Transmission path control device, base station, terminal device, control method, and communication method

Abstract

Provided is a transmission path control device having a structure composed of a plurality of elements whose characteristics pertaining to the reflection or transmission of an incoming radio wave can change. The transmission path control device comprises: an acquisition unit that acquires information about a channel estimation result of each of two or more elements among the plurality of elements; and a transmission unit that transmits channel information based on information about the channel estimation result.

Description

Transmission path control device, base station, terminal device, control method, and communication method

[0001] The present disclosure relates to a transmission path control device, a base station, a terminal device, a control method, and a communication method.

[0002] As demand for communications expands, the problem of radio wave resources (wireless resources) becoming depleted has become apparent. To address this problem, attention has been focused on technology that improves frequency utilization efficiency by dynamically changing radio wave propagation paths. Reconfigurable intelligent surfaces (RISs) are known as devices for changing propagation paths (hereinafter also referred to as transmission path control devices). The installation of RISs makes it possible, for example, to control the direction of radio wave reflection and form new propagation paths.

[0003] Japanese Patent Application Laid-Open No. 2022-117980

[0004] However, simply introducing a RIS may not fully realize effective use of radio wave resources. For example, in the past, in order to maintain communication quality, a communication device equipped in the RIS performs channel estimation operations. However, with this conventional channel estimation method, depending on the structure of the RIS, the channel estimation results may differ from the actual channel state. In this case, the quality of communication via the RIS cannot be guaranteed, and there is a possibility that effective use of radio wave resources may not be fully realized.

[0005] Therefore, the present disclosure proposes a transmission path control device, a base station, a terminal device, a control method, and a communication method that can realize effective use of radio wave resources.

[0006] It should be noted that the above problem or object is merely one of multiple problems or objects that can be solved or achieved by multiple embodiments disclosed in this specification.

[0007] In order to solve the above problems, one form of transmission path control device according to the present disclosure is a transmission path control device having a structure composed of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves, and is equipped with an acquisition unit that acquires information regarding the results of channel estimation for each of two or more elements among the plurality of elements, and a transmission unit that transmits channel information based on the information regarding the results of the channel estimation.

[0008] 1 is a diagram for explaining the structure of a RIS. A diagram showing how a RIS includes a communication unit. A diagram for explaining a RIS of the present embodiment. A diagram showing the configuration of a communication system according to the present embodiment. A diagram showing the configuration of a management device according to the present embodiment. A diagram showing the configuration of a base station according to the present embodiment. A diagram showing an example configuration of a transmission path control device according to an embodiment of the present disclosure. A diagram showing an example configuration of a surface unit included in the transmission path control device. A diagram showing the configuration of a terminal device according to the present embodiment. A flowchart showing channel estimation processing of the present embodiment. A sequence diagram showing channel estimation processing according to Example 1. A diagram for explaining an example operation of a RIS. A sequence diagram showing channel estimation processing according to Example 2. A diagram showing an example configuration of a RIS according to Example 2. A diagram showing an example operation of a RIS when elements performing channel estimation for frequency band #1 and elements performing channel estimation for frequency band #2 are alternately arranged. A diagram showing an example operation of a RIS when elements performing channel estimation for frequency band #1 and elements performing channel estimation for frequency band #2 are each arranged in half of the RIS. A diagram showing an example operation of a RIS when elements performing channel estimation for frequency band #1 and elements performing channel estimation for frequency band #2 are arranged in different ratios. A sequence diagram showing channel estimation processing according to Example 3. FIG. 10 is a sequence diagram illustrating a channel estimation process according to a fourth embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, the same components are designated by the same reference numerals, and redundant description will be omitted.

[0010] In addition, in this specification and drawings, multiple components having substantially the same functional configuration may be distinguished by adding different numbers to the same reference numeral. For example, multiple components having substantially the same functional configuration may be referred to as the transmission line control device 30 as needed. １ , 30 ２ , and 30 ３ However, when there is no need to particularly distinguish between multiple components having substantially the same functional configuration, only the same reference numerals are used. For example, the transmission line control device 30１ , 30 ２ , and 30 ３ When there is no need to particularly distinguish between them, they will be simply referred to as the transmission line control device 30.

[0011] One or more embodiments (including examples and variations) described below can be implemented independently. However, at least a portion of the embodiments described below may be implemented in appropriate combination with at least a portion of another embodiment. These embodiments may include novel features that are different from one another. Therefore, these embodiments may contribute to solving different purposes or problems and may produce different effects.

[0012] The present disclosure will be described in the following order: 1. Overview 1-1. Problem 1-2. Overview of the solution 2. Configuration of the communication system 2-1. Configuration of the management device 2-2. Configuration of the base station 2-3. Configuration of the transmission path control device 2-4. Configuration of the terminal device 3. Operation of the communication system 3-1. Channel estimation process 3-2. Capability information 3-3. Channel estimation form information 3-4. Channel information 3-5. Method of using channel information 4. Examples 4-1. Example 1 4-2. Example 2 4-3. Example 3 4-4. Example 4 5. Modified example 6. Conclusion

[0013] <<1. Overview>> As demand for communications expands, the problem of radio wave resources (wireless resources) becoming depleted has become apparent. To address this problem, attention has been focused on technology that improves frequency utilization efficiency by dynamically changing radio wave propagation paths. A known device for changing propagation paths (hereinafter also referred to as a transmission path control device) is a reconfigurable intelligent surface (RIS). A RIS is also called an intelligent reflecting surface (IRS) or an intelligent surface (IS).

[0014] FIG. 1 is a diagram illustrating the structure of a RIS. A RIS is a device including a structure (e.g., a reflector) composed of one or more metasurface elements whose permittivity and / or permeability can be dynamically controlled. A metasurface element is a type of artificial medium (metamaterial) that achieves any permittivity and / or permeability by periodically arranging structures that are small relative to the wavelength. A metasurface element is sometimes simply referred to as a metasurface. A RIS can control the amplitude, phase, polarization, or frequency of an incoming radio wave by manipulating the permittivity and / or permeability of the metasurface (metasurface element). A control device inside or outside the RIS can control the direction of the reflected wave to bypass an obstruction or form a new propagation path by controlling the reflected wave from the RIS.

[0015] <1-1. Issues> The introduction of RIS is expected to improve frequency utilization efficiency. However, simply introducing RIS may not fully realize effective utilization of radio wave resources. For example, in a conventional RIS, a communication device (e.g., a communication unit shown in FIG. 2) included in the RIS performs an operation for channel estimation (e.g., a sounding operation). FIG. 2 is a diagram showing how a RIS includes a communication unit. For example, in a conventional RIS, the communication unit included in the RIS performs a sounding operation of a channel between a base station and the RIS or between a terminal device and the RIS, and feeds back the sounding result to the base station or the terminal device as a channel estimation result.

[0016] However, in this conventional channel estimation method, depending on the structure of the RIS (for example, depending on the shape / size of the RIS), the actual channel state and the channel estimation result may deviate from the actual channel state. For example, when the size of the RIS is large, the content of the channel information acquired by the sounding operation of the communication unit may deviate significantly from the actual channel state. In this case, the quality of communication via the RIS cannot be guaranteed, and there is a possibility that radio wave resources will not be fully utilized effectively.

[0017] <1-2. Overview of Solution> Therefore, in this embodiment, the above problem is solved as follows.

[0018] The communication system of this embodiment includes one or more communication devices (e.g., base stations and / or terminal devices) and one or more RISs. FIG. 3 is a diagram for explaining the RIS of this embodiment. The RIS includes multiple elements (metasurface elements shown in FIG. 3) that can change the characteristics related to the reflection or transmission of incoming radio waves. In the RIS of this embodiment, a channel estimation unit is arranged in each of two or more of the multiple elements, as shown in FIG. 3, in addition to a phase shifter that manipulates reflected waves / transmitted waves. The elements in which the channel estimation unit is arranged may be all of the multiple elements included in the RIS, or may be some of the multiple elements. Note that a secondary modulation unit and / or an amplifier may also be arranged in the phase shifter.

[0019] The channel estimation unit performs an operation (e.g., a sounding operation) related to channel estimation at the arranged elements based on a channel estimation signal transmitted from the base station or the terminal device. The RIS control device acquires information on the channel estimation results from each channel estimation unit. The RIS control device then transmits channel information generated based on the information on the channel estimation results to the base station or the terminal device.

[0020] This makes it possible to perform channel estimation for each element. As a result, more accurate channel estimation is possible, and the RIS can control elements or form reflected beams more precisely. As a result, the base station / terminal device can perform high-quality communication via the RIS, thereby realizing effective use of radio wave resources.

[0021] The outline of this embodiment has been described above, and the communication system 1 of this embodiment will now be described in detail.

[0022] <<2. Configuration of the Communication System>> First, a specific description will be given of the configuration of the communication system 1. The configuration of the communication system 1 shown below is common to the first to fourth embodiments.

[0023] FIG. 4 is a diagram showing the configuration of a communication system 1 according to this embodiment. As shown in FIG. 4, the communication system 1 includes a management device 10, a base station 20, a transmission path control device 30, and a terminal device 40. The communication system 1 may include devices other than those shown in FIG. 4. For example, the communication system 1 may include a control station that controls the transmission path control device 30. The control station may perform centralized control of multiple transmission path control devices 30. The control device for the multiple transmission path control devices 30 is typically a control unit (e.g., a processor) included in the transmission path control device 30. However, the control station can also be considered as a control device for the transmission path control device 30.

[0024] The communication system 1 provides a wireless network (mobile network) that enables mobile communication for users by the cooperation of the wireless communication devices that make up the communication system 1. The wireless network of this embodiment may be, for example, a cellular network that includes a radio access network RAN ​​and a core network CN. The mobile network may include a terminal device 40. In this embodiment, the wireless communication device is a communication device that has a wireless communication function, and in the example of FIG. 4, this corresponds to the base station 20 and the terminal device 40.

[0025] The communication system 1 may include a plurality of management devices 10, a plurality of base stations 20, a plurality of transmission path control devices 30, and a plurality of terminal devices 40. In the example of FIG. 4, the communication system 1 includes a plurality of management devices 10. １ and management device 10 ２ and the base station 20 is provided with １ , base station 20 ２ , and base station 20 ３ In the example of FIG. 4, the communication system 1 includes a transmission line control device 30. １ , transmission path control device 30 ２ , and the transmission path control device 30 ３ The terminal device 40 is provided with the terminal device 40 １ , terminal device 40 ２ , and terminal device 40 ３ It is equipped with:

[0026] The terminal device 40 may be configured to connect to a network using radio access technology (RAT) such as LTE (Long Term Evolution), NR (New Radio), 6G, Wi-Fi, Bluetooth (registered trademark), etc. In this case, the terminal device 40 may be configured to be able to use different radio access technologies (wireless communication methods). For example, the terminal device 40 may be configured to be able to use NR and Wi-Fi. Furthermore, the terminal device 40 may be configured to be able to use different cellular communication technologies (e.g., LTE, NR, or 6G). In the following description, the terminal device 40 may be referred to as UE (User Equipment).

[0027] LTE and NR are types of cellular communication technologies that enable mobile communication for terminal devices by arranging multiple areas covered by base stations in the form of cells. 6G, also a type of cellular communication technology, has the potential to become a technology that enables mobile communication for terminal devices by arranging multiple areas covered by base stations in the form of cells.

[0028] In the following description, "LTE" includes LTE-A (LTE-Advanced), LTE-A Pro (LTE-Advanced Pro), and EUTRA (Evolved Universal Terrestrial Radio Access). NR includes NRAT (New Radio Access Technology) and FEUTRA (Further EUTRA). A single base station 20 may manage multiple cells. In the following description, a cell corresponding to LTE is referred to as an LTE cell, and a cell corresponding to NR is referred to as an NR cell.

[0029] NR is the next generation (5th generation) radio access technology after LTE (4th generation communications including LTE-Advanced and LTE-Advanced Pro). NR is a radio access technology that can support various use cases, including eMBB (Enhanced Mobile Broadband), mMTC (Massive Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communications). NR was standardized in 3GPP (registered trademark) Rel-15 as a technical framework that corresponds to the usage scenarios, requirements, and deployment scenarios of these use cases. Furthermore, beyond 5G and 6G, it is required to simultaneously achieve multiple axes of high speed, large capacity, low latency, high reliability, and multiple simultaneous connections.

[0030] 6G is the next generation of cellular communications technology after NR (5th generation mobile communications) and 5GS (5G system). 6G includes radio access technology and network technologies between base stations, core networks, and data networks. 6G also includes technologies for extreme connectivity of eMBB, mMTC, and URLLC, which were the main use cases or requirements of NR. 6G also includes new technologies in new areas. For example, 6G may include technologies related to AI (cognitive network, AI native air interface), sensing (including radar sensing and network as a sensor), and terahertz communications.

[0031] The wireless network may support at least one of radio access technologies (RATs) such as LTE (Long Term Evolution), NR (New Radio), and 6G. LTE, NR, and 6G are types of cellular communication technologies that enable mobile communication for terminal devices by arranging multiple areas covered by base stations in the form of cells. The wireless access method used by the communication system 1 is not limited to LTE, NR, and 6G, and may be other wireless access methods such as W-CDMA (Wideband Code Division Multiple Access) and cdma2000 (Code Division Multiple Access 2000).

[0032] Furthermore, the base station 20 may be a terrestrial station or a non-terrestrial station. The non-terrestrial station may be a satellite station or an aircraft station. If the non-terrestrial station is a satellite station, the wireless network may be a bent-pipe (transparent) type mobile satellite communication system.

[0033] In this embodiment, terrestrial stations and terrestrial base stations refer to base stations and relay stations installed on the ground. Here, "terrestrial" refers to terrestrial in a broad sense, including not only land but also underground, on water, and underwater. In the following description, the term "terrestrial station" may be replaced with "gateway."

[0034] Note that an LTE base station may be referred to as an eNodeB (Evolved Node B) or eNB. An NR base station may be referred to as a gNodeB or gNB. A 6G base station may be referred to as a 6G NodeB (6GNB). In LTE, NR, and 6G, a terminal device (also referred to as a mobile station or terminal) may be referred to as a UE (User Equipment). Note that a terminal device is a type of communication device and is also referred to as a mobile station or terminal.

[0035] The terminal device 40 may be able to connect to a network using a wireless access technology (wireless communication method) other than LTE, NR, 6G, Wi-Fi, or Bluetooth. For example, the terminal device 40 may be able to connect to a network using low power wide area (LPWA) communication. The terminal device 40 may also be able to connect to a network using proprietary wireless communication.

[0036] Here, LPWA communication refers to wireless communication that enables low-power, wide-range communication. For example, LPWA wireless refers to IoT (Internet of Things) wireless communication using a specified low-power radio (e.g., the 920 MHz band) or the ISM (Industry-Science-Medical) band. Note that the LPWA communication used by the terminal device 40 may be compliant with the LPWA standard. Examples of LPWA standards include ELTRES, ZETA, SIGFOX, LoRaWAN, and NB-IoT. Of course, the LPWA standard is not limited to these, and other LPWA standards may also be used.

