stack of the radio interface of the control plane has an RRC (Radio Resource Control) layer and an NAS (Non-Access Stratum) layer instead of the SDAP layer shown in FIG.

[0031] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in an RRC inactive state.

[0032] The NAS layer, which is located above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the AMF 300A. Note that the UE 100 has an application layer and the like in addition to the radio interface protocol. Also, a layer lower than the NAS layer is called an AS (Access Stratum).

[0033] (1.2) Example of Application Scenarios of Relay Devices FIGS. 4 and 5 are diagrams showing examples of application scenarios of the NCR device according to the first embodiment.

[0034] Compared to 4G / LTE, 5G / NR enables broadband transmission using higher frequency bands. Radio signals in high frequency bands, such as the millimeter wave band or terahertz wave band, have high line-of-sight properties, which poses a challenge in reducing the coverage of the gNB 200. In FIG. 4, the UE 100 may be located outside the coverage area of ​​the gNB 200, for example, outside an area where radio signals can be received directly from the gNB 200. A shield may exist between the gNB 200 and the UE 100, preventing the UE 100 from communicating with the gNB 200 within line-of-sight.

[0035] As shown in Figure 4, a repeater device (500A), which is a type of relay device that relays radio signals between the gNB 200 and the UE 100, and an NCR device 500A that can be controlled from the network 5 is introduced into the mobile communication system 1. Such a repeater device may be referred to as a smart repeater device.

[0036] For example, the NCR device 500A amplifies a radio signal (radio wave) received from the gNB 200 and transmits it by directional transmission. Specifically, the NCR device 500A receives a radio signal transmitted by the gNB 200 by beamforming. The NCR device 500A then amplifies the received radio signal without demodulating or modulating it, and transmits the amplified radio signal by directional transmission. Here, the NCR device 500A may transmit a radio signal with a fixed directivity (beam). The NCR device 500A may also transmit a radio signal with a variable (adaptive) directional beam. This allows the coverage of the gNB 200 to be efficiently expanded.

[0037] Also, as shown in FIG. 5, a new UE (hereinafter referred to as "NCR-MT (Mobile termination)") 100B, which is a type of control terminal for controlling the NCR device 500A, is introduced. That is, the NCR device 500A relays radio signals transmitted between the gNB 200 and the UE 100, specifically, the radio signals. NCR-Fwd (Forward) 510A, which is a type of repeater that changes the propagation state of the radio signal without demodulating or modulating the radio signal, and NCR-MT 520A that performs wireless communication with the gNB 200 and controls the NCR-Fwd 510A.

[0038] In this way, the NCR-MT 520A establishes a wireless connection with the gNB 200 and performs wireless communication with the gNB 200, thereby controlling the NCR device 500A in cooperation with the gNB 200. This enables efficient coverage expansion using the NCR device 500A. The NCR-MT 520A controls the NCR device 500A according to control from the gNB 200. The NCR-MT 520A also has functions similar to those of the UE 100.

[0039] The NCR-MT 520A may be configured separately from the NCR-Fwd 510A. For example, the NCR-MT 520A may be located near the NCR-Fwd 510A and electrically connected to the NCR-Fwd 510A. The NCR-MT 520A may be connected to the NCR-Fwd 510A by wire or wirelessly. Alternatively, the NCR-MT 520A may be configured integrally with the NCR-Fwd 510A. The NCR-MT 520A and the NCR-Fwd 510A may be fixedly installed, for example, at the coverage edge (cell edge) of the gNB 200 or on a wall or window of a building. The NCR-MT 520A and the NCR-Fwd 510A may be installed, for example, in a vehicle or the like and be mobile. Also, one NCR-MT 520A may control multiple NCR-Fwds 510A.

[0040] Note that the configuration is not limited to one in which the NCR-MT 520A directly controls one or more NCR-Fwds 510A, and may be one in which the NCR-MT 520A indirectly controls one or more NCR-Fwds 510A. For example, the NCR-MT 520A may control one or more NCR-Fwds 510A via a higher layer (for example, an application layer).

[0041] In the example shown in FIG. 5, the NCR device 500A (NCR-Fwd 510A) dynamically or quasi-statically changes the beam to be transmitted or received. For example, the NCR-Fwd 510A forms a beam toward each of the UE 100a and the UE 100b. The NCR-Fwd 510A may also form a beam toward the gNB 200. For example, in the communication resources between the gNB 200 and the UE 100a, the NCR-Fwd 510A transmits a radio signal received from the gNB 200 toward the UE 100a by beamforming, and / or transmits a radio signal received from the UE 100a toward the gNB 200 by beamforming. In the communication resources between the gNB 200 and the UE 100b, the NCR-Fwd 510A transmits a radio signal received from the gNB 200 toward the UE 100b by beamforming, and / or transmits a radio signal received from the UE 100b by beamforming toward the gNB 200. Instead of or in addition to beamforming, the NCR-Fwd 510A may form a null (so-called null steering) toward a UE 100 (not shown) and / or a neighboring gNB 200 (not shown) that is not a communication partner for interference suppression.

[0042] FIG. 6 is a diagram showing an example of a control method for the NCR device 500A according to the first embodiment.

[0043] The NCR-Fwd 510A relays radio signals (also referred to as "UE signals") between the gNB 200 and the UE 100. The UE signals include uplink signals (also referred to as "UE-UL signals") transmitted from the UE 100 to the gNB 200 and downlink signals (also referred to as "UE-DL signals") transmitted from the gNB 200 to the UE 100. The NCR-Fwd 510A relays UE-UL signals from the UE 100 to the gNB 200 and relays UE-DL signals from the gNB 200 to the UE 100. The radio link between the NCR-Fwd 510A and the UE 100 is also referred to as an "access link." The radio link between the NCR-Fwd 510A and the gNB 200 is also referred to as a "backhaul link."

[0044] The NCR-MT 520A transmits and receives radio signals (herein referred to as "NCR-MT signals") to and from the gNB 200. The NCR-MT signals include uplink signals (herein referred to as "NCR-MT-UL signals") transmitted from the NCR-MT 520A to the gNB 200, and downlink signals (herein referred to as "NCR-MT-DL signals") transmitted from the gNB 200 to the NCR-MT 520A. The NCR-MT-DL signals include signaling (e.g., NCR control signals) for controlling the NCR device 500A. The radio link between the NCR-MT 520A and the gNB 200 is also referred to as a "control link."

[0045] The gNB200 directs a beam to the NCR-MT520A based on the NCR-MT-UL signal from the NCR-MT520A. Because the NCR device 500A is co-located with the NCR-MT520A, if the backhaul link and the control link have the same frequency, when the gNB200 directs a beam to the NCR-MT520A, the beam will also be directed to the NCR-Fwd510A. The gNB200 uses this beam to transmit an NCR-MT-DL signal and a UE-DL signal. The NCR-MT520A receives the NCR-MT-DL signal. In addition, when the NCR-Fwd 510A and the NCR-MT 520A are at least partially integrated, the functions (e.g., antennas) for transmitting, receiving, or relaying UE signals and / or NCR-MT signals may be integrated in the NCR-Fwd 510A and the NCR-MT 520A. Note that the term "beam" includes a transmitting beam and / or a receiving beam. A beam is a general term for transmission and / or reception controlled to maximize the power of transmitted waves and / or received waves in a specific direction by adjusting / adapting antenna weights, etc.

[0046] FIG. 7 is a diagram for explaining an example of the configuration of a protocol stack in the NCR device 500A according to the first embodiment.

