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

Abstract

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

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a base station, a terminal device, a communication method, and a communication system. BACKGROUND

[0002] Techniques related to wireless communication have been actively developed. Next-generation wireless communication is expected to achieve further improvement in communication performance (e.g., improvement in frequency utilization efficiency). As one of the techniques for improving frequency utilization efficiency, a technique of concentrating power at a specific place using a phase difference of near field is disclosed (e.g., Non-Patent Literature 1).

[0003] List of Citations

[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

[0006] Technical Problem

[0007] The above-described technique (a technique of performing concentration of power at a specific place) is expected to achieve more advanced spatial multiplexing. However, simply applying this technique to a radio access network will not necessarily be able to achieve wireless communication with high communication performance (e.g., higher frequency utilization efficiency, greater capacity, higher speed, lower latency, higher reliability, large-scale / high density, lower power consumption, or lower processing load).

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

[0009] Note that the above-described problem or object is only one of a plurality of problems or objects that can be solved or achieved by a plurality of embodiments disclosed in this specification.

[0010] Solution to Problem

[0011] To solve the above-described problem, a base station according to an embodiment of the present disclosure includes a formation unit configured to form a point cell by concentrating power at a specific place using cooperative control of a plurality of antennas, and a determination processing unit configured to perform processing for determining a point cell to which a terminal device belongs. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a diagram for illustrating a power concentration technique (point shaping).

[0013] Figure 2 is a diagram for illustrating a near field and a far field.

[0014] Figure 3 is a diagram illustrating a Fraunhofer distance defining a boundary between a near field and a far field.

[0015] Figure 4 is a diagram illustrating an example of point shaping using a distributed antenna.

[0016] Figure 5 is a diagram illustrating an outline of the solution in the present embodiment.

[0017] Figure 6 is a diagram illustrating a configuration of a communication system according to the present embodiment.

[0018] Figure 7 is a diagram illustrating a configuration of a management device according to the present embodiment.

[0019] Figure 8 is a diagram illustrating a configuration of a base station according to the present embodiment.

[0020] Figure 9 is a diagram illustrating a configuration of a relay station according to the present embodiment.

[0021] Figure 10 is a diagram illustrating a configuration of a terminal device according to the present embodiment.

[0022] Figure 11 is a flowchart illustrating an example of an initial connection process.

[0023] Figure 12 is a diagram illustrating a contention-based random access procedure.

[0024] Figure 13 is a diagram illustrating a non-contention-based random access procedure.

[0025] Figure 14 is a diagram illustrating a 2-step random access procedure.

[0026] Figure 15 is a diagram for illustrating an example of a point cell determination means based on power of a synchronization signal.

[0027] Figure 16 is a diagram for illustrating another example of a point cell determination means based on power of a synchronization signal.

[0028] Figure 17 is a diagram illustrating a sequence example of initial access procedure related to means for determining a wide cell and a point cell during 4-step RACH procedure.

[0029] Figure 18 is a diagram illustrating a sequence example of initial access procedure related to means for determining a wide cell and a point cell during 4-step RACH procedure.

[0030] Figure 19 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 2-step RACH procedure.

[0031] Figure 20 is a diagram illustrating a sequence example of initial access procedure related to means for determining a wide cell and a point cell during 2-step RACH procedure.

[0032] Figure 21 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 4-step RACH procedure.

[0033] Figure 22 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 4-step RACH procedure.

[0034] Figure 23 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 4-step RACH procedure.

[0035] Figure 24 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 4-step RACH procedure.

[0036] Figure 25 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 4-step RACH procedure.

[0037] Figure 26 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 2-step RACH procedure.

[0038] Figure 27 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 2-step RACH procedure.

[0039] Figure 28 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell during 2-step RACH procedure.

[0040] Figure 29 is a diagram illustrating a sequence example of initial access procedure related to means for determining a point cell by an anchor cell after 4-step RACH procedure.

[0041] Figure 30 is a sequence diagram illustrating an initial access process related to a means of determining a point cell by an anchor cell after a 2-step RACH process.

[0042] Figure 31 is a diagram for illustrating an example of CU / DU / RU separation of the function of the base station 20.

[0043] Figure 32 is a diagram illustrating a separation example of a process related to point shaping.

[0044] Figure 33 is a diagram illustrating a mapping example of a conventional reference signal.

[0045] Figure 34 is a diagram illustrating an example of mapping of a reference signal according to the present embodiment.

[0046] Figure 35 is a diagram illustrating another example of mapping of a reference signal according to the present embodiment. DETAILED DESCRIPTION

[0047] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In each of the following embodiments, the same parts are denoted by the same reference symbols, and repetitive description thereof will be omitted.

[0048] Further, in the present specification and drawings, a plurality of components having substantially the same functional configuration will be distinguished by appending different letters or numbers to the same reference symbol. For example, a plurality of configurations having substantially the same functional configuration, such as terminal devices 401, 402, and 403, are distinguished as necessary. However, when there is no particular need to distinguish a plurality of components having substantially the same functional configuration, only the same reference symbol is given. For example, in the case where there is no particular need to distinguish the terminal devices 401, 402, and 403, they are simply referred to as terminal devices 40.

[0049] One or more embodiments described below, including implementation examples and modifications, can each be independently implemented. On the other hand, at least some of a plurality of embodiments described below can be appropriately combined with at least some of other embodiments. A plurality of embodiments can include novel features different from each other. Therefore, a plurality of embodiments can contribute to achieving or solving different purposes or problems, and can exhibit different effects.

[0050] The present disclosure will be described in the following order of items.

[0051] 1. SUMMARY

[0052] 1-1. PROBLEMS

[0053] 1-2. Power concentration technique (spot forming)

[0054] 1-3. Summary of the solution

[0055] 2. Configuration of the communication system

[0056] 2-1. Configuration of the management apparatus

[0057] 2-2. Configuration of the base station

[0058] 2-3. Configuration of the relay station

[0059] 2-4. Configuration of the terminal apparatus

[0060] 3. Basic operation of the communication system

[0061] 3-1. Initial connection processing

[0062] 3-2. Random access procedure

[0063] 3-3. Details of the random access procedure in NR

[0064] 3-4. 2-step RACH in NR

[0065] 4. Operation of the communication system

[0066] 4-1. Summary of the spot cell determination means

[0067] 4-2. Details of the spot cell determination means

[0068] 5. Sequence example

[0069] 5-1. Spot cell determination means based on synchronization signal

[0070] 5-2. Spot cell determination means based on location information

[0071] 5-3. Spot cell determination means based on anchor cell

[0072] 6. Modification

[0073] 6-1. Function split

[0074] 6-2. Spot forming

[0075] 6-3. Reference signal

[0076] 6-4. Scheduling

[0077] 6-5. Other modifications

[0078] 7. Conclusion

[0079] <<1. SUMMARY>>

[0080] Before describing the embodiment in detail, an outline of the embodiment will be described.

[0081] <1-1. Problem>

[0082] In recent years, next-generation wireless communication has been discussed. In order to meet the requirements for achieving further improvements such as higher-speed communication, low-latency and high-reliability communication, massive / high-density communication, and simultaneous support for multiple items among these and above 5G NR, further improvement in frequency utilization efficiency is required. Techniques for improving frequency utilization efficiency include a publicly known technique of concentrating power at a specific place using a phase difference of a near field (hereinafter, simply referred to as power concentration technique).

[0083] The power concentration technique is expected to achieve more advanced spatial multiplexing. However, simply applying this technique to a radio access network will not necessarily be able to achieve wireless communication with high communication 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).

[0084] For example, in the case of achieving advanced spatial multiplexing by the power concentration technique, it is expected that there will be various problems such as frequent initial access occurring only by continuously using a conventional initial access procedure. In view of this, the present embodiment will examine a means for the initial access procedure when the power concentration technique is applied to a wireless communication network.

[0085] In the following description, the power concentration technique will be referred to as point forming in some cases.

[0086] <1-2. Power concentration technique (point forming)

[0087] Before describing an outline of the solution, the power concentration technique (point forming) will be described.

[0088] Figure 1 is a diagram for illustrating the power concentration technique (point forming). In conventional cellular mobile communication, a base station (e.g., eNB (eNodeB), gNB (gNodeB), or RAN node (including EUTRAN and NGRAN)) forms a planar or beam-like cell. In Figure 1 In the example of, the diagram on the left (classic cell) is a diagram illustrating a state in which the base station forms a planar cell, and the diagram in the center (beam forming) is a diagram illustrating a state in which the base station forms a beam-like cell. With this configuration, the base station provides communication to a terminal device (e.g., user equipment (UE)). In order to meet the requirements for achieving further improvements such as high-speed communication and low-latency and high-reliability communication of advanced technologies, the next-generation cellular communication is required to improve the frequency utilization efficiency to the limit.

[0089] Currently, a technology that forms a cell using a point (for example, a power concentration technology) is attracting attention. This is a technology that forms a point-like cell using cooperative control of a large number of transmission antennas, and is a technology that goes beyond spatial separation by conventional beamforming. In Figure 1 In an example, the right side of the figure (point forming) is a figure illustrating a state in which a base station forms a point-like cell. Hereinafter, this technology will be denoted as point forming, but can also be denoted by using other notations. While conventional beamforming cannot perform multiplexing of beam directions, point forming can achieve three-dimensional multiplexing. This achieves further enhancement of simultaneous communication of multiple terminals. In addition, point forming can also suppress interference with multiple terminals. This can improve the communication quality of the entire system, reduce the communication disconnection rate, and further enhance multi-connection communication.

[0090] Point forming is a technology based on the phase difference of individual radio waves transmitted from a large number of transmission antennas under consideration, and performs cooperative operation of a large number of transmission antennas to apply in-phase combination of radio waves at a specific place, thereby maximizing the received power at the specific place. Since the radio waves transmitted from a large number of transmission antennas are received at a random phase at a point other than the specific place, the received power is suppressed by averaging. This achieves point forming that forms a cell at a specific place. Here, in the phase difference control of the radio waves transmitted from a 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.

[0091] At this time, in the case of transmitting radio waves from a single transmission panel having a large number of transmission antenna elements, it is also allowed to consider the characteristics of the near field. Figure 2 is a figure illustrating the near field and the far field. A base station should conventionally communicate with a remote terminal device such as a smartphone. This leads to conventional research as shown on the right side of Figure 2 However, in the future, it is expected that communication using a larger transmission panel will be performed. This makes it possible to achieve communication that considers the phase difference as a near field region feature. Point forming can be utilized in the near field region. Figure 3 is a figure illustrating the Fraunhofer distance that defines the boundary between the near field and the far field.

[0092] Here, while the above describes an example of applying point forming in the near field, point forming can also be achieved in an environment where the phase difference can be considered. Therefore, in an environment that includes a large number of distributed antennas around the reception point, point forming can be performed regardless of the Fraunhofer distance. Figure 4 is a figure illustrating an example of point forming using a distributed antenna. In Figure 4 In an example, the base station includes a control unit (in Figure 4a control unit (in an example, a central unit (CU)) that controls multiple antennas, thereby controlling a transmission antenna. In Figure 4 In an example, the CU and the transmission antenna are optically connected, but are not necessarily optically connected. 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). Furthermore, the multiple antennas (multiple transmission points) can be one or more transmission panels that include multiple transmission antennas (antenna elements).

[0093] <1-3. Outline of the solution>

[0094] Based on the above, an outline of the solution of the present embodiment will be described.

[0095] Figure 5 is a diagram that illustrates an outline of the solution in the present embodiment. The communication system of the present embodiment includes a base station and a terminal device. In the drawing, a transmission point indicates a transmission antenna included in or controlled by the base station. A reception point indicates a reception antenna included in the terminal device.

[0096] The base station forms a point cell by a power concentration technique (point shaping). For example, the base station includes a control unit (in an example, a central unit (CU)) that controls multiple antennas. The base station performs cooperative control of the multiple antennas to concentrate power at a specific location, thereby forming a point cell. In Figure 5 In an example, the control unit (in an example, a central unit (CU)) controls multiple antennas, thereby controlling a transmission antenna. The base station performs cooperative control of the multiple antennas to concentrate power at a specific location, thereby forming a point cell. In Figure 5 In an example, the base station forms m x m point cells PC (point cells PC 11 to PC mn ) that cover an area surrounded by the transmission antenna.

[0097] The base station performs processing for determining a point cell to which a terminal device belongs. For example, the base station transmits multiple synchronization signals to the terminal device so that the terminal device identifies a point cell. Subsequently, the terminal device determines a point cell to which the terminal device belongs based on the synchronization signals. In Figure 5 In an example, the terminal device determines a point cell PC 54 to which the terminal device belongs. The base station can determine a point cell PC to which the terminal device belongs based on information from the terminal device.

[0098] Subsequently, the terminal device performs wireless communication using the determined point cell PC 54 .

[0099] In this way, in the present embodiment, the base station performs processing for determining a point cell to which a terminal device belongs. This enables the terminal device to efficiently access a point cell. This enables the communication system to achieve high communication performance.

[0100] The outline of the present embodiment is described above. Hereinafter, the communication system 1 of the present embodiment will be described in detail.

[0101] <<2. Configuration of communication system>>

[0102] First, the configuration of the communication system 1 will be described.

[0103] Figure 6 is a diagram illustrating an example of the configuration of the communication system 1 according to the present embodiment. The communication system 1 includes a management device 10, a base station 20, a relay station 30, and a terminal device 40. In a case where the individual wireless communication devices constituting the communication system 1 operate in cooperation with each other, the communication system 1 provides a wireless network in which a user can perform mobile communication. The wireless network of the present embodiment includes, for example, a radio access network RAN and a core network CN. In the present embodiment, a wireless communication device is a device having a wireless communication function, and in the present embodiment, the wireless communication device corresponds to the management device 10, the base station 20, the relay station 30, and the terminal device 40. Figure 6 In an example of, the device corresponds to the base station 20, the relay station 30, and the terminal device 40.

[0104] The communication system 1 can include a plurality of management devices 10, a plurality of base stations 20, a plurality of relay stations 30, and a plurality of terminal devices 40. In an example of, the communication system 1 includes the management devices 101 and 102 as the management device 10, and includes the base stations 201, 202, and 203 as the base station 20. In addition, the communication system 1 includes the relay stations 301 and 302 as the relay station 30, and includes the terminal devices 401, 402, and 403 as the terminal device 40. Figure 6

[0105] The terminal device 40 can be configured to connect to a network using a radio access technology (RAT) such as Long Term Evolution (LTE), New Radio (NR), 6G, Wi-Fi, or Bluetooth (registered trademark). At this time, the terminal device 40 can be configured to be able to use different radio access technologies (wireless communication methods). For example, the terminal device 40 can be configured to be able to use NR and Wi-Fi. In addition, the terminal device 40 can be configured to be able to use different cellular communication technologies (for example, LTE and NR, or 6G). LTE and NR are one type of cellular communication technology, and mobile communication of a terminal device is realized by using a cellular arrangement of a plurality of areas covered by a base station. 6G is also one type of cellular communication technology, and mobile communication of a terminal device is realized by using a cellular arrangement of a plurality of areas covered by a base station.

[0106] ​Hereinafter, it is assumed that "LTE" includes LTE-advanced (LTE-A), LTE-advanced Pro (LTE-A Pro), and evolved universal terrestrial radio access (EUTRA). In addition, it is assumed that NR includes new radio access technology (NRAT) and further EUTRA (FEUTRA). A single base station 20 can manage a plurality of cells. Hereinafter, a cell corresponding to LTE can be referred to as an LTE cell, and a cell corresponding to NR can be referred to as an NR cell.

[0107] NR is the next generation (fifth generation) radio access technology after LTE (fourth generation communication including LTE-advanced and LTE-advanced Pro). NR is a radio access technology that can support various use cases including enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and Ultra-Reliable and Low Latency Communications (URLLC). NR is standardized by Rel-15 of 3GPP (registered trademark) as a technical framework to support use scenarios, requirements, deployment scenarios, and the like in these use cases. In addition, 5G and above and 6G require simultaneous realization of high speed and large capacity, low latency / high reliability, and multiple simultaneous connections of multiple axes.

[0108] 6G is a cellular communication technology that is the next generation of NR or 5GS (5G system) of the fifth generation mobile communication, and includes a radio access technology and a network technology between a base station, a core network, and a data network. 6G can include technologies for realizing the complication of each technology for eMBB, mMTC, and URLLC, which have been defined as major use cases or requirements in NR (referred to as extreme connectivity), and new technologies for new aspects. For example, new technologies are expected to include technologies related to artificial intelligence (AI: including cognitive network, AI native air interface), sensing (including radar sensing, network as a sensor), and terahertz communication.

[0109] The wireless network can be compatible with a radio access technology (RAT) such as Long Term Evolution (LTE), New Radio (NR), and 6G. LTE, NR, and 6G are a type of cellular communication technology, and enable mobile communication of a terminal device by using a cellular arrangement of multiple areas covered by base stations. The radio access method used by the communication system 1 is not limited to LTE, NR, or 6G, but can be, for example, other radio access methods such as wideband code division multiple access (W-CDMA) and code division multiple access 2000 (cdma2000).

[0110] The base stations 20 and the relay stations 30 can each be a ground station or a non-ground station. The non-ground station can be a satellite station or an aircraft station. When the non-ground station is a satellite station, the wireless network can be a bent pipe (transparent) mobile satellite communication system.

[0111] In the present embodiment, a ground station (also referred to as a ground base station) refers to a base station or a relay station installed on the ground. The “ground” represents not only land but also a broad sense of a ground position, including underground, on water, and underwater. Note that in the following description, the description of the “ground station” can be referred to as a “gateway”.

[0112] A base station in LTE can be referred to as an evolved node B (eNodeB) or eNB. An NR base station can be referred to as a gNodeB or gNB. A 6G base station can be referred to as a 6G NB. In LTE, NR, and 6G, a terminal device (also referred to as a mobile station or a terminal) can be referred to as a user equipment (UE). The terminal device is a type of communication device, and is also referred to as a mobile station or a terminal.

[0113] The terminal device 40 can connect to a network using a radio access technology (wireless communication method) other than LTE, NR, 6G, Wi-Fi, or Bluetooth. For example, the terminal device 40 can connect to a network by using low power wide area (LPWA) communication. In addition, the terminal device 40 can connect to a network using wireless communication of a proprietary standard.

[0114] Here, the LPWA communication is wireless communication capable of realizing low power wide area communication. For example, the LPWA wireless is Internet of Things (IoT) wireless communication using a designated low power wireless (for example, a 920 MHz band) or an Industry-Science-Medical (ISM) band. The LPWA communication used by the terminal device 40 can conform to an LPWA standard. Examples of the LPWA standard include ELTRES, ZETA, SIGFOX, LoRaWAN, and NB-Iot. Of course, the LPWA standard is not limited to these, and can be another LPWA standard.

[0115] Figure 6 Each of the wireless communication devices in the communication system 1 can be regarded as a logically meaningful device. That is, a part of each of the wireless communication devices can be implemented by a virtual machine (VM), a container, Docker, or the like, and they can be physically implemented on the same hardware.

