Base station, terminal device, communication method, and communication system

Abstract

The base station includes: a forming unit that forms a point cell for concentrating power at a specific point by cooperative control of a plurality of antennas; and a tracking unit that performs a process for causing the terminal device to track the point cell.

Description

Technical Field

[0001] This disclosure relates to base stations, terminal devices, communication methods, and communication systems. Background Technology

[0002] Technologies related to wireless communication have seen positive development. Next-generation wireless communication promises further improvements in communication performance (e.g., improved frequency utilization efficiency). As one technique for improving frequency utilization efficiency, a method for concentrating power at a specific point using near-field phase differences has been disclosed (e.g., Non-Patent Document 1).

[0003] Citation List

[0004] Non-patent literature

[0005] Non-Patent Literature 1: Mingyao Cui, Linglong Dai, Robert Schober and Lajos Hanzo, “Near-Field Wideband Beamforming for Extremely Large Antenna Arrays”, arXiv preprint arXiv: 2109.10054, September 2021. Summary of the Invention

[0006] Technical issues

[0007] The above technologies (technologies that perform power concentration at specific points) are presumably designed to enable more advanced spatial multiplexing. However, simply applying these technologies to radio access networks does not necessarily guarantee wireless communication with high performance (e.g., higher frequency utilization efficiency, greater capacity, higher speed, lower latency, higher reliability, massive / high density, lower power consumption, or lower processing load).

[0008] In view of this, this disclosure proposes a base station, terminal device, communication method, and communication system capable of achieving high communication performance.

[0009] It should be noted that the above problems or objectives are merely one of many problems or objectives that can be solved or achieved by the various embodiments disclosed in this specification.

[0010] Solution to the problem

[0011] To address the above problems, a base station according to an embodiment of the present disclosure includes: a forming unit configured to form a point cell by concentrating power at a specific point through the coordinated control of a plurality of antennas; and a tracking unit configured to perform processing for enabling the point cell to track a terminal device. Attached Figure Description

[0012] Figure 1 This is a diagram used to illustrate power concentration techniques (point formation).

[0013] Figure 2 It is a graph used to illustrate the near field and far field.

[0014] Figure 3 This is a diagram illustrating the Fraunhofer distance, which defines the boundary between the near and far fields.

[0015] Figure 4 This is a diagram illustrating an example of point formation using distributed antennas.

[0016] Figure 5 It is a diagram used to illustrate the processing according to type 1.

[0017] Figure 6 It is a diagram used to illustrate the processing according to type 2.

[0018] Figure 7 This is a diagram illustrating the configuration of a communication system according to this embodiment.

[0019] Figure 8 This is a diagram illustrating the configuration of the management device according to this embodiment.

[0020] Figure 9 This is a diagram illustrating the configuration of a base station according to this embodiment.

[0021] Figure 10 This is a diagram illustrating the configuration of a relay station according to this embodiment.

[0022] Figure 11 This is a diagram illustrating the configuration of a terminal device according to this embodiment.

[0023] Figure 12 This is a flowchart illustrating an example of initial connection processing.

[0024] Figure 13 This is a diagram illustrating a contention-based random access process.

[0025] Figure 14 This is a diagram illustrating a non-contention-based random access process.

[0026] Figure 15 This is a diagram illustrating the two-step random access process.

[0027] Figure 16 This is a diagram used to illustrate the terminal tracking cell formation component according to type 1.

[0028] Figure 17 This is a diagram used to illustrate the terminal tracking cell formation component according to type 2.

[0029] Figure 18 This is a diagram illustrating an example of a mapping of a conventional reference signal.

[0030] Figure 19 This is a diagram illustrating an example of a reference signal mapping according to this embodiment.

[0031] Figure 20 This is a diagram illustrating another example of a mapping of a reference signal according to this embodiment.

[0032] Figure 21 This is a diagram illustrating an example of a point cell determination component based on a synchronization signal.

[0033] Figure 22 This is a diagram illustrating another example of a point cell determination component based on a synchronization signal. Detailed Implementation

[0034] Embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. In each of the following embodiments, the same sites are denoted by the same reference numerals, and repeated descriptions thereof will be omitted.

[0035] Furthermore, in this specification and accompanying drawings, multiple components with substantially the same functional configuration will be distinguished by appending different letters or numbers after the same reference numerals. For example, multiple configurations with substantially the same functional configuration may be distinguished as terminal devices 401, 402, and 403, as needed. However, when it is not particularly necessary to distinguish multiple components with substantially the same functional configuration, only the same reference numerals are given. For example, when it is not particularly necessary to distinguish terminal devices 401, 402, and 403, they are simply referred to as terminal device 40.

[0036] The one or more embodiments described below (including implementation examples and modifications) can be implemented independently. On the other hand, at least some of the embodiments described below can be appropriately combined with at least some of the other embodiments. The multiple embodiments may include novel features that differ from each other. Therefore, the multiple embodiments can help achieve or solve different objectives or problems and can exhibit different effects.

[0037] This disclosure will be described in the following order.

[0038] 1. Overview

[0039] 1-1. Question

[0040] 1-2. Power Concentration Technology (Point Formation)

[0041] 1-3. Solution Overview

[0042] 2. Communication system configuration

[0043] 2-1. Configuration of Management Device

[0044] 2-2. Base Station Configuration

[0045] 2-3. Relay Station Configuration

[0046] 2-4. Configuration of Terminal Device

[0047] 3. Basic Operations of Communication Systems

[0048] 3-1. Initial Connection Processing

[0049] 3-2. Random Access Procedure

[0050] 3-3. Details of the random access procedure in NR

[0051] 3-4. Two-step RACH in NR

[0052] 4. Operation of the communication system

[0053] 4-1. Example of Terminal Tracking Cell Formation

[0054] 4-2. Information used to form a terminal tracking cell

[0055] 4-3. Exemplary Operations Related to Terminal Tracking

[0056] 4-4. Details of Type 1

[0057] 4-5. Details of Type 2

[0058] 4-6. Rollback

[0059] 4-7. Signal Processing

[0060] 5. Methods for initial connection with the terminal tracking cell

[0061] 5-1. Overview of methods for determining cell locations

[0062] 5. Details of the methods for determining the location of the residential area.

[0063] 6. Modification

[0064] 6-1. Functional Separation

[0065] 6-2. Point Formation

[0066] 6-3. Other modifications

[0067] 7. Conclusion

[0068] <<1. Overview>>

[0069] Before describing this embodiment in detail, an outline of this embodiment will be described.

[0070] <1-1. Question>

[0071] In recent years, next-generation wireless communication has been under discussion. To meet the demands of achieving advancements such as high-speed communication beyond 5G NR, low-latency and high-reliability communication, and massive / high-density communication, as well as supporting multiple aspects simultaneously, further improvements in frequency utilization efficiency are needed. Techniques for improving frequency utilization efficiency include publicly available techniques that utilize near-field phase differences to concentrate power at specific points (hereinafter referred to as "power concentration techniques").

[0072] Power concentration technology may enable more advanced spatial multiplexing. However, simply applying this technology to radio access networks does not necessarily guarantee high-performance wireless communication (e.g., higher frequency utilization efficiency, greater capacity, higher speed, lower latency, higher reliability, massive / high density, lower power consumption, or lower processing load).

[0073] For example, in conventional technologies, cell design takes into account cell coverage in order to provide communication in a specific area. However, in the case of advanced spatial multiplexing achieved through power concentration technology, cell coverage will differ from that in conventional technologies. In this case, continued use of conventional cell handover procedures (e.g., conventional handover procedures) may lead to various problems such as communication delays due to frequent handover processes.

[0074] For example, in conventional technologies, base stations form planar or beam-shaped cells. However, when power concentration techniques are applied to wireless communication networks, base stations may form small, point-like cells. In this case, using conventional technologies, even slight movement of the terminal device can trigger a routine handover process, leading to significant communication delays.

[0075] Therefore, this embodiment will examine the mobile communication of a terminal device when power concentration technology is applied to a wireless communication network.

[0076] In the following description, power concentration techniques will be referred to as point formation in some cases.

[0077] <1-2. Power Concentration Technology (Point Formation)>

[0078] Before describing the overview of the solution, the power concentration technology (point formation) will be described.

[0079] Figure 1This is a diagram used to illustrate power concentration techniques (dot formation). In conventional cellular mobile communications, base stations (e.g., eNB (eNodeB), gNB (gNodeB), or RAN nodes (including EUTRAN and NGRAN)) form planar or beamform cells. Figure 1 In the example, the left diagram (classic cell) illustrates the state where the base station forms a planar cell, while the middle diagram (beamforming) illustrates the state where the base station forms a beamform cell. Using this configuration, the base station provides communication for terminal devices (e.g., user equipment (UE)). To meet the requirements of advanced technologies, such as further improving high-speed communication as well as low-latency and high-reliability communication, next-generation cellular communication needs to maximize frequency utilization efficiency.

[0080] Currently attracting attention are technologies that utilize point-based cell formation (e.g., power concentration techniques). This involves the coordinated control of a large number of transmission antennas to form point-like cells, surpassing spatial separation techniques achieved through conventional beamforming. Figure 1 In the example, the diagram on the right (dot formation) illustrates the state of a base station forming a dotted cell. This technique is referred to as dot formation in the following text, but can be represented using other annotations. While conventional beamforming cannot perform beam direction multiplexing, dot formation enables three-dimensional multiplexing. This allows for further enhancement of simultaneous communication by multiple terminals. Furthermore, dot formation can suppress interference to multiple terminals. This improves the overall system communication quality, reduces the communication connection drop rate, and further enhances multi-connection communication.

[0081] Point formation is a technique based on the phase difference of individual radio waves transmitted from a large number of transmission antennas under consideration, and performs coordinated operation of the large number of transmission antennas to apply in-phase combination to the radio waves at a specific point, thereby maximizing the received power at that specific point. Since the radio waves transmitted from the large number of transmission antennas are received with random phases at points other than the specific point, the received power is suppressed by averaging. This achieves point formation of a cell at the specific point. Here, when controlling the phase difference of the radio waves transmitted from the large number of transmission antennas, for example, the control device can control the initial phase of each transmission antenna or can control the amplitude of each transmission antenna.

[0082] At this point, when transmitting radio waves from a single transmission panel with a large number of transmission antenna elements, it is also permissible to consider the characteristics of the near field. Figure 2 This is a diagram used to illustrate near-field and far-field communication. Base stations are typically assumed to communicate with remote terminal devices such as smartphones. This leads to... Figure 2The right-hand side shows a standard check based on the far-field condition. However, in the future, larger transmission panels may be used for communication. This makes it possible to perform communication considering the phase difference as a characteristic of the near-field region. Point formation can be used in the near-field region. Figure 3 This is a diagram illustrating the Fraunhofer distance, which defines the boundary between the near and far fields.

[0083] Here, although an example of applying point formation in the near field has been described above, point formation can be implemented in environments where phase difference can be taken into account. Therefore, it is possible to perform point formation in environments with a large number of distributed antennas around the receiving point, regardless of the Fraunhofer distance. Figure 4 This is a diagram illustrating an example of point formation using distributed antennas. Figure 4 In the example, the base station includes a control unit (in Figure 4 In the example, the central unit (CU) controls multiple antennas, thereby controlling the transmission antenna. Figure 4 In the example, the CU and the transmission antenna are optically connected, but not necessarily. Note that each of the multiple transmission points (transmission antennas) can be a base station. Furthermore, one or more base stations can control multiple transmission points (transmission antennas). Additionally, the multiple antennas (multiple transmission points) can be one or more transmission panels comprising multiple transmission antennas (antenna elements).

[0084] <1-3. Solution Overview>

[0085] Based on the above, an overview of the solution in this embodiment will be described.

[0086] Figure 5 and Figure 6 This is a diagram used to illustrate an overview of the solution in this embodiment. Figure 5 This is a diagram illustrating a first example of the solution of this embodiment (hereinafter referred to as Type 1). Figure 6 This is a diagram illustrating a second example (hereinafter referred to as Type 2) of the solution of this embodiment.

[0087] The communication system of this embodiment includes a base station and a terminal device. In the figures, a transmission point indicates a transmission antenna included in or controlled by the base station. A receiving point indicates a receiving antenna included in the terminal device. The base station forms a point cell using power concentration technology (point formation). For example, the base station includes a control unit that controls multiple antennas. The base station performs coordinated control of the multiple antennas to concentrate power at a specific point, thereby forming a point cell.

[0088] In this embodiment, the base station performs processing for enabling a point cell to track a terminal device. For example, the base station acquires information about the terminal device. For instance, the base station acquires at least one of information about the terminal device's direction of movement, information about the terminal device's speed of movement, and location information as information about the terminal device. Furthermore, the base station may acquire information about the interference power received by the terminal device as information about the terminal device, or it may acquire information about the terminal device's movement schedule. The base station performs processing for enabling a point cell to track the terminal device based on the information about the terminal device. The processing for enabling a point cell to track the terminal device can be of type 1 or type 2 as described below.

[0089] (Type 1)

[0090] Figure 5 This diagram illustrates the process according to Type 1. In Type 1, the base station forms multiple point cell PCs covering an area surrounded by transmission antennas. The base station then performs a process to switch the point cell PCs to which the terminal device is connected, so that the point cell PCs track the terminal device moving within that area. For example, in Type 1, the terminal device is configured to connect to two or more of the multiple point cell PCs. The base station notifies the terminal device of information about the point cells to which the terminal device will connect in the future among the two or more point cell PCs to which it is attached. For example, the base station notifies the terminal device of the connection order of the point cells as information about the point cell PCs to which the terminal device will connect in the future. The terminal device then pre-connects to one or more point cell PCs based on the information provided by the base station. For example, the terminal device connects to point cell PCs for future communication in addition to the point cell PCs currently used for communication.

[0091] (Type 2)

[0092] Figure 6 This diagram illustrates the processing according to Type 2. In Type 2, the base station dynamically changes settings related to the generation of the point cell PC to track the movement direction of the terminal device. That is, in Type 2, the base station dynamically moves the point cell PC to track the movement of the terminal device. In this case, the base station can dynamically move the point cell PC based on the movement information of the terminal device transmitted by the terminal device.

[0093] In this manner, in this embodiment, the base station performs the processing for enabling the point cell to track the terminal device. Therefore, even when the terminal device moves, it can maintain uninterrupted connection to the point cell. For example, in Type 1, since the terminal device can be pre-connected to one or more point cell PCs, a smooth point cell handover can be performed. In Type 2, since the point cell PC moves according to the movement of the terminal device, the terminal device can maintain its connection to the point cell even when it moves. This enables the communication system to achieve high communication performance.

[0094] The overview of this embodiment has been described above. The communication system 1 of this embodiment will be described in detail below.

[0095] <<2. Configuration of the Communication System>>

[0096] First, the configuration of communication system 1 will be described.

[0097] Figure 7 This illustration shows an example of the configuration of a communication system 1 according to this embodiment. The communication system 1 includes a management device 10, a base station 20, a relay station 30, and a terminal device 40. Through the cooperation of the various wireless communication devices constituting the communication system 1, the communication system 1 provides a wireless network capable of mobile communication for users. The wireless network in this embodiment includes, for example, a radio access network (RAN) and a core network (CN). In this embodiment, the wireless communication device is a device with wireless communication capabilities, and... Figure 7 In the example, the device corresponds to base station 20, relay station 30 and terminal device 40.

[0098] The communication system 1 may include multiple management devices 10, multiple base stations 20, multiple relay stations 30, and multiple terminal devices 40. Figure 7 In the example, communication system 1 includes management devices 101 and 102 as management devices 10, and base stations 201, 202 and 203 as base stations 20. In addition, communication system 1 includes relay stations 301 and 302 as relay stations 30, and terminal devices 401, 402 and 403 as terminal devices 40.

[0099] Terminal device 40 can be configured to connect to a network using a radio access technology (RAT) such as LTE, NR, 6G, Wi-Fi, or Bluetooth (registered trademark) . In this case, terminal device 40 can be configured to use different radio access technologies (wireless communication methods). For example, terminal device 40 can be configured to use NR and Wi-Fi. Furthermore, terminal device 40 can be configured to use different cellular communication technologies (e.g., LTE and NR, or 6G). LTE and NR are types of cellular communication technologies that enable mobile communication for the terminal device by using a cellular layout covering multiple areas by a base station. 6G is also a type of cellular communication technology that enables mobile communication for the terminal device by using a cellular layout covering multiple areas by a base station.

[0100] In the following, it is assumed that "LTE" includes LTE-Advanced (LTE-A), LTE-Advanced Pro (LTE-A Pro), and Evolved Universal Terrestrial Radio Access (EUTRA). Furthermore, it is assumed that NR includes New Radio Access Technology (NRAT) and further EUTRA (FEUTRA). A single base station 20 can manage multiple cells. In the following, cells corresponding to LTE can be referred to as LTE cells, and cells corresponding to NR can be referred to as NR cells.

[0101] NR is the next-generation (fifth-generation) radio access technology following LTE (including LTE-Advanced and LTE-Advanced Pro, the fourth-generation communication technology). NR is a radio access technology that can support a variety of use cases, including enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable and low-latency communications (URLLC). NR is standardized by 3GPP (registered trademark) Rel-15 as a technical framework supporting use cases, requirements, deployment scenarios, etc., in these use cases. Furthermore, it requires exceeding the requirements of 5G and 6G in achieving high speed and high capacity, low latency / high reliability, and multiple simultaneous connections.

