Communication method, relay device, and network node

Abstract

Provided is a communication method in which is used a relay device comprising: a relay that implements a relay transmission of wireless signals between a network node and a user device; and a control terminal used for controlling the relay. The communication method comprises: a step in which the relay forms a plurality of basic beams in mutually different directions; a step in which the control terminal receives, from the network node, a beam change request for designating two or more basic beams to be coupled from among the plurality of basic beams and / or a basic beam to be split from among the plurality of basic beams; and a step in which, in response to reception of the beam change request, coupling and / or splitting of the basic beam(s) designated by the beam change request is carried out by the relay.

Description

Communication method, relay device, and network node

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

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

[0003] Radio signals (radio waves) in high frequency bands such as millimeter waves or terahertz waves have a high degree of directivity, which poses a problem of reducing the coverage of network nodes (e.g., base stations). To solve this problem, attention has been focused on repeater devices, which are a type of relay device that relays radio signals between a network node and a user device and can be controlled from the network node (see, for example, Non-Patent Document 1).

[0004] Such a repeater device can expand the coverage of a network node while suppressing interference by, for example, amplifying a radio signal received from a base station and transmitting the signal using directional transmission (beamforming). Note that such a repeater device is also called an NCR (Network-Controlled Repeater).

[0005] As another example of a relay device that performs relay transmission, a reconfigurable intelligent surface (RIS) device that changes the propagation direction of an incident radio wave (wireless signal) by reflection or refraction is also being studied. Such a RIS device may also be controllable from a network node.

[0006] 3GPP contribution: RP-213700, “New SI: Study on NR Network-controlled Repeaters”

[0007] A communication method according to a first aspect is a method using a relay device having a relay that relays radio signals between a network node and a user equipment and a control terminal used to control the relay, The communication method includes the steps of: forming a plurality of base beams in different directions by the relay; receiving, from the network node, a beam change request by the control terminal, specifying two or more base beams to be combined from the plurality of base beams and / or a base beam to be split from the plurality of base beams; and, in response to receiving the beam change request, combining and / or splitting the base beams specified in the beam change request by the relay.

[0008] A relay device according to a second aspect includes a repeater that relays radio signals between a network node and a user equipment, and a control terminal used to control the repeater. The repeater forms a plurality of base beams in different directions. The control terminal receives a beam change request from the network node, the beam change request specifying two or more base beams to combine from the plurality of base beams and / or a base beam to split from the plurality of base beams. In response to receiving the beam change request, the repeater combines and / or splits the base beams specified in the beam change request.

[0009] A network node according to a third aspect communicates with a relay device having a relay that relays radio signals transmitted between the network node and a user equipment, and a control terminal used to control the relay, wherein the network node includes a transmitter that transmits to the control terminal a beam change request that specifies two or more basic beams to be combined among a plurality of basic beams formed by the relay in different directions and / or a basic beam to be split among the plurality of basic beams.

[0010] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. FIG. 1 is a diagram illustrating a protocol stack configuration of a radio interface of a user plane that handles data. FIG. 2 is a diagram illustrating a protocol stack configuration of a radio interface of a control plane that handles signaling (control signals). FIG. 2 is a diagram illustrating an example of an application scenario of an NCR device (relay device) according to the first embodiment. FIG. 3 is a diagram illustrating an example of an application scenario of an NCR device according to the first embodiment. FIG. 4 is a diagram illustrating an example of a control method of an NCR device according to the first embodiment. FIG. 4 is a diagram illustrating an example of a configuration of a protocol stack in an NCR device according to the first embodiment. FIG. 5 is a diagram illustrating an example of a configuration of an NCR device according to the first embodiment. FIG. 6 is a diagram illustrating a configuration of a UE (user equipment) according to an embodiment. FIG. 7 is a diagram illustrating an example of a configuration of a gNB (network node) according to the first embodiment. FIG. 8 is a diagram illustrating an example of an operation scenario according to the first embodiment. FIG. 9 is a diagram illustrating an example of a basic beam of an NCR device according to the first embodiment. FIG. 10 is a diagram illustrating an example of an optimized beam of an NCR device according to the first embodiment. FIG. 11 is a diagram illustrating a basic operation of an NCR device according to the first embodiment. FIG. 12 is a diagram illustrating a first operation pattern of a mobile communication system according to the first embodiment. FIG. 13 is a diagram illustrating a second operation pattern of a mobile communication system according to the first embodiment. FIG. 14 is a diagram illustrating an example of an application scenario of a RIS device (relay device) according to the second embodiment. FIG. 15 is a diagram illustrating an example of a configuration of a RIS device according to the second embodiment.

[0011] A relay device that performs relay transmission can form multiple beams in different directions by beamforming. However, if a large number of user devices are concentrated in one beam, there is a concern that resource efficiency will decrease. Therefore, it is desirable to realize a technology that enables flexibly changing the state (beam characteristics) of the beam formed by the relay device under the control of a network node, thereby improving resource efficiency (i.e., system capacity).

[0012] Therefore, an object of the present disclosure is to flexibly change the state of the beam formed by a relay device.

[0013] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0014] (1) First Embodiment A first embodiment will be described. A relay device according to the first embodiment is a repeater device (that is, an NCR device) that can be controlled from a network.

[0015] (1.1) Overview of the Mobile Communication System First, an overview of the mobile communication system 1 according to the first embodiment will be described. Fig. 1 is a diagram showing the configuration of the mobile communication system according to the first embodiment.

[0016] The mobile communication system 1 conforms to the 5th Generation System (5GS) standard of the 3rd Generation Partnership Project (3GPP) (registered trademark; the same applies hereinafter). While the following description will be given using 5GS as an example, the mobile communication system may also be at least partially based on the Long Term Evolution (LTE) system. The mobile communication system may also be at least partially based on the 6th Generation (6G) system.

[0017] The mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN: Next Generation Radio Access Network) 10, and a 5G core network (5GC: 5G Core Network) 20. Hereinafter, the NG-RAN 10 may be simply referred to as the RAN 10. Furthermore, the 5GC 20 may be simply referred to as the core network (CN) 20. The RAN 10 and the CN 20 constitute a network 5 of the mobile communication system 1.

[0018] The UE 100 is a mobile wireless communication device. The UE 100 may be any device that is used by a user. For example, the UE 100 may be a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC, a communication module (which may be a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0019] The NG-RAN 10 includes a base station 200 (referred to as a "gNB" or "NG-RAN node" in a 5G system), which is a type of network node. The gNBs 200 are connected to each other via an Xn interface, which is an inter-node interface (inter-base station interface). The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with a UE 100 that has established a connection with its own cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, etc. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource for wireless communication with a UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0020] The gNB200 may be functionally divided into a central unit (CU) and a distributed unit (DU). The CU controls the DU. The CU is a unit including upper layers included in the protocol stack described below, such as an RRC layer, an SDAP layer, and a PDCP layer. The CU is connected to the core network via an NG interface, which is a backhaul interface. The CU is connected to neighboring base stations via an Xn interface. The DU forms a cell. The DU202 is a unit including lower layers included in the protocol stack described below, such as an RLC layer, a MAC layer, and a PHY layer. The DU is connected to the CU via an F1 interface, which is a fronthaul interface.

[0021] In addition, gNBs can also be connected to the Evolved Packet Core (EPC), which is the core network of LTE. LTE base stations can also be connected to 5GC. LTE base stations and gNBs can also be connected via an inter-base station interface.

[0022] The 5GC20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF controls data forwarding. The AMF and the UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0023] FIG. 2 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0024] The user plane radio interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0025] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of gNB200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from gNB200 on a physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires successfully decoded DCI as DCI addressed to the UE. The DCI transmitted from gNB200 has CRC (Cyclic Redundancy Code) bits scrambled by the RNTI added.

