Communication method, relay device, mobile communication system, program, and chipset

Abstract

Provided is a communication method which is carried out by a relay device comprising a relay that carries out a relay operation for relaying a radio signal transmitted between a base station and a user device, and a control terminal that receives, from the base station, a control signal for use in control of the relay, said method comprising: a step for receiving, from a first cell, setting information pertaining to the relay operation; a step for using the setting information to carry out the relay operation when the control terminal is in a radio resource control (RRC) inactive state in the first cell; a step for stopping the relay operation when cell re-selection from the first cell to a second cell is carried out; and a step for re-starting the relay operation using the setting information when cell re-selection to the first cell is carried out within a prescribed time after the cell re-selection to the second cell has been carried out.

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 very straight line, which can lead to a reduction in 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 attracted attention (see, for example, Non-Patent Document 1).

[0004] Such a repeater device can extend the coverage of a base station while suppressing interference by amplifying a radio signal received from the base station and transmitting the signal in a directional manner. Such a repeater device is also called an NCR (Network-Controlled Repeater). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP contribution: RP-213700, “New SI: Study on NR Network-controlled Repeaters” Summary of the Invention

[0006] A communication method according to a first aspect is a communication method executed by a relay device having a relay device that performs a relay operation to relay radio signals transmitted between a base station and a user device, and a control terminal that receives a control signal used to control the relay device from the base station, and includes the steps of receiving configuration information related to the relay operation from a first cell, performing the relay operation using the configuration information when the control terminal is in a radio resource control (RRC) inactive state in the first cell, stopping the relay operation when cell reselection from the first cell to a second cell is performed, and resuming the relay operation using the configuration information when cell reselection to the first cell is performed within a predetermined time after cell reselection to the second cell.

[0007] A relay device according to a second aspect includes a relay that performs a relay operation to relay radio signals transmitted between a base station and a user device, and a control terminal that receives a control signal from the base station to control the relay, wherein the control terminal includes a receiving unit that receives configuration information related to the relay operation from a first cell, and a control unit that controls the relay to perform the relay operation using the configuration information when the control terminal is in a radio resource control (RRC) inactive state in the first cell, and the control unit stops the relay operation when cell reselection from the first cell to a second cell is performed, and resumes the relay operation using the configuration information when cell reselection to the first cell is performed within a predetermined time after the cell reselection to the second cell.

[0008] A communication method according to a third aspect is a communication method executed by a relay device having a relay device that performs relaying operations to relay radio signals transmitted between a base station and a user device, and a control terminal that receives a control signal from the base station used to control the relay device, and includes the steps of receiving first setting information regarding the relaying operation from the base station, receiving second setting information from the base station regarding whether the control terminal will perform a beam failure detection process with the base station when the control terminal is in a radio resource control (RRC) inactive state, and controlling the relaying operation based on the first setting information and controlling the detection process based on the second setting information when the control terminal is in the RRC inactive state.

[0009] A relay device according to a fourth aspect comprises a relay that performs relaying operations to relay radio signals transmitted between a base station and a user device, and a control terminal that receives a control signal from the base station used to control the relay, wherein the control terminal includes a receiving unit that receives first setting information regarding the relaying operation from the base station and receives second setting information from the base station regarding whether the control terminal will perform a beam failure detection process with the base station when the control terminal is in a radio resource control (RRC) inactive state, and a control unit that controls the relaying operation based on the first setting information and controls the detection process based on the second setting information when the control terminal is in the RRC inactive state. [Brief explanation of the drawings]

[0010] [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] FIG. 2 is a diagram for explaining an example of the configuration of a protocol stack in the NCR device according to the embodiment. [Figure 8] FIG. 1 is a diagram illustrating an example of the configuration of an NCR device according to an embodiment. [Figure 9] 1 is a diagram illustrating a configuration of a UE (user equipment) according to an embodiment. [Figure 10] A diagram showing an example configuration of a gNB (base station) according to an embodiment. [Figure 11] FIG. 2 is a diagram for explaining the operation of the mobile communication system according to the first embodiment. [Figure 12] FIG. 2 is a diagram for explaining the operation of the mobile communication system according to the first embodiment. [Figure 13] FIG. 3 is a flowchart showing an example of the operation of the NCR device according to the first embodiment. [Figure 14] FIG. 10 is a diagram for explaining the operation of the mobile communication system according to the second embodiment. [Figure 15] FIG. 10 is a flowchart showing an example of the operation of the NCR device according to the second embodiment. [Figure 16] FIG. 10 is a diagram for explaining a RIS device (relay device) according to the third embodiment. [Figure 17] FIG. 10 is a diagram for explaining a RIS device (relay device) according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0012] (1) First embodiment First, a description will be given of 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.

[0013] (1.1) Overview of mobile communication systems FIG. 1 is a diagram showing a configuration of a mobile communication system according to an embodiment.

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

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

[0016] The UE 100 is a mobile wireless communication device. The UE 100 may be any device 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).

[0017] The NG-RAN 10 includes a base station (referred to as "gNB" in the 5G system) 200. The gNBs 200 are connected to each other via an Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with 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").

[0018] 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.

[0019] 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.

[0020] 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.

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

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

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

[0024] 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.

[0025] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of 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.

[0026] 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.

[0027] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0028] 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.

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

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

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

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

[0033] (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.

[0034] 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.

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

[0036] For example, the NCR device 500A amplifies a radio signal (radio wave) received from the gNB 200 and transmits it by directional transmission. Specifically, the NCR device 500A receives a radio signal transmitted by the gNB 200 by beamforming. The NCR device 500A then amplifies the received radio signal without demodulating or modulating it, and transmits the amplified radio signal by directional transmission. Here, the NCR device 500A may transmit 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.

[0037] 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 performing radio communication with the gNB 200.

[0038] In this way, the NCR-MT520A establishes a wireless connection with the gNB200 and performs wireless communication with the gNB200, thereby controlling the NCR device 500A in cooperation with the gNB200. This enables efficient coverage expansion using the NCR device 500A. The NCR-MT520A controls the NCR device 500A according to control from the gNB200. The NCR-MT520A also has functions similar to those of the UE100.

[0039] 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.

[0040] 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).

[0041] 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.

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

[0043] The NCR-Fwd510A relays radio signals (also referred to as "UE signals") between the gNB200 and the UE100. The UE signals include uplink signals (also referred to as "UE-UL signals") transmitted from the UE100 to the gNB200 and downlink signals (also referred to as "UE-DL signals") transmitted from the gNB200 to the UE100. The NCR-Fwd510A relays UE-UL signals from the UE100 to the gNB200, and relays UE-DL signals from the gNB200 to the UE100. The radio link between the NCR-Fwd510A and the UE100 is also referred to as an "access link." The radio link between the NCR-Fwd510A and the gNB200 is also referred to as a "backhaul link."

[0044] 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."

[0045] The gNB200 directs a beam to the NCR-MT520A based on the NCR-MT-UL signal from the NCR-MT520A. Because the NCR device 500A is co-located with the NCR-MT520A, if the backhaul link and the control link have the same frequency, when the gNB200 directs a beam to the NCR-MT520A, the beam 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.

