COMMUNICATION CONTROL METHOD, FIRST DEVICE, NETWORK NODE, CHIP SET, PROGRAM, AND MOBILE COMMUNICATION SYSTEM

Abstract

To provide a mobile communication system that includes a base station that expands coverage by dynamically changing a propagation direction of radio waves incident from the base station through reflection or refraction, and a wireless terminal that performs wireless communication with the base station.SOLUTION: In a mobile communication system including a gNB200 and UE that performs wireless communication with the gNB200, a Reconfigurable Intelligent Surface (RIS)-UE100B that controls a RIS device 500 that uses a metasurface technology to change a propagation direction of radio waves incident from the gNB200 extends the coverage of a base station. When the gNB200 is congested, the gNB200 broadcasts access restriction information that restricts access from the UE100, but since the RIS-UE100B can be regarded as an entity on the network side, the RIS-UE100B ignores the access restriction information from the gNB200.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a communication control method, a wireless terminal, and a base station used in a mobile communication system. [Background technology]

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

[0003] Radio waves in high frequency bands such as millimeter waves or terahertz waves have a tendency to propagate in a very straight line, which poses a problem of reducing the coverage of base stations. To solve this problem, RIS (Reconfigurable Intelligent Surface) devices using metasurface technology have attracted attention (see, for example, Non-Patent Document 1). Such RIS devices can expand the coverage of base stations by dynamically changing the propagation direction of radio waves (beams) incident from the base station, for example, by reflection or refraction. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP contribution: RP-210618, “Support of Reconfigurable Intelligent Surface for 5G Advanced” Summary of the Invention

[0005] A communication control method according to a first aspect is a method used in a mobile communication system including a base station and a wireless terminal that performs wireless communication with the base station. The communication control method includes the steps of: a RIS (Reconfigurable Intelligent Surface) wireless terminal, which is the wireless terminal that controls a RIS device that changes the propagation direction of radio waves incident from the base station, establishing a wireless connection with the base station; and a step of the RIS wireless terminal transmitting RIS device information indicating at least one of the capabilities of the RIS device and the control state of the RIS device to the base station via the wireless communication.

[0006] A wireless terminal according to a second aspect is a device that performs wireless communication with a base station in a mobile communication system, and includes: a control unit that controls a Reconfigurable Intelligent Surface (RIS) device that changes the propagation direction of radio waves incident from the base station; and a transmission unit that transmits RIS device information indicating at least one of the capabilities of the RIS device and the control state of the RIS device to the base station via the wireless communication.

[0007] A base station according to a third aspect is a device that performs wireless communication with a wireless terminal in a mobile communication system, and includes a receiving unit that receives, via wireless communication, RIS device information indicating at least one of the capabilities of a Reconfigurable Intelligent Surface (RIS) device and a control state of the RIS device from the wireless terminal that controls the RIS device, the RIS device changing the propagation direction of radio waves incident from the base station. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. [Figure 2] FIG. 10 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data. [Figure 3]FIG. 1 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals). [Figure 4] FIG. 1 is a diagram illustrating an application scenario of a RIS device according to an embodiment. [Figure 5] FIG. 1 is a diagram illustrating an application scenario of a RIS device according to an embodiment. [Figure 6] FIG. 1 is a diagram illustrating an application scenario of a RIS device according to an embodiment. [Figure 7] FIG. 1 is a diagram illustrating an application scenario of a RIS device according to an embodiment. [Figure 8] FIG. 1 is a diagram illustrating the configuration of a RIS-UE (RIS wireless terminal) and a RIS device according to an embodiment. [Figure 9] A diagram showing the configuration of a gNB (base station) according to one embodiment. [Figure 10] A diagram showing downlink signaling from a gNB to a RIS-UE in one embodiment. [Figure 11] FIG. 10 is a diagram illustrating the configuration of RIS control settings according to one embodiment. [Figure 12] FIG. 10 is a diagram illustrating the configuration of RIS control settings according to one embodiment. [Figure 13] A diagram showing uplink signaling from a RIS-UE to a gNB according to one embodiment. [Figure 14] FIG. 10 is a diagram showing the configuration of RIS device capability information according to an embodiment. [Figure 15] FIG. 10 is a diagram showing the configuration of RIS device capability information according to an embodiment. [Figure 16] FIG. 10 is a diagram illustrating a configuration of control status information according to an embodiment. [Figure 17] FIG. 10 is a diagram illustrating a configuration of control status information according to an embodiment. [Figure 18] FIG. 10 illustrates operations related to measurements by a RIS-UE according to one embodiment. [Figure 19] FIG. 10 is a diagram illustrating an operation according to the first embodiment. [Figure 20] FIG. 10 is a diagram illustrating an operation according to the second embodiment. [Figure 21] FIG. 10 is a diagram showing an example of the configuration of RIS control setting and control timing information according to the second embodiment. [Figure 22] FIG. 10 is a diagram illustrating an operation according to the third embodiment. [Figure 23] FIG. 10 is a diagram illustrating an operation according to the fourth embodiment. [Figure 24] FIG. 11 is a diagram illustrating an operation according to the fifth embodiment. [Figure 25] FIG. 2 is a diagram illustrating a detailed configuration example 1 of a RIS device according to an embodiment. [Figure 26] FIG. 10 is a diagram illustrating a second example of a detailed configuration of the RIS device according to the embodiment. [Figure 27] FIG. 10 is a diagram illustrating a detailed configuration example 3 of the RIS device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] It is believed that efficient coverage expansion can be achieved by operating the RIS device in conjunction with the operation of the base station. However, when the base station and the RIS device are connected by wire to communicate with each other, there are problems such as increased installation costs for the RIS device due to wiring work, and reduced flexibility in installation of the RIS device.

[0011] In the following embodiments, a communication control method, a wireless terminal, a base station, and a RIS device are described that enable efficient coverage expansion using a RIS device while suppressing increases in installation costs and reductions in installation flexibility for the RIS device.

[0012] [Embodiment]

[0013] (Configuration of a mobile communication system) First, the configuration of a mobile communication system according to one embodiment will be described. Fig. 1 is a diagram showing the configuration of a mobile communication system 1 according to one embodiment. The mobile communication system 1 conforms to the 3GPP standard 5th Generation System (5GS). In the following description, 5G / NR will be used as an example, but 4G / LTE may be applied at least in part to the mobile communication system 1, or a sixth generation (6G) system may be applied at least in part.

[0014] The mobile communication system 1 includes a radio terminal (UE: User Equipment) 100, a 5G radio access network (NG-RAN: Next Generation Radio Access Network) 10, and a 5G core network (5GC: 5G Core Network) 20.

[0015] The UE 100 is a mobile wireless communication device, such as a mobile phone terminal (including a smartphone), a tablet terminal, a laptop PC, a communication module (including a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0016] The NG-RAN 10 includes a base station (called a "gNB" in a 5G system) 200. The gNBs 200 are connected to each other via an Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with a UE 100 that has established a connection with its own cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, etc. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource that performs wireless communication with a UE 100. One cell belongs to one carrier frequency.

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

[0018] The 5GC20 includes an Access and Mobility Management Function (AMF) and a User Plane Function (UPF) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF controls data forwarding. The AMF and UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

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

[0020] As shown in Figure 2, the user plane radio interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0021] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the gNB 200 via a physical channel.

[0022] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of UE 100 and the MAC layer of gNB 200 via a transport channel. The MAC layer of 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 UE 100.