[0026] In addition, the gNB 200 transmits a synchronization signal block (SSB: Synchronization Signal / PBCH block). For example, the SSB is composed of four consecutive OFDM (Orthogonal Frequency Division Multiplex) symbols, and includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH) / master information block (MIB), and a PBCH demodulation reference signal (DMRS). The bandwidth of the SSB is, for example, 240 consecutive subcarriers, that is, a bandwidth of 20 RBs.

[0027] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the gNB 200 via a transport channel. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE 100.

[0028] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 via a logical channel.

[0029] The PDCP layer performs header compression / decompression, encryption / decryption, and the like.

[0030] The SDAP layer maps IP (Internet Protocol) flows, which are units for Quality of Service (QoS) control by the core network, to radio bearers, which are units for QoS control by the AS (Access Stratum). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0031] FIG. 3 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals).

[0032] The protocol stack of the radio interface of the control plane has an RRC (Radio Resource Control) layer and an NAS (Non-Access Stratum) layer instead of the SDAP layer shown in FIG.

[0033] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in an RRC inactive state.

[0034] The NAS layer, which is located above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the AMF 300A. Note that the UE 100 has an application layer and the like in addition to the radio interface protocol. Also, a layer lower than the NAS layer is called an AS (Access Stratum).

[0035] (1.2) Example application scenario of the relay device Next, an application scenario of the NCR device (relay device) according to the first embodiment will be described. Figures 4 and 5 are diagrams showing an example application scenario of the NCR device according to the first embodiment. Note that the NCR device may also be referred to as an NCR node.

[0036] Compared to 4G / LTE, 5G / NR enables broadband transmission using higher frequency bands. Radio signals in high frequency bands, such as the millimeter wave band or terahertz wave band, have high line-of-sight properties, which poses a challenge in reducing the coverage of the gNB 200. In FIG. 4, the UE 100 may be located outside the coverage area of ​​the gNB 200, for example, outside an area where radio signals can be received directly from the gNB 200. A shield may exist between the gNB 200 and the UE 100, preventing the UE 100 from communicating with the gNB 200 within line-of-sight.

[0037] As shown in Figure 4, an NCR device 500A, which is a type of repeater device that relays radio signals between the gNB 200 and the UE 100 and can be controlled from the network 5, is introduced into the mobile communication system 1. Such a repeater device may be referred to as a smart repeater device.

[0038] For example, the NCR device 500A amplifies a radio signal (radio wave) received from the gNB 200 and transmits it by directional transmission. Specifically, the NCR device 500A receives a radio signal transmitted by the gNB 200 by beamforming. The NCR device 500A then amplifies the received radio signal without demodulating or modulating it, and transmits the amplified radio signal by directional transmission. Here, the NCR device 500A may transmit a radio signal with a fixed directivity (beam). The NCR device 500A may also transmit a radio signal with a variable (adaptive) directional beam. This allows the coverage of the gNB 200 to be efficiently expanded.

[0039] Also, as shown in FIG. 5, a new UE (hereinafter referred to as "NCR-MT (Mobile Termination)") 100B, which is a type of control terminal for controlling the NCR device 500A, is introduced. That is, the NCR device 500A relays radio signals transmitted between the gNB 200 and the UE 100, specifically, the radio signals. NCR-Fwd (Forwarding) 510A, which is a type of repeater that changes the propagation state of the radio signal without demodulating or modulating the radio signal, and NCR-MT 520A that performs wireless communication with the gNB 200 and controls the NCR-Fwd 510A.

[0040] In this way, the NCR-MT 520A establishes a wireless connection with the gNB 200 and performs wireless communication with the gNB 200, thereby controlling the NCR device 500A in cooperation with the gNB 200. This enables efficient coverage expansion using the NCR device 500A. The NCR-MT 520A controls the NCR device 500A according to control from the gNB 200. The NCR-MT 520A also has functions similar to those of the UE 100.

[0041] The NCR-MT 520A may be configured separately from the NCR-Fwd 510A. For example, the NCR-MT 520A may be located near the NCR-Fwd 510A and electrically connected to the NCR-Fwd 510A. The NCR-MT 520A may be connected to the NCR-Fwd 510A by wire or wirelessly. Alternatively, the NCR-MT 520A may be configured integrally with the NCR-Fwd 510A. The NCR-MT 520A and the NCR-Fwd 510A may be fixedly installed, for example, at the coverage edge (cell edge) of the gNB 200 or on a wall or window of a building. The NCR-MT 520A and the NCR-Fwd 510A may be installed, for example, in a vehicle or the like and be mobile. Also, one NCR-MT 520A may control multiple NCR-Fwds 510A.

[0042] Note that the configuration is not limited to one in which the NCR-MT 520A directly controls one or more NCR-Fwds 510A, and may be one in which the NCR-MT 520A indirectly controls one or more NCR-Fwds 510A. For example, the NCR-MT 520A may control one or more NCR-Fwds 510A via a higher layer (for example, an application layer).

[0043] In the example shown in FIG. 5, the NCR device 500A (NCR-Fwd 510A) dynamically or quasi-statically changes the beam to be transmitted or received. For example, the NCR-Fwd 510A forms a beam toward each of the UE 100a and the UE 100b. The NCR-Fwd 510A may also form a beam toward the gNB 200. For example, in the communication resources between the gNB 200 and the UE 100a, the NCR-Fwd 510A transmits a radio signal received from the gNB 200 toward the UE 100a by beamforming, and / or transmits a radio signal received from the UE 100a toward the gNB 200 by beamforming. In the communication resources between the gNB 200 and the UE 100b, the NCR-Fwd 510A transmits a radio signal received from the gNB 200 toward the UE 100b by beamforming, and / or transmits a radio signal received from the UE 100b by beamforming toward the gNB 200. Instead of or in addition to beamforming, the NCR-Fwd 510A may form a null (so-called null steering) toward a UE 100 (not shown) and / or a neighboring gNB 200 (not shown) that is not a communication partner for interference suppression.

[0044] FIG. 6 is a diagram showing an example of a control method for the NCR device 500A according to the first embodiment.

[0045] The NCR-Fwd 510A relays radio signals (also referred to as "UE signals") between the gNB 200 and the UE 100. The UE signals include uplink signals (also referred to as "UE-UL signals") transmitted from the UE 100 to the gNB 200 and downlink signals (also referred to as "UE-DL signals") transmitted from the gNB 200 to the UE 100. The NCR-Fwd 510A relays UE-UL signals from the UE 100 to the gNB 200 and relays UE-DL signals from the gNB 200 to the UE 100. The radio link between the NCR-Fwd 510A and the UE 100 is also referred to as an "access link." The radio link between the NCR-Fwd 510A and the gNB 200 is also referred to as a "backhaul link."

[0046] The NCR-MT 520A transmits and receives radio signals (herein referred to as "NCR-MT signals") to and from the gNB 200. The NCR-MT signals include uplink signals (herein referred to as "NCR-MT-UL signals") transmitted from the NCR-MT 520A to the gNB 200, and downlink signals (herein referred to as "NCR-MT-DL signals") transmitted from the gNB 200 to the NCR-MT 520A. The NCR-MT-DL signals include signaling (e.g., NCR control signals) for controlling the NCR device 500A. The radio link between the NCR-MT 520A and the gNB 200 is also referred to as a "control link."