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

[0047] The NCR-Fwd510A relays wireless signals transmitted and received between the gNB 200 and the UE 100. The NCR-Fwd510A has an RF (Radio Frequency) function that amplifies and relays received wireless signals, and performs directional transmission using beamforming (for example, analog beamforming).

[0048] The NCR-MT520A has entities for each of the layers: Layer 1 and / or Layer 2 (L1 / L2), RRC, and NAS. The L1 / L2 (especially PHY and MAC) and RRC of the NCR-MT520A are also referred to as the "AS of the NCR-MT520A."

[0049] The NCR-MT520A may have at least one of an OAM client that communicates with the OAM (Operation, Administration, Maintenance) server 400, a NAS layer that communicates with the AMF 300A, and an F1-AP (Application Protocol) layer. The OAM client, NAS layer, and F1-AP layer of the NCR-MT520A are also referred to as the "upper layers of the NCR-MT520A" based on the AS of the NCR-MT520A.

[0050] 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.

[0051] In addition, a control link is established between the gNB200 and the L1 / L2 of the NCR-MT520A. The L1 / L2 of the NCR-MT520A transmits and receives L1 / L2 signaling to and from 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 to and from 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.

[0052] 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.

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

[0054] On the other hand, an NCR control signal transmitted in L1 / L2 signaling, i.e., DCI (and / or MAC CE), and used for dynamic control of the NCR-Fwd 510A is also referred to as "NCR control information" or simply "control information." The NCR control information may also be referred to as "Side Control Information." The CRC 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.

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

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] (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.

[0066] (1.3.1) Example of relay device configuration 8 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.

[0067] 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.

[0068] 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.

[0069] 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).

[0070] 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.

[0071] (1.3.2) Example of user device configuration 9 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] (1.3.3) Example of base station configuration 10 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] (1.4) Operation according to the first embodiment 11 and 12 are diagrams for explaining the operation of the mobile communication system 1 according to the first embodiment.

[0081] 11, the NCR device 500A is in an RRC connected state in cell a (first cell) of the gNB 200a. The gNB 200a transmits an RRC Reconfiguration message including the NCR setting to the NCR device 500A. The NCR device 500A receives the RRC Reconfiguration message including the NCR setting from the gNB 200a (cell a) and performs relay operation using the NCR setting.

[0082] In this embodiment, the NCR configuration includes a periodic beam indication. In the periodic beam indication, the periodic configuration and the beam configuration are performed by the RRC. The NCR device 500A performs periodic beamforming based on the periodic beam indication.

[0083] 11, the gNB 200a transmits an RRC Release message including a suspend setting to the NCR device 500A. The NCR device 500A receives the RRC Release message from the gNB 200a (cell a) and transitions to the RRC inactive state.

[0084] In this embodiment, the RRC Release message for transitioning the NCR-MT 520A from the RRC connected state to the RRC inactive state includes a timer value.

[0085] After the NCR-MT520A transitions to the RRC inactive state, the NCR-MT520A controls the NCR-Fwd510A according to the latest (last) NCR setting. In this embodiment, the NCR-MT520A controls the NCR-Fwd510A to continue periodic beamforming operation according to the NCR setting (latest setting) received in STEP 1.

[0086] 12, the NCR-MT520A in the RRC inactive state performs cell reselection from cell a (first cell) to cell b (second cell). In response to the cell reselection to cell b (second cell), the NCR-MT520A turns off the NCR-Fwd510A (i.e., stops relay operation).

[0087] In this embodiment, the NCR-MT520A starts a timer to which the above timer value is set in response to cell reselection from cell a to cell b. At least while the timer is running, the NCR-MT520A retains the NCR settings (latest settings) without discarding them, even if the NCR-Fwd510A is off.

[0088] In the illustrated example, cell b is managed by a gNB 200b that is different from the gNB 200a that manages cell a. However, cell a and cell b may be managed by the same gNB 200.

[0089] As shown in STEP 4 of Fig. 12, if the NCR-MT520A reselects to cell a within a predetermined time after reselecting to cell b, it resumes relay operation using the NCR setting (latest setting). Specifically, if the NCR-MT520A reselects to cell a before the timer expires, it resumes periodic beamforming using the NCR setting (latest setting).

[0090] In this way, if the NCR-MT520A in the RRC inactive state reselects the original cell within a predetermined period after reselecting another cell, it restores (turns on) the operation of the NCR-Fwd510A according to the latest settings. On the other hand, if the NCR-MT520A in the RRC inactive state reselects the original cell after a predetermined period has elapsed after reselecting another cell, it continues to turn off the NCR-Fwd510A.

[0091] This allows the NCR-MT520A to autonomously resume relaying operations when it returns to the original cell after temporarily camping on another cell, thereby enabling efficient control of relaying operations.

[0092] FIG. 13 is a flowchart showing an example of the operation of the NCR device 500A according to the first embodiment.

[0093] In step S11, the NCR-MT 520A in the RRC connected state receives an NCR configuration from the gNB 200. The NCR configuration includes a periodic beam indication. The NCR-MT 520A may store the cell ID of the serving cell (cell a) when the NCR configuration is performed.

[0094] In step S12, the NCR-MT520A in the RRC connected state performs relay operation with periodic beamforming using the NCR setting received in step S11.

[0095] In step S13, the NCR-MT 520A in the RRC connected state receives an RRC Release message including a timer value from the gNB 200. The RRC Release message includes a suspend setting, and the NCR-MT 520A transitions to the RRC inactive state in response to the suspend setting.

[0096] In step S14, the NCR-MT 520A in the RRC inactive state continues the relay operation with periodic beamforming using the NCR setting received in step S11.

[0097] In step S15, NCR-MT520A in the RRC inactive state performs cell reselection to another cell (cell b). In response to cell reselection to another cell (cell b), NCR-MT520A in the RRC inactive state turns off NCR-Fwd510A and starts the timer set to the timer value received in step S13.

[0098] In step S16, the NCR-MT520A determines whether to reselect the original cell (cell a) where the NCR setting was performed. The NCR-MT520A may identify the original cell by comparing the cell ID stored therein with the cell ID of the reselected cell.

[0099] If cell reselection to the original cell (cell a) is performed (step S16: YES), in step S17, the NCR-MT520A determines whether the timer started in step S15 is still running (has not yet expired). If it is determined that the timer has expired (step S17: NO), the NCR-MT520A keeps the NCR-Fwd510A off. When the timer expires, the NCR-MT520A may discard the NCR settings (latest settings) that it has retained.

[0100] On the other hand, if it is determined that the timer is running (step S17: YES), in step S18, NCR-MT520A turns on NCR-Fwd510A and resumes relay operation with periodic beamforming using the NCR settings (latest settings).

[0101] (2) Second embodiment The second embodiment will be described mainly focusing on the differences from the first embodiment. The second embodiment is an embodiment related to beam fault detection and recovery performed by the NCR-MT520A. Note that the second embodiment may be implemented separately from the first embodiment. The second embodiment may also be implemented in combination with the first embodiment.