[0037] Each wireless communication device shown in Fig. 4 may be considered as a device in a logical sense, i.e., a part of each wireless communication device may be realized by a virtual machine (VM), a container such as Docker, or the like, and these may be physically implemented on the same hardware.

[0038] In this embodiment, the concept of a wireless communication device includes not only portable mobile devices (terminal devices) such as mobile terminals, but also devices installed in structures or mobile bodies. The structures or mobile bodies themselves may be considered wireless communication devices. Furthermore, the concept of a wireless communication device includes not only terminal devices 40 but also base stations 20. A wireless communication device is a type of processing device or information processing device. A wireless communication device can also be referred to as a transmitting device or a receiving device.

[0039] The following describes in detail the configuration of each wireless communication device that makes up the communication system 1. Note that the configuration of each wireless communication device shown below is merely an example. The configuration of each wireless communication device may be different from the configuration shown below.

[0040] 2-1. Configuration of Management Device First, the configuration of the management device 10 will be described.

[0041] The management device 10 is an information processing device (computer) that manages a wireless network. For example, the management device 10 is an information processing device that manages communications of the base station 20. The management device 10 is also a type of communication device.

[0042] The management device 10 may be, for example, a device having a function as an MME (Mobility Management Entity). The management device 10 may also be a device having a function as an AMF (Access and Mobility Management Function) and / or an SMF (Session Management Function). The MME, AMF, and SMF are control plane network function nodes in a core network. The management device 10 may be a device having a function as a control plane network function (6G CPNF) in 6G. The 6G CPNF may be composed of one or more logical nodes.

[0043] Of course, the functions of the management device 10 are not limited to MME, AMF, SMF, and 6G CPNF. The management device 10 may be a device having functions as a Network Slice Selection Function (NSSF), an Authentication Server Function (AUSF), a Policy Control Function (PCF), and a Unified Data Management (UDM). Furthermore, the management device 10 may be a device having functions as a Home Subscriber Server (HSS).

[0044] The management device 10 may have a gateway function. For example, the management device 10 may have a function as an S-GW (Serving Gateway) or a P-GW (Packet Data Network Gateway). The management device 10 may also have a UPF (User Plane Function) function. In this case, the management device 10 may have multiple UPFs. The management device 10 may also be a device that has a function as a 6G User Plane Network Function (6G UPNF).

[0045] The core network is composed of multiple network functions, and each network function may be consolidated into one physical device or distributed across multiple physical devices. In other words, the management device 10 may be distributed across multiple devices. Furthermore, this distributed distribution may be controlled so that it is executed dynamically. The base station 20 and the management device 10 form a single network, providing wireless communication services to terminal devices 40. The management device 10 is connected to the Internet, and the terminal devices 40 can use various services provided via the Internet via the base station 20.

[0046] The management device 10 does not necessarily have to be a device that constitutes a core network. For example, assume that the core network is a W-CDMA (Wideband Code Division Multiple Access) or cdma2000 (Code Division Multiple Access 2000) core network. In this case, the management device 10 may be a device that functions as an RNC (Radio Network Controller).

[0047] FIG. 5 is a diagram showing the configuration of the management device 10 according to this embodiment. The management device 10 includes a communication unit 11, a storage unit 12, and a control unit 13. The configuration shown in FIG. 5 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the management device 10 may be statically or dynamically distributed and implemented in multiple physically separated configurations. The management device 10 may also be configured by multiple server devices.

[0048] The communication unit 11 is a communication interface for communicating with other communication devices (e.g., the base station 20). The communication unit 11 may be a network interface or a device connection interface. The communication unit 11 may be a LAN (Local Area Network) interface such as a NIC (Network Interface Card), or a USB (Universal Serial Bus) interface configured by a USB host controller or a USB port. The communication unit 11 may be a wired interface or a wireless interface. The communication unit 11 functions as a communication means of the management device 10. The communication unit 11 is controlled by the control unit 13.

[0049] The storage unit 12 is a readable and writable storage device such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, or a hard disk. The storage unit 12 functions as a storage means of the management device 10. The storage unit 12 stores, for example, the connection status of the terminal device 40. The storage unit 12 stores the status of the radio resource control (RRC) of the terminal device 40 and the status of the EPS connection management (ECM) or the 5G system connection management (CM). The storage unit 12 may function as a home memory that stores location information of the terminal device 40. The storage unit 12 also stores a learning model (prediction model) for predicting the future quality of the mobile network. The learning model will be described later.

[0050] The control unit 13 is a controller that controls each component of the management device 10. The control unit 13 may be implemented by a processor such as a central processing unit (CPU) or a microprocessing unit (MPU). Specifically, the control unit 13 may be implemented by a processor executing various programs stored in a storage device internal to the management device 10 using a random access memory (RAM) or the like as a work area. The control unit 13 may be implemented by an integrated circuit such as an application-specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The control unit 13 may also be implemented by a graphics processing unit (GPU). A CPU, an MPU, an ASIC, an FPGA, and a GPU can all be considered controllers. The control unit 13 may be configured by multiple physically separated entities. For example, the control unit 13 may be configured by multiple semiconductor chips.

[0051] The operation of the control unit 13 may be similar to the operation of the control unit 23 of the base station 20 and the control unit 43 of the terminal device 40 .

[0052] <2-2. Configuration of Base Station> Next, the configuration of the base station 20 will be described.

[0053] The base station 20 is a wireless communication device that performs wireless communication with other wireless communication devices (e.g., terminal devices 40 or other base stations 20). The base station 20 may perform wireless communication with the terminal devices 40 via a relay station, or may perform wireless communication directly with the terminal devices 40.

[0054] The base station 20 is a device equivalent to a radio base station (e.g., base station, Node B, eNB, gNB, or 6GNB) or a radio access point. The base station 20 may be a radio relay station. The base station 20 may be an optical device called an RRH (Remote Radio Head). The base station 20 may be a receiving station such as an FPU (Field Pickup Unit). The base station 20 may be an IAB (Integrated Access and Backhaul) donor node or an IAB relay node that provides radio access lines and radio backhaul lines using time division multiplexing, frequency division multiplexing, or space division multiplexing.

[0055] The wireless access technology used by the base station 20 may be cellular communication technology. The wireless access technology used by the base station 20 may be wireless LAN technology. The wireless access technology used by the base station 20 may be low-power wide-area (LPWA) communication technology. However, the wireless access technology used by the base station 20 is not limited to these and may be other wireless access technologies. The wireless communication used by the base station 20 may be wireless communication using millimeter waves or wireless communication using terahertz waves. The wireless communication used by the base station 20 may be wireless communication using radio waves or wireless communication using infrared or visible light (optical wireless). Furthermore, the base station 20 may be capable of NOMA (Non-Orthogonal Multiple Access) communication with the terminal device 40. Here, NOMA communication refers to communication (transmission, reception, or both) using non-orthogonal resources. Note that the base station 20 may be capable of NOMA communication with other base stations 20.

[0056] The base station 20 may be able to communicate with the core network via a base station-core network interface (e.g., NG Interface, S1 Interface, etc.). This interface may be either wired or wireless. The base station may also be able to communicate with other base stations via an inter-base station interface (e.g., Xn Interface, X2 Interface, F1 Interface, etc.). This interface may be either wired or wireless.

[0057] The concept of a base station (also called a "base station device") includes not only a donor base station but also a relay base station (also called a "relay station"). A relay base station may be any one of an RF Repeater, a Smart Repeater, and an Intelligent Surface. The concept of a base station includes not only a structure with base station functions but also equipment installed in the structure.

[0058] Examples of structures include high-rise buildings, houses, steel towers, station facilities, airport facilities, port facilities, office buildings, school buildings, hospitals, factories, commercial facilities, stadiums, and other buildings. The concept of a structure includes not only buildings, but also non-building structures such as tunnels, bridges, dams, fences, and steel pillars, as well as equipment such as cranes, gates, and wind turbines. The concept of a structure includes not only land (ground in the narrow sense) or underground structures, but also water-based structures such as piers or megafloats, and underwater structures such as ocean observation facilities. A base station can also be referred to as an information processing device.

[0059] The base station 20 may be a donor station or a relay station (relay station). The base station 20 may also be a fixed station or a mobile station. A mobile station is a wireless communication device (e.g., a base station) configured to be mobile. In this case, the base station 20 may be a device installed in a mobile body, or may be the mobile body itself. For example, a relay station with mobility can be considered as the base station 20 as a mobile station. Furthermore, devices that are inherently mobile and have base station functionality (at least part of the base station functionality), such as vehicles, UAVs (Unmanned Aerial Vehicles) represented by drones, and smartphones, also fall under the category of the base station 20 as a mobile station.

[0060] Here, the moving body may be a mobile terminal such as a smartphone or a mobile phone. The moving body may be a moving body that moves on land (ground in the narrow sense) (e.g., a vehicle such as an automobile, bicycle, bus, truck, motorcycle, train, or linear motor car), or a moving body that moves underground (e.g., in a tunnel) (e.g., a subway). The moving body may also be a moving body that moves on water (e.g., a ship such as a passenger ship, cargo ship, or hovercraft), or a moving body that moves underwater (e.g., a submersible vessel such as a submarine, submarine, or unmanned underwater vehicle). The moving body may also be a moving body that moves within the atmosphere (e.g., an aircraft such as an airplane, airship, or drone).

[0061] The base station 20 may be a terrestrial base station (ground station) installed on the ground. The base station 20 may be a base station located on a structure on the ground, or a base station installed on a mobile object moving on the ground. The base station 20 may be an antenna installed on a structure such as a building and a signal processing device connected to that antenna. The base station 20 may be the structure or the mobile object itself. "Ground" refers not only to land (ground in the narrow sense) but also to ground, on water, and underwater in a broad sense. The base station 20 is not limited to a terrestrial base station. If the communication system 1 is a satellite communication system, the base station 20 may be an aircraft station. From the perspective of a satellite station, an aircraft station located on Earth is a ground station.

[0062] The base station 20 is not limited to a ground station. The base station 20 may be a non-terrestrial base station device (non-terrestrial station) that can float in the air or space. The base station 20 may be an aircraft station or a satellite station.

[0063] A satellite station is a satellite station capable of floating outside the atmosphere. The satellite station may be a device mounted on a space vehicle such as an artificial satellite, or may be the space vehicle itself. A space vehicle is a vehicle that moves outside the atmosphere. Examples of space vehicles include artificial celestial bodies such as artificial satellites, spacecraft, space stations, and probes. A satellite that serves as a satellite station may be a low Earth orbiting (LEO) satellite, a medium Earth orbiting (MEO) satellite, a geostationary Earth orbiting (GEO) satellite, or a highly elliptical orbiting (HEO) satellite. The satellite station may be a device mounted on a low Earth orbit satellite, a medium Earth orbit satellite, a geostationary satellite, or a highly elliptical orbit satellite.

[0064] An aircraft station is a wireless communication device capable of floating in the atmosphere of an aircraft or the like. The aircraft station may be a device mounted on the aircraft or the like, or may be the aircraft itself. The concept of aircraft includes not only heavier-than-air vehicles such as airplanes and gliders, but also lighter-than-air vehicles such as balloons and airships. The concept of aircraft includes not only heavier-than-air vehicles or lighter-than-air vehicles, but also rotorcraft such as helicopters and autogyros. The aircraft station, or an aircraft equipped with an aircraft station, may be an unmanned aerial vehicle such as a drone.

[0065] The concept of unmanned aerial vehicles also includes unmanned aerial systems (UAS) and tethered unmanned aerial systems (UAS). The concept of unmanned aerial vehicles also includes lighter than air UAS (LTA) and heavier than air UAS (HTA). The concept of unmanned aerial vehicles also includes high altitude unmanned aerial system platforms (HAPs).

[0066] The coverage size of the base station 20 may be relatively large, such as a macrocell, or relatively small, such as a picocell. The coverage size of the base station 20 may be extremely small, such as a femtocell. The base station 20 may have a beamforming function. The base station 20 may form a cell or service area for each beam. Additionally or alternatively, in addition to beamforming, which gives directionality to a beam, the base station 20 may have a function for pinpointing a desired wave to a specific point by further considering distance information from the antenna of the base station 20. This function may be called beam focusing or point forming.

[0067] FIG. 6 is a diagram showing the configuration of a base station 20 according to this embodiment. The base station 20 includes a wireless communication unit 21, a storage unit 22, a control unit 23, and a sensor unit 24. The base station 20 does not necessarily have to include all of these components. For example, the base station 20 does not necessarily have to include the sensor unit 24. Note that the configuration shown in FIG. 6 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the base station 20 may be distributed and implemented across multiple physically separated components.

[0068] The wireless communication unit 21 is a signal processing unit for wireless communication with other wireless communication devices (for example, terminal devices 40 or other base stations 20). The wireless communication unit 21 is controlled by the control unit 23. The wireless communication unit 21 supports one or more wireless access methods. The wireless communication unit 21 may support at least one of NR, LTE, and 6G. In addition to NR, LTE, and 6G, the wireless communication unit 21 may also support W-CDMA, cdma2000, and the like. The wireless communication unit 21 may also support automatic retransmission techniques such as HARQ (Hybrid Automatic Repeat reQuest).

[0069] The wireless communication unit 21 includes a transmission processing unit 211, a reception processing unit 212, and an antenna 213. The wireless communication unit 21 may include a plurality of transmission processing units 211, reception processing units 212, and antennas 213. When the wireless communication unit 21 supports a plurality of wireless access methods, each unit of the wireless communication unit 21 may be configured separately for each wireless access method. The transmission processing unit 211 and the reception processing unit 212 may be configured separately for LTE, NR, and 6G. The antenna 213 may be configured with a plurality of antenna elements, for example, a plurality of patch antennas. The wireless communication unit 21 may have a beamforming function. For example, the wireless communication unit 21 may have a polarization beamforming function using vertical polarization (V polarization) and horizontal polarization (H polarization) (or a polarization beamforming function using dual polarization in polarization directions 45 degrees and -45 degrees from the vertical direction).

[0070] The transmission processing unit 211 performs transmission processing of downlink control information and downlink data. For example, the transmission processing unit 211 encodes the downlink control information and downlink data input from the control unit 23 using a coding method such as block coding, convolutional coding, or turbo coding. Here, the encoding may be performed using polar codes or low density parity check codes (LDPC codes). The transmission processing unit 211 then modulates the coded bits using a predetermined modulation method such as BPSK, QPSK, 16QAM, 64QAM, or 256QAM. In this case, the signal points on the constellation do not necessarily need to be equidistant. The constellation may be a non-uniform constellation (NUC). The transmission processing unit 211 then multiplexes the modulation symbols of each channel and the downlink reference signal and allocates them to predetermined resource elements. The transmission processing unit 211 then performs various signal processing on the multiplexed signal. For example, the transmission processing unit 211 performs processes such as conversion to the frequency domain by fast Fourier transform, addition of a guard interval (cyclic prefix), generation of a baseband digital signal, conversion to an analog signal, quadrature modulation, up-conversion, removal of unnecessary frequency components, power amplification, etc. The signal generated by the transmission processing unit 211 is transmitted from an antenna 213.