[0116] In the present embodiment, the concept of the "wireless communication device" includes not only a portable mobile device (terminal device) such as a mobile terminal, but also a device installed in a structure or a moving body. The structure or the moving body itself can be regarded as a wireless communication device. Furthermore, the concept of the wireless communication device includes not only the terminal device 40, but also the base station 20 and the relay station 30. The wireless communication device is a type of processing device and an information processing device. The wireless communication device can be alternatively called a transmission device or a reception device.

[0117] In the present embodiment, the resource refers to, for example, a frequency, a time, a resource element (including an REG, a CCE, a CORESET), a resource block, a bandwidth part, a component carrier, a symbol, a sub-symbol, a slot, a mini-slot, a sub-slot, a subframe, a frame, a PRACH occasion, an occasion, a code, a multiple access physical resource, a multiple access signature, and a subcarrier spacing (numerical parameters).

[0118] Hereinafter, the configuration of each of the individual wireless communication devices included in the communication system 1 will be specifically described. The configuration of each of the wireless communication devices illustrated below is only an example. The configuration of each of the wireless communication devices can be different from the configuration below.

[0119] <2-1. Configuration of Management Device>

[0120] The management apparatus 10 is an information processing apparatus (computer) that manages a wireless network. For example, the management apparatus 10 is an information processing apparatus that manages communication of the base station 20. For example, the management apparatus 10 can be a device having a function as a Mobility Management Entity (MME). The management apparatus 10 can be an apparatus having a function as an Access and Mobility Management Function (AMF) and / or a Session Management Function (SMF). The MME, the AMF, and the SMF are control plane network function nodes in a core network. The management apparatus 10 can be an apparatus having a function as a 6G control plane network function (6G CPNF). The 6G CPNF can include one or a plurality of logical nodes.

[0121] Of course, the function of the management apparatus 10 is not limited to the MME, the AMF, the SMF, or the 6G CPNF. The management apparatus 10 can be a device having a function as a Network Slice Selection Function (NSSF), an Authentication Server Function (AUSF), a Policy Control Function (PCF), or a Unified Data Management (UDM). In addition, the management apparatus 10 can be a device having a function as a Home Subscriber Server (HSS).

[0122] Note that the management apparatus 10 can have a function as a gateway. For example, the management apparatus 10 can have a function as a Serving Gateway (S-GW) or a Packet Data Network Gateway (P-GW). In addition, the management apparatus 10 can have a function as a User Plane Function (UPF). At this time, the management apparatus 10 can have a plurality of UPFs. The management apparatus 10 can be an apparatus having a function as a 6G control user plane network function (6G UPNF).

[0123] The core network includes a plurality of network functions. Each network function can be integrated into one physical device or distributed to a plurality of physical devices. That is, the management apparatus 10 can be arranged in a plurality of devices as a distributed arrangement. Furthermore, this distributed arrangement can be controlled to be executed dynamically. The base station 20 and the management apparatus 10 constitute a network, and provide a wireless communication service to the terminal apparatus 40. The management apparatus 10 is connected to the Internet, and the terminal apparatus 40 can use various services provided through the Internet via the base station 20.

[0124] Note that the management apparatus 10 does not necessarily have to be a device constituting the core network. For example, assume that the core network is a Wideband Code Division Multiple Access (W-CDMA) or Code Division Multiple Access 2000 (cdma2000) core network. At this time, the management apparatus 10 can be a device operating as a Radio Network Controller (RNC).

[0125] Figure 7 is a diagram illustrating a configuration of the management apparatus 10 according to the present embodiment. The management apparatus 10 includes a communication unit 11, a storage unit 12, and a control unit 13. Figure 7 The configuration shown in FIG. 1 is a functional configuration, and a hardware configuration can be different from this configuration. The functions of the management apparatus 10 can be implemented in a plurality of physically separate configurations in a static or dynamic distributed manner. The management apparatus 10 can be constituted by a plurality of server apparatuses.

[0126] The communication unit 11 is a communication interface for communicating with a wireless communication apparatus (for example, the base station 20 or the relay station 30). The communication unit 11 can be a network interface, or can be a device connection interface. The communication unit 11 can be a local area network (LAN) interface such as a network interface card (NIC), or can be a universal serial bus (USB) interface including a USB host controller, a USB port, and the like. The communication unit 11 can be a wired interface, or can be a wireless interface. The communication unit 11 operates as a communication means of the management apparatus 10. The communication unit 11 is controlled by the control unit 13.

[0127] The storage unit 12 is a readable / writable storage device such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, or a hard disk. The storage unit 12 functions as a storage means in the management apparatus 10. The storage unit 12 stores, for example, the connection state of the terminal apparatus 40. The storage unit 12 stores the radio resource control (RRC) state or the EPS connection management (ECM) state or the 5G system connection management (CM) state of the terminal apparatus 40. The storage unit 12 can function as a unit called a "home storage" (user information database) that stores the location information of the terminal apparatus 40.

[0128] The control unit 13 is a controller that controls individual components of the management apparatus 10. The control unit 13 can be implemented by, for example, a processor such as a central processing unit (CPU) or a micro processing unit (MPU). Specifically, the control unit 13 can be implemented by a processor that executes various programs stored in a storage device inside the management apparatus 10 using a random access memory (RAM) or the like as a work area. The 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). Further, the control unit 13 can be implemented by a Graphics Processing Unit (GPU). The CPU, the MPU, the ASIC, the FPGA, and the GPU can all be regarded as controllers. The control unit 13 can include a plurality of physically separate objects. For example, the control unit 13 can include a plurality of semiconductor chips.

[0129] <2-2. Configuration of base station>

[0130] The base station 20 is a wireless communication apparatus that performs wireless communication with other wireless communication apparatuses (for example, the relay station 30, the terminal apparatus 40, or another base station 20). The base station 20 can perform wireless communication with the terminal apparatus 40 via the relay station 30, or can directly perform wireless communication with the terminal apparatus 40.

[0131] The base station 20 is a device corresponding to a radio base station (base station, node B, eNB, gNB, or 6G NB, etc.) or a radio access point. The base station 20 can be a radio relay station. The base station 20 can be an optical link device called a Remote Radio Head (RRH). Furthermore, the base station 20 can be a receiving station such as a Field Pickup Unit (FPU). The base station 20 can be an Integrated Access and Backhaul (IAB) donor node or an IAB relay node that provides a radio access channel and a radio backhaul channel by using time division multiplexing, frequency division multiplexing, or space division multiplexing.

[0132] The radio access technology used by the base station 20 can be a cellular communication technology. The radio access technology used by the base station 20 can be a wireless LAN technology. For example, the radio access technology used by the base station 20 can be a Low-Power Wide-Area (LPWA) communication technology. Note that the radio access technology used by the base station 20 is not limited thereto, but can be another radio access technology. The wireless communication used by the base station 20 can be wireless communication using millimeter waves, or can be wireless communication using terahertz waves (THz waves). The wireless communication used by the base station 20 can be wireless communication using radio waves, or can be wireless communication using infrared rays or visible light (optical wireless communication). The base station 20 can be capable of Non-Orthogonal Multiple Access (NOMA) communication with the terminal device 40. Here, the NOMA communication refers to communication (transmission, reception, or both) using non-orthogonal resources. Note that the base station 20 can be capable of performing NOMA communication with another base station 20.

[0133] The base stations 20 can be capable of communicating with each other via a base station-core network interface (for example, an NG interface, an S1 interface, etc.). This interface can be implemented as a wired or wireless interface. Furthermore, the base stations can be capable of communicating with each other via an inter-base station interface (for example, an Xn interface, an X2 interface, an F1 interface, etc.). This interface can be implemented as a wired or wireless interface.

[0134] The base station (also referred to as a "base station device") conceptually includes not only a donor base station but also a relay base station (also referred to as a "relay station"). The relay base station can be any one of an RF repeater, a smart repeater, and a smart surface. The base station conceptually includes not only a structure having the functions of a base station but also a device installed in the structure.

[0135] Examples of the structure include a building such as a high-rise building, a house, a steel tower, a station facility, an airport facility, a port facility, an office building, a school building, a hospital, a factory, a commercial facility, or a stadium. The structure conceptually includes not only a building but also a non-building structure such as a tunnel, a bridge, a dam, a fence, and a steel column, and a facility such as a crane, a gate, and a windmill. The structure conceptually includes not only a land-based (narrowly, ground-based) structure or an underground structure but also a water-based structure such as a wharf or a giant floating body, and an underwater structure such as an ocean observation facility. The base station can also be referred to as an information processing apparatus.

[0136] The base station 20 can be a donor station or a relay station. The base station 20 can be a fixed station or a mobile station. A mobile station is a wireless communication apparatus (for example, a base station) configured to be movable. At this time, the base station 20 can be a device mounted on a moving body, or can be the moving body itself. For example, a relay station having mobility can be regarded as a base station 20 as a mobile station. Further, a device designed to have mobility and having a function (at least a part of a function) of a base station, for example, an unmanned aerial vehicle (UAV) represented by a drone or a smart phone, also corresponds to a base station 20 as a mobile station.

[0137] Here, the moving body can be a mobile terminal such as a smart phone or a mobile phone. The moving body can be a moving body moving on land (narrowly, on the ground) (for example, a vehicle such as a car, a motorcycle, a bus, a truck, a motorbike, a train, or a linear motor car), or a moving body moving underground (for example, by a tunnel) (for example, a subway). The moving body can be a moving body moving on water (for example, a ship such as a passenger ship, a cargo ship, or a hovercraft), or a moving body moving underwater (for example, a diving boat such as a deep-sea submersible, a submarine, or an unmanned submarine). The moving body can be a moving body moving in the atmosphere (for example, an aircraft such as an airplane, a dirigible, or a drone).

[0138] The base station 20 can be a ground base station (a ground station) mounted on the ground. The base station 20 can be a base station arranged on a structure on the ground, or can be a base station mounted in a moving body moving on the ground. The base station 20 can be an antenna mounted in a structure such as a building and a signal processing apparatus connected to the antenna. The base station 20 can be the structure or the moving body itself. The "ground" represents not only land (narrowly, the ground) but also a general ground position including underground, on water, and underwater. The base station 20 is not limited to a ground base station. In the case where the communication system 1 is a satellite communication system, the base station 20 can be an aircraft station. From the perspective of a satellite station, an aircraft station located on the Earth is a ground station.

[0139] The base station 20 is not limited to a terrestrial station. The base station 20 can be a non-terrestrial base station (non-terrestrial station) capable of floating in the air or space. For example, the base station 20 can be an aircraft station or a satellite station.

[0140] The satellite station is a satellite station capable of floating outside the atmosphere. The satellite station can be a device installed on a space mobile body such as a man-made satellite, or can be the space mobile body itself. The space mobile body is a mobile body that moves outside the atmosphere. Examples of the space mobile body include man-made bodies such as a man-made satellite, a spacecraft, a space station, or a probe. The satellite serving as the satellite station can be any one of a low earth orbiting (LEO) satellite, a medium earth orbiting (MEO) satellite, a geostationary earth orbiting (GEO) satellite, or a highly elliptical orbiting (HEO) satellite. The satellite station can be a device installed on a low earth orbiting satellite, a medium earth orbiting satellite, a geostationary earth orbiting satellite, or a highly elliptical orbiting satellite.

[0141] The aircraft station is a wireless communication device capable of floating in the atmosphere, such as an aircraft. The aircraft station can be a device installed on an aircraft or the like, or can be the aircraft itself. The aircraft conceptually includes not only heavy aircraft such as an airplane or a glider, but also light aircraft such as a balloon and an airship. The aircraft conceptually includes not only heavy aircraft or light aircraft, but also rotorcraft such as a helicopter or an autogyro. The aircraft station or the aircraft equipped with the aircraft station can be an unmanned aerial vehicle such as a drone.

[0142] The unmanned aerial vehicle conceptually includes an unmanned aircraft system (UAS) and a tethered UAS. The unmanned aircraft conceptually further includes a Lighter-than-Air (LTA) unmanned aircraft system (UAS) and a Heavier-than-Air (HTA) unmanned aircraft system (UAS). The unmanned aircraft conceptually further includes a High Altitude UAS platform (HAP).

[0143] The coverage of the base station 20 can be relatively large, such as a macro cell, or can be relatively small, such as a pico cell. The coverage of the base station 20 can be extremely small, such as a femto cell. The base station 20 can have a beamforming function. In this case, the base station 20 can form a cell or a service area for each beam. The base station 20 can also include a point forming function. Point forming is a technique that concentrates power in a specific place using a phase difference of near field (power concentration technique). In this case, the base station 20 can form a cell or a service area for each point.

[0144] Figure 8 is a diagram illustrating a configuration of the base station 20 according to the present embodiment. The base station 20 includes a wireless communication unit 21, a storage unit 22, and a control unit 23. Figure 8 The configuration shown in FIG. 1 is a functional configuration, and a hardware configuration can differ from this configuration. Furthermore, the functions of the base station 20 can be implemented in a distributed form in a plurality of physically separate configurations.

[0145] The wireless communication unit 21 is a signal processing unit for performing wireless communication with other wireless communication devices (for example, the relay station 30, the 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. The wireless communication unit 21 can support W-CDMA, cdma2000, and the like in addition to NR, LTE, and 6G. The wireless communication unit 21 can support an automatic retransmission technique such as Hybrid Automatic Repeat Request (HARQ).

[0146] The wireless communication unit 21 includes a transmission processing unit 211, a reception processing unit 212, and an antenna 213. The wireless communication unit 21 can include a plurality of transmission processing units 211, a plurality of reception processing units 212, and a plurality of antennas 213. In a case where the wireless communication unit 21 supports a plurality of radio access schemes, individual parts of the wireless communication unit 21 can be configured separately for each radio access scheme. The transmission processing unit 211 and the reception processing unit 212 can be configured separately for LTE, NR, and 6G. The antenna 213 can include a plurality of antenna elements, such as a plurality of patch antennas. The wireless communication unit 21 can have a beamforming function. For example, the wireless communication unit 21 can have a polarization beamforming function using a vertical polarization wave (V-polarization wave) and a horizontal polarization wave (H-polarization wave) (or can have a polarization beamforming function using dual polarization in polarization directions that are 45 degrees and -45 degrees from the vertical direction). The wireless communication unit 21 can also include a point forming function.

[0147] 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 the downlink data input from the control unit 23 by using an encoding method such as block coding, convolutional coding, or turbo coding. The encoder can perform encoding using a polar code or a Low Density Parity Check (LDPC) code. The transmission processing unit 211 modulates the encoded bits by a predetermined modulation scheme such as BPSK, QPSK, 16QAM, 64QAM, or 256QAM. In this case, signal points on a 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 of each channel and a downlink reference signal, and allocates the multiplexed signal to a predetermined resource element. Subsequently, the transmission processing unit 211 performs various types of signal processing on the multiplexed signal. For example, the transmission processing unit 211 performs processing such as conversion to a frequency domain using a fast Fourier transform, addition of a guard interval (cyclic prefix), generation of a baseband digital signal, conversion to an analog signal, quadrature modulation, up-conversion of frequency, removal of unnecessary frequency components, and power amplification. The signal generated by the transmission processing unit 211 is transmitted from the antenna 213.

[0148] The reception processing unit 212 processes the uplink signal received via the antenna 213. For example, the reception processing unit 212 performs processes such as down-conversion, removal of unnecessary frequency components, amplification level control, quadrature demodulation, conversion to a digital signal, removal of a guard interval (cyclic prefix), and frequency-domain signal extraction using a fast Fourier transform on the uplink signal. Then, the reception processing unit 212 de-multiplexes an uplink channel such as a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH) and an uplink reference signal from the signal subjected to these processes. Subsequently, the reception processing unit 212 demodulates the received signal using a modulation scheme such as binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK) with respect to the modulation symbols of the uplink channel. The modulation scheme used in the demodulation can be 16 quadrature amplitude modulation (QAM), 64 QAM, or 256 QAM. 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 reception processing unit 212 performs a decoding process on the encoded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the control unit 23.

[0149] The antenna 213 is an antenna device that performs mutual conversion of electric currents and radio waves. The antenna 213 can include one antenna element, for example, one patch antenna. In addition, the antenna 213 can include a plurality of antenna elements (for example, a plurality of patch antennas). In the case where the antenna 213 includes a plurality of antenna elements, the wireless communication unit 21 can have a beamforming function. In this case, the wireless communication unit 21 can control the directivity of radio signals using the plurality of antenna elements to generate a directional beam. In the case where the antenna 213 includes a plurality of antenna elements, the wireless communication unit 21 can have a point forming function. At this time, the wireless communication unit 21 can be configured to perform cooperative control of the plurality of antenna elements to form a point-like cell.

[0150] The antenna 213 can be a dual-polarized antenna. In a case where the antenna 213 is a dual-polarized antenna, the wireless communication unit 21 can use a vertically polarized wave (V-polarized wave) and a horizontally polarized wave (H-polarized wave) (or dual-polarized waves in polarization directions of 45 degrees and -45 degrees from the vertical direction) in wireless signal transmission. The wireless communication unit 21 can control the directivity of a wireless signal transmitted using the vertically polarized wave and the horizontally polarized wave (or dual-polarization in polarization directions of 45 degrees and -45 degrees from the vertical direction). Further, the wireless communication unit 21 can transmit and receive spatially multiplexed signals via a plurality of layers including a plurality of antenna elements.

[0151] The storage unit 22 is a readable / writable storage device such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage unit 22 operates as a storage means in the base station 20.

[0152] The control unit 23 is a controller that controls individual portions of the base station 20. The control unit 23 controls the wireless communication unit to perform wireless communication with another wireless communication apparatus (for example, the relay station 30, the terminal apparatus 40, or another base station 20). The control unit 23 can be implemented by a processor such as a CPU or an MPU. Specifically, the control unit 23 can be implemented by a processor that executes various programs stored in a storage device inside the base station 20 using a RAM or the like as a work area. The control unit 23 can be implemented by an integrated circuit such as an ASIC or an FPGA. The control unit 23 can be implemented by a GPU. The CPU, the MPU, the ASIC, the FPGA, and the GPU can all be regarded as controllers. The control unit 23 can include a plurality of physically separate objects. For example, the control unit 23 can include a plurality of semiconductor chips.

[0153] The control unit 23 includes an acquisition unit 231, a formation unit 232, a determination processing unit 233, a connection processing unit 234, and a measurement unit 235. The individual blocks (the acquisition unit 231 to the measurement unit 235) that constitute the control unit 23 are functional blocks that indicate the functions of the control unit 23, respectively. These functional blocks can be software blocks or hardware blocks. For example, each of the above-described functional blocks can be one software module implemented by software (including microprograms) or one circuit block on a semiconductor chip (a die). Of course, each of the functional blocks can be formed as one processor or one integrated circuit. Note that the control unit 23 can be configured in a functional unit different from the above-described functional blocks. The functional blocks can be configured by using any method.

[0154] In some embodiments, the base station 20 can be configured by a set of multiple physical or logical devices. As an example, the base station 20 in the present embodiment can be classified into a plurality of devices, such as a Baseband Unit (BBU) and a Radio Unit (RU). The base station 20 can be interpreted as a set of multiple devices. Also, the base station can be one or both of the BBU and the RU. The BBU and the RU can be connected to each other via a predetermined interface (e.g., enhanced Common Public Radio Interface (eCPRI)).

