COMMUNICATION METHOD, REPEATER NODE, PROGRAM, CHIP SET, SYSTEM, AND USER DEVICE

Abstract

A communication method using a relay device including a repeater that performs a relay operation to relay wireless signals 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, comprises: a step for initiating a procedure by the control terminal for transitioning to an RRC connected state in a second cell, when the control terminal is in a radio resource control (RRC) idle state or an RRC inactive state in a first cell and the repeater is on; and a step for turning off the repeater by the relay device on the basis of the initiation of the procedure.

Description

[Technical Field]

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

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

[0003] Radio 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 poses a problem of reducing the coverage of base stations. To solve this problem, repeater devices, which are a type of relay device that relays radio signals between a network and user devices and can be controlled from a network, have been attracting attention (see, for example, Non-Patent Document 1). Such repeater devices can expand the coverage of base stations while suppressing interference, for example, by amplifying radio signals received from base stations and transmitting them directionally. Such repeater devices are also called NCRs (Network-Controlled Repeaters). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP contribution: RP-213700, “New SI: Study on NR Network-controlled Repeaters” Summary of the Invention

[0005] A communication method according to a first aspect is a communication method using a relay device having a relay device that performs a relay 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 used to control the relay device, and includes the steps of: causing the relay device to continue the relay operation when the control terminal transitions from a Radio Resource Control (RRC) connected state to an RRC inactive state; when the control terminal is in an RRC inactive state, the control terminal initiating a procedure to restore to an RRC connected state; receiving from the network a message to turn off the relay device based on the initiation of the procedure; and causing the relay device to stop the relay operation when the relay device receives the message.

[0006] A communication method according to a second aspect is a communication method using a relay device having a relay that performs relaying operations to relay radio signals transmitted between a network and a user equipment, and a control terminal that receives a control signal from the network used to control the relay, and includes the steps of: when the control terminal is in a radio resource control (RRC) idle state or an RRC inactive state in a first cell and the relay is on, the control terminal initiating a procedure for transitioning to an RRC connected state for a second cell; and, based on the initiation of the procedure, the relay device turning off the relay.

[0007] A relay device according to a third aspect comprises a relay that performs relaying operations to relay radio signals transmitted between a network and a user device, and a control terminal that receives a control signal from the network used to control the relay, wherein the control terminal initiates a procedure for transitioning to an RRC connected state for a second cell when the control terminal is in a radio resource control (RRC) idle state or an RRC inactive state in a first cell and the relay is on, and turns off the relay based on the initiation of the procedure. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. [Figure 2] FIG. 10 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data. [Figure 3] FIG. 1 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals). [Figure 4] FIG. 1 is a diagram illustrating an example of an application scenario of an NCR device (relay device) according to an embodiment. [Figure 5] FIG. 1 is a diagram illustrating an example of an application scenario of an NCR device according to an embodiment. [Figure 6] FIG. 10 is a diagram illustrating an example of a control method for an NCR device according to an embodiment. [Figure 7] 1 is a diagram illustrating an example of the configuration of a protocol stack in a mobile communication system having an NCR device according to an embodiment. [Figure 8] 1 is a diagram showing a specific example of the configuration of a mobile communication system 1 having an NCR device according to an embodiment. [Figure 9] FIG. 1 is a diagram illustrating an example of the configuration of an NCR device according to an embodiment. [Figure 10] 1 is a diagram illustrating a configuration of a UE (user equipment) according to an embodiment. [Figure 11] A diagram showing an example configuration of a gNB (base station) according to an embodiment. [Figure 12] FIG. 1 is a diagram illustrating a general cell reselection procedure. [Figure 13] FIG. 4 is a diagram for explaining the operation according to the first embodiment. [Figure 14] FIG. 2 is a diagram illustrating an example of the operation of the NCR device according to the first embodiment. [Figure 15] FIG. 10 is a diagram illustrating an example of the operation of the NCR device according to the first modification of the first embodiment. [Figure 16] FIG. 10 is a diagram illustrating an example of the operation of an NCR device according to a second modification of the first embodiment. [Figure 17]FIG. 10 is a diagram illustrating an example of operation of a mobile communication system according to a third modification of the first embodiment. [Figure 18] FIG. 10 is a diagram illustrating an example of an operation according to the second embodiment. [Figure 19] FIG. 10 is a diagram for explaining another example of the operation according to the second embodiment. [Figure 20] FIG. 10 is a diagram illustrating an example of the operation of the NCR device according to the second embodiment. [Figure 21] FIG. 10 is a diagram illustrating an example of the operation of the NCR device according to the second embodiment. [Figure 22] FIG. 10 is a diagram for explaining a RIS device (relay device) according to the third embodiment. [Figure 23] FIG. 10 is a diagram for explaining a RIS device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] (1) First embodiment First, a description will be given of a first embodiment. A relay device according to the embodiment is a repeater device (that is, an NCR device) that can be controlled from a network.

[0011] (1.1) Overview of mobile communication systems FIG. 1 is a diagram showing a configuration of a mobile communication system according to an embodiment.

[0012] 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 sixth generation (6G) system.

[0013] 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. 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.

[0014] The UE 100 is a mobile wireless communication device. The UE 100 may be any device used by a user. For example, the UE 100 may be a mobile phone terminal (including a smartphone) and / or a tablet terminal, a laptop 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).

[0015] 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 a UE 100 that has established a connection with its own cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, 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 that performs wireless communication with a UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0016] The gNB 200 may be functionally divided into a central unit (CU) and distributed units (DUs). The CU controls the DUs. 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 DUs form cells. The DU 202 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.

[0017] In addition, gNBs can also connect to the Evolved Packet Core (EPC), which is the LTE core network. LTE base stations can also connect to 5GC. LTE base stations and gNBs can also be connected via a base station-to-base station interface.

[0018] The 5GC20 includes an Access and Mobility Management Function (AMF) and a User Plane Function (UPF) 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 UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

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

[0020] 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.

[0021] 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.

[0022] The gNB 200 also transmits a synchronization signal block (SSB: Synchronization Signal / PBCH block). For example, the SSB is composed of four consecutive Orthogonal Frequency Division Multiplex (OFDM) symbols, and includes a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a Physical Broadcast Channel (PBCH) / Master Information Block (MIB), and a Demodulation Reference Signal (DMRS) for the PBCH. The bandwidth of the SSB is, for example, 240 consecutive subcarriers, i.e., a bandwidth of 20 RBs.

[0023] 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 UE100 and the MAC layer of gNB200 via transport channels. The MAC layer of gNB200 includes a scheduler, which determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to UE100.

[0024] The RLC layer transmits data to the RLC layer on the receiving side 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 logical channels.

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

[0026] The SDAP layer maps IP flows, which are the units for Quality of Service (QoS) control by the core network, to radio bearers, which are the units for QoS control by the Access Stratum (AS). Note that if the RAN is connected to the EPC, SDAP is not necessary.

[0027] 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).

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

[0029] 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.

[0030] 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 referred to as an AS layer.

[0031] (1.2) Example of application scenario for relay devices 4 and 5 are diagrams illustrating an example of an application scenario of the NCR device according to the embodiment.