[0102] (2.1) Overview of beam fault detection and recovery An overview of general beam failure detection and recovery will be described. General beam failure detection (also referred to as "BFD") and beam failure recovery (also referred to as "BFR") are performed by UE 100 in the RRC connected state. For beam failure detection, gNB 200 configures UE 100 with SSB or CSI (Channel State Information)-RS as a reference signal (RS) for BFD. The MAC entity of UE 100 in the RRC connected state declares (detects) beam failure when the number of beam failure instance indicators from the physical layer reaches a threshold (maximum count value) configured by gNB 200 before a timer configured by gNB 200 expires.

[0103] After a beam failure is detected in the primary cell (PCell), the MAC entity of the UE 100 does the following: - triggering a BFR by initiating a random access procedure on the PCell; -Selecting an appropriate beam to perform BFR (if the gNB200 provides dedicated random access resources for a specific beam, it is prioritized by the UE100); -If the random access procedure includes contention-based random access, include an indicator of beam failure on the PCell in the Beam Failure Recovery (BFR) MAC Control Element (CE).

[0104] When the random access procedure is completed, the UE 100 considers that the BFR of the PCell is completed.

[0105] On the other hand, as described above, even if the NCR-MT520A transitions from the RRC connected state to the RRC inactive state, the NCR device 500A can continue relaying according to the latest NCR setting. Therefore, it is desirable that the NCR-MT520A be able to perform BFD and BFR even in the RRC inactive state. For example, when the NCR-MT520A is in the RRC inactive state and the NCR-Fwd510A is on, the NCR device 500A may turn off the NCR-Fwd510A in response to detecting a beam interference with the gNB200.

[0106] In the following second embodiment, an operation that enables the NCR-MT 520A in the RRC inactive state to appropriately control BFD and BFR will be described.

[0107] (2.2) Operation according to the second embodiment FIG. 14 is a diagram for explaining the operation of the mobile communication system 1 according to the second embodiment.

[0108] As shown in STEP 1 of FIG. 14, the NCR device 500A is in an RRC connected state in the cell of the gNB 200. The gNB 200 transmits an RRC Reconfiguration message including the NCR configuration to the NCR device 500A. The NCR device 500A receives the RRC Reconfiguration message including the NCR configuration from the gNB 200 and performs relay operation using the NCR configuration. The NCR configuration may include a periodic beam indication. That is, the NCR configuration includes information for setting relay operation with periodic beamforming, and the NCR-Fwd 510A is set to on. Such configuration information is an example of first configuration information related to relay operation. The NCR-MT 520A receives the first configuration information related to relay operation from the gNB 200.

[0109] 14, the gNB 200 transmits an RRC Release message including a suspend setting to the NCR device 500A. The NCR device 500A receives the RRC Release message from the gNB 200 and transitions to the RRC inactive state.

[0110] In this embodiment, the RRC Reconfiguration message transmitted from the gNB200 to the NCR-MT520A in STEP 1, or the RRC Release message transmitted from the gNB200 to the NCR-MT520A in STEP 2, includes second setting information regarding whether or not the NCR-MT520A will perform beam fault detection processing (BFD) with the gNB200 in the RRC inactive state. That is, the NCR-MT520A receives, from the gNB200, the second setting information regarding whether or not the NCR-MT520A will perform beam fault detection processing with the gNB200 in the RRC inactive state.

[0111] However, instead of providing the second configuration information to the NCR-MT 520A by such dedicated signaling, the gNB 200 may provide the second configuration information to the NCR-MT 520A by broadcast signaling. For example, the gNB 200 may transmit a system information block (SIB) including the second configuration information to the UE 100.

[0112] 14, after the NCR-MT 520A transitions to the RRC inactive state, the NCR-MT 520A controls the NCR-Fwd 510A in accordance with the latest NCR setting. 、R The NCR-MT 520A in the RC inactive state controls the relay operation (NCR-Fwd 510A) based on the first setting information, and also controls the BFD (and BFR) based on the second setting information.

[0113] As described above, in this embodiment, the NCR-MT520A receives second setting information from the gNB200 regarding whether or not to perform beam interference detection processing with the gNB200 in the RRC inactive state. The NCR-MT520A in the RRC inactive state controls BFD (and BFR) based on the second setting information. This enables appropriate control of BFD (and BFR) performed by the NCR-MT520A in the RRC inactive state.

[0114] The basic BFD operation performed by the NCR-MT520A in the RRC inactive state may be an operation that applies general BFD. The MAC entity of the NCR-MT520A may perform BFD in the RRC inactive state by continuing to use the reference signal (RS), timer value, and maximum count value for BFD set by the gNB200 in the RRC connected state. Specifically, the MAC entity of the NCR-MT520A in the RRC inactive state declares (detects) a beam failure when the number of beam failure instance indicators from the physical layer reaches a threshold (maximum count value) set by the gNB200 before the timer set by the gNB200 expires.

[0115] Alternatively, at least one of the reference signal (RS), timer value, and maximum count value for the RRC inactive state may be a parameter independent of the reference signal (RS), timer value, and maximum count value for the RRC connected state. The second configuration information may include information for setting at least one of the reference signal (RS), timer value, and maximum count value for the RRC inactive state. When the second configuration information includes such information, the NCR-MT520A may consider that it is specified (configured) to perform BFD in the RRC inactive state.

[0116] In this embodiment, the second setting information may include information specifying whether or not the NCR-MT520A performs detection processing (BFD) in the RRC inactive state. That is, the gNB200 may set the NCR-MT520A as to whether or not to perform BFD in the RRC inactive state.

[0117] In this embodiment, when the NCR-MT520A is in the RRC inactive state, it may initiate an RRC connection resume to transition to the RRC connected state in response to the detection of a beam failure by the detection process (BFD). That is, when the NCR-MT520A detects a beam failure in the RRC inactive state, it may resume the RRC connection and transition to the RRC connected state. For example, when the NCR-MT520A initiates the RRC connection resume, it selects an available beam before transmitting a random access preamble (Msg1) on the physical random access channel (PRACH) and transmits Msg1 using the PRACH resource associated with that beam (SSB index). The gNB200 identifies the beam (SSB index) selected by the NCR-MT520A from the resources in which Msg1 was received and transmits a random access response (Msg2) using the antenna weight corresponding to that beam. Msg2 includes a UL grant, and NCR-MT520A transmits an RRC Resume Request message (Msg3) to the gNB200. Then, NCR-MT520A receives an RRC Resume message (Msg4) from the gNB200 and transitions to the RRC connected state.

[0118] In this embodiment, the second setting information may include information specifying whether to continue relay operation when the NCR-MT520A detects a beam failure in the RRC inactive state. For example, when the gNB200 detects a beam failure in the RRC inactive state, the gNB200 may set the NCR-MT520A as to whether to turn off the NCR-Fwd510A or to keep it on.

