Communication methods, repeater nodes, programs, chipsets, systems, and user equipment

Abstract

This invention provides communication methods, repeater nodes, programs, chipsets, systems, and user equipment for use in mobile communication systems. [Solution] A communication method using a relay device having a relay device that performs a relay operation to relay wireless signals transmitted between a network and a user device, and a control terminal that receives control signals from the network to be used to control the relay device, the method comprising the steps of: when the control terminal is in a radio resource control (RRC) idle state or RRC inactive state in a first cell and the relay device is on, the control terminal starts a procedure for a second cell to transition to an RRC connected state; and the relay device turns off the relay device based on the start of the procedure.

Description

Technical Field

[0001] The present disclosure relates to a communication method, a repeater node, a program, a chipset, a system, and a user device used in a mobile communication system.

Background Art

[0002] In recent years, the fifth-generation (5G) mobile communication system has attracted attention. NR (New Radio), which is a radio access technology of the 5G system, enables broadband transmission in a high-frequency band compared to LTE (Long Term Evolution), which is a fourth-generation radio access technology.

[0003] Since radio signals (radio waves) in high-frequency bands such as the millimeter-wave band or the terahertz wave band have high directivity, reducing the coverage of the base station becomes an issue. To solve such an issue, a repeater device that relays radio signals between a network and a user device has attracted attention (see, for example, Non-Patent Document 1). Such a repeater device can expand the coverage of the base station while suppressing the occurrence of interference by, for example, amplifying radio signals received from the base station and transmitting them by directional transmission. Note that such a repeater device is also referred to as an NCR (Network-controlled Repeater).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

[0005] A communication method according to the first embodiment is a communication method using a relay device having a relay device that performs a relay operation to relay wireless signals transmitted between a network and a user device, and a control terminal that receives control signals from the network used to control the relay device, wherein when the control terminal transitions from a wireless resource control (RRC) connected state to an RRC inactive state, the relay device is instructed to continue the relay operation; when the control terminal is in an RRC inactive state, the control terminal initiates a procedure to restore to an RRC connected state; the control terminal receives a message from the network to turn off the relay device based on the initiation of the procedure; and when the relay device receives the message, it instructs the relay device to stop the relay operation.

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

[0007] The relay device according to the third embodiment comprises a relay unit that performs a relay operation to relay wireless signals transmitted between a network and a user device, and a control terminal that receives control signals from the network used to control the relay unit, wherein the control terminal initiates a procedure for the second cell to transition to the RRC connected state when the first cell is in a wireless resource control (RRC) idle state or RRC inactive state and the relay unit is turned on, and turns off the relay unit based on the initiation of the procedure. [Brief explanation of the drawing]

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

Modes for Carrying Out the Invention

[0009] A mobile communication system according to an embodiment will be described while referring to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

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

[0011] (1.1) Overview of Mobile Communication System FIG. 1 is a diagram showing the configuration of a mobile communication system according to the embodiment.

[0012] The mobile communication system 1 complies with the 5th generation system (5GS: 5th Generation System) of the 3rd Generation Partnership Project (3GPP) (registered trademark; the same applies hereinafter). Hereinafter, the 5GS will be described as an example, but the LTE (Long Term Evolution) system may be at least partially applied to the mobile communication system. The 6th generation (6G) system may be at least partially applied to the mobile communication system.

[0013] The mobile communication system 1 comprises User Equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20. Hereinafter, NG-RAN 10 may be simply referred to as RAN 10, and 5GC 20 may be simply referred to as the core network (CN) 20. RAN 10 and CN 20 constitute the network 5 of the mobile communication system 1.

[0014] UE100 is a mobile wireless communication device. UE100 can be any device used by a user. For example, UE100 can be a mobile phone terminal (including smartphones) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or chipset), a sensor or device attached to a sensor, a vehicle or device attached to a vehicle (Vehicle UE), or an aircraft or device attached to an aircraft (Aerial UE).

[0015] NG-RAN10 includes base stations (referred to as "gNBs" in 5G systems) 200. The gNBs 200 are interconnected via the Xn interface, which is an inter-base station interface. Each gNB 200 manages one or more cells. The gNB 200 performs wireless communication with UEs 100 that have established a connection with its own cell. The gNB 200 has radio resource management (RRM) functions, user data routing functions (hereinafter simply referred to as "data"), measurement and control functions for mobility control and scheduling, etc. "Cell" is used as a term to indicate the smallest unit of a wireless communication area. "Cell" is also used as a term to indicate a function or resource that performs wireless communication with the UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0016] 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 the upper layers of the protocol stack described later, such as the RRC layer, SDAP layer, and PDCP layer. The CU is connected to the core network via the NG interface, which is the backhaul interface. The CU is connected to neighboring base stations via the Xn interface, which is the inter-base station interface. The DU forms a cell. The DU202 is a unit that includes the lower layers of the protocol stack described later, such as the RLC layer, MAC layer, and PHY layer. The DU is connected to the CU via the F1 interface, which is the fronthaul interface.

[0017] Furthermore, gNBs can also connect to the EPC (Evolved Packet Core), which is the core network of LTE. LTE base stations can also connect to 5GCs. LTE base stations and gNBs can also be connected via an inter-base station interface.

[0018] The 5GC20 includes the AMF (Access and Mobility Management Function) and the UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE100. The AMF manages the mobility of the UE100 by communicating with it using NAS (Non-Access Stratum) signaling. The UPF controls data transfer. The AMF and UPF are connected to the gNB200 via the NG interface, which is the base station-core network interface.

[0019] Figure 2 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0020] The user plane radio interface protocol consists of a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an SDAP (Service Data Adaptation Protocol) layer.

[0021] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the UE100's PHY layer and the gNB200's PHY layer via a physical channel. The UE100's PHY layer receives downlink control information (DCI) transmitted from the gNB200 over the physical downlink control channel (PDCCH). Specifically, the UE100 performs blind decoding of the PDCCH using a Radio Network Temporary Identifier (RNTI) and acquires the successfully decoded DCI as the DCI addressed to its own UE. The DCI transmitted from the gNB200 has CRC bits added to it that have been scrambled by the RNTI.

[0022] The gNB200 also transmits Synchronization Signal (SSB) blocks (PBCH blocks). For example, an SSB consists of four consecutive OFDM (Orthogonal Frequency Division Multiplex) symbols, containing 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 an SSB is, for example, 240 consecutive subcarriers, i.e., a bandwidth of 20 RB.

[0023] 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 the UE100 and the MAC layer of the gNB200 via the transport channel. The MAC layer of the gNB200 includes a scheduler. The scheduler determines the transport format for the up and down links (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE100.

[0024] 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 UE100's RLC layer and the gNB200's RLC layer via a logical channel.

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

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

[0027] Figure 3 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0028] The control plane's wireless interface protocol stack includes an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer, instead of the SDAP layer shown in Figure 2.

[0029] RRC signaling for various settings is transmitted between the RRC layer of the UE100 and the RRC layer of the gNB200. The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. If there is a connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC connected state. If there is no connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC idle state. If the connection between the RRC of the UE100 and the RRC of the gNB200 is suspended, the UE100 is in the RRC inactive state.