[0023] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 via logical channels.

[0024] The PDCP layer performs header compression / decompression and encryption / decryption.

[0025] The SDAP layer maps IP flows, which are the units for QoS control by the core network, to radio bearers, which are the units for QoS control by the AS (Access Stratum). Note that if the RAN is connected to the EPC, SDAP is not necessary.

[0026] 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).

[0027] As shown in FIG. 3, the protocol stack of the radio interface of the control plane has a Radio Resource Control (RRC) layer and a Non-Access Stratum (NAS) layer instead of the SDAP layer shown in FIG.

[0028] 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 radio connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no radio connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the radio connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in an RRC inactive state.

[0029] The NAS layer 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 300. Note that the UE 100 has an application layer and the like in addition to a radio interface protocol.

[0030] (RIS device application scenario) Next, application scenarios of the RIS device according to one embodiment will be described. Figures 4 to 6 are diagrams showing application scenarios of the RIS device according to one embodiment.

[0031] Compared to 4G / LTE, 5G / NR enables broadband transmission using higher frequency bands. Radio waves in high frequency bands, such as millimeter wave bands or terahertz wave bands, have high line-of-sight properties, which poses a challenge in reducing the coverage of the gNB 200. In Figures 4 to 6, it is assumed that there is an obstruction between the gNB 200 and UE 100A1 and UE 100A2, preventing UE 100A1 and UE 100A2 from communicating with the gNB 200 within line-of-sight. In such a case, the positions of UE 100A1 and UE 100A2 may become coverage holes.

[0032] Therefore, a RIS device 500 using metasurface technology is introduced into the mobile communication system 1. The RIS device 500 dynamically changes the propagation direction of radio waves (beams) incident from the gNB 200, for example, by reflection or refraction. This allows the coverage of the gNB 200 to be efficiently expanded. The RIS device 500 has features such as being reconfigurable, dynamic (dynamically controllable), and flexible (beam direction controllable). Note that while FIGS. 4 and 5 show an example in which the RIS device 500 is applied to downlink communications from the gNB 200 to the UE 100A1 and UE 100A2, the RIS device 500 can also be applied to uplink communications from the UE 100A1 and UE 100A2 to the gNB 200.

[0033] The RIS device 500 shown in FIG. 4 is a reflection-type RIS device 500. Such a RIS device 500 changes the propagation direction of an incident radio wave by reflecting the radio wave. Here, the reflection angle of the radio wave is variably settable. The RIS device 500 reflects the radio wave incident from the gNB 200 toward each of the UE 100A1 and the UE 100A2. The RIS device 500 may also reflect the radio wave incident from each of the UE 100A1 and the UE 100A2 toward the gNB 200. The RIS device 500 dynamically changes the reflection angle of the radio wave. For example, in the communication resource between the gNB 200 and the UE 100A1, the RIS device 500 reflects the radio wave incident from the gNB 200 toward the UE 100A1 and / or reflects the radio wave incident from the UE 100A1 toward the gNB 200. Here, the communication resource includes a time-direction resource and / or a frequency-direction resource. In the communication resources between gNB200 and UE100A2, RIS device 500 reflects radio waves incident from gNB200 toward UE100A2 and / or reflects radio waves incident from UE100A2 toward gNB200.

[0034] The RIS device 500 shown in FIG. 5 is a transparent RIS device 500. Such a RIS device 500 changes the propagation direction of an incident radio wave by refracting the radio wave. Here, the refraction angle of the radio wave is variably settable. The RIS device 500 refracts the radio wave incident from the gNB 200 toward each of the UE 100A1 and the UE 100A2. The RIS device 500 may also refract the radio wave incident from each of the UE 100A1 and the UE 100A2 toward the gNB 200. The RIS device 500 dynamically changes the refraction angle of the radio wave. For example, in the communication resource between the gNB 200 and the UE 100A1, the RIS device 500 refracts the radio wave incident from the gNB 200 toward the UE 100A1 and / or refracts the radio wave incident from the UE 100A1 toward the gNB 200. In the communication resources between gNB200 and UE100A2, RIS device 500 refracts radio waves incident from gNB200 toward UE100A2 and / or refracts radio waves incident from UE100A2 toward gNB200.

[0035] 6, one RIS device 500 may have both reflective and transmissive characteristics and be switchable between the reflective mode and the transmissive mode. For example, in a communication resource between the gNB 200 and the UE 100A1, the RIS device 500 reflects radio waves incident from the gNB 200 toward the UE 100A1 and / or reflects radio waves incident from the UE 100A1 toward the gNB 200. In a communication resource between the gNB 200 and the UE 100A2, the RIS device 500 refracts radio waves incident from the gNB 200 toward the UE 100A2 and / or refracts radio waves incident from the UE 100A2 toward the gNB 200.

[0036] In this way, by operating the RIS device 500 in conjunction with the operation of the gNB 200, it is possible to achieve efficient coverage expansion using the RIS device 500. However, when the gNB 200 and the RIS device 500 are connected by wire to communicate with each other, there are problems in that the installation costs of the RIS device 500 increase due to wiring work and the like, and the degree of freedom in installing the RIS device 500 decreases.

[0037] Therefore, as shown in FIG. 7 , a new UE (hereinafter referred to as “RIS-UE”) for controlling the RIS device 500 is introduced. The RIS-UE 100B is an example of a RIS radio terminal. The RIS-UE 100B controls the RIS device 500 in cooperation with the gNB 200 by establishing a wireless connection with the gNB 200 and performing wireless communication with the gNB 200. This makes it possible to achieve efficient coverage expansion using the RIS device 500 while suppressing increases in installation costs and reductions in installation flexibility for the RIS device 500. The RIS-UE 100B controls the RIS device 500 in accordance with a RIS control setting from the gNB 200. The RIS-UE 100B may autonomously control the RIS device 500 in accordance with a preset RIS control setting even if the RIS control setting is not set by the gNB 200. Note that the control setting (e.g., the RIS control setting) is also control information (e.g., the RIS control information).

[0038] The RIS-UE 100B may be configured separately from the RIS device 500. For example, the RIS-UE 100B may be located near the RIS device 500 and electrically connected to the RIS device 500. The RIS-UE 100B may be connected to the RIS device 500 by wire or wirelessly. Alternatively, the RIS-UE 100B may be configured integrally with the RIS device 500. The RIS-UE 100B and the RIS device 500 may be fixedly installed, for example, on a wall or window. The RIS-UE 100B and the RIS device 500 may be mobile, installed, for example, in a vehicle. Furthermore, one RIS-UE 100B may control multiple RIS devices 500.

[0039] (RIS-UE and RIS device configuration) Next, a description will be given of the configuration of the RIS-UE 100B (RIS wireless terminal) and the RIS device 500 according to one embodiment. Fig. 8 is a diagram showing the configuration of the RIS-UE 100B and the RIS device 500 according to one embodiment.

[0040] As shown in FIG. 8, RIS-UE 100B includes receiving unit 110, transmitting unit 120, control unit 130, and interface 140.

[0041] The receiving unit 110 performs various receptions under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts radio waves (radio signals) received by the antenna into baseband signals (received signals) and outputs them to the control unit 130. The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signals (transmitted signals) output by the control unit 130 into radio signals and transmits them from the antenna.

[0042] The control unit 130 performs various controls in the RIS-UE 100B. 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 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.