[0119] In this embodiment, when the NCR-MT520A is in the RRC inactive state, it may stop relaying operation in response to the detection of a beam failure by the detection process (BFD) and the failure to identify a candidate beam that satisfies a predetermined quality standard. For example, when the NCR-MT520A detects a beam failure in the RRC inactive state and fails to acquire a new beam that satisfies the quality standard (within a certain time or within a certain number of recovery attempts), it may turn off the NCR-Fwd510A.

[0120] FIG. 15 is a flowchart showing an example of the operation of the NCR device 500A according to the second embodiment.

[0121] In step S21, the NCR-MT520A receives an RRC Reconfiguration message including an NCR configuration from the gNB200. The NCR configuration includes first configuration information related to relay operation. The first configuration information includes configuration information indicating that the NCR-Fwd510A is turned on. The first configuration information may include a periodic beam indication. The NCR configuration may further include second configuration information related to whether the NCR-MT520A performs beam fault detection (BFD) with the gNB200 in the RRC inactive state. Hereinafter, the second configuration information is also referred to as "BFD / BFR configuration for the RRC inactive state."

[0122] In step S22, the NCR-MT 520A in the RRC connected state may perform relay operation using the NCR-Fwd 510A in the ON state, based on the first setting information included in the NCR setting received in step S11.

[0123] In step S23, the NCR-MT 520A in the RRC connected state receives an RRC Release message including a suspend setting from the gNB 200. The NCR-MT 520A transitions to the RRC inactive state in response to the suspend setting. The RRC Release message may include BFD / BFR settings (second setting information) for the RRC inactive state.

[0124] The BFD / BFR configuration for the RRC inactive state includes at least one of the following configuration information a) to c).

[0125] a) Setting whether to perform BFD in RRC inactive state.

[0126] b) Setting of processing when beam failure is detected in RRC inactive state: For example, the setting may include information specifying whether to resume the RRC connection when a beam failure is detected in the RRC inactive state.

[0127] b1) If RRC connection resume is not performed, the configuration may include information specifying whether to turn off NCR-Fwd510A while continuing the RRC inactive state, or to keep NCR-Fwd510A on according to the latest configuration.

[0128] b2) If RRC connection resume is not performed, the configuration may include information specifying whether or not to perform BFR.

[0129] b3) When BFR is performed, the setting may include parameters specifying the conditions for determining a BFR failure. The parameters may include a timer value for the determination and / or an upper limit of the number of attempts for the determination. In this case, the NCR-MT520A in the RRC inactive state may determine that BFR has failed when it is unable to discover (acquire) a candidate beam that satisfies a predetermined quality criterion within the timer value, or when the random access procedure for a candidate beam that satisfies the predetermined quality criterion is unsuccessful. The NCR-MT520A in the RRC inactive state may determine that BFR has failed when the number of times a candidate beam that does not satisfy the predetermined quality criterion has been discovered reaches the upper limit, or when the number of times a random access procedure for a candidate beam that satisfies the predetermined quality criterion has failed reaches the upper limit.

[0130] b4) When BFR is performed, the setting may include information specifying a process to be performed when BFR fails. For example, the information may include information specifying whether the NCR-MT 520A resumes the RRC connection. When RRC resume is not performed (when the RRC inactive state is maintained), the information may include information specifying whether the NCR-Fwd 510A is turned off or maintained on.

[0131] In step S24, the NCR-MT520A that has transitioned to the RRC inactive state performs relay operation using the NCR-Fwd510A in the ON state based on the first setting information included in the NCR setting (latest setting) in the RRC connected state. Also, the NCR-MT520A in the RRC inactive state performs BFD based on the BFD / BFR setting for the RRC inactive state (second setting information).

[0132] In step S25, the NCR-MT520A in the RRC inactive state checks whether or not a beam failure has been detected by BFD. If a beam failure has not been detected, the process returns to step S24.

[0133] If a beam failure is detected (step S25: YES), in step S26, NCR-MT520A in the RRC inactive state performs the operation specified in the BFD / BFR setting (second setting information) for the RRC inactive state (e.g., BFR and / or RRC connection resume) based on the BFD / BFR setting.

[0134] (2.1) Modification of the Second Embodiment In the second embodiment, an example has been described in which the gNB 200 explicitly configures the NCR-MT 520A as to whether or not to perform beam failure detection (BFD) and / or beam failure recovery (BFR). However, this is not limiting. The NCR-MT 520A can determine whether or not to perform beam failure detection and / or beam failure recovery processing in the RRC inactive state based on the operating state of the NCR-Fwd 510A.

[0135] That is, when the NCR-MT520A transitions to the RRC inactive state, if the NCR-Fwd510A is in the on state (for example, performing periodic beamforming operation), the NCR-MT520A performs beam failure detection and / or beam failure recovery processing in the RRC inactive state. Also, if the NCR-Fwd510A is in the off control (not performing relay operation), the NCR-MT520A does not perform beam failure detection and / or beam failure recovery processing in the RRC inactive state. This allows the NCR-MT520A to determine whether or not to perform beam failure detection and / or beam failure recovery processing in the RRC inactive state without explicit configuration from the gNB200.

[0136] (3) Third embodiment Next, a third embodiment will be described, focusing on differences from the above-described embodiments. As shown in Fig. 16, 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."

[0137] 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.

[0138] 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.

[0139] FIG. 17 is a diagram showing an example configuration of a RIS-Fwd (repeater) 510B and a RIS-MT (control terminal) 520B according to the second embodiment. The RIS-MT 520B includes a receiver 521, a transmitter 522, and a controller 523. This configuration is similar to that of the 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.

[0140] (4) Other embodiments In the above-described embodiment, an example has been described in which the relay device that performs relay transmission is the NCR device 500A or the RIS device 500B. However, the relay device that performs relay transmission is not limited to the NCR device 500A or the RIS device 500B, and may be an IAB (Integrated Access and Backhaul) node defined in the 3GPP technical specifications.

[0141] 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.

[0142] In the above embodiment, an example in which the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB). Also, the base station may be a relay node such as an IAB node. The base station may be a DU (Distributed Unit) of the IAB node.

[0143] In the above-described embodiment and example, 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) or a 6G base station. The base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU of the IAB node. The UE 100 may also be an MT (Mobile Termination) of the IAB node.

[0144] That is, the UE 100 may be a terminal function unit (a type of communication module) for a base station to control a repeater that relays signals. Such a terminal function unit is referred to as an MT. Examples of the MT include an NCR (Network Controlled Repeater)-MT and a RIS (Reconfigurable Intelligent Surface)-MT, in addition to the IAB-MT.

[0145] 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.

[0146] A program may be provided that causes a computer to execute each process performed by a communication device according to the above-described embodiment, for example, UE100 (NCR-MT520A, RIS-MT520B) or gNB200. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by UE100 or gNB200 may be integrated, and at least a part of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0147] A program may be provided that causes a computer to execute each process performed by UE100, gNB200, or relay device. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or DVD-ROM. Furthermore, circuits that execute each process performed by UE100, gNB200, or relay device may be integrated, and at least a part of UE100, gNB200, or relay device may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0148] 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 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.

[0149] 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.

[0150] 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.