[0030] The NAS layer, located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the UE100's NAS layer and the AMF300A's NAS layer. The UE100 also has application layers and other components in addition to its wireless interface protocol. Furthermore, layers below the NAS layer are referred to as the AS layer.

[0031] (1.2) Examples of application scenarios for relay devices Figures 4 and 5 show an example of an application scenario for the NCR device according to the embodiment.

[0032] 5G / NR enables broadband transmission using high frequency bands compared to 4G / LTE. However, since radio signals in high frequency bands such as millimeter waves or terahertz waves have high directivity, reducing the coverage of gNB200 becomes a challenge. In Figure 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 also be obstacles between gNB200 and UE100, preventing UE100 from communicating with gNB200 within line of sight.

[0033] As shown in Figure 4, a repeater device (500A), which is a type of relay device that relays wireless signals between gNB200 and UE100, is introduced into the mobile communication system 1 as an NCR device 500A that can be controlled from the network. Such a repeater device may also be called a smart repeater device.

[0034] For example, the NCR device 500A amplifies the radio signal (radio wave) received from the gNB200 and transmits it via directional transmission. Specifically, the NCR device 500A receives the radio signal transmitted by the gNB200 via beamforming. The NCR device 500A then amplifies the received radio signal without demodulation or modulation, and transmits the amplified radio signal via directional transmission. Here, the NCR device 500A may transmit the radio signal with a fixed directionality (beam). The NCR device 500A may transmit the radio signal with a variable (adaptive) directional beam. This allows for efficient expansion of the gNB200's coverage.

[0035] Furthermore, as shown in Figure 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, will be introduced. Specifically, the NCR device 500A includes an NCR-Fwd (Forward) 510A, which is a type of repeater that relays the radio signal transmitted between the gNB200 and the UE100, and changes the propagation state of the radio signal without demodulating or modulating the radio signal, and an NCR-MT 520A, which controls the NCR-Fwd 510A by performing wireless communication with the gNB200. In this way, the NCR-MT 520A controls the NCR device 500A in cooperation with the gNB200 by establishing a wireless connection with the gNB200 and performing wireless communication with the gNB200. This enables efficient coverage expansion using the NCR device 500A. The NCR-MT 520A controls the NCR device 500A according to the control from the gNB200. Furthermore, the NCR-MT520A also has some of the same functions as the UE100.

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

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

[0038] In the example shown in Figure 5, the NCR device 500A (NCR-Fwd510A) dynamically or quasi-statically changes the beam being transmitted or received. For example, NCR-Fwd510A forms beams toward UE100a and UE100b, respectively. NCR-Fwd510A may also form a beam toward gNB200. For example, in a communication resource between gNB200 and UE100a, NCR-Fwd510A transmits a radio signal received from gNB200 toward UE100a by beamforming, and / or transmits a radio signal received from UE100a toward gNB200 by beamforming. The NCR-Fwd510A transmits radio signals received from gNB200 toward UE100b by beamforming, and / or transmits radio signals received from UE100b toward gNB200, in the communication resources between gNB200 and UE100b. In lieu of or in addition to beamforming, the NCR-Fwd510A may also perform null formation (so-called null steering) toward UE100 (not shown) and / or adjacent gNB200 (not shown) that are not communication partners, for interference suppression.

[0039] Figure 6 shows an example of a control method for the NCR device 500A according to the embodiment. As shown in Figure 6, the NCR-Fwd510A relays wireless signals (also referred to as "UE signals") between the gNB200 and the UE100. The UE signals include an uplink signal (also referred to as "UE-UL signal") transmitted from the UE100 to the gNB200 and a downlink signal (also referred to as "UE-DL signal") transmitted from the gNB200 to the UE100. The NCR-Fwd510A relays the UE-UL signal from the UE100 to the gNB200 and also relays the UE-DL signal from the gNB200 to the UE100. The wireless link between the NCR-Fwd510A and the UE100 is also referred to as the "access link". The wireless link between the NCR-Fwd510A and the gNB200 is also referred to as the "backhaul link".

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

[0041] Based on the NCR-MT-UL signal from NCR-MT520A, gNB200 directs its beam toward NCR-MT520A. Since NCR equipment 500A is co-located with NCR-MT520A, if the backhaul link and control link have the same frequency, when gNB200 directs its beam toward NCR-MT520A, the beam will also be directed toward NCR-Fwd510A. gNB200 uses this beam to transmit the NCR-MT-DL signal and the UE-DL signal. NCR-MT520A receives the NCR-MT-DL signal. If NCR-Fwd510A and NCR-MT520A are at least partially integrated, the functions for transmitting, receiving, or relaying the UE signal and / or NCR-MT signal (e.g., an antenna) may be integrated in both NCR-Fwd510A and NCR-MT520A. The term "beam" includes both the transmitting beam and / or the receiving beam. A beam is a general term for controlled transmission and / or reception aimed at maximizing the power of the transmitted and / or received waves in a specific direction by adjusting / adapting antenna weights, etc.

[0042] Figure 7 shows an example of the protocol stack configuration in a mobile communication system 1 having an NCR device 500A according to an embodiment. The NCR-Fwd510A relays radio signals transmitted and received between the gNB200 and the UE100. The NCR-Fwd510A has an RF (Radio Frequency) function that amplifies and relays the received radio signals and performs directional transmission by beamforming (for example, analog beamforming).

[0043] The NCR-MT520A has at least one layer (entity) among PHY, MAC, RRC, and F1-AP (Application Protocol). F1-AP is a type of fronthaul interface. The NCR-MT520A communicates with the gNB200 via signaling using at least one of PHY, MAC, RRC, and F1-AP. If the NCR-MT520A is a type or part of a base station, the NCR-MT520A may communicate with the gNB200 via an AP of Xn, which is an inter-base station interface (Xn-AP). The NCR-MT520A may also have a NAS layer (entity). The NAS layer allows the NCR-MT520A to communicate with the AMF300A via signaling. The NAS layer may constitute a higher layer for the NCR-MT520A.

[0044] Figure 8 shows a specific configuration example of a mobile communication system 1 having an NCR device 500A according to this embodiment.

[0045] 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 the 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 signals without demodulating or modulating them.

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

[0047] The gNB200 (transmitter 210) transmits an NCR control signal to the NCR-MT520A. The NCR control signal may be an RRC message, which is a control signal at the RRC layer (i.e., Layer 3). The NCR control signal may be a MAC CE (Control Element), which is a control signal at the MAC layer (i.e., Layer 2). The NCR control signal may be downlink control information (DCI), which is a control signal at the PHY layer (i.e., Layer 1). The NCR control signal may be UE individual signaling. The NCR control signal may be broadcast signaling. The NCR control signal may be a fronthaul message (e.g., an F1-AP message). If the NCR-MT520A is a type or part of a base station, the NCR-MT520A may communicate with the gNB200 via an AP (Xn-AP) of the inter-base station interface Xn.