[0043] Interface 140 is electrically connected to RIS device 500. Control unit 130 controls RIS device 500 via interface 140. Note that if RIS-UE 100B and RIS device 500 are configured integrally, RIS-UE 100B does not need to have interface 140.

[0044] The RIS device 500 includes a RIS 510 and a RIS control unit 520. The RIS 510 is a metasurface made of metamaterial. For example, the RIS 510 is configured by arranging extremely small structures relative to the wavelength of radio waves in an array. By varying the shape of the structures depending on their placement, it is possible to arbitrarily design the direction and beam shape of the reflected waves. The RIS 510 may be a transparent dynamic metasurface. The RIS 510 may be configured by overlaying a transparent glass substrate on a transparent metasurface substrate on which a large number of small structures are regularly arranged. By minutely moving the overlaid glass substrate, it may be possible to dynamically control three patterns: a mode that transmits incident radio waves, a mode that transmits and reflects some of the radio waves, and a mode that reflects all of the radio waves.

[0045] The RIS control unit 520 controls the RIS 510 in response to control signals from the control unit 130 of the RIS-UE 100B. The RIS control unit 520 may include at least one processor and at least one actuator. The processor decodes the control signal from the control unit 130 of the RIS-UE 100B and drives the actuator in response to the control signal. Note that when the RIS-UE 100B and the RIS device 500 are configured integrally, the control unit 130 of the RIS-UE 100B and the RIS control unit 520 of the RIS device 500 may also be configured integrally.

[0046] In one embodiment, the receiver 110 of the RIS-UE 100B receives one or more RIS control settings used to control the RIS device 500 from the gNB 200 via wireless communication. The controller 130 of the RIS-UE 100B controls the RIS device 500 based on the one or more RIS control settings. The RIS control settings are an example of downlink signaling from the gNB 200 to the RIS-UE 100B. This enables the gNB 200 to control the RIS device 500 via the RIS-UE 100B.

[0047] In one embodiment, the control unit 130 of the RIS-UE 100B controls the RIS device 500. The control unit 130 of the RIS-UE 100B acquires RIS device information indicating at least one of the capabilities of the RIS device 500 and the control status of the RIS device 500 from the RIS device 500 (RIS control unit 520). Then, the transmission unit 120 of the RIS-UE 100B transmits the acquired RIS device information to the gNB 200 via wireless communication. The RIS device information is an example of uplink signaling from the RIS-UE 100B to the gNB 200. This allows the gNB 200 to grasp the capabilities and control status of the RIS device 500.

[0048] (Base station configuration) Next, a configuration of the gNB 200 (base station) according to an embodiment will be described. Fig. 9 is a diagram showing the configuration of the gNB 200 according to an embodiment.

[0049] As shown in FIG. 9, the gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240.

[0050] 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.

[0051] The control unit 230 performs various controls in the gNB 200. 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.

[0052] The backhaul communication unit 240 is connected to neighboring base stations via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF 300 via a base station-core network interface. Note that the gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally divided), and both units may be connected via an F1 interface.

[0053] In one embodiment, the transmitter 210 of the gNB 200 transmits, via wireless communication, to the RIS-UE 100B that controls the RIS device 500, one or more RIS control settings used to control the RIS device 500. The RIS control settings are an example of downlink signaling from the gNB 200 to the RIS-UE 100B. This enables the gNB 200 to control the RIS device 500 via the RIS-UE 100B.

[0054] In one embodiment, the receiver 220 of the gNB 200 receives, via wireless communication, RIS device information indicating at least one of the capabilities of the RIS device 500 and the control status of the RIS device 500 from the RIS-UE 100B that controls the RIS device 500. The RIS device information is an example of uplink signaling from the RIS-UE 100B to the gNB 200. This enables the gNB 200 to grasp the capabilities and control status of the RIS device 500.

[0055] (Mobile communication system operation) Next, the operation of the mobile communication system 1 according to one embodiment will be described.

[0056] (1) Downlink signaling FIG. 10 is a diagram showing downlink signaling from gNB200 to RIS-UE100B according to one embodiment.

[0057] The gNB 200 (transmitter 210) transmits downlink signaling to the RIS-UE 100B. The downlink signaling may be an RRC message, which is signaling of the RRC layer, a MAC CE (Control Element), which is signaling of the MAC layer, or downlink control information (DCI), which is signaling of the PHY layer. The downlink signaling may be UE-specific signaling or broadcast signaling. The downlink signaling may be a fronthaul message (e.g., an F1-AP message).

[0058] For example, as shown in FIG. 10, the gNB 200 (transmitter 210) transmits downlink signaling including a RIS control setting used to control the RIS device 500 to the RIS-UE 100B that has established a wireless connection with the gNB 200 (step S1). The gNB 200 (transmitter 210) may include the RIS control setting in an RRC Reconfiguration message, which is a type of RRC message individual to a UE, and transmit this to the RIS-UE 100B. The downlink signaling may be a message of a layer higher than the RRC layer (for example, a RIS application). The downlink signaling may be a message of a layer higher than the RRC layer encapsulated in a message of a layer lower than the RRC layer and transmitted.

[0059] The RIS-UE 100B (transmitting unit 120) may transmit, via uplink, a response message in response to the downlink signaling from the gNB 200. The response message may be transmitted in response to the RIS device 500 completing the configuration specified in the downlink signaling or receiving the configuration.

[0060] As shown in FIG. 11, the RIS control setting may include frequency setting information that sets the center frequency of radio waves (e.g., component carriers) targeted by the RIS device 500. When the RIS control setting received from the gNB 200 includes frequency setting information, the RIS-UE 100B (control unit 130) controls the RIS device 500 to operate (e.g., reflect, transmit (refract), or block) on radio waves having the center frequency indicated by the frequency setting information. The RIS control setting may include multiple pieces of frequency setting information that set different center frequencies. By including frequency setting information in the RIS control setting, the gNB 200 can specify, via the RIS-UE 100B, the center frequency of radio waves that the RIS device 500 should target.

[0061] The RIS control setting may include mode setting information that sets the operation mode of the RIS device 500. The mode setting information may be associated with frequency setting information (center frequency). The operation mode may be any one of a reflection mode that reflects radio waves, a refraction mode that refracts radio waves, a transmission mode that transmits radio waves, and a blocking mode that blocks radio waves. When the RIS control setting received from the gNB 200 includes mode setting information, the RIS-UE 100B (control unit 130) controls the RIS device 500 to operate in the operation mode indicated by the mode setting information. When the RIS control setting includes mode setting information, the gNB 200 can specify the operation mode of the RIS device 500 via the RIS-UE 100B.

[0062] The RIS control setting may include direction setting information that sets the propagation direction of the radio waves after the change by the RIS device 500. The direction setting information may be associated with frequency setting information (center frequency). The direction setting information may be information that sets the reflection angle at the RIS device 500, or may be information that sets the refraction angle at the RIS device 500. By including the direction setting information in the RIS control setting, the gNB200 can specify the propagation direction of the radio waves after the change by the RIS device 500 via the RIS-UE100B.

[0063] As shown in FIG. 12, when the RIS-UE 100B controls multiple RIS devices 500, the gNB 200 (transmitter 210) may transmit a RIS control setting to the RIS-UE 100B for each RIS device 500. In this case, the RIS control setting may include an identifier (RIS device identifier) ​​of the corresponding RIS device 500. The RIS-UE 100B (controller 130), which controls multiple RIS devices 500, determines the RIS device 500 to which the RIS control setting applies based on the RIS device identifier included in the RIS control setting received from the gNB 200. Note that the RIS device identifier may be transmitted from the RIS-UE 100B to the gNB 200 along with the RIS control setting, even when the RIS-UE 100B controls only one RIS device 500.