[0032] 5G / NR enables broadband transmission using higher frequency bands than 4G / LTE. 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 a radio signal can be received directly from the gNB 200. There may be an obstruction between the gNB 200 and the UE 100, preventing the UE 100 from communicating with the gNB 200 within line-of-sight.

[0033] 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 a network is introduced into the mobile communication system 1. Such a repeater device may be referred to as a smart repeater device.

[0034] 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 the radio signal with a fixed directivity (beam). The NCR device 500A may also transmit the radio signal with a variable (adaptive) directional beam. This allows the coverage of the gNB 200 to be efficiently expanded.

[0035] 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 includes an NCR-Fwd (Forward) 510A, which is a type of repeater that relays radio signals transmitted between the gNB 200 and the UE 100, specifically, that changes the propagation state of the radio signals without demodulating or modulating the radio signals, and an NCR-MT 520A that controls the NCR-Fwd 510A by wirelessly communicating with the gNB 200. In this way, the NCR-MT 520A establishes a wireless connection with the gNB 200 and communicates wirelessly 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 under control from the gNB 200. The NCR-MT520A also has the same functions as the UE100.

[0036] The NCR-MT520A may be configured separately from the NCR-Fwd510A. For example, the NCR-MT520A may be located near the NCR-Fwd510A and electrically connected to the NCR-Fwd510A. The NCR-MT520A may be connected to the NCR-Fwd510A via a wired or wireless connection. Alternatively, the NCR-MT520A may be configured integrally with the NCR-Fwd510A. The NCR-MT520A and the NCR-Fwd510A may be fixedly installed, for example, at the coverage edge (cell edge) of the gNB200 or on a wall or window of a building. The NCR-MT520A and the NCR-Fwd510A may be mobile, installed in a vehicle, for example. Furthermore, one NCR-MT520A may control multiple NCR-Fwd510A.

[0037] The NCR-MT520A is not limited to a configuration in which it directly controls one or more NCR-Fwd510A, but may also be a configuration in which it indirectly controls one or more NCR-Fwd510A. For example, the NCR-MT520A may control one or more NCR-Fwd510A via a higher layer (e.g., an application layer).

[0038] 5, the NCR device 500A (NCR-Fwd 510A) dynamically or quasi-statically changes a 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 resource 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, in order to suppress interference.

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

[0040] The NCR-MT520A transmits and receives wireless signals (herein referred to as "NCR-MT signals") to and from the gNB200. The NCR-MT signals include uplink signals (herein referred to as "NCR-MT-UL signals") transmitted from the NCR-MT520A to the gNB200 and downlink signals (herein referred to as "NCR-MT-DL signals") transmitted from the gNB200 to the NCR-MT520A. The NCR-MT-DL signals include signaling (e.g., NCR control signals) for controlling the NCR device 500A. The wireless link between the NCR-MT520A and the gNB200 is also referred to as a "control link."

[0041] The gNB200 directs a beam to the NCR-MT520A based on the NCR-MT-UL signal from the NCR-MT520A. Because the NCR device 500A is co-located with the NCR-MT520A, if the backhaul link and the control link have the same frequency, when the gNB200 directs a beam to the NCR-MT520A, the beam is also directed to the NCR-Fwd510A. The gNB200 uses the beam to transmit an NCR-MT-DL signal and a UE-DL signal. The NCR-MT520A receives the NCR-MT-DL signal. Note that when the NCR-Fwd510A and the NCR-MT520A are at least partially integrated, the NCR-Fwd510A and the NCR-MT520A may be integrated with functions (e.g., antennas) for transmitting, receiving, or relaying UE signals and / or NCR-MT signals. 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 the transmitting wave and / or receiving wave in a specific direction by adjusting / adapting the antenna weight, etc.

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

[0043] The NCR-MT520A has at least one layer (entity) of PHY, MAC, RRC, and F1-AP (Application Protocol). The F1-AP is a type of fronthaul interface. The NCR-MT520A exchanges signaling with the gNB200 via at least one of PHY, MAC, RRC, and F1-AP. If the NCR-MT520A is a type or part of a base station, the NCR-MT520A may exchange signaling with the gNB200 via an Xn AP (Xn-AP), which is an interface between base stations. The NCR-MT520A may also have an NAS layer (entity). The NCR-MT520A exchanges signaling with the AMF300A via the NAS layer. The NAS layer may constitute an upper layer for the NCR-MT520A.

[0044] FIG. 8 is a diagram showing a specific example of the configuration of a mobile communication system 1 having an NCR device 500A according to an embodiment.

[0045] A backhaul link is established between the gNB 200 and the NCR-Fwd 510A. An access link is established between the UE 100 and the NCR-Fwd 510A. The NCR-Fwd 510A relays wireless signals transmitted between the gNB 200 and the UE 100 via the backhaul link and the access link. The NCR-Fwd 510A changes the propagation state of the wireless signals without demodulating or modulating the wireless signals.

[0046] In addition, a control link is established between the gNB200 and Layer 1 and / or Layer 2 (L1 / L2) of the NCR-MT520A. The L1 / L2 of the NCR-MT520A transmits and receives L1 / L2 signaling with the gNB200 via the control link. An RRC connection is established between the gNB200 and the RRC of the NCR-MT520A. The RRC of the NCR-MT520A transmits and receives RRC messages with the gNB200 via the RRC connection. The NCR-MT520A receives downlink signaling (also referred to as an "NCR control signal" or simply "control signal") from the gNB200 via the RRC connection and / or the control link.

[0047] The gNB200 (transmitter 210) transmits an NCR control signal to the NCR-MT520A. 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 CE (Control Element), 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-dedicated 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-MT520A is a type or part of a base station, the NCR-MT520A may communicate with the gNB200 via an Xn AP (Xn-AP), which is an inter-base station interface.

[0048] Hereinafter, the NCR control signal transmitted in the 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 setting information" or simply "setting information." Here, the RRC message may be an RRC Reconfiguration message. The NCR setting information includes, for example, information for setting the NCR-Fwd 510A to on / off. The NCR setting information may also include, for example, information on semi-static beam setting of the NCR-Fwd 510A.

[0049] 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 (SCI). 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 for dynamic beam control of the NCR-Fwd 510A. The NCR setting information may include information instructing dynamic on / off of the NCR-Fwd 510A.

[0050] 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 in accordance with the NCR control information (SCI) 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 in accordance with the latest (last) setting information received from the gNB 200.

[0051] The NCR control signal (for example, 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.

[0052] Furthermore, if the NCR-MT520A detects a radio link failure (RLF) with the gNB200, 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 the 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.

[0053] The NCR control signal may include frequency control information that specifies the center frequency of a radio signal (e.g., a component carrier) to be relayed by the NCR-Fwd510A. When the NCR control signal received from the gNB200 includes frequency control information, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A to relay a radio signal having a 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 gNB200 can specify, via the NCR-MT520A, the center frequency of a radio signal to be relayed by the NCR-Fwd510A.