[0048] In the following, NCR control signals transmitted in RRC messages (and / or MAC CEs) and used for static or quasi-static control of the NCR-Fwd510A are also referred to as "NCR configuration information" or simply "configuration information." Here, the RRC message may also be an RRC Reconfiguration message. The NCR configuration information may include, for example, information for setting the on / off state of the NCR-Fwd510A. The NCR configuration information may also include, for example, information for quasi-static beam settings of the NCR-Fwd510A.

[0049] On the other hand, the NCR control signals transmitted in L1 / L2 signaling, i.e., DCI (and / or MAC CE), and used for the dynamic control of the NCR-Fwd510A are also referred to as "NCR control information" or simply "control information." NCR control information may also be referred to as side control information (SCI). The CRC (Cyclic Redundancy Code) bits of the PDCCH carrying the NCR control information are scrambled by a newly introduced dedicated RNTI. This dedicated RNTI is also referred to as "NCR-RNTI." NCR control information may include, for example, information for the dynamic beam control of the NCR-Fwd510A. NCR setting information may include information instructing the dynamic on / off of the NCR-Fwd510A.

[0050] For example, when NCR-MT520A is in the RRC connected state, NCR device 500A can turn NCR-Fwd510A on or off according to the NCR control information (SCI) received from gNB200. On the other hand, after NCR-MT520A transitions to the RRC inactive state, NCR device 500A can turn NCR-Fwd510A on or off according to the latest (last) setting information received from gNB200.

[0051] The NCR control signals held by the NCR device 500A (NCR-MT520A) (for example, NCR setting information by RRC and / or NCR control information by L1 / L2 signaling) may also be referred to as the NCR-Fwd context.

[0052] Furthermore, if a wireless 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"). If the NCR-MT520A enters an RRC idle state because a suitable cell cannot be found during cell selection, the NCR device 500A turns off the NCR-Fwd510A. The NCR-Fwd510A remains off during the RRC connection re-establishment procedure.

[0053] The NCR control signal may include frequency control information that specifies the center frequency of the radio signal (e.g., component carrier) that the NCR-Fwd510A is to relay. If the NCR control signal received from the gNB200 includes frequency control information, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A to relay the radio signal with the center frequency indicated by the frequency control information (step S2A). The NCR control signal may include multiple frequency control information that specify different center frequencies. By including frequency control information in the NCR control signal, the gNB200 can specify the center frequency of the radio signal that the NCR-Fwd510A should relay via the NCR-MT520A.

[0054] The NCR control signal may include mode control information that specifies the operating mode of the NCR-Fwd510A. The mode control information may be associated with frequency control information (center frequency). The operating mode may be any of the following modes: a mode in which the NCR-Fwd510A performs omnidirectional transmission and / or reception; a mode in which the NCR-Fwd510A performs fixed directional transmission and / or reception; a mode in which the NCR-Fwd510A performs transmission and / or reception with a variable directional beam; or a mode in which the NCR-Fwd510A performs MIMO (Multiple Input Multiple Output) relay transmission. The operating mode may be either a beamforming mode (i.e., a mode that prioritizes desired wave improvement) or a null steering mode (i.e., a mode that prioritizes interference wave suppression). The NCR-MT520A (control unit 523) controls the NCR-Fwd510A to operate in the operating mode indicated by the mode control information if the NCR control signal received from the gNB200 includes mode control information (step S2A). By including mode control information in the NCR control signal, the gNB200 can specify the operating mode of the NCR-Fwd510A via the NCR-MT520A.

[0055] Here, the mode in which the NCR device 500A performs omnidirectional transmission and / or reception is the mode in which the NCR-Fwd510A performs omnidirectional relay, and may be called omnimode. The mode in which the NCR-Fwd510A performs fixed directional transmission and / or reception may be a directional mode realized by a single directional antenna. This mode may also be a beamforming mode realized by applying fixed phase and amplitude control (antenna weight control) to multiple antennas. Any of these modes may be specified (set) from the gNB200 to the NCR-MT520A. The mode in which the NCR-Fwd510A performs transmission and / or reception with a variable directional beam may be an analog beamforming mode. This mode may also be a digital beamforming mode. This mode may also be a hybrid beamforming mode. This mode may also be a mode that forms an adaptive beam specific to the UE100. Any of these modes may be specified (set) from the gNB200 to the NCR-MT520A. In addition, in the beamforming operation mode, beam control information described later may be provided from gNB200 to NCR-MT520A. The mode in which the NCR device 500A performs MIMO relay transmission may be a SU (Single-User) spatial multiplexing mode. This mode may also be a MU (Multi-User) spatial multiplexing mode. This mode may also be a transmit diversity mode. Any of these modes may be specified (set) from gNB200 to NCR-MT520A. The operation mode may include a mode that turns on (activates) relay transmission by NCR-Fwd510A and a mode that turns off (deactivates) relay transmission by NCR-Fwd510A. Any of these modes may be specified (set) from gNB200 to NCR-MT520A by NCR control signals.

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

[0057] The NCR control signal may include output control information that specifies the degree to which the NCR-Fwd510A amplifies the radio signal (amplification gain) or the transmit power. The output control information may also be information that indicates the difference (i.e., relative value) between the current amplification gain or transmit power and the target amplification gain or transmit power. If the NCR control signal received from the gNB200 includes output control information, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A to change to the amplification gain or transmit power indicated by the output control information. The output control information may be associated with frequency control information (center frequency). The output control information may also be information that specifies one of the amplifier gain, beamforming gain, or antenna gain of the NCR-Fwd510A. The output control information may also be information that specifies the transmit power of the NCR-Fwd510A.

[0058] When one NCR-MT520A controls multiple NCR-Fwd510A units, the gNB200 (transmitter 210) may transmit an NCR control signal to the NCR-MT520A for each NCR-Fwd510A unit. In this case, the NCR control signal may include the identifier of the corresponding NCR-Fwd510A unit (NCR identifier). The NCR-MT520A (control unit 523) controlling multiple NCR-Fwd510A units determines which NCR-Fwd510A unit to which the NCR control signal is applied based on the NCR identifier included in the NCR control signal received from the gNB200. Note that even when the NCR-MT520A controls only one NCR-Fwd510A unit, the NCR identifier may be transmitted from the NCR-MT520A to the gNB200 unit along with the NCR control signal.

[0059] In this way, the NCR-MT520A (control unit 523) controls the NCR-Fwd510A based on the NCR control signal from the gNB200. This allows the gNB200 to control the NCR-Fwd510A via the NCR-MT520A.

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

[0061] (1.3.1) Example of relay device configuration Figure 9 shows an example of the configuration of an NCR device 500A (relay device) according to this embodiment. The NCR device 500A includes an NCR-Fwd510A, an NCR-MT520A, and an interface 530.

[0062] The NCR-Fwd510A comprises a wireless unit 511A and an NCR control unit 512A. The wireless unit 511A includes an antenna section 511a containing multiple antennas (multiple antenna elements), an RF circuit 511b including an amplifier, and a directional control unit 511c that controls the directivity of the antenna section 511a. The RF circuit 511b amplifies and relays (transmits) the wireless signals transmitted and received by the antenna section 511a. The RF circuit 511b may convert the analog wireless signals into digital signals and then convert them back to analog signals after digital signal processing. The directional control unit 511c may perform analog beamforming by analog signal processing. The directional control unit 511c may perform digital beamforming by digital signal processing. The directional control unit 511c may perform hybrid analog and digital beamforming. The NCR control unit 512A controls the wireless unit 511A according to control signals from the NCR-MT520A. The NCR control unit 512A may include at least one processor.