[0155] The RU can be referred to as a Remote Radio Unit (RRU) or a Radio DoT (RD). The RU can support a gNB Distributed Unit (gNB-DU) described below. The BBU can support a gNB Central Unit (gNB-CU) described below. The RU can be a device integrally formed with an antenna. For example, the antenna (e.g., an antenna integrally formed with the RU) of the base station 20 can employ an advanced antenna system, and support MIMO (e.g., FD-MIMO) or beamforming. Also, the antenna of the base station 20 can support point forming. For example, the antenna of the base station 20 can include 64 transmission antenna ports and 64 reception antenna ports.

[0156] The antenna mounted on the RU can be an antenna panel including 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, a horizontally polarized antenna panel and a vertically polarized antenna panel. The RU can be equipped with two types of antenna panels, a right circularly polarized antenna panel and a left circularly polarized antenna panel, or an antenna panel having a polarization direction of 45 degrees from the vertical direction and an antenna panel having a polarization direction of -45 degrees from the vertical direction. Multiple antennas having multiple polarization directions can be mounted on one antenna panel. The RU can form and control independent beams for each antenna panel.

[0157] A plurality of base stations 20 can be connected to each other. One or more base stations 20 can be included in a Radio Access Network (RAN). That is, a base station 20 can be referred to simply as a RAN, a RAN node, an Access Network (AN), an AN node, and the like. A RAN in LTE is sometimes referred to as an Enhanced Universal Terrestrial RAN (EUTRAN). A RAN in NR can be referred to as an NGRAN. Also, a RAN in 6G can be referred to as a 6GRAN. A RAN in W-CDMA (UMTS) can be referred to as a UTRAN.

[0158] A base station 20 in LTE can be referred to as an evolved Node B (eNodeB) or eNB. That is, an EUTRAN includes one or more eNodeBs (eNBs). An NR base station 20 can be referred to as a gNodeB or gNB. At this time, an NGRAN contains one or more gNBs. A 6G base station can be referred to as a 6GNodeB, 6gNodeB, 6GNB, or 6gNB. At this time, a 6GRAN contains one or more 6GNBs. An EUTRAN can include a gNB (en-gNB) connected to a core network (EPC) in an LTE communication system (EPS). An NGRAN can include an ng-eNB connected to a core network 5GC in a 5G communication system (5GS).

[0159] When the base station 20 is an eNB, gNB, 6GNB, or the like, the base station 20 can be referred to as a 3GPP access. When the base station 20 is a radio access point, the base station 20 can be referred to as a non-3GPP access. The base station 20 can be an optical link device called a remote radio head (RRH). Also, in the case where the base station 20 is a gNB, the base station 20 can be a combination of the gNB-CU and the gNB-DU described above, or can be any one of the gNB-CU and the gNB-DU.

[0160] Here, for communication with the UE, the gNB-CU hosts multiple upper layers (e.g., Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP)) in the access stratum. On the other hand, the gNB-DU hosts multiple lower layers (e.g., Radio Link Control (RLC), Medium Access Control (MAC), and Physical Layer (PHY)) in the access stratum. That is, in the messages / information to be 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 the remaining configurations can be generated by the gNB-CU. These configurations can be transmitted and received via the F1 interface described below.

[0161] The base stations 20 can be configured to be able to communicate with another base station. When the plurality of base stations 20 are eNBs or a combination of eNBs and en-gNBs, the base stations 20 can be connected through an X2 interface. When the plurality of base stations 20 are gNBs or a combination of gn-eNBs and gNBs, the base stations 20 can be connected through an Xn interface. When the plurality of base stations 20 are a combination of gNB-CUs and gNB-DUs, the base stations 20 can be interconnected through the F1 interface described above. For example, the messages / information to be described below (e.g., RRC signaling, MAC control element (MAC CE), downlink control information (DCI), etc.) can be transmitted between the plurality of base stations 20 via an interface such as the X2 interface, the Xn interface, the F1 interface.

[0162] A cell provided by the base station 20 can be referred to as a serving cell. The serving cell conceptually includes a primary cell (PCell) and a secondary cell (SCell). When dual connectivity is provided to the terminal device 40, the PCell provided by a master node (MN) and zero or one or more SCells can be referred to as a master cell group. Examples of dual connectivity include EUTRA-EUTRA dual connectivity, EUTRA-NR dual connectivity (ENDC), ENDC with 5GC, NR-EUTRA dual connectivity (NEDC), and NR-NR dual connectivity, and so on. Examples of dual connectivity also include NR-6G dual connectivity and 6G-NR dual connectivity.

[0163] A serving cell can include a primary secondary cell or a primary SCell (PSCell). In the case where dual connectivity is provided to the terminal device 40, the PSCell and zero or one or more SCells provided by a secondary node (SN) can be referred to as a secondary cell group (SCG). A physical uplink control channel (PUCCH) is transmitted by the PCell and the PSCell, but not by the SCell, unless specially configured (e.g., PUCCH on SCell). Radio link failure is also detected by the PCell and the PSCell, but not by the SCell (not required to detect). In this way, since the PCell and the PSCell have a special role in the serving cell, these cells are also referred to as special cells (SpCell).

[0164] One cell can be associated with one downlink component carrier and one uplink component carrier. The system bandwidth corresponding to one cell can be divided into a plurality of bandwidth parts (BWPs). In this case, one or more BWPs can be configured for the terminal device 40, and one BWP can be used for the terminal device 40. The radio resources (e.g., frequency band, numerology (subcarrier spacing), and slot format (slot configuration)) that the terminal device 40 can use can be different for each cell, each component carrier, or each BWP.

[0165] <2-3. Configuration of a relay station>

[0166] The relay station 30 is a wireless communication device that functions as a repeater of the base station 20. The relay station 30 is a type of base station. The relay station 30 is a type of information processing device. The relay station 30 can also be referred to as a relay base station. For example, the relay station 30 can be a device called a repeater (e.g., an RF repeater, a smart repeater, or a smart surface). The relay station 30 is a wireless communication device that performs wireless communication with other wireless communication devices (e.g., the base station 20, another relay station 30, or the terminal device 40).

[0167] The relay station 30 can be capable of performing NOMA communication with the terminal device 40. The relay station 30 relays communication between the base station 20 and the terminal device 40. The relay station 30 can be capable of performing wireless communication with another relay station 30 and the base station 20. The relay station 30 can be a ground station device or a non-ground station device. The relay station 30 constitutes a radio access network RAN together with the base station 20.

[0168] The relay station 30 can be a fixed device, a movable device, or a floating device. The size of the coverage range of the relay station 30 is not limited to a particular size. The cell covered by the relay station 30 can be a macro cell, a micro cell, or a small cell.

[0169] The relay station 30 can be installed on any type of device as long as the function of relaying is satisfied. The relay station 30 can be installed on a terminal device such as a smartphone, can be installed on a car, a train, or a human-powered vehicle, can be installed on a balloon, an airplane, or a drone, or can be installed on a home appliance such as a television, a game machine, an air conditioner, a refrigerator, or a lighting device.

[0170] The configuration of the relay station 30 can be similar to that of the base station 20 described above. Like the base station 20 described above, the relay station 30 can be a device installed on a moving body, or can be the moving body itself. Here, the moving body can be a mobile terminal such as a smartphone or a mobile phone, as described above. The moving body can be a moving body that moves on land (ground in a narrow sense), or can be a moving body that moves underground. The moving body can be a moving body that moves on the surface of water, or can be a moving body that moves underwater. The moving body can be a moving body that moves inside the atmosphere, or can be a moving body that moves outside the atmosphere. The relay station 30 can be a ground station device or a non-ground station device. The relay station 30 can be an aircraft station or a satellite station.

[0171] Similar to the base station 20, the coverage of the relay station 30 can be large, such as a macro cell, or small, such as a pico cell. The coverage of the relay station 30 can be extremely small, such as a femto cell. The relay station 30 can have a beamforming function. In this case, the relay station 30 can form a cell or a service area for each beam. The relay station 30 can also include a point forming function. In this case, the relay station 30 can form a cell or a service area for each point.

[0172] Figure 9 Fig. 2 is a diagram illustrating a configuration of the relay station 30 according to the present embodiment. The relay station 30 includes a wireless communication unit 31, a storage unit 32, and a control unit 33. Figure 9 The configuration illustrated in Fig. 2 is a functional configuration, and a hardware configuration can differ from this configuration. Furthermore, the functions of the relay station 30 can be implemented in a distributed manner in a plurality of physically separate configurations.

[0173] The wireless communication unit 31 is a signal processing unit for performing wireless communication with other wireless communication devices, such as the base station 20, the 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 support W-CDMA, cdma3000, and the like.

[0174] The wireless communication unit 31 includes a transmission processing unit 311, a reception processing unit 312, and an antenna 313. The wireless communication unit 31 can include a plurality of transmission processing units 311, a plurality of reception processing units 312, and a plurality of antennas 313. In a case where the wireless communication unit 31 supports a plurality of radio access schemes, individual parts of the wireless communication unit 31 can be configured separately for each radio access scheme. The transmission processing unit 311 and the reception processing unit 312 can be configured separately for LTE, NR, and 6G. The configurations of the transmission processing unit 311, the reception processing unit 312, and the antenna 313 can be similar to those of the transmission processing unit 211, the reception processing unit 212, and the antenna 213 of the base station 20 described above, respectively. Similar to the wireless communication unit 21 of the base station 20, the wireless communication unit 31 can have a beamforming function. Similar to the wireless communication unit 21 of the base station 20, the wireless communication unit 31 can have a point forming function.

[0175] The storage unit 32 is a readable / writable storage device, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage unit 32 operates as a storage means in the relay station 30. The configuration and functions of the storage unit 32 can be similar to those of the storage unit 22 of the base station 20 described above.

[0176] The control unit 33 is a controller that controls individual sections of the relay station 30. The control unit 33 can be implemented by a processor such as a CPU or an MPU. Specifically, the control unit 33 is implemented by a processor using a RAM or the like as a work area, executing various programs stored in a storage device inside the relay station 30. The control unit 33 can be implemented by an integrated circuit such as an ASIC or an FPGA. The CPU, the MPU, the ASIC, and the FPGA can all be regarded as controllers. The control unit 33 can be implemented by a GPU. The CPU, the MPU, the ASIC, the FPGA, and the GPU can all be regarded as controllers. The control unit 33 can include a plurality of physically separate objects. For example, the control unit 33 can include a plurality of semiconductor chips. The configuration and the functions of the control unit 33 can be similar to those of the control unit 23 of the base station 20 described above.

[0177] The control unit 33 includes an acquisition unit 331, a formation unit 332, a determination processing unit 333, a connection processing unit 334, and a measurement unit 335. The individual blocks (the acquisition unit 331 to the measurement unit 335) that constitute the control unit 33 are functional blocks that indicate the functions of the control unit 33, respectively. These functional blocks can be software blocks or hardware blocks. For example, each of the functional blocks described above can be one software module implemented by software (including microprograms) or one circuit block on a semiconductor chip (a die). Of course, each of the functional blocks can be formed as one processor or one integrated circuit. Note that the control unit 33 can be configured in a functional unit different from the functional blocks described above. The functional blocks can be configured by using any method.

[0178] Note that the relay station 30 can be an IAB relay node. The relay station 30 operates as an IAB-mobile termination (IAB-MT) of an IAB-donor node that provides a backhaul, and operates as an IAB-distributed unit (IAB-DU) of the terminal device 40 that provides an access. The IAB-donor node can be the base station 20, for example, and operates as an IAB-Central Unit (IAB-CU).

[0179] <2-4. Configuration of terminal device>

[0180] The terminal device 40 is a wireless communication device that performs wireless communication with another wireless communication device (e.g., the base station 20, the relay station 30, or another terminal device 40, etc.). The terminal device 40 can be implemented by employing any form of information processing device (computer). For example, the terminal device 40 can be a mobile terminal such as a mobile phone, a smart device (smartphone or tablet device), a personal digital assistant (PDA), or a laptop PC. The terminal device 40 can be an imaging device (e.g., a video camera) having a communication function. The terminal device 40 can be a motorcycle, a mobile relay vehicle, or the like equipped with a communication device such as a field pickup unit (FPU). The terminal device 40 can be a machine to machine (M2M) device or an Internet of Things (IoT) device. The terminal device 40 can be a wearable device such as a smart watch.

[0181] The 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. At this time, the xR device can be a glasses-type device such as AR glasses or MR glasses, or can be a head-mounted device such as a VR head-mounted display. In a case where the terminal device 40 is an xR device, the terminal device 40 can be a stand-alone device including only a portion (e.g., a glasses portion) to be worn on a user. Further, the terminal device 40 can be a terminal-linked device including a portion (e.g., a glasses portion) to be worn on a user and a terminal portion (e.g., a smart device) linked to the portion to be worn on the user.

[0182] The terminal device 40 can be capable of performing NOMA communication with the base station 20. The terminal device 40 can be capable of using an automatic retransmission technique such as HARQ when communicating with the base station 20. The terminal device 40 can be capable of performing sidelink communication with another terminal device 40. The terminal device 40 can be capable of using an automatic retransmission technique such as HARQ when performing sidelink communication. The terminal device 40 can be capable of performing NOMA communication when performing sidelink communication with another terminal device 40. The terminal device 40 can be capable of performing LPWA communication with another wireless communication device such as the base station 20. The wireless communication used by the terminal device 40 can be wireless communication using millimeter waves. The wireless communication (including sidelink communication) used by the terminal device 40 can be wireless communication using radio waves, or wireless communication using infrared rays or visible light, i.e., optical wireless communication.

[0183] The terminal device 40 can be a mobile wireless communication device, i.e., a mobile device. Furthermore, the terminal device 40 can be a wireless communication device mounted on a mobile body, or can be the mobile body itself. The terminal device 40 can be a vehicle that moves on a road, such as a car, a bus, a truck, or a motorcycle, or can be a wireless communication device mounted on a vehicle. The mobile body can be a mobile terminal, or can be a mobile body that moves on land (in a narrow sense, on the ground), under the ground, on water, or under water. The mobile body can be a mobile body that moves inside the atmosphere, such as an aircraft, an airship, a balloon, or a helicopter, or can be a mobile body that moves outside the atmosphere, such as an artificial satellite. The mobile body can be an unmanned aerial vehicle (UAV), such as a drone. The terminal device 40 can be a wireless communication device mounted on a mobile body.

[0184] The terminal device 40 can be capable of performing communication while being connected to a plurality of base stations 20 or a plurality of cells at the same time. For example, when one base station 20 supports a communication area via a plurality of cells (e.g., a pCell and an sCell), the plurality of cells can be combined by using a carrier aggregation (CA) technique, a dual connectivity (DC) technique, or a multi-connectivity (MC) technique, and communication is performed between the base station 20 and the terminal device 40. Alternatively, the terminal device 40 and the plurality of base stations 20 can communicate with each other via cells of different base stations 20 by a coordinated multi-point transmission and reception (CoMP) technique.

[0185] The terminal device 40 can be a relay terminal that relays communication to a remote terminal.

[0186] Figure 10 is a diagram illustrating a configuration of the terminal device 40 according to the present embodiment. The terminal device 40 includes a wireless communication unit 41, a storage unit 42, and a control unit 33. Figure 10 The configuration shown in the above is a functional configuration, and a hardware configuration can be different from this configuration. Furthermore, the functions of the terminal device 40 can be implemented in a distributed manner in a plurality of physically separate configurations.

[0187] The wireless communication unit 41 is a signal processing unit for performing wireless communication with other wireless communication apparatuses (e.g., the base station 20, the relay station 30, and another terminal apparatus 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. The wireless communication unit 41 can support W-CDMA, cdma2000, and the like in addition to NR, LTE, and 6G. The wireless communication unit 41 can support an automatic retransmission technique such as Hybrid Automatic Repeat reQuest (HARQ).

[0188] The wireless communication unit 41 includes a transmission processing unit 411, a reception processing unit 412, and an antenna 413. The wireless communication unit 41 can include a plurality of transmission processing units 411, a plurality of reception processing units 412, and a plurality of antennas 413. In a case where the wireless communication unit 41 supports a plurality of radio access schemes, individual parts of the wireless communication unit 41 can be respectively configured for each radio access scheme. The transmission processing unit 411 and the reception processing unit 412 can be respectively configured for LTE, NR, and 6G. The antenna 413 can include a plurality of antenna elements, e.g., a plurality of patch antennas. The wireless communication unit 41 can have a beamforming function. For example, the wireless communication unit 41 can have a polarization beamforming function using vertical polarization waves (V-polarization waves) and horizontal polarization waves (H-polarization waves) (or can have a polarization beamforming function using dual polarization in polarization directions that are 45 degrees and -45 degrees from the vertical direction). The wireless communication unit 41 can also include a point forming function.

[0189] The storage unit 42 is a readable / writable storage device such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage unit 42 operates as a storage means in the terminal apparatus 40.

[0190] The control unit 43 is a controller that controls individual parts of the terminal apparatus 40. The control unit 43 controls the wireless communication unit to perform wireless communication with another wireless communication apparatus (e.g., the base station 20, the relay station 30, or another terminal apparatus 40). The control unit 43 can be implemented by a processor such as a CPU or an MPU. Specifically, the control unit 43 is implemented by a processor that executes various programs stored in a storage device inside the terminal apparatus 40 using a RAM or the like as a work area. The control unit 43 can be implemented by an integrated circuit such as an ASIC or an FPGA. The CPU, the MPU, the ASIC, and the FPGA can all be regarded as controllers. The control unit 43 can be implemented by a GPU. The CPU, the MPU, the ASIC, the FPGA, and the GPU can all be regarded as controllers. The control unit 43 can include a plurality of physically separate objects. For example, the control unit 43 can include a plurality of semiconductor chips.

[0191] The control unit 43 includes a determination processing unit 431 and a communication control unit 432. The individual blocks (determination processing unit 431 to communication control unit 432) constituting the control unit 43 are functional blocks indicating the functions of the control unit 43, respectively. These functional blocks can be software blocks or hardware blocks. For example, each of the above-described functional blocks can be a software module realized by software (including microprogram) or a circuit block on a semiconductor chip (die). Of course, each of the functional blocks can be formed as a processor or an integrated circuit. Note that the control unit 43 can be configured in a functional unit different from the above-described functional blocks. The functional blocks can be configured by using any method.

[0192] <<3. Basic operation of communication system>>

[0193] The configuration of the communication system 1 has been described above. Before describing the operation of the communication system 1 to solve the problem of the present embodiment, the basic operation of the communication system 1 will be described.

[0194] In the following description, the base station 20 can be referred to as a gateway. Further, the base station 20 can be understood as a relay station 30.

[0195] <3-1. Initial connection processing>

[0196] First, the initial connection processing will be described.