[0064] In this way, the RIS-UE 100B (control unit 130) controls the RIS device 500 based on the RIS control settings from the gNB 200. This allows the gNB 200 to control the RIS device 500 via the RIS-UE 100B.

[0065] (2) Uplink signaling FIG. 13 is a diagram showing uplink signaling from RIS-UE 100B to gNB 200 according to one embodiment.

[0066] The RIS-UE 100B (transmitter 210) transmits uplink signaling to the gNB 200. The uplink signaling may be an RRC message, which is signaling of the RRC layer, a MAC CE, which is signaling of the MAC layer, or uplink control information (UCI), which is signaling of the PHY layer. The uplink signaling may be a fronthaul message (e.g., an F1-AP message). The uplink signaling may be a message of a layer higher than the RRC layer (e.g., a RIS application). The uplink signaling may be a message of a layer higher than the RRC layer encapsulated in a message of a layer lower than the RRC layer and transmitted. Note that the gNB 200 (transmitter 210) may transmit a response message in response to the uplink signaling from the RIS-UE 100B on the downlink, and the RIS-UE 100B (receiver 110) may receive the response message.

[0067] For example, the RIS-UE 100B (transmitter 120) that has established a wireless connection with the gNB 200 transmits RIS device information indicating at least one of the capabilities of the RIS device 500 and the control state of the RIS device 500 to the gNB 200 via wireless communication (step S2). Specifically, the RIS device information includes at least one of RIS device capability information indicating the capabilities of the RIS device 500 and control state information indicating the control state of the RIS device 500. The RIS-UE 100B (transmitter 120) may include the RIS device information in a UE Capability message or a UE Assistant Information message, which are types of RRC messages, and transmit the message to the gNB 200. The RIS-UE 100B (transmitter 120) may transmit the RIS device information (RIS device capability information and / or control state information) to the gNB 200 in response to a request or inquiry from the gNB 200. The RIS-UE 100B (transmitter 120) may periodically transmit the RIS device information (particularly, control state information) to the gNB 200 in accordance with a setting from the gNB 200. This transmission period may be set from the gNB200 to the RIS-UE100B.

[0068] 14, the RIS device capability information may include supported frequency information indicating frequencies supported by the RIS device 500. The supported frequency information may be a numerical value or an index indicating a range of frequencies supported by the RIS device 500. When the RIS device capability information received from the RIS-UE 100B includes supported frequency information, the gNB 200 (control unit 230) can determine the frequencies supported by the RIS device 500 based on the supported frequency information. Then, the gNB 200 (control unit 230) may set the center frequency of the radio waves targeted by the RIS device 500 within the range of frequencies supported by the RIS device 500.

[0069] The RIS device capability information may include mode capability information regarding operation modes that the RIS device 500 can support or switching between operation modes. The operation mode may be at least one of a reflection mode that reflects radio waves, a refraction mode that refracts radio waves, a transmission mode that transmits radio waves, and a blocking mode that blocks radio waves. The mode capability information may be information indicating which of these operation modes the RIS device 500 can support. The mode capability information may be information indicating which of these operation modes mode switching is possible between. When the RIS device capability information received from the RIS-UE 100B includes mode capability information, the gNB 200 (control unit 230) can determine the operation modes and mode switching supported by the RIS device 500 based on the mode capability information. The gNB 200 (control unit 230) may then set the operation mode of the RIS device 500 within the range of the determined operation modes and mode switching.

[0070] The RIS device capability information may include angle capability information regarding the angle change of the propagation direction that the RIS device 500 can handle. The angle capability information may be, for example, information indicating a variable range of the reflection angle or refraction angle based on the horizontal or vertical direction (e.g., refraction can be controlled from 30° to 90°), or information indicating an absolute angle. The angle capability information may be information indicating an angle change per variable step (e.g., 5° / step horizontally, 10° / step vertically), or information indicating the number of variable steps (e.g., 10 steps horizontally, 20 steps vertically). When the RIS device capability information received from the RIS-UE 100B includes angle capability information, the gNB 200 (control unit 230) can determine the angle change that the RIS device 500 can handle based on the angle capability information. The gNB 200 (control unit 230) may then set the propagation direction of the radio wave after the change by the RIS device 500 within the determined range of angle change.

[0071] The RIS device capability information may include control delay information indicating a control delay time in the RIS device 500. For example, the control delay information is information indicating a delay time (e.g., 1 ms, 10 ms, etc.) from the timing when the UE 100 receives the RIS control setting or the timing when the UE 100 transmits a setting completion notice for the RIS control setting to the gNB 200 until the control (change of the operation mode or change of the reflection angle or refraction angle) according to the RIS control setting is completed. When the RIS device capability information received from the RIS-UE 100B includes control delay information, the gNB 200 (control unit 230) can grasp the control delay time in the RIS device 500 based on the control delay information.

[0072] The RIS device capability information may include attenuation characteristic information indicating radio wave attenuation characteristics of the RIS device 500. The attenuation characteristic information includes at least one of information indicating transmission attenuation in dB (decibels) and information indicating return attenuation in dB (decibels). When the RIS device capability information received from the RIS-UE 100B includes attenuation characteristic information, the gNB 200 (control unit 230) can determine the radio wave attenuation characteristics of the RIS device 500 based on the attenuation characteristic information. The RIS device capability information may include information indicating the installation location of the RIS 510. The information indicating the installation location may include one or more of latitude, longitude, and altitude. The information indicating the installation location may include information indicating the distance from the gNB 200 and / or the installation angle of the RIS 510. The installation angle may be a relative angle to the gNB 200, or may be a relative angle based on, for example, north, vertical, or horizontal.

[0073] As shown in FIG. 15, when RIS-UE 100B controls multiple RIS devices 500, RIS-UE 100B (transmitter 120) may transmit RIS device capability information for each RIS device 500 to gNB 200. In this case, the RIS device capability information may include an identifier (RIS device identifier) ​​of the corresponding RIS device 500. Furthermore, when RIS-UE 100B controls multiple RIS devices 500, RIS-UE 100B (transmitter 120) may transmit information indicating at least one of the identifiers of the multiple RIS devices 500 and the number of the multiple RIS devices 500. Note that the RIS device identifier may be transmitted from RIS-UE 100B to gNB 200 together with the RIS device capability information, even when RIS-UE 100B controls only one RIS device 500.

[0074] 16, the control state information may include frequency state information indicating the center frequency of the radio waves targeted by the RIS device 500. The frequency state information may be information indicating the latest (current) center frequency of the radio waves targeted by the RIS device 500 at the time of transmitting the control state information. When the control state information received from the RIS-UE 100B includes frequency state information, the gNB 200 (control unit 230) can determine the center frequency of the radio waves targeted by the RIS device 500 based on the frequency state information.

[0075] The control state information may include mode state information indicating the operation mode of the RIS device 500. The mode state information may be information indicating the latest (current) operation mode of the RIS device 500 at the time of transmitting the control state information. The operation mode may be any one of a reflection mode that reflects radio waves, a refraction mode that refracts radio waves, a transmission mode that transmits radio waves, and a blocking mode that blocks radio waves. When the control state information received from the RIS-UE 100B includes mode state information, the gNB 200 (control unit 230) can determine the operation mode of the RIS device 500 based on the mode state information.