[0063] The NCR-MT520A comprises a receiving unit 521, a transmitting unit 522, and a control unit 523. The receiving unit 521 performs various types of reception under the control of the control unit 523. The receiving unit 521 includes an antenna and a receiver. The receiver converts the radio signal (radio 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 types of transmission under the control of the control unit 523. The transmitting unit 522 includes an antenna and a transmitter. The transmitter converts the 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-MT520A. The operation of the NCR-MT520A (and NCR device 500A) described above and below may be 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, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processes. The control unit 523 also performs the functions of at least one layer of the PHY, MAC, RRC, and F1-AP.

[0064] Interface 530 electrically or logically connects the NCR-Fwd510A and the NCR-MT520A. The control unit 523 of the NCR-MT520A controls the NCR-Fwd510A via interface 530. Interface 530 may also be a logical entity at a higher layer (e.g., the application layer).

[0065] In this embodiment, the receiver 521 of the NCR-MT520A receives signaling (NCR control signal) used to control the NCR device 500A wirelessly from the gNB200. The control unit 523 of the NCR-MT520A controls the NCR device 500A based on this signaling. This enables the gNB200 to control the NCR-Fwd510A via the NCR-MT520A.

[0066] (1.3.2) Example of user device configuration Figure 10 shows the configuration of UE100 (user device) according to an embodiment. UE100 includes 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 gNB200.

[0067] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130.

[0068] The transmitting unit 120 performs various types of 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 wireless signal and transmits it from the antenna.

[0069] The control unit 130 performs various control and processing operations in the UE 100. Such processing includes processing in each layer described later. The operation of the UE 100 described above and later may also be 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 for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing operations.

[0070] (1.3.3) Example of base station configuration Figure 11 shows an example configuration of a gNB200 (base station) according to an embodiment. The gNB200 includes a transmitting unit 210, a receiving unit 220, a control unit 230, and a backhaul communication unit 240.

[0071] The transmitting unit 210 performs various types of transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts the 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 types of receptions under the control of the control unit 230. The receiving unit 220 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 230. The transmitting unit 210 and the receiving unit 220 may be capable of beamforming using multiple antennas.

[0072] The control unit 230 performs various controls on the gNB200. The operation of the gNB200 described above and below may also be 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 for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing.

[0073] The backhaul communication unit 240 is connected to an adjacent base station via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF300 via a base station-core network interface. The gNB may consist of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally separated), and the two units may be connected via an F1 interface.

[0074] In this embodiment, the gNB200's transmitter 210 transmits signaling (NCR control signals) used to control the NCR-MT520A to the NCR-MT520A via wireless communication. This enables the gNB200 to control the NCR device 500A via the NCR-MT520A.

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

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

[0077] In step S11, the NCR-MT520A performs frequency prioritization based on the frequency-specific priority (also referred to as "absolute priority," "cell reselection priority," or "dedicated priority") specified by the gNB200, for example, in a System Information Block (SIB) or RRC release message. Specifically, the NCR-MT520A manages the frequency priority specified by the gNB200 for each frequency.

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

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

[0080] (1.5) Operation according to the first embodiment The first embodiment relates to cell reselection of the NCR device 500A (NCR-MT520A) in an RRC inactive state or an RRC idle state.

[0081] Figure 13 is a diagram illustrating the operation according to the first embodiment. In the illustrated example, the NCR device 500A (NCR-MT520A) is, firstly, in an RRC connected state in cell a managed by gNB200a. Cell b adjacent to cell a is managed by gNB200b, which is different from gNB200a. However, cells a and b may be managed by the same gNB200. The NCR device 500A (NCR-MT520A) is assumed to be performing relay operations according to the NCR control signal received from cell a (gNB200a) (i.e., NCR-Fwd510A is on).

[0082] Secondly, the NCR-MT520A receives an RRC Release message containing a suspend setting from cell a (gNB200) and transitions to the RRC inactive state. In the RRC inactive state, the NCR-MT520A keeps the NCR-Fwd510A on according to the latest NCR control signals (in particular, NCR setting information) received from gNB200. This operation may apply not only to the RRC inactive state but also to the RRC idle state.

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

[0084] In this scenario, it is necessary to clarify how the NCR device 500A operates. There are two possible options:

[0085] Option 1: NCR-Fwd510A will remain enabled with the latest NCR configuration information.

[0086] Option 2: NCR-Fwd510A is turned off. The NCR device 500A may discard the latest NCR configuration information.

[0087] Option 1 is preferable from the standpoint of simplifying the operation of the NCR-MT520A. However, it can be problematic if the latest NCR configuration information is provided by cell a (i.e., the last serving cell), and the NCR-Fwd510A operates according to that configuration information in another cell b. For example, the re-selected cell b may have a different set of resources available to the NCR device 500A. Therefore, from the standpoint of technical rationality, option 2 is more desirable.

[0088] In the first embodiment, when the NCR-MT520A is in an RRC idle or RRC inactive state in a first cell (e.g., cell a) and the NCR-Fwd510A is on, the NCR-MT520A performs cell reselection to a second cell (e.g., cell b) different from the first cell. The NCR device 500A (NCR-MT520A) turns off the NCR-Fwd510A based on the cell reselection from the first cell to the second cell. That is, if the NCR-MT520A reselects a different cell, the NCR device 500A controls the NCR-Fwd510A to turn off.

[0089] When NCR-MT520A is in an RRC idle or RRC inactive state in the first cell, NCR device 500A (NCR-MT520A) may retain the NCR control signal (latest NCR control signal) received from the first cell. NCR-MT520A may discard the retained latest NCR control signal (also referred to as the "NCR-Fwd context") in response to cell reselection from the first cell to the second cell.

[0090] After re-selecting the cell from the first cell to the second cell, the NCR-MT520A may transition to the RRC connected state in the second cell in order to acquire NCR control signals from the second cell. For example, an NCR-MT520A in the RRC idle state in the second cell will transition to the RRC connected state via the RRC connection establishment procedure. An NCR-MT520A in the RRC inactive state in the second cell will transition to the RRC connected state via the RRC connection recovery procedure. An NCR-MT520A that has transitioned to the RRC connected state in the second cell will receive new NCR control signals related to relay operation from the second cell. The NCR device 500A will then control the relay operation based on the NCR control signals received from the second cell. In the following, the RRC connection establishment procedure and the RRC connection recovery procedure may be collectively referred to as the "RRC connection procedure".

[0091] Figure 14 shows an example of the operation of the NCR device 500A according to the first embodiment.

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

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

[0094] In step S103, if the NCR-MT520A is in an RRC idle or RRC inactive state in cell a, it re-selects cell b through cell re-selection. Cell b is a different cell from the current cell a, and is a different cell from cell a to which the above latest settings (and control) were performed. Cell b may also be a different cell from the desired cell to which the NCR device 500A should be connected according to the site design (communication service area design).