[0054] The NCR control signal may include mode control information that specifies an 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 one of a mode in which the NCR-Fwd 510A performs omnidirectional transmission and / or reception, a mode in which the NCR-Fwd 510A performs fixed-directivity transmission and / or reception, a mode in which the NCR-Fwd 510A performs transmission and / or reception using a variable directional beam, and a mode in which the NCR-Fwd 510A performs MIMO (Multiple Input Multiple Output) relay transmission. The operation mode may be one of a beamforming mode (i.e., a mode that prioritizes improving a desired wave) and a null steering mode (i.e., a mode that prioritizes 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 operation mode indicated by the mode control information (step S2A). When the NCR control signal includes mode control information, the gNB 200 can specify the operation mode of the NCR-Fwd 510A via the NCR-MT 520A.

[0055] Here, the mode in which the NCR device 500A performs non-directional transmission and / or reception is a mode in which the NCR-Fwd510A performs omnidirectional relaying, and may be referred to as omni-mode. The mode in which the NCR-Fwd510A performs fixed-directivity transmission and / or reception may be a directional mode achieved by a single directional antenna. This mode may be a beamforming mode achieved by applying fixed phase and amplitude control (antenna weight control) to multiple antennas. Any of these modes may be specified (set) by the gNB200 to the NCR-MT520A. The mode in which the NCR-Fwd510A 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 UE100 is formed. Any of these modes may be specified (set) by the gNB200 to the NCR-MT520A. In addition, in the operation mode in which beamforming is performed, beam control information, which will be described later, may be provided from the gNB200 to the NCR-MT520A. The mode in which the NCR device 500A performs MIMO relay transmission may be a mode 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) by the gNB200 to the NCR-MT520A. The operation modes may include a mode in which relay transmission by the NCR-Fwd510A is turned on (activated) and a mode in which relay transmission by the NCR-Fwd510A is turned off (deactivated). Any of these modes may be specified (set) by the gNB200 to the NCR-MT520A by an NCR control signal.

[0056] The NCR control signal may include beam control information that specifies the transmission direction, transmission weight, or beam pattern when the NCR-Fwd510A performs directional transmission. The beam control information may be associated with frequency control information (center frequency). The beam control information may include a PMI (Precoding Matrix Indicator). The beam control information may include beam formation angle information. When the NCR control signal received from the gNB200 includes beam control information, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A to form the transmission directivity (beam) indicated by the beam control information. When the NCR control signal includes beam control information, the gNB200 can control the transmission directivity of the NCR device 500A via the NCR-MT520A.

[0057] The NCR control signal may include output control information that specifies the degree to which the NCR-Fwd510A amplifies the radio signal (amplification gain) or transmission power. The output control information may be information indicating a difference (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 gNB200 includes output control information, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A 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-Fwd510A. The output control information may be information that specifies the transmission power of the NCR-Fwd510A.

[0058] When one NCR-MT 520A controls multiple NCR-Fwd 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-Fwd 510A determines the NCR-Fwd 510A to which the NCR control signal should be 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 along with the NCR control signal, even when the NCR-MT 520A controls only one NCR-Fwd 510A.

[0059] In this way, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A based on the NCR control signal from the gNB 200. This enables the gNB 200 to control the NCR-Fwd510A via the NCR-MT520A.

[0060] (1.3) Configuration examples of each device An example of the configuration of each device in the mobile communication system 1 according to the embodiment will be described.

[0061] (1.3.1) Example of relay device configuration 9 is a diagram showing an example of the configuration of an NCR device 500A (relay device) according to the embodiment. The NCR device 500A includes an NCR-Fwd 510A, an NCR-MT 520A, and an interface 530.

[0062] 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 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 a control signal from the NCR-MT 520A. The NCR control unit 512A may include at least one processor.

[0063] The NCR-MT520A has a receiving unit 521, a transmitting unit 522, and a control unit 523. The receiving unit 521 performs various receptions under the control of the control unit 523. The receiving unit 521 includes an antenna and a receiver. The receiver converts a radio signal (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-MT520A. The operations of the NCR-MT520A (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 the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes. The control unit 523 also performs the functions of at least one of the PHY, MAC, RRC, and F1-AP layers.

[0064] 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 a higher layer (e.g., an application layer).

[0065] In the 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.

[0066] (1.3.2) Example of user device configuration 10 is a diagram showing the configuration of a UE 100 (user equipment) according to the 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.

[0067] 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.

[0068] 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.

[0069] 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 under the control of 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, etc. The CPU executes programs stored in the memory to perform various processes.

[0070] (1.3.3) Example of base station configuration 11 is a diagram illustrating a configuration example of a gNB 200 (base station) according to an embodiment. The gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240.

[0071] 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.

[0072] The control unit 230 performs various controls in the gNB 200. The operations of the gNB 200 described above and below may be operations under the control of 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.

[0073] The backhaul communication unit 240 is connected to neighboring 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. Note that the gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally divided), and both units may be connected via an F1 interface.

[0074] In the 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 by wireless communication, thereby enabling the gNB 200 to control the NCR device 500A via the NCR-MT 520A.

[0075] (1.4) Overview of cell reselection The NCR-MT520A supports cell reselection in RRC idle or RRC inactive states.

[0076] FIG. 12 is a diagram illustrating a general cell reselection procedure. The NCR-MT520A in the RRC idle state or the RRC inactive state performs the cell reselection procedure to transition from the current serving cell to a neighboring cell. Specifically, the NCR-MT520A identifies a neighboring cell on which it should camp by the cell reselection procedure, and reselects the identified neighboring cell. Note that the case where the current serving cell and the neighboring cell have the same frequency (carrier frequency) is called intra-frequency, and the case where the current serving cell and the neighboring cell have different frequencies (carrier frequencies) is called inter-frequency. The current serving cell and the neighboring cell may be managed by the same gNB200. The current serving cell and the neighboring cell may also be managed by different gNB200s.

[0077] In step S11, the NCR-MT 520A performs frequency prioritization processing based on the priority (also referred to as "absolute priority", "cell reselection priority", or "dedicated priority") for each frequency specified by the gNB 200, for example, by a system information block (SIB) or an RRC release message. Specifically, the NCR-MT 520A manages the frequency priority specified by the gNB 200 for each frequency.

[0078] In step S12, the NCR-MT520A performs a measurement process to measure the radio quality of each of the serving cell and neighboring cells. The NCR-MT520A measures the received power and received quality of reference signals transmitted by each of the serving cell and neighboring cells, specifically, CD-SSB (Cell Defining-Synchronization Signal and PBCH block). For example, the NCR-MT520A always measures the radio quality of frequencies with a higher priority than the frequency priority of the current serving cell, and for frequencies with a priority equal to or lower than the frequency priority of the current serving cell, if the radio quality of the current serving cell falls below a predetermined quality, measures the radio quality of the frequency with the same priority or lower priority.

[0079] In step S13, the NCR-MT520A performs a cell reselection process to reselect a cell to which it will camp based on the measurement results of step S12. For example, if the frequency priority of a neighboring cell is higher than the priority of the current serving cell and the neighboring cell meets a predetermined quality standard (i.e., a minimum required quality standard) for a predetermined period of time, the NCR-MT520A may perform cell reselection to the neighboring cell. If the frequency priority of a neighboring cell is the same as the priority of the current serving cell, the NCR-MT520A may rank the wireless qualities of the neighboring cells and perform cell reselection to a neighboring cell that has a higher rank than the rank of the current serving cell for a predetermined period of time. If the frequency priority of a neighboring cell is lower than the priority of the current serving cell, the NCR-MT520A may perform cell reselection to the neighboring cell if the wireless quality of the current serving cell is lower than a certain threshold and the wireless quality of the neighboring cell remains higher than another threshold for a predetermined period of time.

