WO2024171983A1 - Communication method and relay device - Google Patents

Abstract

This communication method is to be used by a relay device, which includes a plurality of repeaters that each perform a relay operation for relaying a wireless signal transmitted between a network and a user device, and a control terminal that receives from the network a control signal used to control the plurality of repeaters, the method including: a step for identifying a total transmission power for the plurality of repeaters; and a step for configuring and/or controlling the plurality of repeaters so that the total transmission power does not exceed a maximum transmission power that has been specified for the relay device.

Description

Communication method and relay device

This disclosure relates to a communication method and relay device used in a mobile communication system.

In recent years, fifth-generation (5G) mobile communication systems have been attracting attention. NR (New Radio), the wireless access technology of the 5G system, is capable of broadband transmission using higher frequencies than LTE (Long Term Evolution), the fourth-generation wireless access technology.

High-frequency radio signals (radio waves) in the millimeter wave or terahertz wave bands have a high degree of directionality, which makes the reduction of base station coverage an issue. To solve this issue, attention has been focused on repeater devices, which are a type of relay device that relays radio signals between a network and user devices and can be controlled from the network (see, for example, Non-Patent Document 1). Such repeater devices can expand the coverage of base stations while suppressing interference, for example by amplifying radio signals received from base stations and transmitting them directional. Note that such repeater devices are also called NCRs (Network-Controlled Repeaters).

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

The communication method according to the first aspect is a communication method used in a relay device having a plurality of repeaters each performing a relay operation to relay a radio signal transmitted between a network and a user device, and a control terminal receiving a control signal from the network for use in controlling the plurality of repeaters, and includes the steps of: determining a total transmission power for the plurality of repeaters; and configuring and/or controlling the plurality of repeaters so that the total transmission power does not exceed a maximum transmission power determined for the relay device.

The relay device according to the second aspect includes a plurality of repeaters each performing a relay operation to relay a radio signal transmitted between a network and a user device, a control terminal receiving a control signal from the network for use in controlling the plurality of repeaters, and a control unit that determines the total transmission power of the plurality of repeaters, and the control unit sets and/or controls the plurality of repeaters so that the total transmission power does not exceed a maximum transmission power determined for the relay device.

1 is a diagram showing a configuration of a mobile communication system according to an embodiment. A diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data. A diagram showing the configuration of a protocol stack of the wireless interface of the control plane that handles signaling (control signals). FIG. 1 is a diagram illustrating an example of an application scenario of an NCR device (relay device) according to the first embodiment. FIG. 2 is a diagram illustrating an example of an application scenario of the NCR device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a control method for an NCR device according to the first embodiment. FIG. 2 is a diagram showing an example of the configuration of a protocol stack in a mobile communication system having an NCR device according to the first embodiment. 1 is a diagram showing a specific example of the configuration of a mobile communication system having an NCR device according to a first embodiment; 1 is a diagram illustrating an example of the configuration of an NCR device according to a first embodiment. FIG. 2 is a diagram showing a configuration of a UE (user equipment) according to an embodiment. A diagram showing an example configuration of a gNB (base station) according to an embodiment. FIG. 2 is a diagram for explaining the multi-beam operation of the NCR device. FIG. 13 is a diagram for explaining a comparative example. A diagram to explain options for supporting multi-beam/sub-band operation. 11 is a diagram for explaining NCR setting information having a "ToAddModList" structure according to the first embodiment. FIG. A diagram for explaining a CA/DC scenario. A diagram for explaining a CA/DC scenario. 11 is a diagram showing NCR setting information in a ToAddMod list format according to the first embodiment. FIG. FIG. 11 is a diagram illustrating an operation example according to the first embodiment. FIG. 11 is a diagram illustrating an operation example according to the second embodiment. FIG. 13 is a diagram illustrating an example of operation according to a first modification of the second embodiment. 13A to 13C are diagrams for explaining the operation according to the second modification of the second embodiment. FIG. 13 is a diagram illustrating an example of operation according to a second modification of the second embodiment. FIG. 13 is a diagram for explaining DC. 13A to 13C are diagrams for explaining the operation according to the third modification of the second embodiment. FIG. 13 is a diagram illustrating an example of operation according to a third modification of the second embodiment. FIG. 13 is a diagram for explaining an operation example according to the third embodiment. FIG. 13 is a diagram for explaining a RIS device (relay device) according to a fourth embodiment. FIG. 13 is a diagram for explaining a RIS device (relay device) according to a fourth embodiment. FIG. 13 is a diagram for explaining a modification of the fourth embodiment. FIG. 13 is a diagram illustrating an example of operation according to a modification of the fourth embodiment.

The mobile communication system according to the embodiment will be described with reference to the drawings. In the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(1) First Embodiment A description will be given of the 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.

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

The mobile communication system 1 complies with the 5th Generation System (5GS) standard of the 3rd Generation Partnership Project (3GPP) (registered trademark; the same applies below). In the following description, 5GS is used as an example, but the mobile communication system may also be at least partially applied to an LTE (Long Term Evolution) system. The mobile communication system may also be at least partially applied to a sixth generation (6G) system.

The mobile communication system 1 has 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. In the following, the NG-RAN 10 may be simply referred to as the RAN 10. Also, the 5GC 20 may be simply referred to as the core network (CN) 20. The RAN 10 and the CN 20 constitute the network 5 of the mobile communication system 1.

UE100 is a mobile wireless communication device. UE100 may be any device that is used by a user. For example, UE100 is a mobile phone terminal (including a smartphone) and/or a tablet terminal, a notebook PC, a communication module (including a communication card or 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).

NG-RAN10 includes base station (referred to as "gNB" in the 5G system) 200. gNB200 are connected to each other via an Xn interface, which is an interface between base stations. gNB200 manages one or more cells. gNB200 performs wireless communication with UE100 that has established a connection with its own cell. gNB200 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. "Cell" is used as a term indicating the smallest unit of a wireless communication area. "Cell" is also used as a term indicating a function or resource for performing wireless communication with UE100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

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

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

5GC20 includes AMF (Access and Mobility Management Function) and UPF (User Plane Function) 300. AMF performs various mobility controls for UE100. AMF manages the mobility of UE100 by communicating with UE100 using NAS (Non-Access Stratum) signaling. UPF controls data forwarding. AMF and UPF are connected to gNB200 via the NG interface, which is an interface between a base station and a core network.

Figure 2 shows the protocol stack configuration of the wireless interface of the user plane that handles data.

The user plane radio interface protocol has 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.

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 PDCCH using a radio network temporary identifier (RNTI) and obtains 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.

The gNB 200 also transmits a synchronization signal block (SSB: Synchronization Signal/PBCH block). For example, the SSB is composed of four consecutive OFDM (Orthogonal Frequency Division Multiplex) symbols, and includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH)/master information block (MIB), and a 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.

The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of gNB200 via a transport channel. The MAC layer of gNB200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be assigned to UE100.

The RLC layer uses the functions of the MAC layer and PHY layer to transmit data to the RLC layer on the receiving side. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of gNB200 via logical channels.

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

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

Figure 3 shows the configuration of the protocol stack for the wireless interface of the control plane that handles signaling (control signals).

The protocol stack of the radio interface of the control plane has an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer instead of the SDAP layer shown in Figure 2.

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 in response 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.

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 UE100 and the NAS layer of AMF300A. In addition to the radio interface protocol, UE100 also has an application layer, etc. Also, the layer below the NAS layer is called the AS layer.

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

Compared to 4G/LTE, 5G/NR is capable of wideband transmission using higher frequency bands. Radio signals in high frequency bands such as the millimeter wave band or terahertz wave band have high line-of-sight properties, so reducing the coverage of gNB200 becomes an issue. In FIG. 4, UE100 may be located outside the coverage area of gNB200, for example, outside the area where radio signals can be received directly from gNB200. There may be an obstruction between gNB200 and UE100, and UE100 may not be able to communicate with gNB200 within line-of-sight.

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

For example, the NCR device 500A amplifies the radio signal (radio wave) received from the gNB 200 and transmits it by directional transmission. Specifically, the NCR device 500A receives the 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 transmit the radio signal with a variable (adaptive) directional beam. This allows the coverage of the gNB 200 to be efficiently expanded.