[0095] In step S104, NCR-MT520A controls NCR-Fwd510A to turn off due to the re-selection of cell b. NCR-MT520A may discard the most recent NCR control signal it holds.

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

[0097] The NCR-MT520A may initiate the RRC connection procedure for cell b only if at least one of the following conditions 1 and 2 is met.

[0098] Condition 1: Cell b is the desired cell. In other words, assuming that one or more cells to which the NCR-MT520A should be connected have been determined in the station design, this condition means that it corresponds to one of those predetermined cells.

[0099] Condition 2: Cell b has sent an SIB1 containing information indicating support for an NCR device (NCR Support IE).

[0100] When NCR-MT520A transitions to the RRC connected state in cell b, it receives a new NCR control signal from cell b and controls NCR-Fwd510A (for example, turns it on) according to the received NCR control signal.

[0101] (1.6) First modification example of the first embodiment The first modification example of the first embodiment will be described primarily in terms of the differences from the first embodiment described above.

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

[0103] NCR-MT520A receives setting information (also referred to as "on / off setting information") from cell a (gNB200) to specify whether or not to turn off NCR-Fwd510A when cell reselection occurs. If the on / off setting information indicates that NCR-Fwd510A should be turned off when cell reselection occurs, NCR device 500A turns off NCR-Fwd510A in response to cell reselection to cell b.

[0104] Figure 15 shows an example of the operation of the NCR device 500A according to the first modification example of the first embodiment. Here, we will mainly explain the differences from the first embodiment described above, and omit redundant explanations.

[0105] In step S131, the NCR-MT520A, which is in an RRC connected state in cell a, receives an NCR control signal from cell a (gNB200) and turns on the NCR-Fwd510A according to the NCR control signal. The NCR control signal may include on / off setting information. Alternatively, the on / off setting information may be broadcast in the SIB in cell a. The NCR-MT520A receives the on / off setting information. The on / off setting information may include a setting on whether or not the NCR-Fwd510A may operate as a conventional RF repeater (i.e., an RF repeater that does not depend on network control) when it is kept on. If the NCR device 500A has multiple NCR-Fwd510A units (i.e., the NCR-MT520A handles multiple NCR-Fwd510A units), the on / off setting information may include information on setting the on / off status for each of the multiple NCR-Fwd510A units when cell re-selection occurs.

[0106] In step S132, NCR-MT520A transitions to either the RRC idle state or the RRC inactive state. NCR-Fwd510A is assumed to be ON-controlled according to the latest NCR control signal. NCR-MT520A retains the latest NCR control signal.

[0107] In step S133, if the NCR-MT520A has transitioned to the RRC idle state or RRC inactive state in cell a, it re-selects cell b by re-selecting the cell.

[0108] In step S134, the NCR-MT520A determines whether the on / off setting information set by cell a(gNB200) indicates that the NCR-Fwd510A is off. If the NCR device 500A has multiple NCR-Fwd510A units, the determination in step S134 may be performed for each of the multiple NCR-Fwd510A units.

[0109] If the on / off setting information indicates that NCR-Fwd510A is off (step S134: YES), in step S135, NCR-MT520A controls NCR-Fwd510A to be off due to the re-selection of cell b. NCR-MT520A may discard the most recent NCR control signal it holds. The operation in step S136 is the same as in the first embodiment described above.

[0110] If the on / off setting information indicates that NCR-Fwd510A is ON (step S134: NO), in step S137, NCR-MT520A will keep NCR-Fwd510A ON even if cell b is re-selected. NCR device 500A may operate NCR-Fwd510A as a conventional RF repeater.

[0111] (1.7) Second modification example of the first embodiment The second modification of the first embodiment will be described primarily in terms of the differences from the first embodiment described above. This modification may be implemented in combination with the first modification described above.

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

[0113] Area information may be information for identifying the gNB200, such as the gNB ID or any ID for identifying the gNB (for example, a part of the gNB ID may be used (in an abbreviated form), or a different number format may be used). This identification information may be broadcast by the gNB200 via SIB, and the UE100 may use this broadcast information to determine whether the cell re-established in the RRC belongs to an active area.

[0114] In this modified example, NCR-MT520A receives an NCR control signal from cell a (gNB200) that includes information indicating that NCR-Fwd510A should be turned on, and area information indicating the area where the information is valid. If cell b does not belong to the valid area, NCR device 500A turns off NCR-Fwd510A in response to cell reselection to cell b. On the other hand, if cell b does belong to the valid area, NCR-Fwd510A remains on even if cell reselection to cell b is performed.

[0115] Figure 16 shows an example of the operation of the NCR device 500A according to the second modification of the first embodiment. Here, we will mainly explain the differences from the first embodiment described above, and omit redundant explanations.

[0116] In step S151, the NCR-MT520A, which is in the RRC connected state in cell a, receives an NCR control signal from cell a (gNB200) and turns on the NCR-Fwd510A according to the NCR control signal. The NCR control signal includes area information indicating the effective area. This effective area may be set commonly for the NCR setting information and the NCR control information, or it may be set separately.

[0117] In step S152, NCR-MT520A transitions to either the RRC idle state or the RRC inactive state. NCR-Fwd510A is assumed to be ON-controlled according to the latest NCR control signal. NCR-MT520A retains the latest NCR control signal.

[0118] In step S153, if NCR-MT520A has transitioned to an RRC idle state or RRC inactive state in cell a, it re-selects cell b by cell re-selection. NCR-MT520A may also notify the upper layer that it has re-selected cell b.

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

[0120] If it is determined that cell b belongs to the effective area (step S154: YES), in step S155, the NCR device 500A (NCR-MT520A) turns on the NCR-Fwd510A according to the latest NCR control signal.

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

[0122] (1.8) Third modification of the first embodiment The third modification of the first embodiment will be described primarily in terms of its differences from the first embodiment described above. This modification may be implemented in combination with the modification described above.

[0123] The above-mentioned effective area may be determined by negotiation between gNB200s. For example, a gNB200 transmits an NCR control signal (NCR setting information) to be set on its own cell's NCR device 500A to an adjacent gNB. If the adjacent gNB determines that the NCR control signal can also be applied to its own cell, it may permit its own cell to be included in the effective area of ​​the NCR control signal.

[0124] For example, gNB200b, which manages cell b, obtains NCR setting information that gNB200a sets on the NCR device 500A from gNB200a, which manages cell a. Based on the obtained NCR setting information, gNB200b may send a notification to gNB200a indicating the result of determining whether the NCR setting information is valid in cell b. If the NCR setting information obtained from gNB200a is also valid in cell b, gNB200b can omit setting the NCR setting information on the NCR-MT520A.

[0125] For example, if cell b also relays the same resources as cell a, or if the NCR device 500A located in cell b relays the wireless signal from cell a, it may be determined that the NCR configuration information obtained from gNB200a is also valid in cell b.