[0102] 6G is the next generation of cellular communication technology after NR or 5GS (5G systems), the fifth generation of mobile communication, and includes radio access technologies as well as network technologies between base stations, core networks, and data networks. 6G can include technologies that complicate (called extreme connectivity) each of the technologies used to implement eMBB, mMTC, and URLLC, which have been defined as major use cases or requirements in NR, as well as new technologies in emerging aspects. For example, new technologies could theoretically include technologies related to artificial intelligence (AI: including cognitive networks, AI-native air interfaces), sensing (including radar sensing, networks as sensors), and terahertz communication.

[0103] The wireless network can be compatible with radio access technologies (RATs), such as Long Term Evolution (LTE), New Radio (NR), and 6G. LTE, NR, and 6G are all types of cellular communication technologies and enable mobile communication of terminal devices by using a cellular layout covering multiple areas by base stations. The radio access method used by the communication system 1 is not limited to LTE, NR, or 6G, and can be, for example, other radio access methods such as Wideband Code Division Multiple Access (W-CDMA) and Code Division Multiple Access 2000 (CDMA2000).

[0104] Base station 20 and relay station 30 can each be a ground station or a non-ground station. A non-ground station can be a satellite station or an aviation station. When the non-ground station is a satellite station, the wireless network can be a bend-tube (transparent) mobile satellite communication system.

[0105] In this embodiment, a ground station (also called a ground base station) refers to a base station or relay station installed on the ground. "Ground" not only refers to land but also to a broad ground location, including underground, above water, and underwater. Note that in the following description, the term "ground station" may sometimes also be referred to as "gateway".

[0106] In LTE, base stations can be referred to as Evolved Node B (eNodeB) or eNB. NR base stations can be referred to as gNodeB or gNB. 6G base stations can be referred to as 6G NodeB (6GNB). In LTE, NR, and 6G, terminal devices (also called mobile stations or terminals) can be referred to as User Equipment (UE). A terminal device is a type of communication device and is also called a mobile station or terminal.

[0107] Terminal device 40 can connect to the network using radio access technologies (wireless communication methods) other than LTE, NR, 6G, Wi-Fi, or Bluetooth. For example, terminal device 40 can connect to the network using Low Power Wide Area Network (LPWA) communication. Alternatively, terminal device 40 can connect to the network using proprietary standard wireless communication.

[0108] Here, LPWA communication refers to wireless communication that enables low-power wide-range communication. For example, LPWA wireless is Internet of Things (IoT) wireless communication using a specified low-power wireless band (e.g., the 920MHz band) or an Industrial-Scientific-Medical (ISM) band. The LPWA communication used by the terminal device 40 can conform to LPWA standards. Examples of LPWA standards include ELTRES, ZETA, SIGFOX, LoRaWAN, and NB-IoT. Of course, LPWA standards are not limited to these and can be other LPWA standards.

[0109] Figure 7 Each wireless communication device in the system can be logically considered a device. That is, a part of each wireless communication device can be implemented by a virtual machine (VM), container, Docker, etc., and they can be physically implemented on the same hardware.

[0110] 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 a structure or mobile body. The structure or mobile body itself can be considered a wireless communication device. Furthermore, the concept of a wireless communication device includes not only terminal device 40, but also base station 20 and relay station 30. A wireless communication device is a type of processing device and information processing device. A wireless communication device can also be referred to as a transmitting device or a receiving device.

[0111] In this embodiment, resources include, for example, indication frequency, time, resource elements (including REG, CCE, CORESET), resource blocks, bandwidth portions, component carriers, symbols, sub-symbols, time slots, micro-time slots, sub-time slots, subframes, frames, PRACH timing, timing, codes, multiple access physical resources, multiple access signatures, and subcarrier spacing (parameter set (Numerology)).

[0112] The configurations of the various wireless communication devices included in communication system 1 will be described in detail below. The configurations of each wireless communication device shown below are merely examples. The configuration of each wireless communication device may differ from the configurations described below.

[0113] <2-1. Configuration of Management Device>

[0114] Management device 10 is an information processing device (computer) that manages the wireless network. For example, management device 10 is an information processing device that manages the communications of base station 20. For example, management device 10 may be a device with functions such as a Mobility Management Entity (MME). Management device 10 may be a device with functions such as Access and Mobility Management Function (AMF) and / or Session Management Function (SMF). MME, AMF, and SMF are control plane network function nodes in the core network. Management device 10 may be a device with functions such as a 6G Control Plane Network Function (6G CPNF). 6G CPNF may include one or more logical nodes.

[0115] Of course, the functions of management device 10 are not limited to MME, AMF, SMF, or 6G CPNF. Management device 10 can be a device with functions such as Network Slice Selection Function (NSSF), Authentication Server Function (AUSF), Policy Control Function (PCF), or Unified Data Management (UDM). In addition, management device 10 can be a device with functions such as Home Subscriber Server (HSS).

[0116] Note that the management device 10 may have gateway functionality. For example, the management device 10 may have functionality such as a Serving Gateway (S-GW) or a Packet Data Network Gateway (P-GW). Furthermore, the management device 10 may have functionality such as a User Plane Function (UPF). In this case, the management device 10 may have multiple UPFs. The management device 10 may also be a device with functionality such as a 6G Control User Plane Network Function (6G UPNF).

[0117] The core network includes multiple network functions. Each network function can be integrated into a single physical device or distributed across multiple physical devices. That is, the management device 10 can be deployed in a distributed manner across multiple devices. Furthermore, this distributed arrangement can be controlled to execute dynamically. The base station 20 and the management device 10 constitute a network and provide wireless communication services to the terminal device 40. The management device 10 is connected to the Internet, and the terminal device 40 can use various services provided on the Internet via the base station 20.

[0118] Note that the management device 10 is not necessarily a device constituting the core network. For example, suppose the core network is a Wideband Code Division Multiple Access (W-CDMA) or Code Division Multiple Access 2000 (CDMA2000) core network. In this case, the management device 10 can be a device used as a Radio Network Controller (RNC).

[0119] Figure 8 This diagram illustrates 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. Figure 8 The configuration shown is a functional configuration, and the hardware configuration may differ from this configuration. The functionality of management device 10 can be implemented in multiple physically separate configurations in a statically or dynamically distributed manner. Management device 10 may consist of multiple server devices.

[0120] Communication unit 11 is a communication interface for communicating with wireless communication devices (e.g., base station 20 or relay station 30). Communication unit 11 can be a network interface or a device connection interface. Communication unit 11 can be a local area network (LAN) interface such as a network interface card (NIC), or a universal serial bus (USB) interface including a USB host controller, USB port, etc. Communication unit 11 can be a wired interface or a wireless interface. Communication unit 11 serves as a communication component of management device 10. Communication unit 11 is controlled by control unit 13.

[0121] Storage unit 12 is a read / write storage device, such as dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, or hard disk. Storage unit 12 serves as a storage component within management device 10. Storage unit 12 stores, for example, the connection status of terminal device 40. Storage unit 12 stores the Radio Resource Control (RRC) status, EPS Connection Management (ECM) status, or 5G System Connection Management (CM) status of terminal device 40. Storage unit 12 can also be used as a unit referred to as "home memory" (user information database), which stores the location information of terminal device 40.

[0122] Control unit 13 is a controller for the various components of management device 10. For example, control unit 13 can be implemented by a processor such as a central processing unit (CPU) or a microprocessor (MPU). Specifically, control unit 13 can be implemented by the processor executing various programs stored in storage devices within management device 10 using random access memory (RAM) as a working area. Control unit 13 can be implemented by an integrated circuit such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). Furthermore, control unit 13 can be implemented by a graphics processing unit (GPU). CPU, MPU, ASIC, FPGA, and GPU can all be considered as controllers. Control unit 13 may include multiple physically separate objects. For example, control unit 13 may include multiple semiconductor chips.

[0123] <2-2. Base Station Configuration>

[0124] Base station 20 is a wireless communication device that performs wireless communication with other wireless communication devices (e.g., relay station 30, terminal device 40, or another base station 20). Base station 20 can wirelessly communicate with terminal device 40 via relay station 30, or it can directly perform wireless communication with terminal device 40.

[0125] Base station 20 is a device corresponding to a radio base station (base station, node B, eNB, gNB, or 6GNB, etc.) or radio access point. Base station 20 can be a radio relay station. Base station 20 can be an optical link device called a remote radio head (RRH). Furthermore, base station 20 can be a receiving station, such as a field pickup unit (FPU). Base station 20 can be an integrated access and backhaul (IAB) donor node or IAB relay node, which provides radio access channels and radio backhaul channels through the use of time division multiplexing, frequency division multiplexing, or space division multiplexing.

[0126] The radio access technology used by base station 20 can be cellular communication technology. The radio access technology used by base station 20 can be wireless LAN technology. For example, the radio access technology used by base station 20 can be low-power wide-area (LPWA) communication technology. Note that the radio access technology used by base station 20 is not limited to these and can be other radio access technologies. The wireless communication used by base station 20 can be wireless communication using millimeter waves or wireless communication using terahertz waves (THz waves). The wireless communication used by base station 20 can be wireless communication using radio waves or wireless communication using infrared or visible light (optical wireless communication). Base station 20 can be able to perform non-orthogonal multiple access (NOMA) communication with terminal device 40. Here, NOMA communication refers to communication using non-orthogonal resources (transmission, reception, or both). Note that base station 20 can be able to perform NOMA communication with another base station 20.

[0127] Base stations 20 can communicate with each other via a base station core network interface (e.g., NG interface, S1 interface, etc.). This interface can be implemented as a wired or wireless interface. Furthermore, base stations can communicate with each other via an inter-base station interface (e.g., Xn interface, X2 interface, F1 interface, etc.). This interface can also be implemented as a wired or wireless interface.

[0128] A base station (also known as a "base station facility") conceptually includes not only donor base stations but also relay base stations (also known as "relay stations"). A relay base station can be any of an RF repeater, a smart repeater, and a smart surface. A base station conceptually includes not only the structure having the functions of a base station but also the equipment installed within the structure.

[0129] Examples of structures include buildings such as high-rise buildings, houses, steel towers, station facilities, airport facilities, port facilities, office buildings, school buildings, hospitals, factories, commercial facilities, or stadiums. Conceptually, structures include not only buildings but also non-building structures such as tunnels, bridges, dams, fences, steel columns, and facilities such as cranes, gates, and windmills. Conceptually, structures include not only land-based (in a narrow sense) or underground structures but also above-water structures such as docks or large floating bodies and underwater structures such as ocean observation facilities. A base station can also be referred to as an information processing device.

[0130] Base station 20 can be a donor station or a relay station. Base station 20 can be a fixed station or a mobile station. A mobile station is a wireless communication device configured to be mobile (e.g., a base station). In this case, base station 20 can be a device installed on a mobile body, or it can be the mobile body itself. For example, a mobile relay station can be considered as base station 20 as a mobile station. In addition, devices designed to be mobile and having base station functions (at least a part of the base station functions), such as unmanned aerial vehicles (UAVs) represented by drones or smartphones, also correspond to base station 20 as a mobile station.

[0131] Here, a mobile body can be a mobile terminal such as a smartphone or mobile phone. A mobile body can be a body that moves on land (in the narrow sense) (e.g., vehicles such as cars, motorcycles, buses, trucks, electric bicycles, trains, linear electric vehicles), or a body that moves underground (e.g., through tunnels) (e.g., a subway). A mobile body can be a body that moves on water (e.g., ships such as passenger ships, cargo ships, or hovercraft), or a body that moves underwater (e.g., submersibles such as submarines, submarines, or unmanned submersibles). A mobile body can be a body that moves in the atmosphere (e.g., aircraft such as airplanes, airships, or drones).

[0132] Base station 20 can be a ground-based base station (ground station) installed on the ground. Base station 20 can be a base station deployed on a structure on the ground, or it can be a base station installed in a mobile body moving on the ground. Base station 20 can be an antenna installed in a structure such as a building, and a signal processing device connected to the antenna. Base station 20 can be the structure or the mobile body itself. "Ground" not only refers to land (land in the narrow sense), but also to a land surface location in a broad sense, including underground, above water, and underwater. Base station 20 is not limited to a ground-based base station. In the case where communication system 1 is a satellite communication system, base station 20 can be an aircraft station. From the perspective of a satellite station, an aircraft station located on Earth is a ground station.

[0133] Base station 20 is not limited to ground stations. Base station 20 can be a non-ground base station (non-ground station) that can float in the air or space. For example, base station 20 can be an aircraft station or a satellite station.

[0134] A satellite station is a device capable of floating outside the atmosphere. A satellite station can be a device mounted on a spacecraft, such as an artificial satellite, or it can be the spacecraft itself. A spacecraft is a moving body that moves outside the atmosphere. Examples of spacecraft include artificial bodies such as artificial satellites, spacecraft, space stations, or probes. A satellite used as a satellite station can be any of the following: a low Earth orbit (LEO) satellite, a medium Earth orbit (MEO) satellite, a geostationary orbit (GEO) satellite, or a highly elliptical orbit (HEO) satellite. A satellite station can be a device mounted on a low Earth orbit satellite, a medium Earth orbit satellite, a geostationary orbit satellite, or a highly elliptical orbit satellite.

[0135] An aircraft station is a wireless communication device capable of floating in the atmosphere, such as an aircraft. An aircraft station can be a device mounted on an aircraft, or it can be the aircraft itself. Conceptually, aircraft include not only heavy aircraft such as airplanes or gliders, but also light aircraft such as balloons or airships. Aircraft also include not only heavy or light aircraft, but also rotorcraft such as helicopters or autogyros. An aircraft station, or an aircraft equipped with an aircraft station, can be an unmanned aerial vehicle, such as a drone.

[0136] Unmanned aerial vehicles (UAVs) conceptually include unmanned aircraft systems (UAS) and tethered UAS. Conceptually, UAVs also include lighter-than-air (LTA) UAS and heavier-than-air (HTA) UAS. Conceptually, UAVs also include high-altitude unmanned aircraft system (UAS) platforms (HAP).

[0137] The coverage area of ​​base station 20 can be relatively large, such as a macro cell, or relatively small, such as a pico cell. The coverage area of ​​base station 20 can also be extremely small, such as a femtocell. Base station 20 can have beamforming capabilities. In this case, base station 20 can form a cell or service area for each beam. Base station 20 can also include spot formation capabilities. Spot formation is a technique that uses near-field phase difference to concentrate power at a specific point (power concentration technique). In this case, base station 20 can form a cell or service area for each point.

[0138] Figure 9 This diagram illustrates the configuration of base station 20 according to this embodiment. Base station 20 includes a wireless communication unit 21, a storage unit 22, and a control unit 23. Figure 9The configuration shown is a functional configuration, and the hardware configuration may differ from this configuration. Furthermore, the functionality of base station 20 can be implemented in a distributed manner across multiple physically separate configurations.

[0139] The wireless communication unit 21 is a signal processing unit used to perform wireless communication with other wireless communication devices (e.g., relay station 30, terminal device 40, or another base station 20). The wireless communication unit 21 is controlled by the control unit 23. The wireless communication unit 21 can support one or more radio access schemes. The wireless communication unit 21 can support at least one of NR, LTE, and 6G. In addition to NR, LTE, and 6G, the wireless communication unit 21 can also support W-CDMA, cdma2000, etc. The wireless communication unit 21 can support automatic repeater technologies, such as Hybrid Automatic Repeat Request (HARQ).

[0140] The wireless communication unit 21 includes a transmission processing unit 211, a receiving processing unit 212, and an antenna 213. The wireless communication unit 21 may include multiple transmission processing units 211, multiple receiving processing units 212, and multiple antennas 213. When the wireless communication unit 21 supports multiple radio access schemes, each part of the wireless communication unit 21 can be configured individually for each radio access scheme. The transmission processing unit 211 and the receiving processing unit 212 can be configured individually for LTE, NR, and 6G. The antenna 213 may include multiple antenna elements, such as multiple patch antennas. The wireless communication unit 21 may have beamforming capabilities. For example, the wireless communication unit 21 may have polarization beamforming capabilities using vertically polarized waves (V-polarized waves) and horizontally polarized waves (H-polarized waves) (or it may have polarization beamforming capabilities using dual polarization in polarization directions at 45 degrees and -45 degrees to the vertical direction). The wireless communication unit 21 may also include dot formation capabilities.

[0141] The transmission processing unit 211 performs transmission processing of downlink control information and downlink data. The transmission processing unit 211 encodes the downlink control information and downlink data input from the control unit 23 using encoding methods such as block coding, convolutional coding, or Turbo coding. The encoder can perform encoding using polar codes or low-density parity-check (LDPC) codes. The transmission processing unit 211 modulates the coded bits using a predetermined modulation scheme such as BPSK, QPSK, 16QAM, 64QAM, or 256QAM. In this case, the signal points on the constellation do not necessarily have to be equidistant. The constellation can be a non-uniform constellation (NUC). The transmission processing unit 211 multiplexes the modulation symbols and downlink reference signals for each channel and allocates the multiplexed signals to predetermined resource elements. Subsequently, the transmission processing unit 211 performs various types of signal processing on the multiplexed signals. For example, the transmission processing unit 211 performs processes such as using Fast Fourier Transform to convert to the frequency domain, adding a guard interval (cyclic prefix), generating a baseband digital signal, converting to an analog signal, quadrature modulation, upconversion, removing extra frequency components, and power amplification. The signal generated by the transmission processing unit 211 is transmitted from the antenna 213.