[0071] The reception processing unit 212 processes the uplink signal received via the antenna 213. For example, the reception processing unit 212 performs downconversion, removal of unnecessary frequency components, control of amplification level, quadrature demodulation, conversion to a digital signal, removal of guard intervals (cyclic prefixes), extraction of frequency domain signals by fast Fourier transform, and the like on the uplink signal. The reception processing unit 212 then separates uplink channels such as a PUSCH (Physical Uplink Shared Channel) and a PUCCH (Physical Uplink Control Channel) and an uplink reference signal from the signal that has undergone these processes. Furthermore, the reception processing unit 212 demodulates the received signal using a modulation method such as BPSK (Binary Phase Shift Keying) or QPSK (Quadrature Phase Shift Keying) for the modulation symbols of the uplink channel. The modulation method used for demodulation may be 16QAM (Quadrature Amplitude Modulation), 64QAM, or 256QAM. In this case, the signal points on the constellation do not necessarily have to be equidistant. The constellation may be a non-uniform constellation (NUC). The reception processing unit 212 then performs decoding processing on the coded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the control unit 23.

[0072] The antenna 213 is an antenna device that converts electric current and radio waves into each other. The antenna 213 may be configured with one antenna element, for example, one patch antenna. The antenna 213 may be configured with multiple antenna elements, for example, multiple patch antennas. When the antenna 213 is configured with multiple antenna elements, the wireless communication unit 21 may have a beamforming function. The wireless communication unit 21 may be configured to generate a directional beam by controlling the directivity of a wireless signal using the multiple antenna elements. The antenna 213 may be a dual-polarized antenna. When the antenna 213 is a dual-polarized antenna, the wireless communication unit 21 may use vertical polarization (V polarization) and horizontal polarization (H polarization) (or dual polarization with polarization directions at 45 degrees and -45 degrees from the vertical direction) when transmitting a wireless signal. The wireless communication unit 21 may control the directivity of a wireless signal transmitted using vertical polarization and horizontal polarization (or dual polarization with polarization directions at 45 degrees and -45 degrees from the vertical direction). Furthermore, the wireless communication unit 21 may transmit and receive spatially multiplexed signals via multiple layers each consisting of multiple antenna elements.

[0073] The storage unit 22 is a readable and writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 22 functions as a storage means of the base station 20.

[0074] The control unit 23 is a controller that controls each unit of the base station 20. The control unit 23 controls the wireless communication unit to perform wireless communication with other wireless communication devices (e.g., terminal devices 40 or other base stations 20). The control unit 23 may be implemented by a processor such as a CPU or MPU. Specifically, the control unit 23 may be implemented by a processor executing various programs stored in a storage device inside the base station 20 using RAM or the like as a work area. The control unit 23 may be implemented by an integrated circuit such as an ASIC or FPGA. The control unit 23 may also be implemented by a GPU. A CPU, MPU, ASIC, FPGA, and GPU can all be considered controllers. The control unit 23 may be composed of multiple physically separated objects. For example, the control unit 23 may be composed of multiple semiconductor chips.

[0075] The control unit 23 includes an acquisition unit 231, a transmission unit 232, and a communication control unit 233. Each block (acquisition unit 231 to communication control unit 233) constituting the control unit 23 is a functional block that indicates a function of the control unit 23. These functional blocks may be software blocks or hardware blocks. For example, each of the above-mentioned functional blocks may be a software module realized by software (including a microprogram), or may be a circuit block on a semiconductor chip (die). Of course, each functional block may be a processor or an integrated circuit. The control unit 23 may be configured with functional units different from the above-mentioned functional blocks. The method of configuring the functional blocks is arbitrary.

[0076] The operation of each block constituting the control unit 23 may be similar to the operation of each block provided in the control unit 43 of the terminal device 40. The operation of the control unit 23 may also be similar to the operation of the control unit 13 of the management device 10.

[0077] The sensor unit 24 is a sensor that acquires various information related to wireless communication. For example, the sensor unit 24 is a sensor that acquires information about objects around the device. For example, the sensor unit 24 is a sensor that acquires information about the position, shape, movement, etc. of another object (for example, a third object, a communication device that constitutes a communication link, or a third communication device). The sensor unit 24 may be a sensor for detecting the state of the device itself (for example, the position, movement speed, tilt, vibration, rotation, etc. of the base station 20).

[0078] The sensor unit 24 is a sensor that acquires various information related to wireless communication. For example, the sensor unit 24 is a sensor that acquires information about objects around the device. For example, the sensor unit 24 is a sensor that acquires information about the position, shape, movement, etc. of other objects. The sensor unit 24 may be a sensor that detects the state of the device itself (for example, the position, movement speed, tilt, vibration, rotation, etc. of the base station 20).

[0079] The sensor unit 24 may be an RF (Radio Frequency) sensor or a non-RF sensor. Alternatively, the sensor unit 24 may be a sensor system (for example, a sensor unit or a sensor module) that combines an RF sensor and a non-RF sensor.

[0080] Here, an RF sensor refers to a component that uses radio waves for measurement. An example of an RF sensor is a radar that uses radio waves such as millimeter waves. In this case, the radio waves used by the radar are not limited to radio waves in the millimeter wave band (e.g., 30 to 300 GHz band), but may also be radio waves in the microwave band (e.g., 3 to 30 GHz band) or quasi-millimeter wave band (e.g., 20 to 30 GHz band).

[0081] Another example of an RF sensor is a wireless positioning sensor (wireless positioning system). An example of a wireless positioning sensor is a Global Navigation Satellite System (GNSS) sensor. The GNSS sensor may be a Global Positioning System (GPS) sensor, a GLONASS sensor, a Galileo sensor, or a Quasi-Zenith Satellite System (QZSS) sensor. The wireless positioning sensor is not limited to a GNSS sensor, and may be, for example, a sensor for 3GPP positioning or Wi-Fi / Bluetooth positioning.

[0082] A non-RF sensor refers to a component that performs measurements without using radio waves. An example of a non-RF sensor is a ranging sensor (ranging system) such as LiDAR (Light Detection and Ranging). In this case, the light (e.g., laser light) used by the ranging sensor is not limited to visible light, and may be invisible light such as ultraviolet light, infrared light, or near-infrared light. Another example of a non-RF sensor is sonar that uses sound waves such as ultrasound.

[0083] Another example of a non-RF sensor is a camera. The camera is not limited to a visible light camera. For example, the camera may be a near-infrared camera, a mid-infrared camera, or a far-infrared camera. The camera may be a monocular camera or a stereo camera. Another example of a non-RF sensor may be an image sensor. In this case, the image sensor may have image plane phase difference pixels embedded discretely. Alternatively, the sensor unit 24 may be a ToF (Time of Flight) sensor or a microphone.

[0084] Other examples of non-RF sensors include an acceleration sensor (e.g., a three-axis acceleration sensor), a speed sensor, a gyro sensor, an IMU (Inertial Measurement Unit), and other motion sensors. Other examples of non-RF sensors include a magnetic sensor, a barometer, and an altimeter (e.g., a barometer).

[0085] Furthermore, the sensor unit 24 may be a sensor that acquires various information for predicting the quality of a communication path (e.g., a communication path formed by a wireless communication unit). For example, the sensor unit 24 is a sensor that detects the reception S / N of radio waves received from another communication device (e.g., a communication device that is a communication partner, or a communication device other than the communication partner). Of course, the information acquired by the sensor unit 24 is not limited to the reception S / N, as long as it can be used to predict the quality of the communication path.

[0086] Of course, the sensor unit 24 is not limited to the above-mentioned sensors, and may be a sensor system that combines a plurality of the above-mentioned sensors.

[0087] In some embodiments, the base station 20 may be configured as a collection of multiple physical or logical devices. As an example, the base station 20 of this embodiment may be divided into multiple devices such as a baseband unit (BBU) and a radio unit (RU). The base station 20 may be interpreted as a collection of these multiple devices. Furthermore, the base station may be either a BBU or an RU, or may be both. The BBU and the RU may be connected by a predetermined interface such as an enhanced Common Public Radio Interface (eCPRI).

[0088] The RU may be referred to as an RRU (Remote Radio Unit) or an RD (Radio DoT). The RU may correspond to a gNB-DU (gNB Distributed Unit) described later. The BBU may correspond to a gNB-CU (gNB Central Unit) described later. The RU may be a device integrally formed with an antenna. The antenna of the base station 20, for example, an antenna integrally formed with the RU, may employ an Advanced Antenna System and support MIMO such as FD-MIMO or beamforming. The antenna of the base station 20 may include, for example, 64 transmitting antenna ports and 64 receiving antenna ports.

[0089] The antenna mounted on the RU may be an antenna panel consisting of one or more antenna elements, and the RU may be equipped with one or more antenna panels. The RU may be equipped with two types of antenna panels, a horizontally polarized antenna panel and a vertically polarized antenna panel. The RU may be equipped with two types of antenna panels, a right-handed circularly polarized antenna panel and a left-handed circularly polarized antenna panel, or an antenna panel with a polarization direction at 45 degrees from the vertical direction and an antenna panel with a polarization direction at -45 degrees from the vertical direction. Multiple antennas with these multiple polarization directions may be mounted on a single antenna panel. The RU may form and control an independent beam for each antenna panel.

[0090] A plurality of base stations 20 may be connected to each other. One or more base stations 20 may be included in a radio access network (RAN). In this case, the base station 20 may be simply referred to as a RAN, a RAN node, an AN (Access Network), an AN node, or the like. The RAN in LTE may be called an Enhanced Universal Terrestrial RAN (EUTRAN). The RAN in NR may be called an NGRAN. Furthermore, the RAN in 6G may be called a 6GRAN. The RAN in W-CDMA (UMTS) may be called a UTRAN.

[0091] An LTE base station 20 may be referred to as an eNodeB (Evolved Node B) or eNB. In this case, the EUTRAN includes one or more eNodeBs (eNBs). An NR base station 20 may be referred to as a gNodeB or gNB. In this case, the NGRAN includes one or more gNBs. A 6G base station may be referred to as a 6GNodeB, 6gNodeB, 6GNB, or 6gNB. In this case, the 6GRAN includes one or more 6GNBs. The EUTRAN may include a gNB (en-gNB) connected to a core network (EPC) in an LTE communication system (EPS). The NGRAN may include an ng-eNB connected to a core network 5GC in a 5G communication system (5GS).

[0092] When the base station 20 is an eNB, gNB, 6GNB, or the like, the base station 20 may be referred to as a 3GPP access. When the base station 20 is a wireless access point, the base station 20 may be referred to as a non-3GPP access. The base station 20 may be a radio device called an RRH (Remote Radio Head). When the base station 20 is a gNB, the base station 20 may be a combination of the gNB-CU and gNB-DU described above, or may be either a gNB-CU or a gNB-DU.

[0093] Here, the gNB-CU hosts multiple upper layers (e.g., RRC (Radio Resource Control), SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol)) of the access stratum for communication with the UE. On the other hand, the gNB-DU hosts multiple lower layers (e.g., RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical layer)) of the access stratum. That is, among the messages / information described below, RRC signaling (semi-static notification) is generated by the gNB-CU, while MAC The CE and DCI (dynamic notification) may be generated by the gNB-DU. Alternatively, some configurations of the RRC configuration (semi-static notification), such as IE:cellGroupConfig, may be generated by the gNB-DU, and the remaining configurations may be generated by the gNB-CU. These configurations may be transmitted and received over the F1 interface described below.

[0094] The base station 20 may be configured to be able to communicate with other base stations. When multiple base stations 20 are eNBs or a combination of eNBs and en-gNBs, these base stations 20 may be connected to each other via an X2 interface. When multiple base stations 20 are gNBs or a combination of gn-eNBs and gNBs, these base stations 20 may be connected to each other via an Xn interface. When multiple base stations 20 are a combination of gNB-CUs and gNB-DUs, these base stations 20 may be connected to each other via the above-mentioned F1 interface. Messages / information (e.g., RRC signaling, MAC Control Element (CE), or Downlink Control Information (DCI)) described below may be transmitted between multiple base stations 20 via, for example, the X2 interface, the Xn interface, or the F1 interface.

[0095] A cell provided by the base station 20 may be referred to as a serving cell. The concept of a serving cell includes a PCell (Primary Cell) and an SCell (Secondary Cell). When dual connectivity is provided to the terminal device 40, a PCell and zero or more SCells provided by a Master Node (MN) may be referred to as a Master Cell Group. Examples of dual connectivity include EUTRA-EUTRA Dual Connectivity, EUTRA-NR Dual Connectivity (ENDC), EUTRA-NR Dual Connectivity with 5GC, NR-EUTRA Dual Connectivity (NEDC), and NR-NR Dual Connectivity. Further examples of dual connectivity include NR-6G Dual Connectivity and 6G-NR Dual Connectivity.

[0096] The serving cell may include a PSCell (Primary Secondary Cell or Primary SCG Cell). When dual connectivity is provided to the terminal device 40, the PSCell provided by a Secondary Node (SN) and zero or more SCells may be referred to as a Secondary Cell Group (SCG). Unless special configuration (e.g., PUCCH on SCell) is performed, the Physical Uplink Control Channel (PUCCH) is transmitted by the PCell and PSCell but not by the SCell. Radio link failure is detected by the PCell and PSCell but not (does not need to be detected by) the SCell. As such, the PCell and PSCell play special roles among serving cells and are therefore also referred to as Special Cells (SpCells).

[0097] One cell may be associated with one downlink component carrier and one uplink component carrier. The system bandwidth corresponding to one cell may be divided into multiple BWPs (Bandwidth Parts). In this case, one or multiple BWPs may be configured in the terminal device 40, and one BWP may be used by the terminal device 40 as an active BWP. Radio resources available to the terminal device 40, such as frequency bands, numerology (subcarrier spacing), or slot formats, may differ for each cell, component carrier, or BWP.

[0098] <2-3. Configuration of Transmission Line Control Device> Next, the configuration of the transmission line control device 30 will be described.

[0099] The transmission path control device 30 is a control device that dynamically changes the propagation path of radio waves. The transmission path control device 30 is typically a Reconfigurable Intelligent Surface (RIS). In this case, the RIS may be a RIS that operates in cooperation with a transceiver such as a base station (referred to as a Cooperative RIS in this embodiment), or a RIS that operates without cooperation with a transceiver (referred to as a Blind RIS in this embodiment). The RIS may also be a RIS that reflects incoming radio waves without amplifying them (referred to as a passive RIS in this embodiment), or a RIS that amplifies and reflects incoming radio waves (referred to as an active RIS in this embodiment). The transmission path control device 30 may be a device called a metasurface reflector or a device called a smart repeater. The transmission path control device 30 is not limited to a reflective device and may be, for example, a transmissive device. The transmission path control device 30 appearing in the following description can be rephrased as RIS, IRS, IS, metasurface, smart surface, intelligent surface, metamaterial, or the like.