[0076] The control state information may include directional state information indicating the propagation direction of the radio waves after the change by the RIS device 500. The directional state information may be information indicating the reflection angle or refraction angle of the radio waves at the RIS device 500. The directional state information may be information indicating the latest (current) propagation direction of the radio waves of the RIS device 500 at the time of transmitting the control state information. When the control state information received from the RIS-UE 100B includes directional state information, the gNB 200 (control unit 230) can determine the propagation direction of the radio waves after the change by the RIS device 500 based on the directional state information.

[0077] 17, when RIS-UE 100B controls multiple RIS devices 500, RIS-UE 100B (transmitter 120) may transmit control status information to gNB 200 for each RIS device 500. In this case, the control status information may include an identifier (RIS device identifier) ​​of the corresponding RIS device 500. Note that the RIS device identifier may be transmitted from RIS-UE 100B to gNB 200 together with the control status information, even when RIS-UE 100B controls only one RIS device 500.

[0078] In this way, the RIS-UE 100B (control unit 130) controls the RIS device 500 based on the RIS control settings from the gNB 200. This allows the gNB 200 to control the RIS device 500 via the RIS-UE 100B.

[0079] In this way, the RIS-UE 100B (transmitter 120) transmits, via wireless communication, to the gNB 200, RIS device information indicating at least one of the capabilities of the RIS device 500 and the control status of the RIS device 500. This allows the gNB 200 to grasp the capabilities and control status of the RIS device 500.

[0080] (3) Operation related to measurements using RIS-UE 18 is a diagram showing the operation related to measurements by the RIS-UE 100B according to one embodiment. The RIS-UE 100B measures the radio conditions. Here, the RIS-UE 100B is configured integrally with the RIS device 500 or is located near the RIS device 500. Therefore, the radio conditions in the RIS-UE 100B can be treated as equivalent to the radio conditions in the RIS device 500.

[0081] As shown in FIG. 18, in step S11, the gNB 200 (transmitter 210) transmits a configuration related to measurement (measurement configuration) to the RIS-UE 100B that has established a radio connection with the gNB 200. The measurement configuration configures the RIS-UE 100B to measure at least one of radio waves incident on the RIS device 500 from the gNB 200 and radio waves incident on the RIS device 500 from the UE 100 (for example, the above-mentioned UE 100A) and report the measurement results. The measurement configuration may include information for setting at least one of a frequency to be measured, a signal to be measured (for example, DM-RS or CSI-RS, which are downlink reference signals, and / or SRS, which is an uplink reference signal), a resource to be measured (for example, a subframe, a resource element, and / or a signal sequence), and a report type. The report type may be a periodic report or an event-triggered report.

[0082] In step S12, the RIS-UE 100B (control unit 130) measures the radio state (radio measurement) based on the measurement configuration received from the gNB 200 in step S11. The RIS device 500 (control unit 130) performs radio measurement (i.e., downlink measurement) on radio waves from the gNB 200 that enter the RIS device 500. The RIS device 500 (control unit 130) may also perform radio measurement (i.e., uplink measurement) on radio waves from the UE 100 that enter the RIS device 500.

[0083] The measurement by the RIS-UE 100B may be a radio resource management (RRM) measurement mainly performed in the RRC layer, or a channel state information (CSI) measurement mainly performed in the PHY layer. The measurement result obtained by the RRM measurement may be, for example, at least one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), and a received signal strength indicator (RSSI). The measurement result obtained by the CSI measurement may be, for example, at least one of a channel quality indicator (CQI), a precoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), a strong layer indicator (SLI), a rank indicator (RI), and an L1-RSRP.

[0084] In step S13, the RIS-UE 100B (transmitting unit 120) transmits a report including the measurement result obtained in step S12 to the gNB 200. The measurement result is at least one of an RRM measurement result and a CSI measurement result.

[0085] In step S14, the gNB200 (control unit 230) controls the transmission of radio waves (e.g., the transmission directivity of the beam) based on the report of the measurement results received from the RIS-UE100B in step S13. For example, the gNB200 (control unit 230) controls the transmission directivity so that the beam is directed toward the RIS device 500. The gNB200 (control unit 230) may reconfigure the RIS device 500 via the RIS-UE200B.

[0086] In this way, the gNB200 (control unit 230) can perform appropriate beamforming using the measurement results by the RIS-UE100B by treating the radio conditions in the RIS-UE100B as equivalent to the radio conditions in the RIS device 500.

[0087] [Example] Next, based on the above-described embodiment, first to fifth examples will be described. These examples are not limited to being implemented independently, but two or more examples may be combined and implemented. Also, in the operation flow of each of the following examples, it is not necessary to execute all steps, and only some of the steps may be executed.

[0088] (1) First Example FIG. 19 is a diagram showing the operation according to the first embodiment.

[0089] As shown in FIG. 19, in step S101, the RIS-UE 100B is in the RRC idle state or the RRC inactive state.

[0090] In step S102, the gNB200 (transmitter 210) broadcasts RIS support information indicating that the gNB200 supports the RIS-UE100B. For example, the gNB200 (transmitter 210) broadcasts a system information block (SIB) including the RIS support information. Alternatively, the gNB200 (transmitter 210) may broadcast RIS non-support information indicating that the gNB200 does not support the RIS-UE100B.

[0091] A RIS-UE 100B (control unit 130) that has not established a wireless connection with a gNB 200 may determine, upon receiving RIS support information from the gNB 200, that access to the gNB 200 is permitted, and may perform an access operation to establish a wireless connection with the gNB 200. The RIS-UE 100B (control unit 130) may perform cell reselection by regarding the gNB 200 (cell) to which access is permitted as having the highest priority.

[0092] On the other hand, if the gNB 200 does not broadcast RIS support information (or broadcasts RIS non-support information), the RIS-UE 100B (control unit 130) that has not established a wireless connection with the gNB 200 may determine that it is unable to access (establish a connection with) the gNB 200. This allows the RIS-UE 100B to establish a wireless connection only with gNBs 200 that can handle the RIS-UE 100B.

[0093] Note that if the gNB 200 is congested, the gNB 200 may broadcast access restriction information that restricts access from the UE 100. However, unlike a normal UE 100, the RIS-UE 100B can be considered a network-side entity. Therefore, the RIS-UE 100B may ignore the access restriction information from the gNB 200. For example, when the RIS-UE 100B (control unit 130) receives RIS support information from the gNB 200, it may perform an operation to establish a wireless connection with the gNB 200 even if the gNB 200 broadcasts access restriction information. For example, the RIS-UE 100B (control unit 130) may not execute (or may ignore) UAC (Unified Access Control). Alternatively, a special value indicating access by a RIS-UE may be used as either or both of the AC / AI (Access Category / Access Identity) used in the UAC.

[0094] In step S103, the RIS-UE 100B (control unit 130) starts a random access procedure for the gNB 200. In the random access procedure, the RIS-UE 100B (transmitting unit 120) transmits a random access preamble (Msg1) and an RRC message (Msg3) to the gNB 200. Also in the random access procedure, the RIS-UE 100B (receiving unit 110) receives a random access response (Msg2) and an RRC message (Msg4) from the gNB 200.