[0047] The NCR-Fwd 510A relays radio signals transmitted and received between the gNB 200 and the UE 100. The NCR-Fwd 510A has an RF (Radio Frequency) function that amplifies and relays received radio signals, and performs directional transmission using beamforming (e.g., analog beamforming).

[0048] The NCR-MT 520A has entities for each of the layers: Layer 1 and / or Layer 2 (L1 / L2), RRC, and NAS. The L1 / L2 (especially PHY and MAC) and RRC of the NCR-MT 520A are also referred to as the "AS of the NCR-MT 520A."

[0049] The NCR-MT 520A may have at least one of an OAM client that communicates with the OAM (Operation, Administration, Maintenance) server 400, a NAS layer that communicates with the AMF 300A, and an F1-AP (Application Protocol) layer. The OAM client, NAS layer, and F1-AP layer of the NCR-MT 520A are also referred to as the "upper layers of the NCR-MT 520A" based on the AS of the NCR-MT 520A.

[0050] A backhaul link is established between the gNB200 and the NCR-Fwd510A. An access link is established between the UE100 and the NCR-Fwd510A. The NCR-Fwd510A relays radio signals transmitted between the gNB200 and the UE100 via the backhaul link and the access link. The NCR-Fwd510A changes the propagation state of the radio signal without demodulating or modulating the radio signal.

[0051] In addition, a control link is established between gNB200 and L1 / L2 of NCR-MT520A. L1 / L2 of NCR-MT520A transmits and receives L1 / L2 signaling with gNB200 via the control link. An RRC connection is established between gNB200 and RRC of NCR-MT520A. RRC of NCR-MT520A transmits and receives RRC messages with gNB200 via the RRC connection. NCR-MT520A receives downlink signaling (also referred to as an "NCR control signal" or simply "control signal") from gNB200 via the RRC connection and / or the control link.

[0052] The gNB 200 (transmitter 210) transmits an NCR control signal to the NCR-MT 520A. The NCR control signal may be an RRC message, which is a control signal of the RRC layer (i.e., Layer 3). The NCR control signal may be a MAC Control Element (CE), which is a control signal of the MAC layer (i.e., Layer 2). The NCR control signal may be downlink control information (DCI), which is a control signal of the PHY layer (i.e., Layer 1). The NCR control signal may be UE-specific signaling. The NCR control signal may be broadcast signaling. The NCR control signal may be a fronthaul message (e.g., an F1-AP message). If the NCR-MT 520A is a type or part of a base station, the NCR-MT 520A may communicate with the gNB 200 via an Xn AP (Xn-AP), which is an inter-base station interface.

[0053] Hereinafter, an NCR control signal transmitted in an RRC message (and / or MAC CE) and used for static or semi-static control of the NCR-Fwd 510A will also be referred to as "NCR configuration information" or simply as "configuration information." Such configuration information may be referred to as "Side Control Configuration." Here, the RRC message may be an RRC Reconfiguration message. The NCR configuration information includes, for example, information for setting the NCR-Fwd 510A to on / off. The NCR configuration information may also include, for example, information for semi-static beam configuration of the NCR-Fwd 510A.

[0054] On the other hand, an NCR control signal transmitted in L1 / L2 signaling, i.e., DCI (and / or MAC CE), and used for dynamic control of the NCR-Fwd 510A is also referred to as "NCR control information" or simply "control information." The NCR control information may also be referred to as "side control information." The CRC (Cyclic Redundancy Code) bits of the PDCCH carrying the NCR control information are scrambled by a newly introduced dedicated RNTI. This dedicated RNTI is also referred to as "NCR-RNTI." The NCR control information may include, for example, information on dynamic beam control of the NCR-Fwd 510A. The NCR setting information may include information instructing dynamic on / off of the NCR-Fwd 510A.

[0055] For example, when the NCR-MT 520A is in the RRC connected state, the NCR device 500A can turn on or off the NCR-Fwd 510A according to the NCR control information received from the gNB 200. On the other hand, after the NCR-MT 520A transitions to the RRC inactive state, the NCR device 500A can turn on or off the NCR-Fwd 510A according to the latest (last) setting information received from the gNB 200.

[0056] In addition, the NCR control signal (e.g., NCR setting information by RRC and / or NCR control information by L1 / L2 signaling) held by the NCR device 500A (NCR-MT 520A) may be referred to as an NCR-Fwd context.

[0057] Also, if a radio link failure (RLF) with the gNB200 is detected by the NCR-MT520A, the NCR-MT520A performs cell selection and triggers RRC connection re-establishment (also referred to as "RRC re-establishment"). Here, if the NCR-MT520A enters an RRC idle state because a suitable cell cannot be found in the cell selection, the NCR device 500A turns off the NCR-Fwd510A. Note that the NCR-Fwd510A is off during the RRC connection re-establishment procedure.

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

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

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

[0061] The NCR control signal may include beam control information that specifies the transmission direction, transmission weight, or beam pattern when the NCR-Fwd 510A performs directional transmission. The beam control information may be associated with frequency control information (center frequency). The beam control information may include a PMI (Precoding Matrix Indicator). The beam control information may include beam formation angle information. When the NCR control signal received from the gNB 200 includes beam control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to form the transmission directivity (beam) indicated by the beam control information. By including beam control information in the NCR control signal, the gNB 200 can control the transmission directivity of the NCR device 500A via the NCR-MT 520A.

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

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

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

[0065] FIG. 8 is a diagram for explaining an example of the operation of the mobile communication system 1 according to the first embodiment.

[0066] As shown in STEP 1 of FIG. 8, the NCR device 500A is in an RRC connected state in cell a (first cell) of the gNB 200a. The gNB 200a transmits an RRC Reconfiguration message including an NCR setting to the NCR device 500A. The NCR device 500A receives the RRC Reconfiguration message including the NCR setting from the gNB 200a (cell a) and performs relay operation using the NCR setting. For example, the NCR setting includes a periodic beam indicator. In the periodic beam indicator, the period and beam are set by RRC. The NCR device 500A performs periodic beamforming based on the periodic beam indicator.

[0067] As shown in STEP 2 of FIG. 8, the gNB 200a transmits an RRC Release message including a suspend setting to the NCR device 500A. The NCR device 500A receives the RRC Release message from the gNB 200a (cell a) and transitions to the RRC inactive state. After transitioning to the RRC inactive state, the NCR-MT 520A controls the NCR-Fwd 510A according to the latest (last) NCR setting. For example, the NCR-MT 520A controls the NCR-Fwd 510A to continue periodic beamforming operation according to the NCR setting (latest setting) received in STEP 1.

[0068] In addition, the NCR-MT 520A in the RRC inactive state may perform cell reselection from cell a to cell b. In response to cell reselection to cell b, the NCR-MT 520A may turn off the NCR-Fwd 510A (i.e., stop the relay operation).

[0069] (1.3) Configuration Examples of Each Device A configuration example of each device in the mobile communication system 1 according to the first embodiment will be described.

[0070] 9 is a diagram showing an example of the configuration of an NCR device 500A according to the first embodiment. The NCR device 500A includes an NCR-Fwd 510A, an NCR-MT 520A, and an interface 530.