Also, as shown in FIG. 5, a new UE (hereinafter referred to as "NCR-MT (Mobile termination)") 100B, which is a type of control terminal for controlling the NCR device 500A, is introduced. That is, the NCR device 500A has 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, changes the propagation state of the radio signal without demodulating or modulating the radio signal, and an NCR-MT 520A that performs wireless communication with the gNB 200 and controls the NCR-Fwd 510A. In this way, the NCR-MT 520A controls the NCR device 500A in cooperation with the gNB 200 by establishing a wireless connection with the gNB 200 and performing wireless communication with the gNB 200. This makes it possible to realize efficient coverage expansion using the NCR device 500A. NCR-MT520A controls NCR device 500A according to control from gNB200. NCR-MT520A also has functions similar to those of UE100.

NCR-MT520A may be configured separately from NCR-Fwd510A. For example, NCR-MT520A may be located near NCR-Fwd510A and electrically connected to NCR-Fwd510A. NCR-MT520A may be connected to NCR-Fwd510A by wire or wirelessly. Alternatively, NCR-MT520A may be configured integrally with NCR-Fwd510A. NCR-MT520A and NCR-Fwd510A may be fixedly installed, for example, at the coverage edge (cell edge) of gNB200 or on a wall or window of a building. NCR-MT520A and NCR-Fwd510A may be installed, for example, in a vehicle or the like, and may be mobile. Additionally, one NCR-MT520A may control multiple NCR-Fwd510A.

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

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

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

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

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

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

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

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

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

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

The gNB 200 (transmitter 210) transmits an NCR control signal to the NCR-MT 520A. The NCR control signal may be an RRC message, which is a control signal of the RRC layer (i.e., layer 3). The NCR control signal may be a MAC 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-specific signaling. The NCR control signal may be broadcast signaling. The NCR control signal may be a fronthaul message (e.g., an F1-AP message). If the NCR-MT 520A is a type or part of a base station, the NCR-MT 520A may communicate with the gNB 200 via an Xn AP (Xn-AP), which is an interface between base stations.

Hereinafter, the NCR control signal transmitted in the RRC message (and/or MAC CE) and used for static or quasi-static control of the NCR-Fwd 510A is also referred to as "NCR setting information" or simply "setting information." Here, the RRC message may be an RRC Reconfiguration message. The NCR setting information includes, for example, information for setting the on/off state of the NCR-Fwd 510A. The NCR setting information may include, for example, information for quasi-static beam setting of the NCR-Fwd 510A.

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

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

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

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

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

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

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

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

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

When one NCR-MT 520A controls multiple NCR-Fwds 510A, the gNB 200 (transmitter 210) may transmit an NCR control signal to the NCR-MT 520A for each NCR-Fwd 510A. In this case, the NCR control signal may include an identifier (NCR identifier) of the corresponding NCR-Fwd 510A. The NCR-MT 520A (controller 523) that controls multiple NCR-Fwds 510A determines the NCR-Fwd 510A to which the NCR control signal is to 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 together with the NCR control signal, even when the NCR-MT 520A controls only one NCR-Fwd 510A.

In this way, NCR-MT520A (control unit 523) controls NCR-Fwd510A based on an NCR control signal from gNB200. This enables gNB200 to control NCR-Fwd510A via NCR-MT520A.

(1.3) Example of Configuration of Each Device An example of the configuration of each device in the mobile communication system 1 according to the embodiment will be described.

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

The NCR-Fwd 510A has a radio unit 511A and an NCR control unit 512A. The radio unit 511A has 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 an analog radio signal into a digital signal and reconvert it into an analog signal after digital signal processing. The directivity control unit 511c may perform analog beamforming by analog signal processing. The directivity control unit 511c may perform digital beamforming by 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.

The NCR-MT 520A has a receiving unit 521, a transmitting unit 522, and a control unit 523. The receiving unit 521 performs various receptions under the control of the control unit 523. The receiving unit 521 includes an antenna and a receiver. The receiver converts a radio signal (wireless signal) received by the antenna into a baseband signal (received signal) and outputs it to the control unit 523. The transmitting unit 522 performs various transmissions under the control of the control unit 523. The transmitting unit 522 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmitted signal) output by the control unit 523 into a radio signal and transmits it from the antenna. The control unit 523 performs various controls in the NCR-MT 520A. The operations of the NCR-MT 520A (and the NCR device 500A) described above and below may be operations under the control of the control unit 523. The control unit 523 includes at least one processor and at least one memory. The memory stores the 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 the programs stored in the memory to perform various processes. The control unit 523 also executes the functions of at least one of the layers of PHY, MAC, RRC, and F1-AP.

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).

In this 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.

(1.3.2) Example of the configuration of a user device FIG. 10 is a diagram showing the configuration of a UE 100 (user device) according to an 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 configure a wireless communication unit that performs wireless communication with the gNB 200.

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 the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130.

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 the baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

The control unit 130 performs various controls and processes in the UE 100. Such processes include processes for 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. The CPU executes programs stored in the memory to perform various processes.

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

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.

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.

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

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

(1.4) Operation According to the First Embodiment The operation according to the first embodiment will be described.

(1.4.1) Overview of Operation According to First Embodiment FIG. 12 is a diagram for explaining the multi-beam operation of the NCR device 500A.

The NCR device 500A processes multiple beams formed for each UE 100. Each beam can carry a different PDSCH and/or PDCCH for a different UE 100. An NCR device 500A performing such multi-beam operation is expected to improve spectral efficiency, coverage, and scheduling flexibility for multiple UEs 100 compared to a simple NCR device 500A that can only process one beam (i.e., one beam information).

In the illustrated example, gNB200 forms beams toward NCR device 500A in two frequency subbands (also referred to as "subbands" or simply "bands" or "frequencies"). One band #1 transmits PDSCH and/or PDCCH for UE #1, and the other band #2 transmits PDSCH and/or PDCCH for UE #2. NCR device 500A transmits PDSCH and/or PDCCH of band #1 by a beam toward UE 100 #1. NCR device 500A also transmits PDSCH and/or PDCCH of band #2 by a beam toward UE 100 #2.

Such multi-beam and/or sub-band operation is expected to improve system capacity. Sub-band operation is achieved by using multiple NCR-Fwd510A. Currently, there is no discussion in 3GPP about supporting multiple NCR-Fwd510A.

Currently, 3GPP has agreed that the gNB cell to which NCR-Fwd 510A is forwarding is the same as the cell to which NCR-MT 520A is connected, and whether NCR-Fwd 510A can forward other cells is up to the implementation. In other words, 3GPP has agreed that NCR-Fwd 510A can forward (relay) signals between multiple cells. Therefore, it is reasonable to interpret that multiple NCR-Fwd 510A can forward signals in multiple subbands within a cell.

On the other hand, as shown in the comparative example of FIG. 13, an implementation can be considered in which multiple NCR devices 500A are used to process multiple signals for each subband and/or each UE 100 separately. Different NCR devices 500A can have different band pass filters (BPFs), and each NCR device 500A can be configured with different beamforming vectors for different UEs 100. In practice, multiple NCR devices 500A can be placed in one chassis to save physical space for installation. However, such an implementation is obviously inefficient. Each NCR device 500A needs to have a separate NCR-MT 520A, and each NCR-MT 520A needs to establish a different RRC connection to the same gNB 200. Therefore, the number of beams/subbands must be equal to the number of RRC connections. This leads to a large signaling overhead for controlling the NCR device 500A.

Thus, multi-beam/sub-band operation is feasible when multiple NCR devices 500A are installed (e.g., co-located). However, it is not efficient in terms of signaling overhead, i.e., the number of RRC connections would be increased to support multiple NCR devices 500A.

Supporting multi-beam/subband operation leads to the discussion of whether one NCR device 500A (or one NCR-MT 520A) can support multiple NCR-Fwds 510A. Similarly, one can further consider whether one NCR-Fwd 510A can support control of multiple "antenna array subgroups". These options are shown in Figure 14. In the illustrated example, option (a) has one NCR-MT 520A handling three NCR-Fwds 510A, while option (b) has one NCR-Fwd 510A with two antenna array subgroups. Either multiple NCR-Fwds 510A or multiple antenna array subgroups can handle different beams to different UEs 100 assigned different resource blocks in the same slot. In the case of multiple NCR-Fwds 510A, the NCR device 500A needs to simultaneously process different beamforming vectors for each NCR-Fwd 510A indicated by the gNB 200.