[0126] Figure 17 shows an example of the operation of the mobile communication system 1 according to the third modification of the first embodiment. Here, we will mainly explain the differences from the first embodiment described above, and omit redundant explanations. Communication between gNB200a and gNB200b is assumed to take place, for example, over the Xn interface. Furthermore, NCR-MT520A is connected to cell a and controls NCR-Fwd510A according to the NCR control signal from cell a.

[0127] In step S171, gNB200b may query gNB200a for NCR setting information of NCR device 500A located in cell a. At this point, NCR device 500A does not need to have moved to cell b yet.

[0128] In step S172, gNB200a sends an Xn message (e.g., a gNB Configuration Update message) containing NCR configuration information to gNB200b. This NCR configuration information may be communicated as a combination of the identifier of the NCR device 500A and the NCR configuration information (e.g., in list format).

[0129] In step S173, gNB200b may determine, based on the NCR setting information from gNB200a, whether or not the NCR setting information can be reused in its own cell (cell b), and notify gNB200a of the result. Here, we will proceed with the explanation assuming that the NCR setting information can be reused in cell b.

[0130] gNB200a may set an area where the current NCR setting information can continue to be applied to NCR-MT520A (see the second modification example). Based on this setting, NCR device 500A will control NCR-Fwd510A according to the current NCR setting information even after re-selecting cell b.

[0131] Alternatively, a scenario may be considered in which the NCR device 500A is handed over from cell a to cell b. If gNB200a has already notified gNB200b of the NCR configuration information when it decides to perform the handover, or has confirmed that the NCR configuration information can be reused, it does not need to include the NCR configuration information in the handover request message sent to gNB200b. Furthermore, when determining the target cell for the handover, gNB200a may prioritize other cells from which the NCR configuration information can be reused and determine them as the target cell.

[0132] (2) Second Embodiment The second embodiment will be described primarily in terms of its differences from the first embodiment. The first embodiment and its modifications may be implemented in combination with the second embodiment.

[0133] The second embodiment follows the same basic assumed scenario as the first embodiment. However, in the second embodiment, instead of turning off the NCR-Fwd510A triggered by cell reselection as in the first embodiment, the NCR-Fwd510A is turned off triggered by the start of the RRC connection procedure.

[0134] In other words, in the second embodiment, when NCR-MT520A is in an RRC idle state or RRC inactive state in the first cell and NCR-Fwd510A is on, NCR-MT520A initiates an RRC connection procedure (RRC connection establishment procedure or RRC connection recovery procedure) for the second cell to transition to an RRC connected state. Based on the initiation of the RRC connection procedure, NCR device 500A turns off NCR-Fwd510A. In the second embodiment, the second cell is the target cell for RRC connection establishment or RRC connection recovery.

[0135] However, in the second embodiment, if the second cell is the same cell as the first cell, the NCR device 500A may keep the NCR-Fwd510A turned on even after starting the RRC connection procedure.

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

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

[0138] Secondly, NCR-MT520A receives an RRC Release message from cell a (gNB200) that includes a suspend setting and transitions to the RRC inactive state. In the RRC inactive state, NCR-MT520A keeps NCR-Fwd510A on according to the latest NCR control signals (in particular, NCR setting information) received from gNB200.

[0139] Thirdly, after the NCR-MT520A transitions to an RRC inactive state in cell a, the NCR-MT520A re-selects another cell b, for example, due to FR2 blocking. In the second embodiment, the NCR device 500A keeps the NCR-Fwd510A on instead of turning it off at the time of cell re-selection. However, the NCR device 500A may operate the NCR-Fwd510A as a conventional RF repeater.

[0140] Fourth, NCR-MT520A, having re-selected cell b in the RRC inactive state, initiates the RRC connection recovery procedure with cell b. NCR device 500A turns off NCR-Fwd510A based on the initiation of the RRC connection recovery procedure. NCR-MT520A, having transitioned to the RRC connected state in cell b, receives a new NCR control signal from cell b and controls NCR-Fwd510A (e.g., turns it on) according to the newly received NCR control signal.

[0141] Figure 19 is a diagram illustrating another example of operation according to the second embodiment. In the illustrated example, the NCR-MT520A restores the RRC connection with the original cell a without performing cell reselection.

[0142] Firstly, the NCR device 500A (NCR-MT520A) is in an RRC connected state in cell a managed by gNB200a. The NCR device 500A (NCR-MT520A) is performing relay operations according to the NCR control signal received from cell a (gNB200a) (i.e., NCR-Fwd510A is on).

[0143] Secondly, NCR-MT520A receives an RRC Release message from cell a (gNB200) that includes a suspend setting and transitions to the RRC inactive state. While NCR-MT520A is in the RRC inactive state, NCR device 500A keeps NCR-Fwd510A on according to the latest NCR control signals (in particular, NCR setting information) received from gNB200.

[0144] Thirdly, the NCR-MT520A, in an RRC inactive state, initiates the RRC connection recovery procedure with cell a. In this case, the NCR device 500A keeps the NCR-Fwd510A on even after initiating the RRC connection recovery procedure.

[0145] Figure 20 shows an example of the operation of the NCR device 500A according to the second embodiment. Here, we will mainly explain the differences from the first embodiment described above, and omit redundant explanations.

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

[0147] In step S202, the NCR-MT520A transitions to the RRC inactive state. The NCR-MT520A retains the latest NCR control signal. For example, the NCR-MT520A retains information indicating that the NCR-MT520A is ON (NCR setting information or NCR control information). The NCR device 500A keeps the NCR-Fwd510A ON according to the latest NCR control signal.

[0148] An NCR-MT520A in an RRC idle or RRC inactive state in the first cell may re-select a different cell as the second cell. Alternatively, the NCR-MT520A may maintain the same cell as the first cell as the second cell without re-selecting a cell.

[0149] In step S203, the NCR-MT520A initiates the RRC connection recovery procedure for the second cell. For example, the NCR-MT520A sends an RRC recovery request procedure to the second cell.

[0150] Furthermore, the NCR-MT520A may initiate the RRC connection procedure for the second cell only if at least one of the following conditions 1 and 2 is met.

[0151] Condition 1: The second cell is the desired cell. In other words, assuming that one or more cells to which the NCR-MT520A should be connected are determined in the station design, this condition means that the NCR-MT520A corresponds to one of those predetermined cells.

[0152] Condition 2: The second cell is transmitting an SIB1 containing information indicating support for an NCR device (NCR Support IE).

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

[0154] If it is determined that the second cell is a different cell from the first cell (step S204: NO), in step S205, the NCR device 500A (NCR-MT520A) controls the NCR-Fwd510A to turn off as it has started the RRC connection recovery procedure. The NCR-MT520A may discard the most recent NCR control signal it holds. In this case, the NCR-MT520A may, after transitioning to the RRC connected state in the second cell, receive a new NCR control signal from the second cell and control the NCR-Fwd510A (for example, turn it on) according to the received NCR control signal.