[0047] The gNB200 directs a beam to the NCR-MT520A based on the NCR-MT-UL signal from the NCR-MT520A. Because the NCR device 500A is co-located with the NCR-MT520A, if the backhaul link and the control link have the same frequency, when the gNB200 directs a beam to the NCR-MT520A, the beam will also be directed to the NCR-Fwd510A. The gNB200 uses this beam to transmit an NCR-MT-DL signal and a UE-DL signal. The NCR-MT520A receives the NCR-MT-DL signal. In addition, when the NCR-Fwd 510A and the NCR-MT 520A are at least partially integrated, the functions (e.g., antennas) for transmitting, receiving, or relaying UE signals and / or NCR-MT signals may be integrated in the NCR-Fwd 510A and the NCR-MT 520A. Note that the term "beam" includes a transmitting beam and / or a receiving beam. A beam is a general term for transmission and / or reception controlled to maximize the power of transmitted waves and / or received waves in a specific direction by adjusting / adapting antenna weights, etc.

[0048] FIG. 7 is a diagram for explaining an example of the configuration of a protocol stack in the NCR device 500A according to the first embodiment.

[0049] The NCR-Fwd 510A relays radio signals transmitted and received between the gNB 200 and the UE 100. The NCR-Fwd 510A has an RF (Radio Frequency) function that amplifies and relays received radio signals, and performs directional transmission using beamforming (e.g., analog beamforming).

[0050] The NCR-MT 520A has entities for each of the layers: Layer 1 and / or Layer 2 (L1 / L2), RRC, and NAS. The L1 / L2 (especially PHY and MAC) and RRC of the NCR-MT 520A are also referred to as the "AS of the NCR-MT 520A."

[0051] The NCR-MT 520A may have at least one of an OAM client that communicates with the OAM (Operation, Administration, Maintenance) server 400, a NAS layer that communicates with the AMF 300A, and an F1-AP (Application Protocol) layer. The OAM client, NAS layer, and F1-AP layer of the NCR-MT 520A are also referred to as the "upper layers of the NCR-MT 520A" based on the AS of the NCR-MT 520A.

[0052] A backhaul link is established between the gNB200 and the NCR-Fwd510A. An access link is established between the UE100 and the NCR-Fwd510A. The NCR-Fwd510A relays radio signals transmitted between the gNB200 and the UE100 via the backhaul link and the access link. The NCR-Fwd510A changes the propagation state of the radio signal without demodulating or modulating the radio signal.

[0053] In addition, a control link is established between gNB200 and L1 / L2 of NCR-MT520A. L1 / L2 of NCR-MT520A transmits and receives L1 / L2 signaling with gNB200 via the control link. An RRC connection is established between gNB200 and RRC of NCR-MT520A. RRC of NCR-MT520A transmits and receives RRC messages with gNB200 via the RRC connection. NCR-MT520A receives downlink signaling (also referred to as an "NCR control signal" or simply "control signal") from gNB200 via the RRC connection and / or the control link.

[0054] The gNB 200 (transmitter 210) transmits an NCR control signal to the NCR-MT 520A. The NCR control signal may be an RRC message, which is a control signal of the RRC layer (i.e., Layer 3). The NCR control signal may be a MAC Control Element (CE), which is a control signal of the MAC layer (i.e., Layer 2). The NCR control signal may be downlink control information (DCI), which is a control signal of the PHY layer (i.e., Layer 1). The NCR control signal may be UE-specific signaling. The NCR control signal may be broadcast signaling. The NCR control signal may be a fronthaul message (e.g., an F1-AP message). If the NCR-MT 520A is a type or part of a base station, the NCR-MT 520A may communicate with the gNB 200 via an Xn AP (Xn-AP), which is an inter-base station interface.

[0055] Hereinafter, an NCR control signal transmitted in an RRC message (and / or MAC CE) and used for static or semi-static control of the NCR-Fwd 510A will also be referred to as "NCR configuration information" or simply as "configuration information." Such configuration information may be referred to as "Side Control Configuration." Here, the RRC message may be an RRC Reconfiguration message. The NCR configuration information includes, for example, information for setting the NCR-Fwd 510A to on / off. The NCR configuration information may also include, for example, information for semi-static beam configuration of the NCR-Fwd 510A.

[0056] On the other hand, an NCR control signal transmitted in L1 / L2 signaling, i.e., DCI (and / or MAC CE), and used for dynamic control of the NCR-Fwd 510A is also referred to as "NCR control information" or simply "control information." The NCR control information may also be referred to as "Side Control Information." The CRC bits of the PDCCH carrying the NCR control information are scrambled by a newly introduced dedicated RNTI. This dedicated RNTI is also referred to as "NCR-RNTI." The NCR control information may include, for example, information 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.

[0057] For example, when the NCR-MT 520A is in the RRC connected state, the NCR device 500A can turn on or off the NCR-Fwd 510A according to the NCR control information received from the gNB 200. On the other hand, after the NCR-MT 520A transitions to the RRC inactive state, the NCR device 500A can turn on or off the NCR-Fwd 510A according to the latest (last) setting information received from the gNB 200.

[0058] In addition, the NCR control signal (e.g., NCR setting information by RRC and / or NCR control information by L1 / L2 signaling) held by the NCR device 500A (NCR-MT 520A) may be referred to as an NCR-Fwd context.

[0059] Also, if a radio link failure (RLF) with the gNB200 is detected by the NCR-MT520A, the NCR-MT520A performs cell selection and triggers RRC connection re-establishment (also referred to as "RRC re-establishment"). Here, if the NCR-MT520A enters an RRC idle state because a suitable cell cannot be found in the cell selection, the NCR device 500A turns off the NCR-Fwd510A. Note that the NCR-Fwd510A is off during the RRC connection re-establishment procedure.

[0060] The NCR control signal may include frequency control information that specifies the center frequency of the radio signal (e.g., component carrier) to be relayed by the NCR-Fwd 510A. When the NCR control signal received from the gNB 200 includes frequency control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to relay the radio signal having the center frequency indicated by the frequency control information (step S2A). The NCR control signal may include multiple pieces of frequency control information that specify different center frequencies. By including frequency control information in the NCR control signal, the gNB 200 can specify the center frequency of the radio signal to be relayed by the NCR-Fwd 510A via the NCR-MT 520A.

[0061] The NCR control signal may include mode control information that specifies the operation mode of the NCR-Fwd 510A. The mode control information may be associated with frequency control information (center frequency). The operation mode may be any of a mode in which the NCR-Fwd 510A performs omnidirectional transmission and / or reception, a mode in which the NCR-Fwd 510A performs fixed-directivity transmission and / or reception, a mode in which the NCR-Fwd 510A performs transmission and / or reception using a variable directional beam, and a mode in which the NCR-Fwd 510A performs MIMO (Multiple Input Multiple Output) relay transmission. The operation mode may be any of a beamforming mode (i.e., a mode that emphasizes improving the desired wave) and a null steering mode (i.e., a mode that emphasizes suppressing interference waves). When the NCR control signal received from the gNB 200 includes mode control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to operate in the operating mode indicated by the mode control information (step S2A). By including the mode control information in the NCR control signal, the gNB 200 can specify the operating mode of the NCR-Fwd 510A via the NCR-MT 520A.