As for the two options in Figure 14, both option (a) and option (b) serve the same purpose. Currently, only three logical functions, namely "NCR device 500A", "NCR-MT 520A" and "NCR-Fwd 510A", are discussed in 3GPP. To avoid potential confusion and complexity in standardization, option (a) is suitable for modeling an NCR device 500A that supports multi-beam/sub-band operation. Therefore, it is desirable to be able to associate one NCR-MT 520A with multiple NCR-Fwd 510A (i.e., option (a) in Figure 14).

For signaling support of multiple NCR-Fwds 510A via a single NCR-MT 520A, NCR configuration information via RRC needs to be provided to each NCR-Fwd 510A. Similar to the carrier aggregation (CA) configuration, the "ToAddModList" structure can be reused in the signaling structure. Figure 15 is a diagram for explaining NCR configuration information having a "ToAddModList" structure. Similar to each secondary cell (SCell) configuration of CA, each entry in the list defines a set of NCR configuration information for the NCR-Fwd 510A. Since a basic NCR device 500A has one NCR-MT 520A and one NCR-Fwd 510A, the gNB 200 can configure the list with only one entry. Therefore, when such basic NCR devices 500A and advanced NCR devices 500A are deployed together, signaling overhead is minimized. Therefore, it is preferable to define the "ToAddModList" of the NCR-Fwd 510A settings to handle different settings of each NCR-Fwd 510A belonging to the NCR-MT 520A.

As for the details of the contents of each entry, similar to the conventional ToAddModList structure, the ID (also called the "setting ID" or "entry ID") is used to change or delete at least the settings of the NCR-Fwd 510A.

It has been agreed that in order to identify side control information (SCI), the CRC bits of the PDCCH carrying the side control information are scrambled by a new dedicated RNTI. The new dedicated RNTI (also referred to as "NCR-RNTI") is an additional RNTI for NCR-MT 520A to identify the PDCCH carrying SCI, and the C-RNTI is also set in NCR device 500A. Also, since it is assumed that the NCR-RNTI is associated with NCR-Fwd 510A, different NCR-RNTIs can identify different NCR-Fwds 510A. Therefore, a new dedicated RNTI ("NCR-RNTI") is assumed to be available for SCIs addressed to NCR-Fwd 510A, so that different RNTIs can be mapped to different NCR-Fwds 510A.

For the NCR-MT 520A to receive different SCIs for different NCR-Fwds 510A, it is necessary to set an NCR-RNTI value in each entry of the list and associate the NCR-Fwd 510A with the NCR-RNTI. In this configuration, the SCI design of the basic NCR device 500A (i.e., with a single NCR-Fwd 510A) can be reused as is. When the NCR-MT 520A receives the SCI carried by the PDCCH, it can identify which NCR-Fwd 510A should be controlled by the received SCI from the NCR-RNTI that scrambles the PDCCH. Therefore, each entry in "ToAddModList" sets the ID (index of NCR-Fwd510A), the new dedicated RNTI (NCR-RNTI), and various settings of NCR-Fwd510A to NCR-MT520A.

Note that at least one of the carriers of the NCR-MT520A must operate in the frequency band forwarded (relayed) by the NCR-Fwd510A. In addition, the NCR-MT520A and NCR-Fwd510A operating in the same frequency band are being considered as a priority. The intention is to simplify the control link procedure by utilizing the same channel conditions as the backhaul link. In other words, the control link and backhaul link operating in the same frequency have the same radio channel conditions.

In carrier aggregation (CA) and dual connectivity (DC), the primary/secondary cell (PSCell) and secondary cell (SCell) do not have an RRC connection to the NCR-MT 520A. Therefore, the NCR device 500A can only transfer signals to and from the primary cell (PCell). Based on the implementation, the wideband NCR-Fwd 510A (e.g., the supported bandwidth of the NCR-Fwd 510A is equal to the operating band) can transfer signals to and from other cells (e.g., SCell) in the same band as the PCell. Such an implementation is particularly useful for intraband carrier aggregation (CA)/dual connectivity (DC).

However, such artificial limitations are too restrictive in practice, especially in the case of DC. Since the secondary cell group (SCG) has an independent scheduler and independent resource allocation for the UEs 100 it serves, it is effective for the SCG to control the NCR device 500A separately from the master cell group (MCG). Furthermore, in the case of inter-band CA/DC, it is necessary to install another NCR device 500A for another band in order to set up CA/DC with the UEs 100 in the coverage extended by the NCR device 500A.

When considering support for CA/DC setup for the NCR device 500A, the following two scenarios are envisaged. For robust control plane connectivity, the NCR-MT 520A can be configured with a PCell (for RRC connection) in FR (Frequency Range) 1 and an SCell (for side control information, therefore at the same frequency as the NCR-Fwd 510A) in FR2, as shown in FIG. 16. Considering that the NCR device 500A is a network node, a robust RRC connection in FR1/PCell has various advantages.

Another scenario is user plane improvement using CA/DC. To achieve higher data rates, the gNB 200 configures the UE 100 using CA or DC, as shown in FIG. 17, to achieve higher bandwidth and connectivity in heterogeneous environments, respectively. In the case of CA, the NCR-Fwd 510A transfers the aggregated carriers from the backhaul link to the access link. This applies to intraband CA.

In the case of interband CA, the control link must also be CA. The SCI of different cells is identified by the cell ID of the source of the SCI and, if necessary, by the NCR-RNTI. If the configuration of multiple NCR-Fwds 510A is supported, a serving cell ID is added to each entry in the list of NCR-Fwd 510A configurations. The serving cell ID refers to the cell that controls the NCR-Fwd 510A and is forwarded by the NCR-Fwd 510A. Therefore, it is preferable that the cell ID that controls the NCR-Fwd 510A can be optionally set in each entry of the "ToAddModList" in the NCR configuration information.

(1.4.2) Example of Operation According to First Embodiment Taking the above discussion into consideration, the operation according to the first embodiment will be described. Fig. 18 is a diagram showing NCR setting information in the ToAddMod list format according to the first embodiment.

The communication method according to the first embodiment is a method used in an NCR device 500A having a plurality of NCR-Fwds 510A, each of which performs relay operations to relay radio signals transmitted between a network 5 and a UE 100, and an NCR-MT 520A that receives an NCR control signal from the network 5 for use in controlling the plurality of NCR-Fwds 510A. First, the NCR-MT 520A receives an NCR control signal (e.g., an RRC Reconfiguration message) from a gNB 200 that includes NCR setting information in a list format (i.e., NCR setting information in a ToAddMod list format) having a group of setting parameters associated with the NCR-Fwd 510A as an entry, and holds the NCR setting information. Secondly, the NCR device 500A (NCR-MT 520A) controls each of the multiple NCR-Fwds 510A using a set of configuration parameters for the corresponding entries in the NCR configuration information.

In this way, by introducing NCR setting information in the form of a ToAddMod list (also referred to as "NCR-ToAddModList"), it is possible to efficiently configure each NCR-Fwd 510A under the assumption that one NCR-MT 520A can handle multiple NCR-Fwds 510A. Specifically, in the NCR-ToAddModList, one entry corresponds to one NCR-Fwd 510A (see Figure 15). In the example of Figure 15, the NCR-ToAddModList has three entries (NCR-ToAddMod #1 to NCR-ToAddMod #3). NCR-ToAddMod#1 to NCR-ToAddMod#3 in the NCR-ToAddModList correspond to NCR-Fwd510A#1 to NCR-Fwd510A#3 of the NCR device 500A, respectively.

Each entry in the NCR-ToAddModList contains an identifier for that entry. In the example of FIG. 18, that identifier is a setting ID. However, instead of the setting ID, an NCR-Fwd index or a setting entry index may be used. The identifier (setting ID) is used to identify the entry when deleting, changing, or adding an entry (setting parameter group).

When deleting an entry, NCR-MT520A receives an NCR control signal (e.g., an RRC Reconfiguration message) from gNB200 that includes a ToReleaseList, which is a list of the configuration IDs of the entries to be deleted. If an entry having a configuration ID in the ToReleaseList is included in the NCR configuration information held by NCR-MT520A, NCR-MT520A deletes the entry from the NCR configuration information it holds.

When changing an entry, NCR-MT520A receives an NCR-ToAddModList including an entry with a setting ID from gNB200. If NCR-MT520A holds an entry with that setting ID, it changes the setting content of the entry it holds using the content of that entry in the received ToAddModList.