[0080] (1.5) Operation according to the first embodiment The first embodiment is an embodiment related to cell reselection of the NCR device 500A (NCR-MT 520A) in the RRC inactive state or the RRC idle state.

[0081] 13 is a diagram for explaining the operation according to the first embodiment. In the illustrated example, first, the NCR device 500A (NCR-MT 520A) is in an RRC connected state in cell a managed by gNB 200a. Cell b adjacent to cell a is managed by gNB 200b, which is different from gNB 200a. However, cells a and b may be managed by the same gNB 200. The NCR device 500A (NCR-MT 520A) is assumed to be performing relay operation in accordance with an NCR control signal received from cell a (gNB 200a) (i.e., NCR-Fwd 510A is on).

[0082] Second, the NCR-MT520A receives an RRC Release message including a suspend setting from cell a (gNB200) and transitions to the RRC inactive state. The NCR-MT520A in the RRC inactive state keeps the NCR-Fwd510A on according to the latest NCR control signal (particularly, the NCR setting information) received from the gNB200. Such an operation may be applied not only to the RRC inactive state but also to the RRC idle state.

[0083] Third, after the NCR-MT520A transitions to the RRC inactive state (or the RRC idle state) in cell a, the NCR-MT520A may reselect another cell b due to, for example, the blocking of FR (Frequency Range) 2. In this case, there is no problem if the NCR-Fwd510A is off, but if the NCR-Fwd510A is on, there is a concern that the latest NCR setting information held by the NCR device 500A was provided by cell a and may not be suitable for cell b.

[0084] It is necessary to clarify how the NCR device 500A operates in such a scenario. There are two possible options:

[0085] Option 1: The NCR-Fwd510A will continue to turn on with the latest NCR configuration information.

[0086] Option 2: NCR-Fwd 510A is turned off. The NCR device 500A may discard the latest NCR configuration information.

[0087] Option 1 is preferable from the viewpoint of simplifying the operation of the NCR-MT 520A. However, since the latest NCR configuration information is provided by cell a (i.e., the last serving cell), it may be problematic for the NCR-Fwd 510A to operate according to the configuration information in another cell b. For example, the reselected cell b may have a different set of resources available to the NCR device 500A. Therefore, from the viewpoint of technical rationality, Option 2 is more preferable.

[0088] In the first embodiment, when the NCR-MT 520A is in an RRC idle state or an RRC inactive state in a first cell (e.g., cell a) and the NCR-Fwd 510A is on, the NCR-MT 520A performs cell reselection to a second cell (e.g., cell b) different from the first cell. The NCR device 500A (NCR-MT 520A) turns off the NCR-Fwd 510A based on the cell reselection from the first cell to the second cell. That is, when the NCR-MT 520A reselects a different cell, the NCR device 500A controls to turn off the NCR-Fwd 510A.

[0089] When the NCR-MT 520A is in an RRC idle state or an RRC inactive state in the first cell, the NCR device 500A (NCR-MT 520A) may hold an NCR control signal (the most recent NCR control signal) received from the first cell. The NCR-MT 520A may discard the most recent NCR control signal (also referred to as an "NCR-Fwd context") that it has held in response to cell reselection from the first cell to the second cell.

[0090] After cell reselection from the first cell to the second cell, the NCR-MT520A may transition to an RRC connected state in the second cell to obtain an NCR control signal from the second cell. For example, the NCR-MT520A in an RRC idle state in the second cell transitions to the RRC connected state through an RRC connection establishment procedure. The NCR-MT520A in an RRC inactive state in the second cell transitions to the RRC connected state through an RRC connection recovery procedure. The NCR-MT520A that has transitioned to the RRC connected state in the second cell receives a new NCR control signal related to relay operation from the second cell. The NCR device 500A then controls the relay operation based on the NCR control signal received from the second cell. Note that, hereinafter, the RRC connection establishment procedure and the RRC connection recovery procedure may be collectively referred to as the "RRC connection procedure."

[0091] FIG. 14 is a diagram showing an example of the operation of the NCR device 500A according to the first embodiment.

[0092] In step S101, NCR-MT520A, which is in the RRC connected state in cell a, receives an NCR control signal from cell a (gNB200) including information indicating that NCR-MT520A is on (NCR setting information or NCR control information), and controls NCR-Fwd510A to be on.

[0093] In step S102, the NCR-MT520A transitions to the RRC idle state or the RRC inactive state. The NCR-MT520A transitions to the RRC idle state or the RRC inactive state by receiving an RRC Release message from cell a (gNB200). The NCR-MT520A holds the latest NCR control signal. For example, the NCR-MT520A holds information indicating that the NCR-MT520A is on (NCR setting information or NCR control information). The NCR device 500A keeps the NCR-Fwd510A on in accordance with the latest NCR control signal.

[0094] In step S103, the NCR-MT 520A in the RRC idle state or the RRC inactive state in the cell a reselects the cell b by cell reselection. The cell b is a cell different from the current cell a and is a cell different from the cell a that performed the latest setting (and control). The cell b may be a cell different from the desired cell to which the NCR device 500A should be connected due to the station placement design (communication service area design).

[0095] In step S104, the NCR-MT 520A controls the NCR-Fwd 510A to be turned off in response to the reselection of cell b. The NCR-MT 520A may discard the latest NCR control signal that it has retained.

[0096] In step S105, in response to the reselection of cell b, NCR-MT520A may initiate an RRC connection procedure (RRC connection establishment procedure or RRC connection recovery procedure) for cell b to transition to the RRC connected state. The RRC connection establishment procedure includes sending an RRC establishment request message from NCR-MT520A to cell b, and sending an RRC establishment message from cell b to NCR-MT520A. The RRC connection recovery procedure includes sending an RRC recovery request message from NCR-MT520A to cell b, and sending an RRC recovery message from cell b to NCR-MT520A. Upon completion of the RRC connection procedure, NCR-MT520A transitions to the RRC connected state.

[0097] The NCR-MT520A may initiate an RRC connection procedure with cell b only if at least one of the following first and second conditions is met.

[0098] First condition: Cell b is a desired cell. In other words, this is a condition that cell b corresponds to one of the predetermined cells, on the premise that one or more cells to which the NCR-MT520A should be connected are determined in the station placement design.

[0099] Second condition: Cell b transmits SIB1 including information indicating that it supports the NCR device (NCR Support IE).

[0100] The NCR-MT 520A that has transitioned to the RRC connected state in the cell b receives a new NCR control signal from the cell b, and controls (for example, turns on) the NCR-Fwd 510A in accordance with the received NCR control signal.

[0101] (1.6) First Modification of the First Embodiment The first modification of the first embodiment will be described, focusing mainly on the differences from the first embodiment described above.