[0062] Here, the mode in which the NCR device 500A performs omnidirectional transmission and / or reception is a mode in which the NCR-Fwd 510A performs omnidirectional relaying, and may be referred to as omni-mode. The mode in which the NCR-Fwd 510A performs fixed directional transmission and / or reception may be a directional mode realized by a single directional antenna. This mode may be a beamforming mode realized by applying fixed phase / amplitude control (antenna weight control) to multiple antennas. Any of these modes may be specified (set) by the gNB 200 to the NCR-MT 520A. The mode in which the NCR-Fwd 510A performs transmission and / or reception using a variable directional beam may be a mode in which analog beamforming is performed. This mode may be a mode in which digital beamforming is performed. This mode may be a mode in which hybrid beamforming is performed. This mode may be a mode in which an adaptive beam specific to the UE 100 is formed. Any of these modes may be specified (set) from the gNB 200 to the NCR-MT 520A. Note that in an operation mode in which beamforming is performed, beam control information, described below, may be provided from the gNB 200 to the NCR-MT 520A. The mode in which the NCR device 500A performs MIMO relay transmission may be a mode in which SU (Single-User) spatial multiplexing is performed. This mode may also be a mode in which MU (Multi-User) spatial multiplexing is performed. This mode may also be a mode in which transmit diversity is performed. Any of these modes may be specified (set) from the gNB 200 to the NCR-MT 520A. The operation modes may include a mode in which relay transmission by the NCR-Fwd 510A is turned on (activated) and a mode in which relay transmission by the NCR-Fwd 510A is turned off (deactivated). Any of these modes may be specified (set) by an NCR control signal from gNB200 to NCR-MT520A.

[0063] The NCR control signal may include beam control information that specifies the transmission direction, transmission weight, or beam pattern when the NCR-Fwd 510A performs directional transmission. The beam control information may be associated with frequency control information (center frequency). The beam control information may include a PMI (Precoding Matrix Indicator). The beam control information may include beam formation angle information. When the NCR control signal received from the gNB 200 includes beam control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to form the transmission directivity (beam) indicated by the beam control information. By including beam control information in the NCR control signal, the gNB 200 can control the transmission directivity of the NCR device 500A via the NCR-MT 520A.

[0064] The NCR control signal may include power control information that specifies the degree (gain) or transmission power by which the NCR-Fwd 510A amplifies the radio signal. The power control information may be information indicating a difference value (i.e., a relative value) between the current gain or transmission power and the target gain or transmission power. When the NCR control signal received from the gNB 200 includes power control information, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A to change the gain or transmission power to the gain or transmission power indicated by the transmission power control. The power control information may be associated with frequency control information (center frequency). The power control information may be information that specifies any of the amplifier gain, beamforming gain, and antenna gain of the NCR-Fwd 510A. The power control information may be information that specifies the transmission power of the NCR-Fwd 510A.

[0065] When one NCR-MT 520A controls multiple NCR-Fwds 510A, the gNB 200 (transmitter 210) may transmit an NCR control signal to the NCR-MT 520A for each NCR-Fwd 510A. In this case, the NCR control signal may include an identifier (NCR identifier) ​​of the corresponding NCR-Fwd 510A. The NCR-MT 520A (controller 523) that controls multiple NCR-Fwds 510A determines the NCR-Fwd 510A to which the NCR control signal is applied based on the NCR identifier included in the NCR control signal received from the gNB 200. Note that the NCR identifier may be transmitted from the NCR-MT 520A to the gNB 200 together with the NCR control signal, even when the NCR-MT 520A controls only one NCR-Fwd 510A.

[0066] In this way, the NCR-MT 520A (control unit 523) controls the NCR-Fwd 510A based on the NCR control signal from the gNB 200. This enables the gNB 200 to control the NCR-Fwd 510A via the NCR-MT 520A.

[0067] (1.3) Example of Configuration of Each Device Next, an example of the configuration of each device in the mobile communication system 1 according to the first embodiment will be described.

[0068] 8 is a diagram showing an example of the configuration of an NCR device 500A (relay device) according to the first embodiment. The NCR device 500A includes an NCR-Fwd 510A, an NCR-MT 520A, and an interface 530.

[0069] The NCR-Fwd 510A includes a radio unit 511A and an NCR control unit 512A. The radio unit 511A includes an antenna unit 511a including multiple antennas (multiple antenna elements), an RF circuit 511b including an amplifier, and a directivity control unit 511c that controls the directivity of the antenna unit 511a. The RF circuit 511b amplifies and relays (transmits) radio signals transmitted and received by the antenna unit 511a. The RF circuit 511b may convert analog radio signals into digital signals and then reconvert them to analog signals after digital signal processing. The directivity control unit 511c may perform analog beamforming using analog signal processing. The directivity control unit 511c may perform digital beamforming using digital signal processing. The directivity control unit 511c may perform hybrid analog and digital beamforming. The NCR control unit 512A controls the radio unit 511A in response to control signals from the NCR-MT 520A. The NCR control unit 512A may include at least one processor.

[0070] The NCR-MT 520A has a receiving unit 521, a transmitting unit 522, and a control unit 523. The receiving unit 521 performs various receptions under the control of the control unit 523. The receiving unit 521 includes an antenna and a receiver. The receiver converts a radio signal (wireless signal) received by the antenna into a baseband signal (received signal) and outputs it to the control unit 523. The transmitting unit 522 performs various transmissions under the control of the control unit 523. The transmitting unit 522 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmitted signal) output by the control unit 523 into a radio signal and transmits it from the antenna. The control unit 523 performs various controls on the NCR-MT 520A. The operations of the NCR-MT 520A (and the NCR device 500A) described above and below may be operations controlled by the control unit 523. The control unit 523 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes. In addition, the control unit 523 executes the functions of at least one layer of PHY, MAC, RRC, and F1-AP.

[0071] The interface 530 electrically or logically connects the NCR-Fwd 510A and the NCR-MT 520A. The control unit 523 of the NCR-MT 520A controls the NCR-Fwd 510A via the interface 530. The interface 530 may be a logical entity of an upper layer (e.g., an application layer).

[0072] In the first embodiment, the receiver 521 of the NCR-MT 520A receives signaling (NCR control signal) used to control the NCR device 500A from the gNB 200 via wireless communication. The controller 523 of the NCR-MT 520A controls the NCR device 500A based on the signaling. This enables the gNB 200 to control the NCR-Fwd 510A via the NCR-MT 520A.

[0073] (1.3.2) Example of configuration of user device Figure 9 is a diagram showing the configuration of the UE 100 (user device) according to the first embodiment. The UE 100 has a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit that performs wireless communication with the gNB 200.

[0074] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

[0075] The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0076] The control unit 130 performs various controls and processes in the UE 100. Such processes include processes of each layer described below. The operations of the UE 100 described above and below may be operations controlled by the control unit 130. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0077] (1.3.3) Example of network node configuration Figure 10 is a diagram showing an example of the configuration of a gNB 200 (network node) according to the first embodiment. The gNB 200 has a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240.

[0078] 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.

[0079] The control unit 230 performs various controls in the gNB 200. The operations of the gNB 200 described above and below may be operations controlled by the control unit 230. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0080] The backhaul communication unit 240 is connected to adjacent base stations via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF 300 via a base station-core network interface. The gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally divided), and the two units may be connected via an F1 interface.

[0081] In the first embodiment, the transmitter 210 of the gNB 200 transmits signaling (NCR control signal) used to control the NCR-Fwd 510A to the NCR-MT 520A via wireless communication. This enables the gNB 200 to control the NCR device 500A via the NCR-MT 520A.

[0082] (1.4) Operation of the Mobile Communication System Next, the operation of the mobile communication system 1 according to the first embodiment will be described.

[0083] (1.4.1) Example Operation Scenario FIG. 11 is a diagram for explaining an example operation scenario according to the first embodiment.

[0084] In the illustrated example, the NCR device 500A is installed at the edge of the cell of the gNB 200. The NCR device 500A is a RAN node having an NCR-Fwd 510A and an NCR-MT 520A. The NCR-Fwd 510A relays and transmits signals between the gNB 200 and the UE 100, specifically amplifying and forwarding UL / DL RF signals. The operation of the NCR-Fwd 510A is controlled according to side control information (control signal / NCR control signal) received by the NCR-MT 520A from the gNB 200. The NCR-MT 520A communicates with the gNB 200 via a control link to receive the side control information. The control link is based on the NR Uu interface.