[0197] The initial connection processing is processing for transitioning the wireless connection state of the terminal device 40 from an unconnected state to a connected state. The unconnected state includes, for example, RRC_IDLE and RRC_INACTIVE. RRC_IDLE is an idle state in which the terminal device is not connected to any cell, and is also referred to as an idle mode. Further, RRC_INACTIVE is a radio connection state indicating a newly defined inactive state in NR, and is also referred to as an inactive mode. In RRC_INACTIVE, an RRC connection itself is not established between the terminal device 40 and the base station, but the terminal device 40 and the base station can each hold a state in which some UE context is retained. The terminal device 40 and the base station can use the retained UE context to speed up repeated transition of the terminal device 40 to the connected state. The unconnected state can include a lightning mode. Examples of the connected state include RRC_CONNECTED. RRC_CONNECTED is a connected state in which the terminal device establishes a connection with a specific cell (for example, a primary cell), and is also referred to as a connected mode.

[0198] Figure 11 is a flowchart illustrating an example of the initial connection processing. The initial connection processing will be described below with reference to Figure 11 The initial connection processing described below is, for example, performed when the terminal device 40 is powered on.

[0199] First, the terminal device 40 in the unconnected state performs a cell selection procedure (cell search). The cell selection procedure (cell search) is a procedure in which a user equipment (UE) detects a physical cell ID (PCI) of a cell and acquires time and frequency synchronization. The cell search of the present embodiment includes steps of detecting a synchronization signal and decoding a Physical Broadcast Channel (PBCH). The terminal device 40 detects a synchronization signal of a cell (step S11).

[0200] The terminal device 40 performs synchronization with the cell in the downlink based on the detected synchronization signal. Subsequently, after establishment of downlink synchronization, the terminal device 40 attempts to decode the PBCH and acquire a Master Information Block (MIB) as part of system information (step S12).

[0201] System information is information that announces settings in a cell that transmits system information. System information can be information that is common to all terminal devices belonging to the cell, including the terminal device 40. System information can be information that is unique to the cell. System information includes, for example, information on cell access, information on cell selection, and information on other RATs and other systems. System information includes an MIB and System Information Blocks (SIBs). The MIB is information necessary to receive SIBs and the like, and is a fixed payload size of information announced by the PBCH. The MIB includes information of a part of a system frame number, at least SIB1, and subcarrier spacing of Msg.2 / 4 for initial connection and paging and broadcast SI messages, subcarrier offset information, DMRS Type A position information, PDCCH configuration for at least SIB1, cell barring (cell screening) information, and intra-frequency reselection information. The SIB is system information other than the MIB and is announced by the PDSCH.

[0202] System information can be classified into first system information, second system information, and third system information. The first system information and the second system information include information on cell access, information on acquisition of other system information, and information on cell selection. Information included in the MIB is the first system information. Among the SIBs, information included in SIB1 is the second system information (e.g., remaining minimum SI). Remaining system information is the third system information (e.g., other SI).

[0203] Also in NR, system information is announced from an NR cell. A physical channel carrying the system information can be transmitted in a slot or a mini-slot. A mini-slot is defined by a number of symbols that is smaller than that of a slot. Since the physical channel carrying the system information is transmitted in a mini-slot, time required for beam sweeping can be reduced, thereby reducing overhead. In NR, first system information is transmitted on an NR-PBCH, and second system information is transmitted on a physical channel different from the NR-PBCH.

[0204] The terminal device 40 acquires the second system information based on the MIB (i.e., the first system information) (step S13). As described above, the second system information includes SIB1 and SIB2.

[0205] The SIB1 includes cell access control information and scheduling information about system information other than the SIB1. In the case of NR, the SIB1 includes information about cell selection (e.g., cellSelectionInfo), information about cell access (e.g., cellAccessRelatedInfo), information about connection establishment failure control (e.g., connEstFailureControl), scheduling information about system information other than the SIB1 (e.g., si-SchedulingInfo), and serving cell configuration. The serving cell configuration includes cell-specific parameters, and includes downlink configuration, uplink configuration, and TDD configuration information. The uplink configuration includes RACH configuration, and the like. Further, in the case of LTE, the SIB1 includes cell access information, cell selection information, maximum uplink transmission power information, TDD configuration information, periodicity of system information, system information mapping information, and system information (SI) window length.

[0206] In the case of NR, the SIB2 includes cell reselection information (e.g., cellReselectionInfoCommon) and cell reselection serving frequency information (e.g., cellReselectionServingFreqInfo). In the case of LTE, the SIB2 includes connection barring information, cell-common radio resource configuration information (radioResourceConfigCommon), and uplink carrier information. The cell-common radio resource configuration information includes configuration information about a cell-common Physical Random Access Channel (PRACH) and a Random Access Channel (RACH).

[0207] When the terminal device 40 fails to acquire the system information necessary for link establishment, the terminal device 40 determines that access to the cell is prohibited. For example, when acquisition of the first system information fails, the terminal device 40 determines that access to the cell is prohibited. In this case, the terminal device 40 ends the initial connection processing.

[0208] When the system information is successfully acquired, the terminal device 40 performs a random access procedure based on the first system information and / or the second system information (steps S14 to S17). The random access procedure can be referred to as a random access channel procedure (RACH procedure) or RA procedure.

[0209] The random access procedure includes steps of transmitting a random access preamble (step S14), receiving a random access response (step S15), transmitting a message 3 (step S16), and receiving a contention resolution (step S17).

[0210] First, the terminal device 40 selects a predetermined physical random access channel (PRACH) preamble, and transmits the selected preamble to the base station 20 (step S14). Next, the terminal device 40 receives a physical downlink shared channel (PDSCH) including a random access response corresponding to the PRACH preamble (step S15). Next, the terminal device 40 transmits a PUSCH including a message 3 using a resource scheduled by a random access response grant included in the random access response (step S16). Finally, the terminal device 40 receives a PDSCH containing a contention resolution corresponding to the PUSCH (step S17).

[0211] The message 3 includes a radio resource control (RRC) message of an RRC connection request. The contention resolution includes an RRC message for RRC connection setup. Upon receiving the RRC message of the RRC connection setup, the 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, the terminal device 40 transmits an RRC message indicating completion of the RRC connection setup to the base station 20. This series of operations allows the terminal device 40 to connect to the base station 20.

[0212] The random access preamble can be referred to as a message 1, the random access response can be referred to as a message 2, the contention resolution can be referred to as a message 4, and the RRC connection setup completion message can be referred to as a message 5.

[0213] After all steps of the random access procedure are completed, the terminal device 40 can transition to a state connected to the cell (connected state).

[0214] Note that, Figure 11The random access procedure in the above-described case 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, together with the random access preamble, also a message 3, and the base station 20 transmits, as a response to the received message, a random access response and a contention resolution can be referred to as a 2-step random access procedure (2-step RACH procedure).

[0215] <3-2. Random Access Procedure>

[0216] Next, the random access procedure will be described in detail.

[0217] The random access procedure is performed for the purpose of "RRC connection setup" from the idle state to the connected state (or inactive state), "state transition request" from the inactive state to the connected state, and the like. The random access procedure is also used for the purpose of "scheduling request" for resource request for uplink data transmission and "timing advance adjustment" for adjustment of uplink synchronization. Furthermore, the random access procedure is also performed in the case of, for example, "on-demand SI request" for requesting system information that has not been transmitted, "beam recovery" for recovering a broken beam connection, and "handover" for switching a connected cell.

[0218] "RRC connection setup" is an operation performed in association with generation of traffic or the like when the terminal device 40 is connected to the base station 20. Specifically, the operation is an operation of transferring information on connection (for example, UE context) from the base station 20 to the terminal device 40. The UE context is managed by predetermined communication device identification information (for example, C-RNTI) indicated from the base station 20. When this operation is completed, the terminal device 40 performs state transition from the idle state to the inactive state or from the idle state to the connected state.

[0219] "State transition request" is an operation in which the terminal device 40 requests state transition from the inactive state to the connected state in association with generation of traffic or the like. After transition to the connected state, the terminal device 40 can transmit and receive unicast data to and from the base station 20.

[0220] "Scheduling request" is an operation in which the terminal device 40 makes a resource request for uplink data transmission in association with generation of traffic or the like. After normally receiving the scheduling request, the base station 20 assigns resources of the PUSCH to the communication device. The scheduling request is also performed by the PUCCH.

[0221] "Timing advance adjustment" is an operation for adjusting an error between a downlink frame and an uplink frame caused by a propagation delay. The terminal device 40 transmits a physical random access channel (PRACH) to the downlink frame at an adjusted timing. This allows the base station 20 to identify the propagation delay to the terminal device 40 and indicate a value of the timing advance to the terminal device 40 through a message 2 or the like.

[0222] "SI request on demand" is an operation in which, when the terminal device 40 needs system information that is not transmitted for the purpose of overhead of the system information or the like, the base station 20 is requested to transmit the system information.

[0223] "Beam recovery" is an operation in which, when the communication quality is degraded due to movement of the terminal device 40 or another object interrupting a communication path after beam establishment, recovery is requested. Upon receipt of this request, the base station 20 attempts to connect to the terminal device 40 using a different beam.

[0224] "Handover" is an operation in which, due to a change in a radio wave environment, such as movement of the terminal device 40, a connection is switched from a cell (a serving cell) to which the terminal device 40 is connected to a cell (a neighbor cell) adjacent to the serving cell. Upon receipt of a handover command from the base station 20, the terminal device 40 makes a connection request to the neighbor cell designated by the handover command.

[0225] The random access procedure includes a contention-based random access procedure and a non-contention-based random access procedure.

[0226] The random access procedure described below is a random access procedure assuming that the RAT supported by the communication system 1 is LTE. However, the random access procedure described below is also applicable in the case where the RAT supported by the communication system 1 is a technology other than LTE.

[0227] <3-2-1. Contention-based random access procedure>

[0228] First, the contention-based random access procedure will be described. The contention-based random access procedure is a random access procedure that is executed at the initiative of the terminal device 40. Figure 12 is a diagram illustrating the contention-based random access procedure. As Figure 12 indicated in the diagram, the contention-based random access procedure is a 4-step procedure starting with transmission of a random access preamble from the terminal device 40. The contention-based random access procedure includes steps of transmitting a random access preamble (message 1), receiving a random access response (message 2), transmitting a message (message 3), and receiving a message for contention resolution (message 4).

[0229] First, the terminal device 40 randomly selects a preamble sequence to be used from among a plurality of predetermined preamble sequences. Subsequently, the terminal device 40 transmits a message (message 1: random access preamble) including the selected preamble sequence to the base station 20 as a connection destination (step S21). The random access preamble is transmitted on the PRACH.

[0230] Upon receiving the random access preamble, the base station 20 transmits a random access response (message 2) as a reply to the random access preamble to the terminal device 40. This random access response is transmitted using the PDSCH, for example. The terminal device 40 receives the random access response (message 2) transmitted from the base station 20 (step S22). The random access response includes one or a plurality of random access preambles that were successfully received by the base station 20 and uplink (UL) resources (hereinafter, referred to as uplink grant) corresponding to the random access preambles. The random access response includes a temporary cell radio network temporary identifier (TC-RNTI), which is an identifier unique to the terminal device 40 that is temporarily assigned to the terminal device 40 by the base station 20.

[0231] Upon receiving the random access response from the base station 20, the terminal device 40 discriminates whether the random access preamble transmitted in step S21 is included in the reception information. In the case where the random access preamble is included, the terminal device 40 extracts the uplink grant corresponding to the random access preamble transmitted in step S21 from among the uplink grants included in the random access response. Subsequently, the terminal device 40 transmits an UL message (message 3: scheduled transmission) using the resource scheduled by the extracted uplink grant (step S23). The transmission of the message (message 3) is performed using the PUSCH. The message (message 3) includes an RRC message for a radio resource control (RRC) connection request. The message (message 3) also includes an identifier of the terminal device 40. This message (message 3) can be denoted as "Msg3".

[0232] In the contention-based random access procedure, the random access preamble randomly selected by the terminal device 40 is used for the procedure. Therefore, a situation can occur in which another terminal device 40 also transmits the same random access preamble to the base station 20 at the same time as the terminal device 40 transmits the random access preamble. Therefore, by receiving the identifier transmitted by the terminal device 40 in step S23, the base station 20 identifies the position at which preamble contention has occurred between the terminal devices, to achieve contention resolution. The base station 20 transmits a contention resolution message (message 4) to the terminal device 40 selected for contention resolution. The contention resolution message (message 4) includes the identifier transmitted by the terminal device 40 in step S23. The contention resolution message (message 4) also includes an RRC message for RRC connection setup. The terminal device 40 receives the contention resolution message (message 4) transmitted from the base station 20 (step S24).

[0233] The terminal device 40 compares the identifier transmitted in step S23 with the identifier received in step S24. When the identifiers do not match, the terminal device 40 reattempts the random access procedure from step S21. When the identifiers match, the terminal device 40 performs an RRC connection operation, and transitions from the idle state (RRC_IDLE) to the connected state (RRC_CONNECTED). The terminal device 40 uses the TC-RNTI acquired in step S22 as a cell radio network temporary identifier (C-RNTI) in subsequent communication. After the transition to the connected state, the terminal device 40 transmits an RRC message indicating that the RRC connection setup is complete to the base station 20. The RRC connection setup complete message is also referred to as message 5. Through this series of operations, the terminal device 40 is connected to the base station 20.

[0234] Figure 12 The contention-based random access procedure illustrated in the figure is a 4-step random access procedure (4-step RACH). However, the communication system 1 can also support a 2-step random access procedure (2-step RACH) as a contention-based random access procedure. For example, the terminal device 40 also transmits the message (message 3) described in step S23 together with the transmission of the random access preamble. Subsequently, the base station 20 transmits a random access response (message 2) and contention resolution (message 4) in response. Since the random access procedure is completed in two steps, the terminal device 40 can be quickly connected to the base station 20.

[0235] <3-2-2. Non-contention-based random access procedure>

[0236] Next, a non-contention-based random access procedure will be described. The non-contention-based random access procedure is a random access procedure that is performed at the initiative of the base station. Figure 13is a diagram illustrating a non-contention-based random access procedure. The non-contention-based random access procedure is a 3-step procedure starting from the transmission of an assignment of a random access preamble from the base station 20. The non-contention-based random access procedure includes steps of receiving an assignment of a random access preamble (message 0), transmitting a random access preamble (message 1), and receiving a random access response (message 2).

[0237] In the contention-based random access procedure, the terminal device 40 randomly selects a preamble sequence. However, in the non-contention-based random access procedure, the base station 20 assigns an individual random access preamble to the terminal device 40. The terminal device 40 receives the random access preamble assignment (message 0: RA preamble assignment) from the base station 20 (step S31).

[0238] The terminal device 40 performs random access to the base station 20 by using the random access preamble assigned in step S31. That is, the terminal device 40 transmits the assigned random access preamble (message 1) to the base station 20 through the PRACH (step S32).

[0239] The base station 20 receives the random access preamble (message 1) from the terminal device 40. Subsequently, the base station 20 transmits a random access response (message 2) to the random access preamble to the terminal device 40 (step S33). The random access response, for example, includes information of an uplink grant corresponding to the received random access preamble. Upon receiving the random access response (message 2), the terminal device 40 performs an RRC connection operation, and transitions from the idle state (RRC_IDLE) to the connected state (RRC_CONNECTED).

[0240] In this way, the base station 20 schedules a random access preamble in the non-contention-based random access procedure, thereby suppressing the occurrence of preamble contention.

[0241] <3-3. Details of Random Access Procedure in NR>

[0242] The above describes the random access procedure assuming that the RAT supported by the communication system 1 is LTE. The random access procedure described above is also applicable to RATs other than LTE. Hereinafter, the random access procedure assuming that the RAT supported by the communication system 1 is NR will be described in detail. Hereinafter, the four steps of message 1 to message 4 shown in Figure 12 or Figure 13 will be specifically described. The step of message 1 corresponds to step S21 shown in Figure 12 and step S32 shown in Figure 13 . The step of message 2 corresponds to step S22 shown in Figure 12 and step S33 shown in Figure 13 . The step of message 3 corresponds toFigure 12 The step of message 4 corresponds to the step S23 shown in Figure 12 The step of message 4 corresponds to the step S23 shown in

[0243] NR random access preamble (message 1)

[0244] In NR, the PRACH is referred to as NR physical random access channel (NR-PRACH). The NR-PRACH is configured using a Zadoff-Chu sequence. In NR, a plurality of preamble formats are specified as formats of the NR-PRACH. The preamble format is specified by a combination of parameters of the PRACH, such as subcarrier spacing, transmission bandwidth, sequence length, number of symbols for transmission, number of transmission repetitions, cyclic prefix (CP) length, and guard period. The preamble sequence types of the NR-PRACH are numbered. The number of the preamble sequence type is expressed as a preamble index.

[0245] In NR, the settings regarding the NR-PRACH are performed on the terminal device 40 in the idle state through system information. Further, the settings regarding the NR-PRACH are performed on the terminal device 40 in the connected state through dedicated RRC signaling.

[0246] The terminal device 40 transmits the NR-PRACH using a physical resource (NR-PRACH occasion) that can be transmitted by the NR-PRACH. The physical resource is indicated by the settings regarding the NR-PRACH. The terminal device 40 selects one of the physical resources to transmit the NR-PRACH. Further, when the terminal device 40 is in the connected state, the terminal device 40 transmits the NR-PRACH using an NR-PRACH resource. The NR-PRACH resource is a combination of an NR-PRACH preamble and its physical resource. The base station 20 can indicate the NR-PRACH resource to the terminal device 40.

[0247] Note that the NR-PRACH is transmitted even when the random access procedure fails. At the time of retransmission of the NR-PRACH, the terminal device 40 suspends the transmission of the NR-PRACH for a suspension period, which is calculated from a backoff value (backoff indicator, BI). The backoff value can differ depending on the terminal category of the terminal device 40 and the priority of the generated traffic. At this time, the notification of the backoff value is provided a plurality of times, and the terminal device 40 selects the backoff value to be used from among them according to the priority. Further, when the NR-PRACH is retransmitted, the terminal device 40 increases the transmission power of the NR-PRACH compared to the initial transmission. This procedure is referred to as power ramping.

[0248] NR random access response (message 2)

[0249] 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 a cyclic redundancy check (CRC) has been scrambled using the RA-RNTI. The NR-PDCCH is transmitted on a Control Resource Set (CORESET). NR-PDCCHs with CRC scrambled by the RA-RNTI are placed in the Common Search Space (CSS) of the Type 1-PDCCH CSS set. The value of the 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. Transmission resources for the NR-PRACH include, 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 for placing the NR-PDCCH is set in association with the NR-PRACH preamble and / or the physical resources used for NR-PRACH transmission. The search space for placing the NR-PDCCH 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 QCL (quasi-common bit).

[0250] The NR random access response is Medium Access Control (MAC) information. The NR random access response includes at least uplink permission for sending 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 NR-PRACH transmission corresponding to the random access response. Furthermore, the NR random access response includes backoff information for pausing PRACH transmission.

[0251] Base station 20 sends 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. If the transmission of the random access preamble is successful, terminal device 40 executes the transmission processing of NR message 3 according to the information included in the random access response. Conversely, if the transmission of the random access preamble fails, terminal device 40 determines that the random access process has failed and executes NR-PRACH retransmission processing.

[0252] The NR random access response can include a plurality of uplink grants for transmitting the NR message 3. The terminal device 40 can select one resource from among the plurality of uplink grants for transmitting the message 3. This makes it possible to mitigate collision of the NR message 3 transmission in a case where different terminal devices 40 have received the same NR random access response. As a result, the communication system 1 can provide a more stable random access procedure.