[0142] The receiving processing unit 212 processes the uplink signal received via antenna 213. For example, the receiving processing unit 212 performs processes on the uplink signal such as downconversion, removal of unwanted frequency components, amplification control, quadrature demodulation, conversion to a digital signal, removal of guard intervals (cyclic prefixes), and extraction of the domain signal using fast Fourier transform. Then, the receiving processing unit 212 demultiplexes the uplink channel (such as the Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH)) and the uplink reference signal in the signal that has undergone these processes. Subsequently, the receiving processing unit 212 demodulates the received signal using a modulation scheme such as Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK) for the modulation symbols of the uplink channel. The modulation scheme used in demodulation can be 16-QAM, 64QAM, or 256QAM. In this case, the signal points on the constellation do not necessarily have to be equidistant. The constellation can be a non-uniform constellation (NUC). Subsequently, the receiving and processing unit 212 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.

[0143] Antenna 213 is an antenna device that performs the conversion between current and radio waves. Antenna 213 may include one antenna element, such as a patch antenna. Alternatively, antenna 213 may include multiple antenna elements (e.g., multiple patch antennas). When antenna 213 includes multiple antenna elements, wireless communication unit 21 may have beamforming functionality. In this case, wireless communication unit 21 can use multiple antenna elements to control the directivity of radio signals to generate a directional beam. When antenna 213 includes multiple antenna elements, wireless communication unit 21 may have dot-forming functionality. In this case, wireless communication unit 21 can be configured to perform coordinated control of multiple antenna elements to form a dotted cell.

[0144] Antenna 213 can be a dual-polarized antenna. When antenna 213 is a dual-polarized antenna, wireless communication unit 21 can use vertically polarized waves (V-polarized waves) and horizontally polarized waves (H-polarized waves) (or dual-polarized waves in polarization directions at 45 degrees and -45 degrees to the vertical) for radio signal transmission. Wireless communication unit 21 can control the directivity of radio signals transmitted using vertically polarized waves and horizontally polarized waves (or dual-polarized waves in polarization directions at 45 degrees and -45 degrees to the vertical). Furthermore, wireless communication unit 21 can transmit and receive spatially multiplexed signals via multiple layers including multiple antenna elements.

[0145] Storage unit 22 is a readable / writable storage device such as DRAM, SRAM, flash memory, or hard disk. Storage unit 22 serves as a storage component in base station 20.

[0146] Control unit 23 is a controller that controls various parts of base station 20. Control unit 23 controls the wireless communication unit to perform wireless communication with another wireless communication device (e.g., relay station 30, terminal device 40, or another base station 20). Control unit 23 can be implemented by a processor such as a CPU or MPU. Specifically, control unit 23 can be implemented by a processor using RAM or similar memory as a workspace to execute various programs stored in a storage device within base station 20. Control unit 23 can be implemented by an integrated circuit such as an ASIC or FPGA. Control unit 23 can also be implemented by a GPU. CPU, MPU, ASIC, FPGA, and GPU can all be considered as controllers. Control unit 23 may include multiple physically separate objects. For example, control unit 23 may include multiple semiconductor chips.

[0147] The control unit 23 includes an acquisition unit 231, a forming unit 232, a tracking unit 233, a rollback unit 234, and a scheduling unit 235. Each block constituting the control unit 23 (acquisition unit 231 to scheduling unit 235) is a functional block that respectively instructs the function of the control unit 23. These functional blocks can be software blocks or hardware blocks. For example, each of the above functional blocks can be a software module implemented by software (including microprograms) or a circuit block on a semiconductor chip (die). Of course, each functional block can be formed into a processor or an integrated circuit. Note that the control unit 23 can be configured in a functional unit different from the above functional blocks. Functional blocks can be configured using any method.

[0148] In some embodiments, base station 20 may be configured as a collection of multiple physical or logical devices. As an example, base station 20 in this embodiment may be classified as multiple devices, such as baseband units (BBUs) and radio units (RUs). Base station 20 can be understood as a collection of multiple devices. Furthermore, the base station may be any one or both of a BBU and an RU. BBUs and RUs may be connected to each other via a predetermined interface (e.g., enhanced universal public radio interface (eCPRI)).

[0149] The RU can be referred to as a Remote Radio Unit (RRU) or Radio Point (RD). The RU can support the gNB Distributed Unit (gNB-DU) described below. The BBU can support the gNB Central Unit (gNB-CU) described below. The RU can be an antenna-integrated device. The antenna of base station 20, for example, an antenna integrated with the RU, can employ an advanced antenna system and support MIMO (e.g., FD-MIMO) or beamforming. Furthermore, the antenna of base station 20 can support point formation. For example, the antenna of base station 20 may include 64 transmit antenna ports and 64 receive antenna ports.

[0150] The antenna mounted on the RU can be an antenna panel comprising one or more antenna elements, and the RU can include one or more antenna panels. The RU can be equipped with two types of antenna panels: horizontally polarized antenna panels and vertically polarized antenna panels. The RU can also be equipped with two types of antenna panels: right-hand circularly polarized antenna panels and left-hand circularly polarized antenna panels, or antenna panels with a polarization direction at 45 degrees to the vertical direction and antenna panels with a polarization direction at -45 degrees to the vertical direction. Multiple antennas with multiple polarization directions can be mounted on a single antenna panel. The RU can form and control an independent beam for each antenna panel.

[0151] Multiple base stations 20 can be interconnected. One or more base stations 20 may be included in a radio access network (RAN). That is, base station 20 may be simply referred to as RAN, RAN node, access network (AN), AN node, etc. The RAN in LTE is sometimes called Enhanced Universal Terrestrial RAN (EUTRAN). The RAN in NR may be called NGRAN. In addition, the RAN in 6G may be called 6GRAN. The RAN in W-CDMA (UMTS) may be called UTRAN.

[0152] In LTE, base station 20 can be referred to as an evolved Node B (eNodeB) or eNB. That is, the EUTRAN includes one or more eNodeBs (eNBs). NR base station 20 can be referred to as a gNodeB or gNB. In this case, the NGRAN includes one or more gNBs. 6G base station can be referred to as a 6GNodeB, 6gNodeB, 6GNB, or 6gNB. In this case, the 6GRAN includes one or more 6GNBs. In an LTE communication system (EPS), the EUTRAN can include gNBs (en-gNBs) connected to the core network (EPC). In a 5G communication system (5GS), the NGRAN can include ng-eNBs connected to the core network 5GC.

[0153] When base station 20 is an eNB, gNB, 6GNB, etc., base station 20 can be referred to as a 3GPP access point. When base station 20 is a radio access point, base station 20 can be referred to as a non-3GPP access point. Base station 20 can be an optical link device referred to as a Remote Radio Header (RRH). Furthermore, when base station 20 is a gNB, base station 20 can be a combination of the aforementioned gNB-CU and gNB-DU, or it can be any one of gNB-CU and gNB-DU.

[0154] Here, for communication with the UE, the gNB-CU manages several upper layers in the access layer (e.g., Radio Resource Control (RRC), Serving Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP)). Conversely, the gNB-DU manages several lower layers in the access layer (e.g., Radio Link Control (RLC), Media Access Control (MAC), and Physical Layer (PHY)). That is, in the messages / information described below, RRC signaling (semi-static notification) can be generated by the gNB-CU, while MAC CE and DCI (dynamic notification) can be generated by the gNB-DU. Alternatively, for example, in RRC configuration (semi-static notification), some configurations such as IE:cellGroupConfig can be generated by the gNB-DU, while other configurations can be generated by the gNB-CU. These configurations can be transmitted and received via the F1 interface described below.

[0155] Base station 20 can be configured to communicate with another base station. When multiple base stations 20 are eNBs or a combination of eNB and en-gNB, these base stations 20 can be connected via the X2 interface. When multiple base stations 20 are gNBs or a combination of gn-eNB and gNB, these base stations 20 can be connected via the Xn interface. When multiple base stations 20 are a combination of gNB-CU and gNB-DU, these base stations 20 can be interconnected via the aforementioned F1 interface. For example, messages / information (e.g., RRC signaling, MAC control elements (MAC CE), downlink control information (DCI), etc.) described below can be transmitted between multiple base stations 20 via interfaces such as the X2 interface, Xn interface, and F1 interface.

[0156] The cell provided by base station 20 can be referred to as the serving cell. A serving cell conceptually includes a primary cell (PCell) and a secondary cell (SCell). When providing dual connectivity to terminal device 40, the PCell provided by the master control node (MN) and zero or more SCells can be referred to as a master control cell group (SCG). 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. Examples of dual connectivity also include NR-6G dual connectivity and 6G-NR dual connectivity.

[0157] Serving cells can include primary and secondary cells or primary SCG cells (PSCells). In providing dual connectivity for terminal device 40, the PSCell, along with zero or more SCells provided by the secondary node (SN), can be referred to as a secondary cell group (SCG). Unless specifically configured (e.g., PUCCH on the SCell), the Physical Uplink Control Channel (PUCCH) is transmitted by the PCell and PSCell, not by the SCell. Radio link failures are also detected by the PCell and PSCell, not by the SCell (which does not need to be detected). In this way, because the PCell and PSCell have a special role in the serving cell, these cells are also referred to as special cells (SpCells).

[0158] A cell can be associated with one downlink component carrier and one uplink component carrier. The system bandwidth corresponding to a cell can be divided into multiple bandwidth portions (BWPs). In this case, one or more BWPs can be configured for terminal device 40, and one BWP can be used as the active BWP of terminal device 40. The radio resources available to terminal device 40 (e.g., frequency bands, reference sets (subcarrier spacing), and time slot formats (time slot configurations)) can be different for each cell, each component carrier, or each BWP.

[0159] <2-3. Relay Station Configuration>

[0160] Relay station 30 is a wireless communication device that acts as a repeater for base station 20. Relay station 30 is a type of base station. Relay station 30 is a type of information processing device. Relay station 30 can also be referred to as a relay base station. For example, relay station 30 can be a device referred to as a repeater (e.g., an RF repeater, a smart repeater, or a smart surface). Relay station 30 is a wireless communication device that performs wireless communication with other wireless communication devices (e.g., base station 20, another relay station 30, or terminal device 40).

[0161] Relay station 30 can perform NOMA communication with terminal device 40. Relay station 30 relays communication between base station 20 and terminal device 40. Relay station 30 can perform wireless communication with another relay station 30 and base station 20. Relay station 30 can be a ground station device or a non-ground station device. Relay station 30 and base station 20 together constitute a radio access network (RAN).

[0162] The relay station 30 can be a fixed device, a mobile device, or a floating device. The size of the coverage area of ​​the relay station 30 is not limited to a specific size. The cell covered by the relay station 30 can be a macro cell, a micro cell, or a small cell.

[0163] The relay station 30 can be installed on any type of device, as long as it fulfills the relay function. The relay station 30 can be installed on terminal devices such as smartphones, on cars, trains or human-powered vehicles, on balloons, airplanes or drones, or on household appliances such as televisions, game consoles, air conditioners, refrigerators or lighting equipment.

[0164] The configuration of relay station 30 can be similar to that of base station 20 described above. Similar to base station 20, relay station 30 can be a device mounted on a mobile body, or it can be the mobile body itself. Here, as mentioned above, the mobile body can be a mobile terminal such as a smartphone or mobile phone. The mobile body can be a mobile body moving on land (narrowly defined as on the ground), or a mobile body moving within the ground. The mobile body can be a mobile body moving on the water surface, or a mobile body moving underwater. The mobile body can be a mobile body moving within the atmosphere, or a mobile body moving outside the atmosphere. Relay station 30 can be a ground station device or a non-ground station device. Relay station 30 can be an air station or a satellite station.

[0165] The coverage area of ​​relay station 30 can be large (e.g., macro cell) or small (e.g., pico cell), similar to base station 20. The coverage area of ​​relay station 30 can also be extremely small, such as femtocell. Relay station 30 can have beamforming capabilities. In this case, relay station 30 can form a cell or service area for each beam. Relay station 30 can also include point-forming capabilities. In this case, relay station 30 can form a cell or service area for each point.

[0166] Figure 10 This diagram illustrates the configuration of a relay station 30 according to this embodiment. The relay station 30 includes a wireless communication unit 31, a storage unit 32, and a control unit 33. Figure 10 The configuration shown is a functional configuration, and the hardware configuration may differ from this configuration. Furthermore, the functionality of relay station 30 can be implemented in a distributed manner across multiple physically separate configurations.

[0167] The wireless communication unit 31 is a signal processing unit for performing wireless communication with other wireless communication devices (e.g., base station 20, terminal device 40, or another relay station 30). The wireless communication unit 31 can support one or more radio access schemes. The wireless communication unit 31 can support at least one of NR, LTE, and 6G. In addition to NR, LTE, and 6G, the wireless communication unit 31 can also support W-CDMA, cdma3000, etc.

[0168] The wireless communication unit 31 includes a transmission processing unit 311, a receiving processing unit 312, and an antenna 313. The wireless communication unit 31 may include multiple transmission processing units 311, multiple receiving processing units 312, and multiple antennas 313. When the wireless communication unit 31 supports multiple radio access schemes, each part of the wireless communication unit 31 can be configured separately for each radio access scheme. The transmission processing unit 311 and the receiving processing unit 312 can be configured separately for LTE, NR, and 6G. The configuration of the transmission processing unit 311, the receiving processing unit 312, and the antenna 313 can be similar to the configuration of the transmission processing unit 211, the receiving processing unit 212, and the antenna 213 of the base station 20 described above. The wireless communication unit 31 may have beamforming functionality similar to that of the wireless communication unit 21 of the base station 20. The wireless communication unit 31 may have dot-forming functionality similar to that of the wireless communication unit 21 of the base station 20.

[0169] Storage unit 32 is a readable / writable storage device, such as DRAM, SRAM, flash memory, or hard disk. Storage unit 32 serves as a storage component in relay station 30. The configuration and function of storage unit 32 can be similar to those of storage unit 22 in base station 20 described above.

[0170] Control unit 33 is a controller that controls the various parts of relay station 30. Control unit 33 can be implemented by a processor such as a CPU or MPU. Specifically, control unit 33 is implemented by a processor using RAM or similar memory as its working area to execute various programs stored in storage devices within relay station 30. Control unit 33 can be implemented by an integrated circuit such as an ASIC or FPGA. CPU, MPU, ASIC, and FPGA can all be considered controllers. Control unit 33 can be implemented by a GPU. CPU, MPU, ASIC, FPGA, and GPU can all be considered controllers. Control unit 33 may include multiple physically separate objects. For example, control unit 33 may include multiple semiconductor chips. The configuration and function of control unit 33 can be similar to the configuration and function of control unit 23 of base station 20 described above.

[0171] The control unit 33 includes an acquisition unit 331, a forming unit 332, a tracking unit 333, a rollback unit 334, and a scheduling unit 335. Each block constituting the control unit 33 (acquisition unit 331 to scheduling unit 335) is a functional block that respectively instructs the function of the control unit 335. These functional blocks can be software blocks or hardware blocks. For example, each of the above functional blocks can be a software module implemented by software (including microprograms) or a circuit block on a semiconductor chip (die). Of course, each functional block can be formed into a processor or an integrated circuit. Note that the control unit 33 can be configured in a different functional unit than the above functional blocks. Functional blocks can be configured using any method.

[0172] Note that relay station 30 can be an IAB relay node. For IAB donor nodes providing backhaul, relay station 30 operates as an IAB mobile terminal (IAB-MT), while for terminal devices 40 providing access, relay station 30 operates as an IAB distributed unit (IAB-DU). For example, an IAB donor node can be base station 20, operating as an IAB central unit (IAB-CU).

[0173] <2-4. Configuration of Terminal Device>

[0174] Terminal device 40 is a wireless communication device that performs wireless communication with another wireless communication device (e.g., base station 20, relay station 30, or another terminal device 40, etc.). Terminal device 40 can be implemented using any form of information processing device (computer). For example, terminal device 40 can be a mobile terminal, such as a mobile phone, smart device (smartphone or tablet), personal digital assistant (PDA), or laptop PC. Terminal device 40 can be an imaging device with communication capabilities (e.g., a camcorder). Terminal device 40 can be a motorcycle, mobile relay vehicle, etc., equipped with a communication device such as a field pickup unit (FPU). Terminal device 40 can be a machine-to-machine (M2M) device or an Internet of Things (IoT) device. Terminal device 40 can be a wearable device, such as a smartwatch.

[0175] Terminal device 40 can be an xR device, such as an augmented reality (AR) device, a virtual reality (VR) device, or a mixed reality (MR) device. In this case, the xR device can 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 terminal device 40 is an xR device, it can be a standalone device, containing only the portion worn by the user (e.g., glasses). Alternatively, terminal device 40 can be a terminal-linked device, including the portion worn by the user (e.g., glasses) and a terminal portion (e.g., a smart device) linked to the portion worn by the user.

[0176] Terminal device 40 can perform NOMA communication with base station 20. When communicating with base station 20, terminal device 40 can use automatic repeater technology such as HARQ. Terminal device 40 can perform sidelink communication with another terminal device 40. When performing sidelink communication, terminal device 40 can use automatic repeater technology such as HARQ. When performing sidelink communication with another terminal device 40, terminal device 40 can perform NOMA communication. Terminal device 40 can perform LPWA communication with another wireless communication device (such as base station 20). The wireless communication used by terminal device 40 can be millimeter-wave wireless communication. The wireless communication used by terminal device 40 (including sidelink communication) can be radio wave wireless communication, or infrared or visible light wireless communication, i.e., optical wireless communication.