[0085] The gNB 200 can form multiple beams using beamforming. The gNB 200 covers the coverage of its own cell with multiple beams. The gNB 200 may transmit different SSBs for each beam. Different SSBs may mean SSBs with different reference signal sequences. The gNB 200 may transmit different SSBs within its own cell while switching beams. The UE 100 that receives the SSB may perform physical random access channel (PRACH) transmission using random access resources associated with the received SSB (beam) during initial access. One of the beams of the gNB 200 may be directed toward the NCR device 500A. The gNB 200 may transmit different SSBs in a time-division manner using beams directed toward the NCR device 500A. The NCR device 500A (NCR-Fwd 510A) may relay the SSBs received from the gNB 200.

[0086] The NCR device 500A (NCR-Fwd 510A) can form multiple beams through beamforming. The NCR device 500A (NCR-Fwd 510A) can extend the coverage of the gNB200's cell by covering its own coverage with multiple beams. In other words, the coverage of the NCR device 500A (NCR-Fwd 510A) constitutes an extended area of ​​the gNB200's cell. The NCR device 500A (NCR-Fwd 510A) may be capable of forming beams of any width in any direction. As a basic setting, the NCR device 500A (NCR-Fwd 510A) may be capable of covering an area in all directions (360°) by transmitting beams of the same width at the same angular intervals. Hereinafter, a beam with such a setting will also be referred to as a "basic beam." The basic beam setting may be preset in the NCR device 500A. The setting may be set in the NCR device 500A by the gNB 200.

[0087] FIG. 12 is a diagram showing an example of a basic beam of the NCR device 500A according to the first embodiment. In the illustrated example, the NCR device 500A (NCR-Fwd 510A) forms four 90°-wide beams as basic beams. The NCR device 500A (NCR-Fwd 510A) may relay different SSBs for each beam. The gNB 200 may relay different SSBs while switching between beams. For example, the NCR device 500A (NCR-Fwd 510A) relays the following SSBs at different timings (slots): Beam #1: SSB #1 Beam #2: SSB #2 Beam #3: SSB #3 Beam #4: SSB #4.

[0088] The number indicated by "#" may represent an identifier (index).

[0089] In the example of Figure 12, there are zero UEs 100 accommodated by basic beam #1. There is one UE 100 (UE 100a) accommodated by basic beam #2. There are four UEs 100 (UE 100b to UE 100e) accommodated by basic beam #3. There is one UE 100 (UE 100f) accommodated by basic beam #4. In this example, the number of UEs 100 (traffic volume) accommodated by basic beam #3 is greater than that of other beams. Therefore, there may be a high probability of PRACH collision between UEs 100 accommodated by basic beam #3.

[0090] The gNB200 may perform statistical analysis of the UE distribution (traffic density) for each basic beam by communicating with the UE100 via the NCR device 500A, and determine the optimal beam direction and / or width of the NCR device 500A. The gNB200 transmits a request (setting) to apply the determined beam to the NCR device 500A (NCR-MT520A).

[0091] FIG. 13 is a diagram showing an example of an optimized beam of the NCR device 500A according to the first embodiment. In the illustrated example, the NCR device 500A (NCR-Fwd 510A) forms a new beam #5 with a width of 270° by combining the basic beam #1, basic beam #2, and basic beam #4. The NCR device 500A (NCR-Fwd 510A) also divides the basic beam #3 to form three new beams #6 to #8, each 30° wide. The NCR device 500A (NCR-Fwd 510A) may relay a different SSB for each new beam. The gNB 200 may relay different SSBs while switching between new beams. For example, the NCR device 500A (NCR-Fwd 510A) relays the following SSBs at different timings (slots): Beam #5: SSB #1 Beam #6: SSB #2 Beam #7: SSB #3 Beam #8: SSB #4.

[0092] In the example of Figure 13, there are two UEs 100 (UE 100a and UE 100f) served by new beam #5, zero UEs 100 (UE 100b) served by new beam #6, two UEs 100 (UE 100c and UE 100d) served by new beam #7, and one UE 100 (UE 100e) served by new beam #8.

[0093] As a result, even though the same four beams are used, the traffic for each beam is leveled, resource efficiency is increased, and system capacity is improved. In particular, the density (traffic density) of UEs 100 for each beam is leveled, and the PRACH collision probability is reduced. In addition, for physical downlink shared channel (PDSCH) transmission, the number of UEs in the same SSB direction is leveled, so the throughput for each UE 100 is likely to be fair.

[0094] In this way, in the first embodiment, under the control of the gNB 200, it is possible to flexibly change the state (beam characteristics) of the beam formed by the NCR device 500A (NCR-Fwd 510A), thereby improving resource efficiency (i.e., system capacity).

[0095] (1.4.2) Basic Operation FIG. 14 is a diagram showing the basic operation of the NCR device 500A according to the first embodiment.

[0096] In step S1, the NCR device 500A (NCR-MT 520A) may transmit capability information (also referred to as "beam capability information") indicating the capability of the NCR device 500A (NCR-Fwd 510A) regarding beam combining (also referred to as "aggregation") and / or beam splitting (also referred to as "separation") to the gNB 200 over the control link. The NCR device 500A (NCR-MT 520A) may include the beam capability information in a UE Capability Information message, which is a type of RRC message, and transmit the UE Capability Information message including the beam capability information to the gNB 200. The NCR device 500A (NCR-MT520A) may send a UE Capability Information message to the gNB200 in response to receiving a UE Capability Enquiry message, which is a type of RRC message, from the gNB200.

[0097] The beam capability information may include at least one of the following information: - Information indicating the combination of basic beams required to cover the coverage area of ​​the NCR device 500A; - Information indicating the number of divisions possible for each of the multiple basic beams; - For each of the multiple basic beams, beam identifiers of preset divided beams; - For each of the multiple basic beams, beam identifiers of other basic beams that can be combined with the basic beam.

[0098] In addition, the NCR device 500A (NCR-MT 520A) does not need to transmit its own beam capability information to the gNB 200. The gNB 200 may obtain the beam capability information of the NCR device 500A (NCR-Fwd 510A) from the OAM (for example, the OAM server 400).

[0099] In step S2, the NCR device 500A (NCR-MT 520A) forms multiple basic beams in different directions. Each of the multiple basic beams is assigned a beam identifier. The NCR device 500A (NCR-Fwd 510A) may cover an area in all directions (360°) by transmitting the basic beams at the same angular intervals. Alternatively, the NCR device 500A (NCR-Fwd 510A) may cover an area of ​​a partial range (e.g., 180°) rather than an area in all directions (360°) by transmitting the basic beams at the same angular intervals. Note that the order of steps S1 and S2 may be reversed.

[0100] In step S3, the NCR device 500A (NCR-MT 520A) receives a beam change request from the gNB 200 over the control link, the beam change request specifying two or more basic beams to be combined among the multiple basic beams and / or a basic beam to be split among the multiple basic beams. The beam change request includes each beam identifier of the two or more basic beams to be combined and / or the beam identifier of the basic beam to be split. The NCR device 500A (NCR-MT 520A) may receive an RRC message (e.g., an RRC Reconfiguration message) including the beam change request, a MAC CE including the beam change request, or a DCI including the beam change request from the gNB 200.

[0101] In step S4, in response to receiving the beam change request in step S3, the NCR device 500A (NCR-Fwd 510A) combines and / or splits the basic beams specified in the beam change request.

[0102] In step S5, the NCR device 500A (NCR-MT 520A) may assign a new beam identifier to each new beam obtained by combining the basic beams and / or by splitting the basic beams.