[0071] The NCR-Fwd 510A includes a radio unit 511A and an NCR control unit 512A. The radio unit 511A includes an antenna unit 511a including multiple antennas (multiple antenna elements), an RF circuit 511b including an amplifier, and a directivity control unit 511c that controls the directivity of the antenna unit 511a. The RF circuit 511b amplifies and relays (transmits) radio signals transmitted and received by the antenna unit 511a. The RF circuit 511b may convert analog radio signals into digital signals and then reconvert them to analog signals after digital signal processing. The directivity control unit 511c may perform analog beamforming using analog signal processing. The directivity control unit 511c may perform digital beamforming using digital signal processing. The directivity control unit 511c may perform hybrid analog and digital beamforming. The NCR control unit 512A controls the radio unit 511A in response to control signals from the NCR-MT 520A. The NCR control unit 512A may include at least one processor.

[0072] The NCR-Fwd 510A may have a measurement unit 511d that measures the wireless environment related to the NCR device 500A (NCR-Fwd 510A) and outputs the measurement results to the NCR control unit 512A. The NCR control unit 512A outputs the measurement results to the NCR-MT 520A (control unit 523) via the interface 530. In the illustrated example, the measurement unit 511d is provided in the wireless unit 511A of the NCR-Fwd 510A, but the measurement unit 511d may be provided outside the wireless unit 511A. The measurement unit 511d may also be provided in the NCR-MT 520A.

[0073] The measurement unit 511d may measure an uplink (UL) signal from the UE 100 to the NCR-Fwd 510A in the access link. The measurement unit 511d may perform digital detection (i.e., demodulation and measurement) of the UL signal and measure a specific band (for example, a specific physical resource block (PRB) and / or a specific subcarrier). The measurement unit 511d may be configured to include an analog detector instead of a digital detector and may perform only measurement of the entire band at once. The measurement unit 511d may measure the received power and / or received quality of the UL signal in the NCR-Fwd 510A. The received power of the UL signal may be the received power of an UL reference signal (RSRP: Reference Signal Received Power). The reception quality of the UL signal may be the reception quality of the UL reference signal (RSRQ: Reference Signal Received Quality) and / or SINR (Signal to Interference plus Noise Ratio). Note that the measurement unit 511d may be included in the NCR-MT 520A. In this case, the measurement unit 511d may output the measurement results to the control unit 523. Such a configuration is effective when the NCR-Fwd 510A and the NCR-MT 520A operate in the same band and / or when a circuit configuration is adopted that allows the components (e.g., RF circuit 511b) of the radio unit 511A of the NCR-Fwd 510A to be measured by the NCR-MT 520A.

[0074] The measurement unit 511d may measure a downlink (DL) signal from the NCR-Fwd 510A to the UE 100 in the access link. The measurement unit 511d may perform digital detection on the DL signal fed back from the transmitting end (antenna end) of the NCR-Fwd 510A and measure a specific band (for example, a specific physical resource block (PRB) and / or a specific subcarrier). The measurement unit 511d may be configured to include an analog detector instead of a digital detector and may perform only measurement of the entire band at once. The measurement unit 511d may measure the transmission power of the DL signal in the NCR-Fwd 510A, for example, the entire band power ([dBm]) or the partial band power ([dBm]). The measurement unit 511d may acquire the gain ([dB]) set in the NCR-Fwd 510A as a measured value. The measuring unit 511d may measure the gain of the NCR-Fwd 510A by having a wave detector at the receiving end (antenna end) of the NCR-Fwd 510A.

[0075] The measurement unit 511d may measure the UL signal from the NCR-Fwd 510A to the gNB 200 in the backhaul link. The measurement unit 511d may perform digital detection on the UL signal fed back from the transmitting end (antenna end) of the NCR-Fwd 510A and measure a specific band (for example, a specific physical resource block (PRB) and / or a specific subcarrier). The measurement unit 511d may be configured to include an analog detector instead of a digital detector, and may perform only measurements of the entire band at once. The measurement unit 511d may measure the transmission power of the UL signal in the NCR-Fwd 510A, for example, the entire band power ([dBm]) or the partial band power ([dBm]). The measurement unit 511d may acquire the gain ([dB]) set in the NCR-Fwd 510A as a measured value. The measuring unit 511d may measure the gain of the NCR-Fwd 510A by having a wave detector at the receiving end (antenna end) of the NCR-Fwd 510A.

[0076] The measurement unit 511d may measure DL signals from the gNB 200 to the NCR-Fwd 510A in the backhaul link. For measurements of DL signals from the gNB 200 to the NCR-Fwd 510A, the measurement unit 511d may be at least partially shared with the receiver 521 of the NCR-MT 520A. The measurement unit 511d may perform digital detection (i.e., demodulation and measurement) of the DL signal and measure a specific band (e.g., a specific physical resource block (PRB) and / or a specific subcarrier). The measurement unit 511d may be configured to include an analog detector instead of a digital detector, and may perform only measurements of the entire band at once. The measurement unit 511d may measure the received power and / or reception quality of the DL signal at the NCR-Fwd 510A. The received power of the DL signal may be the received power (RSRP) of a DL reference signal. The reception quality of the DL signal may be the reception quality of the DL reference signal (RSRQ) and / or the SINR.

[0077] The NCR-MT 520A has a receiving unit 521, a transmitting unit 522, and a control unit 523. The receiving unit 521 performs various receptions under the control of the control unit 523. The receiving unit 521 includes an antenna and a receiver. The receiver converts a radio signal (wireless signal) received by the antenna into a baseband signal (received signal) and outputs it to the control unit 523. The transmitting unit 522 performs various transmissions under the control of the control unit 523. The transmitting unit 522 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmitted signal) output by the control unit 523 into a radio signal and transmits it from the antenna. The control unit 523 performs various controls on the NCR-MT 520A. The operations of the NCR-MT 520A (and the NCR device 500A) described above and below may be operations controlled by the control unit 523. The control unit 523 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes. In addition, the control unit 523 executes the functions of at least one layer of PHY, MAC, RRC, and F1-AP.

[0078] The NCR-MT 520A may have a GNSS (Global Navigation Satellite System) receiver 524. The GNSS receiver 524 receives satellite signals from positioning satellites and outputs GNSS position information indicating the geographical position of the NCR device 500A (NCR-MT 520A) to the control unit 523. The GNSS position information includes at least one of latitude, longitude, and altitude. The GNSS receiver 524 may be provided in the NCR-Fwd 510A or the interface 530. If multiple NCR-Fwds 510A are present, the GNSS receiver 524 may be provided in each of the multiple NCR-Fwds 510A.

[0079] The interface 530 electrically or logically connects the NCR-Fwd 510A and the NCR-MT 520A. The control unit 523 of the NCR-MT 520A controls the NCR-Fwd 510A via the interface 530. The interface 530 may be a logical entity of an upper layer (e.g., an application layer).

[0080] In the first embodiment, the receiver 521 of the NCR-MT 520A receives signaling (NCR control signal) used to control the NCR device 500A from the gNB 200 via wireless communication. The controller 523 of the NCR-MT 520A controls the NCR device 500A based on the signaling. This enables the gNB 200 to control the NCR-Fwd 510A via the NCR-MT 520A.

[0081] (1.3.2) Example of configuration of user device Fig. 10 is a diagram showing the configuration of the UE 100 (user device) according to the first embodiment. The UE 100 has a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit that performs wireless communication with the gNB 200.

[0082] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

[0083] The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0084] The control unit 130 performs various controls and processes in the UE 100. Such processes include processes of each layer described below. The operations of the UE 100 described above and below may be operations controlled by the control unit 130. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0085] (1.3.3) Configuration example of base station Figure 11 is a diagram showing a configuration example of a gNB 200 (base station) according to the first embodiment. The gNB 200 has a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240.