[0253] NR message 3

[0254] The NR message 3 is transmitted by the NR physical uplink shared channel (NR-PUSCH). The NR-PUSCH is transmitted by using a resource indicated by the random access response. The NR message 3 includes an RRC connection request message. The format of the NR-PUSCH is indicated by a parameter included in the system information. For example, the parameter determines which NR-PUSCH format to use: orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-s-OFDM).

[0255] When the NR message 3 is normally received, the base station 20 proceeds with the transmission process of the contention resolution (message 4). In contrast, when the NR message 3 is not normally received, the base station 20 reattempts to receive the NR message 3 at least in a predetermined period.

[0256] Another example of the instruction and the transmission resource for the retransmission of the message 3 includes an instruction for indicating the NR-PDCCH for retransmitting the message 3. The NR-PDCCH is an uplink grant. The downlink control information (DCI) of the NR-PDCCH indicates a resource for the retransmission of the message 3. The terminal device 40 retransmits the message 3 based on the indication of the uplink grant.

[0257] When the NR contention resolution is not successfully received within a predetermined period, the terminal device 40 considers that the random access procedure has failed, and performs the NR-PRACH retransmission process. The transmission beam of the terminal device 40 for the retransmission of the NR message 3 can be different from the transmission beam of the terminal device 40 for the initial transmission of the message 3. In a case where neither the NR contention resolution indication nor the message 3 retransmission indication is received within a predetermined period, the terminal device 40 considers that the random access procedure has failed, and performs the NR-PRACH retransmission process. The predetermined period is set by the system information, for example.

[0258] NR contention resolution (message 4)

[0259] The NR contention resolution is transmitted using an NR-PDSCH. The NR-PDSCH containing the contention resolution is scheduled by an NR-PDCCH, where the CRC is scrambled by a TC-RNTI or a C-RNTI. The NR-PDCCH with the CRC scrambled by the TC-RNTI is placed in a CSS of a 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 another CSS.

[0260] When the NR-PDSCH containing the contention resolution is normally received, the terminal device 40 transmits an acknowledgement (ACK) response to the base station 20. Thereafter, the terminal device 40 considers that the random access procedure is successful, and enters into a connected state (RRC_CONNECTED). In contrast, when a negative acknowledgement (NACK) for the NR-PDSCH is received from the terminal device 40 or when there is no response, the base station 20 retransmits the NR-PDSCH containing the contention resolution. When the NR contention resolution (message 4) is not received within a predetermined period, the terminal device 40 considers that the random access procedure has failed, and performs a retransmission process of the random access preamble (message 1).

[0261] <3-4. 2-step RACH in NR>

[0262] Next, an example of a 2-step RACH procedure (hereinafter referred to as a 2-step random access procedure) in NR will be described. Figure 14 is a diagram illustrating a 2-step random access procedure. The 2-step random access procedure includes two steps of a message A (step S41) and a message B (step S42). As an example, the message A includes a message 1 (preamble) and a message 3 of a conventional 4-step random access procedure (4-step RACH procedure), and the message B includes a message 2 and a message 4 of the conventional 4-step random access procedure. Further, as an example, the message A includes a preamble (also referred to as a PRACH) and a PUSCH, and the message B includes a PDSCH.

[0263] By employing the 2-step random access procedure, the random access procedure can be completed with a lower latency compared to the conventional 4-step random access procedure.

[0264] The preamble and the PUSCH included in the message A can be set in association with each transmission resource, or can be set by independent resources.

[0265] When the individual transmission resources are set in association with each other, in a case where the transmission resource of the preamble is determined, for example, the PUSCH transmission resource is determined as the only resource, or a plurality of candidate transmission resources are determined. As an example, the time and frequency offset between the preamble of the PRACH occasion and the preamble of the PUSCH occasion is defined by one value. As another example, the time and frequency offset between the preamble of the PRACH occasion and the preamble of the PUSCH occasion is set to different values for each preamble. The value of the offset can be determined by the specification, or can be semi-statically set by the base station 20. As an example, the value of the time and frequency offset is defined by a predetermined frequency, for example. For example, in an unlicensed band (for example, a 5 GHz band, band 45), the value of the time offset can be set to 0 or a value close to 0. With this setting, it is possible to omit the Listen Before Talk (LBT) before transmission of the PUSCH.

[0266] On the other hand, when the transmission resources are set as independent resources, the transmission resources of the preamble and the PUSCH can be determined separately in the specification, or the resources can be semi-statically set by the base station 20, or can be determined based on other information. Examples of the other information include slot format information (for example, a slot format indicator), Band Width Part (BWP) information, preamble transmission resource information, a slot index, and a resource block index. Furthermore, when set with individual resources, the notification of the association between the preamble constituting one message A and the PUSCH can be provided to the base station through the payload of the PUSCH or the UCI included in the PUSCH, or can be provided to the base station 20 by transmitting physical parameters (for example, a PUSCH scrambling sequence, a DMRS sequence and / or pattern, or a PUSCH transmission antenna port) of the PUSCH.

[0267] The method of setting the transmission resources of the preamble and the PUSCH can be switched between the case of being set by mutual association and the case of being set with independent resources. For example, it is allowed to adopt the case of being set with individual resources in a licensed band, and the case of being set by mutual association of the transmission resources in an unlicensed band.

[0268] <<4. Operation of the communication system>>

[0269] The basic operation of the communication system has been described above. Next, the operation of the communication system 1 of the present embodiment will be described in detail below.

[0270] The base station 20 in the following embodiment can not only be a terrestrial station (terrestrial base station), but also a non-terrestrial station (non-terrestrial base station) that operates as a communication device, such as a satellite station, a drone, a balloon, or an airplane.

[0271] In the present embodiment, resources indicate frequency, time, resource elements (including REG, CCE, CORESET), resource blocks, bandwidth parts, component carriers, symbols, sub-symbols, slots, mini-slots, sub-slots, subframes, frames, PRACH occasions, occasions, codes, multiple access physical resources, multiple access signatures, and subcarrier spacings (numerology), and the like.

[0272] In the present embodiment, the technique of locally forming a cell is referred to as point shaping, but the term is not limited thereto. Further, in the following description, a communicable area formed by point shaping is referred to as a point cell, but the term is not limited thereto.

[0273] <4-1. Outline of Point Cell Determining Means>

[0274] As described above, the base station 20 performs coordinated control of a plurality of antennas to concentrate power in a specific place, thereby achieving formation of a point cell. That is, the base station 20 can form a point cell by a point shaping function.

[0275] Here, point shaping can be characterized in that, when power is concentrated in a specific place, the initial phase is different between the transmission antenna elements. On the other hand, beam shaping can be characterized in that, when a beam is formed in a specific direction, the initial phase shift is the same between the transmission antenna elements.

[0276] A point cell is a communicable area provided to the terminal device 40 by point shaping. The term of a communicable area is not limited to a point cell.

[0277] The base station 20 and / or the terminal device 40 perform a process for determining a point cell to which the terminal device 40 belongs. The point cell determining means can be one of the following (M1) to (M3). Of course, the point cell determining means can be a means other than (M1) to (M3).

[0278] (M1) Point Cell Determining Means Based on Power of Synchronization Signal

[0279] (M2) Point Cell Determining Means Based on Position Information

[0280] (M3) Point Cell Determining Means Based on Anchor Cell

[0281] The terminal device 40 performs initial access based on one of the above (M1) to (M3). Which of the above means (M1) to (M3) is to be used by the base station 20 and / or the terminal device 40 to determine a point cell can be determined by an administrator (for example, a network operator) of the communication system 1.

[0282] Hereinafter, an outline of the above (M1) to (M3) will be described.

[0283] (M1) Point cell determination means based on power of synchronization signal

[0284] A point cell to which the terminal device 40 belongs can be determined based on a synchronization signal transmitted by the base station 20 (e.g., power of the synchronization signal). For example, a point cell to which the terminal device 40 belongs can be determined based on power of a synchronization signal transmitted by the base station 20. The point cell determination means based on the synchronization signal can be the following Type 1 or Type 2. Of course, the point cell determination means by the synchronization signal can be means other than Type 1 and Type 2.

[0285] (1) Type 1

[0286] Figure 15 is a diagram for illustrating an example of the point cell determination means based on the power of the synchronization signal. The base station 20 forms a plurality of point cells PC covering predetermined areas. The base station 20 performs processing for determining a point cell PC to which the terminal device 40 belongs. For example, the base station 20 transmits a plurality of synchronization signals for the terminal device 40 to identify the point cell PC to the terminal device 40. Subsequently, the terminal device 40 determines a point cell PC to be connected based on the received synchronization signal. For example, the terminal device 40 pre-stores information for associating predetermined information (e.g., at least one of a sequence, a frequency resource, and a time resource) about the synchronization signal with a point cell ID. Subsequently, the terminal device 40 specifies a point cell PC to be connected based on the pre-stored information and the received synchronization signal. After the point cell PC is specified, the terminal device 40 connects to the specified point cell PC.

[0287] (2) Type 2

[0288] Figure 16 is a diagram for illustrating another example of the point cell determination means based on the power of the synchronization signal. The base station 20 can form a wide cell WC, which is a cell having a wider area than the point cell PC. When the wide cell WC is formed by a point forming function, the wide cell WC can also be referred to as a wide point cell. In this case, the point cell PC can also be referred to as a small point cell. The wide cell WC is not limited to a cell formed by a point forming function. For example, the wide cell WC can be a conventional communication cell (a classic cell) or a cell formed by a beam forming function. These terms of the cell are not limited to the wide cell / wide point cell or the point cell / small point cell.

[0289] The base station 20 forms one or more wide cells WC covering a predetermined area and a plurality of point cells PC covering the wide cells WC. The terminal device 40 selects a wide cell WC to be connected. Subsequently, the terminal device 40 connects (for example, attaches) to the base station 20. After the terminal device 40 connects to the wide cell WC, the base station 20 transmits a plurality of synchronization signals to the terminal device 40 so that the terminal device 40 identifies a point cell PC included in the wide cell WC to which the terminal device 40 belongs. Subsequently, the terminal device 40 determines a point cell PC to be connected based on the received synchronization signals. For example, the terminal device 40 pre-stores information for associating predetermined information (for example, at least one of a sequence, a frequency resource, and a time resource) on the synchronization signals with a point cell ID. Subsequently, the terminal device 40 specifies a point cell PC to be connected based on the pre-stored information and the received synchronization signals. After the point cell PC is specified, the terminal device 40 connects to the specified point cell PC.

[0290] (M2) Point cell determination means based on position information

[0291] The base station 20 can form a cell different from the point cell PC. For example, the base station 20 can form a wide cell WC, which is a cell having a wider area than the point cell PC. The terminal device 40 selects a cell (for example, a wide cell WC) to be connected. Subsequently, the terminal device 40 connects to the base station 20. During or after the connection, the base station 20 acquires position information of the terminal device 40. At this time, the base station 20 can acquire the position information from the terminal device 40. In addition, the base station 20 can measure the position of the terminal device 40 and acquire the measurement information as the position information of the terminal device 40. Subsequently, based on the position information of the terminal device 40, the base station 20 determines a point cell to which the terminal device 40 belongs.

[0292] With this means (point cell determination means based on position information), the base station 20 can determine an appropriate point cell based on the position information of the terminal device 40. Therefore, it is not necessary to perform the association between the synchronization signals and the point cells described in the point cell determination means based on the power of the synchronization signals described above.

[0293] (M3) Point cell determination means based on anchor cell

[0294] When connecting to a point cell, the terminal device 40 can connect to a conventional base station (another base station) that does not perform point shaping. For example, in a case where there is a cell serving as an anchor formed by a conventional base station, the terminal device 40 can connect to the cell serving as an anchor. After the connection, the base station 20 and / or the terminal device 40 can determine a point cell to which the terminal device 40 belongs based on information from another base station 20. For example, the terminal device 40 can determine a point cell to which the terminal device 40 belongs by communication in the cell serving as an anchor.

[0295] <4-2. Details of the Point Cell Determining Means>

[0296] The outline of the point cell determining means is described above. Hereinafter, the point cell determining means will be described in detail.

[0297] <4-2-1. Point Cell Determining Means Based on Synchronization Signal>

[0298] First, the point cell determining means based on synchronization signal will be described in detail.

[0299] For example, the point 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 point 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 point cell determining means based on synchronization signal can be Type 1 or Type 2. Hereinafter, Type 1 and Type 2 will be described in detail.

[0300] (1) Type 1

[0301] The base station 20 forms a plurality of point cells (for example, point cells PC shown in FIG. 6) covering the entire area of a predetermined area (for example, a point-shaped support area) in advance. Subsequently, the base station 20 transmits a plurality of synchronization signals for the terminal device 40 to identify the point cells to the terminal device 40. Subsequently, the terminal device 40 determines the point cell to be attached based on the received synchronization signals. Figure 15

[0302] In the present embodiment example, the base station 20 forms point cells in the entire area of a predetermined area in advance. The terminal device 40 receives a synchronization signal of the point cell to which the terminal device 40 belongs. Subsequently, the terminal device 40 transmits message 1 of the initial access procedure (random access procedure) using resources corresponding to the synchronization signal.

[0303] Upon receiving the message, the base station 20 can judge the point cell to which the terminal device 40 belongs depending on which point cell received message 1 of the initial access procedure (random access procedure).

[0304] The base station 20 can simultaneously transmit a plurality of synchronization signals. For example, with respect to the transmission of synchronization signals of a plurality of point cells covering a predetermined area, the base station 20 can simultaneously transmit a plurality of synchronization signals. When the synchronization signals are simultaneously transmitted, the transmission power is distributed by the number of point cells, resulting in the possibility of a decrease in reception quality in the point cells. However, the synchronization signals are simultaneously transmitted, maximizing the spatial multiplexing efficiency.

[0305] ​The base station 20 can transmit a plurality of synchronization signals at different times in a dispersed manner. In the case where the synchronization signals are transmitted at different times in a dispersed manner, there is a time in each point cell where communication cannot be performed. This results in a possibility of a decrease in spatial multiplexing efficiency compared to the case where the synchronization signals are transmitted at the same time. However, since the synchronization signals are transmitted at different times in a dispersed manner, the reception quality in the point cell is improved.

[0306] (2) Type 2

[0307] The base station 20 forms one or more wide point cells (for example, a wide cell WC shown in FIG. 1) covering a predetermined area in advance, and the terminal device 40 selects a wide point cell to be attached. After attachment to the wide point cell, the base station 20 and / or the terminal device 40 performs a process of selecting an appropriate small point cell among small point cells (for example, point cells PC shown in FIG. 1) belonging to the selected wide point cell. Figure 16 The base station 20 forms one or more wide point cells (for example, a wide cell WC shown in FIG. 1) covering a predetermined area in advance, and the terminal device 40 selects a wide point cell to be attached. After attachment to the wide point cell, the base station 20 and / or the terminal device 40 performs a process of selecting an appropriate small point cell among small point cells (for example, point cells PC shown in FIG. 1) belonging to the selected wide point cell. Figure 16 The base station 20 forms one or more wide point cells (for example, a wide cell WC shown in FIG. 1) covering a predetermined area in advance, and the terminal device 40 selects a wide point cell to be attached. After attachment to the wide point cell, the base station 20 and / or the terminal device 40 performs a process of selecting an appropriate small point cell among small point cells (for example, point cells PC shown in FIG. 1) belonging to the selected wide point cell.

[0308] In the following description, a wide cell (for example, a wide cell WC shown in FIG. 1) is referred to as a wide point cell, and a point cell (for example, a point cell PC shown in FIG. 1) is referred to as a small point cell. The wide point cell in the following description can be changed to a wide cell, and the small point cell can be changed to a point cell. Figure 16 Figure 16 The base station 20 forms one or more wide point cells (for example, a wide cell WC shown in FIG. 1) covering a predetermined area in advance, and the terminal device 40 selects a wide point cell to be attached. After attachment to the wide point cell, the base station 20 and / or the terminal device 40 performs a process of selecting an appropriate small point cell among small point cells (for example, point cells PC shown in FIG. 1) belonging to the selected wide point cell.

[0309] The base station 20 forms one or more wide point cells (for example, a wide cell WC shown in FIG. 1) covering a predetermined area in advance, and the terminal device 40 selects a wide point cell to be attached. After attachment to the wide point cell, the base station 20 and / or the terminal device 40 performs a process of selecting an appropriate small point cell among small point cells (for example, point cells PC shown in FIG. 1) belonging to the selected wide point cell.

[0310] Upon receipt of the message, the base station 20 can determine the wide point cell to which the terminal device 40 belongs depending on which wide point cell received the message 1 of the initial access process (random access process).

[0311] The base station 20 can transmit a plurality of synchronization signals at the same time. For example, with respect to transmission of synchronization signals for a plurality of wide point cells covering a predetermined area, the base station 20 can transmit a plurality of synchronization signals at the same time. When the synchronization signals are transmitted at the same time, the transmission power is distributed by the number of wide point cells, resulting in a possibility of a decrease in reception quality in the wide point cell. However, since the synchronization signals are transmitted at the same time, the spatial multiplexing efficiency is maximized.

[0312] ​The base station 20 can transmit a plurality of synchronization signals at different times in a dispersed manner. In the case where the synchronization signals are transmitted at different times in a dispersed manner, there is a time in each of the pico cells where communication cannot be performed. This can result in a possibility of a decrease in spatial multiplexing efficiency compared to the case where the synchronization signals are transmitted at the same time. However, when the synchronization signals are transmitted at different times in a dispersed manner, the reception quality in the pico cells is improved.

[0313] After performing the initial access, the base station 20 and the terminal device 40 perform communication in the wide pico cell to which the terminal device 40 belongs.

[0314] After the terminal device 40 is connected to the wide pico cell, the base station 20 can transmit a plurality of synchronization signals to the terminal device 40 so that the terminal device 40 identifies the small pico cells included in the wide pico cell to which the terminal device 40 belongs. Subsequently, the terminal device 40 can determine the small pico cell to be connected based on the received synchronization signals.

[0315] After the terminal device 40 starts communication in the wide pico cell, the base station 20 can perform processing for changing the cell to which the terminal device 40 is connected from the wide pico cell to a small pico cell. For example, the base station 20 can transmit a plurality of different reference signals associated with a plurality of small pico cells to the terminal device 40. For example, the terminal device 40 can measure the reception quality of the received reference signals and provide the result as feedback to the base station 20. Based on the feedback information from the terminal device 40, the base station 20 that received the feedback can determine the pico cell to which the terminal device 40 belongs.

[0316] Subsequently, the terminal device 40 can perform random access with the small pico cell determined by the base station 20. At this stage, the terminal device 40 has completed connection with the wide pico cell. Therefore, the base station 20 can transmit only the synchronization signals of the small pico cells belonging to the area of the wide pico cell. At this time, the synchronization signals of the small pico cells and the small pico cell IDs can be associated with each other. Subsequently, the terminal device 40 can identify the small pico cell ID to be connected based on the synchronization signals.