[0100] The transmission line control device 30 has a structure that reflects or transmits the incoming radio waves. For example, the transmission line control device 30 may have, as the structure, a reflector formed of one or more metasurfaces (metasurface elements) that can dynamically control the permittivity and / or magnetic permeability. The transmission line control device 30 may also have, as the structure, a transmitting plate that can control the refractive index, etc., of the radio waves that pass through. The transmission line control device 30 then controls the reflection characteristics (e.g., reflection direction / reflectance, etc.) or transmission characteristics (e.g., refraction direction / transmittance, etc.) of the structure, thereby reflecting or transmitting the incoming radio waves at a desired angle.

[0101] The transmission path control device 30 may be a device installed on the outer wall of a structure such as a building. By installing the transmission path control device 30 on the outer wall of the structure, even if there is an obstruction between the base station 20 and the terminal device 40, a signal from the base station 20 can be reflected by the transmission path control device 30 provided on the outer wall of the building and reach the terminal device 40. The transmission path control device 30 may also be a device mounted on a device. In this case, the transmission path control device 30 may be a mobile device. The mobile device may be a floating device. For example, the transmission path control device 30 may be mounted on a terminal device such as a smartphone, a vehicle such as an automobile, a train, or a rickshaw, an air vehicle (floating body) such as a balloon, an airplane, or a drone, a facility such as a traffic light, a sign, or a street light, or a home appliance such as a television, a game console, an air conditioner, a refrigerator, or a lighting fixture.

[0102] FIG. 7 is a diagram illustrating an example configuration of a transmission path control device 30 according to an embodiment of the present disclosure. The transmission path control device 30 includes a communication unit 31, a storage unit 32, a control unit 33, a sensor unit 34, and a surface unit 35. The transmission path control device 30 does not necessarily include all of these components. For example, the transmission path control device 30 does not necessarily include the sensor unit 34. The transmission path control device 30 may also include a plurality of these components. For example, the transmission path control device 30 may include a plurality of surface units 35. In this case, the plurality of surface units 35 may face different directions. Note that the configuration illustrated in FIG. 7 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the transmission path control device 30 may be distributed and implemented in a plurality of physically separated components.

[0103] The communication unit 31 is a communication interface for communicating with other communication devices (for example, the management device 10, the base station 20, the terminal device 40, or another transmission path control device 30). The communication unit 31 may be a network interface or a device connection interface. The communication unit 31 may be a LAN (Local Area Network) interface such as a NIC (Network Interface Card), or a USB (Universal Serial Bus) interface configured by a USB host controller or a USB port. The communication unit 31 may be a wired interface or a wireless interface. The communication unit 31 is controlled by the control unit 33.

[0104] The storage unit 32 is a storage device that can read and write data, such as a DRAM, an SRAM, a flash memory, or a hard disk.

[0105] The control unit 33 is a controller (control device) that controls each unit of the transmission path control device 30. The control unit 33 is realized by a processor such as a CPU, MPU, or GPU. For example, the control unit 33 is realized by a processor executing various programs stored in a storage device inside the transmission path control device 30 using RAM or the like as a work area. The control unit 33 may be realized by an integrated circuit such as an ASIC or FPGA. The control unit 33 may also be realized by a GPU. A CPU, MPU, ASIC, FPGA, and GPU can all be considered controllers. The control unit 33 may be composed of multiple physically separated objects. For example, the control unit 33 may be composed of multiple semiconductor chips.

[0106] The control unit 33 includes an acquisition unit 331, a transmission unit 332, a channel estimation control unit 333, a reception unit 334, and an interpolation unit 335. Each block (acquisition unit 331 to interpolation unit 335) constituting the control unit 33 is a functional block that indicates the function of the control unit 33. These functional blocks may be software blocks or hardware blocks. For example, each of the above-mentioned functional blocks may be a software module realized by software (including a microprogram), or may be a circuit block on a semiconductor chip (die). Of course, each functional block may be a processor or an integrated circuit. The control unit 33 may be configured with functional units different from the above-mentioned functional blocks. The method of configuring the functional blocks is arbitrary.

[0107] The operation of the control unit 33 may be similar to the operation of the control unit 23 of the base station 20 and the control unit 43 of the terminal device 40. The operation of the control unit 33 may also be similar to the operation of the control unit 13 of the management device 10. The control unit 33 may also be configured to control the surface unit 35 of one or more other transmission path control devices 30.

[0108] The sensor unit 34 is a sensor that acquires various information related to wireless communication. For example, the sensor unit 34 is a sensor that acquires information about objects around the device. For example, the sensor unit 34 is a sensor that acquires information about the position, shape, movement, etc. of other objects. The sensor unit 34 may be a sensor that detects the state of the device itself (for example, the position, movement speed, tilt, vibration, rotation, etc. of the terminal device 40). Alternatively, the configuration of the sensor unit 34 may be the same as the configuration of the sensor unit 24 included in the base station 20. For example, the sensor unit 34 may be an RF sensor or a non-RF sensor. Furthermore, the sensor unit 34 may be a sensor system that combines an RF sensor and a non-RF sensor.

[0109] The surface unit 35 is a structure that reflects or transmits the incoming radio waves. For example, the surface unit 35 is a reflector formed of a metasurface (metasurface element) whose permittivity and / or permeability can be dynamically controlled. The surface unit 35 may be a transmission plate configured to transmit the incoming radio waves and capable of controlling the refractive index, etc., of the transmitted radio waves. The transmission path control device 30 is not limited to a plate-like shape. For example, the transmission path control device 30 may be a sheet-like shape. A metasurface element is a type of artificial medium (metamaterial) that realizes desired characteristics (e.g., permittivity, permeability, etc.) by periodically arranging structures that are small relative to the wavelength. The control unit 33 can control, for example, the amplitude, phase, polarization, or frequency of the incoming radio waves by manipulating the characteristics (e.g., reflection characteristics or transmission characteristics) of the metasurface provided by the surface unit 35. The structure provided by the transmission path control device 30 is not limited to a surface-like shape. The surface unit 35 mentioned in the following description can be rephrased as a metamaterial unit 35, a material unit 35, etc.

[0110] FIG. 8 is a diagram showing an example of the configuration of the surface unit 35 included in the transmission path control device 30. The surface unit 35 includes a plurality of elements 351 that can change the characteristics related to the reflection or transmission of the incoming radio wave. The elements 351 are, for example, metasurface elements. In the example of FIG. 8, the surface unit 35 includes m×n elements 351 (elements 351 １１ ~Element 351 ｍｎ ) are provided. As shown in FIG. 8 , for example, two or more of the elements 351 are each provided with a channel estimation unit 353 in addition to a phase shifter 352 that manipulates reflected waves / transmitted waves. The transmission path control device 30 can switch the circuit connected to the two or more elements 351 from the phase shifter 352 to the channel estimation unit 353. The elements 351 on which the channel estimation unit 353 is provided may be all of the multiple elements 351 provided in the surface unit 35, or may be some of the multiple elements 351. A secondary modulation unit, an amplifier, etc. may be additionally provided in the phase shifter 352.

[0111] 2-4. Configuration of Terminal Device Next, the configuration of the terminal device 40 will be described.

[0112] The terminal device 40 is a wireless communication device that performs wireless communication with other wireless communication devices (e.g., a base station 20 or another terminal device 40). Any type of information processing device (computer) can be used as the terminal device 40. For example, the terminal device 40 may be a mobile terminal such as a mobile phone, a smart device (smartphone or tablet), a personal digital assistant (PDA), or a notebook PC. The terminal device 40 may also be an imaging device (e.g., a camcorder) equipped with a communication function. The terminal device 40 may also be a motorcycle or a mobile broadcast vehicle equipped with a communication device such as a field pickup unit (FPU). The terminal device 40 may also be an M2M (Machine to Machine) device or an IoT (Internet of Things) device. The terminal device 40 may also be a wearable device such as a smartwatch.

[0113] Furthermore, the terminal device 40 may be an xR device such as an AR (Augmented Reality) device, a VR (Virtual Reality) device, or an MR (Mixed Reality) device. In this case, the xR device may be a glasses-type device such as AR glasses or MR glasses, or a head-mounted device such as a VR head-mounted display. When the terminal device 40 is an xR device, the terminal device 40 may be a standalone device consisting only of a part worn by a user (e.g., a glasses part). Furthermore, the terminal device 40 may be a terminal-linked device consisting of a part worn by a user (e.g., a glasses part) and a terminal part (e.g., a smart device) linked to the part worn by a user.

[0114] The terminal device 40 may be capable of NOMA communication with the base station 20. The terminal device 40 may be able to use an automatic repeat technique such as HARQ when communicating with the base station 20. The terminal device 40 may be capable of sidelink communication with another terminal device 40. The terminal device 40 may be able to use an automatic repeat technique such as HARQ when performing sidelink communication. The terminal device 40 may be capable of NOMA communication when performing sidelink communication with another terminal device 40. The terminal device 40 may be capable of LPWA communication with other wireless communication devices such as the base station 20. The wireless communication used by the terminal device 40 may be wireless communication using millimeter waves. The wireless communication used by the terminal device 40, including sidelink communication, may be wireless communication using radio waves, or wireless communication using infrared or visible light, i.e., optical wireless.

[0115] The terminal device 40 may be a mobile wireless communication device, i.e., a mobile device. The terminal device 40 may be a wireless communication device installed in a mobile device, or may be the mobile device itself. The terminal device 40 may be a vehicle that moves on a road, such as an automobile, bus, truck, or motorcycle, or may be a wireless communication device mounted on the vehicle. The mobile device may be a mobile terminal, or may be a mobile device that moves on land (in the narrow sense of the word), underground, on water, or underwater. The mobile device may also be a mobile device that moves within the atmosphere, such as an airplane, airship, balloon, or helicopter, or a mobile device that moves outside the atmosphere, such as an artificial satellite. The mobile device may also be a UAV (Unmanned Aerial Vehicle) such as a drone. The terminal device 40 may also be a wireless communication device mounted on the mobile device.

[0116] The terminal device 40 may be capable of simultaneously connecting to and communicating with a plurality of base stations 20 or a plurality of cells. When one base station 20 supports a communication area through a plurality of cells (e.g., pCell or sCell), the plurality of cells can be bundled together to enable communication between the base station 20 and the terminal device 40 by using carrier aggregation (CA) technology, dual connectivity (DC) technology, multi-connectivity (MC) technology, or the like. Alternatively, communication between the terminal device 40 and the plurality of base stations 20 can also be performed via cells of different base stations 20 by coordinated multi-point transmission and reception (CoMP) technology.

[0117] The terminal device 40 may be a relay terminal that relays communications to a remote terminal.

[0118] Fig. 9 is a diagram showing the configuration of a terminal device 40 according to this embodiment. The terminal device 40 includes a wireless communication unit 41, a storage unit 42, a control unit 43, and a sensor unit 44. The terminal device 40 does not necessarily have to include all of these components. For example, the terminal device 40 does not necessarily have to include the sensor unit 44. Note that the configuration shown in Fig. 9 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the terminal device 40 may be distributed and implemented across multiple physically separated components.

[0119] The wireless communication unit 41 is a signal processing unit for wireless communication with other wireless communication devices (for example, the base station 20 or other terminal devices 40). The wireless communication unit 41 is controlled by the control unit 43. The wireless communication unit 41 supports one or more wireless access methods. The wireless communication unit 41 may support at least one of NR, LTE, and 6G. In addition to NR, LTE, and 6G, the wireless communication unit 41 may also support W-CDMA, cdma2000, and the like. The wireless communication unit 41 may also support automatic retransmission techniques such as HARQ (Hybrid Automatic Repeat reQuest).

[0120] The wireless communication unit 41 includes a transmission processing unit 411, a reception processing unit 412, and an antenna 413. The wireless communication unit 41 may include multiple transmission processing units 411, multiple reception processing units 412, and multiple antennas 413. If the wireless communication unit 41 supports multiple wireless access methods, each unit of the wireless communication unit 41 may be configured separately for each wireless access method. The transmission processing unit 411 and the reception processing unit 412 may be configured separately for LTE, NR, and 6G. The antenna 413 may be configured with multiple antenna elements, for example, multiple patch antennas. The wireless communication unit 41 may have a beamforming function. For example, the wireless communication unit 41 may have a polarization beamforming function using vertical polarization (V polarization) and horizontal polarization (H polarization) (or a polarization beamforming function using dual polarization in polarization directions 45 degrees and -45 degrees from the vertical direction).

[0121] The storage unit 42 is a readable and writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 42 functions as a storage means of the terminal device 40.

[0122] The control unit 43 is a controller that controls each unit of the terminal device 40. The control unit 43 controls the wireless communication unit to perform wireless communication with other wireless communication devices (e.g., the base station 20 or another terminal device 40). The control unit 43 may be implemented by a processor such as a CPU or an MPU. In particular, the control unit 23 may be implemented by a processor executing various programs stored in a storage device internal to the terminal device 40 using RAM or the like as a work area. The control unit 43 may be implemented by an integrated circuit such as an ASIC or an FPGA. The control unit 43 may be implemented by a GPU. A CPU, an MPU, an ASIC, an FPGA, and a GPU can all be considered controllers. The control unit 43 may be composed of multiple physically separated objects. For example, the control unit 43 may be composed of multiple semiconductor chips.

[0123] The control unit 43 includes an acquisition unit 431, a transmission unit 432, and a communication control unit 433. Each block (acquisition unit 431 to communication control unit 433) constituting the control unit 43 is a functional block that indicates the function of the control unit 43. These functional blocks may be software blocks or hardware blocks. For example, each of the above-mentioned functional blocks may be a software module realized by software (including a microprogram), or may be a circuit block on a semiconductor chip (die). Of course, each functional block may be a processor or an integrated circuit. The control unit 43 may be configured with functional units different from the above-mentioned functional blocks. The method of configuring the functional blocks is arbitrary.

[0124] The operation of each block constituting the control unit 43 may be similar to that of each block provided in the control unit 23 of the base station 20. The operation of the control unit 23 may be similar to that of the control unit 13 of the management device 10.

[0125] The sensor unit 44 is a sensor that acquires various information related to wireless communication. For example, the sensor unit 44 is a sensor that acquires information about objects around the device. For example, the sensor unit 44 is a sensor that acquires information about the position, shape, movement, etc. of other objects. The sensor unit 44 may be a sensor that detects the state of the device itself (for example, the position, movement speed, tilt, vibration, rotation, etc. of the terminal device 40). Alternatively, the configuration of the sensor unit 44 may be the same as the configuration of the sensor unit 24 included in the base station 20. For example, the sensor unit 44 may be an RF sensor or a non-RF sensor. Furthermore, the sensor unit 44 may be a sensor system that combines an RF sensor and a non-RF sensor.

[0126] <<3. Operation of the Communication System>> The configuration of the communication system 1 has been described above. Next, the operation of the communication system 1 of this embodiment will be described.