[0086] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna. The receiving unit 220 performs various receptions under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (reception signal) and outputs it to the control unit 230. The transmitting unit 210 and the receiving unit 220 may be capable of beamforming using multiple antennas.

[0087] The control unit 230 performs various controls in the gNB 200. The operations of the gNB 200 described above and below may be operations controlled by the control unit 230. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0088] The backhaul communication unit 240 is connected to adjacent base stations via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF 300 via a base station-core network interface. The gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally divided), and the two units may be connected via an F1 interface.

[0089] In the first embodiment, the transmitter 210 of the gNB 200 transmits signaling (NCR control signal) used to control the NCR-Fwd 510A to the NCR-MT 520A via wireless communication. This enables the gNB 200 to control the NCR device 500A via the NCR-MT 520A.

[0090] (1.4) Operation According to the First Embodiment The NCR device 500A can expand the coverage of the gNB 200 while suppressing interference, for example, by amplifying a radio signal received from the gNB 200 and transmitting it using directional transmission. It is believed that network optimization becomes possible and the introduction effect of the NCR device 500A can be enhanced by the network autonomously adjusting the setting parameters related to the NCR device 500A or autonomously changing the operation of the NCR device 500A. In the first embodiment, an operation for facilitating the realization of network optimization will be described.

[0091] 12 is a diagram showing the operation of the NCR device 500A according to the first embodiment. As described above, the NCR device 500A includes an NCR-Fwd 510A that performs a relay operation to relay a wireless signal transmitted between the network 5 and the UE 100, and an NCR-MT 520A that receives a control signal used to control the NCR-Fwd 510A from the network 5.

[0092] In step S1, the NCR device 500A measures the radio environment related to the NCR device 500A.

[0093] In step S2, the NCR device 500A transmits the measurement information obtained by the measurement in step S1 from the NCR-MT 520A to the network 5.

[0094] This allows the network 5 to grasp the wireless environment related to the NCR device 500A based on the measurement information, making it easier to achieve network optimization.

[0095] In the first embodiment, step S1 may include a step of measuring the radio environment of the access link between the NCR device 500A and the UE 100. The radio environment of the access link is information that the gNB 200 does not know directly. The network 5 can grasp the radio environment of the access link based on the measurement information, which makes it easier to realize network optimization such as optimizing the access link.

[0096] In the first embodiment, the step of measuring the radio environment of the access link may include a step of measuring the reception power and / or reception quality of an UL radio signal received by the NCR device 500A from the UE 100. The step of measuring the radio environment of the access link may include a step of measuring the transmission power of a DL radio signal transmitted from the NCR device 500A to the UE 100. Step S1 may include a step of measuring the transmission power of an UL radio signal transmitted from the NCR device 500A to the network 5. Such an operation will be described in detail in the first operation pattern of the first embodiment described later.

[0097] In the first embodiment, step S1 may include a step of measuring and maintaining the radio environment in response to an off control being performed to switch the NCR-Fwd 510A from an on state to an off state. Such an operation will be described in detail in the second operation pattern of the first embodiment described later. Note that step S1 may include a step of measuring and maintaining the radio environment in response to any of the following events: 1) the occurrence of a beam failure; 2) the execution of beam recovery; or 3) the selection of a beam different from the current beam as a result of beam recovery. Step S1 may also include a step of measuring and maintaining the radio environment in response to the NCR-MT 520A transitioning to an RRC idle state or an RRC inactive state.

[0098] In the first embodiment, step S1 may include a step of measuring the state of the beam formed by the gNB 200. Such an operation will be described in detail in the third operation pattern of the first embodiment described later.

[0099] In the first embodiment, step S1 may include measuring the radio environment when the NCR-MT 520A is in an RRC connected state. Step S2 may include transmitting measurement information to the network 5 when the NCR-MT 520A is in an RRC connected state. This enables more real-time feedback.

[0100] In the first embodiment, the NCR device 500A may retain measurement information as a log when the NCR-MT 520A is in an RRC idle state or an RRC inactive state. Step S2 may include a step of transmitting the retained measurement information (log) to the network 5 when the NCR-MT 520A is in an RRC connected state. This allows the network 5 to grasp the radio environment when the NCR-MT 520A is in an RRC idle state or an RRC inactive state.

[0101] Step S1 may include a step of acquiring location information indicating the location of the NCR device 500A at the time of measurement. The location information may be GNSS location information. Alternatively, the NCR device 500A (NCR-MT 520A) may acquire the location information based on a positioning reference signal received from the network 5. Step S2 may include a step of transmitting the measurement information and location information associated with the measurement information to the network 5. This allows the network 5 to grasp the wireless environment related to the NCR device 500A for each location, making it easier to achieve network optimization.

[0102] (1.4.1) First Operation Pattern The first operation pattern according to the first embodiment will be described with reference to FIG.

[0103] Information that the gNB200 cannot directly know is the status of the access link between the NCR device 500A and the UE100. For example, the gNB200 cannot grasp the received power and / or received quality of the UL signal transmitted from the UE100 and received by the NCR-Fwd 510A. Also, the gNB200 cannot grasp the transmission power of the DL signal of the NCR-Fwd 510A transmitted from the NCR-Fwd 510A to the UE100. Furthermore, in a situation where the NCR-Fwd 510A is autonomously performing transmission power control (gain control), the gNB200 cannot grasp the transmission power of the UL signal of the NCR-Fwd 510A transmitted from the NCR-Fwd 510A to the gNB200. Therefore, by reporting this information from the NCR-MT 520A to the network 5, it becomes easier to realize network optimization.

[0104] As shown in Figure 13, in step S101, NCR-MT520A is in an RRC connected state in the cell of gNB200.

[0105] In step S102, NCR-MT520A may notify gNB200 of its measurement capabilities. For example, in response to an inquiry from gNB200, NCR-MT520A transmits a UE Capability Information message including information on its measurement capabilities to gNB200. Note that the measurement capabilities correspond to the contents of the settings described below.

[0106] In step S103, gNB200 configures radio environment measurement for NCR-MT520A. For example, gNB200 transmits an RRC message including at least one of the following information 1) to 5) to NCR-MT520A.

[0107] 1) Setting the measurement scheme: Either Immediate MDT (Minimization of Drive Test) or Logged MDT is set in the NCR-MT 520A as the measurement scheme. Immediate MDT is a scheme in which the NCR-MT 520A in the RRC connected state immediately reports the measurement results to the network 5. Logged MDT is a scheme in which the NCR-MT 520A in the RRC idle state or the RRC inactive state retains (logs) the measurement results and reports the measurement results to the network 5 later.

[0108] 2) Setting of the NCR-Fwd 510A to be measured: In particular, when the NCR device 500A is configured to include a plurality of NCR-Fwds 510A, the measurement setting in step S103 includes an identifier indicating the NCR-Fwd 510A to be measured.

[0109] 3) Setting of measurement contents: The measurement contents are basically the values ​​measured at the transmitting and receiving ends (antenna ends) of the NCR-Fwd 510A. At least one of the following 3-1) to 3-4) may be set in the NCR-MT 520A as the measurement contents.

[0110] 3-1) UL reception measurement of access link: The UL reception measurement of the access link may be a measurement of received power ([dBm]) such as RSRP. The UL reception measurement may be a measurement of received quality ([dB]) such as RSRQ or SINR. The UL reception measurement of the access link may be a measurement of received power and / or received quality of a partial band.