[0177] Terminal device 40 can be a portable wireless communication device, i.e., a mobile device. Alternatively, terminal device 40 can be a wireless communication device mounted on a mobile body, or it can be the mobile body itself. Terminal device 40 can be a vehicle moving on a road, such as a car, bus, truck, or motorcycle, or it can be a wireless communication device mounted on a vehicle. The mobile body can be a mobile terminal, or it can be a mobile body moving on land (narrowly defined as on the ground), in the ground, on water, or underwater. The mobile body can be a mobile body moving within the atmosphere, such as an airplane, airship, balloon, or helicopter, or it can be a mobile body moving outside the atmosphere, such as a satellite. The mobile body can be an unmanned aerial vehicle (UAV), such as a drone. Terminal device 40 can be a wireless communication device mounted on the mobile body.

[0178] Terminal device 40 can perform communication while simultaneously connecting to multiple base stations 20 or multiple cells. For example, when a base station 20 supports a communication area via multiple cells (e.g., pCell and sCell), it is possible to combine multiple cells and communicate between base station 20 and terminal device 40 using carrier aggregation (CA), dual connectivity (DC), or multiple connectivity (MC) technologies. Alternatively, terminal device 40 and multiple base stations 20 can communicate with each other via cells of different base stations 20 using coordinated multipoint transmission and reception (CoMP) technology.

[0179] Terminal device 40 may be a relay terminal that relays communication to a remote terminal.

[0180] Figure 11 This diagram illustrates 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, and a control unit 33. Figure 11The configuration shown is a functional configuration, and the hardware configuration may differ from this configuration. Furthermore, the functionality of the terminal device 40 can be implemented in a distributed manner across multiple physically separate configurations.

[0181] The wireless communication unit 41 is a signal processing unit used to perform wireless communication with other wireless communication devices (e.g., base station 20, relay station 30, and another terminal device 40). The wireless communication unit 41 is controlled by the control unit 43. The wireless communication unit 41 can support one or more radio access schemes. The wireless communication unit 41 can support at least one of NR, LTE, and 6G. In addition to NR, LTE, and 6G, the wireless communication unit 41 can also support W-CDMA, cdma2000, etc. The wireless communication unit 41 can support automatic repeater technologies, such as Hybrid Automatic Repeat Request (HARQ).

[0182] The wireless communication unit 41 includes a transmission processing unit 411, a receiving processing unit 412, and an antenna 413. The wireless communication unit 41 may include multiple transmission processing units 411, multiple receiving processing units 412, and multiple antennas 413. When the wireless communication unit 41 supports multiple radio access schemes, each part of the wireless communication unit 41 can be configured separately for each radio access scheme. The transmission processing unit 411 and the receiving processing unit 412 can be configured separately for LTE, NR, and 6G. The antenna 413 may include multiple antenna elements, such as multiple patch antennas. The wireless communication unit 41 may have beamforming capabilities. For example, the wireless communication unit 41 may have polarization beamforming capabilities using vertically polarized waves (V-polarized waves) and horizontally polarized waves (H-polarized waves) (or it may have dual-polarization beamforming capabilities using polarization directions at 45 degrees and -45 degrees to the vertical direction). The wireless communication unit 41 may also include dot formation capabilities.

[0183] Storage unit 42 is a readable / writable storage device such as DRAM, SRAM, flash memory, or hard disk. Storage unit 42 serves as a storage component in terminal device 40.

[0184] Control unit 43 is a controller that controls various parts of terminal device 40. Control unit 43 controls the wireless communication unit to perform wireless communication with another wireless communication device (e.g., base station 20, relay station 30, or another terminal device 40). Control unit 43 can be implemented by a processor such as a CPU or MPU. Specifically, control unit 43 is implemented by a processor using RAM or the like as a working area to execute various programs stored in a storage device within terminal device 40. Control unit 43 can be implemented by an integrated circuit such as an ASIC or FPGA. CPU, MPU, ASIC, and FPGA can all be considered controllers. Control unit 43 can be implemented by a GPU. CPU, MPU, ASIC, FPGA, and GPU can all be considered controllers. Control unit 43 may include multiple physically separate objects. For example, control unit 43 may include multiple semiconductor chips.

[0185] The control unit 43 includes an acquisition unit 431, a transmission unit 432, and a communication control unit 433. The various blocks constituting the control unit 43 (acquisition unit 431 to communication control unit 433) are functional blocks that respectively indicate the functions of the control unit 43. These functional blocks can be software blocks or hardware blocks. For example, each of the above functional blocks can be a software module implemented through software (including microprograms) or a circuit block on a semiconductor chip (die). Of course, each functional block can be formed into a processor or an integrated circuit. Note that the control unit 43 can be configured in a different functional unit than the above functional blocks. Functional blocks can be configured using any method.

[0186] <<3. Basic Operations of Communication Systems>>

[0187] The configuration of communication system 1 has been described above. Before describing the operation of communication system 1 used to solve the problems of this embodiment, the basic operation of communication system 1 will be described.

[0188] In the following description, base station 20 may be referred to as a gateway. Furthermore, base station 20 may be read as relay station 30.

[0189] <3-1. Initial Connection Processing>

[0190] First, the initial connection process will be described.

[0191] The initial connection process is used to transition the radio connection state of terminal device 40 from an unconnected state to a connected state. Unconnected states include, for example, RRC_IDLE and RRC_INACTIVE. RRC_IDLE is an idle state where the terminal device is not connected to any cell, and is also called idle mode. RRC_INACTIVE is a radio connection state newly defined in NR that indicates inactivity, and is also called inactive mode. Under RRC_INACTIVE, no RRC connection is established between terminal device 40 and the base station, but terminal device 40 and the base station can each maintain some state of saved UE context. Terminal device 40 and the base station can use the saved UE context to accelerate repeated transitions of terminal device 40 to the connected state. Unconnected states can include Lightning mode. Examples of connected states include RRC_CONNECTED. RRC_CONNECTED is a connected state where the terminal device has established a connection with a specific cell (e.g., the primary cell), and is also called CONNECTED mode.

[0192] Figure 12 This is a flowchart illustrating an example of the initial connection processing. See below for reference. Figure 12 Describe the initial connection process. For example, the following initial connection process is performed when the terminal device 40 is powered on.

[0193] First, the terminal device 40, which is in a disconnected state, performs a cell selection process (cell search). The cell selection process (cell search) is the process by which the user equipment (UE) detects the physical cell ID (PCI) of a cell and obtains time and frequency synchronization. In this embodiment, the cell search includes the steps of detecting a synchronization signal and decoding the physical broadcast channel (PBCH). The terminal device 40 detects the cell's synchronization signal (step S11).

[0194] Terminal device 40 performs downlink synchronization with the cell based on the detected synchronization signal. Subsequently, after establishing downlink synchronization, terminal device 40 attempts to decode the PBCH and obtain the Master Control Information Block (MIB) as part of the system information (step S12).

[0195] System information is information announced and set up within a cell from which it transmits system information. System information can be information shared by all terminal devices (including terminal device 40) belonging to that cell. System information can also be cell-specific. System information includes, for example, information about the access cell, information about cell selection, and information about other RATs and other systems. System information includes MIBs and System Information Blocks (SIBs). MIBs are information required to receive SIBs, etc., and are information of a fixed payload size announced by the PBCH. MIBs include a portion of the system frame number, at least SIB1 and Msg. 2 / 4 information on subcarrier spacing for initial connection and paging and broadcast SI messages, subcarrier offset information, DMRS Type A location information, at least PDCCH configuration for SIB1, cell blocking (cell blocking) information, and intra-frequency reselection information. SIBs are system information other than MIBs and are announced by the PDSCH.

[0196] System information can be categorized into first system information, second system information, and third system information. First and second system information include information about the access cell, information about obtaining other system information, and information about cell selection. Information included in the MIB is first system information. Information included in SIB1 within the SIB is second system information (e.g., the remaining minimum SI). The remaining system information is third system information (e.g., other SIs).

[0197] Furthermore, in NR, system information is announced from the NR cell. The physical channel carrying the system information can be transmitted in time slots or micro-time slots. A micro-time slot is defined by the number of symbols, which is less than the number of symbols in a time slot. Because the physical channel carrying the system information is transmitted in micro-time slots, it is possible to reduce the time required for beam scanning, thereby reducing overhead. In NR, the first system information is transmitted on the NR-PBCH, and the second system information is transmitted on a different physical channel than the NR-PBCH.

[0198] Terminal device 40 obtains second system information based on MIB (i.e., first system information) (step S13). As described above, the second system information includes SIB1 and SIB2.

[0199] SIB1 includes cell access control information and scheduling information about system information other than SIB1. In the NR case, SIB1 includes information about cell selection (e.g., cellSelectionInfo), cell access information (e.g., cellAccessRelatedInfo), connection establishment failure control information (e.g., connEstFailureControl), scheduling information about system information other than SIB1 (e.g., si-SchedulingInfo), and serving cell settings. Serving cell configuration includes cell-specific parameters and includes downlink configuration, uplink configuration, and TDD configuration information. Uplink settings include RACH settings, etc. Furthermore, in the LTE case, SIB1 includes cell access information, cell selection information, maximum uplink transmission power information, TDD configuration information, system information period, system information mapping information, and system information (SI) window length.

[0200] In the NR scenario, SIB2 includes cell reselection information (e.g., cellReselectionInfoCommon) and cell reselection serving frequency information (e.g., cellReselectionServingFreqInfo). In the LTE scenario, SIB2 includes connection prohibition information, cell-shared radio resource configuration information (radioResourceConfigCommon), and uplink carrier information. The cell-shared radio resource configuration information includes configuration information regarding the cell-shared Physical Random Access Channel (PRACH) and Random Access Channel (RACH).

[0201] When terminal device 40 fails to obtain the system information required for link establishment, terminal device 40 determines that cell access is prohibited. For example, if obtaining the first system information fails, terminal device 40 determines that cell access is prohibited. In this case, terminal device 40 terminates the initial connection process.

[0202] When system information has been successfully acquired, the terminal device 40 executes a random access procedure (steps S14 to S17) based on the first system information and / or the second system information. The random access procedure may be referred to as the Random Access Channel procedure (RACH procedure) or the RA procedure.

[0203] The random access procedure includes the following steps: transmitting the random access preamble (step S14), receiving the random access response (step S15), transmitting message 3 (step S16), and receiving contention resolution (step S17).

[0204] First, terminal device 40 selects a predetermined Physical Random Access Channel (PRACH) preamble and transmits the selected preamble to base station 20 (step S14). Next, terminal device 40 receives the Physical Downlink Shared Channel (PDSCH) including the random access response corresponding to the PRACH preamble (step S15). Next, terminal device 40 uses resources scheduled by the random access response grant included in the random access response to transmit the PUSCH including message 3 (step S16). Finally, terminal device 40 receives the PDSCH containing contention resolution corresponding to the PUSCH (step S17).

[0205] Message 3 includes a Radio Resource Control (RRC) message requesting an RRC connection. Contention resolution includes an RRC message for RRC connection setup. Upon receiving an RRC connection setup RRC message, terminal device 40 performs an RRC connection operation and transitions from an RRC idle state to an RRC connected state. After transitioning to the RRC connected state, terminal device 40 transmits an RRC message to base station 20 indicating that the RRC connection setup is complete. This series of operations allows terminal device 40 to connect to base station 20.

[0206] The random access preamble can be represented as message 1, the random access response can be represented as message 2, the contention resolution can be represented as message 4, and the RRC connection setup complete message can be represented as message 5.

[0207] After all steps of the random access procedure are completed, the terminal device 40 can switch to the state of being connected to the cell (connected state).

[0208] Notice, Figure 12 The random access procedure in this process can be referred to as a 4-step random access procedure (4-step RACH procedure). On the other hand, the random access procedure in which the terminal device 40 transmits message 3 along with the random access preamble, and the base station 20 transmits a random access response and contention resolution in response to the received message, can be referred to as a 2-step random access procedure (2-step RACH procedure).

[0209] <3-2. Random Access Procedure>

[0210] The random access process will be described in detail below.

[0211] Random access procedures are performed for purposes such as "RRC connection setup" to transition from an idle state to a connected state (or inactive state), and "request for state transition" to transition from an inactive state to a connected state. Random access procedures are also used to make "scheduling requests" for resources used for uplink data transmission and "timing advance adjustments" to adjust uplink synchronization. Furthermore, random access procedures are also performed in situations such as "on-demand SI requests" for requesting system information that has not yet been transmitted, "beam recovery" to restore interrupted beam connections, and "handover" to switch connected cells.

[0212] "RRC connection setup" is an operation performed when terminal device 40 connects to base station 20 in association with traffic generation, etc. Specifically, this operation involves transferring connection-related information (e.g., UE context) from base station 20 to terminal device 40. The UE context is managed by predetermined communication device identification information (e.g., C-RNTI) indicated by base station 20. After this operation is completed, terminal device 40 performs a state transition from idle state to inactive state or from idle state to connected state.

[0213] A "request for state transition" is an operation by which terminal device 40 requests a state transition from an inactive state to a connected state, which is associated with traffic generation and other similar activities. After transitioning to the connected state, terminal device 40 can transmit unicast data to and receive unicast data from base station 20.

[0214] A "scheduling request" is an operation performed by the terminal device 40 in association with traffic generation and other related activities, requesting resources for uplink data transmission. Upon receiving a scheduling request normally, the base station 20 assigns PUSCH resources to the communication device. This scheduling request is also executed via PUCCH.

[0215] "Timing advance adjustment" is an operation used to adjust for the error between downlink and uplink frames caused by propagation delay. Terminal device 40 transmits the adjusted downlink frame via the Physical Random Access Channel (PRACH). This allows base station 20 to identify the propagation delay with terminal device 40 and indicate the timing advance value to terminal device 40 via message 2, etc.

[0216] "On-demand SI request" is an operation in which the terminal device 40 requests the base station 20 to transmit system information when it needs system information that has not been transmitted due to system information overhead, etc.

[0217] "Beam recovery" is an operation that requests restoration of communication quality after beam establishment, caused by the movement of terminal device 40 or the interruption of the communication path by another object. Upon receiving this request, base station 20 attempts to connect to terminal device 40 using a different beam.

[0218] "Handover" is the operation of switching the connection from the cell (serving cell) to which the terminal device 40 is connected to to a neighboring cell (neighboring cell) due to a change in the radio wave environment, such as the movement of the terminal device 40. After receiving a handover command from the base station 20, the terminal device 40 makes a connection request to the neighboring cell specified by the handover command.

[0219] Random access procedures include contention-based random access procedures and non-contention-based random access procedures.

[0220] The random access procedure described below assumes that the RAT supported by communication system 1 is LTE. However, the random access procedure described below also applies to situations where the RAT supported by communication system 1 is a technology other than LTE.

[0221] <3-2-1. Contention-Based Random Access Procedure>

[0222] First, the contention-based random access procedure will be described. The contention-based random access procedure is a random access procedure actively executed by the terminal device 40. Figure 13 This is a diagram illustrating a contention-based random access process. (Example) Figure 13 As shown, the contention-based random access procedure is a four-step process that begins with the terminal device 40 transmitting the random access preamble. The contention-based random access procedure includes the following steps: transmitting the random access preamble (message 1), receiving the random access response (message 2), transmitting a message (message 3), and receiving a message for resolving the contention (message 4).

[0223] First, the terminal device 40 randomly selects a preamble sequence to be used from a plurality of predetermined preamble sequences. Then, the terminal device 40 transmits a message (Message 1: Random Access Preamble) including the selected preamble sequence to the base station 20, which is the connection destination (step S21). The random access preamble is transmitted on the PRACH.

[0224] Upon receiving the random access preamble, base station 20 transmits a random access response (message 2) to terminal device 40, which is a reply to the random access preamble. For example, this random access response is transmitted using a PDSCH. Terminal device 40 receives the random access response (message 2) transmitted from base station 20 (step S22). The random access response includes one or more random access preambles that base station 20 has successfully received, and the uplink (UL) resources (hereinafter referred to as uplink grants) corresponding to the random access preamble. The random access response includes a Temporary Cell Radio Network Temporary Identifier (TC-RNTI), which is a unique identifier temporarily assigned to terminal device 40 by base station 20.

[0225] Upon receiving a random access response from base station 20, terminal device 40 determines whether the received information includes the random access preamble transmitted in step S21. If the random access preamble is included, terminal device 40 extracts the uplink grant corresponding to the random access preamble transmitted in step S21 from the uplink grant included in the random access response. Subsequently, terminal device 40 uses the resource transmission UL message (Message 3: Scheduled Transmission) scheduled by the extracted uplink grant (step S23). The transmission of message (Message 3) is performed using PUSCH. Message (Message 3) includes an RRC message for a Radio Resource Control (RRC) connection request. Message (Message 3) also includes an identifier of terminal device 40. Message (Message 3) can be represented as "Msg3".