When adding an entry, NCR-MT520A receives from gNB200 an NCR-ToAddModList that includes an entry with a setting ID that it does not yet hold. NCR-MT520A determines that it does not yet hold an entry with that setting ID, and adds a new entry and setting contents with the contents of that entry in the received ToAddModList (i.e., adds a new entry).

Each entry of the NCR-ToAddModList may include an RNTI assigned to the corresponding NCR-Fwd 510A by the network 5. The RNTI is an RNTI dedicated to the NCR device and is also referred to as the NCR-RNTI. The corresponding RNTI may be assigned individually to each NCR-Fwd 510A. By including the NCR-RNTI in each entry of the NCR-ToAddModList, the NCR-RNTI can be associated with the NCR-Fwd 510A. For example, when the NCR-MT 520A receives an SCI from the gNB 200, it can determine which NCR-Fwd 510A the SCI is for based on the NCR-RNTI used to receive (blind decode) the SCI.

Each entry in the NCR-ToAddModList may include various setting information related to the relay operation settings of the corresponding NCR-Fwd 510A. As described above, the various setting information may include at least one of setting information related to the on/off status of the NCR-Fwd 510A, frequency information specifying the frequency (or band) to be relayed, mode information specifying the operation mode of the NCR-Fwd 510A, beam information specifying the beam pattern, etc., of the NCR-Fwd 510A, and transmission power information for controlling the transmission power of the NCR-Fwd 510A. Here, the frequency information may be information on the center frequency and the bandwidth. The frequency information may be information on the lower limit frequency and the upper limit frequency.

The various setting information of each entry may include information about periodic beams (periodic beam indication). The information may include at least one of information specifying a slot, information specifying a beam (weight) for each slot, and repetition information (e.g., how many slots to repeat, up to how many slots to repeat, etc.).

The various setting information of each entry may include information regarding the setting of intermittent reception (intermittent relay) of the corresponding NCR-Fwd 510A. The information may include at least one of information indicating the length of the on-period during which the NCR-Fwd 510A relays, information indicating the period (cycle) of the on-period, and information indicating the time for which the NCR-Fwd 510A should remain on if it receives (relays) a wireless signal during the on-period.

The various setting information of each entry may include information regarding the setting of intermittent reception for SCI reception of the corresponding NCR-Fwd 510A. The information may include at least one of information indicating the time length of the on-period during which the NCR-MT 520A performs SCI reception operation, information indicating the period (cycle) of the on-period, and information indicating the time for which the on-period should continue if the NCR-MT 520A receives a control signal (SCI or PDCCH) during the on-period. During the on-period, the NCR-MT 520A may perform reception processing of the corresponding RNTI (in the same entry). For example, during the on-period associated with a certain NCR-Fwd 510A, the NCR-MT 520A may perform PDCCH monitoring (blind decoding) using the NCR-RNTI assigned to the NCR-Fwd 510A.

In addition, the various setting information for each entry may include information linking the on-period to a separately set intermittent reception setting instead of the on-period time length, cycle, and on-period duration information. The separately set intermittent reception setting (list) includes information on the on-period time length, cycle, and on-period duration, and an intermittent reception setting index. The linking information may specify the intermittent reception setting by the index (i.e., act as a pointer). In this way, by setting the intermittent reception setting as a separate setting (list), it is no longer necessary to set the on-period time length, cycle, and on-period duration information each time in each entry of the NCR-ToAddModList, which has the effect of reducing overhead of control signals.

The various setting information of each entry may include a failure setting described in a first modified example of the second embodiment described below. The various setting information of each entry may include a threshold value (specifically, a threshold value to be compared with wireless quality) described in a second modified example of the second embodiment described below. The various setting information of each entry may include information indicating a group to which the corresponding NCR-Fwd 510A belongs, or information indicating whether the corresponding NCR-Fwd 510A is a target for summation, as described in a third embodiment described below.

Each entry in the NCR-ToAddModList may include a unique identifier (NCR-Fwd unique management number) that is preset in the corresponding NCR-Fwd 510A. For example, the operator of the network 5 (OAM: Operations Administration and Management) sets the unique management number of the NCR-Fwd 510A in the gNB 200 together with information on the characteristics (capability) of each NCR-Fwd 510A installed in the NCR device 500A. The unique management number may also be written in advance (for example, at the time of shipment from the factory) in the memory of the NCR device 500A. The unique management number may also be set in the NCR device 500A by the OAM. The unique management number may be an identifier that is linked to the hardware of the NCR-Fwd 510A installed in the NCR device 500A (i.e., that specifies the hardware). The NCR-MT 520A may control the NCR-Fwd 510A (hardware) specified by the unique identification number in accordance with the settings of the entry.

Each entry in the NCR-ToAddModList may include the cell identifier (cell ID) of the cell for which the corresponding NCR-Fwd 510A is to perform relay operations. This makes it possible to specify which cell's signal is to be relayed by which NCR-Fwd 510A (the settings of which NCR-Fwd 510A).

FIG. 19 is a diagram showing an example of operation according to the first embodiment. In the illustrated example, an example is shown in which an NCR device 500A has three NCR-Fwds 510A (NCR-Fwds 510A#1 to NCR-Fwds 510A#3). However, the NCR device 500A may have only one or two NCR-Fwds 510A. The NCR device 500A may have four or more NCR-Fwds 510A.

In step S101, NCR-MT520A establishes an RRC connection with gNB200.

In step S102, the NCR-MT 520A in the RRC connected state may transmit a capability notification (UE Capability) indicating that it supports multiple NCR-Fwds 510A (configurations) to the gNB 200 via RRC signaling.

In step S103, gNB200 transmits NCR setting information in the form of a ToAddMod list (NCR-ToAddModList) to NCR-MT520A by RRC signaling (e.g., RRC Reconfiguration message). NCR-MT520A in the RRC connected state receives NCR-ToAddModList.

In step S104, the NCR device 500A (NCR-MT 520A) controls each of NCR-Fwd 510A#1 to NCR-Fwd 510A#3 using the set parameter group of the corresponding entry in the set NCR-ToAddModList. Also, in step S104, the NCR-MT 520A may link the RNTI set in each entry with NCR-Fwd 510A#1 to NCR-Fwd 510A#3. The NCR-MT 520A may perform reception processing (PDCCH monitoring) of the corresponding RNTI based on the discontinuous reception setting set in each entry.

(2) Second embodiment The second embodiment will be described mainly with respect to differences from the first embodiment. The second embodiment may be implemented in combination with the first embodiment.

As described above, after detecting an RLF, NCR-MT 520A turns off NCR-Fwd 510A during the RRC connection re-establishment procedure. However, assuming that NCR-MT 520A handles multiple NCR-Fwd 510A, there is a problem in that it is unclear how to control NCR-Fwd 510A.

The communication method according to the second embodiment is a method used by an NCR device 500A having multiple NCR-Fwds 510A, each of which performs relay operations to relay wireless signals transmitted between a network 5 and a UE 100, and an NCR-MT 520A that receives an NCR control signal from the network 5 used to control the multiple NCR-Fwds 510A. First, the NCR-MT 520A detects deterioration of wireless quality in wireless communication with the network 5. Second, the NCR device 500A (NCR-MT 520A) performs off control to control at least one of the multiple NCR-Fwds 510A to be off based on the detection of the deterioration of wireless quality.

In the second embodiment, detecting deterioration of wireless quality in wireless communication with the network 5 includes detecting an RLF with the network 5. Furthermore, performing off control may be controlling all NCR-Fwds 510A handled by the NCR-MT 520A to be off. That is, the NCR device 500A (NCR-MT 520A) according to the second embodiment controls all NCR-Fwds 510A handled by the NCR-MT 520A to be off based on the detection of an RLF.

Specifically, NCR-MT520A detects (declares) an RLF if the wireless problem is not resolved by the time a first timer (e.g., timer T310) expires after detecting it. When NCR-MT520A detects an RLF, it starts a second timer (e.g., timer T311) and attempts cell selection and RRC connection re-establishment while the second timer is running. If the RRC connection re-establishment is not successful by the time the second timer expires, NCR-MT520A transitions to the RRC idle state.

In the second embodiment, the NCR-MT 520A may control all NCR-Fwds 510A to be turned off when the RRC connection re-establishment procedure is started, when a suitable cell that satisfies a predetermined wireless quality standard cannot be selected (discovered) by cell selection, or when the RRC state is transitioned to idle.