[0151] This application claims priority to U.S. Provisional Application No. 63 / 501,479 (filed May 11, 2023), the entire contents of which are incorporated herein by reference.

[0152] (5) Appendix A The following additional notes are about the features of the above-described embodiment.

[0153] (Appendix 1) A communication method performed by a relay device having a relay operation for relaying a radio signal transmitted between a network node and a user device, and a control terminal for receiving a control signal used to control the relay from the network node, the method comprising: receiving configuration information related to the relay operation from a first cell; performing the relay operation using the configuration information when the control terminal is in a radio resource control (RRC) inactive state in the first cell; When cell reselection from the first cell to the second cell is performed, stopping the relay operation; When cell reselection to the first cell is performed within a predetermined time after performing cell reselection to the second cell, restarting the relay operation using the configuration information. Communication method.

[0154] (Appendix 2) receiving a timer value from the first cell that defines the predetermined time period; In response to the cell reselection from the first cell to the second cell, starting a timer to which the timer value is set. 1. A communication method as described in Appendix 1.

[0155] (Appendix 3) receiving an RRC release message from the first cell to transition the control terminal from an RRC connected state to the RRC inactive state; The RRC release message includes the timer value. 2. A communication method as described in Appendix 2.

[0156] (Appendix 4) The step of resuming the relay operation includes a step of resuming the relay operation using the configuration information when the cell reselection to the first cell is performed before the timer expires. 4. A communication method according to claim 2 or 3.

[0157] (Appendix 5) the setting information includes a setting of periodic beamforming in the relay operation, The step of resuming the relay operation includes the step of resuming the periodic beamforming using the setting information. 5. A communication method according to any one of claims 1 to 4.

[0158] (Appendix 6) a repeater that performs a relay operation to relay a radio signal transmitted between a network node and a user equipment; a control terminal that receives a control signal used to control the repeater from the network node; The control terminal a receiving unit that receives setting information related to the relay operation from a first cell; a control unit that controls the relay to perform the relay operation using the configuration information when the control terminal is in a radio resource control (RRC) inactive state in the first cell, The control unit When cell reselection from the first cell to the second cell is performed, the relay operation is stopped; When cell reselection to the first cell is performed within a predetermined time after the cell reselection to the second cell is performed, the relay operation using the setting information is resumed. Relay device.

[0159] (Appendix 7) A communication method performed by a relay device having a relay operation for relaying a radio signal transmitted between a network node and a user device, and a control terminal for receiving a control signal used to control the relay from the network node, the method comprising: receiving first configuration information related to the relay operation from the network node; receiving second setting information from the network node regarding whether the control terminal performs a beam failure detection process with the network node in a radio resource control (RRC) inactive state; When the control terminal is in the RRC inactive state, controlling the relay operation based on the first setting information and controlling the detection process based on the second setting information. Communication method.

[0160] (Appendix 8) The second setting information includes information specifying whether or not the control terminal performs the detection process in the RRC inactive state. 7. A communication method as described in Appendix 7.

[0161] (Appendix 9) When the control terminal is in the RRC inactive state, in response to the beam failure being detected by the detection process, the control terminal further includes a step of starting an RRC connection resume for transitioning to an RRC connected state. 9. A communication method according to claim 7 or 8.

[0162] (Appendix 10) The second setting information includes information specifying whether to continue the relay operation when the control terminal detects the beam failure in the RRC inactive state. 10. A communication method according to any one of appendices 7 to 9.

[0163] (Appendix 11) When the control terminal is in the RRC inactive state, the beam failure is detected by the detection process, and in response to failure to identify a candidate beam that satisfies a predetermined quality standard, the method further includes a step of stopping the relay operation. 11. A communication method according to any one of appendices 7 to 10.

[0164] (Appendix 12) a repeater that performs a relay operation to relay a radio signal transmitted between a network node and a user equipment; a control terminal that receives a control signal used to control the repeater from the network node; The control terminal a receiving unit that receives first setting information regarding the relay operation from the network node and receives second setting information regarding whether the control terminal performs a beam failure detection process with the network node in a radio resource control (RRC) inactive state from the network node; a control unit that controls the relay operation based on the first setting information and controls the detection process based on the second setting information when the control terminal is in the RRC inactive state. Relay device.

[0165] (6) Appendix B 1. Introduction RAN#99 approved a three-month extension for the work item on Network Controlled Repeaters (NCRs) to resolve remaining issues for RAN2#119bis-e, RAN2#120, and RAN2#121.

[0166] This appendix discusses the remaining open / potential issues for RAN2 in NCR.

[0167] 2. Discussion 2.1.Wake-up timer As agreed in RAN2, "The network should be able to send the NCR-MT to RRC idle," so the gNB can intentionally put the NCR-MT into idle state due to policies such as NCR power saving or network congestion. However, since RAN paging is not available for idle NCR-MTs, the gNB has no way to transition the NCR-MT to connected, i.e., unreachable. Therefore, it is clear that once the NCR is released into idle state, it is no longer a network-controlled repeater and is considered similar to, for example, a legacy RF repeater.

[0168] Observation 1: Even if the gNB intentionally puts the NCR-MT in an idle state due to policies such as NCR power saving or network congestion, the gNB cannot page the NCR-MT.

[0169] To solve this issue, RAN2#121bis-e discussed whether to rely on OAM implementation or introduce a wake-up timer, but the conclusion was postponed as follows:

[0170] Proposal 1: Rel-18 does not define the "Wake-up Timer" IE in the RRC Release message.

[0171] There is also the idea that "we want to ensure network control in a simple way. The NAS can trigger service requests and registration requests." "Since NCR-WRD is off during RRC idle, the original intent is no longer valid and the only goal is to get back to RRC connected. We believe there are multiple implementation-specific ways to achieve this. There is no time to send an LS to CT1." "The main motivation for opposing timers is the impact on NAS, but that impact appears to be minor. If the impact on NAS is significant, we will agree to an OAM solution." Some believe that the biggest issue is not the impact on NAS, but the motivation for having such a timer. There is also the view that "the timer is handled by the AS, and when the timer expires it notifies the NAS. Since OAM is static and cannot be used in this case, gNB control is preferable." There is also the idea that "in the same case, it may be handled by OAM. RAN3 agrees that OAM is supported." There is also a view that "we need to consider whether interoperability is a key issue within the scope of NCR." Some believe that either solution will work. Further consideration is needed on the above points.

[0172] Therefore, this issue should be discussed thoroughly, a conclusion should be reached, and the Rel-17 NCR WI should be completed.

[0173] 2.1.1. OAM-based solutions In other words, the OAM server generates DL OAM traffic (U-plane data) that triggers the AMF to initiate CN paging to the NCR-MT. However, it is assumed that there is no way for the gNB to send UL OAM traffic (U-plane data, e.g., indicating release to IDLE) when the NCR-MT receives an RRC release after the gNB releases the NCR-MT. Therefore, it is unclear how the OAM server knows that the NCR-MT is idle.

[0174] Observation 2: After the NCR-MT is released by the gNB, there is no way for the NCR-MT to send UL OAM traffic, so OAM does not know whether the NCR-MT is idle or not.