[0103] In step S6, the NCR device 500A (NCR-MT 520A) transmits a notification ("beam change notification") including the new beam identifier assigned in step S5 to the gNB 200. The NCR device 500A (NCR-MT 520A) may transmit an RRC message (e.g., an RRC Reconfiguration Complete message or a UE Assistance Information message) including the beam change notification, a MAC CE including the beam change notification, or uplink control information (UCI) including the beam change notification to the gNB 200.

[0104] The beam change notification may include at least one of the following information: - Information indicating the correspondence between each beam identifier of two or more combined basic beams and the beam identifier of the new beam obtained by the combination; - Information indicating the correspondence between the beam identifier of the divided basic beams and the beam identifier of each new beam obtained by the division.

[0105] The NCR device 500A may repeatedly execute the operation flow shown in Fig. 14. For example, the NCR device 500A may execute the (n+1)th operation flow using the beam obtained by aggregation and / or separation in the nth operation flow as a new basic beam.

[0106] The NCR device 500A that operates as shown in Figure 14 includes an NCR-Fwd 510A that forms multiple basic beams in different directions, and an NCR-MT 520A that receives a beam change request from the gNB 200 specifying two or more basic beams to be combined from the multiple basic beams and / or a basic beam to be split from the multiple basic beams. In response to receiving the beam change request, the NCR-Fwd 510A combines and / or splits the basic beams specified in the beam change request. Meanwhile, the gNB 200 includes a transmitter 210 that transmits a beam change request to the NCR-MT 520A that specifies two or more basic beams to be combined from the multiple basic beams formed by the NCR-Fwd 510A in different directions and / or a basic beam to be split from the multiple basic beams.

[0107] (1.4.3) Specific Examples of Operation As specific examples of the operation of the mobile communication system 1 according to the first embodiment, a first operation pattern and a second operation pattern will be described. Each of these operation patterns may be implemented independently. Two or more of these operation patterns may be implemented in combination.

[0108] (1.4.3.1) First Operation Pattern Figure 15 is a diagram showing the first operation pattern of the mobile communication system 1 according to the first embodiment. In the first operation pattern, the gNB 200 instructs the NCR device 500A (NCR-MT 520A) to aggregate and / or separate beams. The NCR device 500A (NCR-MT 520A) assigns a new beam identifier to the aggregated / separated beam and notifies the gNB 200. The beam identifier is an identifier for identifying each beam. The beam identifier may be a beam index or TCI state ID used in Side Control Information (MAC CE).

[0109] In step S101, the NCR device 500A (NCR-MT520A) is in an RRC connected state in the cell of the gNB200.

[0110] In step S102, the gNB200 acquires information on the basic beam characteristics of the NCR device 500A (NCR-Fwd510A) from the OAM. For example, the gNB200 may acquire information from the OAM indicating a setting (basic beam #1, basic beam #2, basic beam #3, basic beam #4) that covers 360° with four beams. Note that these four beams may be 90° wide or may have non-uniform beam widths. The gNB200 does not need to know the details of each basic beam. For example, the gNB200 does not need to know detailed information such as which basic beam (beam ID) has which direction and how many degrees of width.

[0111] In step S103, gNB200 may assign different SSBs to each of the multiple base beams of NCR device 500A (NCR-Fwd510A). For example, gNB200 assigns {Base beam #1, SSB #1}, {Base beam #2, SSB #2}, {Base beam #3, SSB #3}, and {Base beam #4, SSB #4}. gNB200 may transmit information (setting information) indicating the assignment to NCR device 500A (NCR-MT520A).

[0112] In step S104, gNB200 determines the aggregation and / or separation of the basic beams of NCR device 500A (NCR-Fwd 510A). For example, gNB200 may determine to optimize the basic beams based on the number and / or traffic volume of UEs 100 with which it communicates via NCR device 500A (NCR-Fwd 510A). For example, gNB200 determines that the traffic volume of beam #1, beam #2, and beam #3 is low, and the traffic volume of beam #4 is high (i.e., congested). In this case, gNB200 determines the aggregation of beam #1, beam #2, and beam #3, and determines the separation of beam #4.

[0113] In step S105, gNB200 transmits a beam change request (beam adjustment request) to NCR device 500A (NCR-MT520A). NCR device 500A (NCR-MT520A) receives the beam change request. The beam change request includes at least one of the following information 1) and 2).

[0114] 1) Information indicating a set of beam identifiers of the basic beams to be aggregated: For example, the information includes the beam identifiers (#1, #2, #3) of each of the basic beams to be aggregated, such as basic beam #1, basic beam #2, and basic beam #3.

[0115] 2) Information indicating the beam identifier and number of divisions of the basic beam to be separated: For example, this information includes information such as the beam identifier (#4) of this basic beam and the number of divisions "3" in order to divide basic beam #4 into three.

[0116] In step S106, the NCR device 500A (NCR-MT 520A) performs aggregation and / or separation of the basic beams specified in the beam change request in step S105.

[0117] For example, if the NCR device 500A (NCR-MT520A) accepts a beam change request specifying an aggregation of basic beam #1, basic beam #2, and basic beam #3, it calculates beam characteristics that can cover these three beams with a single new beam and assigns a new beam identifier (e.g., beam #5) to the beam characteristics. The beam width of the new beam must be equal to or greater than the sum of the original three beam widths (e.g., 90° x 3 = 270°). However, the NCR device 500A (NCR-MT520A) may determine that the request is not acceptable. For example, if the three beams specified for aggregation are not adjacent and therefore cannot be aggregated, the NCR device 500A (NCR-MT520A) determines that the request is not acceptable.

[0118] For example, if a beam change request specifies that basic beam #4 be divided into three, and the NCR device 500A (NCR-MT520A) accepts the request, it calculates beam characteristics that allow basic beam #4 to be covered by three beams and assigns beam identifiers of new beams (e.g., beam #6, beam #7, and beam #8) to the beam characteristics. Each of the new beams may have a beam width that is an equal division of the original beam width (e.g., 90° ÷ 3 = 30°), or may have a non-uniform beam width. However, the NCR device 500A (NCR-MT520A) may determine that the request is not acceptable. For example, if the NCR device 500A (NCR-MT520A) does not have the ability to generate a beam narrower than 90° wide, it determines that the request is not acceptable.

[0119] In step S107, the NCR device 500A (NCR-MT 520A) transmits a notification (beam change notification) indicating the results of the aggregation and / or separation in step S106 to the gNB 200 over the control link. The gNB 200 receives the beam change notification. Here, the NCR device 500A (NCR-MT 520A) notifies the gNB 200 of the newly assigned beam identifier in step S106.

[0120] The beam change notification may include information linking the new beam identifier with the original beam identifier. For example, the information may include aggregation information indicating that the aggregation of {Beam #1, Beam #2, Beam #3} is Beam #5. The information may include separation information indicating that the separation of Beam #4 is {Beam #6, Beam #7, Beam #8}.

[0121] The notification of step S107 may include information indicating that the request of step S105 was not accepted, such as information indicating that aggregation of {beam #1, beam #2, beam #3} is not possible and / or separation of beam #4 is not possible.

[0122] In step S108, gNB200 may allocate SSBs to the new beam identifiers notified in step S107. For example, gNB200 may allocate {beam #5, SSB #1}, {beam #6, SSB #2}, {beam #7, SSB #3}, and {beam #8, SSB #4}. gNB200 may transmit information indicating the allocation to NCR device 500A (NCR-MT520A). However, NCR device 500A (NCR-Fwd510A) performs PDSCH relay and PUSCH relay in addition to SSB relay, so it is not limited to the operation of allocating SSBs. In addition, gNB200 may transmit information indicating the setting of a non-periodic beam (periodic beam indication) to NCR device 500A (NCR-MT520A). The information (periodic beam indication) may include a beam identifier of the beam selected by gNB200 from the basic beam and the new beam.