FIG. 20 is a diagram showing an example of operation according to the second embodiment. Here, it is assumed that the NCR device 500A has multiple NCR-Fwds 510A and controls the multiple NCR-Fwds 510A according to an NCR control signal including multiple settings (and controls) from the gNB 200.

In step S201, the NCR-MT 520A in the RRC connected state detects an RLF. Note that at least one NCR-Fwd 510A is in the ON state before detecting the RLF. Even if the NCR-MT 520A detects an RLF, it may still hold the last received NCR control signal (multiple settings (and controls)), i.e., the most recent NCR control signal.

In step S202, NCR-MT 520A performs cell selection and RRC connection re-establishment procedures. Specifically, NCR-MT 520A performs cell selection and transmits an RRC re-establishment request message to the cell selected in the cell selection. If NCR-MT 520A receives an RRC re-establishment message from the cell before the second timer expires, it may determine that the RRC connection re-establishment has been successful.

Here, the NCR device 500A (NCR-MT 520A) controls all NCR-Fwds 510A to be turned off during the RRC connection re-establishment procedure. The NCR device 500A (NCR-MT 520A) may control all NCR-Fwds 510A to be turned off when the RRC connection re-establishment procedure is started or when a suitable cell cannot be selected (discovered) by cell selection.

In step S203, NCR-MT 520A determines whether or not the RRC connection re-establishment was successful. If it is determined that the RRC connection re-establishment failed (step S203: NO), NCR-MT 520A transitions to the RRC idle state (step S204). In this case, NCR-MT 520A may discard the latest NCR control signal that it holds.

On the other hand, if it is determined that the RRC connection has been successfully re-established (step S203: YES), the NCR-MT 520A may resume control of the multiple NCR-Fwds 510A based on the latest NCR control signal. For example, the NCR-MT 520A may control at least one NCR-Fwd 510A to be on based on the latest NCR control signal. Such an operation may be performed only when the cell at the time of the RLF occurrence and the cell where the RRC connection has been re-established are the same.

(2.1) First Modification of Second Embodiment A first modification of the second embodiment will be described, focusing mainly on the differences from the above-described second embodiment.

In this modified example, the NCR-Fwd 510A to be controlled to be turned off after an RLF according to the second embodiment can be set to the NCR-MT 520A from the network 5 (gNB 200). That is, in this modified example, the NCR-MT 520A receives setting information (also called "failure setting") for specifying the NCR-Fwd 510A to be controlled to be turned off after an RLF from the network 5 (gNB 200), and controls to turn off the NCR-Fwd 510A specified based on the failure setting among the multiple NCR-Fwds 510A.

The fault setting may be information that sets how to control each NCR-Fwd 510A when an RLF occurs in the NCR-MT 520A. The fault setting may be set individually for each NCR-Fwd 510A. For example, each entry of the above-mentioned NCR-ToAddModList may include a fault setting. The fault setting may be information that specifies the operation of the corresponding NCR-Fwd 510A when an RLF occurs in the NCR-MT 520A, either "continue to control on," "control to off," or "operate as a conventional RF repeater without network control." When operating as a conventional RF repeater without network control, the NCR device 500A (NCR-Fwd 510A) may perform implementation-dependent beamforming, etc.

FIG. 21 is a diagram showing an example of operation according to a first modified example of the second embodiment. Here, it is assumed that the NCR device 500A has multiple NCR-Fwds 510A and controls the multiple NCR-Fwds 510A according to an NCR control signal including multiple settings (and controls) from the gNB 200. Duplicate explanations of operations that are the same as those in the second embodiment described above will be omitted.

In step S211, the NCR-MT 520A in the RRC connected state receives an NCR control signal (e.g., an RRC Reconfiguration message) including the failure settings of each NCR-Fwd 510A from the gNB 200.

In step S212, NCR-MT520A in the RRC connected state detects an RLF.

In step S213, NCR-MT 520A performs cell selection and RRC connection re-establishment procedures. Here, NCR device 500A (NCR-MT 520A) controls each NCR-Fwd 510A according to the failure setting during the RRC connection re-establishment procedure. All NCR-Fwds 510A are controlled to be off. NCR device 500A (NCR-MT 520A) may control each NCR-Fwd 510A according to the failure setting when starting the RRC connection re-establishment procedure or when a suitable cell cannot be selected (discovered) by cell selection.

In step S214, the NCR-MT 520A determines whether the RRC connection re-establishment was successful. If it is determined that the RRC connection re-establishment failed (step S214: NO), the NCR-MT 520A transitions to an RRC idle state (step S215). When the NCR device 500A (NCR-MT 520A) transitions to the RRC idle state (step S215), it may control each NCR-Fwd 510A according to the failure time settings.

On the other hand, if it is determined that the RRC connection has been successfully re-established (step S214: YES), in step S216, the NCR-MT 520A may resume control of the multiple NCR-Fwds 510A based on the latest NCR control signal.

(2.2) Second Modification of Second Embodiment The second modification of the second embodiment will be described mainly with respect to the differences from the above-described second embodiment and its modifications. Fig. 22 is a diagram for explaining the operation of the second modification of the second embodiment.

In this modified example, each NCR-Fwd 510A performs relay operations with a different cell (which may be a "frequency (band)") as the relay target. In the illustrated example, NCR-Fwd 510A#1 relays the radio signal of cell #1, NCR-Fwd 510A#2 relays the radio signal of cell #2, and NCR-Fwd 510A#3 relays the radio signal of cell #3. Note that one UE 100 is associated with one cell, but in the case of CA/DC, one UE 100 may be associated with multiple cells.

NCR-MT520A has multiple receivers (which may be multiple transceivers) for receiving radio signals of each cell (each frequency) and monitors (measures) the radio quality of each cell (each frequency). The radio quality may be at least one of RSRP, RSRQ, and SINR. Any of cells #1 to #3 may be the serving cell (PCell) of NCR-MT520A.

Thus, in this modified example, the NCR-MT 520A measures wireless quality using the cells or frequencies relayed by each NCR-Fwd 510A handled by the NCR-MT 520A as the measurement target. The NCR device 500A (NCR-MT 520A) then controls to turn off the NCR-Fwd 510A corresponding to the measurement target for which the measurement result falls below the threshold. For example, if the measurement result for cell #1 falls below the threshold, the NCR device 500A (NCR-MT 520A) controls to turn off the NCR-Fwd 510A#1 corresponding to cell #1. For example, if the measurement result for cell #2 is not below the threshold, the NCR device 500A (NCR-MT 520A) keeps the NCR-Fwd 510A#2 corresponding to cell #2 on. Note that when the measurement result falls below the threshold, it may mean that RLF is detected.

FIG. 23 is a diagram showing an example of operation according to the second modification of the second embodiment. Here, it is assumed that the NCR device 500A has multiple NCR-Fwds 510A and controls the multiple NCR-Fwds 510A according to an NCR control signal including multiple settings (and controls) from the gNB 200. Duplicate explanations of operations that are the same as those in the second embodiment and its modification described above will be omitted.

In step S221, the NCR-MT 520A in the RRC connected state may receive an NCR control signal (e.g., an RRC Reconfiguration message) from the gNB 200, which includes a threshold setting for each NCR-Fwd 510A (each cell or each frequency). For example, each entry in the above-mentioned NCR-ToAddModList may include a threshold setting. The threshold may be at least one of an RSRP threshold, an RSRQ threshold, and an SINR threshold.

In step S222, NCR-MT 520A in the RRC connected state may detect an RLF for the PCell. In this case, NCR-MT 520A may perform cell selection and RRC connection re-establishment procedures. The threshold determination in step S224 described below may be performed using the RLF of the PCell as a trigger. The threshold determination in step S224 described below may be performed when NCR-MT 520A starts the RRC connection re-establishment procedure or when NCR-MT 520A is unable to select (find) a suitable cell through cell selection.

In step S223, NCR-MT 520A monitors (measures) the wireless quality of each cell. For example, the receiver of NCR-MT 520A associated with each NCR-Fwd 510A monitors the wireless quality of the cell relayed by each NCR-Fwd 510A.

In step S224, NCR-MT520A determines whether the wireless quality of each cell has fallen below a threshold.

If the wireless quality of the cell is not below the threshold (step S224: NO), in step S225, the NCR device 500A (NCR-MT 520A) controls the NCR-Fwd 510A that relays the cell to be on (specifically, controls it according to the current settings).