[0111] 3-2) Access Link DL Transmission Measurement: The access link DL transmission measurement may be the full-band power ([dBm]) and / or the gain ([dB]) of the NCR-Fwd 510A. The access link DL transmission measurement may be the partial-band power ([dBm]) and / or the gain ([dB]) of the NCR-Fwd 510A. Note that the term "gain" used in this specification may also mean amplification gain (the same applies hereinafter).

[0112] 3-3) UL Transmission Measurement of Backhaul Link: The UL transmission measurement of the backhaul link may be the power ([dBm]) of the entire band and / or the gain ([dB]) of the NCR-Fwd 510A. The UL transmission measurement of the backhaul link may be the power ([dBm]) of a partial band and / or the gain ([dB]) of the NCR-Fwd 510A.

[0113] 3-4) DL reception measurement of backhaul link: DL reception measurement of backhaul link may be reception power ([dBm]) such as RSRP. DL reception measurement of backhaul link may be reception quality ([dB]) such as RSRQ / SINR. DL reception measurement of backhaul link may be reception power and / or reception quality of partial bands.

[0114] 4) Setting of measurement target frequency / time: The measurement target frequency / time setting may be a frequency-related setting, for example, a combination of a center frequency and a bandwidth, or a combination of a lower limit frequency and an upper limit frequency. The frequency-related setting may be a combination of a starting PRB number and the number of PRBs, or a combination of a starting subcarrier number and the number of subcarriers. The measurement target time setting may be a time-direction setting, for example, a combination of a starting radio frame number (SFN) and a period. The time-direction setting may be a setting in units of slots, subframes, or symbols.

[0115] 5) Setting the type of trigger event for logging or reporting: Any of the following 5-1) to 5-3) may be set in the NCR-MT 520A as the type of logging or reporting.

[0116] 5-1) Event Trigger: The NCR-MT 520A measures the radio environment and performs logging (in the case of Logged MDT) or reporting (in the case of Immediate MDT) when the measurement result (RSRP / RSRQ / SINR or the above-mentioned measurement values ​​equivalent thereto) exceeds or falls below a threshold. Such a threshold may be set in the NCR-MT 520A. A TTT (Time-to-Trigger) may also be set in the NCR-MT 520A. When the TTT is set, the NCR-MT 520A triggers logging or reporting in response to the threshold condition being satisfied for the TTT time.

[0117] 5-2) Event-triggered periodic: The NCR-MT 520A starts logging or reporting when the event occurs, and performs logging or reporting at regular intervals (for a certain period). The regular intervals (periodicity) and / or the regular duration (duration) may be set in the NCR-MT 520A.

[0118] 5-3) Periodic: The periodicity of the logging or reporting may be set in the NCR-MT520A.

[0119] In step S104, the NCR-MT 520A may transition to an RRC idle state or an RRC inactive state (in the case of Logged MDT), or may remain in an RRC connected state (in the case of Immediate MDT).

[0120] In step S105, the NCR-MT520A performs at least one of the following measurements 1) to 4) according to the settings made in step S103.

[0121] 1) UL reception measurement of access link: The NCR-MT 520A measures the UL signal from the UE 100. The NCR-MT 520A may measure a specific band (specific PRB, specific subcarrier). The NCR-MT 520A may also measure the entire band at once.

[0122] 2) Access link DL transmission measurement: If the NCR-Fwd 510A has an analog detector at the transmitting end (antenna end), it may measure the entire band at once. If feedback is performed from the transmitting end (antenna end) of the NCR-Fwd 510A to the NCR-MT 520A and digital detection (demodulation and measurement) is performed, the power of a partial band may be measured. The gain set in the NCR-Fwd 510A may also be obtained as the measured value. Alternatively, the gain of the NCR-Fwd 510A may be measured by having a detector similar to the above at the receiving end (antenna end) of the NCR-Fwd 510A.

[0123] 3) UL transmission measurement of backhaul link: This is assumed to be the same as the DL transmission measurement of access link described above.

[0124] 4) DL reception measurement: Measurement is performed using the receiver 521 (detector) of the NCR-MT520A.

[0125] Steps S106 to S109 are operations in the case of Logged MDT.

[0126] In step S106, the NCR-MT 520A in the RRC idle state or the RRC inactive state may store the measurement results of step S105 as a log (logging). Here, the NCR-MT 520A may store additional information such as the measurement date and time (timestamp) of step S105 and the measurement position (latitude, longitude, and altitude) of step S105 in addition to the measurement results.

[0127] In step S107, the NCR-MT 520A may transition from the RRC idle state or the RRC inactive state to the RRC connected state.

[0128] In step S108, NCR-MT520A notifies network 5 (gNB200) that it has a log when the RRC connection is established or restored.

[0129] In step S109, network 5 (gNB200) sends a UE Information Request to NCR-MT520A.

[0130] In step S110, NCR-MT520A in the RRC connected state includes a log in a UE Information Response message and sends it to network 5 (gNB200).

[0131] On the other hand, in the case of Immediate MDT, in step S110, the NCR-MT 520A in the RRC connected state transmits a Measurement Report message including the measurement results of step S105 to the network 5 (gNB 200). Alternatively, the NCR-MT 520A may transmit uplink control information (UCI) including the measurement results of step S105 on the PUCCH (Physical Up-link Control Channel). The NCR-MT 520A may transmit a MAC CE (Control Element) including the measurement results of step S105. The report of step S110 may include additional information such as the measurement location (latitude, longitude, altitude) of step S105.

[0132] In step S111, network 5 (gNB200) may use the information of step S110 to perform at least one of the following operations 1) to 3).

[0133] 1) Optimize the transmission power of gNB200 (this may also be transmission power allocation for each UE100): For example, if the gain of NCR device 500A is sufficient for UE100 under NCR device 500A, adjust the transmission power from gNB200 to be lowered (i.e., NCR device 500A still amplifies properly and the same amount of power reaches UE100).

[0134] 2) Optimize coverage by NCR device 500A: For example, if the DL input SINR to NCR device 500A is poor, move the antenna installation position of NCR device 500A closer to gNB200, or adjust the antenna directivity direction of NCR device 500A toward gNB200 (or the direction where interference is expected).

[0135] 3) Determine whether UE100 is under the control of NCR device 500A and / or the probability of presence, etc., and optimize the operation of NCR device 500A: For example, during times when there are not many UE100 under the control of NCR device 500A, drop NCR device 500A into RRC idle state.

[0136] In addition, when the NCR device 500A can grasp the number of UEs 100 under its control, it may log or report this information. For example, the NCR device 500A may use a proximity sensor and / or a radar to detect whether the UEs 100 are under its control.

[0137] (1.4.2) Second Operation Pattern The second operation pattern of the first embodiment will be described below, focusing on the differences from the first operation pattern described above, with reference to Fig. 14. The second operation pattern may be implemented in combination with the first operation pattern described above.

[0138] As described above, it is assumed that the NCR-Fwd 510A is controlled to be turned off in various events, such as at least one of the following events 1) to 5).

[0139] 1) NCR-MT520A in RRC inactive state reselected a cell different from the cell where the latest settings were made.

[0140] 2) NCR-MT520A in the RRC connected state detects a radio link failure (RLF) and initiates RRC re-establishment.

[0141] 3) NCR-MT520A in the RRC inactive state has transitioned to the RRC idle state.

[0142] 4) NCR-MT520A in RRC inactive state is unable to find a suitable cell and camps on an acceptable cell, or enters a camped on any cell state.

[0143] 5) The NCR-MT520A detects a beam failure or fails to recover from the beam failure.