[0102] For example, even if the NCR-MT520A performs cell reselection, if the geographical location of the NCR device 500A does not change, it may be possible that there is no problem if the NCR-Fwd510A continues to operate with the original settings. Therefore, the gNB200 may be able to set whether or not to turn off the NCR-Fwd510A when the NCR device 500A reselects cell b. In this modification, the gNB200, which manages cell a, sets to the NCR-MT520A whether or not to turn off the NCR-Fwd510A upon cell reselection.

[0103] The NCR-MT520A receives setting information (also referred to as "on / off setting information") for specifying whether to turn off the NCR-Fwd510A upon cell reselection from cell a (gNB200). If the on / off setting information indicates that the NCR-Fwd510A should be turned off upon cell reselection, the NCR device 500A turns off the NCR-Fwd510A in response to cell reselection to cell b.

[0104] 15 is a diagram showing an example of the operation of an NCR device 500A according to a first modification of the first embodiment. Here, differences from the first embodiment described above will be mainly described, and overlapping descriptions will be omitted.

[0105] In step S131, the NCR-MT 520A in the RRC connected state in cell a receives an NCR control signal from cell a (gNB 200) and turns on the NCR-Fwd 510A in accordance with the NCR control signal. The NCR control signal may include on / off setting information. Alternatively, the on / off setting information may be broadcast in the SIB in cell a. The NCR-MT 520A receives the on / off setting information. The on / off setting information may include a setting for whether the NCR-Fwd 510A is allowed to operate as a conventional RF repeater (i.e., an RF repeater independent of network control) when kept on. Note that when the NCR device 500A has multiple NCR-Fwds 510A (i.e., the NCR-MT 520A handles multiple NCR-Fwds 510A), the on / off setting information may include information for setting each of the multiple NCR-Fwds 510A to on or off during cell reselection.

[0106] In step S132, the NCR-MT 520A transitions to the RRC idle state or the RRC inactive state. The NCR-Fwd 510A is assumed to be turned on in accordance with the latest NCR control signal. The NCR-MT 520A holds the latest NCR control signal.

[0107] In step S133, the NCR-MT 520A that has transitioned to the RRC idle state or the RRC inactive state in the cell a reselects the cell b by cell reselection.

[0108] In step S134, the NCR-MT 520A determines whether the on / off setting information set by the cell a (gNB 200) indicates that the NCR-Fwd 510A is off. Note that if the NCR device 500A has multiple NCR-Fwd 510A, the NCR-Fwd 510A may perform the determination in step S134 for each of the multiple NCR-Fwd 510A.

[0109] If the on / off setting information indicates that NCR-Fwd 510A is off (step S134: YES), in step S135, NCR-MT 520A controls NCR-Fwd 510A to be off in response to the reselection of cell b. NCR-MT 520A may discard the latest NCR control signal it has retained. The operation of step S136 is the same as in the first embodiment described above.

[0110] If the on / off setting information indicates that the NCR-Fwd 510A is on (step S134: NO), in step S137, the NCR-MT 520A keeps the NCR-Fwd 510A on even when reselecting cell b. The NCR device 500A may operate the NCR-Fwd 510A as a conventional RF repeater.

[0111] (1.7) Second Modification of the First Embodiment The second modified example of the first embodiment will be described, focusing mainly on the differences from the first embodiment described above. This modified example may be implemented in combination with the first modified example described above.

[0112] An effective area in which the same NCR control signal can be used in other cells may be set to the NCR-MT520A from the network 5 (gNB200). The effective area is an area consisting of one or more cells. For example, the gNB200 transmits to the NCR-MT520A an NCR control signal including NCR setting information and / or NCR control information related to relay operation and area information indicating the effective area of ​​the NCR setting information and / or NCR control information. The area information may be a list of cell IDs or (a list of) frequency IDs.

[0113] The area information may be information for identifying the gNB 200, for example, a gNB ID or any ID for identifying the gNB (for example, a part of the gNB ID may be used (shortened), or a number form different from the gNB ID may be used). The identification information may be broadcast by the gNB 200 in an SIB, and the UE 100 may use the broadcast information to determine whether the cell where RRC has been re-established belongs to the effective area.

[0114] In this modification, the NCR-MT 520A receives an NCR control signal from cell a (gNB 200) that includes information indicating that the NCR-Fwd 510A should be turned on and area information indicating the valid area of ​​the information. If cell b does not belong to the valid area, the NCR device 500A turns off the NCR-Fwd 510A in response to cell reselection to cell b. On the other hand, if cell b belongs to the valid area, the NCR device 500A keeps the NCR-Fwd 510A on even when cell reselection to cell b is performed.

[0115] 16 is a diagram showing an example of the operation of an NCR device 500A according to a second modified example of the first embodiment. Here, differences from the first embodiment described above will be mainly described, and overlapping descriptions will be omitted.

[0116] In step S151, the NCR-MT 520A in the RRC connected state in cell a receives an NCR control signal from cell a (gNB 200) and turns on the NCR-Fwd 510A in accordance with the NCR control signal. The NCR control signal includes area information indicating an effective area. The effective area may be set commonly for the NCR setting information and the NCR control information, or may be set separately.

[0117] In step S152, the NCR-MT 520A transitions to the RRC idle state or the RRC inactive state. The NCR-Fwd 510A is assumed to be turned on in accordance with the latest NCR control signal. The NCR-MT 520A holds the latest NCR control signal.

[0118] In step S153, the NCR-MT 520A that has transitioned to the RRC idle state or the RRC inactive state in cell a reselects cell b. The NCR-MT 520A may notify the upper layer that cell b has been reselected.

[0119] In step S154, NCR-MT520A determines whether cell b belongs to the effective area based on the area information set by cell a (gNB200).

[0120] If it is determined that cell b belongs to the valid area (step S154: YES), in step S155, the NCR device 500A (NCR-MT 520A) turns on the NCR-Fwd 510A in accordance with the latest NCR control signal.

[0121] On the other hand, if it is determined that cell b does not belong to the effective area (step S154: NO), in step S156, the NCR device 500A (NCR-MT520A) turns off the NCR-Fwd510A. The NCR-MT520A may discard the NCR control signal it is holding. The NCR-MT520A may notify the upper layer that it does not belong to the effective area (that it has reselected cell b, which does not belong to the effective area). The operation of step S157 is the same as in the first embodiment described above.

[0122] (1.8) Third Modification of the First Embodiment The third modified example of the first embodiment will be described, focusing mainly on the differences from the first embodiment described above. This modified example may be implemented in combination with the modified examples described above.

[0123] The above-mentioned effective area may be determined by negotiation between gNBs 200. For example, the gNB 200 transmits an NCR control signal (NCR setting information) to be set in the NCR device 500A of its own cell to a neighboring gNB. If the neighboring gNB determines that the NCR control signal is applicable to its own cell, it may permit its own cell as an effective area for the NCR control signal.

[0124] For example, the gNB 200b that manages cell b acquires, from the gNB 200a that manages cell a, NCR setting information that the gNB 200a sets in the NCR device 500A. The gNB 200b may transmit to the gNB 200a a notification indicating the result of determining whether the NCR setting information is valid in cell b based on the acquired NCR setting information. If the NCR setting information acquired from the gNB 200a is also valid in cell b, the gNB 200b can omit setting the NCR setting information in the NCR-MT 520A from the gNB 200b.