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

[0156] This example describes the operation when NCR-MT520A transitions from the RRC inactive state to the RRC connected state. However, the operation when NCR-MT520A transitions from the RRC idle state to the RRC connected state may be the same as the operation in Figure 20. Alternatively, the operation when NCR-MT520A transitions from the RRC idle state to the RRC connected state may differ in part from the operation in Figure 20. When NCR-MT520A is in the RRC idle state, there is a concern that gNB200 may not have the context of NCR device 500A, and continuing on control is undesirable. Therefore, as shown in Figure 21, when NCR-MT520A transitions from the RRC idle state to the RRC connected state, NCR device 500A may uniformly turn off NCR-Fwd510A, regardless of whether it is the same cell or not, upon the start of the RRC connection establishment procedure.

[0157] Furthermore, the second embodiment is also applicable to the modifications described above for the first embodiment.

[0158] For example, similar to the first modification of the first embodiment, the NCR control signal may include on / off setting information indicating whether or not the NCR-Fwd510A should be turned off when the RRC connection is restored. Alternatively, the on / off setting information may be broadcast in the SIB in cell a. The NCR-MT520A receives the on / off setting information. The on / off setting information may include a setting indicating whether or not the NCR-Fwd510A may operate as a conventional RF repeater (i.e., an RF repeater independent of network control) when it is kept on. In the case where the NCR device 500A has multiple NCR-Fwd510A (i.e., the NCR-MT520A handles multiple NCR-Fwd510A), the on / off setting information may include information to set the on / off status for each of the multiple NCR-Fwd510A when the RRC connection is restored. For example, NCR-MT520A may receive on / off setting information from cell a to specify whether or not to turn off NCR-Fwd510A during the RRC connection recovery procedure. If the on / off setting information indicates that NCR-Fwd510A should be turned off during the RRC connection recovery procedure, NCR device 500A may turn off NCR-Fwd510A in response to the start of the RRC connection recovery procedure. Note that the on / off setting information may also be broadcast via SIB from cell b (gNB200b).

[0159] Similar to the second modification of the first embodiment, the NCR control signal may include setting information indicating that the NCR-Fwd510A should be turned on, and area information indicating the area where the setting information is valid. The NCR device 500A may turn off the NCR-Fwd510A in response to the start of the RRC connection recovery procedure if cell b does not belong to the valid area. The NCR device 500A may keep the NCR-Fwd510A turned on even when the RRC connection recovery procedure is started if cell b belongs to the valid area.

[0160] Similar to the third modification example of the first embodiment, gNB200b, which manages cell b, may obtain setting information that gNB200a sets on the NCR device 500A from gNB200a, which manages cell a.

[0161] (3) Third Embodiment Next, the differences between the third embodiment and the embodiments described above will be explained. As shown in Figure 22, the relay device according to the third embodiment is a RIS (Reconfigurable Intelligent Surface) device 500B that changes the propagation direction of incident radio waves (wireless signals) by reflection or refraction. "NCR" in the embodiments described above can be read as "RIS".

[0162] RIS is a type of repeater (hereinafter also referred to as "RIS-Fwd") that can perform beamforming (directivity control) similar to NCR by changing the properties of the metamaterial. In the case of RIS, the beam range (distance) may also be changed by controlling the reflection direction and / or refraction direction of each unit element. For example, in addition to controlling the reflection direction and / or refraction direction of each unit element, it may be possible to configure it to focus on (direct the beam towards) a nearby UE or to focus on (direct the beam towards) a distant UE.

[0163] The RIS device 500B has a new UE (hereinafter referred to as "RIS-MT") 520B, which is a control terminal for controlling the RIS-Fwd510B. The RIS-MT 520B controls the RIS-Fwd510B in cooperation with the gNB200 by establishing a wireless connection with the gNB200 and performing wireless communication with the gNB200. The RIS-Fwd510B may be a reflective type RIS. Such a RIS-Fwd510B changes the propagation direction of radio waves by reflecting the incident radio waves. Here, the reflection angle of the radio waves is variable. The RIS-Fwd510B reflects the radio waves incident from the gNB200 toward the UE 100. The RIS-Fwd510B may also be a transmissive type RIS. Such a RIS-Fwd510B changes the propagation direction of radio waves by refracting the incident radio waves. Here, the refraction angle of the radio waves is variable.

[0164] Figure 23 shows an example configuration of the RIS-Fwd (repeater) 510B and RIS-MT (control terminal) 520B according to the third embodiment. The RIS-MT 520B has a receiving unit 521, a transmitting unit 522, and a control unit 523. This configuration is the same as that of the embodiment described above. The RIS-Fwd 510B has a RIS 511B and a RIS control unit 512B. The RIS 511B is a metasurface constructed using metamaterials. For example, the RIS 511B is constructed by arranging very small structures in an array relative to the wavelength of radio waves, and by making the shape of the structures different depending on the arrangement location, it is possible to arbitrarily design the direction of the reflected wave and / or the beam shape. The RIS 511B may also be a transparent dynamic metasurface. RIS511B is constructed by layering a transparent glass substrate on top of a metasurface substrate, which has a large number of small structures arranged regularly. By moving the layered glass substrate slightly, it may be possible to dynamically control three patterns: a mode in which incident radio waves are transmitted, a mode in which some radio waves are transmitted and some are reflected, and a mode in which all radio waves are reflected. The RIS control unit 512B controls RIS511B in accordance with the RIS control signal from the control unit 523 of RIS-MT520B. The RIS control unit 512B may include at least one processor and at least one actuator. The processor decodes the RIS control signal from the control unit 523 of RIS-MT520B and drives the actuator in accordance with the RIS control signal.

[0165] (4) Other embodiments In the first embodiment described above, an example was described in which an NCR-MT520A in an RRC inactive state or an RRC idle state performs cell reselection. In the second embodiment described above, an example was described in which an NCR-MT520A in an RRC inactive state or an RRC idle state performs an RRC connection procedure (RRC connection recovery procedure or RRC connection establishment procedure). However, the operations relating to the above embodiments and their modifications may also be applied to a handover performed by an NCR-MT520A in an RRC connected state. For example, the cell reselection in the first embodiment described above may be read as a handover. The RRC connection procedure (RRC connection recovery procedure or RRC connection establishment procedure) in the second embodiment described above may also be read as a handover.

[0166] In the above-described embodiment, an example was given in which the relay device performing relay transmission is an NCR device 500A or a RIS device 500B. However, the relay device performing relay transmission is not limited to an NCR device 500A or a RIS device 500B, but may also be an IAB (Integrated Access and Backhaul) node as defined in the 3GPP technical specifications.

[0167] Each of the above-described operation flows can be performed not only independently, but also in combination of 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. It is not necessary to execute all steps in each flow; only some steps may be executed.

[0168] In the above embodiment, an example was described in which the base station is an NR base station (gNB), but the base station may also be an LTE base station (eNB). Furthermore, the base station may be a relay node such as an IAB node. The base station may also be a DU (Distributed Unit) of an IAB node. Additionally, UE100 may be an MT (Mobile Termination) of an IAB node.

[0169] Furthermore, 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). Additionally, a network node may consist of a combination of at least a part of the core network device and at least a part of a base station.