[0123] Such an operation allows the NCR device 500A (NCR-Fwd 510A) to operate with an optimized beam, thereby improving the system capacity.

[0124] (1.4.3.2) Second Operation Pattern Figure 16 is a diagram showing the second operation pattern of the mobile communication system 1 according to the first embodiment. In the second operation pattern, the NCR device 500A (NCR-MT 520A) notifies the gNB 200 of the beam aggregation / separation capability information (beam capability information) of the NCR-Fwd 510A. This allows the gNB 200 to understand the beam characteristics of the NCR-Fwd 510A based on the beam capability information without relying on OAM.

[0125] In step S201, the NCR device 500A (NCR-MT520A) is in an RRC connected state in the cell of the gNB200.

[0126] In step S202, the NCR device 500A (NCR-MT 520A) transmits beam aggregation / separation capability information (beam capability information) of the NCR-Fwd 510A to the gNB 200. The gNB 200 receives the beam capability information.

[0127] The beam capability information includes at least one of the following information 1) to 4).

[0128] 1) Information indicating basic beams required to cover the coverage area of ​​the NCR device 500A: This information may include information indicating basic beams for covering 360° (e.g., beams #1 to #4 can be used to cover 360°). Alternatively, it may be information indicating basic beams for covering the maximum area width, even if not 360°.

[0129] 2) Information indicating the number of divisions of each basic beam: This information may be information indicating the maximum number of divisions of each basic beam. Specifically, it may be the number of divisions that can be dynamically divided (separated) in the first operation pattern.

[0130] 3) Beam identifiers of preset divided beams of each basic beam: For example, this information may be information indicating that three divided beams (beam #6, beam #7, beam #8) are preset for basic beam #1. In this case, it indicates that beam #1 has been divided into three in advance. This does not assume dynamic aggregation / separation as in the first operation pattern, but indicates the linkage between beams (hierarchical structure).

[0131] 4) For each basic beam, beam identifiers of other basic beams that can be aggregated with the basic beam: For example, this information may be information such as that basic beam #1 can be aggregated with other basic beams {beam #2, beam #3, beam #4}. In this case, it indicates that beam #1 and beam #2 can be aggregated, beam #1 and beam #3 can be aggregated, and beam #1 and beam #4 can be aggregated.

[0132] For example, the beam capability information regarding basic beam #1 may have the following data structure: Basic beam flag = True Preset divided beams {beam #6, beam #7, beam #8} Number of possible divisions = 8 Other basic beams that can be aggregated {beam #2, beam #3, beam #4} Similar data structures may also be used for other basic beams.

[0133] In step S203, gNB200 may allocate an SSB to each beam (each basic beam) indicated in the beam capability information of step S202. As with the first operation pattern, gNB200 may request aggregation / separation of a certain beam from NCR device 500A (NCR-MT520A). gNB200 may transmit information indicating the setting of an aperiodic beam (aperiodic beam indication) to NCR device 500A (NCR-MT520A). The information (aperiodic beam indication) may include a beam identifier of a beam selected by gNB200 from among the basic beams and the new beam.

[0134] (2) Second Embodiment Next, a second embodiment will be described, focusing on differences from the above-described embodiments. As shown in Fig. 17, the relay device according to the second embodiment is a Reconfigurable Intelligent Surface (RIS) device 500B that performs relay transmission by changing the propagation direction of incident radio waves (wireless signals) through reflection or refraction. The term "NCR" in the above-described embodiments can be read as "RIS."

[0135] RIS is a type of repeater (hereinafter also referred to as "RIS-Fwd") that can perform beamforming (directivity control) similar to NCR by changing the properties of a metamaterial. In the case of RIS, the range (distance) of the beam may also be changed by controlling the reflection direction and / or refraction direction of each unit element. For example, the RIS may be configured to control the reflection direction and / or refraction direction of each unit element and to focus (direct the beam) on a nearby UE or a distant UE.

[0136] The RIS device 500B has a new UE (hereinafter referred to as "RIS-MT") 520B, which is a control terminal for controlling the RIS-Fwd 510B. The RIS-MT 520B establishes a wireless connection with the gNB 200 and performs wireless communication with the gNB 200, thereby controlling the RIS-Fwd 510B in cooperation with the gNB 200. The RIS-Fwd 510B may be a reflective RIS. Such a RIS-Fwd 510B changes the propagation direction of incident radio waves by reflecting the radio waves. Here, the reflection angle of the radio waves is variably settable. The RIS-Fwd 510B reflects radio waves incident from the gNB 200 toward the UE 100. The RIS-Fwd 510B may be a transparent RIS. Such a RIS-Fwd 510B changes the propagation direction of the radio waves by refracting the incident radio waves. Here, the refraction angle of the radio wave can be variably set.

[0137] FIG. 18 is a diagram showing an example configuration of a RIS-Fwd (repeater) 510B and a RIS-MT (control terminal) 520B according to the second embodiment. The RIS-MT 520B includes a receiver 521, a transmitter 522, and a controller 523. This configuration is similar to that of the above-described embodiment. The RIS-Fwd 510B includes a RIS 511B and a RIS controller 512B. The RIS 511B is a metasurface constructed using a metamaterial. For example, the RIS 511B is constructed by arranging structures that are very small relative to the wavelength of radio waves in an array. By making the structures different shapes depending on their placement, it is possible to arbitrarily design the direction and / or beam shape of the reflected waves. The RIS 511B may also be a transparent dynamic metasurface. The RIS 511B may be configured by overlaying a transparent glass substrate on a transparent metasurface substrate on which a large number of small structures are regularly arranged, and by slightly moving the overlaid glass substrate, it may be possible to dynamically control three patterns: a mode that transmits incident radio waves, a mode that transmits some of the radio waves and reflects some of them, and a mode that reflects all of the radio waves. The RIS control unit 512B controls the RIS 511B in response to a RIS control signal from the control unit 523 of the RIS-MT 520B. The RIS control unit 512B may include at least one processor and at least one actuator. The processor decodes the RIS control signal from the control unit 523 of the RIS-MT 520B and drives the actuator in response to the RIS control signal.

[0138] (3) Other Embodiments In the above-described embodiment, an example has been described in which the relay device that performs relay transmission is the NCR device 500A or the RIS device 500B. However, the relay device that performs relay transmission is not limited to the NCR device 500A or the RIS device 500B, and may be an IAB (Integrated Access and Backhaul) node defined in the 3GPP technical specifications.

[0139] The above-described operational flows are not limited to being implemented independently, but can also be implemented by combining two or more operational flows. For example, some steps of one operational flow may be added to another operational flow, or some steps of one operational flow may be replaced with some steps of another operational flow. In each flow, it is not necessary to execute all steps, and only some steps may be executed.

[0140] In the above embodiment, an example in which the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB). The base station may also be a relay node such as an IAB node. The base station may also be a Distributed Unit (DU) of the IAB node. The UE 100 may also be a Mobile Termination (MT) of the IAB node.

[0141] That is, the UE 100 may be a terminal function unit (a type of communication module) for a base station to control a repeater that relays signals. Such a terminal function unit is referred to as an MT. Examples of the MT include, in addition to the IAB-MT, an NCR (Network Controlled Repeater)-MT and a RIS (Reconfigurable Intelligent Surface)-MT.

[0142] The term "network node" primarily refers to a base station, but may also refer to a core network device or a part of a base station (CU, DU, or RU). A network node may also be configured by a combination of at least a part of a core network device and at least a part of a base station.