[0226] In a contention-based random access process, a random access preamble randomly selected by terminal device 40 is used. Therefore, it is possible for terminal device 40 to transmit a random access preamble while another terminal device 40 transmits the same random access preamble to base station 20. Therefore, by receiving the identifier transmitted by terminal device 40 in step S23, base station 20 identifies the location where preamble contention occurs between the terminal devices to resolve the contention. Base station 20 transmits a contention resolution message (message 4) to the terminal device 40 selected through contention resolution. The contention resolution message (message 4) includes the identifier transmitted by terminal device 40 in step S23. The contention resolution message (message 4) also includes an RRC connection setting RRC message. Terminal device 40 receives the contention resolution message (message 4) transmitted from base station 20 (step S24).

[0227] Terminal device 40 compares the identifier transmitted in step S23 with the identifier received in step S24. If the identifiers do not match, terminal device 40 retryes the random access procedure from step S21. If the identifiers match, terminal device 40 performs an RRC connection operation and transitions from the idle state (RRC_IDLE) to the connected state (RRC_CONNECTED). Terminal device 40 uses the TC-RNTI obtained in step S22 as the cell radio network temporary identifier (C-RNTI) in subsequent communications. After transitioning to the connected state, terminal device 40 transmits an RRC message indicating that the RRC connection setup is complete to base station 20. The RRC connection setup complete message is also referred to as message 5. Through this series of operations, terminal device 40 connects to base station 20.

[0228] Figure 13The contention-based random access procedure shown is a four-step random access procedure (4-step RACH). However, communication system 1 can also support a two-step random access procedure (2-step RACH) as a contention-based random access procedure. For example, terminal device 40 transmits the message (message 3) described in step S23 simultaneously with the random access preamble. Subsequently, base station 20 transmits a random access response (message 2) and a contention resolution (message 4) as responses. Since the random access procedure is completed in two steps, terminal device 40 can quickly connect to base station 20.

[0229] <3-2-2. Non-contention-based random access procedure>

[0230] Next, we will describe the contention-free random access procedure. The contention-free random access procedure is a random access procedure actively executed by the base station. Figure 14 This diagram illustrates a contention-free random access procedure. The contention-free random access procedure is a three-step process that begins with the assignment of a random access preamble by base station 20. The contention-free random access procedure includes the following steps: receiving the random access preamble assignment (message 0), transmitting the random access preamble (message 1), and receiving the random access response (message 2).

[0231] In a contention-based random access process, terminal device 40 randomly selects a preamble sequence. However, in a non-contention-based random access process, base station 20 assigns a separate random access preamble to terminal device 40. Terminal device 40 receives the random access preamble assignment from base station 20 (message 0: RA preamble assignment) (step S31).

[0232] Terminal device 40 performs random access to base station 20 by using the random access preamble assigned in step S31. That is, terminal device 40 transmits the assigned random access preamble (message 1) to base station 20 via PRACH (step S32).

[0233] Base station 20 receives a random access preamble from terminal device 40 (message 1). Subsequently, base station 20 transmits a random access response (message 2) to terminal device 40 in response to the random access preamble (step S33). The random access response includes, for example, uplink grant information corresponding to the received random access preamble. After receiving the random access response (message 2), terminal device 40 performs an RRC connection operation and transitions from an idle state (RRC_IDLE) to a connected state (RRC_CONNECTED).

[0234] In this way, base station 20 schedules random access preambles during a non-contention-based random access process, thereby suppressing preamble contention.

[0235] <3-3. Details of the random access process in NR>

[0236] The above describes the random access procedure assuming that the RAT supported by communication system 1 is LTE. The above random access procedure also applies to RATs other than LTE. Below, the random access procedure assuming that the RAT supported by communication system 1 is NR will be described in detail. In the following description, details regarding... Figure 13 or Figure 14 The four steps of messages 1 through 4 are shown. The steps of message 1 are similar to... Figure 13 Step S21 and shown Figure 14 The steps shown correspond to S32. The steps in message 2 are the same as... Figure 13 Step S22 and shown Figure 14 The steps shown correspond to S33. The steps in message 3 are the same as... Figure 13 The steps shown correspond to S23. The steps in message 4 are the same. Figure 13 The step S24 shown corresponds to this.

[0237] NR random access preamble (message 1)

[0238] In NR, PRACH is called the NR Physical Random Access Channel (NR-PRACH). NR-PRACH is configured using the Zadoff-Chu sequence. In NR, various preamble formats are defined as NR-PRACH formats. The preamble format is defined by a combination of PRACH parameters, such as subcarrier spacing, transmission bandwidth, sequence length, number of symbols used for transmission, number of transmission repetitions, cyclic prefix (CP) length, and guard period. The types of NR-PRACH preamble sequences are numbered. These preamble sequence type numbers are represented as preamble indices.

[0239] In NR, NR-PRACH settings are performed on the idle terminal device 40 via system information. Additionally, NR-PRACH settings are performed on the connected terminal device 40 via dedicated RRC signaling.

[0240] Terminal device 40 uses physical resources (NR-PRACH timing) that can be transmitted via NR-PRACH to transmit NR-PRACH. The physical resources are indicated by settings regarding NR-PRACH. Terminal device 40 selects one of the physical resources to transmit NR-PRACH. Furthermore, when terminal device 40 is in a connected state, terminal device 40 uses NR-PRACH resources to transmit NR-PRACH. NR-PRACH resources are a combination of the NR-PRACH preamble and its physical resources. Base station 20 can indicate NR-PRACH resources to terminal device 40.

[0241] Note that NR-PRACH is transmitted even when the random access procedure fails. When NR-PRACH is retransmitted, terminal device 40 suspends NR-PRACH transmission for a pause period calculated based on a backoff value (backoff indicator, BI). The backoff value can vary depending on the terminal device 40's terminal category and the priority of the generated traffic. At this time, multiple backoff values ​​are provided, and terminal device 40 selects the one to use based on priority. Furthermore, when NR-PRACH is retransmitted, terminal device 40 increases the NR-PRACH transmission power compared to the initial transmission. This process is referred to as power ramping.

[0242] NR Random Access Response (Message 2)

[0243] NR random access responses are transmitted using the NR Physical Downlink Shared Channel (NR-PDSCH). The NR-PDSCH including the random access response is scheduled by the NR Physical Downlink Control Channel (NR-PDCCH), where Cyclic Redundancy Check (CRC) has been scrambled using RA-RNTI. The NR-PDCCH is transmitted on the Control Resource Set (CORESET). The NR-PDCCH with a CRC scrambled by RA-RNTI is placed in the Common Search Space (CSS) of the Type 1-PDCCH CSS set. The value of RA-RNTI (Random Access Radio Network Temporary Identifier) ​​is determined based on the transmission resources of the NR-PRACH corresponding to the random access response. The transmission resources of the NR-PRACH are, for example, time resources (time slots or subframes) and frequency resources (resource blocks). The NR-PDCCH can be placed in the search space associated with the NR-PRACH associated with the random access response. Specifically, the search space in which the NR-PDCCH is placed is set in association with the preamble of the NR-PRACH and / or the physical resources used to transmit the NR-PRACH. The search space in which the NR-PDCCH is placed is set in association with the preamble index and / or the index of the physical resources. The NR-PDCCH includes the NR-SS (NR synchronization signal) and the QCL (quasi-co-location).

[0244] The NR random access response is Media Access Control (MAC) information. It includes at least an uplink grant for transmitting NR message 3, a timing advance value for adjusting uplink frame synchronization, and a TC-RNTI value. The NR random access response includes a PRACH index for the corresponding NR-PRACH transmission. Furthermore, it includes backoff information for suspending PRACH transmission.

[0245] Base station 20 transmits a random access response on the NR-PDSCH. Based on the information included in the random access response, terminal device 40 determines whether the random access preamble has been successfully transmitted. When it is determined that the random access preamble has been successfully transmitted, terminal device 40 performs the transmission processing of NR message 3 according to the information included in the random access response. In contrast, when the transmission of the random access preamble fails, terminal device 40 determines that the random access process has failed and performs NR-PRACH retransmission processing.

[0246] The NR random access response may include multiple uplink grants for transmitting NR message 3. Terminal device 40 can select one resource from these uplink grants to transmit message 3. This mitigates conflicts in the transmission of NR message 3 if different terminal devices 40 receive the same NR random access response. Therefore, communication system 1 can provide a more stable random access procedure.

[0247] NR Message 3

[0248] NR message 3 is transmitted via the NR Physical Uplink Shared Channel (NR-PUSCH). The NR-PUSCH is transmitted using resources indicated by the random access response. NR message 3 includes an RRC connection request message. The format of the NR-PUSCH is indicated by parameters included in the system information. For example, this parameter determines which NR-PUSCH format to use: Orthogonal Frequency Division Multiplexing (OFDM) or Discrete Fourier Transform Spread Spectrum OFDM (DFT-s-OFDM).

[0249] When NR message 3 is received normally, base station 20 continues the contention resolution transmission process (message 4). In contrast, when NR message 3 is not received normally, base station 20 retryes receiving NR message 3 for at least a predetermined period of time.

[0250] Another example of instructions for retransmitting message 3 and transmission resources includes instructions made via the NR-PDCCH to instruct the retransmission of message 3. The NR-PDCCH is an uplink grant. The downlink control information (DCI) of the NR-PDCCH indicates the resources for retransmitting message 3. The terminal device 40 retransmits message 3 based on the instructions of the uplink grant.

[0251] If a contention resolution instruction for NR is not successfully received within a predetermined time period, the terminal device 40 considers the random access procedure to have failed and executes NR-PRACH retransmission processing. The transmission beam of the terminal device 40 used for retransmitting NR message 3 may be different from the transmission beam of the terminal device 40 used for the initial transmission of message 3. If neither an NR contention resolution instruction nor a message 3 retransmission instruction is received within the predetermined time period, the terminal device 40 considers the random access procedure to have failed and executes NR-PRACH retransmission processing. The predetermined time period is, for example, set by system information.

[0252] NR contention resolution (Message 4)

[0253] NR contention resolution is transmitted using NR-PDSCH. The NR-PDSCH containing contention resolution is scheduled by NR-PDCCH, where the CRC is scrambled by TC-RNTI or C-RNTI. The NR-PDCCH with a CRC scrambled by TC-RNTI is placed in the CSS of the Type 1-PDCCH CSS set. The NR-PDCCH can be placed in a user equipment-specific search space (USS). Note that the NR-PDCCH can be placed in a separate CSS.

[0254] When a contention-resolved NR-PDSCH is received normally, the terminal device 40 transmits an acknowledgment (ACK) response to the base station 20. Thereafter, the terminal device 40 considers the random access procedure successful and proceeds to the connected state (RRC_CONNECTED). Conversely, if a negative acknowledgment (NACK) is received from the terminal device 40 for the NR-PDSCH, or if no response is received, the base station 20 retransmits the contention-resolved NR-PDSCH. If no NR contention resolution (message 4) is received within a predetermined time period, the terminal device 40 considers the random access procedure to have failed and performs a retransmission of the random access preamble (message 1).

[0255] <3-4. Two-step RACH in NR>

[0256] Next, an example of the 2-step RACH procedure (hereinafter referred to as the 2-step random access procedure) in NR will be described. Figure 15 This is a diagram illustrating a two-step random access procedure. The two-step random access procedure consists of two steps: message A (step S41) and message B (step S42). As an example, message A includes message 1 (preamble) and message 3 from a standard four-step random access procedure (four-step RACH procedure), while message B includes messages 2 and 4 from a standard four-step random access procedure. Furthermore, as an example, message A includes a preamble (also called PRACH) and PUSCH, and message B includes PDSCH.

[0257] By employing a two-step random access procedure, the random access process can be completed with lower latency compared to the conventional four-step random access procedure.

[0258] The preamble and PUSCH included in message A can be set in association with each transport resource, or they can be set through a separate resource.

[0259] When configuring various transmission resources in association, and when determining the transmission resource for the preamble, for example, the PUSCH transmission resource is determined as a unique resource, or multiple candidate transmission resources are determined. As an example, the time and frequency offset between the preamble of the PRACH timing and the PUSCH timing is defined by a single value. As another example, the time and frequency offset between the preamble of the PRACH timing and the PUSCH timing is set to a different value for each preamble. The value of the offset can be determined by the specification, or it can be semi-statically set by the base station 20. As an example, the value of the time and frequency offset is defined by, for example, a predetermined frequency. For example, in an unlicensed frequency band (e.g., the 5 GHz band, band 45), the value of the time offset can be set to 0 or a value close to 0. Under this setting, Listen-Before-Speak (LBT) can be omitted before transmitting the PUSCH.

[0260] On the other hand, when transmission resources are set as independent resources, the transmission resources for the preamble and PUSCH can be determined separately in the specification, or the resources can be semi-statically set by the base station 20, or determined based on other information. Examples of other information include slot format information (e.g., slot format indicator), bandwidth portion (BWP) information, preamble transmission resource information, slot index, and resource block index. Furthermore, when set with independent resources, the association between the preamble and PUSCH constituting a message A can be provided to the base station via the PUSCH payload or the UCI included in the PUSCH, or this association can be provided to the base station 20 via PUSCH transmission physical parameters (e.g., PUSCH scrambling sequence, DMRS sequence, and / or mode, or PUSCH transmission antenna port).

[0261] The method for setting the transmission resources for the preamble and PUSCH can switch between setting them through interrelated configurations and setting them using independent resources. For example, in licensed bands, setting them using individual resources is allowed, while in unlicensed bands, setting them using interrelated transmission resources is allowed.

[0262] <<4. Operation of the Communication System>>

[0263] The basic operation of the communication system has been described above. Next, the operation of the communication system 1 in this embodiment will be described in detail below.

[0264] In the following embodiments, the base station 20 can be not only a ground station (ground base station), but also a non-ground station (non-ground base station) that operates as a communication device, such as a satellite station, drone, balloon or airplane.

[0265] In this embodiment, the resource indicates frequency, time, resource elements (including REG, CCE, CORESET), resource block, bandwidth portion, component carrier, symbol, sub-symbol, time slot, micro-time slot, sub-time slot, subframe, frame, PRACH timing, timing, code, multiple access physical resources, multiple access signature, and subcarrier spacing (digitalization), etc.

[0266] In this embodiment, the technique for locally forming cells is referred to as point formation, but the term is not limited thereto. Furthermore, in the following description, the communicable area formed by point formation is referred to as a point cell, but the term is not limited thereto.

[0267] Furthermore, in this embodiment, the point cell for switching to track the terminal device 40 or the point cell for performing a movement operation to track the terminal device 40 is referred to as a terminal tracking cell, but the terminology is not limited thereto.

[0268] As described above, base station 20 performs coordinated control of multiple antennas to concentrate power at a specific point, thereby forming a point cell. That is, base station 20 can form a point cell through the point formation function.

[0269] Here, point formation can be characterized as the initial phases of the transmitting antenna elements being different when power is concentrated at a specific point. On the other hand, beamforming can be characterized as the initial phase offsets of the transmitting antenna elements being the same when the beam is formed in a specific direction.

[0270] Normally, base station 20 forms a pre-designed cell and communicates with terminal devices 40 within that cell. That is, the design of a conventional cell takes into account its coverage area to provide communication in a specific region. However, in cases where advanced spatial multiplexing is achieved through point formation, the cell coverage differs from that of conventional technologies. In this situation, continued use of conventional cell handover procedures (e.g., conventional handover processes) can cause various problems, such as communication delays due to frequent handover procedures.

[0271] Therefore, in this embodiment, the base station 20 forms a cell for tracking the terminal device 40 as a new cell capable of supporting point formation. The terminal tracking cell differs from a conventional pre-designed cell and is dynamically generated to provide communication for a specific terminal device 40. In this case, the terminal tracking cell can be a cell dedicated to a specific terminal device 40 (hereinafter, this cell is also referred to as a dedicated cell). When the terminal tracking cell is a dedicated cell, the communication system 1 can provide communication dedicated to the specific terminal device 40.

[0272] <4-1. Example of Terminal Tracking Cell Formation>

[0273] The terminal tracking cell can be formed by either type 1 or type 2. Of course, the terminal tracking cell can be formed by any means other than type 1 and type 2.

[0274] (1) Type 1

[0275] Figure 16 This diagram illustrates a terminal tracking cell formation method according to Type 1. In Type 1, base station 20 forms multiple point cells PCs covering an area surrounded by transmission antennas. Figure 16 In the example, base station 20 forms m×m point cells PC (point cells PC) covering an area surrounded by transmission antennas. 11 To PC mn Base station 20 and terminal device 40 switch the point cell PC to which terminal device 40 is connected in order to track terminal device 40 moving in that area. Figure 16 In the example, base station 20 and terminal device 40 move according to point cell PC. 65 , point community PC 75 , point community PC 93 Hedian Community PC 94 The order of switching terminal device 40 is connected to the point community PC.

[0276] (2) Type 2

[0277] Figure 17This diagram illustrates a terminal tracking cell formation method according to Type 2. In Type 2, base station 20 dynamically changes the setting value of the point cell PC to track the movement of terminal device 40. That is, in Type 2, base station 20 dynamically moves the point cell PC to track the movement of terminal device 40. For example, when terminal device 40 connects to point cell PC1, base station 20 moves point cell PC1 to track the movement of terminal device 40. When terminal device 40 connects to point cell PC2, base station 20 moves point cell PC2 to track the movement of terminal device 40. In Type 2, after the initial connection between terminal device 40 and base station 20, the point cell PC moves according to the movement of terminal device 40. Therefore, terminal device 40 does not need to re-establish the initial connection through movement.