[0170] A program may be provided that causes a computer to execute each of the processes performed by the communication device according to the above embodiment, for example, UE100 (NCR-MT520A, RIS-MT520B), gNB200, or relay device. The program may be recorded on a computer-readable medium. Using a 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, but may be a recording medium such as a CD-ROM or DVD-ROM. Furthermore, the circuits that execute each of the processes performed by UE100, gNB200, or relay device may be integrated, and at least a part of UE100, gNB200, or relay device may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0171] The functions realized by 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 (a Central Processing Unit), conventional circuits, and / or combinations thereof, programmed to realize the described functions. A processor, including transistors and other circuits, is considered circuitry or processing circuitry. A processor may be a programmed processor that executes a program stored in memory. In this specification, circuitry, unit, and means are hardware programmed to realize or perform the described functions. Such hardware may be any hardware disclosed herein, or any hardware known to be programmed to realize or perform the described functions. If such hardware is a processor that is considered to be of the type of circuitry, such circuitry, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0172] The phrases “based on” and “depending on / in response to” used in this disclosure do not mean “based solely on” or “depending solely on” unless otherwise specified. “Based on” means both “based solely on” and “at least partially on.” Similarly, “depending on” means both “at least partially on” and “at least partially on.” The terms “include,” “comprise,” and variations thereof do not mean that only the listed items are included; they mean that only the listed items may be included, or that additional items may be included in addition to the listed items. Furthermore, the term “or” used in this disclosure is not intended to mean exclusive OR. Additionally, any reference to elements using designations such as “first,” “second,” etc., used in this disclosure does not 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. Therefore, references to the first and second elements do not imply that only two elements may be adopted therein, or that the first element must precede the second element in any way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall be plural unless it is clearly indicated by the context that they are not.

[0173] Although the embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to those described above, and various design changes can be made without departing from the gist of the invention.

[0174] This application claims priority to Japanese Patent Application No. 2023-019937 (filed February 13, 2023), and all of its contents are incorporated into the specification of this application.

[0175] (5) Note The features of the above-described embodiment are noted below.

[0176] (Note 1) A communication method using a relay device comprising: a relay device that performs relay operations to relay wireless signals transmitted between a network and a user device; and a control terminal that receives control signals from the network to be used to control the relay device, When the control terminal is in a Radio Resource Control (RRC) idle state or RRC inactive state in the first cell and the repeater is on, the control terminal initiates a procedure for transitioning to an RRC connected state for the second cell. The relay device has the step of turning off the relay device based on the start of the procedure. Communication method.

[0177] (Note 2) The aforementioned initiation step includes the step of the control terminal in the RRC inactive state initiating the RRC connection recovery procedure as the procedure, The step of turning off includes turning off the repeater based on the initiation of the RRC connection recovery procedure. The communication method described in Appendix 1.

[0178] (Note 3) The step of turning it off includes, if the second cell is a different cell from the first cell, turning off the relay in response to the start of the procedure. The communication method described in Appendix 1 or 2.

[0179] (Note 4) If the second cell is the same cell as the first cell, the procedure further includes the step of keeping the repeater turned on even when the procedure is started. The communication method described in any of the appendices 1 to 3.

[0180] (Note 5) The control terminal further includes the step of receiving setting information from the first cell to specify whether or not to turn off the relay during the procedure, The step of turning it off includes, if the configuration information indicates that the repeater should be turned off during the procedure, the step of turning off the repeater in response to the start of the procedure. The communication method described in any of the appendices 1 to 4.

[0181] (Note 6) The control signal includes setting information indicating that the repeater should be turned on, and area information indicating the area where the setting information is valid. The step of turning it off includes, if the second cell does not belong to the effective area, turning off the relay in response to the start of the procedure. The communication method described in any of the appendices 1 to 5.

[0182] (Note 7) The second network node managing the second cell further includes the step of obtaining configuration information that the first network node sets in the relay device from the first network node managing the first cell. The communication method described in any of the appendices 1 to 6.

[0183] (Note 8) A relay device that performs relaying operations to relay wireless signals transmitted between the network and user equipment, The system includes a control terminal that receives control signals used for controlling the relay from the network, The aforementioned control terminal is When the first cell is in a Radio Resource Control (RRC) idle state or RRC inactive state, and the repeater is on, a procedure is initiated for the second cell to transition to the RRC connected state. Based on the commencement of the procedure, the repeater is turned off. Relay device. [Explanation of symbols]

[0184] 1: Mobile communication systems 100:UE 200:gNB 210: Transmitter 220: Receiver 230: Control Unit 240: Backhaul Communications Department 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: Directional control unit 512A: NCR Control Unit 512B: RIS Control Unit 521: Receiving Unit 522: Transmitter 523: Control Unit 530: Interface

Claims

1. A communication method using a repeater node having a repeater device configured to perform the transfer operation of wireless signals transmitted between a network and a user device, and a control terminal that supports the functions of the user device, When the control terminal transitions from a wireless resource control (RRC) connected state to an RRC inactive state, the transfer operation is to be continued by the repeater device. If the control terminal, which is in the RRC inactive state in the first cell, selects a second cell different from the first cell, the repeater device will stop the transfer operation. Communication method.

2. A repeater node comprising a repeater device configured to perform the transfer operation of wireless signals transmitted between a network and a user device, and a control terminal that supports the functions of the user device, The control terminal has a control unit and a receiving unit, The control unit, When transitioning from a Wireless Resource Control (RRC) connected state to an RRC inactive state, the repeater device is instructed to continue the transmission operation. If a second cell different from the first cell is selected while the RRC is inactive in the first cell, the repeater device will stop the transfer operation. Repeater node.

3. A repeater node having a repeater device configured to perform the transfer operation of wireless signals transmitted between a network and a user device, and a control terminal that supports the functions of the user device, When transitioning from a Wireless Resource Control (RRC) connected state to an RRC inactive state, the process involves continuing the transmission operation on the repeater device. When the RRC is inactive in the first cell, and a second cell different from the first cell is selected, the repeater device is instructed to perform a process to stop the transfer operation. program.

4. A chipset for a repeater node having a repeater device configured to perform the transfer operation of wireless signals transmitted between a network and a user device, and a control terminal that supports the functions of the user device, When transitioning from a Wireless Resource Control (RRC) connected state to an RRC inactive state, the process involves continuing the transmission operation on the repeater device. When the RRC is inactive in the first cell, and a second cell different from the first cell is selected, the repeater device is instructed to perform a process to stop the transfer operation. Chipset.

5. A system including a network, user equipment, and repeater nodes, The repeater node comprises a repeater device configured to perform the transfer operation of wireless signals transmitted between the network and the user device, and a control terminal that supports the functions of the user device. The control terminal has a control unit and a receiving unit, The control unit, When transitioning from a Wireless Resource Control (RRC) connected state to an RRC inactive state, the repeater device is instructed to continue the transmission operation. If a second cell different from the first cell is selected while the RRC is inactive in the first cell, the repeater device will stop the transfer operation. system.

6. A user device that controls a repeater device configured to perform the transfer operation of wireless signals transmitted between a network and a user device, The user device has a control unit and a receiving unit, The control unit, When transitioning from the Wireless Resource Control (RRC) connected state to the RRC inactive state, the repeater device continues the transmission operation. When the RRC is inactive in the first cell, if a second cell different from the first cell is selected, the transfer operation by the repeater device is stopped. User device.

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