[0175] In addition, it is somewhat unnatural for the gNB to intentionally release the NCR-MT for some purpose while the OAM server is forced to reconnect the NCR-MT. To solve these issues, some coordination between the gNB-OAM and the NCR-OAM must be envisioned. However, this would increase the operator's workload or eliminate multi-vendor interoperability.

[0176] Observation 3: DL OAM traffic could be an option to trigger the AMF to page an idle NCR-MT, but this would require coordination between gNB-OAM and NCR-OAM, leading to inefficient network operations and poor interoperability.

[0177] Another implementation option is to use an OAM client on the NCR-MT. The OAM client can use the NCR-MT's release state as well as failure states (e.g., RLF, RRC resume failure) and initial access states (e.g., power on) to determine the transition of the NCR-MT to the idle state. In the case of failure and initial access, the OAM client may generate UL OAM traffic (i.e., U-plane data) to connect to the OAM server. UL packets trigger the RRC connection establishment procedure, as they do today. That is, for an idle NCR-MT, RRC connection establishment is an automatic process, so the NCR-MT initiates RRC connection establishment immediately after being released from the gNB.

[0178] Observation 4: The use of UL OAM traffic is another option to trigger the NCR-MT to initiate the RRC connection establishment, but it can occur immediately after the gNB releases the NCR-MT to the idle state.

[0179] Given the above observations, OAM-based solutions may introduce other issues, so these implementations will not work correctly on their own.

[0180] On the other hand, the advantages of OAM-based solutions are clearly not impacting the specification.

[0181] Observation 5: The advantage of an OAM-based solution is that it does not impact specifications.

[0182] 2.1.2. Timer-based solutions A wake-up timer was proposed as a trigger for the NCR-MT to return to the RRC connection, and was discussed in RAN2#121 offline and online, and RAN2#121bis-e offline and online. The idea is that the NCR-MT starts a timer (if configured in the RRC release), and when the timer expires, the NCR-MT initiates the RRC connection establishment procedure. This simple solution solves the challenge mentioned in Observation 3 (especially when the OAM server does not implement automatic generation of DL traffic such as keep-alive messages) and allows the gNB to control the idle NCR-MT.

[0183] Keep-alive messages as an OAM-based solution require a large number of unnecessary messages, especially if the gNB rarely puts the NCR-MT in idle state, but this is up to the gNB implementation.

[0184] Observation 6: A wake-up timer can solve the issue identified in Observation 3, especially when the OAM server does not implement so-called keep-alive messages and the RRC connection control is entirely under the control of the gNB.

[0185] With RAN2#121bis-e, some companies were concerned about how much impact it would have on NAS specifications. Generally, the following two approaches are considered:

[0186] AS-based approach When the wake-up timer expires, the AS can behave as if it had received a paging message, i.e., it presents the UE-ID (i.e., UE-Identity) to the NAS. The NAS can also behave as if the access attempt is MT access (i.e., Access Identity 0 and Access Category 0 of "MT_acc"), so the AS can set the establishment cause with MT access according to the NAS access attempt. Since the expiration of the wake-up timer means that the network (i.e., gNB) will call back the NCR-MT connected, this establishment cause (i.e., MT access) is considered to be in line with the current definition. This solution has no (or very little) impact on the NAS specification, but the AS specification needs to be slightly modified to determine the behavior when the timer expires.

[0187] NAS-based approach The AS notifies the NAS when the wake-up timer expires, and the NAS requests the establishment of a signaling connection. This is considered a new definition of an access attempt, and so besides the slight impact on the AS specification of the new behavior on timer expiration, it may require, for example, the addition of procedural descriptions (or annotations) to the NAS specification.

[0188] Another option would be for the AS to forward the wake-up timer value when set in the RRC release. The NAS would then process the timer and request the establishment of a signaling connection upon timer expiry. This solution would require the NAS specification to specify the timer handling in addition to the new definition of the access attempt described above. Therefore, in addition to the new behavior in the AS specification, this option has the most impact on the NAS specification.

[0189] Based on the above analysis, it can be concluded that timers should be handled by the AS to minimize potential NAS impact. Furthermore, an AS-based approach is preferable because it minimizes (or even avoids) impact on other WGs. In this sense, it can be said that there is no longer any major concern about the impact on NAS specifications.

[0190] Observation 7: Wake-up timers have no (or only a very small) impact on the behavior of the NAS as long as the timers are handled by the AS.

[0191] It should be noted that if the OAM-based solution discussed in the previous section is preferred, the gNB will always choose the option of not setting a timer on RRC release, i.e. this option is not harmful and ensures efficient network operation and interoperability.

[0192] Proposal 1: RAN2 should agree to introduce a wake-up timer for gNB to control idle NCR-MT to establish RRC connection.

[0193] Proposal 2: RAN2 should discuss whether the AS should act as if it received a paging message, i.e., whether the AS should indicate its UE-ID to the NAS when the wake-up timer expires.

[0194] If Proposal 1 is acceptable, the timer value needs to be discussed. According to existing mechanisms related to access restriction / prohibition in idle state, 300 seconds (or 5 minutes) is a typical period for a UE to exclude a prohibited cell from cell reselection candidates, and this could be the minimum value for this timer. The discussion in RAN2#121bis-e shows an example in which a gNB may not use NCR during low-traffic periods (e.g., nighttime) and may set NCR to idle. Therefore, a timer upper limit of 12 hours is considered reasonable. If the timer value is 8 bits, the mapping would be, for example, "300 seconds (5 minutes), 10 minutes, 30 minutes, 60 minutes (1 hour), 3 hours, and 12 hours."

[0195] Proposal 3: RAN2 should discuss the range of values ​​for the wake-up timer (e.g., from 300 seconds to 12 hours).

[0196] Proposal 4: RAN2 should discuss how many bits the wake-up timer setting should be (e.g., the baseline is 8 bits).

[0197] Another possibility is an inhibit timer, which causes the NCR-MT to start a timer (if configured in the RRC release) and inhibits the NCR-MT from initiating the RRC connection establishment procedure while the timer is running. This solution solves the problem in observation 3 (especially when the OAM server implements frequent automatic generation of DL traffic such as keep-alive messages) and the challenge in observation 4, and allows the gNB to control even idle NCR-MTs.

[0198] Observation 8: The prohibition timer, like observation 4, can solve the problem identified in observation 3 (especially when keep-alive messages occur frequently), and the RRC connection control of the NCR-MT is entirely under the control of the gNB.

[0199] In other words, an idle NCR-MT can also be network controlled, which is considered more efficient as it does not require two separate timers for the wake-up timer and the inhibit timer.

[0200] Observation 9: The wake-up timer and inhibit timer combined into one timer is efficient and feasible.

[0201] Proposal 5: If Proposal 1 is acceptable, RAN2 should further discuss whether to prohibit the NCR-MT from initiating RRC connection establishment while the wake-up timer is running, i.e., whether the wake-up timer also functions as a prohibition timer (one timer).