[0278] <4-2. Information used to form a terminal tracking cell>

[0279] Base station 20 can acquire information about terminal device 40 when forming a terminal tracking cell. Subsequently, base station 20 can perform processing (type 1 or type 2 processing) for enabling the point cell PC to track the terminal device based on the information about the terminal device. The information about the terminal device may include at least one of the following pieces of information (A1) to (A7):

[0280] (A1) Direction of movement of terminal device 40

[0281] (A2) Moving speed of terminal device 40

[0282] (A3) Absolute position information of terminal device 40

[0283] (A4) Relative position information of terminal device 40

[0284] (A5) Interference power information received by terminal device 40 belonging to the terminal tracking cell.

[0285] (A6) Information related to near or far field

[0286] (A7) Mobility scheduling information (including route information) of terminal device 40

[0287] Regarding the relative position information of terminal device 40 in (A4), the reference position (a position equivalent to the position of terminal device 40) used for calculating the relative position can be the connection start position with base station 20, the position of a specific base station 20, or a reference position provided by base station 20. Of course, the reference position can also be a position other than these.

[0288] <4-3. Exemplary Operations Related to Terminal Tracking>

[0289] In the following text, exemplary operation of the base station 20 and the terminal device 40 in relation to terminal tracking will be described.

[0290] <4-3-1. Time Period During which Terminal Tracking Cells Can Be Used>

[0291] After a terminal tracking cell is formed, the terminal device 40 can be configured such that the terminal tracking cell will remain available until certain conditions are met. Examples of these specific conditions include the following examples (B1) to (B3).

[0292] (B1) Until the effective timer for the terminal tracking cell expires.

[0293] (B2) Until the handover forms the transmission panel of the terminal tracking cell

[0294] (B3) Until it moves to base station 20 where it cannot form a terminal tracking cell.

[0295] When the state of terminal device 40 changes from a state where the terminal tracking cell is available to a state where the terminal tracking cell is unavailable, terminal device 40 can perform initial access again to attempt to connect to base station 20. Alternatively, when the state of terminal device 40 changes from a state where the terminal tracking cell is available to a state where the terminal tracking cell is unavailable, base station 20 can perform a fallback from the terminal tracking cell to a regular cell and reconnect to terminal device 40.

[0296] <4-3-2. Obtaining Information Required for Terminal Tracking>

[0297] Terminal device 40 (e.g., transmission unit 432 of terminal device 40) may periodically or dynamically notify base station 20 of information required for terminal tracking (information for forming a terminal tracking cell). The information required for terminal tracking may be the information shown in (A1) to (A7) above.

[0298] <Measuring Implementation Methods>

[0299] Terminal device 40 can acquire this information (the information required for terminal tracking) through measurement. At this time, the measurement of terminal device 40 can be performed periodically or non-periodically.

[0300] (Periodic implementation method)

[0301] For example, the terminal device 40 can perform measurements at predetermined time intervals. In this case, the measurement execution period can be a combination of multiple time periods. In addition, the terminal device 40 can continuously perform measurements at regular intervals.

[0302] (Non-periodic implementation method)

[0303] For example, terminal device 40 can perform measurements based on event triggering. For example, terminal device 40 can perform measurements at a time when it receives a measurement execution request from base station 20. Terminal device 40 can measure a pre-provided or determined measurement execution trigger notification and perform measurements at a time when the trigger is activated. In this case, the trigger can be one of the following (C1) to (C4).

[0304] (C1) The scheduled time of arrival

[0305] (C2) The communication quality indicator standard (e.g., a predetermined threshold) of the cell to which terminal device 40 belongs, or a timing condition below that.

[0306] (C3) Timing of the increase in the moving speed of terminal device 40

[0307] (C4) Timing of the terminal device 40 starting to move

[0308] Here, the communication quality indicated in (C2) can be the Reference Signal Received Power (RSRP), Received Signal Strength Indicator (RSSI), or Signal-to-Noise Ratio (SINR).

[0309] <Notification of Measurement Results>

[0310] The terminal device 40 notifies the base station 20 of the measurement results. At this time, the terminal device 40 can perform the notification of measurement results periodically or non-periodically.

[0311] (Periodic notification)

[0312] For example, terminal device 40 can transmit measurement results to base station 20 at a predetermined time. In this case, the measurement execution period can be a combination of multiple time periods. Of course, terminal device 40 can also continuously transmit measurement results at regular intervals.

[0313] (Non-periodic implementation method)

[0314] For example, terminal device 40 can implement notification based on event triggering. For example, terminal device 40 can transmit measurement results to base station 20 when it receives a notification request for measurement results from base station 20. Alternatively, terminal device 40 can trigger notification by measuring a pre-provided or predetermined notification, and transmit the measurement results to base station 20 at the time the trigger is activated. In this case, the trigger can be one of the following (D1) to (D9).

[0315] (D1) The communication quality indicator standard (e.g., a predetermined threshold) of the cell to which terminal device 40 belongs, or a timing value exceeding the standard, is...

[0316] (D2) The communication quality indicator standard (e.g., a predetermined threshold) or below of the timing of the cell to which terminal device 40 belongs.

[0317] (D3) The communication quality of the neighboring cell is higher than the communication quality of the cell to which terminal device 40 belongs by an offset or more timing.

[0318] (D4) The timing of a cell whose communication quality becomes higher than that of the cell to which terminal device 40 belongs.

[0319] (D5) The timing when the communication quality of the cell to which terminal device 40 belongs becomes lower than a first standard (e.g., a first threshold) and the communication quality of neighboring cells becomes higher than a second standard (e.g., a second threshold).

[0320] (D6) Timing where the quality of the reference signal resource exceeds a standard (e.g., a predetermined threshold).

[0321] (D7) The quality of the reference signal resource exceeds the reference signal offset or more timing parameters used as the comparison target.

[0322] (D8) The timing of the moving speed indication standard (e.g., a predetermined threshold) or above of the terminal device 40

[0323] (D9) The timing of the moving speed indication standard (e.g., a predetermined threshold) of the terminal device 40 or below.

[0324] Here, the communication quality indicated as (D2) to (D5) can be the Received Reference Signal Power (RSRP), Received Signal Strength Indicator (RSSI), or Signal-to-Noise Ratio (SINR). Furthermore, the reference signal indicated as (D6) to (D7) can be, for example, the Channel State Information Reference Signal (CSI-RS).

[0325] <4-3-3. Formation of Terminal Tracking Cells>

[0326] Base station 20 (e.g., acquisition unit 331 of base station 20) acquires information required for terminal tracking from terminal device 40. Base station 20 (e.g., forming unit 332 of base station 20) forms a terminal tracking cell based on the information received from terminal device 40.

[0327] Subsequently, base station 20 (e.g., tracking unit 333 of base station 20) performs processing to enable point cell tracking of terminal device 40. At this time, base station 20 may transmit information to terminal device 40 for enabling point cell tracking of terminal device 40. For example, in type 1, base station 20 may transmit information to terminal device 40 about the point cell to which terminal device 40 will next connect. In type 2, base station 20 may transmit information to terminal device 40 about the area where the point cell currently belonging to terminal device 40 can track terminal device 40.

[0328] Terminal device 40 (e.g., acquisition unit 431 of terminal device 40) acquires information from base station 20 for enabling point cell tracking of terminal device 40. Subsequently, terminal device 40 (e.g., communication control unit 433 of terminal device 40) connects to point cell based on the information from base station 20.

[0329] <4-4. Details of Type 1>

[0330] As mentioned above, in type 1, for example, such as Figure 16 As shown, base station 20 forms multiple point cells (PCs) covering a predetermined area. For example, in Type 1, base station 20 pre-maps the point cells in a gapless manner. Base station 20 and terminal device 40 switch the point cell PCs to which terminal device 40 is connected to in order to track terminal device 40 moving within that area.

[0331] In Type 1, since the terminal device 40 is attached to an appropriate point cell, frequent point cell handovers may occur as the terminal device 40 moves. Therefore, the terminal device 40 can be pre-connected to multiple point cells.

[0332] For example, terminal device 40 can be configured to connect to two or more point cells in a region. Terminal device 40 can be pre-attached to multiple point cells. For instance, if terminal device 40 has prior knowledge of movement information, it notifies base station 20 of the movement information. Here, the movement information may include at least one of the following: movement route, movement direction, movement speed, and location information of terminal device 40. Based on the movement information received from terminal device 40, base station 20 identifies the point cell that terminal device 40 will connect to in the future.

[0333] Subsequently, base station 20 notifies terminal device 40 of information about the point cell to which terminal device 40 will connect in the future, as information for the point cell to track terminal device 40. The number of point cells that base station 20 notifies terminal device 40 of as the point cell to which terminal device 40 will connect in the future is not limited to one, and can be multiple. For example, base station 20 can not only notify terminal device 40 of the next point cell to connect to, but also the information about the next point cell to connect to. Of course, base station 20 can also notify terminal device 40 of information about the next point cell. Based on the information received from base station 20 (information about the point cell to be connected in the future), terminal device 40 separates from the point cell currently used for communication and pre-establishes a connection to the point cell to be used for communication in the future. Subsequently, depending on movement, terminal device 40 switches the point cell used for communication to one of the multiple pre-connected point cells.

[0334] Here, the information about the point cell to be connected in the future may include at least one of the following (E1) to (E13). Of course, the information about the point cell to be connected in the future may also include information other than the following.

[0335] (E1) Point to Community ID

[0336] (E2) Point cell connection order

[0337] (E3) Information regarding initial access to a point cell

[0338] (E4) PRACH transmission resources of the cell

[0339] (E5) PRACH transmission preamble sequence of the cell

[0340] (E6) Uplink / downlink carrier frequency of the cell

[0341] (E7) Point cell bandwidth

[0342] (E8) A terminal-specific ID (Cell Radio Network Temporary Identifier (C-RNTI)) after a cell handover.

[0343] (E9) Radio resource configuration after cell handover

[0344] (E10) Trigger information used to perform point cell handover

[0345] (E11) Pre-sale information after cell handover

[0346] (E12) Propagation delay information after cell handover

[0347] (E13) Information regarding the two-step initial access

[0348] Type 1 enables communication system 1 to achieve high communication performance. For example, in Type 1, terminal device 40 is pre-connected to the point cell to be connected in the future. Therefore, even when point formation is applied to the radio access network, communication latency caused by point cell handover is suppressed. This allows communication system 1 to achieve high-speed and low-latency communication while realizing large-scale / high-density wireless communication.

[0349] <4-5. Details of Type 2>

[0350] As described above, in Type 2, base station 20 dynamically changes the settings of the point cell PC to track the movement of terminal device 40. Unlike conventional cells, in Type 2, the point cell moves dynamically according to the location of terminal device 40. That is, in Type 2, for example, as... Figure 17As shown, base station 20 requires a dynamic mobile point cell PC to track the movement of terminal device 40.

[0351] Therefore, terminal device 40 can notify base station 20 of its mobility information. Here, the mobility information may include at least one of the following: mobility route, direction of movement, speed of movement, and location information of terminal device 40. Base station 20 can dynamically adjust the cell based on the mobility information received from terminal device 40.

[0352] Meanwhile, there may be situations where the movement of terminal device 40 is not governed by a clear rule, such that terminal device 40 does not move at a certain time during a period of time, but begins to move at another time. In this case, it may be better for terminal device 40 to notify base station 20 of its movement information at an appropriate time than for terminal device 40 to notify base station 20 of its movement information at a predetermined time.

[0353] Therefore, terminal device 40 can notify base station 20 of its mobility information as needed, based on the mobility of the terminal device. At this time, terminal device 40 can provide the mobility information notification by using the uplink resources configured in the configuration authorization. Subsequently, base station 20 can dynamically move the cell based on the mobility information transmitted by terminal device 40.

[0354] Using Type 2, Communication System 1 can also achieve high communication performance. For example, in Type 2, after the initial connection between Terminal Device 40 and Base Station 20, the Point Cell PC moves according to the movement of Terminal Device 40. This eliminates the need for Terminal Device 40 to re-establish the initial connection each time it moves, thereby suppressing communication latency caused by point cell handover. This allows Communication System 1 to achieve both high-speed and low-latency communication while implementing large-scale / high-density wireless communication.

[0355] <4-6. Revert>

[0356] During communication within a terminal tracking cell, terminal device 40 may need to perform a fallback to a wide cell (e.g., a regular cell). For example, when it is unable to control point cell tracking, terminal device 40 needs to perform a fallback to a wide cell. Here, a wide cell is a cell with a wider area than a point cell. A wide cell can be a classic cell or a cell formed through beamforming. A wide cell can also be a cell formed through dot formation functionality. In this case, the terminal tracking cell can be referred to as a small dot cell, and the wide cell can be referred to as a wide dot cell.

[0357] The assumptions that require rollback are (F1) through (F3).

[0358] (F1) The base station 20 is unable to form a terminal tracking cell due to reasons such as lack of information required for terminal tracking.

[0359] (F2) The terminal device 40 has moved to an area where no terminal tracking cell can be provided.

[0360] (F3) Due to the high mobile speed, base station 20 is unable to provide terminal device 40 with information about the terminal tracking cell.

[0361] When a rollback is required, for example, if the point cell (or small point cell) cannot track the terminal device 40, the base station 20 (e.g., the rollback unit 334 of the base station 20) can perform a rollback from the terminal tracking cell to the wide cell (or wide point cell) to which the terminal device 40 is connected.

[0362] <4-7. Signal Processing>

[0363] Next, the signal processing in the case of applying terminal tracking cells to a radio access network will be described.

[0364] <4-7-1. Reference Signal>

[0365] When applying dot-forming technology to a radio access network, it is assumed that the radio access network has a form in which one dot cell (e.g., a terminal tracking cell) is used by only one terminal device 40. In the case where only one dot cell (e.g., a terminal tracking cell) is used by one terminal device 40, it is not necessary to perform multiple-user multiple-input multiple-output (multi-user MIMO) with another terminal device 40, thereby reducing the number of antenna ports.

[0366] For example, in conventional communication, multiple terminals are multiplexed simultaneously, and therefore, with regard to the mapping of reference signals, the reference signals are orthogonally mapped for each terminal device 40 to be orthogonal in frequency and time resources. Figure 18 This is a diagram illustrating an example of a mapping of a conventional reference signal.

[0367] Figure 19 This is a diagram illustrating an example of the mapping of reference signals according to this embodiment. In the case where only one terminal device 40 uses a single point cell (e.g., a terminal tracking cell), there will be no multiplexing with another terminal device 40. Therefore, for example, as... Figure 19 As shown, the reference signal can be mapped onto all subcarriers of a symbol. This results in improved communication quality.

[0368] Of course, the reference signal does not need to be mapped to all subcarriers of a symbol. Figure 20 This is a diagram illustrating another example of the mapping of reference signals according to this embodiment. Figure 20 In the example, the reference signal is sparsely mapped. A portion of a symbol is assigned as a data signal transmission range. This allows for increased data transmission resources.

[0369] <4-7-2. Scheduling>

[0370] When only one terminal device 40 uses a single point cell (e.g., a terminal tracking cell), that terminal device 40 does not need to share communication resources with another terminal device 40. Therefore, the base station 20 can continuously provide communication resources exclusively to that specific terminal device 40.

[0371] Accordingly, base station 20 (e.g., scheduling unit 335 of base station 20) may omit part or all of the conventional scheduling process. For example, base station 20 may perform predetermined scheduling for wide cells (wide point cells) that have a wider area than point cells, and may omit part or all of the scheduling performed on point cells (small point cells) in wide cells.

[0372] For example, when base station 20 performs point formation (or when only one terminal device 40 uses a point cell), base station 20 may omit at least one of the scheduling of communication resources in the frequency direction and the scheduling of communication resources in the time direction. Furthermore, when base station 20 performs point formation (or when only one terminal device 40 uses a point cell), base station 20 may omit cross-carrier scheduling in carrier aggregation or dual connectivity.

[0373] (Communication resources in the frequency direction)

[0374] When only one terminal device 40 uses a single point cell (e.g., a terminal tracking cell), all assigned frequency bands can be continuously used by that specific terminal device 40. This eliminates the need for frequency-direction scheduling. In this case, the terminal device 40 can continuously use the entire frequency band to perform communication.

[0375] (Communication resources in the time direction)

[0376] When only one terminal device 40 uses a single point cell (e.g., a terminal tracking cell), the terminal device 40 can perform communication with virtually no time constraints. However, when the uplink and downlink are out of sync between terminal tracking cells, for example, the uplink signal of the first terminal tracking cell may interfere with the downlink signal of the second terminal tracking cell.

[0377] Therefore, when cross-terminal tracking cells use the same frequency band, base station 20 and / or terminal device 40 can synchronize communication directions such as uplink and downlink across terminal tracking cells to achieve cross-terminal tracking cell synchronization. At this time, base station 20 can notify terminal device 40 of information regarding communication directions such as uplink or downlink. This information can be set via semi-static advance notification or via dynamic notification.

[0378] (Cross-carrier scheduling)

[0379] When only one terminal device 40 uses a single point cell (e.g., a terminal tracking cell), cross-carrier scheduling will not be required in carrier aggregation or dual connectivity. When the assigned communication frequency band is a terminal-specific communication resource, the terminal device 40 can perform communication without cross-carrier scheduling.

[0380] <<5. Methods for Initial Connection to Terminal Tracking Cell>>

[0381] The operation of the communication system for terminal tracking cells has been described above. Next, the initial connection means in a point-based radio access network will be described.