[0143] 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 a computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by the UE100 or the gNB200 may be integrated, and at least a portion of the UE100 or the gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0144] The functions performed by the UE 100 or the gNB 200 (network node) 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 perform the described functions. A processor includes transistors and other circuits and is considered to be circuitry or processing circuitry. A processor may also be a programmed processor that executes a program stored in memory. In this specification, circuitry, unit, or means refers to hardware that is programmed to perform the described functions or hardware that executes them. The hardware may be any hardware disclosed herein or any hardware known to be programmed or capable of performing the described functions. If the hardware is a processor, the circuitry, means, or unit is a combination of hardware and software used to configure the hardware and / or processor.

[0145] As used in this disclosure, the terms "based on" and "depending on / in response to" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "depending only on" and "depending at least in part on." The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Additionally, the term "or," as used in this disclosure, is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0146] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention.

[0147] This application claims priority from Japanese Patent Application No. 2023-141204 (filed August 31, 2023), the entire contents of which are incorporated herein by reference.

[0148] (4) Supplementary Notes The following are additional notes regarding the features of the above-described embodiment.

[0149] (Supplementary Note 1) A communication method using a relay device having a relay device that relays and transmits radio signals between a network node and a user device, and a control terminal used to control the relay device, comprising: a step in which the relay device forms a plurality of basic beams in different directions; a step in which the control terminal receives from the network node a beam change request that specifies two or more basic beams to be combined from the plurality of basic beams and / or a basic beam to be split from the plurality of basic beams; and a step in which, in response to receiving the beam change request, the relay combines and / or splits the basic beams specified in the beam change request.

[0150] (Supplementary Note 2) A communication method as described in Supplementary Note 1, in which each of the plurality of basic beams is assigned a beam identifier for identifying the basic beam, and the beam change request includes each beam identifier of the two or more basic beams to be combined and / or the beam identifier of the basic beam to be split.

[0151] (Supplementary Note 3) The communication method described in Supplementary Note 2 further comprises the steps of: the relay device assigning a new beam identifier to each new beam obtained by the combination and / or each new beam obtained by the division; and the control terminal transmitting a notification including the new beam identifier to the network node.

[0152] (Supplementary Note 4) The communication method described in Supplementary Note 3, wherein the notification includes information indicating the correspondence between each beam identifier of the two or more combined basic beams and the beam identifier of the new beam obtained by the combination.

[0153] (Supplementary Note 5) The communication method according to Supplementary Note 3 or 4, wherein the notification includes information indicating a correspondence between the beam identifier of the divided basic beam and the beam identifier of each new beam obtained by the division.

[0154] (Supplementary Note 6) The communication method according to any one of Supplementary Notes 1 to 5, further comprising the step of transmitting capability information indicating a capability of the relay device regarding the combining and / or the splitting from the control terminal to the network node.

[0155] (Supplementary Note 7) The communication method according to Supplementary Note 6, wherein the capability information includes information indicating a combination of basic beams required to cover the coverage area of ​​the relay device.

[0156] (Supplementary Note 8) The communication method according to Supplementary Note 6 or 7, wherein the capability information includes information indicating the number of divisions that each of the plurality of base beams can have.

[0157] (Supplementary Note 9) The communication method according to any one of Supplementary Notes 6 to 8, wherein the capability information includes beam identifiers of preset divided beams for each of the plurality of basic beams.

[0158] (Supplementary Note 10) The communication method according to any one of Supplementary Notes 6 to 9, wherein the capability information includes, for each of the plurality of basic beams, beam identifiers of other basic beams that can be combined with the basic beam.

[0159] (Supplementary Note 11) A relay device comprising: a repeater that relays and transmits radio signals between a network node and a user device; and a control terminal used to control the repeater, wherein the repeater forms a plurality of basic beams in different directions, the control terminal receives a beam change request from the network node that specifies two or more basic beams to be combined from the plurality of basic beams and / or a basic beam to be split from the plurality of basic beams, and the repeater combines and / or splits the basic beams specified in the beam change request in response to receiving the beam change request.

[0160] (Supplementary Note 12) A network node that communicates with a relay device having a relay device that performs relay transmission to relay radio signals transmitted between the network node and a user device, and a control terminal used to control the relay device, the network node comprising: a transmitter that transmits to the control terminal a beam change request that specifies two or more basic beams to be combined from among a plurality of basic beams formed by the relay device in different directions and / or a basic beam to be split from among the plurality of basic beams.

[0161] 1: Mobile communication system 100: UE 200: gNB 210: Transmitter 220: Receiver 230: Controller 240: Backhaul communication unit 300A: AMF 400: OAM server 500A: NCR device 510A: NCR-Fwd 520A: NCR-MT 500B: RIS device 510B: RIS-Fwd 520B: RIS-MT 511A: Wireless unit 511a: Antenna unit 511b: RF circuit 511c: Directivity control unit 512A: NCR control unit 512B: RIS control unit 521: Receiver 522: Transmitter 523: Controller 530: Interface 550: Sensor

Claims

1. A communications method using a relay device having a repeater that relays radio signals between a network node and a user device, and a control terminal used to control the repeater, comprising: the repeater forming a plurality of basic beams each in a different direction; the control terminal receiving from the network node a beam change request specifying two or more basic beams to be combined from the plurality of basic beams and / or a basic beam to be split from the plurality of basic beams; and in response to receiving the beam change request, the repeater combining and / or splitting the basic beams specified in the beam change request.

2. The communication method described in claim 1, wherein each of the multiple basic beams is assigned a beam identifier for identifying that basic beam, and the beam change request includes each beam identifier of the two or more basic beams to be combined and / or a beam identifier of the basic beam to be split.

3. The communication method described in claim 2, further comprising: the relay device assigning a new beam identifier to each new beam obtained by the combination and / or each new beam obtained by the division; and transmitting a notification including the new beam identifier from the control terminal to the network node.

4. The communication method described in claim 3, wherein the notification includes information indicating a correspondence between each beam identifier of the two or more combined basic beams and the beam identifier of a new beam obtained by the combination.

5. A communication method as described in claim 3 or 4, wherein the notification includes information indicating the correspondence between the beam identifier of the divided basic beam and the beam identifier of each new beam obtained by the division.

6. The communication method according to claim 1, further comprising transmitting capability information indicating a capability of said relay device with respect to said combining and / or said splitting from said control terminal to said network node.

7. The communication method according to claim 6, wherein the capability information includes information indicating a combination of basic beams required to cover the coverage area of ​​the relay device.

8. The communication method according to claim 6, wherein the capability information includes information indicating the number of divisions that each of the plurality of basic beams can be divided into.

9. The communication method according to claim 6, wherein the capability information includes beam identifiers of preset divided beams for each of the plurality of basic beams.

10. The communication method according to claim 6, wherein the capability information includes, for each of the plurality of basic beams, beam identifiers of other basic beams that can be combined with the basic beam.

11. A relay device comprising: a repeater that relays and transmits radio signals between a network node and a user equipment; and a control terminal used to control the repeater, wherein the repeater forms a plurality of basic beams each in a different direction; the control terminal receives a beam changing request from the network node, the beam changing request specifying two or more basic beams to be combined from the plurality of basic beams and / or a basic beam to be split from the plurality of basic beams; and the repeater, in response to receiving the beam changing request, combines and / or splits the basic beams specified in the beam changing request.

12. A network node that communicates with a relay device having a repeater that performs relay transmission to relay radio signals transmitted between the network node and a user device, and a control terminal used to control the repeater, the network node having a transmitter that transmits to the control terminal a beam change request that specifies two or more basic beams to be combined from among a plurality of basic beams formed by the repeater in different directions and / or a basic beam to be split from among the plurality of basic beams.

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