[0127] As described above, in the conventional RIS, a communication unit included in the RIS performs an operation for channel estimation (e.g., a sounding operation). However, in this conventional channel estimation method, depending on the RIS (e.g., depending on the shape / size of the RIS), the actual channel state and the channel estimation result may differ from each other.

[0128] The transmission path control device 30 (e.g., RIS) of this embodiment includes a surface unit 35 composed of a plurality of elements 351 capable of changing the characteristics related to the reflection or transmission of incoming radio waves. In the transmission path control device 30 of this embodiment, a channel estimation unit 353 is arranged in each of two or more of the plurality of elements 351, in addition to a phase shifter 352 that controls the reflected wave / transmitted wave. The channel estimation unit 353 may be arranged in all of the plurality of elements 351, or in some of the plurality of elements 351. The transmission path control device 30 acquires information (hereinafter referred to as channel information) related to the results of channel estimation in each of the two or more elements 351 based on information from the channel estimation units 353. The transmission path control device 30 transmits this channel information to a communication device (e.g., a base station 20 and / or a terminal device 40). The communication device performs processing related to communication between the communication devices based on the channel information.

[0129] The above process (hereinafter referred to as channel estimation process) will be described below with reference to the drawings.

[0130] <3-1. Channel Estimation Processing> FIG. 10 is a flowchart showing the channel estimation processing of this embodiment.

[0131] A communication device (for example, the base station 20 and / or the terminal device 40) requests capability information related to the channel estimation unit 353 from the transmission path control device 30 (step S101). The transmission path control device 30 transmits the capability information to the communication device (step S102).

[0132] Next, the communication device causes the transmission path control device 30 to execute a channel information acquisition operation in order to acquire channel information between the communication device and the transmission path control device 30. Specifically, the communication device transmits a signal (hereinafter referred to as a trigger signal) that triggers a channel estimation operation to the transmission path control device 30 (step S103). The communication device may store information regarding the channel estimation mode (hereinafter referred to as channel estimation mode information) in this trigger signal. The channel estimation mode information may be composed of one or more pieces of information that specify the mode of channel estimation by the transmission path control device 30. The communication device may determine the information (channel estimation mode) to be stored in this channel estimation mode information based on the capability information acquired in step S102.

[0133] The receiving unit 334 of the transmission path control device 30 receives a trigger signal from the communication device. This trigger signal includes channel estimation mode information. The channel estimation mode information will be described later.

[0134] Then, the communication device transmits a signal for channel estimation to the transmission path control device 30 (step S104). Examples of the channel estimation signal include a CSI-RS (Channel State Information-Reference Signal), an SRS (Sounding Reference Signal), or a CSI Report. The communication device may store channel estimation mode information in these signals. Furthermore, the communication device may use a new signal that stores the channel estimation mode information as the channel estimation signal to be transmitted to the transmission path control device 30.

[0135] The channel estimation control unit 333 of the transmission path control device 30 controls the operation of the multiple channel estimation units 353 based on channel estimation mode information. For example, the transmission path control device 30 controls the operation of the multiple channel estimation units 353 so as to achieve a channel estimation mode specified by the communication device. For example, upon receiving a trigger signal, the transmission path control device 30 switches the circuits connected to two or more elements 351 in which the channel estimation units 353 are arranged from the phase shifter 352 to the channel estimation units 353. At this time, the channel estimation control unit 333 may determine the element 351 whose connection circuit is to be switched to the channel estimation unit 353 based on the channel estimation mode information. Of course, the channel estimation control unit 333 may also control the operation of the channel estimation unit 353 so as to achieve a predetermined channel estimation mode. Then, the multiple channel estimation units 353 each perform an operation related to channel estimation based on a channel estimation signal transmitted from the communication device.

[0136] The acquisition unit 331 of the transmission path control device 30 acquires information on the results of channel estimation from the multiple channel estimators 353. Then, the transmission unit 332 of the transmission path control device 30 transmits channel information based on the information on the results of channel estimation to the communication device (step S105). Here, the channel information may be information that integrates the channel estimation results of two or more elements 351.

[0137] The communication device acquires channel information from the transmission path control device 30. Then, the communication device performs various controls based on the channel information. For example, the base station 20 performs communication control of the base station 20 and / or the terminal device 40 based on the channel information. For example, the base station 20 determines communication settings (communication parameters) to be used by the base station 20 and / or the terminal device 40 based on the channel information. The base station 20 and / or the terminal device 40 communicate using the communication settings (communication parameters) determined based on the channel information.

[0138] This enables more accurate channel estimation, enabling communication devices (e.g., the base station 20 and / or the terminal device 40) to perform high-quality communication via the transmission path control device 30. As a result, radio wave resources can be used more efficiently.

[0139] <3-2. Capability Information> The transmission path control process has been outlined above, and next, capability information will be described.

[0140] As described above, the transmission path control device 30 transmits capability information to the communication device (step S102). The capability information is capability information related to channel estimation by the transmission path control device 30 (e.g., RIS). This capability information is signaled in advance between the communication device and the transmission path control device 30 before the channel estimation operation. The communication device (e.g., base station 20 and / or terminal device 40) determines the element 351 (e.g., metasurface element) to be used for channel estimation in accordance with the accuracy of the beam used during communication using the RIS and the form of channel estimation.

[0141] Here, it is assumed that the transmission path control device 30 (or the surface unit 35 provided in the transmission path control device 30) is the RIS. In this case, the capability information may include at least one of the pieces of information shown in (A1) to (A9) below. Of course, the information included in the capability information is not limited to the information shown in (A1) to (A9) below. Note that the description of RIS shown below can be replaced with the transmission path control device 30 or the surface unit 35.

[0142] (A1) Information about the size of the RIS Information about the size of the RIS is information that specifically indicates the size of the RIS (for example, the transmission path control device 30, or the surface unit 35 provided in the transmission path control device 30). For example, the information about the size of the RIS may be at least one of the pieces of information shown in the following (A1-1) to (A1-3). (A1-1) Information that numerically indicates the size of the RIS. (A1-2) Information that indicates to which size category the size of the RIS belongs, defined in advance by standardization specifications, etc. (A1-3) Information about the effective area of ​​the RIS with respect to a communication device (for example, the base station 20 and / or the terminal device 40).

[0143] (A2) Information on the size of element 351 Information on the size of element 351 is information that specifically indicates the size of element 351 (for example, metasurface element) included in the RIS. For example, information on the size of the RIS may be at least one of the pieces of information shown in (A2-1) to (A2-2) below. (A2-1) Information that numerically indicates the size of element 351. (A2-2) Information that indicates to which size category the size of element 351 belongs, defined in advance by standardization standards, etc.

[0144] (A3) Information on the arrangement of elements 351 The information on the arrangement of elements 351 is information indicating the arrangement of elements 351 (e.g., metasurface elements). Examples of the information on the arrangement of elements 351 include at least one of information indicating the arrangement interval of elements 351 and information indicating the area ratio of elements 351 to the area of ​​RIS.

[0145] (A4) Information on the Function of Each Element 351 The information on the function of each element 351 is information on the function for controlling the reflected wave / transmitted wave for each element 351 (e.g., metasurface element). Examples of the function for controlling the reflected wave / transmitted wave include at least one of the phase shifter 352, the amplifier, the secondary modulation unit, and the channel estimation unit 353.

[0146] (A5) Information Regarding Control Precision of Element 351 Information regarding control precision of element 351 is, for example, information indicating the controllable granularity for each of the above-mentioned functions (functions of each element 351).

[0147] (A6) Information on the form of channel estimation The information on the form of channel estimation is information indicating which form the RIS can support among a plurality of forms of channel estimation including the operation of this embodiment (for example, forms of channel estimation defined in advance by standardization specifications, etc.). The information on the form of channel estimation may include at least one of information on the mapping pattern of the element 351 (for example, metasurface element) having the channel estimation unit 353, and information on whether each element 351 (for example, metasurface element) has the channel estimation unit 353.

[0148] (A7) Identification Information for Each Element 351 The identification information for each element 351 is information (e.g., ID information) used by the communication device to identify the target element 351 from multiple elements 351 when specifying the operation of the element 351 (e.g., metasurface element). Note that the capability information may include, apart from the identification information for each element 351, at least one of information regarding the element 351, information regarding the mapping pattern of the element 351 (e.g., metasurface element) that has the channel estimation unit 353, and information regarding whether each element 351 (e.g., metasurface element) has the channel estimation unit 353.

[0149] (A8) Information on the format of the channel estimation result Information on the format of the channel estimation result is information indicating which of multiple feedback formats of the channel estimation result the RIS (e.g., the transmission path control device 30) supports.

[0150] (A9) Identification Information of RIS The identification information of the RIS is information (for example, ID information) that allows the communication device to identify the RIS.

[0151] <3-3. Channel Estimation Mode Information> Next, the channel estimation mode information will be described.

[0152] As described above, the communication device transmits channel estimation mode information to the transmission path control device 30 (e.g., RIS). In the above-described channel estimation process, the channel estimation mode information is stored in a trigger signal and transmitted (step S103). The channel estimation mode information is composed of, for example, one or more pieces of information specifying the mode of channel estimation of the transmission path control device 30.

[0153] Here, it is assumed that the transmission path control device 30 (or the surface unit 35 included in the transmission path control device 30) is the RIS. In this case, the channel estimation mode information may include at least one of the pieces of information shown in the following (B1) to (B4). Of course, the information included in the channel estimation mode information is not limited to the information shown in the following (B1) to (B4). The operation of the communication system 1 in each of the cases (B1) to (B4) will be described in detail in Examples 1 to 4 described later. Note that the description of RIS shown below can be replaced with the transmission path control device 30 or the surface unit 35.

[0154] (B1) A form in which only channel estimation is performed at a single frequency. (B2) A form in which channels of different frequency bands are simultaneously estimated. (B3) A form in which channels are simultaneously estimated between the RIS and the base station 20 and between the RIS and the terminal device 40. (B4) A form in which other signals are reflected / transmitted at the same time as channel estimation.

[0155] The channel estimation form information may be information that specifically indicates a form of channel estimation defined in a standard specification or the like. The channel estimation form information may also be information that specifies the allocation of operations related to channel estimation for each element 351 (e.g., metasurface element). This also allows the communication device to indirectly specify the form of channel estimation.

[0156] The information specifying the allocation of operations related to channel estimation may be information specifying an element 351 to be used during channel estimation (hereinafter referred to as element specification information). The element specification information is information for specifying which of the multiple elements 351 the RIS is to use the channel estimation unit 353 of.

[0157] The element designation information may include at least one of the pieces of information shown in the following (C1) to (C9). Of course, the information included in the element designation information is not limited to the pieces of information shown in the following (C1) to (C9). Note that the description of the RIS shown below can be replaced with the transmission path control device 30 or the surface unit 35.

[0158] (C1) Mapping pattern designation information of the element 351 used for channel estimation (e.g., information on a mapping pattern selected from a plurality of mapping patterns specifically defined in a standardized specification or the like) (C2) Mapping pattern designation information determined based on capability information related to channel estimation of the RIS (e.g., information on a mapping pattern selected from a plurality of mapping patterns predefined between the RIS and the communication device) (C3) Mapping pattern designation information determined based on implementation (C4) Designation information for each element 351 as to whether to perform channel estimation (C5) Designation information for each element 351 as to whether to use a predetermined function (e.g., a band-limiting filter) (C6) Information on the number of elements used for channel estimation per unit area (C7) Information on the number of elements used for channel estimation out of the number of all elements 351 (C8) Information on the ratio of the number of elements used for channel estimation out of the number of all elements 351 (C9) Information designating whether to perform channel estimation, the channel estimation unit 353 or the communication unit 31 (e.g., information designating whether to perform channel estimation on an element-by-element basis or on an RIS-by-RIS basis)

[0159] In addition, when a communication device specifies a mapping pattern to be used by the RIS from among multiple mapping patterns predefined between the RIS and the communication device, information on the mapping pattern is signaled in advance between the RIS and the communication device (for example, between the RIS and the base station 20, and / or between the RIS and the terminal device 40).

[0160] <3-4. Channel Information> Next, the channel information will be described.

[0161] The transmission path control device 30 (e.g., RIS) feeds back channel information based on information on the result of channel estimation to the communication device (step S105). Here, the information on the result of channel estimation from the transmission path control device 30 may be information on an element 351 (e.g., metasurface element) basis. Also, the information on the result of channel estimation may be information in a format that allows identification of the correspondence between the element 351 and the result of channel estimation. The transmission path control device 30 may feed back the result of channel estimation to the communication device (e.g., base station 20 and / or terminal device 40) based on the element designation information.

[0162] When only a specific element 351 has a channel estimation unit 353, the transmission path control device 30 may estimate and interpolate the channel estimation results of the other elements 351 based on the channel estimation result of the specific element 351. For example, the interpolation unit 335 of the transmission path control device 30 may interpolate the channel estimation results of elements 351 for which no channel estimation results have been obtained, based on the channel estimation results of elements 351 for which channel estimation results have been obtained. Then, the transmission unit 332 of the transmission path control device 30 may transmit channel information based on the multiple channel estimation results, including the interpolated channel estimation result, to the communication device. The transmission path control device 30 may perform this interpolation processing only when specified by the communication device. This allows the transmission path control device 30 to improve the accuracy of channel estimation.

[0163] Furthermore, the transmission path control device 30 may transmit, as channel information, information that integrates the channel estimation results of the plurality of elements 351 to the communication device. The transmission path control device 30 may feed back this integrated information as the channel estimation result of the representative element 351. This allows the transmission path control device 30 to reduce the amount of information that is fed back.

[0164] Furthermore, the transmission path control device 30 may transmit, as channel information, information on the difference between the channel estimation result of a specific element 351 and the channel estimation results of other elements 351 to the communication device. For example, the transmission path control device 30 may transmit, as channel information, information indicating the channel estimation result of one element 351 of the multiple elements 351 and information on the channel estimation results of other elements 351 of the multiple elements 351, which is expressed as the difference between the channel estimation result of the one element 351. This also enables the transmission path control device 30 to reduce the amount of feedback information.

[0165] <3-5. Method of Using Channel Information> Next, a method of using the channel information obtained by the above-described channel estimation process will be described.

[0166] The communication device acquires channel information from the transmission path control device 30 (e.g., RIS). Then, the communication device (e.g., base station 20 and / or terminal device 40) performs various controls based on the channel information. For example, the communication device uses the acquired channel information to determine the control method for each element 351, the form of the beam to be transmitted by the communication device, and the antenna port to be used. Note that if the communication device does not obtain channel estimation results for all elements 351 (e.g., if only a specific element 351 of the transmission path control device 30 has a channel estimation unit 353), the communication device may use the channel estimation result of the specific element 351 to interpolate the channel information of the other elements 351.

[0167] <<4. Example>> The operation of the communication system 1 has been described above. Next, an example of the above-mentioned channel estimation process will be described.