[0382] <5-1. Overview of methods for determining cell locations>

[0383] First, an overview of the methods for determining cell locations will be provided.

[0384] Upon initial connection to a terminal tracking cell (hereinafter referred to as a point cell), base station 20 and / or terminal device 40 perform processing to determine the point cell to which terminal device 40 belongs. The means of determining the point cell may be one of the following (M1) to (M3). Of course, the means of determining the point cell may be other than (M1) to (M3).

[0385] (M1) Point cell determination method based on synchronization signal

[0386] (M2) Location-based cell determination methods

[0387] (M3) Point cell determination method based on anchor cell

[0388] Terminal device 40 performs initial access based on any of (M1) to (M3) described above. The base station 20 and / or terminal device 40 use which of the above means (M1) to (M3) to determine which cell can be determined by the administrator of communication system 1 (such as a network operator).

[0389] The following section will describe the outline of (M1) to (M3) above.

[0390] (M1) Point cell determination method based on synchronization signal

[0391] For example, the cell to which the terminal device 40 belongs can be determined based on the synchronization signal transmitted by the base station 20. The cell determination method based on the synchronization signal can be any of type A or type B. Of course, the cell determination method based on the synchronization signal can be a method other than type A or type B.

[0392] (1) Type A

[0393] Figure 21 This diagram illustrates an example of a point cell determination method based on synchronization signals. Base station 20 forms multiple point cells (PCs) covering a predetermined area. Base station 20 performs processing to determine the point cell PC to which terminal device 40 belongs. For example, base station 20 transmits multiple synchronization signals to terminal device 40 for terminal device 40 to identify the point cell PC. Subsequently, terminal device 40 determines the point cell PC to connect to based on the received synchronization signals. For example, terminal device 40 pre-stores information for associating predetermined information about the synchronization signals (e.g., at least one of sequence, frequency resources, and time resources) with the point cell ID. Subsequently, terminal device 40 specifies the point cell PC to connect to based on the pre-stored information and the received synchronization signals. After specifying the point cell PC, terminal device 40 connects to the specified point cell PC.

[0394] (2) Type B

[0395] Figure 22 This diagram illustrates another example of a point cell determination method based on synchronization signals. Base station 20 can form a wide cell (WC), which is a cell with a wider area than a point cell (PC). When a wide cell (WC) is formed by a point formation function, it can also be called a wide-point cell. In this case, the point cell (PC) can also be called a small-point cell. A wide cell (WC) is not limited to a cell formed by a point formation function. For example, a wide cell (WC) can be a conventional communication cell (classic cell) or a cell formed by a beamforming function. These cell terms are not limited to wide cell / wide-point cell or point cell / small-point cell.

[0396] Base station 20 forms one or more wide cells (WCs) covering a predetermined area and multiple point cells (PCs) covering the wide cells (WCs). Terminal device 40 selects a wide cell (WC) to connect to. Then, terminal device 40 connects to (e.g., attaches to) base station 20. After terminal device 40 connects to the wide cell (WC), base station 20 transmits multiple synchronization signals to terminal device 40 to allow terminal device 40 to identify the point cells (PCs) included in the wide cell (WC) to which terminal device 40 belongs. Then, terminal device 40 determines the point cell (PC) to connect to based on the received synchronization signals. For example, terminal device 40 pre-stores information for associating predetermined information about the synchronization signals (e.g., at least one of sequence, frequency resources, and time resources) with the point cell ID. Then, terminal device 40 specifies the point cell (PC) to connect to based on the pre-stored information and the received synchronization signals. After specifying the point cell (PC), terminal device 40 connects to the specified point cell (PC).

[0397] (M2) Location-based cell determination methods

[0398] Base station 20 can form a cell different from the point cell PC. For example, base station 20 can form a wide cell (WC), which is a cell with a wider area than the point cell PC. Terminal device 40 selects the cell to connect to (e.g., wide cell WC). Subsequently, terminal device 40 connects to base station 20. During or after the connection, base station 20 acquires the location information of terminal device 40. At this time, base station 20 can acquire the location information from terminal device 40. In addition, base station 20 can measure the location of terminal device 40 and acquire this measurement information as the location information of terminal device 40. Subsequently, based on the location information of terminal device 40, base station 20 determines the point cell to which terminal device 40 belongs.

[0399] Using this method (a cell determination method based on location information), base station 20 can determine an appropriate cell based on the location information of terminal device 40. Therefore, it is not necessary to perform the association between synchronization signal and cell as described in the cell determination method based on synchronization signal described above.

[0400] (M3) Point cell determination method based on anchor cell

[0401] When establishing a connection with a point cell, terminal device 40 can connect to a conventional base station (another base station) that does not perform point formation. For example, if a cell exists that serves as an anchor for point formation by a conventional base station, terminal device 40 can connect to the cell used as the anchor. After the connection is established, base station 20 and / or terminal device 40 can determine the point cell to which terminal device 40 belongs based on information from the other base station 20. For example, terminal device 40 can determine the point cell to which it belongs through communication within the cell used as the anchor.

[0402] <5-2. Details of the methods for determining the location of a residential area>

[0403] The above has provided an overview of the point cell determination methods. The following sections will describe these methods in detail.

[0404] <5-2-1. Point Cell Determination Method Based on Synchronization Signals>

[0405] First, the method for determining point cells based on synchronization signals will be described in detail.

[0406] For example, the cell to which the terminal device 40 belongs can be determined based on the synchronization signal transmitted by the base station 20. For example, the cell to which the terminal device 40 belongs can be determined based on the power of the synchronization signal transmitted by the base station 20. As described above, the cell determination method based on the synchronization signal can be of type A or type B. Type A and type B will be described in detail below.

[0407] (1) Type A

[0408] Base station 20 pre-forms multiple point cells (e.g., for point formation support areas) covering the entire area of ​​a predetermined region. Figure 21 (The point cell shown is PC). Subsequently, base station 20 transmits multiple synchronization signals to terminal device 40 for terminal device 40 to identify the point cell. Then, terminal device 40 determines the point cell to attach to based on the received synchronization signals.

[0409] In this embodiment example, base station 20 pre-forms point cells throughout the entire interval of a predetermined area. Terminal device 40 receives the synchronization signal of the point cell to which terminal device 40 belongs. Subsequently, using the resources corresponding to the synchronization signal, terminal device 40 transmits message 1 of the initial access procedure (random access procedure).

[0410] After receiving the message, the base station 20 can determine the cell to which the terminal device 40 belongs based on which cell has received the initial access procedure (random access procedure) message 1.

[0411] Base station 20 can transmit multiple synchronization signals simultaneously. For example, regarding the transmission of synchronization signals for multiple point cells covering a predetermined area, base station 20 can transmit multiple synchronization signals simultaneously. When synchronization signals are transmitted simultaneously, the transmission power is distributed according to the number of point cells, which may lead to a degradation in the reception quality of the point cells. However, the simultaneous transmission of synchronization signals maximizes spatial multiplexing efficiency.

[0412] Base station 20 can transmit multiple synchronization signals in a distributed manner at different times. When synchronization signals are transmitted in a distributed manner at different times, there are periods during which communication cannot be performed in each point cell. Compared to the case where synchronization signals are transmitted simultaneously, this leads to the possibility of degraded spatial multiplexing efficiency. However, because the synchronization signals are transmitted in a distributed manner at different times, the reception quality in the point cell is improved.

[0413] (2) Type B

[0414] Base station 20 pre-forms one or more wide-spot cells covering a predetermined area (e.g., Figure 22 The base station 20 and / or the terminal device 40 select the wide cell to attach to (as shown in the example wide cell WC), and the terminal device 40 selects the wide cell to attach to. After attaching to the wide cell, the base station 20 and / or the terminal device 40 selects the small cell (e.g., a small cell belonging to the selected wide cell) to attach to the wide cell. Figure 22 The appropriate small cell selection process is performed in the point cell (PC) shown in the figure.

[0415] In the following description, wide cell (e.g., Figure 22 The wide cell (WC) shown in the diagram is called a wide point cell, while the point cell (e.g., Figure 22 The dot cell (PC) shown in the diagram is referred to as a small dot cell. The wide dot cell described below can be renamed a wide cell, and the small dot cell can be renamed a dot cell.

[0416] Base station 20 pre-forms one or more wide cells in a predetermined area (e.g., a point formation support area). Then, base station 20 transmits multiple synchronization signals to terminal device 40 for terminal device 40 to identify the wide cells. Terminal device 40 receives the synchronization signal of the wide cell to which terminal device 40 belongs. Subsequently, using the resources corresponding to the synchronization signals, terminal device 40 transmits message 1 of the initial access procedure (random access procedure).

[0417] After receiving the message, the base station 20 can determine the wide cell to which the terminal device 40 belongs based on which wide cell has received the initial access procedure (random access procedure) message 1.

[0418] Base station 20 can transmit multiple synchronization signals simultaneously. For example, regarding the transmission of synchronization signals for multiple wide cells covering a predetermined area, base station 20 can transmit multiple synchronization signals simultaneously. When synchronization signals are transmitted simultaneously, the transmission power is distributed according to the number of wide cells, which may lead to a degradation in the reception quality of the wide cells. However, the simultaneous transmission of synchronization signals maximizes spatial multiplexing efficiency.

[0419] Base station 20 can transmit multiple synchronization signals in a distributed manner at different times. When synchronization signals are transmitted in a distributed manner at different times, there are periods during which communication cannot be performed in each point cell. Compared to the case of simultaneous transmission of synchronization signals, this may lead to a degradation in spatial multiplexing efficiency. However, when synchronization signals are transmitted in a distributed manner at different times, the reception quality of the point cells is improved.

[0420] After initial access is performed, base station 20 and terminal device 40 communicate in the wide-spot cell to which terminal device 40 belongs.

[0421] After terminal device 40 connects to a wide-spot cell, base station 20 can transmit multiple synchronization signals to terminal device 40 to allow terminal device 40 to identify small-spot cells included in the wide-spot cell to which terminal device 40 belongs. Subsequently, terminal device 40 can determine the small-spot cell to connect to based on the received synchronization signals. After terminal device 40 begins communication in the wide-spot cell, base station 20 can perform processing to change the cell to which terminal device 40 is connected from the wide-spot cell to a small-spot cell. For example, base station 20 can transmit multiple different reference signals associated with multiple small-spot cells to terminal device 40. For example, terminal device 40 can measure the reception quality of the received reference signals and provide the result as feedback to base station 20. Based on the feedback information from terminal device 40, base station 20, having received the feedback, can determine the small-spot cell to which terminal device 40 belongs.

[0422] Subsequently, terminal device 40 can perform random access with the small cell determined by base station 20. At this stage, terminal device 40 has completed the connection with the wide cell. Accordingly, base station 20 can only transmit synchronization signals from the small cells belonging to the area of ​​that wide cell. At this time, the synchronization signal of the small cell and the small cell ID can be associated with each other. Then, terminal device 40 can identify the small cell ID to connect to based on the synchronization signal.

[0423] Base station 20 and terminal device 40 can be configured to combine multiple frequency bands through carrier aggregation or dual connectivity. Base station 20 and terminal device 40 can use at least one of the multiple frequency bands as the frequency band for providing a point cell to perform communication.

[0424] For example, base station 20 and terminal device 40 can combine wide-spot cells and small-spot cells with mechanisms such as carrier aggregation or dual connectivity. For example, base station 20 and terminal device 40 can use at least one of a plurality of frequency bands as the frequency band providing wide-spot cells and use at least another frequency band as the frequency band providing small-spot cells to perform communication.

[0425] For example, base station 20 and terminal device 40 can set frequency band A used in carrier aggregation to provide wide-spot cells and frequency band B used in carrier aggregation to provide small-spot cells. Furthermore, base station 20 and terminal device 40 can set frequency band A used in dual connectivity to provide wide-spot cells and frequency band B used in dual connectivity to provide small-spot cells. Additionally, terminal device 40 can set base station A used in dual connectivity to provide wide-spot cells and base station B used in dual connectivity to provide small-spot cells.

[0426] <5-2-2. Location-Based Cell Determination Methods>

[0427] Next, we will describe in detail the methods for determining point cells based on location information.

[0428] Base station 20 pre-forms one or more cells covering a predetermined area. At this time, the cells formed by base station 20 can be different from point cells (small point cells). For example, the cells formed by base station 20 can be wide cells. Subsequently, terminal device 40 selects a cell to attach to and attaches to that cell. During or after attachment, base station 20 acquires the location information of terminal device 40. At this time, base station 20 can acquire location information from terminal device 40. Furthermore, base station 20 can measure the location of terminal device 40 and acquire the measurement information as the location information of terminal device 40. Subsequently, based on the location information of terminal device 40, base station 20 determines the point cell to which terminal device 40 belongs.

[0429] Base station 20 pre-forms one or more cells (e.g., wide cells) in a predetermined area (e.g., a point formation support area). Then, base station 20 transmits multiple synchronization signals to terminal device 40 for cell identification. Terminal device 40 receives the synchronization signal of the cell to which it belongs. Subsequently, using the resources corresponding to the synchronization signals, terminal device 40 transmits message 1 of the initial access procedure (random access procedure).

[0430] After receiving the message, the base station 20 can determine the cell to which the terminal device 40 belongs based on which cell received the initial access procedure (random access procedure) message 1.

[0431] During or after the initial access process, the base station 20 acquires the location information of the terminal device 40.

[0432] At this time, base station 20 can obtain location information from terminal device 40. For example, terminal device 40 can measure its location based on information such as a location measuring device included in terminal device 40. Terminal device 40 can notify base station 20 of the measured location. Base station 20 can obtain the information provided by terminal device 40 as the location information of terminal device 40.

[0433] Furthermore, base station 20 can measure the position of terminal device 40. Subsequently, base station 20 can acquire the measurement information as the position information of terminal device 40. At this time, base station 20 can transmit a reference signal (e.g., a positioning reference signal) for position measurement to terminal device 40, and terminal device 40 can transmit the measurement result as feedback to base station 20.

[0434] Note that base station 20 can use the area ID used in vehicle-to-X (V2X) and the like to obtain the location information of terminal device 40.

[0435] Subsequently, base station 20 can determine the point cell (small point cell) to which terminal device 40 belongs based on the location information of terminal device 40. Base station 20 can then notify terminal device 40 of the information required for communication within that point cell.

[0436] Subsequently, terminal device 40 performs communication within the point cell to which terminal device 40 belongs.

[0437] <5-2-3. Point Cell Determination Methods Based on Anchor Cells>

[0438] Next, we will describe in detail the point cell determination method based on anchor cells.

[0439] When establishing a connection with a point cell, terminal device 40 can attach to a cell that serves as an anchor, formed by a conventional base station (another base station) that does not perform point formation. After attachment, base station 20 and / or terminal device 40 can determine the point cell to which terminal device 40 belongs based on information from that other base station 20.

[0440] In this embodiment example, terminal device 40 receives a synchronization signal from an anchor cell formed by a conventional base station. Subsequently, using the resources corresponding to the synchronization signal, terminal device 40 transmits message 1 of the initial access procedure (random access procedure).

[0441] After receiving the message, the base station 20 can determine the anchor cell to which the terminal device 40 belongs based on which cell received the initial access procedure (random access procedure) message 1.

[0442] After initial access is performed, base station 20 and terminal device 40 communicate in the anchor cell.

[0443] After communication is initiated, base station 20 may perform a process for adding a point cell (small point cell) (hereinafter referred to as point cell addition process). The point cell addition process may be one of the following (G1) to (G3).

[0444] (G1) Point cell addition processing via power measurement

[0445] For example, base station 20 can notify terminal device 40 of the information required to communicate with point cell through communication in anchor cell.

[0446] Furthermore, base station 20 can transmit multiple different reference signals associated with a point cell to terminal device 40. At this time, terminal device 40 can measure the reception quality of the received reference signals and provide the result as feedback to base station 20. Based on the feedback information from terminal device 40, base station 20, upon receiving the feedback, can determine the point cell to which terminal device 40 belongs. Subsequently, terminal device 40 can begin communication with the determined point cell.

[0447] In addition, the terminal device 40 can use the random access information about the point cell to perform random access with the point cell.

[0448] (G2) Location-based cell addition processing

[0449] During or after the initial access process, base station 20 may acquire the location information of terminal device 40.

[0450] At this time, base station 20 can obtain location information from terminal device 40. For example, terminal device 40 can measure its location based on information such as a location measuring device included in terminal device 40. Terminal device 40 can notify base station 20 of the measured location. Base station 20 can obtain the information provided by terminal device 40 as the location information of terminal device 40.

[0451] Furthermore, base station 20 can measure the position of terminal device 40. Subsequently, base station 20 can acquire the measurement information as the position information of terminal device 40. At this time, base station 20 can transmit a reference signal (e.g., a positioning reference signal) for position measurement to terminal device 40, and terminal device 40 can transmit the measurement result as feedback to base station 20.

[0452] Subsequently, base station 20 can determine the point cell (small point cell) to which terminal device 40 belongs based on the location information of terminal device 40. Base station 20 can then notify terminal device 40 of the information required for communication in that point cell through communication within the anchor cell.

[0453] Subsequently, terminal device 40 performs communication within the point cell to which terminal device 40 belongs.

[0454] (G3) Point cell addition processing based on information from another base station

[0455] Base station 20 can obtain information about terminal device 40 from a conventional base station (another base station) that provides the anchor cell to terminal device 40. Subsequently, base station 20 can determine the point cell to which terminal device 40 belongs based on the information from the conventional base station (another base station).