[0125] For example, when cell b relays the same resources as cell a, or when NCR device 500A located in cell b relays radio signals from cell a, it may be determined that the NCR setting information obtained from gNB 200a is also valid in cell b.

[0126] 17 is a diagram showing an example of the operation of a mobile communication system 1 according to a third modification of the first embodiment. Here, differences from the first embodiment will be mainly described, and overlapping descriptions will be omitted. It is assumed that communication between gNB 200a and gNB 200b is performed, for example, over an Xn interface. It is also assumed that NCR-MT 520A is connected to cell a and controls NCR-Fwd 510A in accordance with an NCR control signal from cell a.

[0127] In step S171, the gNB 200b may inquire of the gNB 200a about the NCR setting information of the NCR device 500A located in the cell a. At this point, the NCR device 500A may not have moved to the cell b yet.

[0128] In step S172, the gNB 200a transmits an Xn message (e.g., a gNB Configuration Update message) including the NCR setting information to the gNB 200b. The NCR setting information may be notified as a combination (e.g., in a list format) of the identifier of the NCR device 500A and the NCR setting information.

[0129] In step S173, the gNB 200b may determine whether the NCR setting information from the gNB 200a can be used in its own cell (cell b) based on the NCR setting information, and notify the gNB 200a of the determination result. Here, the description will proceed assuming that the NCR setting information can be used in cell b.

[0130] The gNB 200a may set an area where the current NCR setting information can continue to be applied to the NCR-MT 520A (see the second modification). Based on this setting, the NCR device 500A controls the NCR-Fwd 510A according to the current NCR setting information even after reselecting the cell b.

[0131] Alternatively, a scenario may be assumed in which the NCR device 500A is handed over from cell a to cell b. When the gNB200a determines the handover, if the gNB200a has already notified the gNB200b of the NCR setting information or if it has confirmed that the NCR setting information can be reused, the gNB200a may not include the NCR setting information in the handover request message to be transmitted to the gNB200b. Furthermore, when determining a target cell for handover, the gNB200a may prioritize another cell that can reuse the NCR setting information as the target cell.

[0132] (2) Second embodiment The second embodiment will be described mainly focusing on the differences from the first embodiment. The first embodiment and its modifications may be combined with the second embodiment.

[0133] The second embodiment has the same basic assumed scenario as the first embodiment, except that, instead of turning off the NCR-Fwd 510A in response to cell reselection as in the first embodiment, the second embodiment turns off the NCR-Fwd 510A in response to the start of an RRC connection procedure.

[0134] That is, in the second embodiment, when the NCR-MT 520A is in the RRC idle state or the RRC inactive state in the first cell and the NCR-Fwd 510A is on, the NCR-MT 520A initiates an RRC connection procedure (an RRC connection establishment procedure or an RRC connection reestablishment procedure) for the second cell to transition to the RRC connected state. The NCR device 500A turns off the NCR-Fwd 510A based on the initiation of the RRC connection procedure. In the second embodiment, the second cell is a target cell for the RRC connection establishment or RRC connection reestablishment.

[0135] However, in the second embodiment, if the second cell is the same cell as the first cell, the NCR device 500A may start the RRC connection procedure or keep the NCR-Fwd 510A on.

[0136] 18 is a diagram for explaining an example of operation according to the second embodiment. The following mainly describes operation when the NCR-MT520A is in the RRC inactive state rather than the RRC idle state. However, in the following description, the RRC inactive state may be read as the RRC idle state, and the RRC connection recovery may be read as the RRC connection establishment.

[0137] First, the NCR device 500A (NCR-MT520A) is in an RRC connected state in cell a managed by gNB200a. Cell b adjacent to cell a is managed by gNB200b, which is different from gNB200a. However, cells a and b may be managed by the same gNB200. The NCR device 500A (NCR-MT520A) is assumed to be performing relay operation in accordance with an NCR control signal received from cell a (gNB200a) (i.e., NCR-Fwd510A is on).

[0138] Second, the NCR-MT520A receives an RRC Release message including a suspend setting from cell a (gNB200) and transitions to the RRC inactive state. The NCR-MT520A in the RRC inactive state keeps the NCR-Fwd510A on according to the latest NCR control signal (particularly, the NCR setting information) received from the gNB200.

[0139] Third, after the NCR-MT 520A transitions to the RRC inactive state in cell a, the NCR-MT 520A reselects another cell b, for example, due to blocking of FR2. In the second embodiment, the NCR device 500A does not turn off the NCR-Fwd 510A but keeps it on at the time of cell reselection. However, the NCR device 500A may operate the NCR-Fwd 510A as a conventional RF repeater.

[0140] Fourth, the NCR-MT 520A, which has reselected cell b in the RRC inactive state, initiates an RRC connection restoration procedure with cell b. The NCR device 500A turns off the NCR-Fwd 510A based on the initiation of the RRC connection restoration procedure. The NCR-MT 520A, which has transitioned to the RRC connected state in cell b, receives a new NCR control signal from cell b and controls (for example, turns on) the NCR-Fwd 510A in accordance with the received new NCR control signal.

[0141] 19 is a diagram for explaining another example of the operation according to the second embodiment. In the illustrated example, it is assumed that the NCR-MT 520A restores the RRC connection with the original cell a without performing cell reselection.

[0142] First, the NCR device 500A (NCR-MT 520A) is in an RRC connected state in cell a managed by the gNB 200a. The NCR device 500A (NCR-MT 520A) is performing relay operation in accordance with an NCR control signal received from cell a (gNB 200a) (i.e., the NCR-Fwd 510A is on).

[0143] Second, the NCR-MT 520A receives an RRC Release message including a suspend setting from cell a (gNB 200) and transitions to the RRC inactive state. When the NCR-MT 520A is in the RRC inactive state, the NCR device 500A keeps the NCR-Fwd 510A on according to the latest NCR control signal (particularly, the NCR setting information) received from the gNB 200.

[0144] Third, the NCR-MT 520A in the RRC inactive state starts an RRC connection restoration procedure with cell a. In this case, the NCR device 500A keeps the NCR-Fwd 510A on even when starting the RRC connection restoration procedure.

[0145] 20 is a diagram showing an example of the operation of an NCR device 500A according to the second embodiment. Here, differences from the first embodiment will be mainly described, and overlapping descriptions will be omitted.

[0146] In step S201, NCR-MT520A, which is in the RRC connected state in the first cell, receives an NCR control signal from the first cell (gNB200) including information indicating that NCR-MT520A is on (NCR setting information or NCR control information), and controls NCR-Fwd510A to be on.

[0147] In step S202, the NCR-MT 520A transitions to the RRC inactive state. The NCR-MT 520A holds the latest NCR control signal. For example, the NCR-MT 520A holds information indicating that the NCR-MT 520A is on (NCR setting information or NCR control information). The NCR device 500A keeps the NCR-Fwd 510A on in accordance with the latest NCR control signal.

[0148] The NCR-MT 520A in the RRC idle state or the RRC inactive state in the first cell may reselect a cell different from the first cell as the second cell, or the NCR-MT 520A may maintain the same cell as the first cell as the second cell without performing cell reselection.