[0095] In step S104, when establishing a wireless connection with the gNB 200, the RIS-UE 100B (transmitting unit 120) may transmit RIS-UE information indicating that its own UE is a RIS-UE to the gNB 200. For example, during a random access procedure with the gNB 200, the RIS-UE 100B (transmitting unit 120) includes the RIS-UE information in a message for the random access procedure (e.g., Msg1, Msg3, Msg5) and transmits the message to the gNB 200. Based on the RIS-UE information received from the RIS-UE 100B, the gNB 200 (control unit 230) recognizes that the accessing UE 100 is the RIS-UE 100B, and can, for example, exclude the RIS-UE 100B from the access restriction targets (i.e., accept the access).

[0096] In step S105, the RIS-UE 100B transitions from the RRC idle state or the RRC inactive state to the RRC connected state.

[0097] In step S106, the gNB 200 (transmitting unit 120) transmits a capability inquiry message to the RIS-UE 100 B to inquire about the capabilities of the RIS-UE 100 B. The RIS-UE 100 B (receiving unit 110) receives the capability inquiry message.

[0098] In step S107, the RIS-UE 100B (transmitter 120) transmits a capability information message including the above-mentioned RIS device capability information to the gNB 200. The gNB 200 (receiver 220) receives the capability information message. The gNB 200 (controller 230) determines the capabilities of the RIS device 500 based on the received capability information message.

[0099] In step S108, the gNB 200 (transmitter 210) transmits to the RIS-UE 100B an RRC message (measurement configuration message) including measurement configuration information for configuring measurement by the RIS-UE 100B. The RIS-UE 100B (receiver 110) receives the measurement configuration message. The RIS-UE 100B (controller 130) performs radio measurement based on the measurement configuration message.

[0100] In step S109, the RIS-UE 100B (transmitter 120) transmits a report (measurement report) including radio measurement results to the gNB 200. The gNB 200 (controller 230) may perform beamforming so that the beam is directed toward the RIS-UE 100B (RIS device 500) based on the measurement report received from the RIS-UE 100B. The gNB 200 (controller 230) may determine the RIS control settings to be set for the RIS-UE 100B based on the measurement report received from the RIS-UE 100B.

[0101] In step S110, the gNB 200 (transmitter 120) transmits to the RIS-UE 100B a RIS control setting used to control the RIS device 500. The gNB 200 (transmitter 120) may transmit to the RIS-UE 100B an RRC Reconfiguration message including the RIS control setting. The RIS-UE 100B (receiver 110) receives the RIS control setting.

[0102] In step S111, the RIS-UE 100B (control unit 130) controls the RIS device 500 based on the RIS control setting received from the gNB 200. The RIS-UE 100B (control unit 130) may control the RIS device 500 by notifying the RIS device 500 (RIS control unit 520) of the RIS control setting received from the gNB 200.

[0103] In step S112, when the control (setting change) of the RIS device 500 is completed, the RIS-UE 100B (transmitter 120) transmits a control setting completion message (e.g., an RRC Reconfiguration Complete message) to the gNB 200. Here, the RIS-UE 100B (controller 130) may determine the control completion based on a notification (feedback) from the RIS device 500 (RIS control unit 520). The gNB 200 (receiver 220) receives the control setting completion message.

[0104] (2) Second Example In the above-described embodiment and the first example, it was mainly assumed that the RIS device 500 was controlled semi-statically. In the second example, it is assumed that the RIS device 500 can be controlled dynamically. Fig. 20 is a diagram showing the operation according to the second example.

[0105] As shown in FIG. 20 , in step S201, the gNB 200 (transmitter 120) transmits one or more RIS control configurations and control timing information indicating the timing at which each of the one or more RIS control configurations is applied to the RIS-UE 100B. For example, the gNB 200 (transmitter 120) transmits an RRC message (e.g., an RRC Reconfiguration message) including the RIS control configuration and the control timing information to the RIS-UE 100B. The RIS-UE 100B (receiver 110) receives the RIS control configuration and the control timing information. Note that step S201 corresponds to step S110 in the first embodiment described above.

[0106] In step S202, RIS-UE 100B (control unit 130) controls RIS device 500 based on the RIS control setting and control timing information received in step S201. Specifically, RIS-UE 100B (control unit 130) controls RIS device 500 in accordance with the RIS control setting associated with the control timing information at the timing indicated by the control timing information.

[0107] FIG. 21 is a diagram showing an example of the configuration of RIS control setting and control timing information according to the second embodiment.

[0108] As shown in Figure 21, RIS control setting #1 and RIS control setting #2 are each associated with different control timing information. For example, the control timing information associated with RIS control setting #1 indicates that RIS control setting #1 is applied at frame numbers #1, #3, #5, etc. The control timing information associated with RIS control setting #2 indicates that RIS control setting #2 is applied at frame numbers #2, #4, #6, etc. The RIS-UE 100B (control unit 130) can ascertain the current frame number based on the frame number broadcast by the gNB 200 (for example, the frame number in the master information block, etc.).

[0109] Here, the frame number may be a hyper system frame number (H-SFN), a system frame number (SFN), or a subframe number. The control timing information may include a slot number and / or an OFDM symbol number instead of or in addition to the frame number, or may include absolute time (e.g., GPS time). In this way, multiple RIS control settings are applied to the control of the RIS device 500 at different timings. The control timing information includes information indicating the application timing of each of the multiple RIS control settings.

[0110] FIG. 21 shows an example in which the timing for applying the RIS control setting is specified by a frame number or the like. However, the control timing information may be configured in a bitmap format consisting of bits each associated with a frame number. For example, the RIS-UE 100B (control unit 130) applies the RIS control setting at a frame number that is "1" in the bitmap, and does not apply the RIS control setting at a radio frame that is 0. The control timing information may further include the start frame number to which the bitmap is applied.

[0111] According to the second embodiment, the RIS device 500 can be dynamically controlled by transmitting control timing information indicating the timing at which the RIS control setting is applied from the gNB 200 to the RIS-UE 100B.

[0112] (3) Third Example In the third embodiment, an example will be described in which synchronization signal block (SS / PBCH Block: SSB) transmission is linked with the control of the RIS device 500. The SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a PBCH (Physical Broadcast Channel), and a demodulation reference signal (DMRS). For example, the SSB may be composed of four consecutive OFDM symbols in the time domain. The SSB may also be composed of 240 consecutive subcarriers (20 resource blocks) in the frequency domain. The PBCH is a physical channel that carries a master information block (MIB). Figure 22 is a diagram showing the operation according to the third embodiment.

[0113] In SSB transmission, the gNB 200 performs beam sweeping by changing the weighting (directivity) for each SSB. When a RIS device 500, specifically a RIS (metasurface) 510, is present in the propagation path between the gNB 200 and the UE 100, the communication quality changes depending on the control of the RIS device 500. Therefore, by linking the beam sweeping with the control of the RIS device 500, it is possible to optimize SSB transmissions that involve the RIS device 500.

[0114] As shown in Figure 22, the gNB 200 (transmitter 210) transmits multiple SSBs at different times and using different beams. Figure 22 shows an example in which the gNB 200 (transmitter 210) transmits a total of seven SSBs, SSB1 to SSB7. Here, the gNB 200 (transmitter 210) transmits a set of SSB3 to SSB5 (hereinafter referred to as the "SSB set") with the same weighting (i.e., the same beam characteristics). Although an example in which the number of SSBs constituting the SSB set is three is shown, the number of SSBs constituting the SSB set may be two, or may be four or more.