[0456] Furthermore, the conventional base station (another base station) providing the anchor cell to the terminal device 40 can be configured to determine the point cell to which the terminal device 40 belongs. Base station 20 can obtain the determination information of the point cell to which the terminal device 40 belongs from the conventional base station (another base station). Subsequently, base station 20 can determine the point cell to which the terminal device 40 belongs based on the determination information obtained from the conventional base station (another base station).

[0457] <5-2-4. Supplementary Explanation>

[0458] The synchronization signal transmitted from base station 20 can be one of the following (H1) to (H3).

[0459] (H1) Master Synchronization Signal (PSS)

[0460] (H2) Auxiliary Synchronization Signal (SSS)

[0461] (H3) Third Synchronization Signal (TSS)

[0462] System information transmitted from base station 20 can be transmitted through one of the following (I1) to (I2).

[0463] (I1) PBCH (Physical Broadcast Channel)

[0464] (I2) PDSCH (Physical Downlink Shared Channel)

[0465] As the information required to determine the cell, at least one of the following pieces of information (J1) to (J3) can be provided in the notification from the terminal device 40 to the base station 20.

[0466] (J1) Location measurement capability information

[0467] (J2) Location information of the terminal device

[0468] (J3) Channel Information

[0469] For example, terminal device 40 receives a reference signal transmitted from base station 20 and measures the channel matrix between each antenna element and terminal device 40. Subsequently, terminal device 40 notifies base station 20 of the measurement results as channel information. Terminal device 40 may also notify base station 20 of unprocessed measurement results as channel information. Alternatively, terminal device 40 may apply eigenvalue decomposition to the channel matrix to obtain an eigenvalue vector and notify base station 20 of this eigenvalue vector as channel information.

[0470] <<6. Revision>>

[0471] The above embodiments are examples, and various modifications and applications are possible.

[0472] <6-1. Functional Separation>

[0473] The functionality of the base station 20 in this embodiment can be divided into multiple functions, such as a central unit (CU), a distributed unit (DU), and a radio unit (RU). Here, the DU may include some or all of the functions known by names such as Radio Remote Header (RRH), Remote Radio Unit (RRU), and Radio Unit (RU) as named in 3GPP LTE.

[0474] For example, when base station 20 is established, a configuration is permitted whereby the entity performing central control (e.g., CU or DU) handles the Media Access Control (MAC) layer or higher, while the transmission antenna group used as a transmission point handles the Physical (PHY) layer or lower. For instance, the central control entity could handle the Serving Data Adaptation Protocol (SDAP) / Packet Data Convergence Protocol (PDCP) / Radio Link Control (RLC) / MAC layer, and the PHY / RF layer at each transmission point.

[0475] This enables efficient point formation processing.

[0476] <6-2. Point Formation>

[0477] The above embodiments have described wireless communication using a technique (power concentration technique) that concentrates power at a specific point by utilizing near-field phase differences. However, the point-forming wireless communication according to this embodiment can also be near-field communication. Here, near-field communication can be communication over a distance shorter than the Fraunhofer distance, which is determined by the frequency band and the opening length of the transmission panel.

[0478] Furthermore, the above embodiments have described an example of one base station 20 performing point formation-related processing. However, multiple base stations 20 can collaboratively perform point formation-related processing. For example, multiple base stations 20 can form a point cell by collaboratively controlling each transmit antenna with another base station 20. Base station 20 can perform collaborative control with relay station 30.

[0479] <6-3. Other Modifications>

[0480] In the above embodiments, the technology of this disclosure has been described using communication processing between base station 20 and terminal device 40 as an example. However, the application scope of this embodiment is not limited thereto. For example, the technology of this disclosure is also applicable to communication between multiple communication devices selected from management device 10, base station 20, relay station 30, and terminal device 40. Furthermore, the technology of this disclosure is also applicable to communication between management devices 10, between base stations 20, between relay stations 30, or between terminal devices 40.

[0481] The control device that controls the management device 10, base station 20, relay station 30 and terminal device 40 in this embodiment can be implemented by a dedicated computer system or a general-purpose computer system.

[0482] For example, the communication program used to perform the above operations is stored in and distributed on a computer-readable recording medium (such as an optical disc, semiconductor memory, magnetic tape, or floppy disk). For example, the program is installed on a computer and the above processing is performed to configure the control device. In this case, the control device may be an external device (e.g., a personal computer) of the management device 10, base station 20, relay station 30, or terminal device 40. Alternatively, the control device may be an internal device (e.g., control unit 13, control unit 23, control unit 33, or control unit 43) of the management device 10, base station 20, relay station 30, or terminal device 40.

[0483] Furthermore, for example, the aforementioned communication program can be stored on a disk device included in a server on a network such as the Internet, so that it can be downloaded to a computer. Additionally, the aforementioned functionality can be achieved through the collaborative use of an operating system (OS) and application software. In this case, for example, parts other than the OS can be stored on a medium for distribution, or parts other than the OS can be stored on a server for download to a computer.

[0484] Furthermore, in the various processes described in the above embodiments, all or part of the processes described as automatically executed can be performed manually, or processes described as manually executed can be automatically executed by known methods. Moreover, unless otherwise specified, the processing procedures, specific names, and information including various data and parameters shown in the above documents or figures can be flexibly changed. For example, the various types of information shown in each figure are not limited to the information shown.

[0485] Furthermore, each component of each device is provided as a functional and conceptual illustration, and therefore does not necessarily require the physical configuration shown in the figures. That is, the specific form of distribution / integration of each device is not limited to the form shown in the figures, and all or part of it can be functionally or physically distributed or integrated to form arbitrarily determined units according to various loads and usage conditions. Such configuration through distribution or integration can be implemented dynamically.

[0486] Furthermore, the above embodiments can be appropriately combined within feasible limits without causing processing conflicts. Additionally, the order of the various steps shown in the flowcharts or sequence diagrams of the above embodiments can be appropriately modified.

[0487] Furthermore, this embodiment can be implemented as any configuration constituting a device or system, such as a processor such as a large-scale integrated circuit (LSI), a module using multiple processors, a unit using multiple modules, and a collection obtained by further adding other functions to the unit (i.e., a configuration of a part of a device).

[0488] In this embodiment, a system refers to a collection of multiple components (devices, modules (parts), etc.), and whether all components are located in the same housing is not a major issue. Therefore, multiple devices housed in separate housings and connected via a network, as well as a single device in which multiple modules are housed in one housing, are both systems.

[0489] Furthermore, for example, this embodiment may employ a cloud computing component, in which one function is shared and processed collaboratively by multiple devices or equipment via a network.

[0490] <<7. Conclusion>>

[0491] Base station 20 forms a point cell using power concentration technology (point formation). For example, base station 20 performs coordinated control of multiple antennas to concentrate power at a specific point, thereby forming a point cell. Base station 20 then performs processing to enable the point cell to track terminal device 40. For example, base station 20 acquires information about terminal device 40. Subsequently, base station 20 performs processing based on the information about terminal device 40 to enable the point cell to track terminal device 40.

[0492] In this manner, in this embodiment, base station 20 performs processing to enable point cell tracking of terminal device 40. Therefore, even when terminal device 40 moves, it can maintain uninterrupted connection to the point cell. This enables high communication performance. For example, communication system 1 can achieve high-speed and low-latency communication while implementing large-scale / high-density wireless communication.

[0493] Embodiments of the present invention have been described above. However, the scope of this disclosure is not limited to the above embodiments, and various modifications can be made without departing from the scope of this disclosure. Moreover, it is permissible to appropriately combine components across different embodiments and modifications.

[0494] The effects described in the various embodiments of this specification are merely examples, and other effects may exist, and are not limited to those illustrated.

[0495] Note that this technology can also have the following configurations. (1)

[0497] A base station, comprising:

[0498] Forming units, the forming units being configured to form point cells by concentrating power at a specific point through the coordinated control of multiple antennas; and

[0499] A tracking unit configured to perform processing for enabling a point cell tracking terminal device. (2)

[0501] According to the base station described in (1), it also includes

[0502] The acquisition unit is configured to acquire information about the terminal device.

[0503] The tracking unit performs processing to enable cell tracking of the terminal device based on the information about the terminal device. (3)

[0505] According to the base station described in (2),

[0506] The acquisition unit acquires at least one of the following: information about the moving direction of the terminal device, information about the moving speed of the terminal device, and information about the location of the terminal device, as the information about the terminal device. (4)

[0508] According to the base station described in (2) or (3),

[0509] The acquisition unit acquires information about the interference power received by the terminal device, which is then used as the information about the terminal device. (5)

[0511] According to any one of (2) to (4) the base station,

[0512] The acquisition unit acquires information about the near field or far field, which is then used as information about the terminal device. (6)

[0514] According to any one of (2) to (5) the base station,

[0515] The acquisition unit acquires information about the mobile schedule of the terminal device, which is used as the information about the terminal device. (7)

[0517] According to any one of (1) to (6) the base station,

[0518] The forming unit forms multiple point cells within a predetermined area, and

[0519] The tracking unit performs a process of switching the point cell to which the terminal device is connected, so that the point cell tracks the terminal device moving within the predetermined area. (8)

[0521] According to the base station described in (7),

[0522] The terminal device is configured to connect to two or more of the plurality of point cells, and

[0523] The tracking unit notifies the terminal device of information about the point cell that the terminal device will connect to in the future. (9)

[0525] According to the base station described in (8),

[0526] The tracking unit provides notifications about the connection order of point cells as information about the point cells that the terminal device will connect to in the future. (10)

[0528] According to the base station described in (8) or (9),

[0529] The tracking unit provides notifications about the initial two-step access as information about the point cell the terminal device will connect to in the future. (11)

[0531] According to the base station described in (1),

[0532] The tracking unit dynamically moves the cell to track the movement of the terminal device. (12)

[0534] According to the base station described in (11),

[0535] The tracking unit is based on the mobile information transmitted by the terminal device to dynamically move the cell. (13)

[0537] The base station according to any one of (1) to (12) also includes

[0538] A fallback unit is configured to perform a fallback such that when a point cell cannot track a terminal device, the cell to which the terminal device is connected undergoes a fallback to a wide cell, which has a wider area than a point cell. (14)

[0540] The base station according to any one of (1) to (13) also includes

[0541] A scheduling unit, configured to perform scheduling for sharing cell resources among multiple terminal devices.

[0542] The scheduling unit performs scheduling for wide cells that have a wider area than point cells and omits some or all of the scheduling for point cells. (15)

[0544] A terminal device capable of connecting to a base station, the base station being able to form a point cell by concentrating power at a specific point through the coordinated control of multiple antennas, the terminal device comprising:

[0545] An acquisition unit, configured to acquire information from a base station for enabling a point cell tracking terminal device; and

[0546] A communication control unit configured to connect to a point cell based on information for enabling the point cell tracking terminal device to do so. (16)

[0548] According to the terminal device described in (15),

[0549] Multiple point cells are formed within the designated area.

[0550] The acquisition unit acquires information about the point cell that the terminal device will connect to in the future, as information used by the point cell to track the terminal device.

[0551] The communication control unit switches the point cell that the terminal device will use based on information about the point cell that the terminal device will connect to in the future. (17)

[0553] The terminal device according to (15) also includes

[0554] A transmission unit configured to transmit mobile information of a terminal device to a base station, the base station dynamically moving a cell to track the movement of the terminal device. (18)

[0556] A communication method, comprising:

[0557] Point cells are formed by concentrating power at a specific point through the coordinated control of multiple antennas; and

[0558] Perform the processing for the point cell tracking terminal device. (19)

[0560] A communication method executed by a terminal device capable of connecting to a base station, the base station being able to form a point cell by concentrating power at a specific point through the coordinated control of multiple antennas, the communication method comprising:

[0561] Obtain information from the base station for enabling the point cell tracking terminal device; and

[0562] This is based on the information used to connect the point cell tracking terminal device to the point cell. (20)

[0564] A communication system includes: a base station; and a terminal device.

[0565] The base stations include:

[0566] Forming units, the forming units being configured to form point cells by concentrating power at a specific point through the coordinated control of multiple antennas; and

[0567] The tracking unit is configured to perform processing for enabling the point cell tracking terminal device, and

[0568] The communication system also includes:

[0569] An acquisition unit, configured to acquire information from a base station for enabling a point cell tracking terminal device; and

[0570] A communication control unit configured to connect to a point cell based on information for enabling the point cell tracking terminal device to do so.

[0571] List of reference numerals

[0572] 1. Communication System

[0573] 10 Management Device

[0574] 20 base stations

[0575] 30 relay stations

[0576] 40 Terminal devices

[0577] 11 Communication Unit

[0578] 21, 31, 41 Wireless communication units

[0579] 12, 22, 32, 42 storage units

[0580] Control units 13, 23, 33, 43

[0581] 211, 311, 411 Transmission Processing Units

[0582] 212, 312, 412 Receiving and Processing Units

[0583] 213, 313, 413 antennas

[0584] Acquisition Units 231, 331, and 431

[0585] 232, 332 forming units

[0586] 233, 333 tracking units

[0587] 234, 334 rollback unit

[0588] 235, 335 scheduling units

[0589] 432 Transmission Unit

[0590] 433 Communication Control Unit

[0591] RAN (Radio Access Network)

[0592] CN Core Network

Claims

1. A base station, comprising: Forming unit, the forming unit being configured to form a point cell by concentrating power at a specific point through the coordinated control of multiple antennas; as well as A tracking unit configured to perform processing for enabling a point cell tracking terminal device.

2. The base station according to claim 1, further comprising: The acquisition unit is configured to acquire information about the terminal device. The tracking unit performs processing to enable cell tracking of the terminal device based on the information about the terminal device.

3. The base station according to claim 2, The acquisition unit acquires at least one of the following: information about the moving direction of the terminal device, information about the moving speed of the terminal device, and information about the location of the terminal device, as the information about the terminal device.

4. The base station according to claim 2, The acquisition unit acquires information about the interference power received by the terminal device, which is then used as the information about the terminal device.

5. The base station according to claim 2, The acquisition unit acquires information about the near field or far field, which is then used as information about the terminal device.

6. The base station according to claim 2, The acquisition unit acquires information about the mobile schedule of the terminal device, which is used as the information about the terminal device.

7. The base station according to claim 1, The forming unit forms multiple point cells within a predetermined area, and The tracking unit performs a process of switching the point cell to which the terminal device is connected, so that the point cell tracks the terminal device moving within the predetermined area.

8. The base station according to claim 7, The terminal device is configured to connect to two or more of the plurality of point cells, and The tracking unit notifies the terminal device of information about the point cell that the terminal device will connect to in the future.

9. The base station according to claim 8, The tracking unit provides notifications about the connection order of point cells as information about the point cells that the terminal device will connect to in the future.

10. The base station according to claim 8, The tracking unit provides notifications about the initial two-step access as information about the point cell the terminal device will connect to in the future.

11. The base station according to claim 1, The tracking unit dynamically moves the cell to track the movement of the terminal device.

12. The base station according to claim 11, The tracking unit is based on the mobile information transmitted by the terminal device to dynamically move the cell.

13. The base station according to claim 1, further comprising: A fallback unit is configured to perform a fallback such that when a point cell cannot track a terminal device, the cell to which the terminal device is connected undergoes a fallback to a wide cell, which has a wider area than a point cell.

14. The base station according to claim 1, further comprising: A scheduling unit, configured to perform scheduling for sharing cell resources among multiple terminal devices. The scheduling unit performs scheduling for wide cells that have a wider area than point cells and omits some or all of the scheduling for point cells.

15. A terminal device capable of connecting to a base station, the base station being able to form a point cell by concentrating power at a specific point through coordinated control of multiple antennas in a point cell to which the terminal device is connected, the terminal device comprising: The acquisition unit is configured to acquire information from the base station for enabling the point cell tracking terminal device; as well as A communication control unit configured to connect to a point cell based on information for enabling the point cell tracking terminal device to do so.

16. The terminal device according to claim 15, Multiple point cells are formed within the designated area. The acquisition unit acquires information about the point cell that the terminal device will connect to in the future, as information used by the point cell to track the terminal device. The communication control unit switches the point cell that the terminal device will use based on information about the point cell that the terminal device will connect to in the future.

17. The terminal device according to claim 15, further comprising: A transmission unit configured to transmit mobile information of a terminal device to a base station, the base station dynamically moving a cell to track the movement of the terminal device.

18. A communication method, comprising: Point cells are formed by concentrating power at a specific point through the coordinated control of multiple antennas. as well as Perform the processing for the point cell tracking terminal device.

19. A communication method performed by a terminal device capable of connecting to a base station, the base station being able to form a point cell by concentrating power at a specific point through the coordinated control of multiple antennas, the communication method comprising: Obtain information from the base station to enable the cell tracking terminal device; as well as This is based on the information used to connect the point cell tracking terminal device to the point cell.

20. A communication system, comprising: Base station; and terminal devices, The base stations include: Forming units, the forming units being configured to form point cells by concentrating power at a specific point through the coordinated control of multiple antennas; and The tracking unit is configured to perform processing for enabling the point cell tracking terminal device, and The communication system also includes: An acquisition unit, configured to acquire information from a base station for enabling a point cell tracking terminal device; and A communication control unit configured to connect to a point cell based on information for enabling the point cell tracking terminal device to do so.

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