[0149] In step S203, the NCR-MT 520A initiates an RRC connection recovery procedure for the second cell, for example, by sending an RRC recovery request procedure to the second cell.

[0150] In addition, the NCR-MT520A may start the RRC connection procedure for the second cell only when at least one of the following first and second conditions is satisfied.

[0151] First condition: The second cell is a desired cell. In other words, this condition is based on the premise that one or more cells to which the NCR-MT520A should be connected are determined in the station placement design, and the second cell corresponds to the predetermined cell.

[0152] Second condition: The second cell transmits an SIB1 including information indicating that it supports an NCR device (NCR Support IE).

[0153] In step S204, the NCR-MT520A determines whether the second cell is the same as the first cell. The case where the second cell is different from the first cell corresponds to the case in Figure 19. On the other hand, the case where the second cell is the same as the first cell corresponds to the case in Figure 20.

[0154] If it is determined that the second cell is a cell different from the first cell (step S204: NO), in step S205, the NCR device 500A (NCR-MT 520A) controls the NCR-Fwd 510A to be turned off in response to the start of the RRC connection recovery procedure. The NCR-MT 520A may discard the latest NCR control signal it has retained. In this case, after transitioning to the RRC connected state in the second cell, the NCR-MT 520A may receive a new NCR control signal from the second cell and control (for example, turn on) the NCR-Fwd 510A in accordance with the received NCR control signal.

[0155] On the other hand, if it is determined that the second cell is the same cell as the first cell (step S204: YES), in step S206, the NCR device 500A (NCR-MT520A) keeps the NCR-Fwd510A on according to the latest NCR control signal it holds, even if it starts the RRC connection recovery procedure.

[0156] In this operation example, the operation when the NCR-MT520A transitions from the RRC inactive state to the RRC connected state has been described, but the operation when the NCR-MT520A transitions from the RRC idle state to the RRC connected state may be the same as the operation in FIG. 20 . Alternatively, the operation when the NCR-MT520A transitions from the RRC idle state to the RRC connected state may be partially different from the operation in FIG. 20 . When the NCR-MT520A is in the RRC idle state, the gNB200 may not have the context of the NCR device 500A, and there is a concern that continuing the on control may not be desirable. Therefore, as shown in FIG. 21 , when the NCR-MT520A transitions from the RRC idle state to the RRC connected state, the NCR device 500A may uniformly turn off the NCR-Fwd510A upon initiation of the RRC connection establishment procedure, regardless of whether the cell is the same or not.

[0157] Moreover, the second embodiment can be applied to each of the modifications of the first embodiment described above.

[0158] For example, similar to the first modification of the first embodiment, the NCR control signal may include on / off setting information indicating whether the NCR-Fwd 510A should be turned off when the RRC connection is restored. Alternatively, the on / off setting information may be broadcast in the SIB in cell a. The NCR-MT 520A receives the on / off setting information. The on / off setting information may include a setting indicating whether the NCR-Fwd 510A should operate as a conventional RF repeater (i.e., an RF repeater independent of network control) when it is kept on. Note that, in a case where the NCR device 500A has multiple NCR-Fwds 510A (i.e., the NCR-MT 520A handles multiple NCR-Fwds 510A), the on / off setting information may include information for setting each of the multiple NCR-Fwds 510A to on or off when the RRC connection is restored. For example, the NCR-MT 520A may receive on / off setting information from cell a for specifying whether to turn off the NCR-Fwd 510A during the RRC connection recovery procedure. If the on / off setting information indicates that the NCR-Fwd 510A is to be turned off during the RRC connection recovery procedure, the NCR device 500A may turn off the NCR-Fwd 510A in response to the start of the RRC connection recovery procedure. Note that the on / off setting information may be broadcast by the SIB from cell b (gNB 200b).

[0159] As in the second modification of the first embodiment, the NCR control signal may include setting information indicating that the NCR-Fwd 510A is to be turned on and area information indicating the valid area of ​​the setting information. If the cell b does not belong to the valid area, the NCR device 500A may turn off the NCR-Fwd 510A in response to the start of the RRC connection recovery procedure. If the cell b belongs to the valid area, the NCR device 500A may keep the NCR-Fwd 510A on even when the RRC connection recovery procedure is started.

[0160] As in the third modification of the first embodiment, the gNB 200b that manages the cell b may obtain, from the gNB 200a that manages the cell a, the configuration information that the gNB 200a configures in the NCR device 500A.

[0161] (3) Third embodiment Next, a third embodiment will be described, focusing on differences from the above-described embodiments. As shown in Fig. 22, the repeater according to the third 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. "NCR" in the above-described embodiments can be read as "RIS."

[0162] 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 metamaterials. In the case of RIS, the range (distance) of the beam may also be changeable by controlling the reflection direction and / or refraction direction of each unit element. For example, the RIS may be configured to be able 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.

[0163] 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 waves is variably settable.

[0164] FIG. 23 is a diagram showing an example configuration of a RIS-Fwd (repeater) 510B and a RIS-MT (control terminal) 520B according to the third embodiment. The RIS-MT 520B includes a receiver 521, a transmitter 522, and a controller 523. 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 made of metamaterial. For example, the RIS 511B is configured by arranging structures that are very small compared to the wavelength of radio waves in an array. By making the structures different shapes depending on their placement, it is possible to arbitrarily design the direction and / or beam shape of the reflected waves. The RIS 511B may be a transparent dynamic metasurface. The RIS511B 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. 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 RIS511B in response to a RIS control signal from the control unit 523 of the RIS-MT520B. The RIS control unit 512B may include at least one processor and at least one actuator. The processor decodes the RIS control signal from the control unit 523 of the RIS-MT520B and drives the actuator in response to the RIS control signal.

[0165] (4) Other embodiments In the above-described first embodiment, an example has been described in which the NCR-MT 520A in the RRC inactive state or the RRC idle state performs cell reselection. In the above-described second embodiment, an example has been described in which the NCR-MT 520A in the RRC inactive state or the RRC idle state performs an RRC connection procedure (RRC connection recovery procedure or RRC connection establishment procedure). However, the operations according to the above-described embodiments and their modifications may be applied to handover performed by the NCR-MT 520A in the RRC connected state. For example, the cell reselection in the above-described first embodiment may be read as handover. The RRC connection procedure (RRC connection recovery procedure or RRC connection establishment procedure) in the above-described second embodiment may be read as handover.

[0166] 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.

[0167] 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.

[0168] In the above-described 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). Also, the base station may be a relay node such as an IAB node. Also, the base station may be a DU (Distributed Unit) of the IAB node. Also, the UE 100 may be an MT (Mobile Termination) of the IAB node.

[0169] Furthermore, the term "network node" primarily refers to a base station, but may also refer to a core network device or part of a base station (CU, DU, or RU). A network node may also be configured by a combination of at least part of a core network device and at least part of a base station.