[0168] In the following embodiment, a communication environment is assumed in which a base station 20 and a terminal device 40 communicate with each other. In this communication environment, one or more RISs are installed as a transmission path control device 30. In the following description, these multiple RISs may be referred to as RIS#1 to RIS#N, where N is an arbitrary integer. Note that the RISs appearing in the following description can be replaced with a transmission path control device 30 other than a RIS.

[0169] As described above, the RIS performs processing related to channel estimation of this embodiment based on channel estimation form information from the communication device (base station 20 and / or terminal device 40). The form of channel estimation by this RIS can be divided into, for example, the forms shown in (B1) to (B4) below.

[0170] (B1) A form in which only channel estimation is performed at a single frequency. (B2) A form in which channels of different frequency bands are simultaneously estimated. (B3) A form in which channels are simultaneously estimated between the RIS and the base station 20 and between the RIS and the terminal device 40. (B4) A form in which other signals are reflected / transmitted at the same time as channel estimation.

[0171] Examples (B1) to (B4) will be described below.

[0172] 4-1. Example 1 In Example 1, a case will be described in which the RIS performs channel estimation only at a single frequency. Example 1 is an example of the form shown in (B1) above.

[0173] 11 is a sequence diagram illustrating a channel estimation process according to the first embodiment. Hereinafter, the channel estimation process according to the first embodiment will be described with reference to FIG.

[0174] The base station 20 or the terminal device 40 requests capability information related to channel estimation of the RIS from the RIS (step S201). The RIS transmits the capability information to the base station 20 or the terminal device 40 (step S202).

[0175] The acquisition unit 231 of the base station 20 or the acquisition unit 431 of the terminal device 40 acquires capability information from the RIS. The base station 20 or the terminal device 40 transmits a trigger signal to the RIS to trigger a channel estimation operation (step S203). The base station 20 or the terminal device 40 stores channel estimation mode information in this trigger signal. The base station 20 or the terminal device 40 may determine the information (channel estimation mode) to be stored in this channel estimation mode information based on the capability information acquired in step S202.

[0176] The RIS receives a trigger signal from the base station 20 or the terminal device 40. This trigger signal includes channel estimation mode information. In the first embodiment, it is assumed that the mode shown in (B1) above is specified as the channel estimation mode.

[0177] The transmitter 232 of the base station 20 or the transmitter 432 of the terminal device 40 transmits a signal for channel estimation to the RIS (step S204). Examples of the channel estimation signal include a CSI-RS (Channel State Information-Reference Signal), an SRS (Sounding Reference Signal), or a CSI Report. The communication device may store channel estimation mode information in these signals. Alternatively, the communication device may use a new signal that stores the channel estimation mode information as the channel estimation signal to be transmitted to the RIS.

[0178] The RIS controls the operation of the plurality of channel estimation units 353 so as to achieve a channel estimation mode specified by the communication device. For example, upon receiving a trigger signal, the RIS switches the circuits connected to two or more elements 351 in which the channel estimation units 353 are arranged from the phase shifter 352 to the channel estimation units 353. At this time, the channel estimation control unit 333 may determine the element 351 whose connection circuit is to be switched to the channel estimation unit 353 based on the channel estimation mode information. Then, the plurality of channel estimation units 353 each perform an operation related to channel estimation based on a channel estimation signal transmitted from the communication device.

[0179] FIG. 12 is a diagram illustrating an example of the operation of the RIS. Specifically, FIG. 12 is a diagram illustrating an example of the operation of the RIS when elements 351 that perform channel estimation and elements 351 that do not perform channel estimation are alternately arranged. In the example of FIG. 12, the elements 351 that do not perform channel estimation are positioned so that they are sandwiched on all four sides by elements 351 that perform channel estimation. The elements 351 that perform channel estimation are, for example, elements 351 connected to a channel estimation unit 353. The elements 351 that do not perform channel estimation are elements 351 connected to a phase shifter 352. The elements 351 that do not perform channel estimation may be elements 351 in which a channel estimation unit 353 is not arranged, as a connectable circuit (switchable circuit).

[0180] The channel estimation unit 353 of an element 351 that does not perform channel estimation may calculate its own channel estimation result based on the channel estimation results of surrounding elements 351 that perform channel estimation. In this case, the channel estimation unit 353 may use the average of the channel estimation results of the surrounding elements 351 as its own channel estimation result. Alternatively, the channel estimation unit 353 may use the channel estimation result of a specific element 351 as its own channel estimation result. Of course, the channel estimation unit 353 may calculate the channel estimation result based on a specific calculation formula.

[0181] The channel estimation control unit 333 of the RIS may calculate the channel estimation result of the element 351 that does not perform channel estimation based on the channel estimation results of the elements 351 located around the element 351 that does not perform channel estimation. In this case, the channel estimation control unit 333 may take the average of the channel estimation results of the elements 351 located around the element 351 that does not perform channel estimation as the channel estimation result of the element 351 that does not perform channel estimation. Furthermore, the channel estimation control unit 333 may use the channel estimation result of a specific element 351 as the channel estimation result of the element 351 that does not perform channel estimation. Of course, the channel estimation unit 353 may calculate the channel estimation result based on a specific calculation formula.

[0182] 11 , the RIS acquires channel estimation results from the plurality of elements 351. Then, the RIS generates channel information based on the acquired channel estimation results. Here, the channel information may be information that integrates the channel estimation results from each of the plurality of elements 351. Then, the RIS transmits the channel information to the base station 20 or the terminal device 40 (step S205).

[0183] The base station 20 or the terminal device 40 acquires the channel information from the RIS, and then performs various processes related to communication based on the channel information.

[0184] <4-2. Example 2> Example 2 describes a case where the RIS simultaneously estimates channels for different frequency bands. Example 2 is an example of the form shown in (B2) above. In Example 2, the RIS includes a surface portion 35 (plurality of elements 351) that can simultaneously reflect / transmit radio waves of multiple frequency bands.

[0185] 13 is a sequence diagram illustrating a channel estimation process according to the second embodiment. Hereinafter, the channel estimation process according to the second embodiment will be described with reference to FIG.

[0186] The base station 20 or the terminal device 40 requests capability information related to channel estimation of the RIS from the RIS (step S301). The RIS transmits the capability information to the base station 20 or the terminal device 40 (step S302).

[0187] The acquisition unit 231 of the base station 20 or the acquisition unit 431 of the terminal device 40 acquires capability information from the RIS. The base station 20 or the terminal device 40 transmits a trigger signal to the RIS to trigger a channel estimation operation (step S303). The base station 20 or the terminal device 40 stores channel estimation mode information in this trigger signal. The base station 20 or the terminal device 40 may determine the information (channel estimation mode) to store in this channel estimation mode information based on the capability information acquired in step S302.

[0188] The RIS receives a trigger signal from the base station 20 or the terminal device 40. This trigger signal includes channel estimation mode information. In the second embodiment, it is assumed that the mode shown in (B2) above is specified as the channel estimation mode. The RIS controls the operation of the multiple channel estimation units 353 so as to achieve the channel estimation mode specified by the communication device. For example, upon receiving the trigger signal, the RIS switches the circuit connected to the element 351 in which the channel estimation unit 353 is arranged based on the channel estimation mode information.

[0189] The transmitter 232 of the base station 20 or the transmitter 432 of the terminal device 40 transmits a channel estimation signal for frequency band #1 to the RIS (step S304). The multiple channel estimation units 353 included in the RIS each perform channel estimation operations based on the channel estimation signal for frequency band #1. The RIS acquires channel estimation results from the multiple elements 351. The RIS then generates channel information for frequency band #1 based on the acquired channel estimation results. The RIS then transmits the channel information for frequency band #1 to the base station 20 or the terminal device 40 (step S305).

[0190] The transmitter 232 of the base station 20 or the transmitter 432 of the terminal device 40 transmits a channel estimation signal for frequency band #2 to the RIS (step S306). The multiple channel estimation units 353 included in the RIS each perform channel estimation operations based on the channel estimation signal for frequency band #2. The RIS acquires channel estimation results from the multiple elements 351. The RIS then generates channel information for frequency band #2 based on the acquired channel estimation results. The RIS then transmits the channel information for frequency band #2 to the base station 20 or the terminal device 40 (step S307).

[0191] The frequency bands involved in the channel estimation process are not limited to frequency band #1 and frequency band #2. The base station 20 or the terminal device 40 may transmit channel estimation signals for more than two frequency bands. The RIS may also perform operations related to channel estimation for more than two frequency bands.

[0192] The RIS may feed back channel estimation results of a plurality of frequency bands in one channel information (or one signal) to the base station 20 or the terminal device 40. When there is similarity between the channels, the RIS may feed back, as channel information, first information that is the channel estimation result of one frequency band and second information that is the channel estimation result of another frequency band and is difference information between the first information and the first information to the base station 20 or the terminal device 40.

[0193] The base station 20 or the terminal device 40 acquires the channel information from the RIS, and then performs various processes related to communication based on the channel information.

[0194] 14 is a diagram illustrating a configuration example of the RIS (transmission path control device 30) according to the second embodiment. When frequency bands for which channels are simultaneously estimated in the RIS are close to each other, one or more band-limiting filters (frequency filters #1 to #N in the example of FIG. 14) may be provided before the phase shifter 352 and the channel estimation unit 353. The introduction of the band-limiting filters can prevent mutual channel estimation signals from interfering with other frequency bands.

[0195] <4-2-3. Example of RIS Operation> An example of RIS operation when simultaneously estimating channels in different frequency bands is shown below. Figures 15 to 17 are diagrams for explaining an example of RIS operation when simultaneously estimating channels in two different frequency bands (frequency band #1 and frequency band #2).

[0196] (Operation Example 1) Figure 15 shows an example of the operation of the RIS when elements 351 performing channel estimation for frequency band #1 and elements 351 performing channel estimation for frequency band #2 are alternately arranged. In the example of Figure 15, the elements 351 not performing channel estimation for frequency band #1 are positioned so that they are sandwiched on all sides by elements 351 performing channel estimation for frequency band #1. The channel estimation unit 353 of the elements 351 not performing channel estimation for frequency band #1 may calculate its own channel estimation result based on the channel estimation results of the surrounding elements 351 performing channel estimation for frequency band #1. In this case, the channel estimation unit 353 may average the channel estimation results of the surrounding elements 351 as its own channel estimation result. Alternatively, the channel estimation unit 353 may use the channel estimation result of a specific element 351 as its own channel estimation result. Of course, the channel estimation unit 353 may calculate the channel estimation result based on a specific calculation formula. The channel estimation result interpolation may be performed by the channel estimation control unit 333 rather than the channel estimation unit 353. Furthermore, the interpolation of the channel estimation results may be performed by the base station 20 and / or the terminal device 40. The channel estimation results for frequency band #2 can also be obtained by similar processing.

[0197] (Operation Example 2) Figure 16 is a diagram showing an example of operation of the RIS when elements 351 performing channel estimation for frequency band #1 and elements 351 performing channel estimation for frequency band #2 are each arranged in half of the RIS. In the example of Figure 16, elements 351 performing channel estimation for frequency band #1 and elements 351 performing channel estimation for frequency band #2 are arranged in the left and right halves of the RIS, respectively. However, they may also be arranged in the top and bottom halves, or in diagonal halves. In the example of Figure 16, the RIS may generate channel information for frequency band #1 based on the channel estimation result of element 351 performing channel estimation for frequency band #1. Furthermore, the RIS may generate channel information for frequency band #2 based on the channel estimation result of element 351 performing channel estimation for frequency band #2, for example.

[0198] (Operation Example 3) FIG. 17 illustrates an example of operation of the RIS when the elements 351 performing channel estimation for frequency band #1 and the elements 351 performing channel estimation for frequency band #2 are arranged at different ratios. The RIS may change this ratio according to predetermined conditions. For example, the RIS may change this ratio based on the ratio of the number of elements 351 used for reflection / transmission for each frequency band and / or the required channel estimation accuracy. The RIS may acquire information on the conditions for determining the ratio (or information on the ratio itself) from the base station 20 and / or the terminal device 40. This information may be included in the channel estimation mode information. In the example of FIG. 17 , the RIS may generate channel information for frequency band #1 based on the channel estimation result of the element 351 performing channel estimation for frequency band #1. Furthermore, the RIS may generate channel information for frequency band #2 based on the channel estimation result of the element 351 performing channel estimation for frequency band #2.

[0199] In the above three examples, channel estimation is performed in all elements 351, but the multiple elements 351 included in the RIS may include elements 351 that do not perform channel estimation.

[0200] <4-3. Example 3> Example 3 describes a case where the RIS simultaneously estimates channels between the RIS and the base station 20 and between the RIS and the terminal device 40. Example 3 is an example of the form shown in (B3) above.

[0201] 18 is a sequence diagram illustrating a channel estimation process according to the third embodiment. Hereinafter, the channel estimation process according to the third embodiment will be described with reference to FIG.

[0202] The base station 20 requests capability information related to channel estimation of the RIS from the RIS (step S401). The RIS transmits the capability information to the base station 20 (step S402). In the example of Fig. 18, the base station 20 requests the RIS to transmit the capability information, but the terminal device 40 may also request the RIS to transmit the capability information. In this case, the RIS may transmit the capability information to the terminal device 40.

[0203] The acquisition unit 231 of the base station 20 or the acquisition unit 431 of the terminal device 40 acquires capability information from the RIS. The base station 20 or the terminal device 40 transmits a trigger signal to the RIS to trigger a channel estimation operation (step S403). Note that the acquisition unit 431 of the terminal device 40 may acquire the capability information from the RIS. Then, the terminal device 40 may transmit a trigger signal to the RIS. The base station 20 or the terminal device 40 stores channel estimation mode information in this trigger signal. The base station 20 or the terminal device 40 may determine the information (channel estimation mode) to be stored in this channel estimation mode information based on the capability information acquired in step S402.

[0204] The RIS receives a trigger signal from the base station 20 or the terminal device 40. This trigger signal includes channel estimation mode information. In the third embodiment, it is assumed that the mode shown in (B3) above is specified as the channel estimation mode. The RIS controls the operation of the multiple channel estimation units 353 so as to achieve the channel estimation mode specified by the communication device. For example, upon receiving the trigger signal, the RIS switches the circuit connected to the element 351 in which the channel estimation unit 353 is arranged based on the channel estimation mode information.

[0205] The transmitter 232 of the base station 20 transmits a channel estimation signal to the RIS (step S404a). Also, the transmitter 432 of the terminal device 40 transmits a channel estimation signal to the RIS (step S404b). At this time, the base station 20 and the terminal device 40 transmit the channel estimation signal (for example, CSI-RS or SRS) in a form that allows the RIS side to distinguish between a channel estimation signal between the RIS and the base station 20 and a channel estimation signal between the RIS and the terminal device 40.

[0206] For example, the base station 20 may use half of the radio resources used for CSI-RS as a signal for channel estimation between the RIS and the base station 20, and the terminal device 40 may use the remaining half as a signal for channel estimation between the RIS and the terminal device 40. In this case, the radio resources for channel estimation between the RIS and the base station 20 and the radio resources for channel estimation between the RIS and the terminal device 40 may be allocated in a manner that is orthogonal in time, frequency, or space. In this case, the allocation of radio resources does not necessarily have to be 50 / 50. The radio resources may be allocated based on the control accuracy of the required elements 351 and / or the proportion of the RIS elements 351 used in the uplink and downlink, respectively.