[0317] The base station 20 and the terminal device 40 can be configured to be able to combine a plurality of frequency bands by carrier aggregation or dual connectivity. The base station 20 and the terminal device 40 can perform communication using at least one of the plurality of frequency bands as a frequency band that provides a pico cell.

[0318] For example, the base station 20 and the terminal device 40 can apply the wide pico cell and the small pico cell in combination with a mechanism such as carrier aggregation or dual connectivity. For example, the base station 20 and the terminal device 40 can perform communication using at least one of the plurality of frequency bands as a frequency band that provides a wide pico cell and using at least another frequency band as a frequency band that provides a small pico cell.

[0319] For example, the base station 20 and the terminal device 40 can set the frequency band A used in the carrier aggregation to a frequency band that provides a wide spot cell, and set the frequency band B used in the carrier aggregation to a frequency band that provides a small spot cell. Further, the base station 20 and the terminal device 40 can set the frequency band A used in the dual connectivity to a frequency band that provides a wide spot cell, and set the frequency band B used in the dual connectivity to a frequency band that provides a small spot cell. Further, the terminal device 40 can set the base station A used in the dual connectivity to a frequency band that provides a wide spot cell, and set the base station B used in the dual connectivity to a frequency band that provides a small spot cell.

[0320] <4-2-2. Spot cell determination means based on position information>

[0321] Next, the spot cell determination means based on position information will be described in detail.

[0322] The base station 20 forms one or more cells that cover a predetermined area in advance. At this time, the cell formed by the base station 20 can be a cell different from a spot cell (a small spot cell). For example, the cell formed by the base station 20 can be a wide cell. Subsequently, the terminal device 40 selects a cell to be attached, and attaches the cell. During or after the attachment, the base station 20 acquires position information of the terminal device 40. At this time, the base station 20 can acquire the position information from the terminal device 40. Further, the base station 20 can measure the position of the terminal device 40, and acquire the measurement information as the position information of the terminal device 40. Subsequently, based on the position information of the terminal device 40, the base station 20 determines a spot cell to which the terminal device 40 belongs.

[0323] The base station 20 forms one or more cells (for example, a wide cell) in a predetermined area (for example, a spot formation support area) in advance. Subsequently, the base station 20 transmits a plurality of synchronization signals to the terminal device 40 so that the terminal device 40 recognizes the cells. The terminal device 40 receives a synchronization signal of a cell to which the terminal device 40 belongs. Subsequently, the terminal device 40 transmits a message 1 of an initial access procedure (a random access procedure) using a resource corresponding to the synchronization signal.

[0324] Upon receiving the message, the base station 20 can determine a cell to which the terminal device 40 belongs depending on which cell received the message 1 of the initial access procedure (the random access procedure).

[0325] During or after the execution of the initial access, the base station 20 acquires position information of the terminal device 40.

[0326] At this time, the base station 20 can acquire the position information of the terminal device 40 from the terminal device 40. For example, the terminal device 40 can measure the position of the terminal device 40 based on information such as a position measuring device included in the terminal device 40. The terminal device 40 can notify the base station 20 of the measured position. The base station 20 can acquire the information notified from the terminal device 40 as the position information of the terminal device 40.

[0327] Further, the base station 20 can measure the position of the terminal device 40. Subsequently, the base station 20 can acquire the measurement information as the position information of the terminal device 40. At this time, the base station 20 can transmit a reference signal (for example, a positioning reference signal) for position measurement to the terminal device 40, and the terminal device 40 can transmit the measurement result as feedback to the base station 20.

[0328] Note that the base station 20 can acquire the position information of the terminal device 40 using a zone ID and the like used in Vehicle to X (V2X).

[0329] Subsequently, the base station 20 can determine the point cell (small point cell) to which the terminal device 40 belongs based on the position information of the terminal device 40. The base station 20 can notify the terminal device 40 of information necessary for communication in the point cell.

[0330] Subsequently, the terminal device 40 performs communication in the point cell to which the terminal device 40 belongs.

[0331] <4-2-3. Point cell determination means based on anchor cell>

[0332] Next, the point cell determination means based on the anchor cell will be described in detail.

[0333] Upon connection to the point cell, the terminal device 40 can attach to a cell serving as an anchor formed by a conventional base station (another base station) that does not perform point shaping. After attachment, the base station 20 and / or the terminal device 40 can determine the point cell to which the terminal device 40 belongs based on information from the other base station 20.

[0334] In the present embodiment example, the terminal device 40 receives a synchronization signal of an anchor cell formed by a conventional base station. Subsequently, with a resource corresponding to the synchronization signal, the terminal device 40 transmits message 1 of an initial access procedure (random access procedure).

[0335] Upon reception of the message, the base station 20 can judge the anchor cell to which the terminal device 40 belongs depending on which cell received message 1 of the initial access procedure (random access procedure).

[0336] After performing the initial access, the base station 20 and the terminal device 40 perform communication in the anchor cell.

[0337] After starting communication, the base station 20 can perform processing for adding a point cell (small point cell) (hereinafter, referred to as "point cell addition processing"). The point cell addition processing can be one of the following (1) to (3).

[0338] (1) Point cell addition processing based on power measurement

[0339] For example, the base station 20 can notify the terminal device 40 of information necessary for communication with the point cell through communication in the anchor cell.

[0340] Further, the base station 20 can transmit a plurality of different reference signals associated with the point cell to the terminal device 40. At this time, the terminal device 40 can measure reception quality of the received reference signals, and provide the result as feedback to the base station 20. Based on the feedback information from the terminal device 40, the base station 20 that has received the feedback can determine the point cell to which the terminal device 40 belongs. Subsequently, the terminal device 40 can start communication with the determined point cell.

[0341] Further, the terminal device 40 can perform random access with the point cell using random access information on the point cell.

[0342] (2) Point cell addition processing based on position information

[0343] During or after performing initial access, the base station 20 can acquire position information of the terminal device 40.

[0344] At this time, the base station 20 can acquire the position information from the terminal device 40. For example, the terminal device 40 can measure the position of the terminal device 40 based on information such as a position measuring device included in the terminal device 40. The terminal device 40 can notify the base station 20 of the measured position. The base station 20 can acquire the information notified from the terminal device 40 as the position information of the terminal device 40.

[0345] Further, the base station 20 can measure the position of the terminal device 40. Subsequently, the base station 20 can acquire the measurement information as the position information of the terminal device 40. At this time, the base station 20 can transmit a reference signal for position measurement (for example, a positioning reference signal) to the terminal device 40, and the terminal device 40 can transmit the measurement result as feedback to the base station 20.

[0346] Subsequently, the base station 20 can determine the point cell (small point cell) to which the terminal device 40 belongs based on the position information of the terminal device 40. The base station 20 can notify the terminal device 40 of information necessary for communication in the point cell through communication in the anchor cell.

[0347] Subsequently, the terminal device 40 performs communication in the point cell to which the terminal device 40 belongs.

[0348] (3) Point cell addition processing based on information from another base station

[0349] The base station 20 can acquire information on the terminal device 40 from a conventional base station (another base station) that provides an anchor cell to the terminal device 40. Subsequently, the base station 20 can determine a point cell to which the terminal device 40 belongs, based on the information from the conventional base station (another base station).

[0350] Further, the conventional base station (another base station) that provides an anchor cell to the terminal device 40 can be configured to be able to determine a point cell to which the terminal device 40 belongs. The base station 20 can acquire determination information of a point cell to which the terminal device 40 belongs, from the conventional base station (another base station). Subsequently, the base station 20 can determine a point cell to which the terminal device 40 belongs, based on the determination information acquired from the conventional base station (another base station).

[0351] <4-2-4. Supplementary explanation>

[0352] The synchronization signal transmitted from the base station 20 can be one of the following (A1) to (A3).

[0353] (A1) Primary Synchronization Signal (PSS)

[0354] (A2) Secondary Synchronization signal (SSS)

[0355] (A3) Tertiary Synchronization signal (TSS)

[0356] The system information transmitted from the base station 20 can be transmitted by one of the following (B1) to (B2).

[0357] (B1) Physical Broadcast channel (PBCH)

[0358] (B2) Physical Downlink Shared channel (PDSCH)

[0359] As information necessary for determining a point cell, at least one of the following information (C1) to (C3) can be provided from the terminal device 40 to the base station 20.

[0360] (C1) Position measurement capability information

[0361] (C2) Position information of the terminal device

[0362] (C3) Channel information

[0363] For example, the terminal device 40 receives a reference signal transmitted from the base station 20, and measures a channel matrix between each antenna element and the terminal device 40. Subsequently, the terminal device 40 notifies the base station 20 of the measurement result as channel information. The terminal device 40 can notify the base station 20 of the unprocessed measurement result as channel information. Alternatively, the terminal device 40 can apply eigenvalue decomposition to the channel matrix to obtain an eigenvector, and notify the base station 20 of the eigenvector as channel information.

[0364] <<5. Sequence example>>

[0365] The operation of the communication system has been described above. Next, a sequence example of the initial access processing of the present embodiment will be described.

[0366] How the 4-step random access procedure (4-step RACH) and the 2-step random access procedure (2-step RACH) as initial access means are related to the determination of the pico cell will be described below.

[0367] As described above, the pico cell determination means can be one of the following (M1) to (M3).

[0368] (M1) Synchronization signal-based pico cell determination means

[0369] (M2) Position information-based pico cell determination means

[0370] (M3) Anchor cell-based pico cell determination means

[0371] Below, a sequence example will be described for each of (M1) to (M3).

[0372] <5-1. Synchronization signal-based pico cell determination means>

[0373] First, a sequence example of the initial access processing related to the synchronization signal-based pico cell determination means will be described. The synchronization signal-based pico cell determination means can be one of the following (M1-1) to (M1-4).

[0374] (M1-1) Means for determining a pico cell during a 4-step RACH processing

[0375] (M1-2) Means for determining a wide cell (wide pico cell) and a pico cell (small pico cell) during a 4-step RACH processing

[0376] (M1-3) Means for determining a pico cell during a 2-step RACH processing

[0377] (M1-4) Means for determining a wide cell (wide pico cell) and a pico cell (small pico cell) during a 2-step RACH processing

[0378] Hereinafter, an example sequence of initial access processing will be described for each of (M1-1) to (M1-4). The following processing is performed, for example, by the control unit 23 of the base station 20 (acquisition unit 231, forming unit 232, determination processing unit 233, connection processing unit 234 or measurement unit 235) and the control unit 43 of the terminal device 40 (determination processing unit 431 or communication control unit 432).

[0379] <5-1-1. Example of a sequence based on M1-1>

[0380] Figure 17 This is a diagram illustrating an example sequence of initial access procedures related to the means of determining the point cell during the 4-step RACH process. The following will refer to... Figure 17 Describe the initial access process according to this method.

[0381] Base station 20 sends synchronization signals and system information to terminal device 40 (step S101). At this time, the synchronization signals and / or system information may include information that can be used to identify each point cell.

[0382] Terminal device 40 receives synchronization signals and system information, and determines the point cell based on the received synchronization signals and system information (step S102).

[0383] Terminal device 40 sends the random access preamble to base station 20 (step S103). At this time, the random access preamble can be sent using a sequence of random access preambles corresponding to the point cell and / or transmission resource configuration.

[0384] Base station 20 sends a random access response to terminal device 40 (step S104).

[0385] Terminal device 40 sends message 3 information from random access to base station 20 (step S105). At this time, the location information of the terminal can be included in message 3 information.

[0386] Base station 20 sends the contention resolution information to terminal device 40 (step S106). Subsequently, base station 20 sends RRC signaling information to terminal device 40 (step S107).

[0387] <5-1-2. Example of a sequence based on M1-2>

[0388] Figure 18 This is a diagram illustrating an example sequence of initial access procedures related to the means of determining wide cells and point cells during the 4-step RACH process. In the following description, wide cell can be replaced with wide point cell, and point cell can be replaced with small point cell. The following will refer to... Figure 18 Describe the initial access process according to this method.

[0389] The base station 20 transmits a synchronization signal and system information of a wide cell (wide spot cell) to the terminal device 40 (step S201). At this time, the synchronization signal and / or the system information can include information that can be used to identify each wide cell (wide spot cell).

[0390] The terminal device 40 receives the synchronization signal and the system information, and determines a wide cell (wide spot cell) based on the received synchronization signal and the system information (step S202).

[0391] The terminal device 40 transmits a random access preamble to the base station 20 (step S203). At this time, the random access preamble can be transmitted with a sequence and / or a transmission resource configuration of the random access preamble corresponding to the wide cell (wide spot cell).

[0392] The base station 20 transmits a random access response to the terminal device 40 (step S204). Here, the terminal device 40 can be notified of information such as information on a transmission implementation of system information or a synchronization signal of a spot cell (small spot cell) and information on a transmission resource.

[0393] The base station 20 transmits a synchronization signal and system information of a spot cell (small spot cell) to the terminal device 40 (step S205). At this time, the synchronization signal and / or the system information can include information that can be used to identify each spot cell (small spot cell).

[0394] The terminal device 40 receives the synchronization signal and the system information, and determines a spot cell (small spot cell) based on the received synchronization signal and the system information (step S206).

[0395] The terminal device 40 transmits a random access preamble to the base station 20 (step S207). At this time, the random access preamble can be transmitted with a sequence and / or a transmission resource configuration of the random access preamble corresponding to the spot cell (small spot cell).

[0396] The base station 20 transmits a random access response to the terminal device 40 (step S208).

[0397] The terminal device 40 transmits message 3 information in random access to the base station 20 (step S209). At this time, position information of the terminal device 40 can be included in the message 3 information.

[0398] The base station 20 transmits a contention resolution to the terminal device 40 (step S210). Subsequently, the base station 20 transmits RRC signaling information to the terminal device 40 (step S211).

[0399] <5-1-3. Sequence example according to M1-3>

[0400] Figure 19is a diagram illustrating a sequence example of initial access processing related to a means of determining a point cell during 2-step RACH processing. Hereinafter, the description will be made with reference to Figure 19 An initial access processing according to the present means is described.

[0401] The base station 20 transmits a synchronization signal and system information to the terminal device 40 (step S301). At this time, the synchronization signal and / or the system information can include information usable to discriminate each point cell.

[0402] The terminal device 40 receives the synchronization signal and the system information, and determines a point cell based on the received synchronization signal and the system information (step S302).

[0403] The terminal device 40 transmits a random access preamble and message 3 information to the base station 20 (step S303). At this time, the random access preamble can be transmitted with a sequence of the random access preamble and / or a transmission resource configuration corresponding to the point cell. The message 3 information can include location information of the terminal device 40. This information can be referred to as a message A, or can be referred to as another term.

[0404] The base station 20 transmits a random access response and contention resolution to the terminal device 40 (step S304). This information can be referred to as a message B, or can be referred to as another term.

[0405] The base station 20 transmits RRC signaling information to the terminal device 40 (step S305).

[0406] <5-1-4. Sequence example according to M1-4>

[0407] Figure 20 is a diagram illustrating a sequence example of initial access processing related to a means of determining a wide cell and a point cell during 2-step RACH processing. The wide cell in the following description can be replaced with a wide point cell, and the point cell can be replaced with a small point cell. Hereinafter, the description will be made with reference to Figure 20 An initial access processing according to the present means is described.

[0408] The base station 20 transmits a synchronization signal and system information of a wide cell (wide point cell) to the terminal device 40 (step S401). At this time, the synchronization signal and / or the system information can include information usable to discriminate each wide cell (wide point cell).

[0409] The terminal device 40 receives the synchronization signal and the system information, and determines a wide cell (wide point cell) based on the received synchronization signal and the system information (step S402).

[0410] The terminal device 40 transmits a random access preamble and message 3 information to the base station 20 (step S403). At this time, the random access preamble can be transmitted with a sequence of the random access preamble and / or a transmission resource configuration corresponding to the wide cell (wide pico cell). The message 3 information can include location information of the terminal device 40. This information can be referred to as message A, or can be referred to as another term.

[0411] The base station 20 transmits a random access response and contention resolution to the terminal device 40 (step S404). This information can be referred to as message B, or can be referred to as another term. Here, the terminal device 40 can be notified of information on a transmission implementation of a synchronization signal or system information of the pico cell (small pico cell), information on a transmission resource, and the like.

[0412] The base station 20 transmits a synchronization signal and system information of the pico cell (small pico cell) to the terminal device 40 (step S405). At this time, the synchronization signal and / or the system information can include information that can be used to discriminate each pico cell (small pico cell).

[0413] The terminal device 40 receives the synchronization signal and the system information, and determines the pico cell (small pico cell) based on the received synchronization signal and the system information (step S406).

[0414] The terminal device 40 transmits a random access preamble and message 3 information to the base station 20 (step S407). At this time, the random access preamble can be transmitted with a sequence of the random access preamble and / or a transmission resource configuration corresponding to the pico cell (small pico cell). The message 3 information can include location information of the terminal device 40. This information can be referred to as message A, or can be referred to as another term.

[0415] The base station 20 transmits a random access response and contention resolution to the terminal device 40 (step S408). This information can be referred to as message B, or can be referred to as another term.

[0416] The base station 20 transmits RRC signaling information to the terminal device 40 (step S409).

[0417] <5-2. Pico Cell Determining Means Based on Location Information>

[0418] Next, a sequence example of the initial access processing related to the pico cell determining means based on location information will be described. The pico cell determining means based on location information can be one of the following (M2-1) to (M2-4).

[0419] (M2-1) Means of determining a pico cell during a 4-step RACH processing (in a case of transmitting an SRS during a random access preamble transmission to perform location measurement)

[0420] (M2-2) Means for determining a point cell during 4-step RACH processing (case where PRS is transmitted during random access response transmission to perform position measurement)

[0421] (M2-3) Means for determining a point cell during 4-step RACH processing (case where SRS is transmitted during message 3 transmission to perform position measurement)

[0422] (M2-4) Means for determining a point cell during 4-step RACH processing (case where PRS is transmitted after random access to perform position measurement)

[0423] (M2-5) Means for determining a point cell during 4-step RACH processing (case where SRS is transmitted after random access to perform position measurement)

[0424] (M2-6) Means for determining a point cell during 2-step RACH processing (case where SRS is transmitted during message A transmission to perform position measurement)

[0425] (M2-7) Means for determining a point cell during 2-step RACH processing (case where PRS is transmitted after random access to perform position measurement)

[0426] (M2-8) Means for determining a point cell during 2-step RACH processing (case where SRS is transmitted after random access to perform position measurement)

[0427] Hereinafter, a sequence example of the initial access processing will be described for each of (M2-1) to (M2-8). The following processing is, for example, performed by the control unit 23 (acquisition unit 231, formation unit 232, determination processing unit 233, connection processing unit 234, or measurement unit 235) of the base station 20 and the control unit 43 (determination processing unit 431 or communication control unit 432) of the terminal device 40.

[0428] <5-2-1. Sequence example according to M2-1>

[0429] Figure 21 is a diagram illustrating a sequence example of the initial access processing related to the means for determining a point cell during 4-step RACH processing. Here, the point cell determination means when performing position measurement by transmitting a sounding reference signal (SRS) at the time of transmitting a random access preamble will be described below. Hereinafter, the initial access processing according to the present means will be described with reference to Figure 21

[0430] ​The base station 20 transmits a synchronization signal and system information to the terminal device 40 (step S501). Here, in order to estimate the position of the terminal device 40, transmission of a sounding reference signal (SRS) can be requested by the system information or the like.