[0144] From the viewpoint of the network 5, all of these can be said to be abnormal states in which the NCR-Fwd 510A is not intentionally turned off. Therefore, it is considered that storing (logging) the wireless environment when the NCR-Fwd 510A is controlled to be turned off can be used for network optimization. In the second operation pattern, in response to the off control of switching the NCR-Fwd 510A from the on state to the off state, the NCR-MT 520A measures and stores the wireless environment.

[0145] As shown in Figure 14, in step S201, NCR-MT520A is in an RRC connected state in the cell of gNB200.

[0146] In step S202, NCR-MT 520A may notify gNB 200 of its measurement capabilities. For example, in response to an inquiry from gNB 200, NCR-MT 520A transmits a UE Capability Information message to gNB 200, the message including information on the measurement and retention capabilities when NCR-Fwd 510A is off.

[0147] In step S203, the gNB200 may configure the NCR-MT520A to record when the NCR-Fwd510A is turned off (when the NCR device 500A voluntarily controls the NCR-Fwd510A to be turned off). This configuration may include configuration information similar to that of the first operation pattern described above. At this point, the NCR-MT520A controls (turns on) the NCR-Fwd510A in accordance with the configuration (NCR configuration information) from the gNB200. The NCR-MT520A may be in an RRC connected state or an RRC inactive state (step S204).

[0148] In step S205, the NCR-MT 520A determines whether or not the NCR-Fwd 510A has been stopped (turned off). If the NCR-Fwd 510A has been stopped (turned off), in step S206, at least one of the following 1) to 3) is stored as a log.

[0149] 1) Occurring Event: The NCR-MT520A includes in the log information indicating the occurring event among the following events 1-1) to 1-6).

[0150] 1-1) A cell different from the cell where the latest settings were made was reselected.

[0151] 1-2) RRC Reestablishment has begun.

[0152] 1-3) The state has transitioned from the RRC inactive state to the RRC idle state. The state may also be that the station camped on an acceptable cell in the RRC inactive state or that the station entered a camped on any cell state.

[0153] 1-4) No suitable cells were found.

[0154] 1-5) Beam failure was detected. Beam failure recovery may have failed.

[0155] 1-6) It may be any other event that controls the NCR-Fwd 510A to be turned off.

[0156] 2) Wireless Environment: The NCR-MT520A includes in the log the measurement results of at least one of the following wireless environments 2-1) to 2-4).

[0157] 2-1) DL received power or received quality (RSRP, RSRQ, SINR) of the backhaul link.

[0158] 2-2) UL transmit power of the backhaul link.

[0159] 2-3) UL received power of the access link.

[0160] 2-4) DL transmission power of the access link.

[0161] 3) The NCR-MT 520A may store the time (timestamp) when the NCR-Fwd 510A was turned off and the location (latitude, longitude, altitude) when the NCR-Fwd 510A was turned off as accompanying information of the log.

[0162] In step S206, the radio environment measurement may be stopped in response to the NCR-Fwd 510A being turned on (again). The gNB 200 may set in step S203 that the radio environment measurement is stopped when the NCR-Fwd 510A is turned on.

[0163] Steps S207 to S212 are the same as those in the first operation pattern described above. Specifically, in step S211, the NCR-MT 520A transmits a log to the gNB 200.

[0164] (1.4.3) Third Operation Pattern The third operation pattern of the first embodiment will be described, focusing on differences from the first and second operation patterns, with reference to Figures 15 and 16. The third operation pattern may be implemented in combination with the first operation pattern and / or the first operation pattern.

[0165] The third operation pattern is an operation pattern related to beam fault detection and recovery performed by the NCR-MT520A.

[0166] First, an overview of general beam failure detection and recovery will be described. General beam failure detection (also referred to as "BFD") and beam failure recovery (also referred to as "BFR") are performed by a UE 100 in an RRC connected state. For beam failure detection, the gNB 200 configures the UE 100 with SSB or CSI (Channel State Information)-RS as a reference signal (RS) for BFD. The MAC entity of the UE 100 in the RRC connected state declares (detects) beam failure when the number of beam failure instance indicators from the physical layer reaches a threshold (maximum count value) set by the gNB 200 before the timer set by the gNB 200 expires.

[0167] After beam failure is detected in the primary cell (PCell), the MAC entity of UE100 does the following: - triggers BFR by initiating a random access procedure in the PCell; - selects an appropriate beam to perform BFR (if the gNB200 provides dedicated random access resources for a specific beam, it is prioritized by UE100); - if the random access procedure includes contention-based random access, includes an indicator of beam failure in the PCell in the BFR (Beam Failure Recovery) MAC CE (Control Element).

[0168] When the random access procedure is completed, the UE 100 considers that the BFR of the PCell is completed.

[0169] On the other hand, as described above, the NCR device 500A can continue relaying operations according to the latest NCR setting even if the NCR-MT 520A transitions from the RRC connected state to the RRC inactive state. Therefore, in the third operation pattern, the NCR-MT 520A executes BFD and BFR even in the RRC inactive state.

[0170] FIG. 15 is a diagram for explaining an operation scenario according to the third operation pattern.

[0171] As shown in STEP 1 of FIG. 15 , the NCR device 500A is in an RRC connected state in the cell of the gNB 200. The gNB 200 transmits an RRC Reconfiguration message including the NCR configuration to the NCR device 500A. The NCR device 500A receives the RRC Reconfiguration message including the NCR configuration from the gNB 200 and performs relay operation using the NCR configuration. The NCR configuration may include a periodic beam indication. That is, the NCR configuration includes information for configuring relay operation with periodic beamforming, and the NCR-Fwd 510A is set to on. The NCR-MT 520A receives configuration information regarding relay operation from the gNB 200.

[0172] As shown in STEP 2 of Figure 15, gNB200 transmits an RRC Release message including a suspend setting to NCR device 500A. NCR device 500A receives the RRC Release message from gNB200 and transitions to an RRC inactive state.

[0173] The RRC Reconfiguration message sent from gNB200 to NCR-MT520A in STEP 1, or the RRC Release message sent from gNB200 to NCR-MT520A in STEP 2, may include configuration information regarding whether NCR-MT520A will perform beam failure detection processing (BFD) with gNB200 in an RRC inactive state.

[0174] As shown in STEP 3 of FIG. 15, after the NCR-MT 520A transitions to the RRC inactive state, the NCR-MT 520A controls the NCR-Fwd 510A in accordance with the latest NCR setting.

[0175] The basic BFD operation performed by the NCR-MT 520A in the RRC inactive state may be an operation that applies general BFD. The MAC entity of the NCR-MT 520A may perform BFD in the RRC inactive state by continuing to use the reference signal (RS), timer value, and maximum count value for BFD set by the gNB 200 when in the RRC connected state. Specifically, the MAC entity of the NCR-MT 520A in the RRC inactive state declares (detects) beam failure when the number of beam failure instance indicators from the physical layer reaches a threshold (maximum count value) set by the gNB 200 before the timer set by the gNB 200 expires. Alternatively, at least one of the reference signal (RS), timer value, and maximum count value for the RRC inactive state may be a parameter independent of the reference signal (RS), timer value, and maximum count value for the RRC connected state.

[0176] FIG. 16 is a diagram showing the operation of the mobile communication system 1 according to the third operation pattern.

[0177] As shown in Figure 16, in step S301, NCR-MT520A is in an RRC connected state in the cell of gNB200.