[0170] A program may be provided that causes a computer to execute each process performed by a communication device according to the above-described embodiments, for example, the UE100 (NCR-MT520A, RIS-MT520B), the gNB200, or the relay device. The program may be recorded on a computer-readable medium. The computer-readable medium can be used to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by the UE100, the gNB200, or the relay device may be integrated, and at least a part of the UE100, the gNB200, or the relay device may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0171] The functions performed by the UE 100, gNB 200 (network node), or 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 (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 a memory. In this specification, a circuit, unit, or means is hardware that is programmed to perform or executes the described functions. The hardware may be any hardware disclosed in this specification or any hardware known to be programmed to perform or execute the described functions. When the hardware is a processor, which is considered to be a type of circuitry, the circuit, means, or unit is a combination of hardware and software used to configure the hardware and / or processor.

[0172] 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.

[0173] 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.

[0174] This application claims priority from Japanese Patent Application No. 2023-019937 (filed February 13, 2023), the entire contents of which are incorporated herein by reference.

[0175] (5) Supplementary notes The following additional notes are about the features of the above-described embodiment.

[0176] (Appendix 1) A communication method using 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, When the control terminal is in a radio resource control (RRC) idle state or an RRC inactive state in a first cell and the relay is on, the control terminal initiates a procedure for transitioning to an RRC connected state for a second cell; the relay device turning off the relay upon initiation of the procedure. Communication method.

[0177] (Appendix 2) the initiating step includes a step of the control terminal in the RRC inactive state initiating an RRC connection reestablishment procedure as the procedure; The step of turning off includes turning off the relay based on initiation of the RRC connection reestablishment procedure. 1. A communication method as described in Appendix 1.

[0178] (Appendix 3) The step of turning off includes turning off the repeater in response to initiation of the procedure if the second cell is a different cell than the first cell. 3. A communication method according to claim 1 or 2.

[0179] (Appendix 4) If the second cell is the same cell as the first cell, then starting the procedure and keeping the repeater on. 4. A communication method according to any one of claims 1 to 3.

[0180] (Appendix 5) The control terminal further comprises receiving configuration information from the first cell for specifying whether to turn off the repeater during the procedure; The step of turning off includes turning off the repeater in response to initiation of the procedure if the configuration information indicates that the repeater is to be turned off during the procedure. 5. A communication method according to any one of claims 1 to 4.

[0181] (Appendix 6) the control signal includes setting information indicating that the repeater is to be turned on and area information indicating an area in which the setting information is valid; The step of turning off includes turning off the repeater in response to initiation of the procedure if the second cell does not belong to the coverage area. 6. A communication method according to any one of appendices 1 to 5.

[0182] (Appendix 7) The method further includes a step in which a second network node that manages the second cell acquires, from a first network node that manages the first cell, configuration information that the first network node configures in the relay device. 7. A communication method according to any one of appendices 1 to 6.

[0183] (Appendix 8) a repeater that performs a relay operation of relaying a wireless signal transmitted between a network and a user device; a control terminal that receives a control signal used to control the repeater from the network; The control terminal Initiating a procedure for transitioning to a radio resource control (RRC) connected state for a second cell when the first cell is in a radio resource control (RRC) idle state or an RRC inactive state and the relay is on; Upon initiation of the procedure, the repeater is turned off. Relay device. [Explanation of symbols]

[0184] 1: Mobile communication system 100:UE 200:gNB 210: Transmitter 220: Receiving unit 230: Control unit 240: Backhaul communication unit 500A:NCR device 510A:NCR-Fwd 520A:NCR-MT 500B:RIS device 510B:RIS-Fwd 520B:RIS-MT 511A: Wireless unit 511a: Antenna section 511b:RF circuit 511c: Directivity control unit 512A: NCR control unit 512B: RIS control unit 521: Receiving unit 522: Transmitter 523: Control unit 530: Interface

Claims

1. a repeater device configured to perform a forwarding operation of radio signals transmitted between a network and a user equipment; and a control terminal supporting the functions of the user equipment; 1. A method of communication using a repeater node having causing the repeater device to continue the forwarding operation when the control terminal transitions from a Radio Resource Control (RRC) connected state to an RRC inactive state; Initiating a procedure for restoring the control terminal to an RRC connected state when the control terminal is in an RRC inactive state; the control terminal receiving, in the procedure, a message from the network regarding the stopping of the forwarding operation; When the control terminal receives the message, the control terminal causes the repeater device to stop the forwarding operation. Communication method.

2. The method further includes the control terminal turning off the repeater device when the control terminal in the RRC inactive state in the first cell selects a second cell different from the first cell in a predetermined procedure. The communication method according to claim 1 .

3. A repeater node comprising: a repeater device configured to perform a forwarding operation of radio signals transmitted between a network and a user equipment; and a control terminal supporting the functions of the user equipment, the control terminal has a control unit and a receiving unit, The control unit causing the repeater device to continue the forwarding operation when transitioning from a Radio Resource Control (RRC) connected state to an RRC inactive state; Initiating a procedure to restore an RRC connected state when in an RRC inactive state; When the receiving unit receives a message regarding the stop of the forwarding operation, the receiving unit causes the repeater device to stop the forwarding operation; The receiving unit In the procedure, the message is received from the network. Repeater node.

4. a repeater node including a repeater device configured to perform a forwarding operation of a radio signal transmitted between a network and a user device, and a control terminal supporting the functions of the user device; A process of causing the repeater device to continue the forwarding operation when transitioning from a Radio Resource Control (RRC) connected state to an RRC inactive state; Initiating a procedure for recovering to an RRC connected state when in an RRC inactive state; receiving a message from the network regarding the stop of the forwarding operation; When the message is received, the repeater device stops the forwarding operation. program.

5. A chipset for a repeater node, comprising: a repeater device configured to perform forwarding operations of radio signals transmitted between a network and a user equipment; and a control terminal supporting the functions of said user equipment, A process of causing the repeater device to continue the forwarding operation when transitioning from a Radio Resource Control (RRC) connected state to an RRC inactive state; Initiating a procedure for recovering to an RRC connected state when in an RRC inactive state; receiving a message from the network regarding the stop of the forwarding operation; When the message is received, the repeater device stops the forwarding operation. Chipset.

6. A system including a network, a user equipment, and a repeater node, The repeater node comprises a repeater device configured to perform a forwarding operation of radio signals transmitted between the network and the user equipment, and a control terminal supporting the functions of the user equipment; the control terminal has a control unit and a receiving unit, The control unit causing the repeater device to continue the forwarding operation when transitioning from a Radio Resource Control (RRC) connected state to an RRC inactive state; Initiating a procedure to restore an RRC connected state when in an RRC inactive state; When the receiving unit receives a message regarding the stop of the forwarding operation, the receiving unit causes the repeater device to stop the forwarding operation; The receiving unit In the procedure, the message is received from the network. system.

7. A user equipment controlling a repeater device configured to perform a forwarding operation of a radio signal transmitted between a network and the user equipment, The user device has a control unit and a receiving unit, The control unit When transitioning from a radio resource control (RRC) connected state to an RRC inactive state, continuing a forwarding operation by the repeater device; Initiating a procedure to restore an RRC connected state when in an RRC inactive state; When the receiving unit receives a message regarding the stop of the forwarding operation, the repeater device stops the forwarding operation; The receiving unit In the procedure, the message is received from the network. User equipment.

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