[0431] The terminal device 40 receives the synchronization signal and the system information. Subsequently, the terminal device 40 transmits a random access preamble to the base station 20 (step S502). At this time, the terminal device 40 transmits an SRS to the base station 20 together with the random access preamble.

[0432] The base station 20 determines a point cell using terminal position information measured from the received SRS (step S503). Subsequently, the base station 20 transmits a random access response to the terminal device 40 (step S504). Here, the base station 20 can notify the terminal device 40 of information of a point cell to be connected.

[0433] The terminal device 40 transmits message 3 information in random access to the base station 20 (step S505).

[0434] The base station 20 transmits a contention resolution to the terminal device 40 (step S506). Here, the base station 20 can notify the terminal device 40 of information of a point cell to be connected. Subsequently, the base station 20 transmits RRC signaling information to the terminal device 40 (step S507). Here, the base station 20 can notify the terminal device 40 of information of a point cell to be connected.

[0435] <5-2-2. Sequence example according to M2-2>

[0436] Figure 22 is a diagram illustrating a sequence example of an initial access process related to a means of determining a point cell during a 4-step RACH process. Here, a point cell determination means when performing position measurement by transmitting a positioning reference signal (PRS) at the time of transmitting a random access response will be described below. Hereinafter, reference will be made to Figure 22 An initial access process according to the present means will be described.

[0437] The base station 20 transmits a synchronization signal and system information to the terminal device 40 (step S601).

[0438] The terminal device 40 receives the synchronization signal and the system information. Subsequently, the terminal device 40 transmits a random access preamble to the base station 20 (step S602).

[0439] The base station 20 transmits a random access response to the terminal device 40 (step S603). Here, in order to perform position measurement in the terminal device 40, the base station 20 can also transmit a positioning reference signal (PRS) to the terminal device 40.

[0440] Terminal device 40 performs location measurement using the received PRS (step S604). Subsequently, terminal device 40 sends message 3 information from random access to base station 20 (step S605). Here, terminal device 40 can notify base station 20 of the location measurement result of terminal device 40 together with message 3.

[0441] Base station 20 uses the received terminal location information to determine the point cell (step S606). Subsequently, base station 20 sends the contention resolution to terminal device 40 (step S607). Here, base station 20 can notify terminal device 40 of the point cell to be connected.

[0442] Base station 20 sends RRC signaling information to terminal device 40 (step S608). Here, base station 20 can notify terminal device 40 of the information of the point cell to be connected.

[0443] <5-2-3. Example of a sequence based on M2-3>

[0444] Figure 23 This diagram illustrates an example sequence of initial access processing related to the means of determining the point cell during the 4-step RACH process. Here, the means of point cell determination when performing location measurement by transmitting a sounding reference signal (SRS) at message 3 will be described below. Referring to the following... Figure 23 Describe the initial access process according to this method.

[0445] Base station 20 sends synchronization signals and system information to terminal device 40 (step S701).

[0446] Terminal device 40 receives synchronization signals and system information. Subsequently, terminal device 40 sends a random access preamble to base station 20 (step S702).

[0447] Base station 20 sends a random access response to terminal device 40 (step S703). Here, in order to estimate the location of terminal device 40, a sounding reference signal (SRS) can be requested to be sent through the random access response or the like.

[0448] Terminal device 40 sends message 3 information from random access to base station 20 (step S704). At this time, terminal device 40 sends SRS together with message 3 to base station 20.

[0449] Base station 20 uses the terminal location information measured from the received SRS to determine the point cell (step S705). Subsequently, base station 20 sends the contention resolution to terminal device 40 (step S706). Here, base station 20 can notify terminal device 40 of the point cell to be connected.

[0450] The base station 20 transmits RRC signaling information to the terminal device 40 (step S707). Here, the base station 20 can notify the terminal device 40 of information of the point cell to be connected.

[0451] <5-2-4. Sequence example according to M2-4>

[0452] Figure 24 is a diagram illustrating a sequence example of an initial access process related to a means of determining a point cell during a 4-step RACH process. Here, the point cell determination means when performing position measurement by transmitting a positioning reference signal (PRS) after random access will be described below. Hereinafter, the initial access process according to the present means will be described with reference to Figure 24

[0453] The base station 20 transmits a synchronization signal and system information to the terminal device 40 (step S801).

[0454] The terminal device 40 receives the synchronization signal and system information. Subsequently, the terminal device 40 transmits a random access preamble to the base station 20 (step S802).

[0455] The base station 20 transmits a random access response to the terminal device 40 (step S803).

[0456] The terminal device 40 transmits message 3 information in the random access to the base station 20 (step S804).

[0457] The base station 20 transmits a contention resolution to the terminal device 40 (step S805). Subsequently, the base station 20 transmits RRC signaling information to the terminal device 40 (step S806). Here, in order to perform position measurement in the terminal device 40, the base station 20 also transmits a positioning reference signal (PRS) to the terminal device 40 (step S807).

[0458] The terminal device 40 performs position measurement of the terminal device 40 using the received PRS (step S808). Subsequently, the terminal device 40 notifies the base station 20 of the position measurement result of the terminal device 40 (step S809).

[0459] The base station 20 determines a point cell using the received terminal position information (step S810). Subsequently, the base station 20 notifies the terminal device 40 of information of the point cell to be connected (step S811).

[0460] <5-2-5. Sequence example according to M2-5>

[0461] Figure 25 ​is a diagram illustrating a sequence example of initial access processing related to the means of determining a point cell during 4-step RACH processing. Here, the point cell determination means when performing position measurement by transmitting a sounding reference signal (SRS) after random access will be described below. Hereinafter, the point cell determination means will be described with reference to Figure 25 The initial access processing according to the present means will be described.

[0462] The base station 20 transmits a synchronization signal and system information to the terminal device 40 (step S901).

[0463] The terminal device 40 receives the synchronization signal and system information. Subsequently, the terminal device 40 transmits a random access preamble to the base station 20 (step S902).

[0464] The base station 20 transmits a random access response to the terminal device 40 (step S903).

[0465] The terminal device 40 transmits message 3 information in random access to the base station 20 (step S904).

[0466] The base station 20 transmits a contention resolution to the terminal device 40 (step S905). Subsequently, the base station 20 transmits RRC signaling information to the terminal device 40 (step S906).

[0467] For position measurement, the terminal device 40 transmits a sounding reference signal (SRS) to the base station 20 (step S907).

[0468] The base station 20 measures the position of the terminal device 40 using the received SRS, and determines a point cell using terminal position information (step S908). Subsequently, the base station 20 notifies the terminal device 40 of information of a point cell to be connected (step S909).

[0469] <5-2-6. Sequence example according to M2-6>

[0470] Figure 26 is a diagram illustrating a sequence example of initial access processing related to the means of determining a point cell during 2-step RACH processing. Here, the point cell determination means when performing position measurement by transmitting a sounding reference signal (SRS) at the time of transmitting message A will be described below. Hereinafter, the point cell determination means will be described with reference to Figure 26 The initial access processing according to the present means will be described.

[0471] The base station 20 transmits a synchronization signal and system information to the terminal device 40 (step S1001). Here, in order to estimate the position of the terminal device 40, the base station 20 can request transmission of a sounding reference signal (SRS) by system information or the like.

[0472] The terminal device 40 receives the synchronization signal and the system information. Subsequently, the terminal device 40 transmits a random access preamble and message 3 information to the base station 20 (step S1002). Here, this information can be referred to as message A, or can be referred to as another term. At this time, the terminal device 40 transmits an SRS to the base station 20 together with the message A.

[0473] The base station 20 determines the point cell using the terminal position information measured from the received SRS (step S1003).

[0474] The base station 20 transmits a random access response and a contention resolution to the terminal device 40 (step S1004). This information can be referred to as message B, or can be referred to as another term. Here, the base station 20 can notify the terminal device 40 of the information of the point cell to be connected.

[0475] The base station 20 transmits RRC signaling information to the terminal device 40 (step S1005). Here, the base station 20 can notify the terminal device 40 of the information of the point cell to be connected.

[0476] <5-2-7. Sequence example according to M2-7>

[0477] Figure 27 is a diagram illustrating a sequence example of an initial access process related to a means of determining a point cell during a 2-step RACH process. Here, the point cell determination means when performing position measurement by transmitting a positioning reference signal (PRS) after random access will be described below. Hereinafter, reference will be made to Figure 27 The initial access process according to the present means will be described.

[0478] The base station 20 transmits a synchronization signal and system information to the terminal device 40 (step S1101).

[0479] The terminal device 40 receives the synchronization signal and the system information. Subsequently, the terminal device 40 transmits a random access preamble and message 3 information to the base station 20 (step S1102). Here, this information can be referred to as message A, or can be referred to as another term.

[0480] The base station 20 transmits a random access response and a contention resolution to the terminal device 40 (step S1103). This information can be referred to as message B, or can be referred to as another term.

[0481] The base station 20 transmits RRC signaling information to the terminal device 40 (step S1104). Here, in order to perform position measurement in the terminal device 40, the base station 20 also transmits a positioning reference signal (PRS) to the terminal device 40 (step S1105).

[0482] The terminal device 40 measures the position of the terminal device 40 using the received PRS (step S1106). Subsequently, the terminal device 40 notifies the base station 20 of the position measurement result with respect to the terminal device 40 (step S1107).

[0483] The base station 20 determines the point cell using the received terminal position information (step S1108). Subsequently, the base station 20 notifies the terminal device 40 of the information of the point cell to be connected (step S1109).

[0484] <5-2-8. Sequence example according to M2-8>

[0485] Figure 28 is a diagram illustrating a sequence example of the initial access processing related to the means of determining the point cell during the 2-step RACH processing. Here, the point cell determination means when the position measurement is performed by transmitting the Sounding Reference Signal (SRS) after the random access will be described below. Hereinafter, the initial access processing according to the present means will be described with reference to Figure 28

[0486] The base station 20 transmits the synchronization signal and the system information to the terminal device 40 (step S1201).

[0487] The terminal device 40 receives the synchronization signal and the system information. Subsequently, the terminal device 40 transmits the random access preamble and the message 3 information to the base station 20 (step S1202). Here, this information can be referred to as the message A, or can be referred to as another term.

[0488] The base station 20 transmits the random access response and the contention resolution to the terminal device 40 (step S1203). This information can be referred to as the message B, or can be referred to as another term. Subsequently, the base station 20 transmits the RRC signaling information to the terminal device 40 (step S1204).

[0489] In order to perform the position measurement, the terminal device 40 transmits the Sounding Reference Signal (SRS) to the base station 20 (step S1205).

[0490] The base station 20 measures the position of the terminal device 40 using the received SRS, and determines the point cell using the terminal position information (step S1206). Subsequently, the base station 20 notifies the terminal device 40 of the information of the point cell to be connected (step S1207).

[0491] <5-3. Point cell determination means based on anchor cell>

[0492] Next, a sequence example of the initial access processing related to the point cell determination means based on the anchor cell will be described. The point cell determination means based on the anchor cell can be one of the following (M3-1) to (M3-2). ​

[0493] (M3-1) Means for determining a point cell by an anchor cell after 4-step RACH processing

[0494] (M3-2) Means for determining a point cell by an anchor cell after 2-step RACH processing

[0495] Hereinafter, a sequence example of the initial access processing in each of (M3-1) to (M3-2) will be described. The following processing is, for example, performed by the control unit 23 (acquisition unit 231, formation unit 232, determination processing unit 233, connection processing unit 234, or measurement unit 235) of the base station 20 and the control unit 43 (determination processing unit 431 or communication control unit 432) of the terminal device 40.

[0496] <5-3-1. Sequence example according to M3-1>

[0497] Figure 29 is a diagram illustrating a sequence example of the initial access processing related to the means for determining a point cell by an anchor cell after 4-step RACH processing. Figure 29 The base station serving as an anchor and the base station providing a point cell shown in (M3-1) can be the same base station, or different base stations. Hereinafter, the initial access processing according to the present means will be described with reference to Figure 29

[0498] The base station 20 serving as an anchor transmits a synchronization signal and system information to the terminal device 40 (step S1301).

[0499] The terminal device 40 receives the synchronization signal and system information. Subsequently, the terminal device 40 transmits a random access preamble to the base station 20 serving as an anchor (step S1302).

[0500] The base station 20 serving as an anchor transmits a random access response to the terminal device 40 (step S1303).

[0501] The terminal device 40 transmits message 3 information in random access to the base station 20 serving as an anchor (step S1304).

[0502] The base station 20 serving as an anchor transmits a contention resolution to the terminal device 40 (step S1305). Subsequently, the base station 20 serving as an anchor transmits RRC signaling information to the terminal device 40 (step S1306). Here, in order to perform position measurement in the terminal device 40, the base station 20 serving as an anchor also transmits a positioning reference signal (PRS) to the terminal device 40 (step S1307).

[0503] ​The terminal device 40 measures the terminal position using the received PRS (step S1308). Subsequently, the terminal device 40 notifies the base station 20 serving as an anchor of the position measurement result (terminal position information) with respect to the terminal device 40 (step S1309).

[0504] The base station 20 serving as an anchor can determine the point cell using the received terminal position information (step S1310). Subsequently, the base station 20 serving as an anchor can transmit information with respect to the determined point cell to the base station 20 providing the point cell, or can transmit the measurement result with respect to the terminal position (step S1311). Here, in the case where the base station 20 serving as an anchor and the base station 20 providing the point cell are the same base station, notification is not necessary.

[0505] Upon receiving the measurement result with respect to the terminal position from the base station 20 serving as an anchor, the base station 20 providing the point cell can determine the point cell from the notified terminal position information (step S1312). Subsequently, the base station 20 providing the point cell notifies the terminal device 40 of information with respect to the point cell to be connected (step S1313).

[0506] The terminal device 40 starts communication in the point cell in addition to communication with the cell serving as an anchor (step S1314). Here, the terminal device 40 can stop communication with the cell serving as an anchor and switch to communication with the point cell, instead of performing addition to the cell serving as an anchor.

[0507] <5-3-2. Sequence example according to M3-2>

[0508] Figure 30 is a diagram illustrating a sequence example of initial access processing related to a means of determining a point cell through an anchor cell after 2-step RACH processing. Figure 30 The base station serving as an anchor and the base station providing the point cell illustrated in FIG. 13A can be the same base station, or different base stations. Hereinafter, the initial access processing according to the present means will be described with reference to Figure 30

[0509] The base station 20 serving as an anchor transmits a synchronization signal and system information to the terminal device 40 (step S1401).

[0510] The terminal device 40 receives the synchronization signal and system information. Subsequently, the terminal device 40 transmits a random access preamble and message 3 information to the base station 20 serving as an anchor (step S1402). Here, this information can be referred to as message A, or can be referred to as another term.

[0511] ​The base station 20 serving as the anchor transmits a random access response and contention resolution to the terminal device 40 (step S1403). This information can be referred to as a message B, or can be referred to as another term. Subsequently, the base station 20 serving as the anchor transmits RRC signaling information to the terminal device 40 (step S1404). Here, in order to perform position measurement in the terminal device 40, the base station 20 serving as the anchor also transmits a positioning reference signal (PRS) to the terminal device 40 (step S1405).

[0512] The terminal device 40 measures a terminal position using the received PRS (step S1406). Subsequently, the terminal device 40 notifies the base station 20 serving as the anchor of a result of position measurement (terminal position information) of the terminal device 40 (step S1407).

[0513] The base station 20 serving as the anchor can determine a point cell using the received terminal position information (step S1408). Subsequently, the base station 20 serving as the anchor can transmit information on the determined point cell to the base station 20 providing the point cell, or can transmit a result of measurement of the terminal position (step S1409). Here, in a case where the base station 20 serving as the anchor and the base station 20 providing the point cell are the same base station, notification is not necessary.

[0514] Upon receiving the result of measurement of the terminal position from the base station 20 serving as the anchor, the base station 20 providing the point cell can determine the point cell from the notified terminal position information (step S1410). Subsequently, the base station 20 providing the point cell notifies the terminal device 40 of information on the point cell to be connected (step S1411).

[0515] The terminal device 40 starts communication in the point cell in addition to communication with the cell serving as the anchor (step S1412). Here, the terminal device 40 can stop communication with the cell serving as the anchor and switch to communication with the point cell, instead of performing addition to the cell serving as the anchor.

[0516] <<6. Modification>>

[0517] The embodiments described above are examples, and various modifications and applications can be made.

[0518] <6-1. Function separation>

[0519] The functions of the base station 20 of the present embodiment can be separated into a plurality of functions such as a Central Unit (CU), a Distributed Unit (DU), and a Radio Unit (RU). Hereinafter, the relationship between the CU / DU / RU separation of the functions of the base station 20 and point shaping will be described.

[0520] Figure 31 is a diagram for illustrating an example of CU / DU / RU separation of the functions of the base station 20. In this diagram, CN denotes a core network. In the current standard, the functions of the base station (e.g., gNB) are separated into two parts: a central unit (CU) and a distributed unit (DU). Here, the DU can include some or all of the functions known by names such as Radio Remote Head (RRH), Remote Radio Unit (RRU), and Radio Unit (RU) in 3GPP LTE.

[0521] Currently, as shown in P1 of Figure 31 , the boundary line (also called a split point or a division point) between the CU and the DU is set at a position between the Packet Data Convergence Protocol layer (PDCP layer) and the Radio Link Control layer (RLC layer) in the 3GPP protocol stack (Option 2). In order to establish communication between the CU and the DU, 3GPP defines “F1” as an interface between these units. This interface is a logical interface. For example, IP packets pass through Ethernet (IEEE 802.3) to establish communication between the CU and the DU.

[0522] For example, when the base station 20 performs point shaping, a configuration is allowed in which an entity that performs central control (e.g., the CU or the DU) processes the Medium Access Control layer (MAC layer) or higher layers, and a transmission antenna group that functions as a transmission point processes the Physical layer (PHY layer) or lower layers.

[0523] For example, the processing (functions) related to point shaping can be separated in accordance with Option 6, Option 7, or Option 8 as shown in Figure 31 . When the processing is separated in Option 6, the central control entity processes the Low-MAC (LoW-MAC) layer or higher layers, and the transmission antenna group processes the High-PHY (High-PHY) layer or lower layers. When the processing is separated in Option 7, the central control entity processes the High-PHY layer or higher layers, and the transmission antenna group processes the Low-PHY (LoW-PHY) layer or lower layers. In the case of separating the processing related to point shaping in Option 8, the central control entity processes the Low-PHY layer or higher layers, and the transmission antenna group processes the RF layer (Radio Frequency layer) or lower layers. Of course, the separation of the processing is not limited to this. The processing can be separated in another option (e.g., one of Options 1 to 5).

[0524] Examples that can be envisaged include separation of the processing (functions) such as P1 to P5 as shown in Figure 31 . The separation of the processing is not limited to the following examples.