On the other hand, if the wireless quality of the cell falls below the threshold (step S224: YES), in step S226, the NCR device 500A (NCR-MT 520A) controls the NCR-Fwd 510A that relays the cell to be turned off. When the NCR-MT 520A turns off the NCR-Fwd 510A, the NCR-MT 520A may notify the gNB 200. The notification may include information for identifying the turned-off NCR-Fwd 510A (the above-mentioned setting ID, frequency information, cell ID, NCR-RNTI, and/or NCR-Fwd unique identifier). The notification may be performed by RRC signaling (e.g., a UE Assistance Information message).

(2.3) Third Modification of Second Embodiment The third modification of the second embodiment will be described below, focusing on the differences from the second embodiment and the modifications. This modification is an example assuming CA/DC.

NCR-MT520A is configured with CA by gNB200. In CA, multiple component carriers (CCs) corresponding to multiple serving cells are aggregated, and NCR-MT520A can receive or transmit simultaneously on multiple CCs (multiple cells). The multiple CCs may be contiguous in the frequency direction. The multiple CCs may be discontinuous. When CA is configured, NCR-MT520A has only one RRC connection with network 5 (e.g., gNB200). One serving cell is called a primary cell (PCell). A set of serving cells can be formed by configuring a secondary cell (SCell) together with a PCell in NCR-MT520A. Thus, the set of serving cells configured in NCR-MT520A consists of one PCell and one or more SCells. SCell reconfiguration, addition, and deletion can be performed by RRC.

FIG. 24 is a diagram for explaining the DC. In the DC, the NCR-MT 520A communicates with the master cell group (MCG) 201M managed by the master node (MN) 200M and the secondary cell group (SCG) 201S managed by the secondary node (SN) 200S. The MN 200M and the SN 200S are connected to each other via a network interface (specifically, an inter-base station interface). The network interface may be an Xn interface or an X2 interface. Both the MN 200M and the SN 200S may be gNBs 200.

For example, DC is initiated when MN200M sends a specific message (e.g., an SN Addition Request message) to SN200S, and MN200M sends an RRC Reconfiguration message to NCR-MT520A. In DC, NCR-MT520A in the RRC connected state is assigned radio resources by the respective schedulers of MN200M and SN200S, and performs wireless communication using the radio resources of MN200M and the radio resources of SN200S.

MN200M may have a control plane connection with the core network. MN200M provides the primary radio resources for NCR-MT520A. MN200M manages MCG201M. MCG201M is a group of serving cells associated with MN200M. MCG201M has a primary cell (PCell) and optionally has one or more secondary cells (SCell). On the other hand, SN200S may not have a control plane connection with the core network. SN200S provides additional radio resources to NCR-MT520A. SN200S manages SCG201S. SCG201S has a primary/secondary cell (PSCell) and optionally has one or more SCells. In addition, the PCell of MCG201M and the PSCell of SCG201S are sometimes referred to as special cells (SpCells).

If NCR-MT520A detects an RLF for the MCG (MCG PCell), it may perform a Fast MCG Recovery operation. In the Fast MCG Recovery operation, NCR-MT520A notifies MN200M of the RLF via SN200S. MN200M notifies NCR-MT520A of RRC reconfiguration information via SN200S. If the Fast MCG Recovery operation is successful, NCR-MT520A can continue wireless communication with the MCG.

FIG. 25 is a diagram for explaining the operation of the third modified example of the second embodiment.

In the case of CA/DC setting (especially in the case of interband), the operating frequency of each cell and NCR-Fwd510A must match, so NCR-MT520A must also be set to CA/DC. In the illustrated example, the MCG PCell of NCR-MT520A is relayed by NCR-Fwd510A#1, the MCG SCell of NCR-MT520A is relayed by NCR-Fwd510A#2, the SCG PSCell of NCR-MT520A is relayed by NCR-Fwd510A#3, and the SCG SCell of NCR-MT520A is relayed by NCR-Fwd510A#4. Note that one UE100 is associated with one cell, but in the case of CA/DC, one UE100 may be associated with multiple cells. The PCell/PSCell/SCell of NCR-MT520A and the PCell/PSCell/SCell of UE100 may be different cells, or may simply have the same frequency relationship.

Here, in the case of CA/DC, the targets for which NCR-MT520A performs RLM (RLF monitoring) are only PCell and PSCell. It is considered that SCell will not communicate when PCell/PSCell is RLF for each cell group (CG). However, considering NCR device 500A, it is also possible to consider operation in which relaying of SCell continues even if PCell/PSCell is RLF. In other words, even if PCell/PSCell is RLF and SCell communication with NCR-MT520A is interrupted, communication between gNB200 and UE100 continues. Since NCR-Fwd510A can continue to be on with the latest settings even without real-time control, there may be cases where it is better to continue relaying operation when considering communication between gNB200 and UE100. Also, when the Fast MCG Recovery operation is successful, it is considered appropriate to keep the NCR-Fwd510A in the on position.

In this modified example, multiple NCR-Fwds 510A perform relay operations for different cells and/or different cell groups. The NCR device 500A (NCR-MT 520A) determines which NCR-Fwd 510A to control to off in response to detection of deterioration in wireless quality for the primary cell (PCell/PSCell). For example, in the case of CA/DC, even if the PCell/PSCell becomes RLF, the NCR device 500A (NCR-MT 520A) controls the NCR-Fwd 510A based on the latest settings (does not turn it off) under certain conditions.

FIG. 26 is a diagram showing an example of operation according to a third modified example of the second embodiment. Here, it is assumed that the NCR device 500A has multiple NCR-Fwds 510A and controls the multiple NCR-Fwds 510A according to an NCR control signal including multiple settings (and controls) from the gNB 200. It is also assumed that CA/DC is set in the NCR-MT 520A. Duplicate explanations of operations that are the same as those in the second embodiment and its modified examples described above will be omitted.

In step S231, NCR-MT520A, which is in the RRC connected state, detects RLF in the primary cell (PCell/PSCell).

In step S232, NCR-MT 520A determines whether it has detected an RLF for the SCG (PSCell) or for the MCG (PCell). If it has detected an RLF for the SCG (PSCell) (step S232: YES), in step S233, NCR-MT 520A sends an SCG Failure Indication to the MCG (MN200M). In addition, NCR-MT 520A turns off NCR-Fwd 510A, which relays the PSCell of the SCG. However, the NCR device 500A (NCR-MT520A) continues relay control of the NCR-Fwd510A that relays the MCG and the NCR-Fwd510A that relays the SCG SCell with the latest settings (and control) (i.e., keeps it on).

On the other hand, if an RLF is detected for the MCG (PCell) (step S232: NO), in step S234, NCR-MT 520A determines whether or not Fast MCG Recovery was successful. When the Fast MCG Recovery procedure is started, NCR-MT 520A sends an MCG Failure Indication to the MCG (MN 200M) via the SCG (SN 200S). During the Fast MCG Recovery procedure and if Fast MCG Recovery is successful, NCR-MT 520A continues relay control of NCR-Fwd 510A, which relays the MCG and SCG (i.e., all cells), with the latest settings (and control).

If Fast MCG Recovery is not performed or if Fast MCG Recovery fails (step S234: NO), in step S235, NCR-MT 520A performs cell selection and RRC connection re-establishment procedures. In this case, NCR device 500A (NCR-MT 520A) turns off NCR-Fwd 510A that relays the MCG PCell. However, NCR-MT 520A continues relay control of NCR-Fwd 510A that relays the MCG SCell and NCR-Fwd 510A that relays the SCG with the latest settings (and control).

In step S236, NCR-MT 520A determines whether the RRC connection has been successfully re-established (i.e., the RLF has been resolved). If the RRC connection has been successfully re-established (step S236: YES), in step S237, NCR device 500A (NCR-MT 520A) may resume control of NCR-Fwd 510A, for which relay control has been turned off, based on the latest settings (and control). Alternatively, NCR device 500A (NCR-MT 520A) may control NCR-Fwd 510A based on new settings (and control) from gNB 200.

On the other hand, if re-establishment of the RRC connection fails (step S236: NO), in step S238, the NCR-MT 520A transitions to the RRC idle state. In this case, the NCR device 500A (NCR-MT 520A) may control all NCR-Fwds 510A to be turned off.