[0202] While it is clear that RRC connection establishment via UL traffic (e.g., UL OAM client packets) would be prohibited if proposal 5 is accepted, it is worth considering whether the same is really true for DL ​​traffic (e.g., DL OAM server packets). If RRC connection establishment via DL traffic is prohibited, the NCR will be unreachable from the network / OAM client while the timer is running. Therefore, the prohibition timer should only apply to RRC connection establishment via UL traffic. For example, this could be the case if the gNB wants to prevent the NCR-MT from returning to connected via DL traffic (e.g., by OAM server keep-alive messages). Therefore, whether this restriction should be configurable by the gNB is a separate issue.

[0203] Proposal 6: If proposal 5 can be agreed upon, RAN2 should further discuss whether the prohibition timer can be applied only to UL traffic (e.g., OAM client), i.e., whether RRC connection establishment is allowed for DL ​​traffic (e.g., OAM server, paging reception) when the timer is running.

[0204] Proposal 7: If Proposal 6 can be agreed upon, RAN2 should further discuss whether the limit can be set by the gNB, i.e., whether the prohibition timer applies only to UL traffic or to both DL and UL traffic.

[0205] 2.2. Beam Monitoring Inactivity in RRC As background, RAN2#120 agreed to the on or off operation of NCR-Fwd when NCR-MT is connected and inactive.

[0206] NCR-FW on / off When NCR-MT is in RRC connected mode, NCR-Fwd can be turned on or off according to the side control information received from the gNB. After NCR-MT enters RRC inactive mode, NCR-Fwd can be turned on or off according to the last configuration received from the gNB. Further consideration is needed regarding the release to RRC idols.

[0207] Finally, RAN2#121bis-e agreed to use the idle NCR-MT.

[0208] When NCR-MT is in RRC idle state, NCR-Fwd is off.

[0209] According to the above agreement, the basic principles of NCR are considered to be as follows: When NCR-MT is connected or inactive, NCR-Fwd is under the control of gNB. NCR-Fwd is considered out of control by the gNB when NCR-MT is idle.

[0210] Finding 10: NCR-Fwd is under the control of gNB when NCR-MT is inactive.

[0211] Another background is that in RAN2#121, it is agreed that the NCR-MT will resume the RRC connection immediately after cell reselection to a different cell and provide a new side control configuration.

[0212] · If an NCR-MT in RRC inactive state reselects a cell different from the last serving cell for which it received side control configuration, NCR-FWD is turned off. After cell reselection, the NCR-MT resumes receiving side control configuration from the new gNB (possible via network configuration using existing specifications). Further study is needed on the cases where the NCR-MT moves to an acceptable cell and returns, and where no cell is found.

[0213] Observation 11: If the NCR-MT reselects a different cell, NCR-Fwd is already turned off and the NCR-MT must restart the RRC connection to the new cell to provide side control configuration.

[0214] In addition to these, RAN2#121bis-e is discussing whether beam monitoring of backhaul links is required when NCR-MT is inactive.

[0215] Proposal 4: If necessary, the implementation can perform beam monitoring of the backhaul link when the NCR-MT is in the RRC inactive state.

[0216] Some people say, "I'm not opposed, but I have doubts about what 'implementation' means." One question is, "What happens if NCR-FWD selects a new beam during RRC inactivity?" There is also the idea that "it is up to the network whether to send the UE to RRC inactive, and the network needs to be aware of the situation (e.g. whether the beam can be changed) and in that case can keep the UE RRC connected." Some people are saying, "Can we agree that NCR-FWD is off in this case?" There is also an opinion that "in the inactive state, we want to prevent the beam from being changed without the network noticing." The above may be further discussed.

[0217] An important point in the above discussion was what happens when a beam failure is detected by an inactive NCR-MT. According to the previous discussion, the possible actions are as follows:

[0218] ·Alt.1: Turn off NCR-Fwd if beam obstruction is detected or beam obstruction recovery fails. ·Alt.2: If a beam failure is detected, the NCR-MT restarts the RRC connection.

[0219] Considering the principle of Observation 10, Alt.1 is unacceptable because it means that NCR-Fwd can be automatically turned off even if NCR-MT is still camped on the cell that provided the last side control setting. Alternatively, Alt.1 could mean that NCR itself can control whether NCR-Fwd is on or off even if NCR-MT is connected, which is not only inappropriate but also violates the RAN2 agreement mentioned above.

[0220] On the other hand, Alt.2 can be considered a variant of NCR behavior during cell reselection in Finding 11. That is, Alt.2 requires the NCR-MT to acquire a new side control configuration upon beam failure. Therefore, Alt.2 is considered a viable solution, although there may be cases where NCR-Fwd needs to be turned off upon beam failure detection, as in Alt.1. On the other hand, offline discussions point out that the gNB monitors the end-to-end radio link with the UE, and therefore, depending on the implementation, it can detect such failures. This is rather consistent with the principle identified in Finding 10, namely, that NCR is under the control of the gNB when the NCR-MT is inactive.

[0221] In summary, Alt.2 is a visible solution, but at the same time it is not a necessary one: considering the time remaining to solve other necessary issues, beam monitoring in inactive mode does not need to be supported, at least not in Rel-18.

[0222] Proposal 8: RAN2 should agree that inactive beam monitoring will not be supported in this release.

[0223] 2.3. Frequency Prioritization in Cell Reselection By way of background, RAN2#120 agreed to the following statement: NCR-MT supports cell reselection and RRM measurements in RRC idle and RRC inactive.

[0224] In Rel-18, NCR-MT does not support handover and RRM measurements in RRC Connected.

[0225] A problem in cell reselection is the priority handling of specific cells. In the case of legacy RF repeaters, their placement is determined by network planning and / or field RF measurements. Therefore, it is assumed that desired cell(s) are planned for each NCR. That is, network planning determines the relationship between the serving cell and the NCR. Such desired cells may be configured into NCRs by OAM.

[0226] Observation 12: The NCR can configure a desired cell, for example, by OAM, where the desired cell means the cell that the NCR-MT intends to camp on and / or connect to.

[0227] In fact, RAN3 supports the BL CR of the Stage-2 specification, and the allowed cell list and forbidden cell list can be set by the OAM server to the NCR (i.e., the OAM client).

[0228] XY OAM aspects The transport connection between the NCR node and its OAM is provided by the NCR-MT PDU session. The NCR may be configured with a list of gNB cells to which the NCR-MT is allowed to connect and / or a list of gNB cells to which the NCR-MT is prohibited from connecting.

[0229] Since NCR-MT is a type of UE, it is obvious that NCR-MT must follow the idle / inactive mode behavior specified in TS38.304. In the email discussion of RAN2#121bis-e, some companies thought that the Stage-2 specification above allows NCR implementations to override the behavior specific to TS38.304. However, this is not consistent with the 3GPP specification suite and common sense in its implementation. Therefore, standard support is necessary to ensure network planning for NCR.