[0207] The plurality of channel estimation units 353 included in the RIS each perform an operation related to channel estimation based on the channel estimation signal between the RIS and the base station 20. The RIS acquires the channel estimation results of the plurality of elements 351. Then, the RIS generates channel information between the RIS and the base station 20 based on the acquired channel estimation results. Then, the RIS transmits the channel information between the RIS and the base station 20 to the base station 20 (step S405a).

[0208] Furthermore, the multiple channel estimation units 353 included in the RIS each perform operations related to channel estimation based on the channel estimation signals between the RIS and the terminal device 40. The RIS acquires channel estimation results from the multiple elements 351. Then, the RIS generates channel information between the RIS and the terminal device 40 based on the acquired channel estimation results. Then, the RIS transmits the channel information between the RIS and the terminal device 40 to the terminal device 40 (step S405b).

[0209] The base station 20 and the terminal device 40 acquire the channel information from the RIS, and then perform various processes related to communication based on the channel information.

[0210] In addition, the RIS (transmission path control device 30) of Example 3 may also be provided with one or more band-limiting filters before the phase shifter 352 and the channel estimation unit 353, similar to the RIS of Example 2 (for example, the RIS shown in Figure 14).

[0211] Furthermore, when channel estimation between the RIS and the base station 20 and channel estimation between the RIS and the terminal device 40 are performed simultaneously, some of the multiple elements 351 may be assigned as elements used for channel estimation between the RIS and the base station 20, and the remaining elements may be assigned as elements used for channel estimation between the RIS and the terminal device 40.

[0212] (Configuration Example 1) For example, elements 351 that perform channel estimation between the RIS and the base station 20 and elements 351 that perform channel estimation between the RIS and the terminal device 40 may be arranged alternately. For example, the configuration of the RIS of Example 3 may be a configuration in which the "elements that do not perform channel estimation for frequency band #1" shown in the above-mentioned FIG. 15 are replaced with "elements that perform channel estimation between the RIS and the base station 20," and the "elements that do not perform channel estimation for frequency band #2" are replaced with "elements that perform channel estimation between the RIS and the terminal device 40." In this case, the elements 351 that do not perform channel estimation between the RIS and the base station 20 are positioned so that they are sandwiched on all sides by metasurface elements that perform channel estimation between the RIS and the base station 20. The channel estimation unit 353 of the element 351 that does not perform channel estimation for frequency band #1 may calculate its own channel estimation result based on the channel estimation result of the surrounding elements 351 that perform channel estimation between the RIS and the base station 20. At this time, the channel estimation unit 353 may take the average of the channel estimation results of the surrounding elements 351 as its own channel estimation result. Also, the channel estimation unit 353 may use the channel estimation result of a specific element 351 as its own channel estimation result as is. Of course, the channel estimation unit 353 may calculate the channel estimation result based on a specific calculation formula. The channel estimation result may be interpolated by the channel estimation control unit 333 instead of the channel estimation unit 353. Also, the channel estimation result may be interpolated by the base station 20 and / or the terminal device 40. The channel estimation result of the RIS-terminal device 40 can also be obtained by a similar process.

[0213] (Configuration Example 2) For example, the element 351 that performs channel estimation between the RIS and the base station 20 and the element 351 that performs channel estimation between the RIS and the terminal device 40 may each be arranged in half of the RIS. For example, the configuration of the RIS in Example 3 may be a configuration in which the "element that does not perform channel estimation for frequency band #1" shown in the above-mentioned FIG. 16 is replaced with an "element that performs channel estimation between the RIS and the base station 20" and the "element that does not perform channel estimation for frequency band #2" is replaced with an "element that performs channel estimation between the RIS and the terminal device 40." The element 351 that performs channel estimation between the RIS and the base station 20 and the element 351 that performs channel estimation between the RIS and the terminal device 40 may be arranged in each of the left and right halves of the RIS, each of the top and bottom halves, or each of the diagonal halves. In this case, the RIS may generate channel information regarding the RIS-base station 20 based on, for example, the channel estimation result of the element 351 that performs channel estimation between the RIS and the base station 20. The RIS may also generate channel information relating to the RIS-terminal device 40 relationship based on the channel estimation results of an element 351 that performs channel estimation between the RIS and the terminal device 40, for example.

[0214] (Configuration Example 3) For example, the elements 351 that perform channel estimation between the RIS and the base station 20 and the elements 351 that perform channel estimation between the RIS and the terminal device 40 may be arranged in different ratios. For example, the configuration of the RIS of Example 3 may be a configuration in which the "elements that do not perform channel estimation for frequency band #1" shown in the above-mentioned FIG. 17 are replaced with "elements that perform channel estimation between the RIS and the base station 20" and the "elements that do not perform channel estimation for frequency band #2" are replaced with "elements that perform channel estimation between the RIS and the terminal device 40." Alternatively, the configuration of the RIS of Example 3 may be a configuration in which the "elements that do not perform channel estimation for frequency band #1" shown in the above-mentioned FIG. 17 are replaced with "elements that perform channel estimation between the RIS and the terminal device 40" and the "elements that do not perform channel estimation for frequency band #2" are replaced with "elements that perform channel estimation between the RIS and the base station 20." The RIS may change this ratio according to a predetermined condition. For example, the RIS may change this ratio based on the ratio of the number of elements 351 used for reflection / transmission for each link (e.g., for each uplink / downlink) and / or the required accuracy of channel estimation. The RIS may acquire information on the conditions for determining the ratio (or information on the ratio itself) from the base station 20 and / or the terminal device 40. This information may be included in the channel estimation form information. In the example of FIG. 17 , the RIS may generate channel information regarding the RIS-base station 20 connection based on the channel estimation result of the element 351 that performs channel estimation between the RIS and the base station 20. The RIS may also generate channel information regarding the RIS-terminal device 40 connection based on the channel estimation result of the element 351 that performs channel estimation between the RIS and the terminal device 40.

[0215] In the above three examples, channel estimation is performed in all elements 351, but the multiple elements 351 included in the RIS may include elements 351 that do not perform channel estimation.

[0216] 4-4. Example 4 In Example 4, a case will be described in which the RIS reflects / transmits other signals at the same time as channel estimation. Example 4 is an example of the form shown in (B4) above.

[0217] 19 is a sequence diagram illustrating a channel estimation process according to the fourth embodiment. Hereinafter, the channel estimation process according to the fourth embodiment will be described with reference to FIG.

[0218] The base station 20 requests capability information related to channel estimation of the RIS from the RIS (step S501). The RIS transmits the capability information to the base station 20 (step S502). In the example of Fig. 19, the base station 20 requests the RIS to transmit the capability information, but the terminal device 40 may also request the RIS to transmit the capability information. In this case, the RIS may transmit the capability information to the terminal device 40.

[0219] The acquisition unit 231 of the base station 20 or the acquisition unit 431 of the terminal device 40 acquires capability information from the RIS. The base station 20 or the terminal device 40 transmits a trigger signal to the RIS to trigger a channel estimation operation (step S503). Note that the acquisition unit 431 of the terminal device 40 may acquire the capability information from the RIS. Then, the terminal device 40 may transmit a trigger signal to the RIS. The base station 20 or the terminal device 40 stores channel estimation mode information in this trigger signal. The base station 20 or the terminal device 40 may determine the information (channel estimation mode) to be stored in this channel estimation mode information based on the capability information acquired in step S502.

[0220] The RIS receives a trigger signal from the base station 20 or the terminal device 40. This trigger signal includes channel estimation mode information. In the third embodiment, it is assumed that the mode shown in (B4) above is specified as the channel estimation mode. The RIS controls the operation of the multiple channel estimation units 353 so as to achieve the channel estimation mode specified by the communication device. For example, upon receiving the trigger signal, the RIS switches the circuit connected to the element 351 in which the channel estimation unit 353 is arranged based on the channel estimation mode information.

[0221] The trigger signal (or the channel estimation mode information) may include information about the beam pattern of the transmission signal of the terminal device 40. Based on the information about the beam pattern and / or the channel estimation mode information, the RIS switches the circuit connected to a specified element 351 among the multiple elements 351 to a predetermined circuit (for example, a predetermined frequency filter and / or a channel estimation unit 353 / phase shifter 352). At this time, the information about the beam pattern may be information that specifically specifies the operation of the element 351, or may be information that specifies the direction and / or focus of the beam to be formed.

[0222] The transmitter 232 of the base station 20 transmits a channel estimation signal to the RIS (step S504). The transmitter 432 of the terminal device 40 may transmit the channel estimation signal to the RIS. Furthermore, the transmitter 432 of the terminal device 40 transmits an uplink signal to the RIS (step S505a). The transmitter 232 of the base station 20 may transmit a downlink signal to the RIS.

[0223] The RIS operates the elements 351 to form a desired beam pattern, thereby transmitting a reflected / transmitted signal to the base station 20 (step S505b). Note that when the base station 20 transmits a downlink signal to the RIS, the reflected / transmitted signal is transmitted to the terminal device 40.

[0224] The plurality of channel estimation units 353 included in the RIS each perform an operation related to channel estimation based on the channel estimation signal. The RIS acquires channel estimation results from the plurality of elements 351. The RIS then generates channel information based on the acquired channel estimation results. The RIS then transmits the channel information to the base station 20 (step S506).

[0225] The base station 20 acquires channel information from the RIS. Then, the base station 20 performs various processes related to communication based on the channel information. Note that the terminal device 40 may also acquire the channel information from the RIS. In this case, the terminal device 40 may also perform various processes related to communication based on the channel information.

[0226] In addition, the RIS (transmission path control device 30) of Example 4 may also be provided with one or more band-limiting filters before the phase shifter 352 and the channel estimation unit 353, similar to the RIS of Example 2 (for example, the RIS shown in Figure 14).

[0227] Furthermore, when the RIS reflects / transmits other signals at the same time as channel estimation, some of the elements 351 may be assigned as elements used for channel estimation, and the rest as elements used for reflection / transmission.

[0228] (Configuration Example 1) For example, elements 351 that perform channel estimation and elements 351 used for reflection / transmission may be arranged alternately. For example, the configuration of the RIS of Example 4 may be a configuration in which the "elements that do not perform channel estimation for frequency band #1" shown in FIG. 15 above are replaced with "elements that perform channel estimation," and the "elements that do not perform channel estimation for frequency band #2" are replaced with "elements used for reflection / transmission." In this case, the elements 351 that do not perform channel estimation are positioned so that they are sandwiched on all four sides by metasurface elements that perform channel estimation. The channel estimation unit 353 of the elements 351 that do not perform channel estimation may calculate its own channel estimation result based on the channel estimation results of the surrounding elements 351 that perform channel estimation. In this case, the channel estimation unit 353 may calculate its own channel estimation result by averaging the channel estimation results of the surrounding elements 351. Alternatively, the channel estimation unit 353 may use the channel estimation result of a specific element 351 as its own channel estimation result. Of course, the channel estimation unit 353 may calculate the channel estimation result based on a specific calculation formula. This interpolation of the channel estimation results may be performed by the channel estimation control unit 333, rather than the channel estimation unit 353. Also, this interpolation of the channel estimation results may be performed by the base station 20 and / or the terminal device 40.

[0229] (Configuration Example 2) For example, the elements 351 that perform channel estimation and the elements 351 that are used for reflection / transmission may each be arranged in half of the RIS. For example, the configuration of the RIS of Example 4 may be a configuration in which the "elements that do not perform channel estimation for frequency band #1" shown in the above-mentioned FIG. 16 are replaced with "elements that perform channel estimation" and the "elements that do not perform channel estimation for frequency band #2" are replaced with "elements that are used for reflection / transmission." The elements 351 that perform channel estimation and the elements 351 that are used for reflection / transmission may be arranged in the left and right halves of the RIS, or in the top and bottom halves, or in the diagonal halves. In this case, the RIS may generate channel information based on, for example, the channel estimation result of the elements 351 that perform channel estimation.

[0230] (Configuration Example 3) For example, the elements 351 that perform channel estimation and the elements 351 that are used for reflection / transmission may be arranged in different ratios. For example, the configuration of the RIS of Example 4 may be a configuration in which the "elements that do not perform channel estimation for frequency band #1" shown in FIG. 17 above are replaced with "elements that perform channel estimation," and the "elements that do not perform channel estimation for frequency band #2" are replaced with "elements that are used for reflection / transmission." Alternatively, the configuration of the RIS of Example 4 may be a configuration in which the "elements that do not perform channel estimation for frequency band #1" shown in FIG. 17 above are replaced with "elements that are used for reflection / transmission," and the "elements that do not perform channel estimation for frequency band #2" are replaced with "elements that perform channel estimation." The RIS may change this ratio according to predetermined conditions. For example, the RIS may change this ratio based on the required accuracy of reflection / transmission and / or the required accuracy of channel estimation. The RIS may acquire information on the conditions for determining the ratio (or information on the ratio itself) from the base station 20 and / or the terminal device 40. This information may be included in the channel estimation type information. In the example of Fig. 17, the RIS may generate the channel information based on the channel estimation result of the element 351 that performs channel estimation, for example.

[0231] <<5. Modifications>> The above-described embodiment is merely an example, and various modifications and applications are possible.

[0232] For example, the RIS appearing in the above-described embodiments may be a reflecting plate / reflecting sheet capable of controlling reflection characteristics (e.g., reflection direction / reflectance, etc.), or may be a transmitting plate / transmitting sheet capable of controlling transmission characteristics (e.g., refraction direction). Note that the description of the RIS appearing in each of the above-described embodiments can be replaced with the transmission path control device 30.

[0233] In the above-described embodiment, the transmission path control device 30 is a device having a structure composed of a plurality of elements that can change the characteristics related to the reflection and / or transmission of the incoming radio waves. However, the characteristics that the transmission path control device 30 can change are not limited to these. For example, the transmission path control device 30 may be configured to be able to change the radiation angle (directivity) of the reflected and / or transmitted radio waves.

[0234] Furthermore, in the above-described embodiment, the communication devices that communicate via the transmission path control device 30 (e.g., RIS) are the base station 20 and the terminal device 40, but the communication devices that communicate via the transmission path control device 30 are not limited to these. For example, the communication devices that communicate via the transmission path control device 30 may be the terminal device 40 and another terminal device 40, or the base station 20 and another base station 20. Of course, the communication device may be another communication device such as the management device 10. In this case, the description of the base station 20 and / or the terminal device 40 that appears in the above-described embodiment can be replaced with a description indicating the other communication device, as appropriate.

[0235] Furthermore, in the above-described embodiment, the communication device that transmits the channel estimation signal to the transmission path control device 30 (e.g., RIS) is the base station 20 and / or the terminal device 40, but the communication device that transmits the channel estimation signal is not limited to these. For example, the communication device that transmits the channel estimation signal may be another communication device such as the management device 10. In this case, the description of the base station 20 and / or the terminal device 40 that appears in the above-described embodiment can be replaced with a description indicating the other communication device, as appropriate.