[0525] P1: Example of separating the CU and the DU / RU in Option 2

[0526] P2: Example of separating CU / DU and RU in Option 7

[0527] P3: Example of separating CU / DU and RU in Option 8

[0528] P4: Example of separating CU and DU in Option 2, and separating DU and RU in Option 7

[0529] P5: Example of separating CU and DU in Option 2, and separating DU and RU in Option 8

[0530] Figure 32 is a diagram illustrating an example of separation of processing related to point shaping. Specifically, Figure 32 is a diagram illustrating an example of dividing processing into a central control entity and a transmission antenna group, for example, in Option 6. In Figure 32 In the example of, the central control entity processes the SDAP / PDCP / RLC / MAC layers, while the PHY / RF layers are processed at each transmission point.

[0531] This makes it possible to implement efficient point shaping processing.

[0532] <6-2. Point shaping>

[0533] The embodiments described above describe wireless communication using a technique (power concentration technique) that concentrates power at a specific point using a phase difference of a near field. However, the point shaping wireless communication according to the present embodiment can be near field communication. Here, the near field communication can be communication within a distance shorter than a Fraunhofer distance determined from a frequency band and an opening length of a transmission panel.

[0534] In addition, the above-described embodiments describe an example in which one base station 20 performs processing related to point shaping. However, a plurality of base stations 20 can perform the processing related to point shaping in cooperation. For example, a plurality of base stations 20 can form a point cell by cooperatively controlling each transmission antenna with another base station 20. The base station 20 can perform cooperative control with a relay station 30.

[0535] <6-3. Reference signal>

[0536] A point cell is smaller than a conventional cell. Therefore, in the case of applying point shaping to a radio access network, it is assumed that the radio access network has a form in which one point cell is used by one terminal device 40 alone. In the case where one point cell is used by one terminal device 40 alone, there will be no need for multi-user multiple-input multiple-output (multi-user MIMO) with another terminal device 40, and thus it is possible to reduce the number of antenna ports.

[0537] For example, in conventional communication, multiple terminals are simultaneously multiplexed, and thus, with respect to mapping of the reference signal, the reference signal is orthogonally mapped for each terminal device 40 so as to be orthogonal in frequency and time resources. Figure 33 is a diagram illustrating an example of mapping of a conventional reference signal.

[0538] Figure 34 is a diagram illustrating an example of mapping of a reference signal according to the present embodiment. In a case where only one terminal device 40 uses one point cell, there will be no multiplexing with another terminal device 40. Thus, for example, as shown in Figure 34 the reference signal can be mapped in all subcarriers of one symbol. This leads to improvement in communication quality.

[0539] Of course, the reference signal does not have to be mapped on all subcarriers of one symbol. Figure 35 is a diagram illustrating another example of mapping of a reference signal according to the present embodiment. In the example of Figure 35 the reference signal is sparsely mapped. A part of one symbol is assigned as a data signal transmission region. This makes it possible to increase data transmission resources.

[0540] <6-4. Scheduling>

[0541] When only one terminal device 40 uses one point cell, the terminal device 40 does not need to share communication resources with another terminal device 40. Thus, the base station 20 can constantly provide communication resources to a specific terminal device 40 alone. Thus, the base station 20 can omit a part or all of conventional scheduling processing. For example, when performing point shaping (or when only one terminal device 40 uses one point cell), the base station 20 can be configured not to perform at least one of communication resource scheduling in the frequency direction and communication resource scheduling in the time direction. Further, the base station 20 can be configured not to perform cross-carrier scheduling in carrier aggregation or dual connectivity.

[0542] <6-5. Other modifications>

[0543] In the above-described embodiments, the technology of the present disclosure is described with an example of communication processing between the base station 20 and the terminal device 40. However, the range of application of the present embodiments is not limited thereto. For example, the technology of the present disclosure is also applicable to communication between a plurality of communication devices selected from the management device 10, the base station 20, the relay station 30, and the terminal device 40. Further, the technology of the present disclosure is also applicable to communication between the management devices 10, between the base stations 20, between the relay stations 30, or between the terminal devices 40.

[0544] The control device that controls the management device 10, the base station 20, the relay station 30, and the terminal device 40 of the present embodiment can be realized by a special-purpose computer system or a general-purpose computer system.

[0545] For example, a communication program for executing the above-described operation is stored in a computer-readable recording medium such as an optical disc, a semiconductor memory, a magnetic tape, or a floppy disc, and is distributed. For example, the program is installed on a computer, and the above-described processing is executed to realize the configuration of the control device. At this time, the control device can be a device (for example, a personal computer) external to the management device 10, the base station 20, the relay station 30, or the terminal device 40. Further, the control device can be an internal device (for example, the control unit 13, the control unit 23, the control unit 33, or the control unit 43) of the management device 10, the base station 20, the relay station 30, or the terminal device 40.

[0546] Further, for example, the above-described communication program can be stored in a disc device included in a server on a network such as the Internet, so as to be able to be downloaded to a computer. Further, the above-described functions can be realized by cooperatively using an operating system (OS) and application software. In this case, for example, a part other than the OS can be stored in a medium for distribution, or a part other than the OS can be stored in a server so as to be downloaded to a computer.

[0547] Further, among the individual processes described in the above-described embodiments, all or a part of the processes described as being automatically executed can be manually executed, or the processes described as being manually executed can be automatically executed by a known method. Further, unless otherwise specified, the process procedures, specific names, and information including various data and parameters shown in the above-described documents or drawings can be flexibly changed. For example, the various types of information illustrated in each drawing are not limited to the illustrated information.

[0548] Further, each component of each device is provided as an illustration of a function and a concept, and thus does not necessarily need to be physically configured as illustrated. That is, the specific form of distribution / integration of each device is not limited to those shown in the drawings, and all or a part thereof can be functionally or physically distributed or integrated into an optionally determined unit according to various loads and usage states. Such a configuration by distribution or integration can be dynamically performed.

[0549] Further, the above-described embodiments can be appropriately combined within a range capable of realizing without contradicting the processes. Further, the order of the individual steps shown in the flowcharts or sequence diagrams of the above-described embodiments can be appropriately changed.

[0550] Furthermore, the present embodiment can be implemented as any configuration constituting an apparatus or a system, such as a large processor as a large scale integration (LSI) or the like, a module using a plurality of processors, a unit using a plurality of modules, and a collection obtained by further adding other functions to the unit (that is, a configuration of a part of an apparatus).

[0551] In the present embodiment, a system indicates a group of a plurality of components (devices, modules (parts), and the like), and it is not a big problem whether all the components are in the same housing. Therefore, a plurality of devices housed in separate housings and connected via a network, and a device housing a plurality of modules in one housing, are all systems.

[0552] Furthermore, the present embodiment can employ a configuration of cloud computing in which one function is cooperatively shared and processed by a plurality of devices or devices connected via a network.

[0553] <<7. Conclusion>>

[0554] The base station 20 forms a point cell by a power concentration technique (point forming). For example, the base station 20 performs cooperative control of a plurality of antennas to concentrate power in a specific place, thereby forming a point cell. Subsequently, the base station 20 performs processing for determining a point cell to which the terminal device 40 belongs. For example, the base station 20 transmits a plurality of synchronization signals for the terminal device 40 to identify a point cell to the terminal device 40. Subsequently, the terminal device 40 determines a point cell to which the terminal device 40 belongs on the basis of the synchronization signals. Alternatively, the base station 20 determines a point cell PC to which the terminal device 40 belongs on the basis of information from the terminal device 40. Subsequently, the terminal device performs wireless communication using the determined point cell.

[0555] In this way, in the present embodiment, the base station 20 performs processing for determining a point cell to which a terminal device belongs. This enables the terminal device 40 to efficiently access a point cell. This enables the communication system 1 to achieve high communication performance (for example, high frequency efficiency, low latency, and the like).

[0556] Embodiments of the present disclosure are described above. However, the technical scope of the present disclosure is not limited to the embodiments described above, but various changes that do not depart from the scope are possible. Furthermore, combinations of components in different embodiments and modifications are allowed when appropriate.

[0557] The effects described in the individual embodiments of the present specification are merely examples and there can be additional effects other than those exemplified.

[0558] Note that the present technology can also have the following configurations. (1)

[0560] A base station comprising:

[0561] a forming unit configured to form a point cell by concentrating power at a specific place using coordinated control of a plurality of antennas; and

[0562] a determination processing unit configured to perform processing for determining a point cell to which a terminal device belongs. (2)

[0564] The base station according to (1),

[0565] wherein the forming unit forms a plurality of point cells covering a predetermined area, and

[0566] the determination processing unit transmits, to the terminal device, a plurality of synchronization signals for the terminal device to identify a point cell. (3)

[0568] The base station according to (2),

[0569] wherein the determination processing unit transmits the plurality of synchronization signals simultaneously. (4)

[0571] The base station according to (2),

[0572] wherein the determination processing unit transmits the plurality of synchronization signals dispersedly at different times. (5)

[0574] The base station according to (1),

[0575] wherein a wide cell that is a cell having a wider area than the point cell can be formed,

[0576] the forming unit forms one or more wide cells covering a predetermined area, and forms a plurality of point cells covering the wide cell, and

[0577] after the terminal device is connected to the wide cell, the determination processing unit transmits, to the terminal device, a plurality of synchronization signals for the terminal device to identify a point cell included in the wide cell to which the terminal device belongs. (6)

[0579] The base station according to (5),

[0580] wherein the forming unit forms a plurality of wide cells covering a predetermined area, and forms a plurality of point cells covering at least one of the plurality of wide cells, and

[0581] The determination processing unit transmits, to the terminal device, a plurality of synchronization signals for the terminal device to identify the wide cell, and after the terminal device connects to the wide cell determined based on the synchronization signals, the determination processing unit transmits, to the terminal device, a plurality of synchronization signals for the terminal device to identify a point cell included in the wide cell to which the terminal device belongs. (7)

[0583] The base station according to (5) or (6),

[0584] wherein, after the terminal device connects to the wide cell, the determination processing unit transmits, to the terminal device, a plurality of different reference signals associated with the plurality of point cells, and determines the point cell to which the terminal device belongs based on feedback information transmitted from the terminal device with respect to the reference signals. (8)

[0586] The base station according to (5) or (6), further comprising:

[0587] a connection processing unit configured to, after determining the point cell to which the terminal device belongs, perform processing for changing the cell to which the terminal device is connected from the wide cell to the point cell. (9)

[0589] The base station according to (1),

[0590] wherein a cell different from the point cell can be formed,

[0591] the base station further comprising an acquisition unit configured to, during or after the terminal device is connected with the cell different from the point cell, acquire position information of the terminal device, and

[0592] the determination processing unit determines the point cell to which the terminal device belongs based on the position information of the terminal device. (10)

[0594] The base station according to (9), further comprising:

[0595] a measurement unit configured to, during or after the terminal device is connected with the cell different from the point cell, measure a position of the terminal device,

[0596] wherein the acquisition unit acquires the measured position of the terminal device as the position information. (11)

[0598] The base station according to (9),

[0599] wherein the acquisition unit acquires the position information from the terminal device during or after the terminal device is connected with the cell different from the point cell. (12)

[0601] The base station according to (1), further comprising:

[0602] an acquisition unit configured to acquire information from another base station to which a terminal device is connected,

[0603] wherein the determination processing unit determines a point cell to which the terminal device belongs, based on the information acquired from the another base station. (13)

[0605] The base station according to (12),

[0606] wherein the acquisition unit acquires information about the terminal device from the another base station, and

[0607] the determination processing unit determines a point cell to which the terminal device belongs, based on the information acquired from the another base station. (14)

[0609] The base station according to (12),

[0610] wherein the another base station is configured to be able to determine a point cell to which the terminal device belongs,

[0611] the acquisition unit acquires determination information about the point cell to which the terminal device belongs, from the another base station, and

[0612] the determination processing unit determines a point cell to which the terminal device belongs, based on the determination information acquired from the another base station. (15)

[0614] A terminal device capable of connecting to a base station that is capable of forming a point cell by concentrating power at a specific place using coordinated control of a plurality of antennas, the terminal device comprising:

[0615] a determination processing unit configured to perform processing for determining a point cell to which the terminal device belongs; and

[0616] a communication control unit configured to perform communication using the determined point cell. (16)

[0618] The terminal device according to (15),

[0619] wherein the terminal device is configured to be able to combine a plurality of frequency bands using carrier aggregation or dual connectivity, and

[0620] the communication control unit performs communication using at least one of the plurality of frequency bands as a frequency band that provides a point cell. (17)

[0622] The terminal device according to (16),

[0623] wherein the communication control unit performs communication using at least one of the plurality of frequency bands as a frequency band of a point cell and at least another frequency band as a frequency band of a wide cell, the wide cell being a cell having a wider area than the point cell. (18)

[0625] A communication method including:

[0626] forming a point cell by concentrating power at a specific location using coordinated control of a plurality of antennas; and

[0627] performing processing for determining a point cell to which the terminal device belongs. (19)

[0629] A communication method performed by a terminal device capable of connecting to a base station capable of forming a point cell by concentrating power at a specific location using coordinated control of a plurality of antennas, the communication method including:

[0630] performing processing for determining a point cell to which the terminal device belongs; and

[0631] performing communication using a point cell determined by the base station. (20)

[0633] A communication system including: a base station; and a terminal device,

[0634] wherein the base station includes:

[0635] a forming unit configured to form a point cell by concentrating power at a specific location using coordinated control of a plurality of antennas; and

[0636] a first determination processing unit configured to perform processing for determining a point cell to which the terminal device belongs, and

[0637] the terminal device includes:

[0638] a second determination processing unit configured to perform processing for determining a point cell to which the terminal device belongs; and

[0639] a communication control unit configured to perform communication using a point cell determined by the base station.

[0640] List of Reference Signs

[0641] 1 Communication system

[0642] 10 Management device

[0643] 20 Base station

[0644] 30 relay station

[0645] 40 terminal device

[0646] 11 communication unit

[0647] 21, 31, 41 wireless communication unit

[0648] 12, 22, 32, 42 storage unit

[0649] 13, 23, 33, 43 control unit

[0650] 211, 311, 411 transmission processing unit

[0651] 212, 312, 412 reception processing unit

[0652] 213, 313, 413 antenna

[0653] 231, 331 acquisition unit

[0654] 232, 332 formation unit

[0655] 233, 333, 431 determination processing unit

[0656] 234, 334 connection processing unit

[0657] 235, 335 measurement unit

[0658] 432 communication control unit

[0659] RAN radio access network

[0660] CN core network

Claims

1. A base station comprising: a forming unit configured to form a point cell by concentrating power at a specific place using coordinated control of a plurality of antennas; and a determination processing unit configured to perform processing for determining a point cell to which a terminal device belongs.

2. The base station according to claim 1, wherein the forming unit forms a plurality of point cells covering a predetermined area, and the determination processing unit transmits a plurality of synchronization signals for the terminal device to identify a point cell to the terminal device.

3. The base station according to claim 2, wherein the determination processing unit transmits the plurality of synchronization signals simultaneously.

4. The base station according to claim 2, wherein, the determination processing unit transmits the plurality of synchronization signals dispersedly at different times.

5. The base station according to claim 1, wherein a wide cell that is a cell having a wider area than a point cell can be formed, the forming unit forms one or more wide cells covering a predetermined area, and forms a plurality of point cells covering the wide cell, and after the terminal device is connected to the wide cell, the determination processing unit transmits a plurality of synchronization signals for the terminal device to identify a point cell included in the wide cell to which the terminal device belongs to the terminal device.

6. The base station according to claim 5, wherein, the forming unit forms a plurality of wide cells covering a predetermined area, and forms a plurality of point cells covering at least one of the plurality of wide cells, and the determination processing unit transmits a plurality of synchronization signals for the terminal device to identify a wide cell to the terminal device, and after the terminal device is connected to the wide cell determined based on the synchronization signal, the determination processing unit transmits a plurality of synchronization signals for the terminal device to identify a point cell included in the wide cell to which the terminal device belongs to the terminal device.

7. The base station according to claim 5, wherein after the terminal device is connected to the wide cell, the determination processing unit transmits a plurality of different reference signals associated with the plurality of point cells to the terminal device, and determines a point cell to which the terminal device belongs based on feedback information transmitted from the terminal device with respect to the reference signal.

8. The base station according to claim 5, further comprising: a connection processing unit configured to perform processing for changing a cell to which the terminal device is connected from a wide cell to a point cell after determining a point cell to which the terminal device belongs.

9. The base station according to claim 1, wherein a cell different from a point cell can be formed, the base station further comprises an acquisition unit configured to acquire position information of the terminal device during or after the terminal device is connected to the cell different from the point cell, and the determination processing unit determines a point cell to which the terminal device belongs based on the position information of the terminal device.

10. The base station according to claim 9, further comprising: a measurement unit configured to measure a position of the terminal device during or after the terminal device is connected to the cell different from the point cell, wherein the acquisition unit acquires the measured position of the terminal device as the position information.

11. The base station according to claim 9, wherein, the acquisition unit acquires the position information from the terminal device during or after the terminal device is connected to the cell different from the point cell.

12. The base station according to claim 1, further comprising: an acquisition unit configured to acquire information from another base station to which a terminal device is connected, wherein the determination processing unit determines a point cell to which a terminal device belongs, based on the information acquired from the another base station.

13. The base station according to claim 12, wherein the acquisition unit acquires information on a terminal device from the another base station, and the determination processing unit determines a point cell to which a terminal device belongs, based on the information acquired from the another base station.

14. The base station according to claim 12, wherein the another base station is configured to be able to determine a point cell to which a terminal device belongs, the acquisition unit acquires determination information on a point cell to which a terminal device belongs, from the another base station, and the determination processing unit determines a point cell to which a terminal device belongs, based on the determination information acquired from the another base station.

15. A terminal device capable of connecting to a base station that is capable of forming a point cell by concentrating power in a specific place using coordinated control of a plurality of antennas, the terminal device comprising: a determination processing unit configured to execute processing for determining a point cell to which the terminal device belongs; and a communication control unit configured to execute communication using the determined point cell.

16. The terminal device according to claim 15, the terminal device is configured to be able to combine a plurality of frequency bands using carrier aggregation or dual connectivity, and wherein the communication control unit executes communication using at least one of the plurality of frequency bands as a frequency band that provides a point cell.

17. The terminal device according to claim 16, the communication control unit executes communication using at least one of the plurality of frequency bands as a frequency band that provides a point cell and at least another frequency band as a frequency band that provides a wide cell, which is a cell having a wider area than a point cell. wherein 18. A communication method comprising: forming a point cell by concentrating power in a specific place using coordinated control of a plurality of antennas; and executing processing for determining a point cell to which a terminal device belongs.

19. A communication method executed by a terminal device capable of connecting to a base station that is capable of forming a point cell by concentrating power in a specific place using coordinated control of a plurality of antennas, the communication method comprising: executing processing for determining a point cell to which the terminal device belongs; and executing communication using the point cell determined by the base station. a base station; and a terminal device, wherein the base station comprises:

20. A communication system comprising: a formation unit configured to form a point cell by concentrating power in a specific place using coordinated control of a plurality of antennas; and a first determination processing unit configured to execute processing for determining a point cell to which a terminal device belongs, and the terminal device comprises: a second determination processing unit configured to execute processing for determining a point cell to which the terminal device belongs; and a communication control unit configured to execute communication using the point cell determined by the base station. ​ ​ ​

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