[0178] In step S302, NCR-MT520A may notify gNB200 of its beam measurement capability in the RRC inactive state. For example, in response to an inquiry from gNB200, NCR-MT520A transmits a UE Capability Information message to gNB200, the message including information on its beam measurement capability in the RRC inactive state.

[0179] In step S303, the gNB200 may configure the NCR-MT520A to perform beam recording when in the RRC inactive state. At this point, the NCR-MT520A in the RRC connected state controls (turns on) the NCR-Fwd510A according to the setting (NCR setting information) from the gNB200.

[0180] In step S304, the NCR-MT 520A transitions from the RRC connected state to the RRC inactive state. The NCR-MT 520A continues to control (on) the NCR-Fwd 510A in accordance with the latest setting (latest NCR setting information) from the gNB 200.

[0181] In steps S305 and S306, the NCR-MT 520A in the RRC inactive state stores at least one of the following information 1) to 3) (beam monitoring information under the control of the NCR-Fwd 510A) in a log.

[0182] 1) Selected beam information: 1-1) SSB index of selected beam: The NCR-MT520A may keep the SSB index of the selected beam in a log.

[0183] 1-2) SSB index of a beam in which a beam failure is detected: The NCR-MT520A may store in a log the SSB index of a beam in which a beam failure is detected. The NCR-MT520A may store in a log the SSB index of a beam after beam failure recovery.

[0184] 2) Radio environment: For example, the NCR-MT 520A stores the DL received power and / or received quality (RSRP, RSRQ, SINR) of the backhaul link in a log. The NCR-MT 520A may store the measurement values ​​for each SSB index in the log, in association with the SSB index of the selected beam.

[0185] When CSI-RS (Channel State Information RS) is used instead of SSB to identify the beam, the setting index of the CSI-RS of the measured beam may be stored in the log instead of the SSB index. Also, when the CSI-RS of the measured beam is linked to SSB, the linked SSB index may be stored in the log.

[0186] For example, the NCR-MT520A stores the following information in a log: SSB index #10, best beam (selected), RSRP=-80 dBm SSB index #21, (neighbor beam), RSRP=-88 dBm SSB index #8, (neighbor beam), RSRP=-93 dBm . . .

[0187] 3) The NCR-MT520A may store the time (timestamp) when the measurement or beam disturbance occurred, and the location (latitude, longitude, and altitude) where the measurement or beam disturbance occurred as accompanying information.

[0188] In the above operation example, it is assumed that NCR-Fwd510A is on when NCR-MT520A's RRC is inactive, but NCR-MT520A does not need to retain logs if NCR-Fwd510A is off in accordance with the latest settings from gNB200.

[0189] Steps S307 to S311 are the same as those in the first operation pattern described above. Specifically, in step S211, the NCR-MT 520A transmits a log to the gNB 200.

[0190] (2) Second Embodiment Next, a second embodiment will be described, focusing on differences from the above-described embodiments. As shown in Fig. 17, the relay device according to the second embodiment is a Reconfigurable Intelligent Surface (RIS) device 500B that changes the propagation direction of an incident radio wave (wireless signal) by reflection or refraction. The term "NCR" in the above-described embodiments can be read as "RIS."

[0191] RIS is a type of repeater (hereinafter also referred to as "RIS-Fwd") that can perform beamforming (directivity control) similar to NCR by changing the properties of a metamaterial. In the case of RIS, the range (distance) of the beam may also be changed by controlling the reflection direction and / or refraction direction of each unit element. For example, the RIS may be configured to control the reflection direction and / or refraction direction of each unit element and to focus (direct the beam) on a nearby UE or a distant UE.

[0192] The RIS device 500B has a new UE (hereinafter referred to as "RIS-MT") 520B, which is a control terminal for controlling the RIS-Fwd 510B. The RIS-MT 520B establishes a wireless connection with the gNB 200 and performs wireless communication with the gNB 200, thereby controlling the RIS-Fwd 510B in cooperation with the gNB 200. The RIS-Fwd 510B may be a reflective RIS. Such a RIS-Fwd 510B changes the propagation direction of incident radio waves by reflecting the radio waves. Here, the reflection angle of the radio waves is variably settable. The RIS-Fwd 510B reflects radio waves incident from the gNB 200 toward the UE 100. The RIS-Fwd 510B may be a transparent RIS. Such a RIS-Fwd 510B changes the propagation direction of the radio waves by refracting the incident radio waves. Here, the refraction angle of the radio wave can be variably set.

[0193] FIG. 18 is a diagram showing an example configuration of a RIS-Fwd (repeater) 510B and a RIS-MT (control terminal) 520B according to the second embodiment. The RIS-MT 520B includes a receiver 521, a transmitter 522, and a controller 523. The RIS-MT 520B may include a GNSS receiver 524. The GNSS receiver 524 may be provided in the RIS-MT 520B. This configuration is similar to that of the above-described embodiment. The RIS-Fwd 510B includes a RIS 511B and a RIS controller 512B. The RIS 511B is a metasurface formed using a metamaterial. For example, the RIS 511B is configured by arranging structures that are very small relative to the wavelength of radio waves in an array. By varying the shape of the structures depending on their placement, the direction and / or beam shape of the reflected waves can be arbitrarily designed. The RIS 511B may be a transparent dynamic metasurface. The RIS 511B may be configured by overlaying a transparent glass substrate on a transparent metasurface substrate on which a large number of small structures are regularly arranged, and by slightly moving the overlaid glass substrate, it may be possible to dynamically control three patterns: a mode that transmits incident radio waves, a mode that transmits some of the radio waves and reflects some of them, and a mode that reflects all of the radio waves. The RIS control unit 512B controls the RIS 511B in response to a RIS control signal from the control unit 523 of the RIS-MT 520B. The RIS control unit 512B may include at least one processor and at least one actuator. The processor decodes the RIS control signal from the control unit 523 of the RIS-MT 520B and drives the actuator in response to the RIS control signal.

[0194] The RIS-Fwd 510B may have a measurement unit 513B. The measurement unit 513B may be arranged in the RIS-MT 520B. As in the first embodiment, the measurement unit 513B may measure an uplink (UL) signal from the UE 100 to the RIS-Fwd 510B in the access link. The measurement unit 513B may measure a DL signal from the gNB 200 to the RIS-Fwd 510B in the backhaul link. For measurements of DL signals from the gNB 200 to the NCR-Fwd 510A, the measurement unit 513B may be at least partially shared with the receiving unit 521 of the NCR-MT 520A.

[0195] (3) Other Embodiments In the above-described embodiment, an example has been described in which the relay device that performs relay transmission is the NCR device 500A or the RIS device 500B. However, the relay device that performs relay transmission is not limited to the NCR device 500A or the RIS device 500B, and may be an IAB (Integrated Access and Backhaul) node defined in the 3GPP technical specifications.

[0196] The above-described operational flows are not limited to being implemented independently, but can also be implemented by combining two or more operational flows. For example, some steps of one operational flow may be added to another operational flow, or some steps of one operational flow may be replaced with some steps of another operational flow. In each flow, it is not necessary to execute all steps, and only some steps may be executed.

[0197] In the above embodiment, an example in which the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB). The base station may also be a relay node such as an IAB node. The base station may also be a Distributed Unit (DU) of the IAB node. The UE 100 may also be a Mobile Termination (MT) of the IAB node.

[0198] That is, the UE 100 may be a terminal function unit (a type of communication module) for a base station to control a repeater that relays signals. Such a terminal function unit is referred to as an MT. Examples of the MT include, in addition to the IAB-MT, an NCR (Network Controlled Repeater)-MT and a RIS (Reconfigurable Intelligent Surface)-MT.