[0230] Furthermore, RAN3 states that NCRs are allowed to connect to allowed cells, i.e., it makes no guarantees about camping on allowed cells. Similarly, the Stage-2 specification states that NCRs are not allowed to connect to forbidden cells, i.e., it makes no assumptions about avoiding camping on forbidden cells. In such cases, we need to consider what happens if the UE cannot camp on an allowed cell (due to frequency priority and / or radio conditions) even if the allowed cell meets the S criteria, and what happens if the UE camps on a forbidden cell (because the RAN3 specification does not mention camping, it simply mentions not connecting to a cell).

[0231] Observation 13: The specification of allowed cell lists and forbidden cell lists in Stage-2 of RAN3 does not mean that the implementation of NCR-MT is allowed to override the cell reselection procedure strictly specified in TS38.304.

[0232] The simplest approach is to enhance the cell reselection prioritization process. Similar to MBS and sidelink frequencies (which are prioritized according to UE preferences), exceptions to the NCR-MT prioritization process can be defined, allowing allowed cells to be considered the highest priority and barred cells the lowest priority. This enhancement allows the NCR-MT to always measure and attempt to reselect allowed cells and to avoid reselecting barred cells. Therefore, it is necessary to define these exceptions at least at the frequency level when the NCR-MT requires such prioritization, i.e., when the cell list is configured by OAM.

[0233] The simplest approach is to enhance the cell reselection prioritization process. Similar to MBS and sidelink frequencies (which are prioritized according to UE preferences), exceptions to the NCR-MT prioritization process can be defined, allowing allowed cells to be considered the highest priority and barred cells the lowest priority. This enhancement allows the NCR-MT to always measure and attempt to reselect allowed cells and to avoid reselecting barred cells. Therefore, it is necessary to define these exceptions at least at the frequency level when the NCR-MT requires such prioritization, i.e., when the cell list is configured by OAM.

[0234] Proposal 9: RAN2 should agree that the NCR-MT will consider certain frequencies as highest or lowest priority based on the expected functionality of the NCR-MT (e.g., when allowed cell lists and / or forbidden cell lists are configured by OAM).

[0235] Considering that NCR-MTs are deployed at the cell edge (i.e., extending the coverage of the macro cell), ranking may cause the NCR-MT to reselect an undesirable cell on the same frequency.

[0236] Proposal 10: RAN2 should discuss whether NCR-MT is allowed to prioritize specific cells (cells of interest) in the intra-frequency cell reselection procedure.

[0237] 2.4. RRC Release with Redirection RAN2#121bis-e agreed to continue supporting redirection for UE as it is now. RAN2 checks that RRC release with redirection is applicable to NCR-MT and that NCR-Fwd is off if NCR-MT selects a new cell by redirection (no impact on specification).

[0238] As specified in RAN3, the NCR is configured with an allowed cell list and / or a forbidden cell list, so the NCR-MT can identify the frequencies of the allowed / forbidden cells using, for example, inter-frequency cell reselection information provided by SIB4. Since cell selection is performed at the time of redirection configuration, it is up to the NCR-MT implementation to select which cell on the identified frequency.

[0239] On the other hand, since the gNB may not know the frequencies of interest of the NCR-MT or the allowed / forbidden cell list set in the NCR by the NCR's OAM, the challenge remains as to how the gNB can identify a specific frequency for redirection, i.e., how to set the redirectedCarrierInfo IE.

[0240] Observation 14: It is not clear how the gNB sets redirectedCarrierInfo in RRC release, since the gNB may not know the allowed / forbidden cell lists configured in the NCR by OAM and the corresponding frequencies on which these cells operate.

[0241] That is, the operator enters all allow / prohibit lists set by the NCR OAM into each NCR within the gNB's coverage area. This solution does not affect the specifications, but it places a heavy burden on the operator every time an NCR is deployed in the network.

[0242] Another solution is to enable the NCR-MT to notify the gNB of the allowed / forbidden cell list through UE Assistance Information, UE Capability, etc. This automatic configuration reduces the operator's workload regarding this configuration, and was approved by the RAN plenary.

[0243] Therefore, RAN2 should at least discuss how to address this issue in the Rel-18 NCR.

[0244] Proposal 11: RAN2 should discuss whether the gNB should identify the specific frequency to be set in the redirectedCarrierInfo IE within the RRC release based on the OAM implementation or a new UE report. [Explanation of symbols]

[0245] 1: Mobile communication system 100:UE 200 :gNB 210: Transmission unit 220: Receiving unit 230: Control unit 240: Backhaul communication unit 300A:AMF 400: OAM Server 500A:NCR device 510A: NCR-Fwd 520A: NCR-MT 500B :RIS device 510B:RIS-Fwd 520B: RIS-MT 511A: Wireless unit 511a: Antenna part 511b :RF circuit 511c: Directivity control unit 512A: NCR control unit 512B: RIS control unit 521: Receiving unit 522: Transmission unit 523: Control unit 530: Interface

Claims

1. A communication method performed by a relay device having a relay operation for relaying a radio signal transmitted between a network node and a user device, and a control terminal for receiving a control signal used to control the relay from the network node, the method comprising: receiving configuration information relating to the relay operation from the network node; and when the control terminal is in a radio resource control (RRC) inactive state, controlling the relay operation based on the configuration information and determining beam degradation between the network node and the relay. Communication method.

2. When the control terminal is in the RRC inactive state, in response to determining the beam deterioration, the control terminal starts an RRC connection resume for transitioning to an RRC connected state. The communication method according to claim 1 .

3. When the control terminal is in the RRC inactive state, the control terminal stops the relay operation in response to determining that the beam has deteriorated. The communication method according to claim 1 .

4. a repeater that performs a relay operation to relay a radio signal transmitted between a network node and a user equipment; a control terminal that receives a control signal used to control the repeater from the network node; The control terminal a receiving unit that receives setting information related to the relay operation from the network node; a control unit that controls the relay operation based on the configuration information when the control terminal is in a radio resource control (RRC) inactive state, and determines beam degradation between the network node and the relay. Relay device.

5. A mobile communication system comprising a network node, a user equipment, and a relay device, The relay device a repeater that performs a relay operation to relay a radio signal transmitted between the network node and the user equipment; a control terminal that receives a control signal used to control the repeater from the network node; The control terminal a control unit that receives configuration information related to the relay operation from the network node, and when the control terminal is in a radio resource control (RRC) inactive state, controls the relay operation based on the configuration information, and determines beam degradation between the network node and the relay. Mobile communication system.

6. A relay device having a repeater that performs a relay operation to relay a radio signal transmitted between a network node and a user device, and a control terminal that receives a control signal used to control the repeater from the network node, receiving configuration information relating to the relay operation from the network node; and when the control terminal is in a radio resource control (RRC) inactive state, controlling the relay operation based on the configuration information and determining beam degradation between the network node and the relay. program.

7. A chipset for a relay device having a relay device that performs a relay operation to relay a radio signal transmitted between a network node and a user device, and a control terminal that receives a control signal used to control the relay device from the network node, receiving configuration information relating to the relay operation from the network node; and when the control terminal is in a radio resource control (RRC) inactive state, controlling the relay operation based on the configuration information and determining beam degradation between the network node and the relay. Chipset.

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