[0115] The gNB200 (transmitting unit 210) may transmit information regarding each SSB included in the SSB set (e.g., SSB identifier and / or transmission timing information) to the RIS-UE100B, for example, by an RRC message. The gNB200 (transmitting unit 210) may also transmit a RIS control configuration to the RIS-UE100B in association with information regarding each SSB included in the SSB set. That is, the gNB200 (transmitting unit 210) may transmit a RIS control configuration to the RIS-UE100B for each SSB included in the SSB set. The gNB200 (transmitting unit 210) may specify different application timings for each RIS control configuration using the above-mentioned control timing information. The control timing information for the SSB may be the same information element as the above-mentioned control timing information, or may be a different information element from the above-mentioned control timing information.

[0116] The RIS-UE 100B controls the RIS device 500, specifically the RIS (metasurface) 510, by applying different RIS control settings to each SSB included in the SSB set. Figure 22 shows an example in which SSB3 included in the SSB set is reflected or refracted at a certain angle, SSB4 included in the SSB set is transmitted, and SSB5 included in the SSB set is reflected or refracted at a certain angle. Here, the propagation direction (reflection angle or refraction angle) of each SSB after the change by the RIS device 500 is linked to the original propagation direction of each SSB transmitted by the gNB 200.

[0117] As described above, in the third embodiment, the gNB 200 transmits multiple SSBs (SSB set) with different transmission timings toward the RIS device 500. A RIS control setting is associated with the multiple SSBs. Specifically, the gNB 200 transmits the multiple SSBs toward the RIS device 500 with the same beam characteristics. The RIS-UE 100B controls the propagation direction of each of the multiple SSBs based on the RIS control setting. This makes it possible to vary the propagation direction (reflection angle or refraction angle) for each SSB included in the SSB set.

[0118] In the third embodiment, an example was described in which the RIS-UE 100B controls the RIS device 500 in accordance with the RIS control setting from the gNB 200. However, the RIS-UE 100B may autonomously control the RIS device 500 in accordance with a preset RIS control setting even if the RIS control setting is not set from the gNB 200. In this case, the RIS-UE 100B may notify the gNB 200 of the preset RIS control setting as the above-mentioned control state information. Details of such an operation will be described in the fourth embodiment described below.

[0119] (4) Fourth Example In the fourth embodiment, an example will be described in which the RIS-UE 100B autonomously controls the RIS device 500 and notifies the gNB 200 of the current control state. The RIS-UE 100B may autonomously control the RIS device 500 based on auxiliary information from the gNB 200. Figure 23 is a diagram showing the operation according to the fourth embodiment.

[0120] As shown in FIG. 23, in step S301, RIS-UE 100B (control unit 130) autonomously controls RIS device 500.

[0121] In step S302, the gNB200 (transmitter 210) transmits to the RIS-UE100B a control state inquiry that inquires of the UE100 about the above-mentioned control state information, or a control state transmission setting that sets the UE100 to transmit the above-mentioned control state information. The gNB200 (transmitter 210) may transmit to the RIS-UE100B an RRC message including the control state inquiry or the control state transmission setting. The control state transmission setting may include information that sets a cycle at which the control state information is transmitted from the RIS-UE100B to the gNB200, or information that sets a trigger event for transmitting the control state information from the RIS-UE100B to the gNB200 (for example, an event that the radio state (RSRP, etc.) of the RIS-UE100B exceeds a threshold, or an event that the radio state of the RIS-UE100B falls below a threshold).

[0122] In step S303, the RIS-UE 100B (transmitting unit 120) transmits control state information to the gNB 200 based on the control state inquiry or control state transmission setting received from the gNB 200. The gNB 200 (control unit 130) determines the current control state of the RIS-UE 100B (RIS device 500) based on the control state information received from the gNB 200.

[0123] According to the fourth embodiment, even when the RIS-UE 100B autonomously controls the RIS device 500, the gNB 200 can grasp the current control status.

[0124] (5) Fifth Example In the fifth embodiment, an example will be described in which the RIS-UE 100B performs handover between the gNBs 200. Fig. 24 is a diagram showing the operation according to the fifth embodiment.

[0125] 24, in step S401, the RIS-UE 100B (control unit 130) transmits a measurement report to the gNB 200A. The gNB 200A (control unit 230) determines handover of the RIS-UE 100B to the gNB 200B based on the measurement report received from the RIS-UE 100B.

[0126] In step S402, the gNB200A (backhaul communication unit 240) transmits a handover request message to the gNB200B requesting a handover of the RIS-UE100B. Here, the gNB200A (backhaul communication unit 240) may include the RIS control setting that the gNB200A has set for the RIS-UE100B in the handover request message and transmit it to the gNB200B. The gNB200A (backhaul communication unit 240) may include RIS device information that the gNB200A has received from the RIS-UE100B in the handover request message and transmit it to the gNB200B.

[0127] The gNB 200B (control unit 230) determines whether to approve the handover of the RIS-UE 100B based on the handover request received from the gNB 200A. Here, the description will proceed assuming that it has been determined that the handover is approved.

[0128] In step S403, the gNB 200B (backhaul communication unit 240) transmits a handover acknowledgement message to the gNB 200A. The gNB 200B (backhaul communication unit 240) may include the RIS control setting to be set in the RIS-UE 100B after the handover in the handover acknowledgement message and transmit the message to the gNB 200A.

[0129] In step S404, the gNB 200A (transmitting unit 210) transmits a handover command to the RIS-UE 100B instructing a handover to the gNB 200B. The gNB 200A (transmitting unit 210) may include the RIS control setting received from the gNB 200B in the handover command and transmit it to the RIS-UE 100B.

[0130] In step S405, in response to receiving the handover command, the RIS-UE 100B (control unit 130) establishes a wireless connection with the gNB 200B by performing a random access procedure with the gNB 200B. After the handover, the RIS-UE 100B (control unit 130) may control the RIS device 500 based on the RIS control setting included in the handover command.

[0131] According to the fifth embodiment, even when the RIS-UE 100B performs a handover between gNBs 200, the handover of the RIS-UE 100B can be appropriately controlled.

[0132] [Detailed configuration example of RIS device] Next, a detailed configuration example of the RIS device 500 according to the embodiment will be described. Fig. 25 is a diagram showing a detailed configuration example 1 of the RIS device 500 according to the embodiment.

[0133] As described above, the RIS device 500 according to this configuration example includes a metasurface (RIS) 510 configured to change the propagation direction of incident radio waves, and a RIS control unit 520 that controls the metasurface 510. The RIS control unit 520 controls the metasurface 510 in response to an instruction (control signal) from the RIS-UE 100B. The metasurface 510 has a plate-like shape. Specifically, the metasurface 510 has a main surface 510a onto which radio waves are incident and a back surface 510b opposite the main surface 510a. The main surface 510a may be a reflective surface that reflects the incident radio waves.

[0134] The RIS-UE 100B has one or more UE antennas (terminal antennas) 101 for wireless communication with the gNB 200. FIG. 25 shows an example in which the RIS-UE 100B has four UE antennas 101a to 101d. The UE antennas 101a to 101d are electrically connected to the main body of the RIS-UE 100B via wiring (feeder lines) 102a to 102d. In the description of the embodiments, the UE antennas 101a to 101d will be simply referred to as UE antennas 101 when not particularly distinguished, and the wirings 102a to 102d will be simply referred to as wiring 102 when not particularly distinguished.