[0199] The term "network node" primarily refers to a base station, but may also refer to a core network device or a part of a base station (CU, DU, or RU). A network node may also be configured by a combination of at least a part of a core network device and at least a part of a base station.

[0200] A program may be provided that causes a computer to execute each process performed by a communication device according to the above-described embodiment, for example, the UE 100 (NCR-MT520A, RIS-MT520B), the gNB 200, or the relay device. The program may be recorded on a computer-readable medium. Using a computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by the UE 100, the gNB 200, or the relay device may be integrated, and at least a portion of the UE 100, the gNB 200, or the relay device may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0201] The functions performed by the UE 100, the gNB 200 (network node), or the relay device may be implemented in circuitry or processing circuitry, including general-purpose processors, application-specific processors, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (a Central Processing Unit), conventional circuits, and / or combinations thereof, programmed to perform the described functions. A processor includes transistors and other circuits and is considered to be circuitry or processing circuitry. A processor may also be a programmed processor that executes a program stored in memory. In this specification, circuitry, unit, or means refers to hardware that is programmed to perform the described functions or hardware that executes them. The hardware may be any hardware disclosed herein or any hardware known to be programmed or capable of performing the described functions. If the hardware is a processor, the circuitry, means, or unit is a combination of hardware and software used to configure the hardware and / or processor.

[0202] As used in this disclosure, the terms "based on" and "depending on / in response to" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "depending only on" and "depending at least in part on." The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Additionally, the term "or," as used in this disclosure, is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0203] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention.

[0204] This application claims priority from Japanese Patent Application No. 2023-096093 (filed June 12, 2023), the entire contents of which are incorporated herein by reference.

[0205] (4) Supplementary Notes The following are additional notes regarding the features of the above-described embodiment.

[0206] (Supplementary Note 1) A communication method executed by a relay device having a relay device that performs a relay operation to relay a radio signal transmitted between a network and a user device, and a control terminal that receives a control signal used to control the relay device from the network, the communication method comprising: a step of measuring a radio environment related to the relay device; and a step of transmitting measurement information obtained by the measurement from the control terminal to the network.

[0207] (Supplementary Note 2) The communication method according to Supplementary Note 1, wherein the measuring step includes a step of measuring a radio environment of an access link between the relay device and the user device.

[0208] (Supplementary Note 3) The communication method according to Supplementary Note 2, wherein the step of measuring a radio environment of the access link includes a step of measuring a received power and / or a received quality of an uplink radio signal received by the relay device from the user equipment.

[0209] (Supplementary Note 4) The communication method according to Supplementary Note 2, wherein the step of measuring a radio environment of the access link includes the step of measuring transmission power of a downlink radio signal transmitted from the relay device to the user equipment.

[0210] (Supplementary Note 5) The communication method according to any one of Supplementary Notes 1 to 4, wherein the measuring step includes a step of measuring a transmission power of an uplink radio signal transmitted from the relay device to the network.

[0211] (Supplementary Note 6) The communication method according to any one of Supplementary Notes 1 to 5, wherein the measuring step includes a step of measuring and maintaining the wireless environment in response to an off control being performed to switch the repeater from an on state to an off state.

[0212] (Supplementary Note 7) The communication method according to any one of Supplementary Notes 1 to 6, wherein the measuring step includes a step of measuring the state of a beam formed by a network node included in the network.

[0213] (Supplementary Note 8) The communication method according to any one of Supplementary Notes 1 to 7, wherein the measuring step includes a step of measuring the radio environment when the control terminal is in a radio resource control (RRC) connected state, and the transmitting step includes a step of transmitting the measurement information to the network when the control terminal is in the RRC connected state.

[0214] (Supplementary Note 9) The communication method according to any one of Supplementary Notes 1 to 7, further comprising the step of retaining the measurement information when the control terminal is in a radio resource control (RRC) idle state or an RRC inactive state, and wherein the transmitting step includes the step of transmitting the retained measurement information to the network when the control terminal is in an RRC connected state.

[0215] (Supplementary Note 10) The communication method according to any one of Supplementary Notes 1 to 9, further comprising the step of acquiring location information indicating a location of the relay device at the time of the measurement, wherein the transmitting step includes the step of transmitting the measurement information and the location information associated with the measurement information to the network.

[0216] (Supplementary Note 11) A relay device comprising: a repeater that performs a relay operation to relay a radio signal transmitted between a network and a user device; and a control terminal that receives a control signal used to control the repeater from the network, wherein the control terminal measures a radio environment related to the relay device, and transmits measurement information obtained by the measurement from the control terminal to the network.

[0217] 1: Mobile communication system 100: UE 200: gNB 210: Transmitter 220: Receiver 230: Controller 240: Backhaul communication unit 300A: AMF 400: OAM server 500A: NCR device 510A: NCR-Fwd 520A: NCR-MT 500B: RIS device 510B: RIS-Fwd 520B: RIS-MT 511A: Wireless unit 511a: Antenna unit 511b: RF circuit 511c: Directivity control unit 511d: Measurement unit 512A: NCR control unit 512B: RIS control unit 513B: Measurement unit 521: Receiver 522: Transmitter 523 : Control unit 524 : GNSS receiver 530 : Interface

Claims

1. A communication method implemented by a relay device having a relaying operation for relaying radio signals transmitted between a network and a user device, and a control terminal for receiving a control signal used to control the relay device from the network, the communication method comprising: measuring a radio environment related to the relay device; and transmitting measurement information obtained by the measurement from the control terminal to the network.

2. The communication method according to claim 1, wherein the measuring step includes measuring a radio environment of an access link between the relay device and the user device.

3. The communication method according to claim 2, wherein measuring the radio environment of the access link includes measuring the reception power and / or reception quality of an uplink radio signal received by the relay device from the user device.

4. The communication method according to claim 2, wherein measuring the radio environment of the access link includes measuring the transmission power of a downlink radio signal transmitted from the relay device to the user equipment.

5. The communication method according to claim 1, wherein said measuring includes measuring a transmission power of an uplink radio signal transmitted from said relay device to said network.

6. The communication method according to claim 1, wherein the measuring step includes measuring and maintaining the wireless environment in response to an off control being performed to switch the repeater from an on state to an off state.

7. The communication method according to claim 1, wherein said measuring includes measuring a state of a beam formed by a network node included in said network.

8. A communication method according to any one of claims 1 to 7, wherein the measuring includes measuring the radio environment when the control terminal is in a radio resource control (RRC) connected state, and the transmitting includes transmitting the measurement information to the network when the control terminal is in the RRC connected state.

9. The communication method according to any one of claims 1 to 7, further comprising: retaining the measurement information when the control terminal is in a Radio Resource Control (RRC) idle state or an RRC inactive state; and wherein the transmitting step includes transmitting the retained measurement information to the network when the control terminal is in an RRC connected state.

10. A communication method according to any one of claims 1 to 7, further comprising obtaining location information indicating the location of the relay device at the time of the measurement, and wherein the transmitting step includes transmitting the measurement information and the location information associated with the measurement information to the network.

11. A relay device comprising: a repeater that performs a relaying operation to relay radio signals transmitted between a network and a user device; and a control terminal that receives a control signal from the network for use in controlling the repeater, wherein the control terminal measures the radio environment related to the relay device and transmits measurement information obtained by the measurement from the control terminal to the network.

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