(3) Third embodiment The third embodiment will be described mainly with respect to the differences from the above-mentioned embodiments. The third embodiment may be implemented in combination with the above-mentioned embodiments.

Generally, in order to prevent interference and the like, an upper limit on transmission power (also called "maximum transmission power") is specified for wireless communication devices used in the mobile communication system 1. Here, when the NCR device 500A has multiple NCR-MTs 520A, there is a problem in that it is unclear how to specify the transmission power of the NCR device 500A.

In the third embodiment, when the NCR device 500A has multiple NCR-MTs 520A, the sum of the transmission powers of the multiple NCR-MTs 520A is defined as the transmission power of the NCR device 500A. In particular, when the NCR device 500A performs subband operation, multiple NCR-Fwds 510A relay one system band, so it is desirable to define the total transmission power of the multiple NCR-Fwds 510A as the transmission power of the NCR device 500A.

Figure 27 is a diagram for explaining an example of operation according to the third embodiment. The operation (communication method) according to the third embodiment is a method used in an NCR device 500A having multiple NCR-Fwds 510A, each of which performs relay operations to relay radio signals transmitted between a network 5 and a UE 100, and an NCR-MT 520A that receives an NCR control signal from the network 5 for use in controlling the multiple NCR-Fwds 510A. In step S301, the NCR device 500A (NCR-MT 520A) identifies the total transmission power for the multiple NCR-Fwds 510A of the NCR device 500A. In step S302, the NCR device 500A (NCR-MT 520A) sets and/or controls the multiple NCR-Fwds 510A of the NCR device 500A so that the total transmission power identified in step S301 does not exceed the maximum transmission power determined for the NCR device 500A.

For example, gNB200 configures multiple NCR-Fwds 510A for NCR-MT520A. NCR device 500A (NCR-MT520A) controls the transmission power (and/or amplification gain) of each NCR-Fwd 510A so that the sum of the transmission powers of the multiple NCR-Fwds 510A matches (or falls below) the maximum transmission power regulation. Note that the maximum transmission power may be a fixed value defined in the 3GPP technical specifications. The maximum transmission power may also be a variable value that can be set from gNB200 to NCR-MT520A.

The total transmission power may be the sum of the transmission power of all NCR-Fwds 510A included in the NCR device 500A. In other words, the sum covers all NCR-Fwds 510A associated with one NCR device 500A (one NCR-MT 520A).

The multiple NCR-Fwds 510A of the NCR device 500A may be divided into multiple groups. In step S302, the total transmission power may be determined for each of the multiple groups. In step S302, the multiple NCR-Fwds 510A may be set and/or controlled so that the total transmission power of each of the multiple groups does not exceed the maximum transmission power.

Here, in grouping, multiple NCR-Fwds 510A may be grouped into multiple groups according to the cells to be relayed. For example, when using subband operation to relay the radio signal of one cell by dividing the frequency among multiple NCR-Fwds 510A, the multiple NCR-Fwds 510A relaying the radio signal of that one cell are included in the total. In other words, NCR-Fwds 510A transmitting other cells are not included (are included in a different total).

Alternatively, multiple NCR-Fwds 510A may be grouped into multiple groups according to the cell groups to be relayed. For example, when CA/DC is being performed, multiple NCR-Fwds 510A that relay radio signals of the PCell (PSCell) and SCell of one cell group are the total targets. In other words, the MCG and SCG are separate total targets.

Alternatively, multiple NCR-Fwds 510A may be grouped into multiple groups according to the frequency band to be relayed. For example, when band n257 (26.5 to 29.5 GHz) is relayed by multiple NCR-Fwds 510A, the multiple NCR-Fwds 510A relaying the wireless signals of that band are included in the total. In other words, NCR-Fwds 510A transmitting other bands are not included (are included in a different total).

The network 5 (e.g., gNB 200) may transmit to the NCR device 500A (NCR-MT 520A) setting information for specifying a group of NCR-Fwd 510A to be totaled. The NCR device 500A (NCR-MT 520A) may receive setting information for specifying a group of NCR-Fwd 510A to be totaled from the network 5. In step S301, the total transmission power for the specified group may be determined based on the setting information. Here, the setting information may be information indicating the frequency range to be totaled. For example, an upper and/or lower limit frequency is specified (set), and multiple NCR-Fwd 510A included in the band defined by the upper and/or lower limit frequency are to be totaled. Alternatively, the setting information may be a combination of identifiers of the NCR-Fwd 510A. For example, multiple NCR-Fwds 510A of a set of identifiers specified using the NCR-Fwd 510A identifier (or the RRC setting index (setting ID)) are the target of the summation.

In the third embodiment, the total transmission power may be the total transmission power in the downlink (downlink access link). Also, the maximum transmission power may be the maximum transmission power in the downlink (downlink access link). That is, in step S302, the NCR device 500A (NCR-MT 520A) may set and/or control the multiple NCR-Fwds 510A of the NCR device 500A so that the total transmission power of the downlink does not exceed the maximum transmission power of the downlink.

In the third embodiment, the total transmission power may be the total transmission power in the uplink (uplink backhaul link). The maximum transmission power may be the maximum transmission power in the uplink (uplink backhaul link). That is, in step S302, the NCR device 500A (NCR-MT 520A) may set and/or control the multiple NCR-Fwds 510A of the NCR device 500A so that the total transmission power in the uplink does not exceed the maximum transmission power in the uplink.

(4) Fourth embodiment Next, the fourth embodiment will be described, focusing mainly on the differences from the above-mentioned embodiments. As shown in Fig. 28, the relay device according to the fourth embodiment is a RIS (Reconfigurable Intelligent Surface) device 500B that changes the propagation direction of an incident radio wave (wireless signal) by reflection or refraction. "NCR" in the above-mentioned embodiments can be read as "RIS".

RIS is a type of repeater (hereinafter also referred to as "RIS-Fwd") that can perform beamforming (directivity control) in the same way as NCR by changing the properties of the metamaterial. 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, it may be configured to control the reflection direction and/or refraction direction of each unit element and to focus (direct the beam) on a nearby UE or a distant UE.

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 the incident radio waves by reflecting the radio waves. Here, the reflection angle of the radio waves can be variably set. The RIS-Fwd 510B reflects the 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 can be variably set.

FIG. 29 is a diagram showing an example of the configuration of a RIS-Fwd (repeater) 510B and a RIS-MT (control terminal) 520B according to the fourth embodiment. The RIS-MT 520B has a receiver 521, a transmitter 522, and a controller 523. This configuration is similar to that of the above-mentioned embodiment. The RIS-Fwd 510B has a RIS 511B and a RIS controller 512B. The RIS 511B is a metasurface made of a metamaterial. For example, the RIS 511B is made by arranging very small structures in an array relative to the wavelength of radio waves, and by making the structures have different shapes depending on the arrangement location, it is possible to arbitrarily design the direction and/or beam shape of the reflected wave. The RIS 511B may be a transparent dynamic metasurface. RIS511B is configured by overlaying a transparent glass substrate on a transparent metasurface substrate on which a large number of small structures are regularly arranged, and by minutely 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. RIS control unit 512B controls RIS511B in response to a RIS control signal from control unit 523 of RIS-MT520B. RIS control unit 512B may include at least one processor and at least one actuator. The processor decodes the RIS control signal from control unit 523 of RIS-MT520B and drives the actuator in response to the RIS control signal.

(4.1) Modification of the Fourth Embodiment In this modification, a scenario is assumed in which one relay device (one MT) is associated with at least one NCR-Fwd 510A and at least one RIS-Fwd 510B. That is, one relay device (one MT) is associated with two types of relays (Fwd). FIG. 30 is a diagram for explaining a modification of the fourth embodiment.

In this modified example, the relay device 500C has an MT 520C, an NCR-Fwd 510A, and a RIS-Fwd 510B. RIS and NCR have many things in common, but the format of the side control information (SCI) transmitted from the gNB 200 to the MT 520C over the control link is expected to be different.

Currently, in 3GPP, it has been agreed that the CRC bits of the PDCCH carrying the SCI for NCR-Fwd 510A will be scrambled by a newly introduced dedicated RNTI (also referred to as "NCR-RNTI"). In this modified example, the CRC bits of the PDCCH carrying the SCI for RIS-Fwd 510B will be scrambled by a newly introduced dedicated RNTI (also referred to as "RIS-RNTI"). Here, the RNTI for RIS and the RNTI for NCR are different values.