[0135] In the embodiment, a UE antenna 101 is disposed on the metasurface 510. That is, the UE antenna 101 is integrally configured with the metasurface 510. While FIG. 25 shows an example in which the UE antenna 101 is disposed on the main surface 510a of the metasurface 510, one or more UE antennas 101 may be disposed on the back surface 510b of the metasurface 510.

[0136] By placing the UE antenna 101 on the metasurface 510, it becomes easy to match the radio wave environment of the metasurface 510 with the radio wave environment of the UE antenna 101. When the RIS-UE 100B reports a measurement value of the reception quality of a signal received by the UE antenna 101 of the RIS-UE 100B to the gNB 200, the gNB 200 can regard the measurement value as a measurement value of the reception quality at the metasurface 510. For example, using the initial access and measurement report of the RIS-UE 100B, the gNB 200 can determine whether the radio waves of the gNB 200 are reaching the metasurface 510 and can also determine the characteristics of the beam incident on the metasurface 510 from the gNB 200. In addition, when RIS-UE100B reports to gNB200 the measured value of the reception quality of the signal received by UE antenna 101 of RIS-UE100B from UE100A, gNB200 can determine whether the uplink radio waves are reaching metasurface 510, and can also determine the characteristics of the beam incident on metasurface 510 from UE100A.

[0137] In this configuration example, the UE antenna 101 is disposed on the main surface 510a of the metasurface 510. This makes it easier for the UE antenna 101 to accurately grasp the state of the radio waves incident on the metasurface 510.

[0138] In this configuration example, the UE antenna 101 is arranged in an edge region of the main surface 510a of the metasurface 510. In the example of Fig. 25, the four UE antennas 101a to 101d are arranged at the four corners of the main surface 510a of the metasurface 510. By arranging the UE antennas 101 in this manner, it becomes easy to arrange the UE antennas 101 while avoiding the structures 511 provided on the metasurface 510. In the example of Fig. 25, a plurality of structures 511 are arranged in a matrix in the vertical and horizontal directions.

[0139] Furthermore, by arranging multiple UE antennas 101 on the metasurface 510, it becomes easier to estimate, for example, the direction of arrival of radio waves incident on the metasurface 510. Note that, although four UE antennas 101a to 101d are arranged in the example of FIG. 25, five or more UE antennas 101 may be arranged on the metasurface 510.

[0140] A plurality of UE antennas 101 may be arranged on both surfaces (main surface 510a and back surface 510b) of the metasurface 510. That is, at least one first antenna of the plurality of UE antennas 101 may be arranged on the main surface 510a, and at least one second antenna of the plurality of UE antennas 101 may be arranged on the back surface 510b. Such an arrangement makes it easy to distinguish between downlink and uplink for the metasurface 510 that transmits and refracts radio waves. For example, the surface with high downlink received power may be determined to be the gNB 200 side, and the surface with low downlink received power may be determined to be the UE 100A side, or the surface with high uplink received power may be determined to be the UE 100A side, and the surface with low uplink received power may be determined to be the gNB 200 side.

[0141] FIG. 26 is a diagram showing a second detailed configuration example of the RIS device 500 according to the embodiment.

[0142] 26, the area of ​​each UE antenna 101 may be larger than the area of ​​each structure 511 provided at a predetermined interval on the metasurface 510. For example, if the radio waves to be transmitted and received by the metasurface 510 are 28 GHz and the radio waves to be transmitted and received by the RIS-UE 100B are 800 MHz, the area of ​​the antenna 101 of the RIS-UE 100B needs to be larger. Note that each UE antenna 101 has a planar pattern that avoids the structures 511.

[0143] FIG. 27 is a diagram showing a detailed configuration example 3 of the RIS device 500 according to the embodiment.

[0144] 27, the antenna 101 of the RIS-UE 100B may be provided over the entire main surface 510a of the metasurface 510. Such a single UE antenna 101 has a planar pattern that avoids the structure 511.

[0145] 25 to 27, the metasurface 510 may be configured to resonate with the radio waves (e.g., 28 GHz) that the metasurface 510 transmits and receives and the radio waves (e.g., 800 MHz) that the RIS-UE 100B transmits and receives control signals. Alternatively, the metasurface 510 may be configured to share the same frequency with the antenna 101 of the RIS-UE 100B. For example, the radio waves that the metasurface 510 transmits and receives and the radio waves that the RIS-UE 100B transmits and receives control signals may have the same frequency (e.g., 28 GHz).

[0146] [Other embodiments] Once the RIS-UE 100B is connected to the gNB 200 or is under RIS control from the gNB 200, it is desirable for the RIS-UE 100B to maintain the RRC connected state. When the RIS-UE 100B transitions to the RRC inactive state or the RRC idle state (or when the RIS-UE 100B is powered on), the RIS-UE 100B may control the RIS device 500 to a transmission mode (refractive angle of 0 degrees) or characteristics as close to this as possible. This can prevent adverse effects, such as an unintentional narrowing of the existing coverage area, caused by the RIS device 500 not controlled by the gNB 200.

[0147] The above-mentioned 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.

[0148] 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 also be an LTE base station (eNB). The base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU (Distributed Unit) of the IAB node.

[0149] A program may be provided that causes a computer to execute each process performed by UE100 (RIS-UE100B) or gNB200. The program may be recorded on a computer-readable medium. The computer-readable medium can be used to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by UE100 (RIS-UE100B) or gNB200 may be integrated, and at least a part of UE100 (RIS-UE100B) or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC).

[0150] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention.

[0151] This application claims priority to Japanese Patent Application No. 2021-089633 (filed May 27, 2021), the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0152] 1: Mobile communication system 100:UE 100B:RIS-UE 110: Receiving unit 120: Transmitter 130: Control unit 140: Interface 200 :gNB 210: Transmission unit 220: Receiving unit 230: Control unit 240: Backhaul communication unit 500 :RIS device 510: RIS (Metasurface) 520: RIS control unit

Claims

1. A communication control method, comprising: receiving, by a first device, control information from a network node for controlling the first device; The first device changes a propagation state of radio waves from the network node based on the control information; The network node broadcasts access restriction information that restricts access from user equipment; the first device ignoring the received access restriction information. Communication control method.

2. 1. A first device, comprising: a receiving unit configured to receive control information for controlling the first device from a network node; a control unit that changes a propagation state of radio waves from the network node based on the control information, the receiving unit receives access restriction information broadcast from the network node, the access restriction information restricting access from user equipment; The control unit ignores the received access restriction information. First device.

3. a network node, a transmitter configured to transmit control information for controlling a first device that changes a propagation state of a radio wave from the network node to the first device; the transmission unit broadcasts access restriction information that restricts access from user devices; The access restriction information is ignored by the first device that receives the access restriction information. Network node.

4. A chipset for a first device, comprising: receiving control information from a network node for controlling the first device; a process of changing a propagation state of radio waves from the network node based on the control information; receiving access restriction information broadcast from the network node, the access restriction information restricting access from user equipment; and executing a process of ignoring the received access restriction information. Chipset.

5. The first device receiving control information from a network node for controlling the first device; a process of changing a propagation state of radio waves from the network node based on the control information; receiving access restriction information broadcast from the network node, the access restriction information restricting access from user equipment; and executing a process of ignoring the received access restriction information. program.

6. A mobile communication system, a network node; a first device, The first device is receiving control information from the network node for controlling the first device; the first device changes a propagation state of radio waves from the network node based on the control information; The network node broadcasts access restriction information that restricts access from user equipment; The first device ignores the received access restriction information. Mobile communication system.

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