[0236] Furthermore, in the above-described embodiment, the communication device that acquires channel information from the transmission path control device 30 (e.g., RIS) is the base station 20 and / or the terminal device 40, but the communication device that acquires channel information is not limited to these. For example, the communication device that acquires channel information may be another communication device such as the management device 10. In this case, the description of the base station 20 and / or the terminal device 40 that appears in the above-described embodiment can be replaced with a description indicating the other communication device, as appropriate.

[0237] Furthermore, in the above-described embodiment, only one transmission path control device 30 (for example, a RIS) is installed in the communication environment, but multiple transmission path control devices 30 may be installed. In this case, the multiple transmission path control devices 30 may be centrally controlled by a control station. In this case, the control station may perform the processing executed by the transmission path control device 30 in the above-described channel estimation processing. In other words, the control station may perform processing similar to the processing executed by the control unit 33 provided in the transmission path control device 30. Note that the control station may control only one transmission path control device 30. The control station can be considered as a control device for the transmission path control device 30.

[0238] The control device that controls the transmission path control device 30 may be the management device 10, the base station 20, the terminal device 40, the control station, or a control unit thereof (for example, the control unit 13, the control unit 23, or the control unit 43). Also, the control device that controls the transmission path control device 30 may be another transmission path control device 30 or a control unit 33 of another transmission path control device 30. Of course, the control device that controls the transmission path control device 30 may be the control unit 33 of the transmission path control device 30.

[0239] The management device 10, the base station 20, the transmission path control device 30, or the control device that controls the terminal device 40 in this embodiment may be realized by a dedicated computer system or a general-purpose computer system.

[0240] For example, a program for executing the above-described operations is stored on a computer-readable recording medium such as an optical disk, a semiconductor memory, a magnetic tape, or a flexible disk and distributed. Then, for example, the program is installed on a computer and the above-described processing is executed to configure a control device. In this case, the control device may be a device (e.g., a personal computer) external to the management device 10, the base station 20, the transmission path control device 30, or the terminal device 40. Alternatively, the control device may be a device (e.g., the control unit 13, the control unit 23, the control unit 33, or the control unit 43) internal to the management device 10, the base station 20, the transmission path control device 30, or the terminal device 40.

[0241] The communication program may also be stored in a disk device provided in a server device on a network such as the Internet, and may be downloaded to a computer. The above-described functions may also be realized by a combination of an operating system (OS) and application software. In this case, the components other than the OS may be stored on a medium and distributed, or may be stored in a server device and downloaded to a computer.

[0242] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically using a known method. In addition, the information including the processing procedures, specific names, various data, and parameters shown in the above documents and drawings can be changed as desired unless otherwise specified. For example, the various information shown in each drawing is not limited to the information shown in the drawings.

[0243] Furthermore, the components of each device shown in the figure are conceptual functional components and do not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each device is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

[0244] The above-described embodiments can be combined as appropriate within the scope of the present invention without causing any inconsistency in the processing content. The order of the steps shown in the sequence diagrams or flowcharts of the present embodiment can be changed as appropriate.

[0245] Furthermore, for example, the present embodiment can also be implemented as any configuration that constitutes an apparatus or system, such as a processor as a system LSI (Large Scale Integration), a module using multiple processors, a unit using multiple modules, a set in which other functions are added to a unit, or the like (i.e., a configuration of a part of an apparatus).

[0246] In this embodiment, a system refers to a collection of multiple components (devices, modules (components), etc.), regardless of whether all of the components are in the same housing. For example, multiple devices housed in separate housings and connected via a network, etc., and a single device in which multiple modules are housed in a single housing are both systems.

[0247] Furthermore, for example, this embodiment can have a cloud computing configuration in which one function is shared and processed jointly by a plurality of devices via a network.

[0248] <<6. Conclusion>> As described above, according to this embodiment, the communication system includes a communication device (e.g., a base station 20 and / or a terminal device 40) that communicates in a communication environment in which the transmission path control device 30 is installed, and one or more transmission path control devices 30. The transmission path control device 30 includes a plurality of elements 351 that can change characteristics related to reflection or transmission of arriving radio waves. In the transmission path control device 30, a channel estimation unit 353 is arranged in each of two or more elements 351 of the plurality of elements 351.

[0249] The channel estimation unit performs operations related to channel estimation in the arranged elements 351 based on a channel estimation signal transmitted from the communication device. The control unit 33 of the transmission path control device 30 acquires information related to the results of channel estimation from each channel estimation unit 353. Then, the control unit 33 of the transmission path control device 30 transmits channel information generated based on the information related to the results of channel estimation to the communication device.

[0250] This makes it possible to perform channel estimation for each element 351. As a result, more accurate channel estimation becomes possible, and the transmission path control device 30 and / or the communication device can more precisely control the elements 351 or form reflected beams. As a result, the communication device can perform high-quality communication via the transmission path control device 30, thereby realizing effective use of radio wave resources.

[0251] Furthermore, the transmission path control device 30 of this embodiment can perform channel estimation for a plurality of frequency bands and / or propagation paths, thereby reducing overhead caused by channel estimation.

[0252] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure. Furthermore, components of different embodiments and modifications may be combined as appropriate.

[0253] Furthermore, the effects of each embodiment described in this specification are merely examples and are not intended to be limiting, and other effects may also be obtained.

[0254] The present technology may also be configured as follows. (1) A transmission path control device having a structure composed of a plurality of elements capable of changing characteristics related to reflection or transmission of arriving radio waves, the transmission path control device comprising: an acquisition unit that acquires information related to a result of channel estimation at each of two or more elements of the plurality of elements; and a transmission unit that transmits channel information based on the information related to the result of the channel estimation. (2) The transmission path control device according to (1), further comprising: a channel estimation unit that is disposed in each of the two or more elements of the plurality of elements and performs an operation related to channel estimation at the element, the acquisition unit acquiring information based on the operation of the channel estimation unit as the information related to the result of the channel estimation. (3) The transmission path control device according to (2), wherein the channel estimation unit is disposed in all elements of the plurality of elements. (4) The transmission path control device according to (2), wherein the channel estimation unit is disposed in some of the plurality of elements. (5) The transmission path control device according to any one of (2) to (4), wherein the channel estimation unit performs the operation related to the channel estimation based on a signal for the channel estimation transmitted from a communication device. (6) The transmission path control device according to (5), wherein the transmitter transmits the channel information to the communication device. (7) The transmission path control device according to any one of (2) to (6), comprising: a channel estimation control unit that controls operation of a channel estimation unit arranged in each of the two or more elements, wherein the channel estimation control unit controls operation of the channel estimation unit to achieve a channel estimation mode that is predetermined or specified by the communication device out of a plurality of channel estimation modes. (8) The transmission path control device according to (7), comprising: a receiver that receives information regarding a channel estimation mode specified by the communication device, wherein the channel estimation control unit controls operation of the channel estimation unit based on the information regarding the channel estimation mode. (9) The transmission path control device according to (7) or (8), wherein the plurality of channel estimation modes include a mode in which channels are estimated for only a single frequency band.(10) The transmission path control device according to any one of (7) to (9), wherein the plurality of channel estimation modes includes a mode of simultaneously estimating channels in different frequency bands. (11) The transmission path control device according to any one of (7) to (10), wherein the plurality of channel estimation modes includes a mode of simultaneously executing channel estimation between the transmission path control device and a base station and channel estimation between the transmission path control device and a terminal device. (12) The transmission path control device according to any one of (7) to (11), wherein the plurality of channel estimation modes includes a mode of reflecting or transmitting radio waves that arrive simultaneously with channel estimation. (13) The transmission path control device according to any one of (1) to (12), wherein the channel information is information that combines channel estimation results for each of the two or more elements. (14) The transmission path control device according to any one of (1) to (12), wherein the channel information includes information indicating a channel estimation result of one element of the two or more elements, and information on channel estimation results of other elements of the two or more elements, which is expressed as a difference from the channel estimation result of the one element. (15) The transmission path control device according to any one of (1) to (14), comprising: an interpolation unit that interpolates a channel estimation result for an element of the plurality of elements for which a channel estimation result has not been obtained, based on a channel estimation result for an element for which a channel estimation result has been obtained, and the channel information transmitted by the transmission unit is information based on a plurality of channel estimation results including the interpolated channel estimation result. (16) A base station comprising: a transmission unit that has a structure composed of a plurality of elements that can change characteristics related to reflection or transmission of arriving radio waves, and that transmits a signal for channel estimation to a transmission path control device that acquires information on the channel estimation results of each of two or more elements of the plurality of elements; an acquisition unit that acquires channel information based on information on the channel estimation results from the transmission path control device; and a communication control unit that performs communication control based on the channel information.(17) A terminal device comprising: a transmitting unit that has a structure made up of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves, and that transmits a signal for channel estimation to a transmission path control device that acquires information on the results of channel estimation for each of two or more elements of the plurality of elements; and a communication control unit that performs communication using a communication setting determined on the basis of channel information based on the information on the results of the channel estimation. (18) A control method for a transmission path control device having a structure made up of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves, the control method comprising: acquiring information on the results of channel estimation for each of two or more elements of the plurality of elements; and transmitting channel information based on the information on the results of the channel estimation. (19) A communication method that has a structure made up of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves, the control method comprising: transmitting the signal for channel estimation to a transmission path control device that has a structure made up of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves, and that acquires information on the results of channel estimation for each of two or more elements of the plurality of elements; acquiring channel information based on the information on the results of the channel estimation from the transmission path control device; and performing communication control based on the channel information. (20) A communication method having a structure composed of a plurality of elements capable of changing the characteristics related to the reflection or transmission of incoming radio waves, transmitting a signal for the channel estimation to a transmission path control device that acquires information regarding the results of channel estimation for each of two or more elements among the plurality of elements, and performing communication using a communication setting determined based on channel information based on the information regarding the results of the channel estimation.

[0255] REFERENCE SIGNS LIST 1 Communication system 10 Management device 20 Base station 30 Transmission path control device 40 Terminal device 11, 31 Communication unit 21, 41 Wireless communication unit 12, 22, 32, 42 Storage unit 13, 23, 33, 43 Control unit 24, 34, 44 Sensor unit 35 Surface unit 211, 411 Transmission processing unit 212, 412 Reception processing unit 213, 413 Antenna 231, 331, 431 Acquisition unit 232, 332, 432 Transmitting unit 233, 433 Communication control unit 333 Channel estimation control unit 334 Receiving unit 335 Interpolation unit 351 Element 352 Phase shifter 353 Channel estimation unit

Claims

1. A transmission path control device having a structure composed of a plurality of elements capable of changing characteristics related to the reflection or transmission of arriving radio waves, comprising: an acquisition unit that acquires information regarding the results of channel estimation for each of two or more elements among the plurality of elements; and a transmission unit that transmits channel information based on the information regarding the results of the channel estimation.

2. The transmission path control device according to claim 1, further comprising a channel estimation unit arranged in each of two or more of the plurality of elements and performing operations related to channel estimation in the elements, wherein the acquisition unit acquires information based on the operations in the channel estimation unit as information related to the result of the channel estimation.

3. The transmission path control device according to claim 2, wherein the channel estimation unit is arranged in all of the plurality of elements.

4. The transmission path control device according to claim 2, wherein the channel estimation unit is arranged in a portion of the plurality of elements.

5. The transmission path control device according to claim 2, wherein the channel estimation unit executes an operation relating to the channel estimation based on a signal for the channel estimation transmitted from a communication device.

6. The transmission path control device according to claim 5, wherein the transmitting unit transmits the channel information to the communication device.

7. A transmission path control device as claimed in claim 2, further comprising a channel estimation control unit which controls the operation of a channel estimation unit arranged in each of the two or more elements, the channel estimation control unit controlling the operation of the channel estimation unit so as to achieve a channel estimation form that is predetermined or specified by a communication device out of a plurality of channel estimation forms.

8. A transmission path control device according to claim 7, further comprising a receiving unit that receives information relating to a channel estimation mode specified by a communication device, wherein the channel estimation control unit controls the operation of the channel estimation unit based on the information relating to the channel estimation mode.

9. The transmission path control device according to claim 7, wherein the plurality of channel estimation modes includes a mode for estimating a channel for only a single frequency band.

10. The transmission path control device according to claim 7, wherein the plurality of channel estimation modes includes a mode for simultaneously estimating channels in different frequency bands.

11. The transmission path control device according to claim 7, wherein the plurality of channel estimation modes include a mode in which channel estimation between the transmission path control device and a base station and channel estimation between the transmission path control device and a terminal device are simultaneously performed.

12. The transmission path control device according to claim 7, wherein the plurality of channel estimation modes include a mode of reflecting or transmitting radio waves arriving simultaneously with channel estimation.

13. The transmission path control device according to claim 1, wherein the channel information is information obtained by integrating channel estimation results from each of the two or more elements.

14. The transmission path control device according to claim 1, wherein the channel information includes information indicating a channel estimation result of one of the two or more elements, and information indicating a channel estimation result of another of the two or more elements, the channel estimation result being expressed as a difference from the channel estimation result of the one element.

15. A transmission path control device as described in claim 1, further comprising an interpolation unit that interpolates channel estimation results for elements among the plurality of elements for which channel estimation results have not been obtained based on channel estimation results for elements for which channel estimation results have been obtained, and the channel information transmitted by the transmission unit is information based on a plurality of channel estimation results including the interpolated channel estimation results.

16. A base station having a structure composed of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves, comprising: a transmitting unit that transmits a signal for channel estimation to a transmission path control device that acquires information regarding the results of channel estimation for each of two or more of the plurality of elements; an acquiring unit that acquires channel information based on the information regarding the results of channel estimation from the transmission path control device; and a communication control unit that performs communication control based on the channel information.

17. A terminal device having a structure composed of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves, the terminal device comprising: a transmitting unit that transmits a signal for channel estimation to a transmission path control device that acquires information regarding the results of channel estimation for each of two or more of the plurality of elements; and a communication control unit that performs communication using communication settings determined based on channel information based on the information regarding the results of the channel estimation.

18. A control method for a transmission path control device having a structure composed of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves, comprising the steps of: acquiring information regarding the results of channel estimation for each of two or more of the plurality of elements; and transmitting channel information based on the information regarding the results of the channel estimation.

19. A communications method comprising: a structure made up of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves; transmitting a signal for channel estimation to a transmission path control device that acquires information regarding the results of channel estimation for each of two or more of the plurality of elements; acquiring channel information based on the information regarding the results of the channel estimation from the transmission path control device; and performing communications control based on the channel information.

20. A communications method comprising: a structure made up of a plurality of elements capable of changing characteristics related to the reflection or transmission of incoming radio waves; transmitting a signal for channel estimation to a transmission path control device that acquires information regarding the results of channel estimation for each of two or more of the plurality of elements; and communicating using communication settings determined based on channel information based on the information regarding the results of the channel estimation.

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