Under these assumptions, relay device 500C (MT520C) identifies the SCI format by the RNTI. Specifically, the communication method according to this modified example is a method used by relay device 500C having multiple Fwds (repeaters) each performing a relay operation to relay radio signals transmitted between network 5 and UE 100, and MT520C (control terminal) that receives control signals from network 5 used to control the multiple Fwds. First, the MT 520C monitors the PDCCH (specifically, performs blind decoding of the PDCCH/SCI) using a first RNTI (e.g., NCR-RNTI) assigned to a first type Fwd (e.g., NCR-Fwd 510A) among the multiple Fwds and a second RNTI (e.g., RIS-RNTI) assigned to a second type Fwd (e.g., RIS-Fwd 510B) among the multiple Fwds. Second, when the relay device 500C (MT 520C) successfully decodes SCI (control information) on the PDCCH using either the first RNTI or the second RNTI, it controls the type of Fwd corresponding to the RNTI used for the decoding based on the SCI. In this way, the MT 520C determines the SCI format for RIS/NCR from the RNTI of the received SCI.

FIG. 31 shows an example of the operation of a modified example of the fourth embodiment.

In step S401, MT520C receives NCR setting information (including NCR-RNTI) and RIS setting information (including RIS-RNTI) from gNB200. Here, the NCR-RNTI value and the RIS-RNTI value are assumed to be different values. Note that MT520C may be assigned a separate C-RNTI.

In step S402, MT520C monitors the PDCCH (SCI) from gNB200. Here, MT520C attempts to decode the PDCCH (SCI) using the NCR-RNTI and RIS-RNTI. Specifically, MT520C performs blind decoding of the PDCCH using each of the NCR-RNTI and RIS-RNTI, and obtains the SCI that has been successfully decoded. Here, it is assumed that the PDCCH (SCI) has been successfully decoded (step S403).

If the PDCCH decoding is successful using the NCR-RNTI (step S404: YES), in step S405, MT 520C identifies the SCI associated with the PDCCH as NCR control information. In this case, relay device 500C (MT 520C) controls NCR-Fwd 510A based on the SCI.

If the PDCCH decoding is successful with the RIS-RNTI (step S404: NO), in step S406, MT 520C identifies the SCI associated with the PDCCH as RIS control information. In this case, relay device 500C (MT 520C) controls RIS-Fwd 510C based on the SCI.

(5) Other embodiments The above-mentioned operation flows are not limited to being implemented separately and independently, but can be implemented by combining two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow. In each flow, it is not necessary to execute all steps, and only some steps may be executed.

In the above embodiment, an example in which the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB). The base station may also be a relay node such as an IAB node. The base station may be a distributed unit (DU) of the IAB node. The base station may be a DU of the IAB node. The UE 100 may also be a mobile termination (MT) of the IAB node.

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 composed of a combination of at least part of a core network device and at least part of a base station.

The functions realized by the UE100, gNB200 (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), CPUs (Central Processing Units), conventional circuits, and/or combinations thereof, programmed to realize the described functions. A processor includes transistors and other circuits and is considered to be circuitry or processing circuitry. A processor may be a programmed processor that executes a program stored in a memory. In this specification, circuitry, unit, or means is hardware that is programmed to realize the described functions, or hardware that executes them. The hardware may be any hardware disclosed herein or any hardware known to be programmed or capable of performing the described functions. If the hardware is a processor considered to be a type of circuitry, the circuitry, means, or unit is a combination of hardware and software used to configure the hardware and/or processor.

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

As used in this disclosure, the terms "based on" and "depending on/in response to" do not mean "based only on" or "only in response to" unless otherwise specified. The term "based on" means both "based only on" and "based at least in part on". Similarly, the term "in response to" means both "only in response to" and "at least in part on". The terms "include", "comprise", and variations thereof do not mean including only the recited items, but may include only the recited items or may include additional items in addition to the recited items. In addition, 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 is not intended to generally limit the quantity or order of those elements. These designations may be used herein as a convenient way to distinguish between two or more elements. Thus, a reference to a first and 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 manner. In this disclosure, where articles are added by translation, such as, for example, a, an, and the in English, these articles are intended to include the plural unless the context clearly indicates otherwise.

The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to the above, and various design changes can be made without departing from the spirit of the invention.

This application claims priority from Japanese Patent Application No. 2023-021166 (filed February 14, 2023), the entire contents of which are incorporated herein by reference.

(6) Additional Notes Additional notes will be given regarding the features of the above-described embodiment.

(Appendix 1)
A communication method for use in a relay device having a plurality of relay devices each performing a relay operation for relaying a radio signal transmitted between a network and a user device, and a control terminal receiving a control signal for controlling the plurality of relay devices from the network, the method comprising:
determining a total transmit power for the plurality of repeaters;
configuring and/or controlling the plurality of repeaters such that the total transmit power does not exceed a maximum transmit power defined for the repeater device.

(Appendix 2)
The communication method according to claim 1, wherein the total transmission power is a sum of transmission powers of all relays included in the relay device.

(Appendix 3)
The method further comprises grouping the plurality of repeaters into a plurality of groups;
the determining step includes determining the total transmit power for each of the plurality of groups;
The communication method according to claim 1, wherein the setting and/or controlling step includes a step of setting and/or controlling the plurality of repeaters so that the total transmission power of each of the plurality of groups does not exceed the maximum transmission power.

(Appendix 4)
The communication method according to claim 3, wherein the grouping step includes a step of grouping the plurality of repeaters into the plurality of groups by cell to be relayed, by cell group to be relayed, or by frequency band to be relayed.

(Appendix 5)
The method further includes a step of receiving configuration information from the network for specifying a group of repeaters to be totaled;
The communication method according to claim 1, wherein the step of specifying a total transmission power includes a step of specifying the total transmission power for the group specified based on the setting information.

(Appendix 6)
the total transmission power is the total transmission power in a downlink,
The communication method according to any one of Supplementary Notes 1 to 5, wherein the maximum transmission power is the maximum transmission power in a downlink.

(Appendix 7)
the total transmission power is the total transmission power in an uplink,
The communication method according to any one of Supplementary Notes 1 to 5, wherein the maximum transmission power is the maximum transmission power in an uplink.

(Appendix 8)
A plurality of repeaters each performing a relay operation for relaying a wireless signal transmitted between a network and a user device;
a control terminal that receives a control signal used to control the plurality of repeaters from the network;
a control unit that determines a total transmission power for the plurality of repeaters;
The control unit configures and/or controls the plurality of relays such that the total transmission power does not exceed a maximum transmission power determined for the relay device.

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

Claims (8)

A communication method for use in a relay device having a plurality of relay devices each performing a relay operation for relaying a radio signal transmitted between a network and a user device, and a control terminal receiving a control signal for controlling the plurality of relay devices from the network, the method comprising:
determining a total transmit power for the plurality of repeaters;
and configuring and/or controlling the plurality of repeaters such that the total transmit power does not exceed a maximum transmit power defined for the repeater. The communication method according to claim 1 , wherein the total transmission power is a sum of transmission powers of all relays included in the relay device. The method further comprises grouping the plurality of repeaters into a plurality of groups;
the determining includes determining the total transmit power for each of the plurality of groups;
The communication method according to claim 1 , wherein the setting and/or controlling includes setting and/or controlling the plurality of repeaters so that the total transmission power of each of the plurality of groups does not exceed the maximum transmission power. The communication method according to claim 3 , wherein the grouping comprises grouping the plurality of repeaters into the plurality of groups by a cell to be relayed, by a cell group to be relayed, or by a frequency band to be relayed. The method further includes receiving configuration information from the network for specifying a group of repeaters to be totaled;
The communication method according to claim 1 , wherein the determining the total transmission power includes determining the total transmission power for the group designated based on the setting information. the total transmission power is the total transmission power in a downlink,
The communication method according to claim 1 , wherein the maximum transmission power is the maximum transmission power in a downlink. the total transmission power is the total transmission power in an uplink,
The communication method according to claim 1 , wherein the maximum transmission power is the maximum transmission power in an uplink. A plurality of repeaters each performing a relay operation for relaying a wireless signal transmitted between a network and a user device;
a control terminal that receives a control signal used to control the plurality of repeaters from the network;
a control unit that determines a total transmission power for the plurality of repeaters;
The control unit configures and/or controls the plurality of relays such that the total transmission power does not exceed a maximum transmission power determined for the relay device.

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